| /* Support routines for Value Range Propagation (VRP). |
| Copyright (C) 2005, 2006, 2007 Free Software Foundation, Inc. |
| Contributed by Diego Novillo <dnovillo@redhat.com>. |
| |
| This file is part of GCC. |
| |
| GCC is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 2, or (at your option) |
| any later version. |
| |
| GCC is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| GNU General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with GCC; see the file COPYING. If not, write to |
| the Free Software Foundation, 51 Franklin Street, Fifth Floor, |
| Boston, MA 02110-1301, USA. */ |
| |
| #include "config.h" |
| #include "system.h" |
| #include "coretypes.h" |
| #include "tm.h" |
| #include "ggc.h" |
| #include "flags.h" |
| #include "tree.h" |
| #include "basic-block.h" |
| #include "tree-flow.h" |
| #include "tree-pass.h" |
| #include "tree-dump.h" |
| #include "timevar.h" |
| #include "diagnostic.h" |
| #include "toplev.h" |
| #include "intl.h" |
| #include "cfgloop.h" |
| #include "tree-scalar-evolution.h" |
| #include "tree-ssa-propagate.h" |
| #include "tree-chrec.h" |
| |
| /* Set of SSA names found during the dominator traversal of a |
| sub-graph in find_assert_locations. */ |
| static sbitmap found_in_subgraph; |
| |
| /* Local functions. */ |
| static int compare_values (tree val1, tree val2); |
| static int compare_values_warnv (tree val1, tree val2, bool *); |
| static tree vrp_evaluate_conditional_warnv (tree, bool, bool *); |
| |
| /* Location information for ASSERT_EXPRs. Each instance of this |
| structure describes an ASSERT_EXPR for an SSA name. Since a single |
| SSA name may have more than one assertion associated with it, these |
| locations are kept in a linked list attached to the corresponding |
| SSA name. */ |
| struct assert_locus_d |
| { |
| /* Basic block where the assertion would be inserted. */ |
| basic_block bb; |
| |
| /* Some assertions need to be inserted on an edge (e.g., assertions |
| generated by COND_EXPRs). In those cases, BB will be NULL. */ |
| edge e; |
| |
| /* Pointer to the statement that generated this assertion. */ |
| block_stmt_iterator si; |
| |
| /* Predicate code for the ASSERT_EXPR. Must be COMPARISON_CLASS_P. */ |
| enum tree_code comp_code; |
| |
| /* Value being compared against. */ |
| tree val; |
| |
| /* Next node in the linked list. */ |
| struct assert_locus_d *next; |
| }; |
| |
| typedef struct assert_locus_d *assert_locus_t; |
| |
| /* If bit I is present, it means that SSA name N_i has a list of |
| assertions that should be inserted in the IL. */ |
| static bitmap need_assert_for; |
| |
| /* Array of locations lists where to insert assertions. ASSERTS_FOR[I] |
| holds a list of ASSERT_LOCUS_T nodes that describe where |
| ASSERT_EXPRs for SSA name N_I should be inserted. */ |
| static assert_locus_t *asserts_for; |
| |
| /* Set of blocks visited in find_assert_locations. Used to avoid |
| visiting the same block more than once. */ |
| static sbitmap blocks_visited; |
| |
| /* Value range array. After propagation, VR_VALUE[I] holds the range |
| of values that SSA name N_I may take. */ |
| static value_range_t **vr_value; |
| |
| |
| /* Return whether TYPE should use an overflow infinity distinct from |
| TYPE_{MIN,MAX}_VALUE. We use an overflow infinity value to |
| represent a signed overflow during VRP computations. An infinity |
| is distinct from a half-range, which will go from some number to |
| TYPE_{MIN,MAX}_VALUE. */ |
| |
| static inline bool |
| needs_overflow_infinity (tree type) |
| { |
| return INTEGRAL_TYPE_P (type) && !TYPE_OVERFLOW_WRAPS (type); |
| } |
| |
| /* Return whether TYPE can support our overflow infinity |
| representation: we use the TREE_OVERFLOW flag, which only exists |
| for constants. If TYPE doesn't support this, we don't optimize |
| cases which would require signed overflow--we drop them to |
| VARYING. */ |
| |
| static inline bool |
| supports_overflow_infinity (tree type) |
| { |
| #ifdef ENABLE_CHECKING |
| gcc_assert (needs_overflow_infinity (type)); |
| #endif |
| return (TYPE_MIN_VALUE (type) != NULL_TREE |
| && CONSTANT_CLASS_P (TYPE_MIN_VALUE (type)) |
| && TYPE_MAX_VALUE (type) != NULL_TREE |
| && CONSTANT_CLASS_P (TYPE_MAX_VALUE (type))); |
| } |
| |
| /* VAL is the maximum or minimum value of a type. Return a |
| corresponding overflow infinity. */ |
| |
| static inline tree |
| make_overflow_infinity (tree val) |
| { |
| #ifdef ENABLE_CHECKING |
| gcc_assert (val != NULL_TREE && CONSTANT_CLASS_P (val)); |
| #endif |
| val = copy_node (val); |
| TREE_OVERFLOW (val) = 1; |
| return val; |
| } |
| |
| /* Return a negative overflow infinity for TYPE. */ |
| |
| static inline tree |
| negative_overflow_infinity (tree type) |
| { |
| #ifdef ENABLE_CHECKING |
| gcc_assert (supports_overflow_infinity (type)); |
| #endif |
| return make_overflow_infinity (TYPE_MIN_VALUE (type)); |
| } |
| |
| /* Return a positive overflow infinity for TYPE. */ |
| |
| static inline tree |
| positive_overflow_infinity (tree type) |
| { |
| #ifdef ENABLE_CHECKING |
| gcc_assert (supports_overflow_infinity (type)); |
| #endif |
| return make_overflow_infinity (TYPE_MAX_VALUE (type)); |
| } |
| |
| /* Return whether VAL is a negative overflow infinity. */ |
| |
| static inline bool |
| is_negative_overflow_infinity (tree val) |
| { |
| return (needs_overflow_infinity (TREE_TYPE (val)) |
| && CONSTANT_CLASS_P (val) |
| && TREE_OVERFLOW (val) |
| && operand_equal_p (val, TYPE_MIN_VALUE (TREE_TYPE (val)), 0)); |
| } |
| |
| /* Return whether VAL is a positive overflow infinity. */ |
| |
| static inline bool |
| is_positive_overflow_infinity (tree val) |
| { |
| return (needs_overflow_infinity (TREE_TYPE (val)) |
| && CONSTANT_CLASS_P (val) |
| && TREE_OVERFLOW (val) |
| && operand_equal_p (val, TYPE_MAX_VALUE (TREE_TYPE (val)), 0)); |
| } |
| |
| /* Return whether VAL is a positive or negative overflow infinity. */ |
| |
| static inline bool |
| is_overflow_infinity (tree val) |
| { |
| return (needs_overflow_infinity (TREE_TYPE (val)) |
| && CONSTANT_CLASS_P (val) |
| && TREE_OVERFLOW (val) |
| && (operand_equal_p (val, TYPE_MAX_VALUE (TREE_TYPE (val)), 0) |
| || operand_equal_p (val, TYPE_MIN_VALUE (TREE_TYPE (val)), 0))); |
| } |
| |
| /* If VAL is now an overflow infinity, return VAL. Otherwise, return |
| the same value with TREE_OVERFLOW clear. This can be used to avoid |
| confusing a regular value with an overflow value. */ |
| |
| static inline tree |
| avoid_overflow_infinity (tree val) |
| { |
| if (!is_overflow_infinity (val)) |
| return val; |
| |
| if (operand_equal_p (val, TYPE_MAX_VALUE (TREE_TYPE (val)), 0)) |
| return TYPE_MAX_VALUE (TREE_TYPE (val)); |
| else |
| { |
| #ifdef ENABLE_CHECKING |
| gcc_assert (operand_equal_p (val, TYPE_MIN_VALUE (TREE_TYPE (val)), 0)); |
| #endif |
| return TYPE_MIN_VALUE (TREE_TYPE (val)); |
| } |
| } |
| |
| |
| /* Return whether VAL is equal to the maximum value of its type. This |
| will be true for a positive overflow infinity. We can't do a |
| simple equality comparison with TYPE_MAX_VALUE because C typedefs |
| and Ada subtypes can produce types whose TYPE_MAX_VALUE is not == |
| to the integer constant with the same value in the type. */ |
| |
| static inline bool |
| vrp_val_is_max (tree val) |
| { |
| tree type_max = TYPE_MAX_VALUE (TREE_TYPE (val)); |
| |
| return (val == type_max |
| || (type_max != NULL_TREE |
| && operand_equal_p (val, type_max, 0))); |
| } |
| |
| /* Return whether VAL is equal to the minimum value of its type. This |
| will be true for a negative overflow infinity. */ |
| |
| static inline bool |
| vrp_val_is_min (tree val) |
| { |
| tree type_min = TYPE_MIN_VALUE (TREE_TYPE (val)); |
| |
| return (val == type_min |
| || (type_min != NULL_TREE |
| && operand_equal_p (val, type_min, 0))); |
| } |
| |
| |
| /* Return true if ARG is marked with the nonnull attribute in the |
| current function signature. */ |
| |
| static bool |
| nonnull_arg_p (tree arg) |
| { |
| tree t, attrs, fntype; |
| unsigned HOST_WIDE_INT arg_num; |
| |
| gcc_assert (TREE_CODE (arg) == PARM_DECL && POINTER_TYPE_P (TREE_TYPE (arg))); |
| |
| /* The static chain decl is always non null. */ |
| if (arg == cfun->static_chain_decl) |
| return true; |
| |
| fntype = TREE_TYPE (current_function_decl); |
| attrs = lookup_attribute ("nonnull", TYPE_ATTRIBUTES (fntype)); |
| |
| /* If "nonnull" wasn't specified, we know nothing about the argument. */ |
| if (attrs == NULL_TREE) |
| return false; |
| |
| /* If "nonnull" applies to all the arguments, then ARG is non-null. */ |
| if (TREE_VALUE (attrs) == NULL_TREE) |
| return true; |
| |
| /* Get the position number for ARG in the function signature. */ |
| for (arg_num = 1, t = DECL_ARGUMENTS (current_function_decl); |
| t; |
| t = TREE_CHAIN (t), arg_num++) |
| { |
| if (t == arg) |
| break; |
| } |
| |
| gcc_assert (t == arg); |
| |
| /* Now see if ARG_NUM is mentioned in the nonnull list. */ |
| for (t = TREE_VALUE (attrs); t; t = TREE_CHAIN (t)) |
| { |
| if (compare_tree_int (TREE_VALUE (t), arg_num) == 0) |
| return true; |
| } |
| |
| return false; |
| } |
| |
| |
| /* Set value range VR to {T, MIN, MAX, EQUIV}. */ |
| |
| static void |
| set_value_range (value_range_t *vr, enum value_range_type t, tree min, |
| tree max, bitmap equiv) |
| { |
| #if defined ENABLE_CHECKING |
| /* Check the validity of the range. */ |
| if (t == VR_RANGE || t == VR_ANTI_RANGE) |
| { |
| int cmp; |
| |
| gcc_assert (min && max); |
| |
| if (INTEGRAL_TYPE_P (TREE_TYPE (min)) && t == VR_ANTI_RANGE) |
| gcc_assert (!vrp_val_is_min (min) || !vrp_val_is_max (max)); |
| |
| cmp = compare_values (min, max); |
| gcc_assert (cmp == 0 || cmp == -1 || cmp == -2); |
| |
| if (needs_overflow_infinity (TREE_TYPE (min))) |
| gcc_assert (!is_overflow_infinity (min) |
| || !is_overflow_infinity (max)); |
| } |
| |
| if (t == VR_UNDEFINED || t == VR_VARYING) |
| gcc_assert (min == NULL_TREE && max == NULL_TREE); |
| |
| if (t == VR_UNDEFINED || t == VR_VARYING) |
| gcc_assert (equiv == NULL || bitmap_empty_p (equiv)); |
| #endif |
| |
| vr->type = t; |
| vr->min = min; |
| vr->max = max; |
| |
| /* Since updating the equivalence set involves deep copying the |
| bitmaps, only do it if absolutely necessary. */ |
| if (vr->equiv == NULL) |
| vr->equiv = BITMAP_ALLOC (NULL); |
| |
| if (equiv != vr->equiv) |
| { |
| if (equiv && !bitmap_empty_p (equiv)) |
| bitmap_copy (vr->equiv, equiv); |
| else |
| bitmap_clear (vr->equiv); |
| } |
| } |
| |
| |
| /* Copy value range FROM into value range TO. */ |
| |
| static inline void |
| copy_value_range (value_range_t *to, value_range_t *from) |
| { |
| set_value_range (to, from->type, from->min, from->max, from->equiv); |
| } |
| |
| |
| /* Set value range VR to VR_VARYING. */ |
| |
| static inline void |
| set_value_range_to_varying (value_range_t *vr) |
| { |
| vr->type = VR_VARYING; |
| vr->min = vr->max = NULL_TREE; |
| if (vr->equiv) |
| bitmap_clear (vr->equiv); |
| } |
| |
| /* Set value range VR to a single value. This function is only called |
| with values we get from statements, and exists to clear the |
| TREE_OVERFLOW flag so that we don't think we have an overflow |
| infinity when we shouldn't. */ |
| |
| static inline void |
| set_value_range_to_value (value_range_t *vr, tree val, bitmap equiv) |
| { |
| gcc_assert (is_gimple_min_invariant (val)); |
| val = avoid_overflow_infinity (val); |
| set_value_range (vr, VR_RANGE, val, val, equiv); |
| } |
| |
| /* Set value range VR to a non-negative range of type TYPE. |
| OVERFLOW_INFINITY indicates whether to use a overflow infinity |
| rather than TYPE_MAX_VALUE; this should be true if we determine |
| that the range is nonnegative based on the assumption that signed |
| overflow does not occur. */ |
| |
| static inline void |
| set_value_range_to_nonnegative (value_range_t *vr, tree type, |
| bool overflow_infinity) |
| { |
| tree zero; |
| |
| if (overflow_infinity && !supports_overflow_infinity (type)) |
| { |
| set_value_range_to_varying (vr); |
| return; |
| } |
| |
| zero = build_int_cst (type, 0); |
| set_value_range (vr, VR_RANGE, zero, |
| (overflow_infinity |
| ? positive_overflow_infinity (type) |
| : TYPE_MAX_VALUE (type)), |
| vr->equiv); |
| } |
| |
| /* Set value range VR to a non-NULL range of type TYPE. */ |
| |
| static inline void |
| set_value_range_to_nonnull (value_range_t *vr, tree type) |
| { |
| tree zero = build_int_cst (type, 0); |
| set_value_range (vr, VR_ANTI_RANGE, zero, zero, vr->equiv); |
| } |
| |
| |
| /* Set value range VR to a NULL range of type TYPE. */ |
| |
| static inline void |
| set_value_range_to_null (value_range_t *vr, tree type) |
| { |
| set_value_range_to_value (vr, build_int_cst (type, 0), vr->equiv); |
| } |
| |
| |
| /* Set value range VR to VR_UNDEFINED. */ |
| |
| static inline void |
| set_value_range_to_undefined (value_range_t *vr) |
| { |
| vr->type = VR_UNDEFINED; |
| vr->min = vr->max = NULL_TREE; |
| if (vr->equiv) |
| bitmap_clear (vr->equiv); |
| } |
| |
| |
| /* Return value range information for VAR. |
| |
| If we have no values ranges recorded (ie, VRP is not running), then |
| return NULL. Otherwise create an empty range if none existed for VAR. */ |
| |
| static value_range_t * |
| get_value_range (tree var) |
| { |
| value_range_t *vr; |
| tree sym; |
| unsigned ver = SSA_NAME_VERSION (var); |
| |
| /* If we have no recorded ranges, then return NULL. */ |
| if (! vr_value) |
| return NULL; |
| |
| vr = vr_value[ver]; |
| if (vr) |
| return vr; |
| |
| /* Create a default value range. */ |
| vr_value[ver] = vr = XNEW (value_range_t); |
| memset (vr, 0, sizeof (*vr)); |
| |
| /* Allocate an equivalence set. */ |
| vr->equiv = BITMAP_ALLOC (NULL); |
| |
| /* If VAR is a default definition, the variable can take any value |
| in VAR's type. */ |
| sym = SSA_NAME_VAR (var); |
| if (var == default_def (sym)) |
| { |
| /* Try to use the "nonnull" attribute to create ~[0, 0] |
| anti-ranges for pointers. Note that this is only valid with |
| default definitions of PARM_DECLs. */ |
| if (TREE_CODE (sym) == PARM_DECL |
| && POINTER_TYPE_P (TREE_TYPE (sym)) |
| && nonnull_arg_p (sym)) |
| set_value_range_to_nonnull (vr, TREE_TYPE (sym)); |
| else |
| set_value_range_to_varying (vr); |
| } |
| |
| return vr; |
| } |
| |
| /* Return true, if VAL1 and VAL2 are equal values for VRP purposes. */ |
| |
| static inline bool |
| vrp_operand_equal_p (tree val1, tree val2) |
| { |
| if (val1 == val2) |
| return true; |
| if (!val1 || !val2 || !operand_equal_p (val1, val2, 0)) |
| return false; |
| if (is_overflow_infinity (val1)) |
| return is_overflow_infinity (val2); |
| return true; |
| } |
| |
| /* Return true, if the bitmaps B1 and B2 are equal. */ |
| |
| static inline bool |
| vrp_bitmap_equal_p (bitmap b1, bitmap b2) |
| { |
| return (b1 == b2 |
| || (b1 && b2 |
| && bitmap_equal_p (b1, b2))); |
| } |
| |
| /* Update the value range and equivalence set for variable VAR to |
| NEW_VR. Return true if NEW_VR is different from VAR's previous |
| value. |
| |
| NOTE: This function assumes that NEW_VR is a temporary value range |
| object created for the sole purpose of updating VAR's range. The |
| storage used by the equivalence set from NEW_VR will be freed by |
| this function. Do not call update_value_range when NEW_VR |
| is the range object associated with another SSA name. */ |
| |
| static inline bool |
| update_value_range (tree var, value_range_t *new_vr) |
| { |
| value_range_t *old_vr; |
| bool is_new; |
| |
| /* Update the value range, if necessary. */ |
| old_vr = get_value_range (var); |
| is_new = old_vr->type != new_vr->type |
| || !vrp_operand_equal_p (old_vr->min, new_vr->min) |
| || !vrp_operand_equal_p (old_vr->max, new_vr->max) |
| || !vrp_bitmap_equal_p (old_vr->equiv, new_vr->equiv); |
| |
| if (is_new) |
| set_value_range (old_vr, new_vr->type, new_vr->min, new_vr->max, |
| new_vr->equiv); |
| |
| BITMAP_FREE (new_vr->equiv); |
| new_vr->equiv = NULL; |
| |
| return is_new; |
| } |
| |
| |
| /* Add VAR and VAR's equivalence set to EQUIV. */ |
| |
| static void |
| add_equivalence (bitmap equiv, tree var) |
| { |
| unsigned ver = SSA_NAME_VERSION (var); |
| value_range_t *vr = vr_value[ver]; |
| |
| bitmap_set_bit (equiv, ver); |
| if (vr && vr->equiv) |
| bitmap_ior_into (equiv, vr->equiv); |
| } |
| |
| |
| /* Return true if VR is ~[0, 0]. */ |
| |
| static inline bool |
| range_is_nonnull (value_range_t *vr) |
| { |
| return vr->type == VR_ANTI_RANGE |
| && integer_zerop (vr->min) |
| && integer_zerop (vr->max); |
| } |
| |
| |
| /* Return true if VR is [0, 0]. */ |
| |
| static inline bool |
| range_is_null (value_range_t *vr) |
| { |
| return vr->type == VR_RANGE |
| && integer_zerop (vr->min) |
| && integer_zerop (vr->max); |
| } |
| |
| |
| /* Return true if value range VR involves at least one symbol. */ |
| |
| static inline bool |
| symbolic_range_p (value_range_t *vr) |
| { |
| return (!is_gimple_min_invariant (vr->min) |
| || !is_gimple_min_invariant (vr->max)); |
| } |
| |
| /* Return true if value range VR uses a overflow infinity. */ |
| |
| static inline bool |
| overflow_infinity_range_p (value_range_t *vr) |
| { |
| return (vr->type == VR_RANGE |
| && (is_overflow_infinity (vr->min) |
| || is_overflow_infinity (vr->max))); |
| } |
| |
| /* Return false if we can not make a valid comparison based on VR; |
| this will be the case if it uses an overflow infinity and overflow |
| is not undefined (i.e., -fno-strict-overflow is in effect). |
| Otherwise return true, and set *STRICT_OVERFLOW_P to true if VR |
| uses an overflow infinity. */ |
| |
| static bool |
| usable_range_p (value_range_t *vr, bool *strict_overflow_p) |
| { |
| gcc_assert (vr->type == VR_RANGE); |
| if (is_overflow_infinity (vr->min)) |
| { |
| *strict_overflow_p = true; |
| if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (vr->min))) |
| return false; |
| } |
| if (is_overflow_infinity (vr->max)) |
| { |
| *strict_overflow_p = true; |
| if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (vr->max))) |
| return false; |
| } |
| return true; |
| } |
| |
| |
| /* Like tree_expr_nonnegative_warnv_p, but this function uses value |
| ranges obtained so far. */ |
| |
| static bool |
| vrp_expr_computes_nonnegative (tree expr, bool *strict_overflow_p) |
| { |
| return tree_expr_nonnegative_warnv_p (expr, strict_overflow_p); |
| } |
| |
| /* Like tree_expr_nonzero_warnv_p, but this function uses value ranges |
| obtained so far. */ |
| |
| static bool |
| vrp_expr_computes_nonzero (tree expr, bool *strict_overflow_p) |
| { |
| if (tree_expr_nonzero_warnv_p (expr, strict_overflow_p)) |
| return true; |
| |
| /* If we have an expression of the form &X->a, then the expression |
| is nonnull if X is nonnull. */ |
| if (TREE_CODE (expr) == ADDR_EXPR) |
| { |
| tree base = get_base_address (TREE_OPERAND (expr, 0)); |
| |
| if (base != NULL_TREE |
| && TREE_CODE (base) == INDIRECT_REF |
| && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME) |
| { |
| value_range_t *vr = get_value_range (TREE_OPERAND (base, 0)); |
| if (range_is_nonnull (vr)) |
| return true; |
| } |
| } |
| |
| return false; |
| } |
| |
| /* Returns true if EXPR is a valid value (as expected by compare_values) -- |
| a gimple invariant, or SSA_NAME +- CST. */ |
| |
| static bool |
| valid_value_p (tree expr) |
| { |
| if (TREE_CODE (expr) == SSA_NAME) |
| return true; |
| |
| if (TREE_CODE (expr) == PLUS_EXPR |
| || TREE_CODE (expr) == MINUS_EXPR) |
| return (TREE_CODE (TREE_OPERAND (expr, 0)) == SSA_NAME |
| && TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST); |
| |
| return is_gimple_min_invariant (expr); |
| } |
| |
| /* Compare two values VAL1 and VAL2. Return |
| |
| -2 if VAL1 and VAL2 cannot be compared at compile-time, |
| -1 if VAL1 < VAL2, |
| 0 if VAL1 == VAL2, |
| +1 if VAL1 > VAL2, and |
| +2 if VAL1 != VAL2 |
| |
| This is similar to tree_int_cst_compare but supports pointer values |
| and values that cannot be compared at compile time. |
| |
| If STRICT_OVERFLOW_P is not NULL, then set *STRICT_OVERFLOW_P to |
| true if the return value is only valid if we assume that signed |
| overflow is undefined. */ |
| |
| static int |
| compare_values_warnv (tree val1, tree val2, bool *strict_overflow_p) |
| { |
| if (val1 == val2) |
| return 0; |
| |
| /* Below we rely on the fact that VAL1 and VAL2 are both pointers or |
| both integers. */ |
| gcc_assert (POINTER_TYPE_P (TREE_TYPE (val1)) |
| == POINTER_TYPE_P (TREE_TYPE (val2))); |
| |
| if ((TREE_CODE (val1) == SSA_NAME |
| || TREE_CODE (val1) == PLUS_EXPR |
| || TREE_CODE (val1) == MINUS_EXPR) |
| && (TREE_CODE (val2) == SSA_NAME |
| || TREE_CODE (val2) == PLUS_EXPR |
| || TREE_CODE (val2) == MINUS_EXPR)) |
| { |
| tree n1, c1, n2, c2; |
| enum tree_code code1, code2; |
| |
| /* If VAL1 and VAL2 are of the form 'NAME [+-] CST' or 'NAME', |
| return -1 or +1 accordingly. If VAL1 and VAL2 don't use the |
| same name, return -2. */ |
| if (TREE_CODE (val1) == SSA_NAME) |
| { |
| code1 = SSA_NAME; |
| n1 = val1; |
| c1 = NULL_TREE; |
| } |
| else |
| { |
| code1 = TREE_CODE (val1); |
| n1 = TREE_OPERAND (val1, 0); |
| c1 = TREE_OPERAND (val1, 1); |
| if (tree_int_cst_sgn (c1) == -1) |
| { |
| if (is_negative_overflow_infinity (c1)) |
| return -2; |
| c1 = fold_unary_to_constant (NEGATE_EXPR, TREE_TYPE (c1), c1); |
| if (!c1) |
| return -2; |
| code1 = code1 == MINUS_EXPR ? PLUS_EXPR : MINUS_EXPR; |
| } |
| } |
| |
| if (TREE_CODE (val2) == SSA_NAME) |
| { |
| code2 = SSA_NAME; |
| n2 = val2; |
| c2 = NULL_TREE; |
| } |
| else |
| { |
| code2 = TREE_CODE (val2); |
| n2 = TREE_OPERAND (val2, 0); |
| c2 = TREE_OPERAND (val2, 1); |
| if (tree_int_cst_sgn (c2) == -1) |
| { |
| if (is_negative_overflow_infinity (c2)) |
| return -2; |
| c2 = fold_unary_to_constant (NEGATE_EXPR, TREE_TYPE (c2), c2); |
| if (!c2) |
| return -2; |
| code2 = code2 == MINUS_EXPR ? PLUS_EXPR : MINUS_EXPR; |
| } |
| } |
| |
| /* Both values must use the same name. */ |
| if (n1 != n2) |
| return -2; |
| |
| if (code1 == SSA_NAME |
| && code2 == SSA_NAME) |
| /* NAME == NAME */ |
| return 0; |
| |
| /* If overflow is defined we cannot simplify more. */ |
| if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (val1))) |
| return -2; |
| |
| if (strict_overflow_p != NULL |
| && (code1 == SSA_NAME || !TREE_NO_WARNING (val1)) |
| && (code2 == SSA_NAME || !TREE_NO_WARNING (val2))) |
| *strict_overflow_p = true; |
| |
| if (code1 == SSA_NAME) |
| { |
| if (code2 == PLUS_EXPR) |
| /* NAME < NAME + CST */ |
| return -1; |
| else if (code2 == MINUS_EXPR) |
| /* NAME > NAME - CST */ |
| return 1; |
| } |
| else if (code1 == PLUS_EXPR) |
| { |
| if (code2 == SSA_NAME) |
| /* NAME + CST > NAME */ |
| return 1; |
| else if (code2 == PLUS_EXPR) |
| /* NAME + CST1 > NAME + CST2, if CST1 > CST2 */ |
| return compare_values_warnv (c1, c2, strict_overflow_p); |
| else if (code2 == MINUS_EXPR) |
| /* NAME + CST1 > NAME - CST2 */ |
| return 1; |
| } |
| else if (code1 == MINUS_EXPR) |
| { |
| if (code2 == SSA_NAME) |
| /* NAME - CST < NAME */ |
| return -1; |
| else if (code2 == PLUS_EXPR) |
| /* NAME - CST1 < NAME + CST2 */ |
| return -1; |
| else if (code2 == MINUS_EXPR) |
| /* NAME - CST1 > NAME - CST2, if CST1 < CST2. Notice that |
| C1 and C2 are swapped in the call to compare_values. */ |
| return compare_values_warnv (c2, c1, strict_overflow_p); |
| } |
| |
| gcc_unreachable (); |
| } |
| |
| /* We cannot compare non-constants. */ |
| if (!is_gimple_min_invariant (val1) || !is_gimple_min_invariant (val2)) |
| return -2; |
| |
| if (!POINTER_TYPE_P (TREE_TYPE (val1))) |
| { |
| /* We cannot compare overflowed values, except for overflow |
| infinities. */ |
| if (TREE_OVERFLOW (val1) || TREE_OVERFLOW (val2)) |
| { |
| if (strict_overflow_p != NULL) |
| *strict_overflow_p = true; |
| if (is_negative_overflow_infinity (val1)) |
| return is_negative_overflow_infinity (val2) ? 0 : -1; |
| else if (is_negative_overflow_infinity (val2)) |
| return 1; |
| else if (is_positive_overflow_infinity (val1)) |
| return is_positive_overflow_infinity (val2) ? 0 : 1; |
| else if (is_positive_overflow_infinity (val2)) |
| return -1; |
| return -2; |
| } |
| |
| return tree_int_cst_compare (val1, val2); |
| } |
| else |
| { |
| tree t; |
| |
| /* First see if VAL1 and VAL2 are not the same. */ |
| if (val1 == val2 || operand_equal_p (val1, val2, 0)) |
| return 0; |
| |
| /* If VAL1 is a lower address than VAL2, return -1. */ |
| t = fold_binary (LT_EXPR, boolean_type_node, val1, val2); |
| if (t == boolean_true_node) |
| return -1; |
| |
| /* If VAL1 is a higher address than VAL2, return +1. */ |
| t = fold_binary (GT_EXPR, boolean_type_node, val1, val2); |
| if (t == boolean_true_node) |
| return 1; |
| |
| /* If VAL1 is different than VAL2, return +2. */ |
| t = fold_binary (NE_EXPR, boolean_type_node, val1, val2); |
| if (t == boolean_true_node) |
| return 2; |
| |
| return -2; |
| } |
| } |
| |
| /* Compare values like compare_values_warnv, but treat comparisons of |
| nonconstants which rely on undefined overflow as incomparable. */ |
| |
| static int |
| compare_values (tree val1, tree val2) |
| { |
| bool sop; |
| int ret; |
| |
| sop = false; |
| ret = compare_values_warnv (val1, val2, &sop); |
| if (sop |
| && (!is_gimple_min_invariant (val1) || !is_gimple_min_invariant (val2))) |
| ret = -2; |
| return ret; |
| } |
| |
| |
| /* Return 1 if VAL is inside value range VR (VR->MIN <= VAL <= VR->MAX), |
| 0 if VAL is not inside VR, |
| -2 if we cannot tell either way. |
| |
| FIXME, the current semantics of this functions are a bit quirky |
| when taken in the context of VRP. In here we do not care |
| about VR's type. If VR is the anti-range ~[3, 5] the call |
| value_inside_range (4, VR) will return 1. |
| |
| This is counter-intuitive in a strict sense, but the callers |
| currently expect this. They are calling the function |
| merely to determine whether VR->MIN <= VAL <= VR->MAX. The |
| callers are applying the VR_RANGE/VR_ANTI_RANGE semantics |
| themselves. |
| |
| This also applies to value_ranges_intersect_p and |
| range_includes_zero_p. The semantics of VR_RANGE and |
| VR_ANTI_RANGE should be encoded here, but that also means |
| adapting the users of these functions to the new semantics. */ |
| |
| static inline int |
| value_inside_range (tree val, value_range_t *vr) |
| { |
| tree cmp1, cmp2; |
| |
| fold_defer_overflow_warnings (); |
| |
| cmp1 = fold_binary_to_constant (GE_EXPR, boolean_type_node, val, vr->min); |
| if (!cmp1) |
| { |
| fold_undefer_and_ignore_overflow_warnings (); |
| return -2; |
| } |
| |
| cmp2 = fold_binary_to_constant (LE_EXPR, boolean_type_node, val, vr->max); |
| |
| fold_undefer_and_ignore_overflow_warnings (); |
| |
| if (!cmp2) |
| return -2; |
| |
| /* APPLE LOCAL begin 5562718 rewritten on mainline */ |
| /* Insure cmp1 and cmp2 are constants. */ |
| if ((cmp1 != boolean_true_node && cmp1 != boolean_false_node) |
| || (cmp2 != boolean_true_node && cmp2 != boolean_false_node)) |
| return -2; |
| /* APPLE LOCAL end 5562718 rewritten on mainline */ |
| |
| return cmp1 == boolean_true_node && cmp2 == boolean_true_node; |
| } |
| |
| |
| /* Return true if value ranges VR0 and VR1 have a non-empty |
| intersection. */ |
| |
| static inline bool |
| value_ranges_intersect_p (value_range_t *vr0, value_range_t *vr1) |
| { |
| return (value_inside_range (vr1->min, vr0) == 1 |
| || value_inside_range (vr1->max, vr0) == 1 |
| || value_inside_range (vr0->min, vr1) == 1 |
| || value_inside_range (vr0->max, vr1) == 1); |
| } |
| |
| |
| /* Return true if VR includes the value zero, false otherwise. FIXME, |
| currently this will return false for an anti-range like ~[-4, 3]. |
| This will be wrong when the semantics of value_inside_range are |
| modified (currently the users of this function expect these |
| semantics). */ |
| |
| static inline bool |
| range_includes_zero_p (value_range_t *vr) |
| { |
| tree zero; |
| |
| gcc_assert (vr->type != VR_UNDEFINED |
| && vr->type != VR_VARYING |
| && !symbolic_range_p (vr)); |
| |
| zero = build_int_cst (TREE_TYPE (vr->min), 0); |
| /* APPLE LOCAL begin 5562718 rewritten on mainline */ |
| switch (value_inside_range (zero, vr)) |
| { |
| case 1: /* Range includes zero. */ |
| case -2: /* Can't tell if range includes zero. */ |
| return TRUE; |
| default: /* Range does not include zero. */ |
| return FALSE; |
| } |
| /* APPLE LOCAL end 5562718 rewritten on mainline */ |
| } |
| |
| /* Return true if T, an SSA_NAME, is known to be nonnegative. Return |
| false otherwise or if no value range information is available. */ |
| |
| bool |
| ssa_name_nonnegative_p (tree t) |
| { |
| value_range_t *vr = get_value_range (t); |
| |
| if (!vr) |
| return false; |
| |
| /* Testing for VR_ANTI_RANGE is not useful here as any anti-range |
| which would return a useful value should be encoded as a VR_RANGE. */ |
| if (vr->type == VR_RANGE) |
| { |
| int result = compare_values (vr->min, integer_zero_node); |
| |
| return (result == 0 || result == 1); |
| } |
| return false; |
| } |
| |
| /* Return true if T, an SSA_NAME, is known to be nonzero. Return |
| false otherwise or if no value range information is available. */ |
| |
| bool |
| ssa_name_nonzero_p (tree t) |
| { |
| value_range_t *vr = get_value_range (t); |
| |
| if (!vr) |
| return false; |
| |
| /* A VR_RANGE which does not include zero is a nonzero value. */ |
| if (vr->type == VR_RANGE && !symbolic_range_p (vr)) |
| return ! range_includes_zero_p (vr); |
| |
| /* A VR_ANTI_RANGE which does include zero is a nonzero value. */ |
| if (vr->type == VR_ANTI_RANGE && !symbolic_range_p (vr)) |
| return range_includes_zero_p (vr); |
| |
| return false; |
| } |
| |
| |
| /* Extract value range information from an ASSERT_EXPR EXPR and store |
| it in *VR_P. */ |
| |
| static void |
| extract_range_from_assert (value_range_t *vr_p, tree expr) |
| { |
| tree var, cond, limit, min, max, type; |
| value_range_t *var_vr, *limit_vr; |
| enum tree_code cond_code; |
| |
| var = ASSERT_EXPR_VAR (expr); |
| cond = ASSERT_EXPR_COND (expr); |
| |
| gcc_assert (COMPARISON_CLASS_P (cond)); |
| |
| /* Find VAR in the ASSERT_EXPR conditional. */ |
| if (var == TREE_OPERAND (cond, 0)) |
| { |
| /* If the predicate is of the form VAR COMP LIMIT, then we just |
| take LIMIT from the RHS and use the same comparison code. */ |
| limit = TREE_OPERAND (cond, 1); |
| cond_code = TREE_CODE (cond); |
| } |
| else |
| { |
| /* If the predicate is of the form LIMIT COMP VAR, then we need |
| to flip around the comparison code to create the proper range |
| for VAR. */ |
| limit = TREE_OPERAND (cond, 0); |
| cond_code = swap_tree_comparison (TREE_CODE (cond)); |
| } |
| |
| limit = avoid_overflow_infinity (limit); |
| |
| type = TREE_TYPE (limit); |
| gcc_assert (limit != var); |
| |
| /* For pointer arithmetic, we only keep track of pointer equality |
| and inequality. */ |
| if (POINTER_TYPE_P (type) && cond_code != NE_EXPR && cond_code != EQ_EXPR) |
| { |
| set_value_range_to_varying (vr_p); |
| return; |
| } |
| |
| /* If LIMIT is another SSA name and LIMIT has a range of its own, |
| try to use LIMIT's range to avoid creating symbolic ranges |
| unnecessarily. */ |
| limit_vr = (TREE_CODE (limit) == SSA_NAME) ? get_value_range (limit) : NULL; |
| |
| /* LIMIT's range is only interesting if it has any useful information. */ |
| if (limit_vr |
| && (limit_vr->type == VR_UNDEFINED |
| || limit_vr->type == VR_VARYING |
| || symbolic_range_p (limit_vr))) |
| limit_vr = NULL; |
| |
| /* Initially, the new range has the same set of equivalences of |
| VAR's range. This will be revised before returning the final |
| value. Since assertions may be chained via mutually exclusive |
| predicates, we will need to trim the set of equivalences before |
| we are done. */ |
| gcc_assert (vr_p->equiv == NULL); |
| vr_p->equiv = BITMAP_ALLOC (NULL); |
| add_equivalence (vr_p->equiv, var); |
| |
| /* Extract a new range based on the asserted comparison for VAR and |
| LIMIT's value range. Notice that if LIMIT has an anti-range, we |
| will only use it for equality comparisons (EQ_EXPR). For any |
| other kind of assertion, we cannot derive a range from LIMIT's |
| anti-range that can be used to describe the new range. For |
| instance, ASSERT_EXPR <x_2, x_2 <= b_4>. If b_4 is ~[2, 10], |
| then b_4 takes on the ranges [-INF, 1] and [11, +INF]. There is |
| no single range for x_2 that could describe LE_EXPR, so we might |
| as well build the range [b_4, +INF] for it. */ |
| if (cond_code == EQ_EXPR) |
| { |
| enum value_range_type range_type; |
| |
| if (limit_vr) |
| { |
| range_type = limit_vr->type; |
| min = limit_vr->min; |
| max = limit_vr->max; |
| } |
| else |
| { |
| range_type = VR_RANGE; |
| min = limit; |
| max = limit; |
| } |
| |
| set_value_range (vr_p, range_type, min, max, vr_p->equiv); |
| |
| /* When asserting the equality VAR == LIMIT and LIMIT is another |
| SSA name, the new range will also inherit the equivalence set |
| from LIMIT. */ |
| if (TREE_CODE (limit) == SSA_NAME) |
| add_equivalence (vr_p->equiv, limit); |
| } |
| else if (cond_code == NE_EXPR) |
| { |
| /* As described above, when LIMIT's range is an anti-range and |
| this assertion is an inequality (NE_EXPR), then we cannot |
| derive anything from the anti-range. For instance, if |
| LIMIT's range was ~[0, 0], the assertion 'VAR != LIMIT' does |
| not imply that VAR's range is [0, 0]. So, in the case of |
| anti-ranges, we just assert the inequality using LIMIT and |
| not its anti-range. |
| |
| If LIMIT_VR is a range, we can only use it to build a new |
| anti-range if LIMIT_VR is a single-valued range. For |
| instance, if LIMIT_VR is [0, 1], the predicate |
| VAR != [0, 1] does not mean that VAR's range is ~[0, 1]. |
| Rather, it means that for value 0 VAR should be ~[0, 0] |
| and for value 1, VAR should be ~[1, 1]. We cannot |
| represent these ranges. |
| |
| The only situation in which we can build a valid |
| anti-range is when LIMIT_VR is a single-valued range |
| (i.e., LIMIT_VR->MIN == LIMIT_VR->MAX). In that case, |
| build the anti-range ~[LIMIT_VR->MIN, LIMIT_VR->MAX]. */ |
| if (limit_vr |
| && limit_vr->type == VR_RANGE |
| && compare_values (limit_vr->min, limit_vr->max) == 0) |
| { |
| min = limit_vr->min; |
| max = limit_vr->max; |
| } |
| else |
| { |
| /* In any other case, we cannot use LIMIT's range to build a |
| valid anti-range. */ |
| min = max = limit; |
| } |
| |
| /* If MIN and MAX cover the whole range for their type, then |
| just use the original LIMIT. */ |
| if (INTEGRAL_TYPE_P (type) |
| && vrp_val_is_min (min) |
| && vrp_val_is_max (max)) |
| min = max = limit; |
| |
| set_value_range (vr_p, VR_ANTI_RANGE, min, max, vr_p->equiv); |
| } |
| else if (cond_code == LE_EXPR || cond_code == LT_EXPR) |
| { |
| min = TYPE_MIN_VALUE (type); |
| |
| if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE) |
| max = limit; |
| else |
| { |
| /* If LIMIT_VR is of the form [N1, N2], we need to build the |
| range [MIN, N2] for LE_EXPR and [MIN, N2 - 1] for |
| LT_EXPR. */ |
| max = limit_vr->max; |
| } |
| |
| /* If the maximum value forces us to be out of bounds, simply punt. |
| It would be pointless to try and do anything more since this |
| all should be optimized away above us. */ |
| if ((cond_code == LT_EXPR |
| && compare_values (max, min) == 0) |
| || is_overflow_infinity (max)) |
| set_value_range_to_varying (vr_p); |
| else |
| { |
| /* For LT_EXPR, we create the range [MIN, MAX - 1]. */ |
| if (cond_code == LT_EXPR) |
| { |
| tree one = build_int_cst (type, 1); |
| max = fold_build2 (MINUS_EXPR, type, max, one); |
| if (EXPR_P (max)) |
| TREE_NO_WARNING (max) = 1; |
| } |
| |
| set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv); |
| } |
| } |
| else if (cond_code == GE_EXPR || cond_code == GT_EXPR) |
| { |
| max = TYPE_MAX_VALUE (type); |
| |
| if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE) |
| min = limit; |
| else |
| { |
| /* If LIMIT_VR is of the form [N1, N2], we need to build the |
| range [N1, MAX] for GE_EXPR and [N1 + 1, MAX] for |
| GT_EXPR. */ |
| min = limit_vr->min; |
| } |
| |
| /* If the minimum value forces us to be out of bounds, simply punt. |
| It would be pointless to try and do anything more since this |
| all should be optimized away above us. */ |
| if ((cond_code == GT_EXPR |
| && compare_values (min, max) == 0) |
| || is_overflow_infinity (min)) |
| set_value_range_to_varying (vr_p); |
| else |
| { |
| /* For GT_EXPR, we create the range [MIN + 1, MAX]. */ |
| if (cond_code == GT_EXPR) |
| { |
| tree one = build_int_cst (type, 1); |
| min = fold_build2 (PLUS_EXPR, type, min, one); |
| if (EXPR_P (min)) |
| TREE_NO_WARNING (min) = 1; |
| } |
| |
| set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv); |
| } |
| } |
| else |
| gcc_unreachable (); |
| |
| /* If VAR already had a known range, it may happen that the new |
| range we have computed and VAR's range are not compatible. For |
| instance, |
| |
| if (p_5 == NULL) |
| p_6 = ASSERT_EXPR <p_5, p_5 == NULL>; |
| x_7 = p_6->fld; |
| p_8 = ASSERT_EXPR <p_6, p_6 != NULL>; |
| |
| While the above comes from a faulty program, it will cause an ICE |
| later because p_8 and p_6 will have incompatible ranges and at |
| the same time will be considered equivalent. A similar situation |
| would arise from |
| |
| if (i_5 > 10) |
| i_6 = ASSERT_EXPR <i_5, i_5 > 10>; |
| if (i_5 < 5) |
| i_7 = ASSERT_EXPR <i_6, i_6 < 5>; |
| |
| Again i_6 and i_7 will have incompatible ranges. It would be |
| pointless to try and do anything with i_7's range because |
| anything dominated by 'if (i_5 < 5)' will be optimized away. |
| Note, due to the wa in which simulation proceeds, the statement |
| i_7 = ASSERT_EXPR <...> we would never be visited because the |
| conditional 'if (i_5 < 5)' always evaluates to false. However, |
| this extra check does not hurt and may protect against future |
| changes to VRP that may get into a situation similar to the |
| NULL pointer dereference example. |
| |
| Note that these compatibility tests are only needed when dealing |
| with ranges or a mix of range and anti-range. If VAR_VR and VR_P |
| are both anti-ranges, they will always be compatible, because two |
| anti-ranges will always have a non-empty intersection. */ |
| |
| var_vr = get_value_range (var); |
| |
| /* We may need to make adjustments when VR_P and VAR_VR are numeric |
| ranges or anti-ranges. */ |
| if (vr_p->type == VR_VARYING |
| || vr_p->type == VR_UNDEFINED |
| || var_vr->type == VR_VARYING |
| || var_vr->type == VR_UNDEFINED |
| || symbolic_range_p (vr_p) |
| || symbolic_range_p (var_vr)) |
| return; |
| |
| if (var_vr->type == VR_RANGE && vr_p->type == VR_RANGE) |
| { |
| /* If the two ranges have a non-empty intersection, we can |
| refine the resulting range. Since the assert expression |
| creates an equivalency and at the same time it asserts a |
| predicate, we can take the intersection of the two ranges to |
| get better precision. */ |
| if (value_ranges_intersect_p (var_vr, vr_p)) |
| { |
| /* Use the larger of the two minimums. */ |
| if (compare_values (vr_p->min, var_vr->min) == -1) |
| min = var_vr->min; |
| else |
| min = vr_p->min; |
| |
| /* Use the smaller of the two maximums. */ |
| if (compare_values (vr_p->max, var_vr->max) == 1) |
| max = var_vr->max; |
| else |
| max = vr_p->max; |
| |
| set_value_range (vr_p, vr_p->type, min, max, vr_p->equiv); |
| } |
| else |
| { |
| /* The two ranges do not intersect, set the new range to |
| VARYING, because we will not be able to do anything |
| meaningful with it. */ |
| set_value_range_to_varying (vr_p); |
| } |
| } |
| else if ((var_vr->type == VR_RANGE && vr_p->type == VR_ANTI_RANGE) |
| || (var_vr->type == VR_ANTI_RANGE && vr_p->type == VR_RANGE)) |
| { |
| /* A range and an anti-range will cancel each other only if |
| their ends are the same. For instance, in the example above, |
| p_8's range ~[0, 0] and p_6's range [0, 0] are incompatible, |
| so VR_P should be set to VR_VARYING. */ |
| if (compare_values (var_vr->min, vr_p->min) == 0 |
| && compare_values (var_vr->max, vr_p->max) == 0) |
| set_value_range_to_varying (vr_p); |
| else |
| { |
| tree min, max, anti_min, anti_max, real_min, real_max; |
| |
| /* We want to compute the logical AND of the two ranges; |
| there are three cases to consider. |
| |
| |
| 1. The VR_ANTI_RANGE range is completely within the |
| VR_RANGE and the endpoints of the ranges are |
| different. In that case the resulting range |
| should be whichever range is more precise. |
| Typically that will be the VR_RANGE. |
| |
| 2. The VR_ANTI_RANGE is completely disjoint from |
| the VR_RANGE. In this case the resulting range |
| should be the VR_RANGE. |
| |
| 3. There is some overlap between the VR_ANTI_RANGE |
| and the VR_RANGE. |
| |
| 3a. If the high limit of the VR_ANTI_RANGE resides |
| within the VR_RANGE, then the result is a new |
| VR_RANGE starting at the high limit of the |
| the VR_ANTI_RANGE + 1 and extending to the |
| high limit of the original VR_RANGE. |
| |
| 3b. If the low limit of the VR_ANTI_RANGE resides |
| within the VR_RANGE, then the result is a new |
| VR_RANGE starting at the low limit of the original |
| VR_RANGE and extending to the low limit of the |
| VR_ANTI_RANGE - 1. */ |
| if (vr_p->type == VR_ANTI_RANGE) |
| { |
| anti_min = vr_p->min; |
| anti_max = vr_p->max; |
| real_min = var_vr->min; |
| real_max = var_vr->max; |
| } |
| else |
| { |
| anti_min = var_vr->min; |
| anti_max = var_vr->max; |
| real_min = vr_p->min; |
| real_max = vr_p->max; |
| } |
| |
| |
| /* Case 1, VR_ANTI_RANGE completely within VR_RANGE, |
| not including any endpoints. */ |
| if (compare_values (anti_max, real_max) == -1 |
| && compare_values (anti_min, real_min) == 1) |
| { |
| set_value_range (vr_p, VR_RANGE, real_min, |
| real_max, vr_p->equiv); |
| } |
| /* Case 2, VR_ANTI_RANGE completely disjoint from |
| VR_RANGE. */ |
| else if (compare_values (anti_min, real_max) == 1 |
| || compare_values (anti_max, real_min) == -1) |
| { |
| set_value_range (vr_p, VR_RANGE, real_min, |
| real_max, vr_p->equiv); |
| } |
| /* Case 3a, the anti-range extends into the low |
| part of the real range. Thus creating a new |
| low for the real range. */ |
| else if ((compare_values (anti_max, real_min) == 1 |
| || compare_values (anti_max, real_min) == 0) |
| && compare_values (anti_max, real_max) == -1) |
| { |
| gcc_assert (!is_positive_overflow_infinity (anti_max)); |
| if (needs_overflow_infinity (TREE_TYPE (anti_max)) |
| && vrp_val_is_max (anti_max)) |
| { |
| if (!supports_overflow_infinity (TREE_TYPE (var_vr->min))) |
| { |
| set_value_range_to_varying (vr_p); |
| return; |
| } |
| min = positive_overflow_infinity (TREE_TYPE (var_vr->min)); |
| } |
| else |
| min = fold_build2 (PLUS_EXPR, TREE_TYPE (var_vr->min), |
| anti_max, |
| build_int_cst (TREE_TYPE (var_vr->min), 1)); |
| max = real_max; |
| set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv); |
| } |
| /* Case 3b, the anti-range extends into the high |
| part of the real range. Thus creating a new |
| higher for the real range. */ |
| else if (compare_values (anti_min, real_min) == 1 |
| && (compare_values (anti_min, real_max) == -1 |
| || compare_values (anti_min, real_max) == 0)) |
| { |
| gcc_assert (!is_negative_overflow_infinity (anti_min)); |
| if (needs_overflow_infinity (TREE_TYPE (anti_min)) |
| && vrp_val_is_min (anti_min)) |
| { |
| if (!supports_overflow_infinity (TREE_TYPE (var_vr->min))) |
| { |
| set_value_range_to_varying (vr_p); |
| return; |
| } |
| max = negative_overflow_infinity (TREE_TYPE (var_vr->min)); |
| } |
| else |
| max = fold_build2 (MINUS_EXPR, TREE_TYPE (var_vr->min), |
| anti_min, |
| build_int_cst (TREE_TYPE (var_vr->min), 1)); |
| min = real_min; |
| set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv); |
| } |
| } |
| } |
| } |
| |
| |
| /* Extract range information from SSA name VAR and store it in VR. If |
| VAR has an interesting range, use it. Otherwise, create the |
| range [VAR, VAR] and return it. This is useful in situations where |
| we may have conditionals testing values of VARYING names. For |
| instance, |
| |
| x_3 = y_5; |
| if (x_3 > y_5) |
| ... |
| |
| Even if y_5 is deemed VARYING, we can determine that x_3 > y_5 is |
| always false. */ |
| |
| static void |
| extract_range_from_ssa_name (value_range_t *vr, tree var) |
| { |
| value_range_t *var_vr = get_value_range (var); |
| |
| if (var_vr->type != VR_UNDEFINED && var_vr->type != VR_VARYING) |
| copy_value_range (vr, var_vr); |
| else |
| set_value_range (vr, VR_RANGE, var, var, NULL); |
| |
| add_equivalence (vr->equiv, var); |
| } |
| |
| |
| /* Wrapper around int_const_binop. If the operation overflows and we |
| are not using wrapping arithmetic, then adjust the result to be |
| -INF or +INF depending on CODE, VAL1 and VAL2. This can return |
| NULL_TREE if we need to use an overflow infinity representation but |
| the type does not support it. */ |
| |
| static tree |
| vrp_int_const_binop (enum tree_code code, tree val1, tree val2) |
| { |
| tree res; |
| |
| res = int_const_binop (code, val1, val2, 0); |
| |
| /* If we are not using wrapping arithmetic, operate symbolically |
| on -INF and +INF. */ |
| if (TYPE_OVERFLOW_WRAPS (TREE_TYPE (val1))) |
| { |
| int checkz = compare_values (res, val1); |
| bool overflow = false; |
| |
| /* Ensure that res = val1 [+*] val2 >= val1 |
| or that res = val1 - val2 <= val1. */ |
| if ((code == PLUS_EXPR |
| && !(checkz == 1 || checkz == 0)) |
| || (code == MINUS_EXPR |
| && !(checkz == 0 || checkz == -1))) |
| { |
| overflow = true; |
| } |
| /* Checking for multiplication overflow is done by dividing the |
| output of the multiplication by the first input of the |
| multiplication. If the result of that division operation is |
| not equal to the second input of the multiplication, then the |
| multiplication overflowed. */ |
| else if (code == MULT_EXPR && !integer_zerop (val1)) |
| { |
| tree tmp = int_const_binop (TRUNC_DIV_EXPR, |
| res, |
| val1, 0); |
| int check = compare_values (tmp, val2); |
| |
| if (check != 0) |
| overflow = true; |
| } |
| |
| if (overflow) |
| { |
| res = copy_node (res); |
| TREE_OVERFLOW (res) = 1; |
| } |
| |
| } |
| else if ((TREE_OVERFLOW (res) |
| && !TREE_OVERFLOW (val1) |
| && !TREE_OVERFLOW (val2)) |
| || is_overflow_infinity (val1) |
| || is_overflow_infinity (val2)) |
| { |
| /* If the operation overflowed but neither VAL1 nor VAL2 are |
| overflown, return -INF or +INF depending on the operation |
| and the combination of signs of the operands. */ |
| int sgn1 = tree_int_cst_sgn (val1); |
| int sgn2 = tree_int_cst_sgn (val2); |
| |
| if (needs_overflow_infinity (TREE_TYPE (res)) |
| && !supports_overflow_infinity (TREE_TYPE (res))) |
| return NULL_TREE; |
| |
| /* We have to punt on adding infinities of different signs, |
| since we can't tell what the sign of the result should be. |
| Likewise for subtracting infinities of the same sign. */ |
| if (((code == PLUS_EXPR && sgn1 != sgn2) |
| || (code == MINUS_EXPR && sgn1 == sgn2)) |
| && is_overflow_infinity (val1) |
| && is_overflow_infinity (val2)) |
| return NULL_TREE; |
| |
| /* Don't try to handle division or shifting of infinities. */ |
| if ((code == TRUNC_DIV_EXPR |
| || code == FLOOR_DIV_EXPR |
| || code == CEIL_DIV_EXPR |
| || code == EXACT_DIV_EXPR |
| || code == ROUND_DIV_EXPR |
| || code == RSHIFT_EXPR) |
| && (is_overflow_infinity (val1) |
| || is_overflow_infinity (val2))) |
| return NULL_TREE; |
| |
| /* Notice that we only need to handle the restricted set of |
| operations handled by extract_range_from_binary_expr. |
| Among them, only multiplication, addition and subtraction |
| can yield overflow without overflown operands because we |
| are working with integral types only... except in the |
| case VAL1 = -INF and VAL2 = -1 which overflows to +INF |
| for division too. */ |
| |
| /* For multiplication, the sign of the overflow is given |
| by the comparison of the signs of the operands. */ |
| if ((code == MULT_EXPR && sgn1 == sgn2) |
| /* For addition, the operands must be of the same sign |
| to yield an overflow. Its sign is therefore that |
| of one of the operands, for example the first. For |
| infinite operands X + -INF is negative, not positive. */ |
| || (code == PLUS_EXPR |
| && (sgn1 >= 0 |
| ? !is_negative_overflow_infinity (val2) |
| : is_positive_overflow_infinity (val2))) |
| /* For subtraction, non-infinite operands must be of |
| different signs to yield an overflow. Its sign is |
| therefore that of the first operand or the opposite of |
| that of the second operand. A first operand of 0 counts |
| as positive here, for the corner case 0 - (-INF), which |
| overflows, but must yield +INF. For infinite operands 0 |
| - INF is negative, not positive. */ |
| || (code == MINUS_EXPR |
| && (sgn1 >= 0 |
| ? !is_positive_overflow_infinity (val2) |
| : is_negative_overflow_infinity (val2))) |
| /* For division, the only case is -INF / -1 = +INF. */ |
| || code == TRUNC_DIV_EXPR |
| || code == FLOOR_DIV_EXPR |
| || code == CEIL_DIV_EXPR |
| || code == EXACT_DIV_EXPR |
| || code == ROUND_DIV_EXPR) |
| return (needs_overflow_infinity (TREE_TYPE (res)) |
| ? positive_overflow_infinity (TREE_TYPE (res)) |
| : TYPE_MAX_VALUE (TREE_TYPE (res))); |
| else |
| return (needs_overflow_infinity (TREE_TYPE (res)) |
| ? negative_overflow_infinity (TREE_TYPE (res)) |
| : TYPE_MIN_VALUE (TREE_TYPE (res))); |
| } |
| |
| return res; |
| } |
| |
| |
| /* Extract range information from a binary expression EXPR based on |
| the ranges of each of its operands and the expression code. */ |
| |
| static void |
| extract_range_from_binary_expr (value_range_t *vr, tree expr) |
| { |
| enum tree_code code = TREE_CODE (expr); |
| enum value_range_type type; |
| tree op0, op1, min, max; |
| int cmp; |
| value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL }; |
| value_range_t vr1 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL }; |
| |
| /* Not all binary expressions can be applied to ranges in a |
| meaningful way. Handle only arithmetic operations. */ |
| if (code != PLUS_EXPR |
| && code != MINUS_EXPR |
| && code != MULT_EXPR |
| && code != TRUNC_DIV_EXPR |
| && code != FLOOR_DIV_EXPR |
| && code != CEIL_DIV_EXPR |
| && code != EXACT_DIV_EXPR |
| && code != ROUND_DIV_EXPR |
| && code != MIN_EXPR |
| && code != MAX_EXPR |
| && code != BIT_AND_EXPR |
| && code != TRUTH_ANDIF_EXPR |
| && code != TRUTH_ORIF_EXPR |
| && code != TRUTH_AND_EXPR |
| && code != TRUTH_OR_EXPR) |
| { |
| set_value_range_to_varying (vr); |
| return; |
| } |
| |
| /* Get value ranges for each operand. For constant operands, create |
| a new value range with the operand to simplify processing. */ |
| op0 = TREE_OPERAND (expr, 0); |
| if (TREE_CODE (op0) == SSA_NAME) |
| vr0 = *(get_value_range (op0)); |
| else if (is_gimple_min_invariant (op0)) |
| set_value_range_to_value (&vr0, op0, NULL); |
| else |
| set_value_range_to_varying (&vr0); |
| |
| op1 = TREE_OPERAND (expr, 1); |
| if (TREE_CODE (op1) == SSA_NAME) |
| vr1 = *(get_value_range (op1)); |
| else if (is_gimple_min_invariant (op1)) |
| set_value_range_to_value (&vr1, op1, NULL); |
| else |
| set_value_range_to_varying (&vr1); |
| |
| /* If either range is UNDEFINED, so is the result. */ |
| if (vr0.type == VR_UNDEFINED || vr1.type == VR_UNDEFINED) |
| { |
| set_value_range_to_undefined (vr); |
| return; |
| } |
| |
| /* The type of the resulting value range defaults to VR0.TYPE. */ |
| type = vr0.type; |
| |
| /* Refuse to operate on VARYING ranges, ranges of different kinds |
| and symbolic ranges. As an exception, we allow BIT_AND_EXPR |
| because we may be able to derive a useful range even if one of |
| the operands is VR_VARYING or symbolic range. TODO, we may be |
| able to derive anti-ranges in some cases. */ |
| if (code != BIT_AND_EXPR |
| && code != TRUTH_AND_EXPR |
| && code != TRUTH_OR_EXPR |
| && (vr0.type == VR_VARYING |
| || vr1.type == VR_VARYING |
| || vr0.type != vr1.type |
| || symbolic_range_p (&vr0) |
| || symbolic_range_p (&vr1))) |
| { |
| set_value_range_to_varying (vr); |
| return; |
| } |
| |
| /* Now evaluate the expression to determine the new range. */ |
| if (POINTER_TYPE_P (TREE_TYPE (expr)) |
| || POINTER_TYPE_P (TREE_TYPE (op0)) |
| || POINTER_TYPE_P (TREE_TYPE (op1))) |
| { |
| /* For pointer types, we are really only interested in asserting |
| whether the expression evaluates to non-NULL. FIXME, we used |
| to gcc_assert (code == PLUS_EXPR || code == MINUS_EXPR), but |
| ivopts is generating expressions with pointer multiplication |
| in them. */ |
| if (code == PLUS_EXPR) |
| { |
| if (range_is_nonnull (&vr0) || range_is_nonnull (&vr1)) |
| set_value_range_to_nonnull (vr, TREE_TYPE (expr)); |
| else if (range_is_null (&vr0) && range_is_null (&vr1)) |
| set_value_range_to_null (vr, TREE_TYPE (expr)); |
| else |
| set_value_range_to_varying (vr); |
| } |
| else |
| { |
| /* Subtracting from a pointer, may yield 0, so just drop the |
| resulting range to varying. */ |
| set_value_range_to_varying (vr); |
| } |
| |
| return; |
| } |
| |
| /* For integer ranges, apply the operation to each end of the |
| range and see what we end up with. */ |
| if (code == TRUTH_ANDIF_EXPR |
| || code == TRUTH_ORIF_EXPR |
| || code == TRUTH_AND_EXPR |
| || code == TRUTH_OR_EXPR) |
| { |
| /* If one of the operands is zero, we know that the whole |
| expression evaluates zero. */ |
| if (code == TRUTH_AND_EXPR |
| && ((vr0.type == VR_RANGE |
| && integer_zerop (vr0.min) |
| && integer_zerop (vr0.max)) |
| || (vr1.type == VR_RANGE |
| && integer_zerop (vr1.min) |
| && integer_zerop (vr1.max)))) |
| { |
| type = VR_RANGE; |
| min = max = build_int_cst (TREE_TYPE (expr), 0); |
| } |
| /* If one of the operands is one, we know that the whole |
| expression evaluates one. */ |
| else if (code == TRUTH_OR_EXPR |
| && ((vr0.type == VR_RANGE |
| && integer_onep (vr0.min) |
| && integer_onep (vr0.max)) |
| || (vr1.type == VR_RANGE |
| && integer_onep (vr1.min) |
| && integer_onep (vr1.max)))) |
| { |
| type = VR_RANGE; |
| min = max = build_int_cst (TREE_TYPE (expr), 1); |
| } |
| else if (vr0.type != VR_VARYING |
| && vr1.type != VR_VARYING |
| && vr0.type == vr1.type |
| && !symbolic_range_p (&vr0) |
| && !overflow_infinity_range_p (&vr0) |
| && !symbolic_range_p (&vr1) |
| && !overflow_infinity_range_p (&vr1)) |
| { |
| /* Boolean expressions cannot be folded with int_const_binop. */ |
| min = fold_binary (code, TREE_TYPE (expr), vr0.min, vr1.min); |
| max = fold_binary (code, TREE_TYPE (expr), vr0.max, vr1.max); |
| } |
| else |
| { |
| set_value_range_to_varying (vr); |
| return; |
| } |
| } |
| else if (code == PLUS_EXPR |
| || code == MIN_EXPR |
| || code == MAX_EXPR) |
| { |
| /* If we have a PLUS_EXPR with two VR_ANTI_RANGEs, drop to |
| VR_VARYING. It would take more effort to compute a precise |
| range for such a case. For example, if we have op0 == 1 and |
| op1 == -1 with their ranges both being ~[0,0], we would have |
| op0 + op1 == 0, so we cannot claim that the sum is in ~[0,0]. |
| Note that we are guaranteed to have vr0.type == vr1.type at |
| this point. */ |
| if (code == PLUS_EXPR && vr0.type == VR_ANTI_RANGE) |
| { |
| set_value_range_to_varying (vr); |
| return; |
| } |
| |
| /* For operations that make the resulting range directly |
| proportional to the original ranges, apply the operation to |
| the same end of each range. */ |
| min = vrp_int_const_binop (code, vr0.min, vr1.min); |
| max = vrp_int_const_binop (code, vr0.max, vr1.max); |
| } |
| else if (code == MULT_EXPR |
| || code == TRUNC_DIV_EXPR |
| || code == FLOOR_DIV_EXPR |
| || code == CEIL_DIV_EXPR |
| || code == EXACT_DIV_EXPR |
| || code == ROUND_DIV_EXPR) |
| { |
| tree val[4]; |
| size_t i; |
| bool sop; |
| |
| /* If we have an unsigned MULT_EXPR with two VR_ANTI_RANGEs, |
| drop to VR_VARYING. It would take more effort to compute a |
| precise range for such a case. For example, if we have |
| op0 == 65536 and op1 == 65536 with their ranges both being |
| ~[0,0] on a 32-bit machine, we would have op0 * op1 == 0, so |
| we cannot claim that the product is in ~[0,0]. Note that we |
| are guaranteed to have vr0.type == vr1.type at this |
| point. */ |
| if (code == MULT_EXPR |
| && vr0.type == VR_ANTI_RANGE |
| && !TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (op0))) |
| { |
| set_value_range_to_varying (vr); |
| return; |
| } |
| |
| /* Multiplications and divisions are a bit tricky to handle, |
| depending on the mix of signs we have in the two ranges, we |
| need to operate on different values to get the minimum and |
| maximum values for the new range. One approach is to figure |
| out all the variations of range combinations and do the |
| operations. |
| |
| However, this involves several calls to compare_values and it |
| is pretty convoluted. It's simpler to do the 4 operations |
| (MIN0 OP MIN1, MIN0 OP MAX1, MAX0 OP MIN1 and MAX0 OP MAX0 OP |
| MAX1) and then figure the smallest and largest values to form |
| the new range. */ |
| |
| /* Divisions by zero result in a VARYING value. */ |
| if (code != MULT_EXPR |
| && (vr0.type == VR_ANTI_RANGE || range_includes_zero_p (&vr1))) |
| { |
| set_value_range_to_varying (vr); |
| return; |
| } |
| |
| /* Compute the 4 cross operations. */ |
| sop = false; |
| val[0] = vrp_int_const_binop (code, vr0.min, vr1.min); |
| if (val[0] == NULL_TREE) |
| sop = true; |
| |
| if (vr1.max == vr1.min) |
| val[1] = NULL_TREE; |
| else |
| { |
| val[1] = vrp_int_const_binop (code, vr0.min, vr1.max); |
| if (val[1] == NULL_TREE) |
| sop = true; |
| } |
| |
| if (vr0.max == vr0.min) |
| val[2] = NULL_TREE; |
| else |
| { |
| val[2] = vrp_int_const_binop (code, vr0.max, vr1.min); |
| if (val[2] == NULL_TREE) |
| sop = true; |
| } |
| |
| if (vr0.min == vr0.max || vr1.min == vr1.max) |
| val[3] = NULL_TREE; |
| else |
| { |
| val[3] = vrp_int_const_binop (code, vr0.max, vr1.max); |
| if (val[3] == NULL_TREE) |
| sop = true; |
| } |
| |
| if (sop) |
| { |
| set_value_range_to_varying (vr); |
| return; |
| } |
| |
| /* Set MIN to the minimum of VAL[i] and MAX to the maximum |
| of VAL[i]. */ |
| min = val[0]; |
| max = val[0]; |
| for (i = 1; i < 4; i++) |
| { |
| if (!is_gimple_min_invariant (min) |
| || (TREE_OVERFLOW (min) && !is_overflow_infinity (min)) |
| || !is_gimple_min_invariant (max) |
| || (TREE_OVERFLOW (max) && !is_overflow_infinity (max))) |
| break; |
| |
| if (val[i]) |
| { |
| if (!is_gimple_min_invariant (val[i]) |
| || (TREE_OVERFLOW (val[i]) |
| && !is_overflow_infinity (val[i]))) |
| { |
| /* If we found an overflowed value, set MIN and MAX |
| to it so that we set the resulting range to |
| VARYING. */ |
| min = max = val[i]; |
| break; |
| } |
| |
| if (compare_values (val[i], min) == -1) |
| min = val[i]; |
| |
| if (compare_values (val[i], max) == 1) |
| max = val[i]; |
| } |
| } |
| } |
| else if (code == MINUS_EXPR) |
| { |
| /* If we have a MINUS_EXPR with two VR_ANTI_RANGEs, drop to |
| VR_VARYING. It would take more effort to compute a precise |
| range for such a case. For example, if we have op0 == 1 and |
| op1 == 1 with their ranges both being ~[0,0], we would have |
| op0 - op1 == 0, so we cannot claim that the difference is in |
| ~[0,0]. Note that we are guaranteed to have |
| vr0.type == vr1.type at this point. */ |
| if (vr0.type == VR_ANTI_RANGE) |
| { |
| set_value_range_to_varying (vr); |
| return; |
| } |
| |
| /* For MINUS_EXPR, apply the operation to the opposite ends of |
| each range. */ |
| min = vrp_int_const_binop (code, vr0.min, vr1.max); |
| max = vrp_int_const_binop (code, vr0.max, vr1.min); |
| } |
| else if (code == BIT_AND_EXPR) |
| { |
| if (vr0.type == VR_RANGE |
| && vr0.min == vr0.max |
| && TREE_CODE (vr0.max) == INTEGER_CST |
| && !TREE_OVERFLOW (vr0.max) |
| && tree_int_cst_sgn (vr0.max) >= 0) |
| { |
| min = build_int_cst (TREE_TYPE (expr), 0); |
| max = vr0.max; |
| } |
| else if (vr1.type == VR_RANGE |
| && vr1.min == vr1.max |
| && TREE_CODE (vr1.max) == INTEGER_CST |
| && !TREE_OVERFLOW (vr1.max) |
| && tree_int_cst_sgn (vr1.max) >= 0) |
| { |
| type = VR_RANGE; |
| min = build_int_cst (TREE_TYPE (expr), 0); |
| max = vr1.max; |
| } |
| else |
| { |
| set_value_range_to_varying (vr); |
| return; |
| } |
| } |
| else |
| gcc_unreachable (); |
| |
| /* If either MIN or MAX overflowed, then set the resulting range to |
| VARYING. But we do accept an overflow infinity |
| representation. */ |
| if (min == NULL_TREE |
| || !is_gimple_min_invariant (min) |
| || (TREE_OVERFLOW (min) && !is_overflow_infinity (min)) |
| || max == NULL_TREE |
| || !is_gimple_min_invariant (max) |
| || (TREE_OVERFLOW (max) && !is_overflow_infinity (max))) |
| { |
| set_value_range_to_varying (vr); |
| return; |
| } |
| |
| /* We punt if: |
| 1) [-INF, +INF] |
| 2) [-INF, +-INF(OVF)] |
| 3) [+-INF(OVF), +INF] |
| 4) [+-INF(OVF), +-INF(OVF)] |
| We learn nothing when we have INF and INF(OVF) on both sides. |
| Note that we do accept [-INF, -INF] and [+INF, +INF] without |
| overflow. */ |
| if ((vrp_val_is_min (min) || is_overflow_infinity (min)) |
| && (vrp_val_is_max (max) || is_overflow_infinity (max))) |
| { |
| set_value_range_to_varying (vr); |
| return; |
| } |
| |
| cmp = compare_values (min, max); |
| if (cmp == -2 || cmp == 1) |
| { |
| /* If the new range has its limits swapped around (MIN > MAX), |
| then the operation caused one of them to wrap around, mark |
| the new range VARYING. */ |
| set_value_range_to_varying (vr); |
| } |
| else |
| set_value_range (vr, type, min, max, NULL); |
| } |
| |
| |
| /* Extract range information from a unary expression EXPR based on |
| the range of its operand and the expression code. */ |
| |
| static void |
| extract_range_from_unary_expr (value_range_t *vr, tree expr) |
| { |
| enum tree_code code = TREE_CODE (expr); |
| tree min, max, op0; |
| int cmp; |
| value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL }; |
| |
| /* Refuse to operate on certain unary expressions for which we |
| cannot easily determine a resulting range. */ |
| if (code == FIX_TRUNC_EXPR |
| || code == FIX_CEIL_EXPR |
| || code == FIX_FLOOR_EXPR |
| || code == FIX_ROUND_EXPR |
| || code == FLOAT_EXPR |
| || code == BIT_NOT_EXPR |
| || code == NON_LVALUE_EXPR |
| || code == CONJ_EXPR) |
| { |
| set_value_range_to_varying (vr); |
| return; |
| } |
| |
| /* Get value ranges for the operand. For constant operands, create |
| a new value range with the operand to simplify processing. */ |
| op0 = TREE_OPERAND (expr, 0); |
| if (TREE_CODE (op0) == SSA_NAME) |
| vr0 = *(get_value_range (op0)); |
| else if (is_gimple_min_invariant (op0)) |
| set_value_range_to_value (&vr0, op0, NULL); |
| else |
| set_value_range_to_varying (&vr0); |
| |
| /* If VR0 is UNDEFINED, so is the result. */ |
| if (vr0.type == VR_UNDEFINED) |
| { |
| set_value_range_to_undefined (vr); |
| return; |
| } |
| |
| /* Refuse to operate on symbolic ranges, or if neither operand is |
| a pointer or integral type. */ |
| if ((!INTEGRAL_TYPE_P (TREE_TYPE (op0)) |
| && !POINTER_TYPE_P (TREE_TYPE (op0))) |
| || (vr0.type != VR_VARYING |
| && symbolic_range_p (&vr0))) |
| { |
| set_value_range_to_varying (vr); |
| return; |
| } |
| |
| /* If the expression involves pointers, we are only interested in |
| determining if it evaluates to NULL [0, 0] or non-NULL (~[0, 0]). */ |
| if (POINTER_TYPE_P (TREE_TYPE (expr)) || POINTER_TYPE_P (TREE_TYPE (op0))) |
| { |
| bool sop; |
| |
| sop = false; |
| if (range_is_nonnull (&vr0) |
| || (tree_expr_nonzero_warnv_p (expr, &sop) |
| && !sop)) |
| set_value_range_to_nonnull (vr, TREE_TYPE (expr)); |
| else if (range_is_null (&vr0)) |
| set_value_range_to_null (vr, TREE_TYPE (expr)); |
| else |
| set_value_range_to_varying (vr); |
| |
| return; |
| } |
| |
| /* Handle unary expressions on integer ranges. */ |
| if (code == NOP_EXPR || code == CONVERT_EXPR) |
| { |
| tree inner_type = TREE_TYPE (op0); |
| tree outer_type = TREE_TYPE (expr); |
| |
| /* If VR0 represents a simple range, then try to convert |
| the min and max values for the range to the same type |
| as OUTER_TYPE. If the results compare equal to VR0's |
| min and max values and the new min is still less than |
| or equal to the new max, then we can safely use the newly |
| computed range for EXPR. This allows us to compute |
| accurate ranges through many casts. */ |
| if ((vr0.type == VR_RANGE |
| && !overflow_infinity_range_p (&vr0)) |
| || (vr0.type == VR_VARYING |
| && TYPE_PRECISION (outer_type) > TYPE_PRECISION (inner_type))) |
| { |
| tree new_min, new_max, orig_min, orig_max; |
| |
| /* Convert the input operand min/max to OUTER_TYPE. If |
| the input has no range information, then use the min/max |
| for the input's type. */ |
| if (vr0.type == VR_RANGE) |
| { |
| orig_min = vr0.min; |
| orig_max = vr0.max; |
| } |
| else |
| { |
| orig_min = TYPE_MIN_VALUE (inner_type); |
| orig_max = TYPE_MAX_VALUE (inner_type); |
| } |
| |
| new_min = fold_convert (outer_type, orig_min); |
| new_max = fold_convert (outer_type, orig_max); |
| |
| /* Verify the new min/max values are gimple values and |
| that they compare equal to the original input's |
| min/max values. */ |
| if (is_gimple_val (new_min) |
| && is_gimple_val (new_max) |
| && tree_int_cst_equal (new_min, orig_min) |
| && tree_int_cst_equal (new_max, orig_max) |
| && (!is_overflow_infinity (new_min) |
| || !is_overflow_infinity (new_max)) |
| && compare_values (new_min, new_max) <= 0 |
| && compare_values (new_min, new_max) >= -1) |
| { |
| set_value_range (vr, VR_RANGE, new_min, new_max, vr->equiv); |
| return; |
| } |
| } |
| |
| /* When converting types of different sizes, set the result to |
| VARYING. Things like sign extensions and precision loss may |
| change the range. For instance, if x_3 is of type 'long long |
| int' and 'y_5 = (unsigned short) x_3', if x_3 is ~[0, 0], it |
| is impossible to know at compile time whether y_5 will be |
| ~[0, 0]. */ |
| if (TYPE_SIZE (inner_type) != TYPE_SIZE (outer_type) |
| || TYPE_PRECISION (inner_type) != TYPE_PRECISION (outer_type)) |
| { |
| set_value_range_to_varying (vr); |
| return; |
| } |
| } |
| |
| /* Conversion of a VR_VARYING value to a wider type can result |
| in a usable range. So wait until after we've handled conversions |
| before dropping the result to VR_VARYING if we had a source |
| operand that is VR_VARYING. */ |
| if (vr0.type == VR_VARYING) |
| { |
| set_value_range_to_varying (vr); |
| return; |
| } |
| |
| /* Apply the operation to each end of the range and see what we end |
| up with. */ |
| if (code == NEGATE_EXPR |
| && !TYPE_UNSIGNED (TREE_TYPE (expr))) |
| { |
| /* NEGATE_EXPR flips the range around. We need to treat |
| TYPE_MIN_VALUE specially. */ |
| if (is_positive_overflow_infinity (vr0.max)) |
| min = negative_overflow_infinity (TREE_TYPE (expr)); |
| else if (is_negative_overflow_infinity (vr0.max)) |
| min = positive_overflow_infinity (TREE_TYPE (expr)); |
| else if (!vrp_val_is_min (vr0.max)) |
| min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max); |
| else if (needs_overflow_infinity (TREE_TYPE (expr))) |
| { |
| if (supports_overflow_infinity (TREE_TYPE (expr)) |
| && !is_overflow_infinity (vr0.min) |
| && !vrp_val_is_min (vr0.min)) |
| min = positive_overflow_infinity (TREE_TYPE (expr)); |
| else |
| { |
| set_value_range_to_varying (vr); |
| return; |
| } |
| } |
| else |
| min = TYPE_MIN_VALUE (TREE_TYPE (expr)); |
| |
| if (is_positive_overflow_infinity (vr0.min)) |
| max = negative_overflow_infinity (TREE_TYPE (expr)); |
| else if (is_negative_overflow_infinity (vr0.min)) |
| max = positive_overflow_infinity (TREE_TYPE (expr)); |
| else if (!vrp_val_is_min (vr0.min)) |
| max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min); |
| else if (needs_overflow_infinity (TREE_TYPE (expr))) |
| { |
| if (supports_overflow_infinity (TREE_TYPE (expr))) |
| max = positive_overflow_infinity (TREE_TYPE (expr)); |
| else |
| { |
| set_value_range_to_varying (vr); |
| return; |
| } |
| } |
| else |
| max = TYPE_MIN_VALUE (TREE_TYPE (expr)); |
| } |
| else if (code == NEGATE_EXPR |
| && TYPE_UNSIGNED (TREE_TYPE (expr))) |
| { |
| if (!range_includes_zero_p (&vr0)) |
| { |
| max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min); |
| min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max); |
| } |
| else |
| { |
| if (range_is_null (&vr0)) |
| set_value_range_to_null (vr, TREE_TYPE (expr)); |
| else |
| set_value_range_to_varying (vr); |
| return; |
| } |
| } |
| else if (code == ABS_EXPR |
| && !TYPE_UNSIGNED (TREE_TYPE (expr))) |
| { |
| /* -TYPE_MIN_VALUE = TYPE_MIN_VALUE with flag_wrapv so we can't get a |
| useful range. */ |
| if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (expr)) |
| && ((vr0.type == VR_RANGE |
| && vrp_val_is_min (vr0.min)) |
| || (vr0.type == VR_ANTI_RANGE |
| && !vrp_val_is_min (vr0.min) |
| && !range_includes_zero_p (&vr0)))) |
| { |
| set_value_range_to_varying (vr); |
| return; |
| } |
| |
| /* ABS_EXPR may flip the range around, if the original range |
| included negative values. */ |
| if (is_overflow_infinity (vr0.min)) |
| min = positive_overflow_infinity (TREE_TYPE (expr)); |
| else if (!vrp_val_is_min (vr0.min)) |
| min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min); |
| else if (!needs_overflow_infinity (TREE_TYPE (expr))) |
| min = TYPE_MAX_VALUE (TREE_TYPE (expr)); |
| else if (supports_overflow_infinity (TREE_TYPE (expr))) |
| min = positive_overflow_infinity (TREE_TYPE (expr)); |
| else |
| { |
| set_value_range_to_varying (vr); |
| return; |
| } |
| |
| if (is_overflow_infinity (vr0.max)) |
| max = positive_overflow_infinity (TREE_TYPE (expr)); |
| else if (!vrp_val_is_min (vr0.max)) |
| max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max); |
| else if (!needs_overflow_infinity (TREE_TYPE (expr))) |
| max = TYPE_MAX_VALUE (TREE_TYPE (expr)); |
| else if (supports_overflow_infinity (TREE_TYPE (expr))) |
| max = positive_overflow_infinity (TREE_TYPE (expr)); |
| else |
| { |
| set_value_range_to_varying (vr); |
| return; |
| } |
| |
| cmp = compare_values (min, max); |
| |
| /* If a VR_ANTI_RANGEs contains zero, then we have |
| ~[-INF, min(MIN, MAX)]. */ |
| if (vr0.type == VR_ANTI_RANGE) |
| { |
| if (range_includes_zero_p (&vr0)) |
| { |
| /* Take the lower of the two values. */ |
| if (cmp != 1) |
| max = min; |
| |
| /* Create ~[-INF, min (abs(MIN), abs(MAX))] |
| or ~[-INF + 1, min (abs(MIN), abs(MAX))] when |
| flag_wrapv is set and the original anti-range doesn't include |
| TYPE_MIN_VALUE, remember -TYPE_MIN_VALUE = TYPE_MIN_VALUE. */ |
| if (TYPE_OVERFLOW_WRAPS (TREE_TYPE (expr))) |
| { |
| tree type_min_value = TYPE_MIN_VALUE (TREE_TYPE (expr)); |
| |
| min = (vr0.min != type_min_value |
| ? int_const_binop (PLUS_EXPR, type_min_value, |
| integer_one_node, 0) |
| : type_min_value); |
| } |
| else |
| { |
| if (overflow_infinity_range_p (&vr0)) |
| min = negative_overflow_infinity (TREE_TYPE (expr)); |
| else |
| min = TYPE_MIN_VALUE (TREE_TYPE (expr)); |
| } |
| } |
| else |
| { |
| /* All else has failed, so create the range [0, INF], even for |
| flag_wrapv since TYPE_MIN_VALUE is in the original |
| anti-range. */ |
| vr0.type = VR_RANGE; |
| min = build_int_cst (TREE_TYPE (expr), 0); |
| if (needs_overflow_infinity (TREE_TYPE (expr))) |
| { |
| if (supports_overflow_infinity (TREE_TYPE (expr))) |
| max = positive_overflow_infinity (TREE_TYPE (expr)); |
| else |
| { |
| set_value_range_to_varying (vr); |
| return; |
| } |
| } |
| else |
| max = TYPE_MAX_VALUE (TREE_TYPE (expr)); |
| } |
| } |
| |
| /* If the range contains zero then we know that the minimum value in the |
| range will be zero. */ |
| else if (range_includes_zero_p (&vr0)) |
| { |
| if (cmp == 1) |
| max = min; |
| min = build_int_cst (TREE_TYPE (expr), 0); |
| } |
| else |
| { |
| /* If the range was reversed, swap MIN and MAX. */ |
| if (cmp == 1) |
| { |
| tree t = min; |
| min = max; |
| max = t; |
| } |
| } |
| } |
| else |
| { |
| /* Otherwise, operate on each end of the range. */ |
| min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min); |
| max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max); |
| |
| if (needs_overflow_infinity (TREE_TYPE (expr))) |
| { |
| gcc_assert (code != NEGATE_EXPR && code != ABS_EXPR); |
| |
| /* If both sides have overflowed, we don't know |
| anything. */ |
| if ((is_overflow_infinity (vr0.min) |
| || TREE_OVERFLOW (min)) |
| && (is_overflow_infinity (vr0.max) |
| || TREE_OVERFLOW (max))) |
| { |
| set_value_range_to_varying (vr); |
| return; |
| } |
| |
| if (is_overflow_infinity (vr0.min)) |
| min = vr0.min; |
| else if (TREE_OVERFLOW (min)) |
| { |
| if (supports_overflow_infinity (TREE_TYPE (expr))) |
| min = (tree_int_cst_sgn (min) >= 0 |
| ? positive_overflow_infinity (TREE_TYPE (min)) |
| : negative_overflow_infinity (TREE_TYPE (min))); |
| else |
| { |
| set_value_range_to_varying (vr); |
| return; |
| } |
| } |
| |
| if (is_overflow_infinity (vr0.max)) |
| max = vr0.max; |
| else if (TREE_OVERFLOW (max)) |
| { |
| if (supports_overflow_infinity (TREE_TYPE (expr))) |
| max = (tree_int_cst_sgn (max) >= 0 |
| ? positive_overflow_infinity (TREE_TYPE (max)) |
| : negative_overflow_infinity (TREE_TYPE (max))); |
| else |
| { |
| set_value_range_to_varying (vr); |
| return; |
| } |
| } |
| } |
| } |
| |
| cmp = compare_values (min, max); |
| if (cmp == -2 || cmp == 1) |
| { |
| /* If the new range has its limits swapped around (MIN > MAX), |
| then the operation caused one of them to wrap around, mark |
| the new range VARYING. */ |
| set_value_range_to_varying (vr); |
| } |
| else |
| set_value_range (vr, vr0.type, min, max, NULL); |
| } |
| |
| |
| /* Extract range information from a comparison expression EXPR based |
| on the range of its operand and the expression code. */ |
| |
| static void |
| extract_range_from_comparison (value_range_t *vr, tree expr) |
| { |
| bool sop = false; |
| tree val = vrp_evaluate_conditional_warnv (expr, false, &sop); |
| |
| /* A disadvantage of using a special infinity as an overflow |
| representation is that we lose the ability to record overflow |
| when we don't have an infinity. So we have to ignore a result |
| which relies on overflow. */ |
| |
| if (val && !is_overflow_infinity (val) && !sop) |
| { |
| /* Since this expression was found on the RHS of an assignment, |
| its type may be different from _Bool. Convert VAL to EXPR's |
| type. */ |
| val = fold_convert (TREE_TYPE (expr), val); |
| if (is_gimple_min_invariant (val)) |
| set_value_range_to_value (vr, val, vr->equiv); |
| else |
| set_value_range (vr, VR_RANGE, val, val, vr->equiv); |
| } |
| else |
| set_value_range_to_varying (vr); |
| } |
| |
| |
| /* Try to compute a useful range out of expression EXPR and store it |
| in *VR. */ |
| |
| static void |
| extract_range_from_expr (value_range_t *vr, tree expr) |
| { |
| enum tree_code code = TREE_CODE (expr); |
| |
| if (code == ASSERT_EXPR) |
| extract_range_from_assert (vr, expr); |
| else if (code == SSA_NAME) |
| extract_range_from_ssa_name (vr, expr); |
| else if (TREE_CODE_CLASS (code) == tcc_binary |
| || code == TRUTH_ANDIF_EXPR |
| || code == TRUTH_ORIF_EXPR |
| || code == TRUTH_AND_EXPR |
| || code == TRUTH_OR_EXPR |
| || code == TRUTH_XOR_EXPR) |
| extract_range_from_binary_expr (vr, expr); |
| else if (TREE_CODE_CLASS (code) == tcc_unary) |
| extract_range_from_unary_expr (vr, expr); |
| else if (TREE_CODE_CLASS (code) == tcc_comparison) |
| extract_range_from_comparison (vr, expr); |
| else if (is_gimple_min_invariant (expr)) |
| set_value_range_to_value (vr, expr, NULL); |
| else |
| set_value_range_to_varying (vr); |
| |
| /* If we got a varying range from the tests above, try a final |
| time to derive a nonnegative or nonzero range. This time |
| relying primarily on generic routines in fold in conjunction |
| with range data. */ |
| if (vr->type == VR_VARYING) |
| { |
| bool sop = false; |
| |
| if (INTEGRAL_TYPE_P (TREE_TYPE (expr)) |
| && vrp_expr_computes_nonnegative (expr, &sop)) |
| set_value_range_to_nonnegative (vr, TREE_TYPE (expr), |
| sop || is_overflow_infinity (expr)); |
| else if (vrp_expr_computes_nonzero (expr, &sop) |
| && !sop) |
| set_value_range_to_nonnull (vr, TREE_TYPE (expr)); |
| } |
| } |
| |
| /* Given a range VR, a LOOP and a variable VAR, determine whether it |
| would be profitable to adjust VR using scalar evolution information |
| for VAR. If so, update VR with the new limits. */ |
| |
| static void |
| adjust_range_with_scev (value_range_t *vr, struct loop *loop, tree stmt, |
| tree var) |
| { |
| tree init, step, chrec, tmin, tmax, min, max, type; |
| enum ev_direction dir; |
| |
| /* TODO. Don't adjust anti-ranges. An anti-range may provide |
| better opportunities than a regular range, but I'm not sure. */ |
| if (vr->type == VR_ANTI_RANGE) |
| return; |
| |
| chrec = instantiate_parameters (loop, analyze_scalar_evolution (loop, var)); |
| if (TREE_CODE (chrec) != POLYNOMIAL_CHREC) |
| return; |
| |
| init = initial_condition_in_loop_num (chrec, loop->num); |
| step = evolution_part_in_loop_num (chrec, loop->num); |
| |
| /* If STEP is symbolic, we can't know whether INIT will be the |
| minimum or maximum value in the range. Also, unless INIT is |
| a simple expression, compare_values and possibly other functions |
| in tree-vrp won't be able to handle it. */ |
| if (step == NULL_TREE |
| || !is_gimple_min_invariant (step) |
| || !valid_value_p (init)) |
| return; |
| |
| dir = scev_direction (chrec); |
| if (/* Do not adjust ranges if we do not know whether the iv increases |
| or decreases, ... */ |
| dir == EV_DIR_UNKNOWN |
| /* ... or if it may wrap. */ |
| || scev_probably_wraps_p (init, step, stmt, |
| current_loops->parray[CHREC_VARIABLE (chrec)], |
| true)) |
| return; |
| |
| /* We use TYPE_MIN_VALUE and TYPE_MAX_VALUE here instead of |
| negative_overflow_infinity and positive_overflow_infinity, |
| because we have concluded that the loop probably does not |
| wrap. */ |
| |
| type = TREE_TYPE (var); |
| if (POINTER_TYPE_P (type) || !TYPE_MIN_VALUE (type)) |
| tmin = lower_bound_in_type (type, type); |
| else |
| tmin = TYPE_MIN_VALUE (type); |
| if (POINTER_TYPE_P (type) || !TYPE_MAX_VALUE (type)) |
| tmax = upper_bound_in_type (type, type); |
| else |
| tmax = TYPE_MAX_VALUE (type); |
| |
| if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED) |
| { |
| min = tmin; |
| max = tmax; |
| |
| /* For VARYING or UNDEFINED ranges, just about anything we get |
| from scalar evolutions should be better. */ |
| |
| if (dir == EV_DIR_DECREASES) |
| max = init; |
| else |
| min = init; |
| |
| /* If we would create an invalid range, then just assume we |
| know absolutely nothing. This may be over-conservative, |
| but it's clearly safe, and should happen only in unreachable |
| parts of code, or for invalid programs. */ |
| if (compare_values (min, max) == 1) |
| return; |
| |
| set_value_range (vr, VR_RANGE, min, max, vr->equiv); |
| } |
| else if (vr->type == VR_RANGE) |
| { |
| min = vr->min; |
| max = vr->max; |
| |
| if (dir == EV_DIR_DECREASES) |
| { |
| /* INIT is the maximum value. If INIT is lower than VR->MAX |
| but no smaller than VR->MIN, set VR->MAX to INIT. */ |
| if (compare_values (init, max) == -1) |
| { |
| max = init; |
| |
| /* If we just created an invalid range with the minimum |
| greater than the maximum, we fail conservatively. |
| This should happen only in unreachable |
| parts of code, or for invalid programs. */ |
| if (compare_values (min, max) == 1) |
| return; |
| } |
| |
| /* According to the loop information, the variable does not |
| overflow. If we think it does, probably because of an |
| overflow due to arithmetic on a different INF value, |
| reset now. */ |
| if (is_negative_overflow_infinity (min)) |
| min = tmin; |
| } |
| else |
| { |
| /* If INIT is bigger than VR->MIN, set VR->MIN to INIT. */ |
| if (compare_values (init, min) == 1) |
| { |
| min = init; |
| |
| /* Again, avoid creating invalid range by failing. */ |
| if (compare_values (min, max) == 1) |
| return; |
| } |
| |
| if (is_positive_overflow_infinity (max)) |
| max = tmax; |
| } |
| |
| set_value_range (vr, VR_RANGE, min, max, vr->equiv); |
| } |
| } |
| |
| /* Return true if VAR may overflow at STMT. This checks any available |
| loop information to see if we can determine that VAR does not |
| overflow. */ |
| |
| static bool |
| vrp_var_may_overflow (tree var, tree stmt) |
| { |
| struct loop *l; |
| tree chrec, init, step; |
| |
| if (current_loops == NULL) |
| return true; |
| |
| l = loop_containing_stmt (stmt); |
| if (l == NULL) |
| return true; |
| |
| chrec = instantiate_parameters (l, analyze_scalar_evolution (l, var)); |
| if (TREE_CODE (chrec) != POLYNOMIAL_CHREC) |
| return true; |
| |
| init = initial_condition_in_loop_num (chrec, l->num); |
| step = evolution_part_in_loop_num (chrec, l->num); |
| |
| if (step == NULL_TREE |
| || !is_gimple_min_invariant (step) |
| || !valid_value_p (init)) |
| return true; |
| |
| /* If we get here, we know something useful about VAR based on the |
| loop information. If it wraps, it may overflow. */ |
| |
| if (scev_probably_wraps_p (init, step, stmt, |
| current_loops->parray[CHREC_VARIABLE (chrec)], |
| true)) |
| return true; |
| |
| if (dump_file && (dump_flags & TDF_DETAILS) != 0) |
| { |
| print_generic_expr (dump_file, var, 0); |
| fprintf (dump_file, ": loop information indicates does not overflow\n"); |
| } |
| |
| return false; |
| } |
| |
| |
| /* Given two numeric value ranges VR0, VR1 and a comparison code COMP: |
| |
| - Return BOOLEAN_TRUE_NODE if VR0 COMP VR1 always returns true for |
| all the values in the ranges. |
| |
| - Return BOOLEAN_FALSE_NODE if the comparison always returns false. |
| |
| - Return NULL_TREE if it is not always possible to determine the |
| value of the comparison. |
| |
| Also set *STRICT_OVERFLOW_P to indicate whether a range with an |
| overflow infinity was used in the test. */ |
| |
| |
| static tree |
| compare_ranges (enum tree_code comp, value_range_t *vr0, value_range_t *vr1, |
| bool *strict_overflow_p) |
| { |
| /* VARYING or UNDEFINED ranges cannot be compared. */ |
| if (vr0->type == VR_VARYING |
| || vr0->type == VR_UNDEFINED |
| || vr1->type == VR_VARYING |
| || vr1->type == VR_UNDEFINED) |
| return NULL_TREE; |
| |
| /* Anti-ranges need to be handled separately. */ |
| if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE) |
| { |
| /* If both are anti-ranges, then we cannot compute any |
| comparison. */ |
| if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE) |
| return NULL_TREE; |
| |
| /* These comparisons are never statically computable. */ |
| if (comp == GT_EXPR |
| || comp == GE_EXPR |
| || comp == LT_EXPR |
| || comp == LE_EXPR) |
| return NULL_TREE; |
| |
| /* Equality can be computed only between a range and an |
| anti-range. ~[VAL1, VAL2] == [VAL1, VAL2] is always false. */ |
| if (vr0->type == VR_RANGE) |
| { |
| /* To simplify processing, make VR0 the anti-range. */ |
| value_range_t *tmp = vr0; |
| vr0 = vr1; |
| vr1 = tmp; |
| } |
| |
| gcc_assert (comp == NE_EXPR || comp == EQ_EXPR); |
| |
| if (compare_values_warnv (vr0->min, vr1->min, strict_overflow_p) == 0 |
| && compare_values_warnv (vr0->max, vr1->max, strict_overflow_p) == 0) |
| return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node; |
| |
| return NULL_TREE; |
| } |
| |
| if (!usable_range_p (vr0, strict_overflow_p) |
| || !usable_range_p (vr1, strict_overflow_p)) |
| return NULL_TREE; |
| |
| /* Simplify processing. If COMP is GT_EXPR or GE_EXPR, switch the |
| operands around and change the comparison code. */ |
| if (comp == GT_EXPR || comp == GE_EXPR) |
| { |
| value_range_t *tmp; |
| comp = (comp == GT_EXPR) ? LT_EXPR : LE_EXPR; |
| tmp = vr0; |
| vr0 = vr1; |
| vr1 = tmp; |
| } |
| |
| if (comp == EQ_EXPR) |
| { |
| /* Equality may only be computed if both ranges represent |
| exactly one value. */ |
| if (compare_values_warnv (vr0->min, vr0->max, strict_overflow_p) == 0 |
| && compare_values_warnv (vr1->min, vr1->max, strict_overflow_p) == 0) |
| { |
| int cmp_min = compare_values_warnv (vr0->min, vr1->min, |
| strict_overflow_p); |
| int cmp_max = compare_values_warnv (vr0->max, vr1->max, |
| strict_overflow_p); |
| if (cmp_min == 0 && cmp_max == 0) |
| return boolean_true_node; |
| else if (cmp_min != -2 && cmp_max != -2) |
| return boolean_false_node; |
| } |
| /* If [V0_MIN, V1_MAX] < [V1_MIN, V1_MAX] then V0 != V1. */ |
| else if (compare_values_warnv (vr0->min, vr1->max, |
| strict_overflow_p) == 1 |
| || compare_values_warnv (vr1->min, vr0->max, |
| strict_overflow_p) == 1) |
| return boolean_false_node; |
| |
| return NULL_TREE; |
| } |
| else if (comp == NE_EXPR) |
| { |
| int cmp1, cmp2; |
| |
| /* If VR0 is completely to the left or completely to the right |
| of VR1, they are always different. Notice that we need to |
| make sure that both comparisons yield similar results to |
| avoid comparing values that cannot be compared at |
| compile-time. */ |
| cmp1 = compare_values_warnv (vr0->max, vr1->min, strict_overflow_p); |
| cmp2 = compare_values_warnv (vr0->min, vr1->max, strict_overflow_p); |
| if ((cmp1 == -1 && cmp2 == -1) || (cmp1 == 1 && cmp2 == 1)) |
| return boolean_true_node; |
| |
| /* If VR0 and VR1 represent a single value and are identical, |
| return false. */ |
| else if (compare_values_warnv (vr0->min, vr0->max, |
| strict_overflow_p) == 0 |
| && compare_values_warnv (vr1->min, vr1->max, |
| strict_overflow_p) == 0 |
| && compare_values_warnv (vr0->min, vr1->min, |
| strict_overflow_p) == 0 |
| && compare_values_warnv (vr0->max, vr1->max, |
| strict_overflow_p) == 0) |
| return boolean_false_node; |
| |
| /* Otherwise, they may or may not be different. */ |
| else |
| return NULL_TREE; |
| } |
| else if (comp == LT_EXPR || comp == LE_EXPR) |
| { |
| int tst; |
| |
| /* If VR0 is to the left of VR1, return true. */ |
| tst = compare_values_warnv (vr0->max, vr1->min, strict_overflow_p); |
| if ((comp == LT_EXPR && tst == -1) |
| || (comp == LE_EXPR && (tst == -1 || tst == 0))) |
| { |
| if (overflow_infinity_range_p (vr0) |
| || overflow_infinity_range_p (vr1)) |
| *strict_overflow_p = true; |
| return boolean_true_node; |
| } |
| |
| /* If VR0 is to the right of VR1, return false. */ |
| tst = compare_values_warnv (vr0->min, vr1->max, strict_overflow_p); |
| if ((comp == LT_EXPR && (tst == 0 || tst == 1)) |
| || (comp == LE_EXPR && tst == 1)) |
| { |
| if (overflow_infinity_range_p (vr0) |
| || overflow_infinity_range_p (vr1)) |
| *strict_overflow_p = true; |
| return boolean_false_node; |
| } |
| |
| /* Otherwise, we don't know. */ |
| return NULL_TREE; |
| } |
| |
| gcc_unreachable (); |
| } |
| |
| |
| /* Given a value range VR, a value VAL and a comparison code COMP, return |
| BOOLEAN_TRUE_NODE if VR COMP VAL always returns true for all the |
| values in VR. Return BOOLEAN_FALSE_NODE if the comparison |
| always returns false. Return NULL_TREE if it is not always |
| possible to determine the value of the comparison. Also set |
| *STRICT_OVERFLOW_P to indicate whether a range with an overflow |
| infinity was used in the test. */ |
| |
| static tree |
| compare_range_with_value (enum tree_code comp, value_range_t *vr, tree val, |
| bool *strict_overflow_p) |
| { |
| if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED) |
| return NULL_TREE; |
| |
| /* Anti-ranges need to be handled separately. */ |
| if (vr->type == VR_ANTI_RANGE) |
| { |
| /* For anti-ranges, the only predicates that we can compute at |
| compile time are equality and inequality. */ |
| if (comp == GT_EXPR |
| || comp == GE_EXPR |
| || comp == LT_EXPR |
| || comp == LE_EXPR) |
| return NULL_TREE; |
| |
| /* ~[VAL_1, VAL_2] OP VAL is known if VAL_1 <= VAL <= VAL_2. */ |
| if (value_inside_range (val, vr) == 1) |
| return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node; |
| |
| return NULL_TREE; |
| } |
| |
| if (!usable_range_p (vr, strict_overflow_p)) |
| return NULL_TREE; |
| |
| if (comp == EQ_EXPR) |
| { |
| /* EQ_EXPR may only be computed if VR represents exactly |
| one value. */ |
| if (compare_values_warnv (vr->min, vr->max, strict_overflow_p) == 0) |
| { |
| int cmp = compare_values_warnv (vr->min, val, strict_overflow_p); |
| if (cmp == 0) |
| return boolean_true_node; |
| else if (cmp == -1 || cmp == 1 || cmp == 2) |
| return boolean_false_node; |
| } |
| else if (compare_values_warnv (val, vr->min, strict_overflow_p) == -1 |
| || compare_values_warnv (vr->max, val, strict_overflow_p) == -1) |
| return boolean_false_node; |
| |
| return NULL_TREE; |
| } |
| else if (comp == NE_EXPR) |
| { |
| /* If VAL is not inside VR, then they are always different. */ |
| if (compare_values_warnv (vr->max, val, strict_overflow_p) == -1 |
| || compare_values_warnv (vr->min, val, strict_overflow_p) == 1) |
| return boolean_true_node; |
| |
| /* If VR represents exactly one value equal to VAL, then return |
| false. */ |
| if (compare_values_warnv (vr->min, vr->max, strict_overflow_p) == 0 |
| && compare_values_warnv (vr->min, val, strict_overflow_p) == 0) |
| return boolean_false_node; |
| |
| /* Otherwise, they may or may not be different. */ |
| return NULL_TREE; |
| } |
| else if (comp == LT_EXPR || comp == LE_EXPR) |
| { |
| int tst; |
| |
| /* If VR is to the left of VAL, return true. */ |
| tst = compare_values_warnv (vr->max, val, strict_overflow_p); |
| if ((comp == LT_EXPR && tst == -1) |
| || (comp == LE_EXPR && (tst == -1 || tst == 0))) |
| { |
| if (overflow_infinity_range_p (vr)) |
| *strict_overflow_p = true; |
| return boolean_true_node; |
| } |
| |
| /* If VR is to the right of VAL, return false. */ |
| tst = compare_values_warnv (vr->min, val, strict_overflow_p); |
| if ((comp == LT_EXPR && (tst == 0 || tst == 1)) |
| || (comp == LE_EXPR && tst == 1)) |
| { |
| if (overflow_infinity_range_p (vr)) |
| *strict_overflow_p = true; |
| return boolean_false_node; |
| } |
| |
| /* Otherwise, we don't know. */ |
| return NULL_TREE; |
| } |
| else if (comp == GT_EXPR || comp == GE_EXPR) |
| { |
| int tst; |
| |
| /* If VR is to the right of VAL, return true. */ |
| tst = compare_values_warnv (vr->min, val, strict_overflow_p); |
| if ((comp == GT_EXPR && tst == 1) |
| || (comp == GE_EXPR && (tst == 0 || tst == 1))) |
| { |
| if (overflow_infinity_range_p (vr)) |
| *strict_overflow_p = true; |
| return boolean_true_node; |
| } |
| |
| /* If VR is to the left of VAL, return false. */ |
| tst = compare_values_warnv (vr->max, val, strict_overflow_p); |
| if ((comp == GT_EXPR && (tst == -1 || tst == 0)) |
| || (comp == GE_EXPR && tst == -1)) |
| { |
| if (overflow_infinity_range_p (vr)) |
| *strict_overflow_p = true; |
| return boolean_false_node; |
| } |
| |
| /* Otherwise, we don't know. */ |
| return NULL_TREE; |
| } |
| |
| gcc_unreachable (); |
| } |
| |
| |
| /* Debugging dumps. */ |
| |
| void dump_value_range (FILE *, value_range_t *); |
| void debug_value_range (value_range_t *); |
| void dump_all_value_ranges (FILE *); |
| void debug_all_value_ranges (void); |
| void dump_vr_equiv (FILE *, bitmap); |
| void debug_vr_equiv (bitmap); |
| |
| |
| /* Dump value range VR to FILE. */ |
| |
| void |
| dump_value_range (FILE *file, value_range_t *vr) |
| { |
| if (vr == NULL) |
| fprintf (file, "[]"); |
| else if (vr->type == VR_UNDEFINED) |
| fprintf (file, "UNDEFINED"); |
| else if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE) |
| { |
| tree type = TREE_TYPE (vr->min); |
| |
| fprintf (file, "%s[", (vr->type == VR_ANTI_RANGE) ? "~" : ""); |
| |
| if (is_negative_overflow_infinity (vr->min)) |
| fprintf (file, "-INF(OVF)"); |
| else if (INTEGRAL_TYPE_P (type) |
| && !TYPE_UNSIGNED (type) |
| && vrp_val_is_min (vr->min)) |
| fprintf (file, "-INF"); |
| else |
| print_generic_expr (file, vr->min, 0); |
| |
| fprintf (file, ", "); |
| |
| if (is_positive_overflow_infinity (vr->max)) |
| fprintf (file, "+INF(OVF)"); |
| else if (INTEGRAL_TYPE_P (type) |
| && vrp_val_is_max (vr->max)) |
| fprintf (file, "+INF"); |
| else |
| print_generic_expr (file, vr->max, 0); |
| |
| fprintf (file, "]"); |
| |
| if (vr->equiv) |
| { |
| bitmap_iterator bi; |
| unsigned i, c = 0; |
| |
| fprintf (file, " EQUIVALENCES: { "); |
| |
| EXECUTE_IF_SET_IN_BITMAP (vr->equiv, 0, i, bi) |
| { |
| print_generic_expr (file, ssa_name (i), 0); |
| fprintf (file, " "); |
| c++; |
| } |
| |
| fprintf (file, "} (%u elements)", c); |
| } |
| } |
| else if (vr->type == VR_VARYING) |
| fprintf (file, "VARYING"); |
| else |
| fprintf (file, "INVALID RANGE"); |
| } |
| |
| |
| /* Dump value range VR to stderr. */ |
| |
| void |
| debug_value_range (value_range_t *vr) |
| { |
| dump_value_range (stderr, vr); |
| fprintf (stderr, "\n"); |
| } |
| |
| |
| /* Dump value ranges of all SSA_NAMEs to FILE. */ |
| |
| void |
| dump_all_value_ranges (FILE *file) |
| { |
| size_t i; |
| |
| for (i = 0; i < num_ssa_names; i++) |
| { |
| if (vr_value[i]) |
| { |
| print_generic_expr (file, ssa_name (i), 0); |
| fprintf (file, ": "); |
| dump_value_range (file, vr_value[i]); |
| fprintf (file, "\n"); |
| } |
| } |
| |
| fprintf (file, "\n"); |
| } |
| |
| |
| /* Dump all value ranges to stderr. */ |
| |
| void |
| debug_all_value_ranges (void) |
| { |
| dump_all_value_ranges (stderr); |
| } |
| |
| |
| /* Given a COND_EXPR COND of the form 'V OP W', and an SSA name V, |
| create a new SSA name N and return the assertion assignment |
| 'V = ASSERT_EXPR <V, V OP W>'. */ |
| |
| static tree |
| build_assert_expr_for (tree cond, tree v) |
| { |
| tree n, assertion; |
| |
| gcc_assert (TREE_CODE (v) == SSA_NAME); |
| n = duplicate_ssa_name (v, NULL_TREE); |
| |
| if (COMPARISON_CLASS_P (cond)) |
| { |
| tree a = build2 (ASSERT_EXPR, TREE_TYPE (v), v, cond); |
| assertion = build2 (MODIFY_EXPR, TREE_TYPE (v), n, a); |
| } |
| else if (TREE_CODE (cond) == TRUTH_NOT_EXPR) |
| { |
| /* Given !V, build the assignment N = false. */ |
| tree op0 = TREE_OPERAND (cond, 0); |
| gcc_assert (op0 == v); |
| assertion = build2 (MODIFY_EXPR, TREE_TYPE (v), n, boolean_false_node); |
| } |
| else if (TREE_CODE (cond) == SSA_NAME) |
| { |
| /* Given V, build the assignment N = true. */ |
| gcc_assert (v == cond); |
| assertion = build2 (MODIFY_EXPR, TREE_TYPE (v), n, boolean_true_node); |
| } |
| else |
| gcc_unreachable (); |
| |
| SSA_NAME_DEF_STMT (n) = assertion; |
| |
| /* The new ASSERT_EXPR, creates a new SSA name that replaces the |
| operand of the ASSERT_EXPR. Register the new name and the old one |
| in the replacement table so that we can fix the SSA web after |
| adding all the ASSERT_EXPRs. */ |
| register_new_name_mapping (n, v); |
| |
| return assertion; |
| } |
| |
| |
| /* Return false if EXPR is a predicate expression involving floating |
| point values. */ |
| |
| static inline bool |
| fp_predicate (tree expr) |
| { |
| return (COMPARISON_CLASS_P (expr) |
| && FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0)))); |
| } |
| |
| |
| /* If the range of values taken by OP can be inferred after STMT executes, |
| return the comparison code (COMP_CODE_P) and value (VAL_P) that |
| describes the inferred range. Return true if a range could be |
| inferred. */ |
| |
| static bool |
| infer_value_range (tree stmt, tree op, enum tree_code *comp_code_p, tree *val_p) |
| { |
| *val_p = NULL_TREE; |
| *comp_code_p = ERROR_MARK; |
| |
| /* Do not attempt to infer anything in names that flow through |
| abnormal edges. */ |
| if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op)) |
| return false; |
| |
| /* Similarly, don't infer anything from statements that may throw |
| exceptions. */ |
| if (tree_could_throw_p (stmt)) |
| return false; |
| |
| /* If STMT is the last statement of a basic block with no |
| successors, there is no point inferring anything about any of its |
| operands. We would not be able to find a proper insertion point |
| for the assertion, anyway. */ |
| if (stmt_ends_bb_p (stmt) && EDGE_COUNT (bb_for_stmt (stmt)->succs) == 0) |
| return false; |
| |
| /* We can only assume that a pointer dereference will yield |
| non-NULL if -fdelete-null-pointer-checks is enabled. */ |
| if (flag_delete_null_pointer_checks && POINTER_TYPE_P (TREE_TYPE (op))) |
| { |
| bool is_store; |
| unsigned num_uses, num_derefs; |
| |
| count_uses_and_derefs (op, stmt, &num_uses, &num_derefs, &is_store); |
| if (num_derefs > 0) |
| { |
| *val_p = build_int_cst (TREE_TYPE (op), 0); |
| *comp_code_p = NE_EXPR; |
| return true; |
| } |
| } |
| |
| return false; |
| } |
| |
| |
| void dump_asserts_for (FILE *, tree); |
| void debug_asserts_for (tree); |
| void dump_all_asserts (FILE *); |
| void debug_all_asserts (void); |
| |
| /* Dump all the registered assertions for NAME to FILE. */ |
| |
| void |
| dump_asserts_for (FILE *file, tree name) |
| { |
| assert_locus_t loc; |
| |
| fprintf (file, "Assertions to be inserted for "); |
| print_generic_expr (file, name, 0); |
| fprintf (file, "\n"); |
| |
| loc = asserts_for[SSA_NAME_VERSION (name)]; |
| while (loc) |
| { |
| fprintf (file, "\t"); |
| print_generic_expr (file, bsi_stmt (loc->si), 0); |
| fprintf (file, "\n\tBB #%d", loc->bb->index); |
| if (loc->e) |
| { |
| fprintf (file, "\n\tEDGE %d->%d", loc->e->src->index, |
| loc->e->dest->index); |
| dump_edge_info (file, loc->e, 0); |
| } |
| fprintf (file, "\n\tPREDICATE: "); |
| print_generic_expr (file, name, 0); |
| fprintf (file, " %s ", tree_code_name[(int)loc->comp_code]); |
| print_generic_expr (file, loc->val, 0); |
| fprintf (file, "\n\n"); |
| loc = loc->next; |
| } |
| |
| fprintf (file, "\n"); |
| } |
| |
| |
| /* Dump all the registered assertions for NAME to stderr. */ |
| |
| void |
| debug_asserts_for (tree name) |
| { |
| dump_asserts_for (stderr, name); |
| } |
| |
| |
| /* Dump all the registered assertions for all the names to FILE. */ |
| |
| void |
| dump_all_asserts (FILE *file) |
| { |
| unsigned i; |
| bitmap_iterator bi; |
| |
| fprintf (file, "\nASSERT_EXPRs to be inserted\n\n"); |
| EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi) |
| dump_asserts_for (file, ssa_name (i)); |
| fprintf (file, "\n"); |
| } |
| |
| |
| /* Dump all the registered assertions for all the names to stderr. */ |
| |
| void |
| debug_all_asserts (void) |
| { |
| dump_all_asserts (stderr); |
| } |
| |
| |
| /* If NAME doesn't have an ASSERT_EXPR registered for asserting |
| 'NAME COMP_CODE VAL' at a location that dominates block BB or |
| E->DEST, then register this location as a possible insertion point |
| for ASSERT_EXPR <NAME, NAME COMP_CODE VAL>. |
| |
| BB, E and SI provide the exact insertion point for the new |
| ASSERT_EXPR. If BB is NULL, then the ASSERT_EXPR is to be inserted |
| on edge E. Otherwise, if E is NULL, the ASSERT_EXPR is inserted on |
| BB. If SI points to a COND_EXPR or a SWITCH_EXPR statement, then E |
| must not be NULL. */ |
| |
| static void |
| register_new_assert_for (tree name, |
| enum tree_code comp_code, |
| tree val, |
| basic_block bb, |
| edge e, |
| block_stmt_iterator si) |
| { |
| assert_locus_t n, loc, last_loc; |
| bool found; |
| basic_block dest_bb; |
| |
| #if defined ENABLE_CHECKING |
| gcc_assert (bb == NULL || e == NULL); |
| |
| if (e == NULL) |
| gcc_assert (TREE_CODE (bsi_stmt (si)) != COND_EXPR |
| && TREE_CODE (bsi_stmt (si)) != SWITCH_EXPR); |
| #endif |
| |
| /* The new assertion A will be inserted at BB or E. We need to |
| determine if the new location is dominated by a previously |
| registered location for A. If we are doing an edge insertion, |
| assume that A will be inserted at E->DEST. Note that this is not |
| necessarily true. |
| |
| If E is a critical edge, it will be split. But even if E is |
| split, the new block will dominate the same set of blocks that |
| E->DEST dominates. |
| |
| The reverse, however, is not true, blocks dominated by E->DEST |
| will not be dominated by the new block created to split E. So, |
| if the insertion location is on a critical edge, we will not use |
| the new location to move another assertion previously registered |
| at a block dominated by E->DEST. */ |
| dest_bb = (bb) ? bb : e->dest; |
| |
| /* If NAME already has an ASSERT_EXPR registered for COMP_CODE and |
| VAL at a block dominating DEST_BB, then we don't need to insert a new |
| one. Similarly, if the same assertion already exists at a block |
| dominated by DEST_BB and the new location is not on a critical |
| edge, then update the existing location for the assertion (i.e., |
| move the assertion up in the dominance tree). |
| |
| Note, this is implemented as a simple linked list because there |
| should not be more than a handful of assertions registered per |
| name. If this becomes a performance problem, a table hashed by |
| COMP_CODE and VAL could be implemented. */ |
| loc = asserts_for[SSA_NAME_VERSION (name)]; |
| last_loc = loc; |
| found = false; |
| while (loc) |
| { |
| if (loc->comp_code == comp_code |
| && (loc->val == val |
| || operand_equal_p (loc->val, val, 0))) |
| { |
| /* If the assertion NAME COMP_CODE VAL has already been |
| registered at a basic block that dominates DEST_BB, then |
| we don't need to insert the same assertion again. Note |
| that we don't check strict dominance here to avoid |
| replicating the same assertion inside the same basic |
| block more than once (e.g., when a pointer is |
| dereferenced several times inside a block). |
| |
| An exception to this rule are edge insertions. If the |
| new assertion is to be inserted on edge E, then it will |
| dominate all the other insertions that we may want to |
| insert in DEST_BB. So, if we are doing an edge |
| insertion, don't do this dominance check. */ |
| if (e == NULL |
| && dominated_by_p (CDI_DOMINATORS, dest_bb, loc->bb)) |
| return; |
| |
| /* Otherwise, if E is not a critical edge and DEST_BB |
| dominates the existing location for the assertion, move |
| the assertion up in the dominance tree by updating its |
| location information. */ |
| if ((e == NULL || !EDGE_CRITICAL_P (e)) |
| && dominated_by_p (CDI_DOMINATORS, loc->bb, dest_bb)) |
| { |
| loc->bb = dest_bb; |
| loc->e = e; |
| loc->si = si; |
| return; |
| } |
| } |
| |
| /* Update the last node of the list and move to the next one. */ |
| last_loc = loc; |
| loc = loc->next; |
| } |
| |
| /* If we didn't find an assertion already registered for |
| NAME COMP_CODE VAL, add a new one at the end of the list of |
| assertions associated with NAME. */ |
| n = XNEW (struct assert_locus_d); |
| n->bb = dest_bb; |
| n->e = e; |
| n->si = si; |
| n->comp_code = comp_code; |
| n->val = val; |
| n->next = NULL; |
| |
| if (last_loc) |
| last_loc->next = n; |
| else |
| asserts_for[SSA_NAME_VERSION (name)] = n; |
| |
| bitmap_set_bit (need_assert_for, SSA_NAME_VERSION (name)); |
| } |
| |
| |
| /* Try to register an edge assertion for SSA name NAME on edge E for |
| the conditional jump pointed to by SI. Return true if an assertion |
| for NAME could be registered. */ |
| |
| static bool |
| register_edge_assert_for (tree name, edge e, block_stmt_iterator si) |
| { |
| tree val, stmt; |
| enum tree_code comp_code; |
| |
| stmt = bsi_stmt (si); |
| |
| /* Do not attempt to infer anything in names that flow through |
| abnormal edges. */ |
| if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name)) |
| return false; |
| |
| /* If NAME was not found in the sub-graph reachable from E, then |
| there's nothing to do. */ |
| if (!TEST_BIT (found_in_subgraph, SSA_NAME_VERSION (name))) |
| return false; |
| |
| /* We found a use of NAME in the sub-graph rooted at E->DEST. |
| Register an assertion for NAME according to the value that NAME |
| takes on edge E. */ |
| if (TREE_CODE (stmt) == COND_EXPR) |
| { |
| /* If BB ends in a COND_EXPR then NAME then we should insert |
| the original predicate on EDGE_TRUE_VALUE and the |
| opposite predicate on EDGE_FALSE_VALUE. */ |
| tree cond = COND_EXPR_COND (stmt); |
| bool is_else_edge = (e->flags & EDGE_FALSE_VALUE) != 0; |
| |
| /* Predicates may be a single SSA name or NAME OP VAL. */ |
| if (cond == name) |
| { |
| /* If the predicate is a name, it must be NAME, in which |
| case we create the predicate NAME == true or |
| NAME == false accordingly. */ |
| comp_code = EQ_EXPR; |
| val = (is_else_edge) ? boolean_false_node : boolean_true_node; |
| } |
| else |
| { |
| /* Otherwise, we have a comparison of the form NAME COMP VAL |
| or VAL COMP NAME. */ |
| if (name == TREE_OPERAND (cond, 1)) |
| { |
| /* If the predicate is of the form VAL COMP NAME, flip |
| COMP around because we need to register NAME as the |
| first operand in the predicate. */ |
| comp_code = swap_tree_comparison (TREE_CODE (cond)); |
| val = TREE_OPERAND (cond, 0); |
| } |
| else |
| { |
| /* The comparison is of the form NAME COMP VAL, so the |
| comparison code remains unchanged. */ |
| comp_code = TREE_CODE (cond); |
| val = TREE_OPERAND (cond, 1); |
| } |
| |
| /* If we are inserting the assertion on the ELSE edge, we |
| need to invert the sign comparison. */ |
| if (is_else_edge) |
| comp_code = invert_tree_comparison (comp_code, 0); |
| |
| /* Do not register always-false predicates. FIXME, this |
| works around a limitation in fold() when dealing with |
| enumerations. Given 'enum { N1, N2 } x;', fold will not |
| fold 'if (x > N2)' to 'if (0)'. */ |
| if ((comp_code == GT_EXPR || comp_code == LT_EXPR) |
| && (INTEGRAL_TYPE_P (TREE_TYPE (val)) |
| || SCALAR_FLOAT_TYPE_P (TREE_TYPE (val)))) |
| { |
| tree min = TYPE_MIN_VALUE (TREE_TYPE (val)); |
| tree max = TYPE_MAX_VALUE (TREE_TYPE (val)); |
| |
| if (comp_code == GT_EXPR && compare_values (val, max) == 0) |
| return false; |
| |
| if (comp_code == LT_EXPR && compare_values (val, min) == 0) |
| return false; |
| } |
| } |
| } |
| else |
| { |
| /* FIXME. Handle SWITCH_EXPR. */ |
| gcc_unreachable (); |
| } |
| |
| register_new_assert_for (name, comp_code, val, NULL, e, si); |
| return true; |
| } |
| |
| |
| static bool find_assert_locations (basic_block bb); |
| |
| /* Determine whether the outgoing edges of BB should receive an |
| ASSERT_EXPR for each of the operands of BB's last statement. The |
| last statement of BB must be a COND_EXPR or a SWITCH_EXPR. |
| |
| If any of the sub-graphs rooted at BB have an interesting use of |
| the predicate operands, an assert location node is added to the |
| list of assertions for the corresponding operands. */ |
| |
| static bool |
| find_conditional_asserts (basic_block bb) |
| { |
| bool need_assert; |
| block_stmt_iterator last_si; |
| tree op, last; |
| edge_iterator ei; |
| edge e; |
| ssa_op_iter iter; |
| |
| need_assert = false; |
| last_si = bsi_last (bb); |
| last = bsi_stmt (last_si); |
| |
| /* Look for uses of the operands in each of the sub-graphs |
| rooted at BB. We need to check each of the outgoing edges |
| separately, so that we know what kind of ASSERT_EXPR to |
| insert. */ |
| FOR_EACH_EDGE (e, ei, bb->succs) |
| { |
| if (e->dest == bb) |
| continue; |
| |
| /* Remove the COND_EXPR operands from the FOUND_IN_SUBGRAPH bitmap. |
| Otherwise, when we finish traversing each of the sub-graphs, we |
| won't know whether the variables were found in the sub-graphs or |
| if they had been found in a block upstream from BB. |
| |
| This is actually a bad idea is some cases, particularly jump |
| threading. Consider a CFG like the following: |
| |
| 0 |
| /| |
| 1 | |
| \| |
| 2 |
| / \ |
| 3 4 |
| |
| Assume that one or more operands in the conditional at the |
| end of block 0 are used in a conditional in block 2, but not |
| anywhere in block 1. In this case we will not insert any |
| assert statements in block 1, which may cause us to miss |
| opportunities to optimize, particularly for jump threading. */ |
| FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE) |
| RESET_BIT (found_in_subgraph, SSA_NAME_VERSION (op)); |
| |
| /* Traverse the strictly dominated sub-graph rooted at E->DEST |
| to determine if any of the operands in the conditional |
| predicate are used. */ |
| if (e->dest != bb) |
| need_assert |= find_assert_locations (e->dest); |
| |
| /* Register the necessary assertions for each operand in the |
| conditional predicate. */ |
| FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE) |
| need_assert |= register_edge_assert_for (op, e, last_si); |
| } |
| |
| /* Finally, indicate that we have found the operands in the |
| conditional. */ |
| FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE) |
| SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op)); |
| |
| return need_assert; |
| } |
| |
| |
| /* Traverse all the statements in block BB looking for statements that |
| may generate useful assertions for the SSA names in their operand. |
| If a statement produces a useful assertion A for name N_i, then the |
| list of assertions already generated for N_i is scanned to |
| determine if A is actually needed. |
| |
| If N_i already had the assertion A at a location dominating the |
| current location, then nothing needs to be done. Otherwise, the |
| new location for A is recorded instead. |
| |
| 1- For every statement S in BB, all the variables used by S are |
| added to bitmap FOUND_IN_SUBGRAPH. |
| |
| 2- If statement S uses an operand N in a way that exposes a known |
| value range for N, then if N was not already generated by an |
| ASSERT_EXPR, create a new assert location for N. For instance, |
| if N is a pointer and the statement dereferences it, we can |
| assume that N is not NULL. |
| |
| 3- COND_EXPRs are a special case of #2. We can derive range |
| information from the predicate but need to insert different |
| ASSERT_EXPRs for each of the sub-graphs rooted at the |
| conditional block. If the last statement of BB is a conditional |
| expression of the form 'X op Y', then |
| |
| a) Remove X and Y from the set FOUND_IN_SUBGRAPH. |
| |
| b) If the conditional is the only entry point to the sub-graph |
| corresponding to the THEN_CLAUSE, recurse into it. On |
| return, if X and/or Y are marked in FOUND_IN_SUBGRAPH, then |
| an ASSERT_EXPR is added for the corresponding variable. |
| |
| c) Repeat step (b) on the ELSE_CLAUSE. |
| |
| d) Mark X and Y in FOUND_IN_SUBGRAPH. |
| |
| For instance, |
| |
| if (a == 9) |
| b = a; |
| else |
| b = c + 1; |
| |
| In this case, an assertion on the THEN clause is useful to |
| determine that 'a' is always 9 on that edge. However, an assertion |
| on the ELSE clause would be unnecessary. |
| |
| 4- If BB does not end in a conditional expression, then we recurse |
| into BB's dominator children. |
| |
| At the end of the recursive traversal, every SSA name will have a |
| list of locations where ASSERT_EXPRs should be added. When a new |
| location for name N is found, it is registered by calling |
| register_new_assert_for. That function keeps track of all the |
| registered assertions to prevent adding unnecessary assertions. |
| For instance, if a pointer P_4 is dereferenced more than once in a |
| dominator tree, only the location dominating all the dereference of |
| P_4 will receive an ASSERT_EXPR. |
| |
| If this function returns true, then it means that there are names |
| for which we need to generate ASSERT_EXPRs. Those assertions are |
| inserted by process_assert_insertions. |
| |
| TODO. Handle SWITCH_EXPR. */ |
| |
| static bool |
| find_assert_locations (basic_block bb) |
| { |
| block_stmt_iterator si; |
| tree last, phi; |
| bool need_assert; |
| basic_block son; |
| |
| if (TEST_BIT (blocks_visited, bb->index)) |
| return false; |
| |
| SET_BIT (blocks_visited, bb->index); |
| |
| need_assert = false; |
| |
| /* Traverse all PHI nodes in BB marking used operands. */ |
| for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi)) |
| { |
| use_operand_p arg_p; |
| ssa_op_iter i; |
| |
| FOR_EACH_PHI_ARG (arg_p, phi, i, SSA_OP_USE) |
| { |
| tree arg = USE_FROM_PTR (arg_p); |
| if (TREE_CODE (arg) == SSA_NAME) |
| { |
| gcc_assert (is_gimple_reg (PHI_RESULT (phi))); |
| SET_BIT (found_in_subgraph, SSA_NAME_VERSION (arg)); |
| } |
| } |
| } |
| |
| /* Traverse all the statements in BB marking used names and looking |
| for statements that may infer assertions for their used operands. */ |
| last = NULL_TREE; |
| for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si)) |
| { |
| tree stmt, op; |
| ssa_op_iter i; |
| |
| stmt = bsi_stmt (si); |
| |
| /* See if we can derive an assertion for any of STMT's operands. */ |
| FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_USE) |
| { |
| tree value; |
| enum tree_code comp_code; |
| |
| /* Mark OP in bitmap FOUND_IN_SUBGRAPH. If STMT is inside |
| the sub-graph of a conditional block, when we return from |
| this recursive walk, our parent will use the |
| FOUND_IN_SUBGRAPH bitset to determine if one of the |
| operands it was looking for was present in the sub-graph. */ |
| SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op)); |
| |
| /* If OP is used in such a way that we can infer a value |
| range for it, and we don't find a previous assertion for |
| it, create a new assertion location node for OP. */ |
| if (infer_value_range (stmt, op, &comp_code, &value)) |
| { |
| /* If we are able to infer a nonzero value range for OP, |
| then walk backwards through the use-def chain to see if OP |
| was set via a typecast. |
| |
| If so, then we can also infer a nonzero value range |
| for the operand of the NOP_EXPR. */ |
| if (comp_code == NE_EXPR && integer_zerop (value)) |
| { |
| tree t = op; |
| tree def_stmt = SSA_NAME_DEF_STMT (t); |
| |
| while (TREE_CODE (def_stmt) == MODIFY_EXPR |
| && TREE_CODE (TREE_OPERAND (def_stmt, 1)) == NOP_EXPR |
| && TREE_CODE (TREE_OPERAND (TREE_OPERAND (def_stmt, 1), 0)) == SSA_NAME |
| && POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (TREE_OPERAND (def_stmt, 1), 0)))) |
| { |
| t = TREE_OPERAND (TREE_OPERAND (def_stmt, 1), 0); |
| def_stmt = SSA_NAME_DEF_STMT (t); |
| |
| /* Note we want to register the assert for the |
| operand of the NOP_EXPR after SI, not after the |
| conversion. */ |
| if (! has_single_use (t)) |
| { |
| register_new_assert_for (t, comp_code, value, |
| bb, NULL, si); |
| need_assert = true; |
| } |
| } |
| } |
| |
| /* If OP is used only once, namely in this STMT, don't |
| bother creating an ASSERT_EXPR for it. Such an |
| ASSERT_EXPR would do nothing but increase compile time. */ |
| if (!has_single_use (op)) |
| { |
| register_new_assert_for (op, comp_code, value, bb, NULL, si); |
| need_assert = true; |
| } |
| } |
| } |
| |
| /* Remember the last statement of the block. */ |
| last = stmt; |
| } |
| |
| /* If BB's last statement is a conditional expression |
| involving integer operands, recurse into each of the sub-graphs |
| rooted at BB to determine if we need to add ASSERT_EXPRs. */ |
| if (last |
| && TREE_CODE (last) == COND_EXPR |
| && !fp_predicate (COND_EXPR_COND (last)) |
| && !ZERO_SSA_OPERANDS (last, SSA_OP_USE)) |
| need_assert |= find_conditional_asserts (bb); |
| |
| /* Recurse into the dominator children of BB. */ |
| for (son = first_dom_son (CDI_DOMINATORS, bb); |
| son; |
| son = next_dom_son (CDI_DOMINATORS, son)) |
| need_assert |= find_assert_locations (son); |
| |
| return need_assert; |
| } |
| |
| |
| /* Create an ASSERT_EXPR for NAME and insert it in the location |
| indicated by LOC. Return true if we made any edge insertions. */ |
| |
| static bool |
| process_assert_insertions_for (tree name, assert_locus_t loc) |
| { |
| /* Build the comparison expression NAME_i COMP_CODE VAL. */ |
| tree stmt, cond, assert_expr; |
| edge_iterator ei; |
| edge e; |
| |
| cond = build2 (loc->comp_code, boolean_type_node, name, loc->val); |
| assert_expr = build_assert_expr_for (cond, name); |
| |
| if (loc->e) |
| { |
| /* We have been asked to insert the assertion on an edge. This |
| is used only by COND_EXPR and SWITCH_EXPR assertions. */ |
| #if defined ENABLE_CHECKING |
| gcc_assert (TREE_CODE (bsi_stmt (loc->si)) == COND_EXPR |
| || TREE_CODE (bsi_stmt (loc->si)) == SWITCH_EXPR); |
| #endif |
| |
| bsi_insert_on_edge (loc->e, assert_expr); |
| return true; |
| } |
| |
| /* Otherwise, we can insert right after LOC->SI iff the |
| statement must not be the last statement in the block. */ |
| stmt = bsi_stmt (loc->si); |
| if (!stmt_ends_bb_p (stmt)) |
| { |
| bsi_insert_after (&loc->si, assert_expr, BSI_SAME_STMT); |
| return false; |
| } |
| |
| /* If STMT must be the last statement in BB, we can only insert new |
| assertions on the non-abnormal edge out of BB. Note that since |
| STMT is not control flow, there may only be one non-abnormal edge |
| out of BB. */ |
| FOR_EACH_EDGE (e, ei, loc->bb->succs) |
| if (!(e->flags & EDGE_ABNORMAL)) |
| { |
| bsi_insert_on_edge (e, assert_expr); |
| return true; |
| } |
| |
| gcc_unreachable (); |
| } |
| |
| |
| /* Process all the insertions registered for every name N_i registered |
| in NEED_ASSERT_FOR. The list of assertions to be inserted are |
| found in ASSERTS_FOR[i]. */ |
| |
| static void |
| process_assert_insertions (void) |
| { |
| unsigned i; |
| bitmap_iterator bi; |
| bool update_edges_p = false; |
| int num_asserts = 0; |
| |
| if (dump_file && (dump_flags & TDF_DETAILS)) |
| dump_all_asserts (dump_file); |
| |
| EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi) |
| { |
| assert_locus_t loc = asserts_for[i]; |
| gcc_assert (loc); |
| |
| while (loc) |
| { |
| assert_locus_t next = loc->next; |
| update_edges_p |= process_assert_insertions_for (ssa_name (i), loc); |
| free (loc); |
| loc = next; |
| num_asserts++; |
| } |
| } |
| |
| if (update_edges_p) |
| bsi_commit_edge_inserts (); |
| |
| if (dump_file && (dump_flags & TDF_STATS)) |
| fprintf (dump_file, "\nNumber of ASSERT_EXPR expressions inserted: %d\n\n", |
| num_asserts); |
| } |
| |
| |
| /* Traverse the flowgraph looking for conditional jumps to insert range |
| expressions. These range expressions are meant to provide information |
| to optimizations that need to reason in terms of value ranges. They |
| will not be expanded into RTL. For instance, given: |
| |
| x = ... |
| y = ... |
| if (x < y) |
| y = x - 2; |
| else |
| x = y + 3; |
| |
| this pass will transform the code into: |
| |
| x = ... |
| y = ... |
| if (x < y) |
| { |
| x = ASSERT_EXPR <x, x < y> |
| y = x - 2 |
| } |
| else |
| { |
| y = ASSERT_EXPR <y, x <= y> |
| x = y + 3 |
| } |
| |
| The idea is that once copy and constant propagation have run, other |
| optimizations will be able to determine what ranges of values can 'x' |
| take in different paths of the code, simply by checking the reaching |
| definition of 'x'. */ |
| |
| static void |
| insert_range_assertions (void) |
| { |
| edge e; |
| edge_iterator ei; |
| bool update_ssa_p; |
| |
| found_in_subgraph = sbitmap_alloc (num_ssa_names); |
| sbitmap_zero (found_in_subgraph); |
| |
| blocks_visited = sbitmap_alloc (last_basic_block); |
| sbitmap_zero (blocks_visited); |
| |
| need_assert_for = BITMAP_ALLOC (NULL); |
| asserts_for = XNEWVEC (assert_locus_t, num_ssa_names); |
| memset (asserts_for, 0, num_ssa_names * sizeof (assert_locus_t)); |
| |
| calculate_dominance_info (CDI_DOMINATORS); |
| |
| update_ssa_p = false; |
| FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs) |
| if (find_assert_locations (e->dest)) |
| update_ssa_p = true; |
| |
| if (update_ssa_p) |
| { |
| process_assert_insertions (); |
| update_ssa (TODO_update_ssa_no_phi); |
| } |
| |
| if (dump_file && (dump_flags & TDF_DETAILS)) |
| { |
| fprintf (dump_file, "\nSSA form after inserting ASSERT_EXPRs\n"); |
| dump_function_to_file (current_function_decl, dump_file, dump_flags); |
| } |
| |
| sbitmap_free (found_in_subgraph); |
| free (asserts_for); |
| BITMAP_FREE (need_assert_for); |
| } |
| |
| |
| /* Convert range assertion expressions into the implied copies and |
| copy propagate away the copies. Doing the trivial copy propagation |
| here avoids the need to run the full copy propagation pass after |
| VRP. |
| |
| FIXME, this will eventually lead to copy propagation removing the |
| names that had useful range information attached to them. For |
| instance, if we had the assertion N_i = ASSERT_EXPR <N_j, N_j > 3>, |
| then N_i will have the range [3, +INF]. |
| |
| However, by converting the assertion into the implied copy |
| operation N_i = N_j, we will then copy-propagate N_j into the uses |
| of N_i and lose the range information. We may want to hold on to |
| ASSERT_EXPRs a little while longer as the ranges could be used in |
| things like jump threading. |
| |
| The problem with keeping ASSERT_EXPRs around is that passes after |
| VRP need to handle them appropriately. |
| |
| Another approach would be to make the range information a first |
| class property of the SSA_NAME so that it can be queried from |
| any pass. This is made somewhat more complex by the need for |
| multiple ranges to be associated with one SSA_NAME. */ |
| |
| static void |
| remove_range_assertions (void) |
| { |
| basic_block bb; |
| block_stmt_iterator si; |
| |
| /* Note that the BSI iterator bump happens at the bottom of the |
| loop and no bump is necessary if we're removing the statement |
| referenced by the current BSI. */ |
| FOR_EACH_BB (bb) |
| for (si = bsi_start (bb); !bsi_end_p (si);) |
| { |
| tree stmt = bsi_stmt (si); |
| tree use_stmt; |
| |
| if (TREE_CODE (stmt) == MODIFY_EXPR |
| && TREE_CODE (TREE_OPERAND (stmt, 1)) == ASSERT_EXPR) |
| { |
| tree rhs = TREE_OPERAND (stmt, 1), var; |
| tree cond = fold (ASSERT_EXPR_COND (rhs)); |
| use_operand_p use_p; |
| imm_use_iterator iter; |
| |
| gcc_assert (cond != boolean_false_node); |
| |
| /* Propagate the RHS into every use of the LHS. */ |
| var = ASSERT_EXPR_VAR (rhs); |
| FOR_EACH_IMM_USE_STMT (use_stmt, iter, TREE_OPERAND (stmt, 0)) |
| FOR_EACH_IMM_USE_ON_STMT (use_p, iter) |
| { |
| SET_USE (use_p, var); |
| gcc_assert (TREE_CODE (var) == SSA_NAME); |
| } |
| |
| /* And finally, remove the copy, it is not needed. */ |
| bsi_remove (&si, true); |
| } |
| else |
| bsi_next (&si); |
| } |
| |
| sbitmap_free (blocks_visited); |
| } |
| |
| |
| /* Return true if STMT is interesting for VRP. */ |
| |
| static bool |
| stmt_interesting_for_vrp (tree stmt) |
| { |
| if (TREE_CODE (stmt) == PHI_NODE |
| && is_gimple_reg (PHI_RESULT (stmt)) |
| && (INTEGRAL_TYPE_P (TREE_TYPE (PHI_RESULT (stmt))) |
| || POINTER_TYPE_P (TREE_TYPE (PHI_RESULT (stmt))))) |
| return true; |
| else if (TREE_CODE (stmt) == MODIFY_EXPR) |
| { |
| tree lhs = TREE_OPERAND (stmt, 0); |
| tree rhs = TREE_OPERAND (stmt, 1); |
| |
| /* In general, assignments with virtual operands are not useful |
| for deriving ranges, with the obvious exception of calls to |
| builtin functions. */ |
| if (TREE_CODE (lhs) == SSA_NAME |
| && (INTEGRAL_TYPE_P (TREE_TYPE (lhs)) |
| || POINTER_TYPE_P (TREE_TYPE (lhs))) |
| && ((TREE_CODE (rhs) == CALL_EXPR |
| && TREE_CODE (TREE_OPERAND (rhs, 0)) == ADDR_EXPR |
| && DECL_P (TREE_OPERAND (TREE_OPERAND (rhs, 0), 0)) |
| && DECL_IS_BUILTIN (TREE_OPERAND (TREE_OPERAND (rhs, 0), 0))) |
| || ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))) |
| return true; |
| } |
| else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR) |
| return true; |
| |
| return false; |
| } |
| |
| |
| /* Initialize local data structures for VRP. */ |
| |
| static void |
| vrp_initialize (void) |
| { |
| basic_block bb; |
| |
| vr_value = XNEWVEC (value_range_t *, num_ssa_names); |
| memset (vr_value, 0, num_ssa_names * sizeof (value_range_t *)); |
| |
| FOR_EACH_BB (bb) |
| { |
| block_stmt_iterator si; |
| tree phi; |
| |
| for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi)) |
| { |
| if (!stmt_interesting_for_vrp (phi)) |
| { |
| tree lhs = PHI_RESULT (phi); |
| set_value_range_to_varying (get_value_range (lhs)); |
| DONT_SIMULATE_AGAIN (phi) = true; |
| } |
| else |
| DONT_SIMULATE_AGAIN (phi) = false; |
| } |
| |
| for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si)) |
| { |
| tree stmt = bsi_stmt (si); |
| |
| if (!stmt_interesting_for_vrp (stmt)) |
| { |
| ssa_op_iter i; |
| tree def; |
| FOR_EACH_SSA_TREE_OPERAND (def, stmt, i, SSA_OP_DEF) |
| set_value_range_to_varying (get_value_range (def)); |
| DONT_SIMULATE_AGAIN (stmt) = true; |
| } |
| else |
| { |
| DONT_SIMULATE_AGAIN (stmt) = false; |
| } |
| } |
| } |
| } |
| |
| |
| /* Visit assignment STMT. If it produces an interesting range, record |
| the SSA name in *OUTPUT_P. */ |
| |
| static enum ssa_prop_result |
| vrp_visit_assignment (tree stmt, tree *output_p) |
| { |
| tree lhs, rhs, def; |
| ssa_op_iter iter; |
| |
| lhs = TREE_OPERAND (stmt, 0); |
| rhs = TREE_OPERAND (stmt, 1); |
| |
| /* We only keep track of ranges in integral and pointer types. */ |
| if (TREE_CODE (lhs) == SSA_NAME |
| && ((INTEGRAL_TYPE_P (TREE_TYPE (lhs)) |
| /* It is valid to have NULL MIN/MAX values on a type. See |
| build_range_type. */ |
| && TYPE_MIN_VALUE (TREE_TYPE (lhs)) |
| && TYPE_MAX_VALUE (TREE_TYPE (lhs))) |
| || POINTER_TYPE_P (TREE_TYPE (lhs)))) |
| { |
| struct loop *l; |
| value_range_t new_vr = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL }; |
| |
| extract_range_from_expr (&new_vr, rhs); |
| |
| /* If STMT is inside a loop, we may be able to know something |
| else about the range of LHS by examining scalar evolution |
| information. */ |
| if (current_loops && (l = loop_containing_stmt (stmt))) |
| adjust_range_with_scev (&new_vr, l, stmt, lhs); |
| |
| if (update_value_range (lhs, &new_vr)) |
| { |
| *output_p = lhs; |
| |
| if (dump_file && (dump_flags & TDF_DETAILS)) |
| { |
| fprintf (dump_file, "Found new range for "); |
| print_generic_expr (dump_file, lhs, 0); |
| fprintf (dump_file, ": "); |
| dump_value_range (dump_file, &new_vr); |
| fprintf (dump_file, "\n\n"); |
| } |
| |
| if (new_vr.type == VR_VARYING) |
| return SSA_PROP_VARYING; |
| |
| return SSA_PROP_INTERESTING; |
| } |
| |
| return SSA_PROP_NOT_INTERESTING; |
| } |
| |
| /* Every other statement produces no useful ranges. */ |
| FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF) |
| set_value_range_to_varying (get_value_range (def)); |
| |
| return SSA_PROP_VARYING; |
| } |
| |
| |
| /* Compare all the value ranges for names equivalent to VAR with VAL |
| using comparison code COMP. Return the same value returned by |
| compare_range_with_value, including the setting of |
| *STRICT_OVERFLOW_P. */ |
| |
| static tree |
| compare_name_with_value (enum tree_code comp, tree var, tree val, |
| bool *strict_overflow_p) |
| { |
| bitmap_iterator bi; |
| unsigned i; |
| bitmap e; |
| tree retval, t; |
| int used_strict_overflow; |
| |
| t = retval = NULL_TREE; |
| |
| /* Get the set of equivalences for VAR. */ |
| e = get_value_range (var)->equiv; |
| |
| /* Add VAR to its own set of equivalences so that VAR's value range |
| is processed by this loop (otherwise, we would have to replicate |
| the body of the loop just to check VAR's value range). */ |
| bitmap_set_bit (e, SSA_NAME_VERSION (var)); |
| |
| /* Start at -1. Set it to 0 if we do a comparison without relying |
| on overflow, or 1 if all comparisons rely on overflow. */ |
| used_strict_overflow = -1; |
| |
| EXECUTE_IF_SET_IN_BITMAP (e, 0, i, bi) |
| { |
| bool sop; |
| |
| value_range_t equiv_vr = *(vr_value[i]); |
| |
| /* If name N_i does not have a valid range, use N_i as its own |
| range. This allows us to compare against names that may |
| have N_i in their ranges. */ |
| if (equiv_vr.type == VR_VARYING || equiv_vr.type == VR_UNDEFINED) |
| { |
| equiv_vr.type = VR_RANGE; |
| equiv_vr.min = ssa_name (i); |
| equiv_vr.max = ssa_name (i); |
| } |
| |
| sop = false; |
| t = compare_range_with_value (comp, &equiv_vr, val, &sop); |
| if (t) |
| { |
| /* If we get different answers from different members |
| of the equivalence set this check must be in a dead |
| code region. Folding it to a trap representation |
| would be correct here. For now just return don't-know. */ |
| if (retval != NULL |
| && t != retval) |
| { |
| retval = NULL_TREE; |
| break; |
| } |
| retval = t; |
| |
| if (!sop) |
| used_strict_overflow = 0; |
| else if (used_strict_overflow < 0) |
| used_strict_overflow = 1; |
| } |
| } |
| |
| /* Remove VAR from its own equivalence set. */ |
| bitmap_clear_bit (e, SSA_NAME_VERSION (var)); |
| |
| if (retval) |
| { |
| if (used_strict_overflow > 0) |
| *strict_overflow_p = true; |
| return retval; |
| } |
| |
| /* We couldn't find a non-NULL value for the predicate. */ |
| return NULL_TREE; |
| } |
| |
| |
| /* Given a comparison code COMP and names N1 and N2, compare all the |
| ranges equivalent to N1 against all the ranges equivalent to N2 |
| to determine the value of N1 COMP N2. Return the same value |
| returned by compare_ranges. Set *STRICT_OVERFLOW_P to indicate |
| whether we relied on an overflow infinity in the comparison. */ |
| |
| |
| static tree |
| compare_names (enum tree_code comp, tree n1, tree n2, |
| bool *strict_overflow_p) |
| { |
| tree t, retval; |
| bitmap e1, e2; |
| bitmap_iterator bi1, bi2; |
| unsigned i1, i2; |
| int used_strict_overflow; |
| |
| /* Compare the ranges of every name equivalent to N1 against the |
| ranges of every name equivalent to N2. */ |
| e1 = get_value_range (n1)->equiv; |
| e2 = get_value_range (n2)->equiv; |
| |
| /* Add N1 and N2 to their own set of equivalences to avoid |
| duplicating the body of the loop just to check N1 and N2 |
| ranges. */ |
| bitmap_set_bit (e1, SSA_NAME_VERSION (n1)); |
| bitmap_set_bit (e2, SSA_NAME_VERSION (n2)); |
| |
| /* If the equivalence sets have a common intersection, then the two |
| names can be compared without checking their ranges. */ |
| if (bitmap_intersect_p (e1, e2)) |
| { |
| bitmap_clear_bit (e1, SSA_NAME_VERSION (n1)); |
| bitmap_clear_bit (e2, SSA_NAME_VERSION (n2)); |
| |
| return (comp == EQ_EXPR || comp == GE_EXPR || comp == LE_EXPR) |
| ? boolean_true_node |
| : boolean_false_node; |
| } |
| |
| /* Start at -1. Set it to 0 if we do a comparison without relying |
| on overflow, or 1 if all comparisons rely on overflow. */ |
| used_strict_overflow = -1; |
| |
| /* Otherwise, compare all the equivalent ranges. First, add N1 and |
| N2 to their own set of equivalences to avoid duplicating the body |
| of the loop just to check N1 and N2 ranges. */ |
| EXECUTE_IF_SET_IN_BITMAP (e1, 0, i1, bi1) |
| { |
| value_range_t vr1 = *(vr_value[i1]); |
| |
| /* If the range is VARYING or UNDEFINED, use the name itself. */ |
| if (vr1.type == VR_VARYING || vr1.type == VR_UNDEFINED) |
| { |
| vr1.type = VR_RANGE; |
| vr1.min = ssa_name (i1); |
| vr1.max = ssa_name (i1); |
| } |
| |
| t = retval = NULL_TREE; |
| EXECUTE_IF_SET_IN_BITMAP (e2, 0, i2, bi2) |
| { |
| bool sop = false; |
| |
| value_range_t vr2 = *(vr_value[i2]); |
| |
| if (vr2.type == VR_VARYING || vr2.type == VR_UNDEFINED) |
| { |
| vr2.type = VR_RANGE; |
| vr2.min = ssa_name (i2); |
| vr2.max = ssa_name (i2); |
| } |
| |
| t = compare_ranges (comp, &vr1, &vr2, &sop); |
| if (t) |
| { |
| /* If we get different answers from different members |
| of the equivalence set this check must be in a dead |
| code region. Folding it to a trap representation |
| would be correct here. For now just return don't-know. */ |
| if (retval != NULL |
| && t != retval) |
| { |
| bitmap_clear_bit (e1, SSA_NAME_VERSION (n1)); |
| bitmap_clear_bit (e2, SSA_NAME_VERSION (n2)); |
| return NULL_TREE; |
| } |
| retval = t; |
| |
| if (!sop) |
| used_strict_overflow = 0; |
| else if (used_strict_overflow < 0) |
| used_strict_overflow = 1; |
| } |
| } |
| |
| if (retval) |
| { |
| bitmap_clear_bit (e1, SSA_NAME_VERSION (n1)); |
| bitmap_clear_bit (e2, SSA_NAME_VERSION (n2)); |
| if (used_strict_overflow > 0) |
| *strict_overflow_p = true; |
| return retval; |
| } |
| } |
| |
| /* None of the equivalent ranges are useful in computing this |
| comparison. */ |
| bitmap_clear_bit (e1, SSA_NAME_VERSION (n1)); |
| bitmap_clear_bit (e2, SSA_NAME_VERSION (n2)); |
| return NULL_TREE; |
| } |
| |
| |
| /* Given a conditional predicate COND, try to determine if COND yields |
| true or false based on the value ranges of its operands. Return |
| BOOLEAN_TRUE_NODE if the conditional always evaluates to true, |
| BOOLEAN_FALSE_NODE if the conditional always evaluates to false, and, |
| NULL if the conditional cannot be evaluated at compile time. |
| |
| If USE_EQUIV_P is true, the ranges of all the names equivalent with |
| the operands in COND are used when trying to compute its value. |
| This is only used during final substitution. During propagation, |
| we only check the range of each variable and not its equivalents. |
| |
| Set *STRICT_OVERFLOW_P to indicate whether we relied on an overflow |
| infinity to produce the result. */ |
| |
| static tree |
| vrp_evaluate_conditional_warnv (tree cond, bool use_equiv_p, |
| bool *strict_overflow_p) |
| { |
| gcc_assert (TREE_CODE (cond) == SSA_NAME |
| || TREE_CODE_CLASS (TREE_CODE (cond)) == tcc_comparison); |
| |
| if (TREE_CODE (cond) == SSA_NAME) |
| { |
| value_range_t *vr; |
| tree retval; |
| |
| if (use_equiv_p) |
| retval = compare_name_with_value (NE_EXPR, cond, boolean_false_node, |
| strict_overflow_p); |
| else |
| { |
| value_range_t *vr = get_value_range (cond); |
| retval = compare_range_with_value (NE_EXPR, vr, boolean_false_node, |
| strict_overflow_p); |
| } |
| |
| /* If COND has a known boolean range, return it. */ |
| if (retval) |
| return retval; |
| |
| /* Otherwise, if COND has a symbolic range of exactly one value, |
| return it. */ |
| vr = get_value_range (cond); |
| if (vr->type == VR_RANGE && vr->min == vr->max) |
| return vr->min; |
| } |
| else |
| { |
| tree op0 = TREE_OPERAND (cond, 0); |
| tree op1 = TREE_OPERAND (cond, 1); |
| |
| /* We only deal with integral and pointer types. */ |
| if (!INTEGRAL_TYPE_P (TREE_TYPE (op0)) |
| && !POINTER_TYPE_P (TREE_TYPE (op0))) |
| return NULL_TREE; |
| |
| if (use_equiv_p) |
| { |
| if (TREE_CODE (op0) == SSA_NAME && TREE_CODE (op1) == SSA_NAME) |
| return compare_names (TREE_CODE (cond), op0, op1, |
| strict_overflow_p); |
| else if (TREE_CODE (op0) == SSA_NAME) |
| return compare_name_with_value (TREE_CODE (cond), op0, op1, |
| strict_overflow_p); |
| else if (TREE_CODE (op1) == SSA_NAME) |
| return (compare_name_with_value |
| (swap_tree_comparison (TREE_CODE (cond)), op1, op0, |
| strict_overflow_p)); |
| } |
| else |
| { |
| value_range_t *vr0, *vr1; |
| |
| vr0 = (TREE_CODE (op0) == SSA_NAME) ? get_value_range (op0) : NULL; |
| vr1 = (TREE_CODE (op1) == SSA_NAME) ? get_value_range (op1) : NULL; |
| |
| if (vr0 && vr1) |
| return compare_ranges (TREE_CODE (cond), vr0, vr1, |
| strict_overflow_p); |
| else if (vr0 && vr1 == NULL) |
| return compare_range_with_value (TREE_CODE (cond), vr0, op1, |
| strict_overflow_p); |
| else if (vr0 == NULL && vr1) |
| return (compare_range_with_value |
| (swap_tree_comparison (TREE_CODE (cond)), vr1, op0, |
| strict_overflow_p)); |
| } |
| } |
| |
| /* Anything else cannot be computed statically. */ |
| return NULL_TREE; |
| } |
| |
| /* Given COND within STMT, try to simplify it based on value range |
| information. Return NULL if the conditional can not be evaluated. |
| The ranges of all the names equivalent with the operands in COND |
| will be used when trying to compute the value. If the result is |
| based on undefined signed overflow, issue a warning if |
| appropriate. */ |
| |
| tree |
| vrp_evaluate_conditional (tree cond, tree stmt) |
| { |
| bool sop; |
| tree ret; |
| |
| sop = false; |
| ret = vrp_evaluate_conditional_warnv (cond, true, &sop); |
| |
| if (ret && sop) |
| { |
| enum warn_strict_overflow_code wc; |
| const char* warnmsg; |
| |
| if (is_gimple_min_invariant (ret)) |
| { |
| wc = WARN_STRICT_OVERFLOW_CONDITIONAL; |
| warnmsg = G_("assuming signed overflow does not occur when " |
| "simplifying conditional to constant"); |
| } |
| else |
| { |
| wc = WARN_STRICT_OVERFLOW_COMPARISON; |
| warnmsg = G_("assuming signed overflow does not occur when " |
| "simplifying conditional"); |
| } |
| |
| if (issue_strict_overflow_warning (wc)) |
| { |
| location_t locus; |
| |
| if (!EXPR_HAS_LOCATION (stmt)) |
| locus = input_location; |
| else |
| locus = EXPR_LOCATION (stmt); |
| warning (OPT_Wstrict_overflow, "%H%s", &locus, warnmsg); |
| } |
| } |
| |
| return ret; |
| } |
| |
| |
| /* Visit conditional statement STMT. If we can determine which edge |
| will be taken out of STMT's basic block, record it in |
| *TAKEN_EDGE_P and return SSA_PROP_INTERESTING. Otherwise, return |
| SSA_PROP_VARYING. */ |
| |
| static enum ssa_prop_result |
| vrp_visit_cond_stmt (tree stmt, edge *taken_edge_p) |
| { |
| tree cond, val; |
| bool sop; |
| |
| *taken_edge_p = NULL; |
| |
| /* FIXME. Handle SWITCH_EXPRs. But first, the assert pass needs to |
| add ASSERT_EXPRs for them. */ |
| if (TREE_CODE (stmt) == SWITCH_EXPR) |
| return SSA_PROP_VARYING; |
| |
| cond = COND_EXPR_COND (stmt); |
| |
| if (dump_file && (dump_flags & TDF_DETAILS)) |
| { |
| tree use; |
| ssa_op_iter i; |
| |
| fprintf (dump_file, "\nVisiting conditional with predicate: "); |
| print_generic_expr (dump_file, cond, 0); |
| fprintf (dump_file, "\nWith known ranges\n"); |
| |
| FOR_EACH_SSA_TREE_OPERAND (use, stmt, i, SSA_OP_USE) |
| { |
| fprintf (dump_file, "\t"); |
| print_generic_expr (dump_file, use, 0); |
| fprintf (dump_file, ": "); |
| dump_value_range (dump_file, vr_value[SSA_NAME_VERSION (use)]); |
| } |
| |
| fprintf (dump_file, "\n"); |
| } |
| |
| /* Compute the value of the predicate COND by checking the known |
| ranges of each of its operands. |
| |
| Note that we cannot evaluate all the equivalent ranges here |
| because those ranges may not yet be final and with the current |
| propagation strategy, we cannot determine when the value ranges |
| of the names in the equivalence set have changed. |
| |
| For instance, given the following code fragment |
| |
| i_5 = PHI <8, i_13> |
| ... |
| i_14 = ASSERT_EXPR <i_5, i_5 != 0> |
| if (i_14 == 1) |
| ... |
| |
| Assume that on the first visit to i_14, i_5 has the temporary |
| range [8, 8] because the second argument to the PHI function is |
| not yet executable. We derive the range ~[0, 0] for i_14 and the |
| equivalence set { i_5 }. So, when we visit 'if (i_14 == 1)' for |
| the first time, since i_14 is equivalent to the range [8, 8], we |
| determine that the predicate is always false. |
| |
| On the next round of propagation, i_13 is determined to be |
| VARYING, which causes i_5 to drop down to VARYING. So, another |
| visit to i_14 is scheduled. In this second visit, we compute the |
| exact same range and equivalence set for i_14, namely ~[0, 0] and |
| { i_5 }. But we did not have the previous range for i_5 |
| registered, so vrp_visit_assignment thinks that the range for |
| i_14 has not changed. Therefore, the predicate 'if (i_14 == 1)' |
| is not visited again, which stops propagation from visiting |
| statements in the THEN clause of that if(). |
| |
| To properly fix this we would need to keep the previous range |
| value for the names in the equivalence set. This way we would've |
| discovered that from one visit to the other i_5 changed from |
| range [8, 8] to VR_VARYING. |
| |
| However, fixing this apparent limitation may not be worth the |
| additional checking. Testing on several code bases (GCC, DLV, |
| MICO, TRAMP3D and SPEC2000) showed that doing this results in |
| 4 more predicates folded in SPEC. */ |
| sop = false; |
| val = vrp_evaluate_conditional_warnv (cond, false, &sop); |
| if (val) |
| { |
| if (!sop) |
| *taken_edge_p = find_taken_edge (bb_for_stmt (stmt), val); |
| else |
| { |
| if (dump_file && (dump_flags & TDF_DETAILS)) |
| fprintf (dump_file, |
| "\nIgnoring predicate evaluation because " |
| "it assumes that signed overflow is undefined"); |
| val = NULL_TREE; |
| } |
| } |
| |
| if (dump_file && (dump_flags & TDF_DETAILS)) |
| { |
| fprintf (dump_file, "\nPredicate evaluates to: "); |
| if (val == NULL_TREE) |
| fprintf (dump_file, "DON'T KNOW\n"); |
| else |
| print_generic_stmt (dump_file, val, 0); |
| } |
| |
| return (*taken_edge_p) ? SSA_PROP_INTERESTING : SSA_PROP_VARYING; |
| } |
| |
| |
| /* Evaluate statement STMT. If the statement produces a useful range, |
| return SSA_PROP_INTERESTING and record the SSA name with the |
| interesting range into *OUTPUT_P. |
| |
| If STMT is a conditional branch and we can determine its truth |
| value, the taken edge is recorded in *TAKEN_EDGE_P. |
| |
| If STMT produces a varying value, return SSA_PROP_VARYING. */ |
| |
| static enum ssa_prop_result |
| vrp_visit_stmt (tree stmt, edge *taken_edge_p, tree *output_p) |
| { |
| tree def; |
| ssa_op_iter iter; |
| stmt_ann_t ann; |
| |
| if (dump_file && (dump_flags & TDF_DETAILS)) |
| { |
| fprintf (dump_file, "\nVisiting statement:\n"); |
| print_generic_stmt (dump_file, stmt, dump_flags); |
| fprintf (dump_file, "\n"); |
| } |
| |
| ann = stmt_ann (stmt); |
| if (TREE_CODE (stmt) == MODIFY_EXPR) |
| { |
| tree rhs = TREE_OPERAND (stmt, 1); |
| |
| /* In general, assignments with virtual operands are not useful |
| for deriving ranges, with the obvious exception of calls to |
| builtin functions. */ |
| if ((TREE_CODE (rhs) == CALL_EXPR |
| && TREE_CODE (TREE_OPERAND (rhs, 0)) == ADDR_EXPR |
| && DECL_P (TREE_OPERAND (TREE_OPERAND (rhs, 0), 0)) |
| && DECL_IS_BUILTIN (TREE_OPERAND (TREE_OPERAND (rhs, 0), 0))) |
| || ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS)) |
| return vrp_visit_assignment (stmt, output_p); |
| } |
| else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR) |
| return vrp_visit_cond_stmt (stmt, taken_edge_p); |
| |
| /* All other statements produce nothing of interest for VRP, so mark |
| their outputs varying and prevent further simulation. */ |
| FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF) |
| set_value_range_to_varying (get_value_range (def)); |
| |
| return SSA_PROP_VARYING; |
| } |
| |
| |
| /* Meet operation for value ranges. Given two value ranges VR0 and |
| VR1, store in VR0 the result of meeting VR0 and VR1. |
| |
| The meeting rules are as follows: |
| |
| 1- If VR0 and VR1 have an empty intersection, set VR0 to VR_VARYING. |
| |
| 2- If VR0 and VR1 have a non-empty intersection, set VR0 to the |
| union of VR0 and VR1. */ |
| |
| static void |
| vrp_meet (value_range_t *vr0, value_range_t *vr1) |
| { |
| if (vr0->type == VR_UNDEFINED) |
| { |
| copy_value_range (vr0, vr1); |
| return; |
| } |
| |
| if (vr1->type == VR_UNDEFINED) |
| { |
| /* Nothing to do. VR0 already has the resulting range. */ |
| return; |
| } |
| |
| if (vr0->type == VR_VARYING) |
| { |
| /* Nothing to do. VR0 already has the resulting range. */ |
| return; |
| } |
| |
| if (vr1->type == VR_VARYING) |
| { |
| set_value_range_to_varying (vr0); |
| return; |
| } |
| |
| if (vr0->type == VR_RANGE && vr1->type == VR_RANGE) |
| { |
| /* If VR0 and VR1 have a non-empty intersection, compute the |
| union of both ranges. */ |
| if (value_ranges_intersect_p (vr0, vr1)) |
| { |
| int cmp; |
| tree min, max; |
| |
| /* The lower limit of the new range is the minimum of the |
| two ranges. If they cannot be compared, the result is |
| VARYING. */ |
| cmp = compare_values (vr0->min, vr1->min); |
| if (cmp == 0 || cmp == 1) |
| min = vr1->min; |
| else if (cmp == -1) |
| min = vr0->min; |
| else |
| { |
| set_value_range_to_varying (vr0); |
| return; |
| } |
| |
| /* Similarly, the upper limit of the new range is the |
| maximum of the two ranges. If they cannot be compared, |
| the result is VARYING. */ |
| cmp = compare_values (vr0->max, vr1->max); |
| if (cmp == 0 || cmp == -1) |
| max = vr1->max; |
| else if (cmp == 1) |
| max = vr0->max; |
| else |
| { |
| set_value_range_to_varying (vr0); |
| return; |
| } |
| |
| /* Check for useless ranges. */ |
| if (INTEGRAL_TYPE_P (TREE_TYPE (min)) |
| && ((vrp_val_is_min (min) || is_overflow_infinity (min)) |
| && (vrp_val_is_max (max) || is_overflow_infinity (max)))) |
| { |
| set_value_range_to_varying (vr0); |
| return; |
| } |
| |
| /* The resulting set of equivalences is the intersection of |
| the two sets. */ |
| if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv) |
| bitmap_and_into (vr0->equiv, vr1->equiv); |
| else if (vr0->equiv && !vr1->equiv) |
| bitmap_clear (vr0->equiv); |
| |
| set_value_range (vr0, vr0->type, min, max, vr0->equiv); |
| } |
| else |
| goto no_meet; |
| } |
| else if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE) |
| { |
| /* Two anti-ranges meet only if they are both identical. */ |
| if (compare_values (vr0->min, vr1->min) == 0 |
| && compare_values (vr0->max, vr1->max) == 0 |
| && compare_values (vr0->min, vr0->max) == 0) |
| { |
| /* The resulting set of equivalences is the intersection of |
| the two sets. */ |
| if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv) |
| bitmap_and_into (vr0->equiv, vr1->equiv); |
| else if (vr0->equiv && !vr1->equiv) |
| bitmap_clear (vr0->equiv); |
| } |
| else |
| goto no_meet; |
| } |
| else if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE) |
| { |
| /* A numeric range [VAL1, VAL2] and an anti-range ~[VAL3, VAL4] |
| meet only if the ranges have an empty intersection. The |
| result of the meet operation is the anti-range. */ |
| if (!symbolic_range_p (vr0) |
| && !symbolic_range_p (vr1) |
| && !value_ranges_intersect_p (vr0, vr1)) |
| { |
| /* Copy most of VR1 into VR0. Don't copy VR1's equivalence |
| set. We need to compute the intersection of the two |
| equivalence sets. */ |
| if (vr1->type == VR_ANTI_RANGE) |
| set_value_range (vr0, vr1->type, vr1->min, vr1->max, vr0->equiv); |
| |
| /* The resulting set of equivalences is the intersection of |
| the two sets. */ |
| if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv) |
| bitmap_and_into (vr0->equiv, vr1->equiv); |
| else if (vr0->equiv && !vr1->equiv) |
| bitmap_clear (vr0->equiv); |
| } |
| else |
| goto no_meet; |
| } |
| else |
| gcc_unreachable (); |
| |
| return; |
| |
| no_meet: |
| /* The two range VR0 and VR1 do not meet. Before giving up and |
| setting the result to VARYING, see if we can at least derive a |
| useful anti-range. FIXME, all this nonsense about distinguishing |
| anti-ranges from ranges is necessary because of the odd |
| semantics of range_includes_zero_p and friends. */ |
| if (!symbolic_range_p (vr0) |
| && ((vr0->type == VR_RANGE && !range_includes_zero_p (vr0)) |
| || (vr0->type == VR_ANTI_RANGE && range_includes_zero_p (vr0))) |
| && !symbolic_range_p (vr1) |
| && ((vr1->type == VR_RANGE && !range_includes_zero_p (vr1)) |
| || (vr1->type == VR_ANTI_RANGE && range_includes_zero_p (vr1)))) |
| { |
| set_value_range_to_nonnull (vr0, TREE_TYPE (vr0->min)); |
| |
| /* Since this meet operation did not result from the meeting of |
| two equivalent names, VR0 cannot have any equivalences. */ |
| if (vr0->equiv) |
| bitmap_clear (vr0->equiv); |
| } |
| else |
| set_value_range_to_varying (vr0); |
| } |
| |
| |
| /* Visit all arguments for PHI node PHI that flow through executable |
| edges. If a valid value range can be derived from all the incoming |
| value ranges, set a new range for the LHS of PHI. */ |
| |
| static enum ssa_prop_result |
| vrp_visit_phi_node (tree phi) |
| { |
| int i; |
| tree lhs = PHI_RESULT (phi); |
| value_range_t *lhs_vr = get_value_range (lhs); |
| value_range_t vr_result = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL }; |
| |
| copy_value_range (&vr_result, lhs_vr); |
| |
| if (dump_file && (dump_flags & TDF_DETAILS)) |
| { |
| fprintf (dump_file, "\nVisiting PHI node: "); |
| print_generic_expr (dump_file, phi, dump_flags); |
| } |
| |
| for (i = 0; i < PHI_NUM_ARGS (phi); i++) |
| { |
| edge e = PHI_ARG_EDGE (phi, i); |
| |
| if (dump_file && (dump_flags & TDF_DETAILS)) |
| { |
| fprintf (dump_file, |
| "\n Argument #%d (%d -> %d %sexecutable)\n", |
| i, e->src->index, e->dest->index, |
| (e->flags & EDGE_EXECUTABLE) ? "" : "not "); |
| } |
| |
| if (e->flags & EDGE_EXECUTABLE) |
| { |
| tree arg = PHI_ARG_DEF (phi, i); |
| value_range_t vr_arg; |
| |
| if (TREE_CODE (arg) == SSA_NAME) |
| vr_arg = *(get_value_range (arg)); |
| else |
| { |
| if (is_overflow_infinity (arg)) |
| { |
| arg = copy_node (arg); |
| TREE_OVERFLOW (arg) = 0; |
| } |
| |
| vr_arg.type = VR_RANGE; |
| vr_arg.min = arg; |
| vr_arg.max = arg; |
| vr_arg.equiv = NULL; |
| } |
| |
| if (dump_file && (dump_flags & TDF_DETAILS)) |
| { |
| fprintf (dump_file, "\t"); |
| print_generic_expr (dump_file, arg, dump_flags); |
| fprintf (dump_file, "\n\tValue: "); |
| dump_value_range (dump_file, &vr_arg); |
| fprintf (dump_file, "\n"); |
| } |
| |
| vrp_meet (&vr_result, &vr_arg); |
| |
| if (vr_result.type == VR_VARYING) |
| break; |
| } |
| } |
| |
| if (vr_result.type == VR_VARYING) |
| goto varying; |
| |
| /* To prevent infinite iterations in the algorithm, derive ranges |
| when the new value is slightly bigger or smaller than the |
| previous one. */ |
| if (lhs_vr->type == VR_RANGE && vr_result.type == VR_RANGE) |
| { |
| if (!POINTER_TYPE_P (TREE_TYPE (lhs))) |
| { |
| int cmp_min = compare_values (lhs_vr->min, vr_result.min); |
| int cmp_max = compare_values (lhs_vr->max, vr_result.max); |
| |
| /* If the new minimum is smaller or larger than the previous |
| one, go all the way to -INF. In the first case, to avoid |
| iterating millions of times to reach -INF, and in the |
| other case to avoid infinite bouncing between different |
| minimums. */ |
| if (cmp_min > 0 || cmp_min < 0) |
| { |
| /* If we will end up with a (-INF, +INF) range, set it |
| to VARYING. */ |
| if (vrp_val_is_max (vr_result.max)) |
| goto varying; |
| |
| if (!needs_overflow_infinity (TREE_TYPE (vr_result.min)) |
| || !vrp_var_may_overflow (lhs, phi)) |
| vr_result.min = TYPE_MIN_VALUE (TREE_TYPE (vr_result.min)); |
| else if (supports_overflow_infinity (TREE_TYPE (vr_result.min))) |
| vr_result.min = |
| negative_overflow_infinity (TREE_TYPE (vr_result.min)); |
| else |
| goto varying; |
| } |
| |
| /* Similarly, if the new maximum is smaller or larger than |
| the previous one, go all the way to +INF. */ |
| if (cmp_max < 0 || cmp_max > 0) |
| { |
| /* If we will end up with a (-INF, +INF) range, set it |
| to VARYING. */ |
| if (vrp_val_is_min (vr_result.min)) |
| goto varying; |
| |
| if (!needs_overflow_infinity (TREE_TYPE (vr_result.max)) |
| || !vrp_var_may_overflow (lhs, phi)) |
| vr_result.max = TYPE_MAX_VALUE (TREE_TYPE (vr_result.max)); |
| else if (supports_overflow_infinity (TREE_TYPE (vr_result.max))) |
| vr_result.max = |
| positive_overflow_infinity (TREE_TYPE (vr_result.max)); |
| else |
| goto varying; |
| } |
| } |
| } |
| |
| /* If the new range is different than the previous value, keep |
| iterating. */ |
| if (update_value_range (lhs, &vr_result)) |
| return SSA_PROP_INTERESTING; |
| |
| /* Nothing changed, don't add outgoing edges. */ |
| return SSA_PROP_NOT_INTERESTING; |
| |
| /* No match found. Set the LHS to VARYING. */ |
| varying: |
| set_value_range_to_varying (lhs_vr); |
| return SSA_PROP_VARYING; |
| } |
| |
| /* Simplify a division or modulo operator to a right shift or |
| bitwise and if the first operand is unsigned or is greater |
| than zero and the second operand is an exact power of two. */ |
| |
| static void |
| simplify_div_or_mod_using_ranges (tree stmt, tree rhs, enum tree_code rhs_code) |
| { |
| tree val = NULL; |
| tree op = TREE_OPERAND (rhs, 0); |
| value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0)); |
| |
| if (TYPE_UNSIGNED (TREE_TYPE (op))) |
| { |
| val = integer_one_node; |
| } |
| else |
| { |
| bool sop = false; |
| |
| val = compare_range_with_value (GT_EXPR, vr, integer_zero_node, &sop); |
| |
| if (val |
| && sop |
| && integer_onep (val) |
| && issue_strict_overflow_warning (WARN_STRICT_OVERFLOW_MISC)) |
| { |
| location_t locus; |
| |
| if (!EXPR_HAS_LOCATION (stmt)) |
| locus = input_location; |
| else |
| locus = EXPR_LOCATION (stmt); |
| warning (OPT_Wstrict_overflow, |
| ("%Hassuming signed overflow does not occur when " |
| "simplifying / or %% to >> or &"), |
| &locus); |
| } |
| } |
| |
| if (val && integer_onep (val)) |
| { |
| tree t; |
| tree op0 = TREE_OPERAND (rhs, 0); |
| tree op1 = TREE_OPERAND (rhs, 1); |
| |
| if (rhs_code == TRUNC_DIV_EXPR) |
| { |
| t = build_int_cst (NULL_TREE, tree_log2 (op1)); |
| t = build2 (RSHIFT_EXPR, TREE_TYPE (op0), op0, t); |
| } |
| else |
| { |
| t = build_int_cst (TREE_TYPE (op1), 1); |
| t = int_const_binop (MINUS_EXPR, op1, t, 0); |
| t = fold_convert (TREE_TYPE (op0), t); |
| t = build2 (BIT_AND_EXPR, TREE_TYPE (op0), op0, t); |
| } |
| |
| TREE_OPERAND (stmt, 1) = t; |
| update_stmt (stmt); |
| } |
| } |
| |
| /* If the operand to an ABS_EXPR is >= 0, then eliminate the |
| ABS_EXPR. If the operand is <= 0, then simplify the |
| ABS_EXPR into a NEGATE_EXPR. */ |
| |
| static void |
| simplify_abs_using_ranges (tree stmt, tree rhs) |
| { |
| tree val = NULL; |
| tree op = TREE_OPERAND (rhs, 0); |
| tree type = TREE_TYPE (op); |
| value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0)); |
| |
| if (TYPE_UNSIGNED (type)) |
| { |
| val = integer_zero_node; |
| } |
| else if (vr) |
| { |
| bool sop = false; |
| |
| val = compare_range_with_value (LE_EXPR, vr, integer_zero_node, &sop); |
| if (!val) |
| { |
| sop = false; |
| val = compare_range_with_value (GE_EXPR, vr, integer_zero_node, |
| &sop); |
| |
| if (val) |
| { |
| if (integer_zerop (val)) |
| val = integer_one_node; |
| else if (integer_onep (val)) |
| val = integer_zero_node; |
| } |
| } |
| |
| if (val |
| && (integer_onep (val) || integer_zerop (val))) |
| { |
| tree t; |
| |
| if (sop && issue_strict_overflow_warning (WARN_STRICT_OVERFLOW_MISC)) |
| { |
| location_t locus; |
| |
| if (!EXPR_HAS_LOCATION (stmt)) |
| locus = input_location; |
| else |
| locus = EXPR_LOCATION (stmt); |
| warning (OPT_Wstrict_overflow, |
| ("%Hassuming signed overflow does not occur when " |
| "simplifying abs (X) to X or -X"), |
| &locus); |
| } |
| |
| if (integer_onep (val)) |
| t = build1 (NEGATE_EXPR, TREE_TYPE (op), op); |
| else |
| t = op; |
| |
| TREE_OPERAND (stmt, 1) = t; |
| update_stmt (stmt); |
| } |
| } |
| } |
| |
| /* We are comparing trees OP0 and OP1 using COND_CODE. OP0 has |
| a known value range VR. |
| |
| If there is one and only one value which will satisfy the |
| conditional, then return that value. Else return NULL. */ |
| |
| static tree |
| test_for_singularity (enum tree_code cond_code, tree op0, |
| tree op1, value_range_t *vr) |
| { |
| tree min = NULL; |
| tree max = NULL; |
| |
| /* Extract minimum/maximum values which satisfy the |
| the conditional as it was written. */ |
| if (cond_code == LE_EXPR || cond_code == LT_EXPR) |
| { |
| /* This should not be negative infinity; there is no overflow |
| here. */ |
| min = TYPE_MIN_VALUE (TREE_TYPE (op0)); |
| |
| max = op1; |
| if (cond_code == LT_EXPR && !is_overflow_infinity (max)) |
| { |
| tree one = build_int_cst (TREE_TYPE (op0), 1); |
| max = fold_build2 (MINUS_EXPR, TREE_TYPE (op0), max, one); |
| if (EXPR_P (max)) |
| TREE_NO_WARNING (max) = 1; |
| } |
| } |
| else if (cond_code == GE_EXPR || cond_code == GT_EXPR) |
| { |
| /* This should not be positive infinity; there is no overflow |
| here. */ |
| max = TYPE_MAX_VALUE (TREE_TYPE (op0)); |
| |
| min = op1; |
| if (cond_code == GT_EXPR && !is_overflow_infinity (min)) |
| { |
| tree one = build_int_cst (TREE_TYPE (op0), 1); |
| min = fold_build2 (PLUS_EXPR, TREE_TYPE (op0), min, one); |
| if (EXPR_P (min)) |
| TREE_NO_WARNING (min) = 1; |
| } |
| } |
| |
| /* Now refine the minimum and maximum values using any |
| value range information we have for op0. */ |
| if (min && max) |
| { |
| if (compare_values (vr->min, min) == -1) |
| min = min; |
| else |
| min = vr->min; |
| if (compare_values (vr->max, max) == 1) |
| max = max; |
| else |
| max = vr->max; |
| |
| /* If the new min/max values have converged to a single value, |
| then there is only one value which can satisfy the condition, |
| return that value. */ |
| if (operand_equal_p (min, max, 0) && is_gimple_min_invariant (min)) |
| return min; |
| } |
| return NULL; |
| } |
| |
| /* Simplify a conditional using a relational operator to an equality |
| test if the range information indicates only one value can satisfy |
| the original conditional. */ |
| |
| static void |
| simplify_cond_using_ranges (tree stmt) |
| { |
| tree cond = COND_EXPR_COND (stmt); |
| tree op0 = TREE_OPERAND (cond, 0); |
| tree op1 = TREE_OPERAND (cond, 1); |
| enum tree_code cond_code = TREE_CODE (cond); |
| |
| if (cond_code != NE_EXPR |
| && cond_code != EQ_EXPR |
| && TREE_CODE (op0) == SSA_NAME |
| && INTEGRAL_TYPE_P (TREE_TYPE (op0)) |
| && is_gimple_min_invariant (op1)) |
| { |
| value_range_t *vr = get_value_range (op0); |
| |
| /* If we have range information for OP0, then we might be |
| able to simplify this conditional. */ |
| if (vr->type == VR_RANGE) |
| { |
| tree new = test_for_singularity (cond_code, op0, op1, vr); |
| |
| if (new) |
| { |
| if (dump_file) |
| { |
| fprintf (dump_file, "Simplified relational "); |
| print_generic_expr (dump_file, cond, 0); |
| fprintf (dump_file, " into "); |
| } |
| |
| COND_EXPR_COND (stmt) |
| = build2 (EQ_EXPR, boolean_type_node, op0, new); |
| update_stmt (stmt); |
| |
| if (dump_file) |
| { |
| print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0); |
| fprintf (dump_file, "\n"); |
| } |
| return; |
| |
| } |
| |
| /* Try again after inverting the condition. We only deal |
| with integral types here, so no need to worry about |
| issues with inverting FP comparisons. */ |
| cond_code = invert_tree_comparison (cond_code, false); |
| new = test_for_singularity (cond_code, op0, op1, vr); |
| |
| if (new) |
| { |
| if (dump_file) |
| { |
| fprintf (dump_file, "Simplified relational "); |
| print_generic_expr (dump_file, cond, 0); |
| fprintf (dump_file, " into "); |
| } |
| |
| COND_EXPR_COND (stmt) |
| = build2 (NE_EXPR, boolean_type_node, op0, new); |
| update_stmt (stmt); |
| |
| if (dump_file) |
| { |
| print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0); |
| fprintf (dump_file, "\n"); |
| } |
| return; |
| |
| } |
| } |
| } |
| } |
| |
| /* Simplify STMT using ranges if possible. */ |
| |
| void |
| simplify_stmt_using_ranges (tree stmt) |
| { |
| if (TREE_CODE (stmt) == MODIFY_EXPR) |
| { |
| tree rhs = TREE_OPERAND (stmt, 1); |
| enum tree_code rhs_code = TREE_CODE (rhs); |
| |
| /* Transform TRUNC_DIV_EXPR and TRUNC_MOD_EXPR into RSHIFT_EXPR |
| and BIT_AND_EXPR respectively if the first operand is greater |
| than zero and the second operand is an exact power of two. */ |
| if ((rhs_code == TRUNC_DIV_EXPR || rhs_code == TRUNC_MOD_EXPR) |
| && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0))) |
| && integer_pow2p (TREE_OPERAND (rhs, 1))) |
| simplify_div_or_mod_using_ranges (stmt, rhs, rhs_code); |
| |
| /* Transform ABS (X) into X or -X as appropriate. */ |
| if (rhs_code == ABS_EXPR |
| && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME |
| && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0)))) |
| simplify_abs_using_ranges (stmt, rhs); |
| } |
| else if (TREE_CODE (stmt) == COND_EXPR |
| && COMPARISON_CLASS_P (COND_EXPR_COND (stmt))) |
| { |
| simplify_cond_using_ranges (stmt); |
| } |
| } |
| |
| /* Stack of dest,src equivalency pairs that need to be restored after |
| each attempt to thread a block's incoming edge to an outgoing edge. |
| |
| A NULL entry is used to mark the end of pairs which need to be |
| restored. */ |
| static VEC(tree,heap) *stack; |
| |
| /* A trivial wrapper so that we can present the generic jump threading |
| code with a simple API for simplifying statements. STMT is the |
| statement we want to simplify, WITHIN_STMT provides the location |
| for any overflow warnings. */ |
| |
| static tree |
| simplify_stmt_for_jump_threading (tree stmt, tree within_stmt) |
| { |
| /* We only use VRP information to simplify conditionals. This is |
| overly conservative, but it's unclear if doing more would be |
| worth the compile time cost. */ |
| if (TREE_CODE (stmt) != COND_EXPR) |
| return NULL; |
| |
| return vrp_evaluate_conditional (COND_EXPR_COND (stmt), within_stmt); |
| } |
| |
| /* Blocks which have more than one predecessor and more than |
| one successor present jump threading opportunities. ie, |
| when the block is reached from a specific predecessor, we |
| may be able to determine which of the outgoing edges will |
| be traversed. When this optimization applies, we are able |
| to avoid conditionals at runtime and we may expose secondary |
| optimization opportunities. |
| |
| This routine is effectively a driver for the generic jump |
| threading code. It basically just presents the generic code |
| with edges that may be suitable for jump threading. |
| |
| Unlike DOM, we do not iterate VRP if jump threading was successful. |
| While iterating may expose new opportunities for VRP, it is expected |
| those opportunities would be very limited and the compile time cost |
| to expose those opportunities would be significant. |
| |
| As jump threading opportunities are discovered, they are registered |
| for later realization. */ |
| |
| static void |
| identify_jump_threads (void) |
| { |
| basic_block bb; |
| tree dummy; |
| |
| /* Ugh. When substituting values earlier in this pass we can |
| wipe the dominance information. So rebuild the dominator |
| information as we need it within the jump threading code. */ |
| calculate_dominance_info (CDI_DOMINATORS); |
| |
| /* We do not allow VRP information to be used for jump threading |
| across a back edge in the CFG. Otherwise it becomes too |
| difficult to avoid eliminating loop exit tests. Of course |
| EDGE_DFS_BACK is not accurate at this time so we have to |
| recompute it. */ |
| mark_dfs_back_edges (); |
| |
| /* Allocate our unwinder stack to unwind any temporary equivalences |
| that might be recorded. */ |
| stack = VEC_alloc (tree, heap, 20); |
| |
| /* To avoid lots of silly node creation, we create a single |
| conditional and just modify it in-place when attempting to |
| thread jumps. */ |
| dummy = build2 (EQ_EXPR, boolean_type_node, NULL, NULL); |
| dummy = build3 (COND_EXPR, void_type_node, dummy, NULL, NULL); |
| |
| /* Walk through all the blocks finding those which present a |
| potential jump threading opportunity. We could set this up |
| as a dominator walker and record data during the walk, but |
| I doubt it's worth the effort for the classes of jump |
| threading opportunities we are trying to identify at this |
| point in compilation. */ |
| FOR_EACH_BB (bb) |
| { |
| tree last, cond; |
| |
| /* If the generic jump threading code does not find this block |
| interesting, then there is nothing to do. */ |
| if (! potentially_threadable_block (bb)) |
| continue; |
| |
| /* We only care about blocks ending in a COND_EXPR. While there |
| may be some value in handling SWITCH_EXPR here, I doubt it's |
| terribly important. */ |
| last = bsi_stmt (bsi_last (bb)); |
| if (TREE_CODE (last) != COND_EXPR) |
| continue; |
| |
| /* We're basically looking for any kind of conditional with |
| integral type arguments. */ |
| cond = COND_EXPR_COND (last); |
| if ((TREE_CODE (cond) == SSA_NAME |
| && INTEGRAL_TYPE_P (TREE_TYPE (cond))) |
| || (COMPARISON_CLASS_P (cond) |
| && TREE_CODE (TREE_OPERAND (cond, 0)) == SSA_NAME |
| && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond, 0))) |
| && (TREE_CODE (TREE_OPERAND (cond, 1)) == SSA_NAME |
| || is_gimple_min_invariant (TREE_OPERAND (cond, 1))) |
| && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond, 1))))) |
| { |
| edge_iterator ei; |
| edge e; |
| |
| /* We've got a block with multiple predecessors and multiple |
| successors which also ends in a suitable conditional. For |
| each predecessor, see if we can thread it to a specific |
| successor. */ |
| FOR_EACH_EDGE (e, ei, bb->preds) |
| { |
| /* Do not thread across back edges or abnormal edges |
| in the CFG. */ |
| if (e->flags & (EDGE_DFS_BACK | EDGE_COMPLEX)) |
| continue; |
| |
| thread_across_edge (dummy, e, true, |
| &stack, |
| simplify_stmt_for_jump_threading); |
| } |
| } |
| } |
| |
| /* We do not actually update the CFG or SSA graphs at this point as |
| ASSERT_EXPRs are still in the IL and cfg cleanup code does not yet |
| handle ASSERT_EXPRs gracefully. */ |
| } |
| |
| /* We identified all the jump threading opportunities earlier, but could |
| not transform the CFG at that time. This routine transforms the |
| CFG and arranges for the dominator tree to be rebuilt if necessary. |
| |
| Note the SSA graph update will occur during the normal TODO |
| processing by the pass manager. */ |
| static void |
| finalize_jump_threads (void) |
| { |
| bool cfg_altered = false; |
| cfg_altered = thread_through_all_blocks (); |
| |
| /* If we threaded jumps, then we need to recompute the dominance |
| information, to safely do that we must clean up the CFG first. */ |
| if (cfg_altered) |
| { |
| free_dominance_info (CDI_DOMINATORS); |
| cleanup_tree_cfg (); |
| calculate_dominance_info (CDI_DOMINATORS); |
| } |
| VEC_free (tree, heap, stack); |
| } |
| |
| |
| /* Traverse all the blocks folding conditionals with known ranges. */ |
| |
| static void |
| vrp_finalize (void) |
| { |
| size_t i; |
| prop_value_t *single_val_range; |
| bool do_value_subst_p; |
| |
| if (dump_file) |
| { |
| fprintf (dump_file, "\nValue ranges after VRP:\n\n"); |
| dump_all_value_ranges (dump_file); |
| fprintf (dump_file, "\n"); |
| } |
| |
| /* We may have ended with ranges that have exactly one value. Those |
| values can be substituted as any other copy/const propagated |
| value using substitute_and_fold. */ |
| single_val_range = XNEWVEC (prop_value_t, num_ssa_names); |
| memset (single_val_range, 0, num_ssa_names * sizeof (*single_val_range)); |
| |
| do_value_subst_p = false; |
| for (i = 0; i < num_ssa_names; i++) |
| if (vr_value[i] |
| && vr_value[i]->type == VR_RANGE |
| && vr_value[i]->min == vr_value[i]->max) |
| { |
| single_val_range[i].value = vr_value[i]->min; |
| do_value_subst_p = true; |
| } |
| |
| if (!do_value_subst_p) |
| { |
| /* We found no single-valued ranges, don't waste time trying to |
| do single value substitution in substitute_and_fold. */ |
| free (single_val_range); |
| single_val_range = NULL; |
| } |
| |
| substitute_and_fold (single_val_range, true); |
| |
| /* We must identify jump threading opportunities before we release |
| the datastructures built by VRP. */ |
| identify_jump_threads (); |
| |
| /* Free allocated memory. */ |
| for (i = 0; i < num_ssa_names; i++) |
| if (vr_value[i]) |
| { |
| BITMAP_FREE (vr_value[i]->equiv); |
| free (vr_value[i]); |
| } |
| |
| free (single_val_range); |
| free (vr_value); |
| |
| /* So that we can distinguish between VRP data being available |
| and not available. */ |
| vr_value = NULL; |
| } |
| |
| |
| /* Main entry point to VRP (Value Range Propagation). This pass is |
| loosely based on J. R. C. Patterson, ``Accurate Static Branch |
| Prediction by Value Range Propagation,'' in SIGPLAN Conference on |
| Programming Language Design and Implementation, pp. 67-78, 1995. |
| Also available at http://citeseer.ist.psu.edu/patterson95accurate.html |
| |
| This is essentially an SSA-CCP pass modified to deal with ranges |
| instead of constants. |
| |
| While propagating ranges, we may find that two or more SSA name |
| have equivalent, though distinct ranges. For instance, |
| |
| 1 x_9 = p_3->a; |
| 2 p_4 = ASSERT_EXPR <p_3, p_3 != 0> |
| 3 if (p_4 == q_2) |
| 4 p_5 = ASSERT_EXPR <p_4, p_4 == q_2>; |
| 5 endif |
| 6 if (q_2) |
| |
| In the code above, pointer p_5 has range [q_2, q_2], but from the |
| code we can also determine that p_5 cannot be NULL and, if q_2 had |
| a non-varying range, p_5's range should also be compatible with it. |
| |
| These equivalences are created by two expressions: ASSERT_EXPR and |
| copy operations. Since p_5 is an assertion on p_4, and p_4 was the |
| result of another assertion, then we can use the fact that p_5 and |
| p_4 are equivalent when evaluating p_5's range. |
| |
| Together with value ranges, we also propagate these equivalences |
| between names so that we can take advantage of information from |
| multiple ranges when doing final replacement. Note that this |
| equivalency relation is transitive but not symmetric. |
| |
| In the example above, p_5 is equivalent to p_4, q_2 and p_3, but we |
| cannot assert that q_2 is equivalent to p_5 because q_2 may be used |
| in contexts where that assertion does not hold (e.g., in line 6). |
| |
| TODO, the main difference between this pass and Patterson's is that |
| we do not propagate edge probabilities. We only compute whether |
| edges can be taken or not. That is, instead of having a spectrum |
| of jump probabilities between 0 and 1, we only deal with 0, 1 and |
| DON'T KNOW. In the future, it may be worthwhile to propagate |
| probabilities to aid branch prediction. */ |
| |
| static unsigned int |
| execute_vrp (void) |
| { |
| insert_range_assertions (); |
| |
| current_loops = loop_optimizer_init (LOOPS_NORMAL); |
| if (current_loops) |
| scev_initialize (current_loops); |
| |
| vrp_initialize (); |
| ssa_propagate (vrp_visit_stmt, vrp_visit_phi_node); |
| vrp_finalize (); |
| |
| if (current_loops) |
| { |
| scev_finalize (); |
| loop_optimizer_finalize (current_loops); |
| current_loops = NULL; |
| } |
| |
| /* ASSERT_EXPRs must be removed before finalizing jump threads |
| as finalizing jump threads calls the CFG cleanup code which |
| does not properly handle ASSERT_EXPRs. */ |
| remove_range_assertions (); |
| |
| /* If we exposed any new variables, go ahead and put them into |
| SSA form now, before we handle jump threading. This simplifies |
| interactions between rewriting of _DECL nodes into SSA form |
| and rewriting SSA_NAME nodes into SSA form after block |
| duplication and CFG manipulation. */ |
| update_ssa (TODO_update_ssa); |
| |
| finalize_jump_threads (); |
| return 0; |
| } |
| |
| static bool |
| gate_vrp (void) |
| { |
| return flag_tree_vrp != 0; |
| } |
| |
| struct tree_opt_pass pass_vrp = |
| { |
| "vrp", /* name */ |
| gate_vrp, /* gate */ |
| execute_vrp, /* execute */ |
| NULL, /* sub */ |
| NULL, /* next */ |
| 0, /* static_pass_number */ |
| TV_TREE_VRP, /* tv_id */ |
| PROP_ssa | PROP_alias, /* properties_required */ |
| 0, /* properties_provided */ |
| PROP_smt_usage, /* properties_destroyed */ |
| 0, /* todo_flags_start */ |
| TODO_cleanup_cfg |
| | TODO_ggc_collect |
| | TODO_verify_ssa |
| | TODO_dump_func |
| | TODO_update_ssa |
| | TODO_update_smt_usage, /* todo_flags_finish */ |
| 0 /* letter */ |
| }; |