| /* SSA-PRE for trees. |
| Copyright (C) 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc. |
| Contributed by Daniel Berlin <dan@dberlin.org> and Steven Bosscher |
| <stevenb@suse.de> |
| |
| 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, 59 Temple Place - Suite 330, |
| Boston, MA 02111-1307, USA. */ |
| |
| #include "config.h" |
| #include "system.h" |
| #include "coretypes.h" |
| #include "tm.h" |
| #include "errors.h" |
| #include "ggc.h" |
| #include "tree.h" |
| #include "basic-block.h" |
| #include "diagnostic.h" |
| #include "tree-inline.h" |
| #include "tree-flow.h" |
| #include "tree-gimple.h" |
| #include "tree-dump.h" |
| #include "timevar.h" |
| #include "fibheap.h" |
| #include "hashtab.h" |
| #include "tree-iterator.h" |
| #include "real.h" |
| #include "alloc-pool.h" |
| #include "tree-pass.h" |
| #include "flags.h" |
| #include "bitmap.h" |
| #include "langhooks.h" |
| #include "cfgloop.h" |
| |
| /* TODO: |
| |
| 1. Avail sets can be shared by making an avail_find_leader that |
| walks up the dominator tree and looks in those avail sets. |
| This might affect code optimality, it's unclear right now. |
| 2. Load motion can be performed by value numbering the loads the |
| same as we do other expressions. This requires iterative |
| hashing the vuses into the values. Right now we simply assign |
| a new value every time we see a statement with a vuse. |
| 3. Strength reduction can be performed by anticipating expressions |
| we can repair later on. |
| 4. We can do back-substitution or smarter value numbering to catch |
| commutative expressions split up over multiple statements. |
| */ |
| |
| /* For ease of terminology, "expression node" in the below refers to |
| every expression node but MODIFY_EXPR, because MODIFY_EXPR's represent |
| the actual statement containing the expressions we care about, and |
| we cache the value number by putting it in the expression. */ |
| |
| /* Basic algorithm |
| |
| First we walk the statements to generate the AVAIL sets, the |
| EXP_GEN sets, and the tmp_gen sets. EXP_GEN sets represent the |
| generation of values/expressions by a given block. We use them |
| when computing the ANTIC sets. The AVAIL sets consist of |
| SSA_NAME's that represent values, so we know what values are |
| available in what blocks. AVAIL is a forward dataflow problem. In |
| SSA, values are never killed, so we don't need a kill set, or a |
| fixpoint iteration, in order to calculate the AVAIL sets. In |
| traditional parlance, AVAIL sets tell us the downsafety of the |
| expressions/values. |
| |
| Next, we generate the ANTIC sets. These sets represent the |
| anticipatable expressions. ANTIC is a backwards dataflow |
| problem.An expression is anticipatable in a given block if it could |
| be generated in that block. This means that if we had to perform |
| an insertion in that block, of the value of that expression, we |
| could. Calculating the ANTIC sets requires phi translation of |
| expressions, because the flow goes backwards through phis. We must |
| iterate to a fixpoint of the ANTIC sets, because we have a kill |
| set. Even in SSA form, values are not live over the entire |
| function, only from their definition point onwards. So we have to |
| remove values from the ANTIC set once we go past the definition |
| point of the leaders that make them up. |
| compute_antic/compute_antic_aux performs this computation. |
| |
| Third, we perform insertions to make partially redundant |
| expressions fully redundant. |
| |
| An expression is partially redundant (excluding partial |
| anticipation) if: |
| |
| 1. It is AVAIL in some, but not all, of the predecessors of a |
| given block. |
| 2. It is ANTIC in all the predecessors. |
| |
| In order to make it fully redundant, we insert the expression into |
| the predecessors where it is not available, but is ANTIC. |
| insert/insert_aux performs this insertion. |
| |
| Fourth, we eliminate fully redundant expressions. |
| This is a simple statement walk that replaces redundant |
| calculations with the now available values. */ |
| |
| /* Representations of value numbers: |
| |
| Value numbers are represented using the "value handle" approach. |
| This means that each SSA_NAME (and for other reasons to be |
| disclosed in a moment, expression nodes) has a value handle that |
| can be retrieved through get_value_handle. This value handle, *is* |
| the value number of the SSA_NAME. You can pointer compare the |
| value handles for equivalence purposes. |
| |
| For debugging reasons, the value handle is internally more than |
| just a number, it is a VAR_DECL named "value.x", where x is a |
| unique number for each value number in use. This allows |
| expressions with SSA_NAMES replaced by value handles to still be |
| pretty printed in a sane way. They simply print as "value.3 * |
| value.5", etc. |
| |
| Expression nodes have value handles associated with them as a |
| cache. Otherwise, we'd have to look them up again in the hash |
| table This makes significant difference (factor of two or more) on |
| some test cases. They can be thrown away after the pass is |
| finished. */ |
| |
| /* Representation of expressions on value numbers: |
| |
| In some portions of this code, you will notice we allocate "fake" |
| analogues to the expression we are value numbering, and replace the |
| operands with the values of the expression. Since we work on |
| values, and not just names, we canonicalize expressions to value |
| expressions for use in the ANTIC sets, the EXP_GEN set, etc. |
| |
| This is theoretically unnecessary, it just saves a bunch of |
| repeated get_value_handle and find_leader calls in the remainder of |
| the code, trading off temporary memory usage for speed. The tree |
| nodes aren't actually creating more garbage, since they are |
| allocated in a special pools which are thrown away at the end of |
| this pass. |
| |
| All of this also means that if you print the EXP_GEN or ANTIC sets, |
| you will see "value.5 + value.7" in the set, instead of "a_55 + |
| b_66" or something. The only thing that actually cares about |
| seeing the value leaders is phi translation, and it needs to be |
| able to find the leader for a value in an arbitrary block, so this |
| "value expression" form is perfect for it (otherwise you'd do |
| get_value_handle->find_leader->translate->get_value_handle->find_leader).*/ |
| |
| |
| /* Representation of sets: |
| |
| There are currently two types of sets used, hopefully to be unified soon. |
| The AVAIL sets do not need to be sorted in any particular order, |
| and thus, are simply represented as two bitmaps, one that keeps |
| track of values present in the set, and one that keeps track of |
| expressions present in the set. |
| |
| The other sets are represented as doubly linked lists kept in topological |
| order, with an optional supporting bitmap of values present in the |
| set. The sets represent values, and the elements can be values or |
| expressions. The elements can appear in different sets, but each |
| element can only appear once in each set. |
| |
| Since each node in the set represents a value, we also want to be |
| able to map expression, set pairs to something that tells us |
| whether the value is present is a set. We use a per-set bitmap for |
| that. The value handles also point to a linked list of the |
| expressions they represent via a tree annotation. This is mainly |
| useful only for debugging, since we don't do identity lookups. */ |
| |
| |
| /* A value set element. Basically a single linked list of |
| expressions/values. */ |
| typedef struct value_set_node |
| { |
| /* An expression. */ |
| tree expr; |
| |
| /* A pointer to the next element of the value set. */ |
| struct value_set_node *next; |
| } *value_set_node_t; |
| |
| |
| /* A value set. This is a singly linked list of value_set_node |
| elements with a possible bitmap that tells us what values exist in |
| the set. This set must be kept in topologically sorted order. */ |
| typedef struct value_set |
| { |
| /* The head of the list. Used for iterating over the list in |
| order. */ |
| value_set_node_t head; |
| |
| /* The tail of the list. Used for tail insertions, which are |
| necessary to keep the set in topologically sorted order because |
| of how the set is built. */ |
| value_set_node_t tail; |
| |
| /* The length of the list. */ |
| size_t length; |
| |
| /* True if the set is indexed, which means it contains a backing |
| bitmap for quick determination of whether certain values exist in the |
| set. */ |
| bool indexed; |
| |
| /* The bitmap of values that exist in the set. May be NULL in an |
| empty or non-indexed set. */ |
| bitmap values; |
| |
| } *value_set_t; |
| |
| |
| /* An unordered bitmap set. One bitmap tracks values, the other, |
| expressions. */ |
| typedef struct bitmap_set |
| { |
| bitmap expressions; |
| bitmap values; |
| } *bitmap_set_t; |
| |
| /* Sets that we need to keep track of. */ |
| typedef struct bb_value_sets |
| { |
| /* The EXP_GEN set, which represents expressions/values generated in |
| a basic block. */ |
| value_set_t exp_gen; |
| |
| /* The PHI_GEN set, which represents PHI results generated in a |
| basic block. */ |
| bitmap_set_t phi_gen; |
| |
| /* The TMP_GEN set, which represents results/temporaries generated |
| in a basic block. IE the LHS of an expression. */ |
| bitmap_set_t tmp_gen; |
| |
| /* The AVAIL_OUT set, which represents which values are available in |
| a given basic block. */ |
| bitmap_set_t avail_out; |
| |
| /* The ANTIC_IN set, which represents which values are anticiptable |
| in a given basic block. */ |
| value_set_t antic_in; |
| |
| /* The NEW_SETS set, which is used during insertion to augment the |
| AVAIL_OUT set of blocks with the new insertions performed during |
| the current iteration. */ |
| bitmap_set_t new_sets; |
| } *bb_value_sets_t; |
| |
| #define EXP_GEN(BB) ((bb_value_sets_t) ((BB)->aux))->exp_gen |
| #define PHI_GEN(BB) ((bb_value_sets_t) ((BB)->aux))->phi_gen |
| #define TMP_GEN(BB) ((bb_value_sets_t) ((BB)->aux))->tmp_gen |
| #define AVAIL_OUT(BB) ((bb_value_sets_t) ((BB)->aux))->avail_out |
| #define ANTIC_IN(BB) ((bb_value_sets_t) ((BB)->aux))->antic_in |
| #define NEW_SETS(BB) ((bb_value_sets_t) ((BB)->aux))->new_sets |
| |
| /* This structure is used to keep track of statistics on what |
| optimization PRE was able to perform. */ |
| static struct |
| { |
| /* The number of RHS computations eliminated by PRE. */ |
| int eliminations; |
| |
| /* The number of new expressions/temporaries generated by PRE. */ |
| int insertions; |
| |
| /* The number of new PHI nodes added by PRE. */ |
| int phis; |
| |
| /* The number of values found constant. */ |
| int constified; |
| |
| } pre_stats; |
| |
| |
| static tree bitmap_find_leader (bitmap_set_t, tree); |
| static tree find_leader (value_set_t, tree); |
| static void value_insert_into_set (value_set_t, tree); |
| static void bitmap_value_insert_into_set (bitmap_set_t, tree); |
| static void bitmap_value_replace_in_set (bitmap_set_t, tree); |
| static void insert_into_set (value_set_t, tree); |
| static void bitmap_set_copy (bitmap_set_t, bitmap_set_t); |
| static bool bitmap_set_contains_value (bitmap_set_t, tree); |
| static bitmap_set_t bitmap_set_new (void); |
| static value_set_t set_new (bool); |
| static bool is_undefined_value (tree); |
| static tree create_expression_by_pieces (basic_block, tree, tree); |
| |
| |
| /* We can add and remove elements and entries to and from sets |
| and hash tables, so we use alloc pools for them. */ |
| |
| static alloc_pool value_set_pool; |
| static alloc_pool bitmap_set_pool; |
| static alloc_pool value_set_node_pool; |
| static alloc_pool binary_node_pool; |
| static alloc_pool unary_node_pool; |
| static alloc_pool reference_node_pool; |
| static bitmap_obstack grand_bitmap_obstack; |
| |
| /* Set of blocks with statements that have had its EH information |
| cleaned up. */ |
| static bitmap need_eh_cleanup; |
| |
| /* The phi_translate_table caches phi translations for a given |
| expression and predecessor. */ |
| |
| static htab_t phi_translate_table; |
| |
| /* A three tuple {e, pred, v} used to cache phi translations in the |
| phi_translate_table. */ |
| |
| typedef struct expr_pred_trans_d |
| { |
| /* The expression. */ |
| tree e; |
| |
| /* The predecessor block along which we translated the expression. */ |
| basic_block pred; |
| |
| /* The value that resulted from the translation. */ |
| tree v; |
| |
| /* The hashcode for the expression, pred pair. This is cached for |
| speed reasons. */ |
| hashval_t hashcode; |
| } *expr_pred_trans_t; |
| |
| /* Return the hash value for a phi translation table entry. */ |
| |
| static hashval_t |
| expr_pred_trans_hash (const void *p) |
| { |
| const expr_pred_trans_t ve = (expr_pred_trans_t) p; |
| return ve->hashcode; |
| } |
| |
| /* Return true if two phi translation table entries are the same. |
| P1 and P2 should point to the expr_pred_trans_t's to be compared.*/ |
| |
| static int |
| expr_pred_trans_eq (const void *p1, const void *p2) |
| { |
| const expr_pred_trans_t ve1 = (expr_pred_trans_t) p1; |
| const expr_pred_trans_t ve2 = (expr_pred_trans_t) p2; |
| basic_block b1 = ve1->pred; |
| basic_block b2 = ve2->pred; |
| |
| |
| /* If they are not translations for the same basic block, they can't |
| be equal. */ |
| if (b1 != b2) |
| return false; |
| |
| /* If they are for the same basic block, determine if the |
| expressions are equal. */ |
| if (expressions_equal_p (ve1->e, ve2->e)) |
| return true; |
| |
| return false; |
| } |
| |
| /* Search in the phi translation table for the translation of |
| expression E in basic block PRED. Return the translated value, if |
| found, NULL otherwise. */ |
| |
| static inline tree |
| phi_trans_lookup (tree e, basic_block pred) |
| { |
| void **slot; |
| struct expr_pred_trans_d ept; |
| ept.e = e; |
| ept.pred = pred; |
| ept.hashcode = vn_compute (e, (unsigned long) pred, NULL); |
| slot = htab_find_slot_with_hash (phi_translate_table, &ept, ept.hashcode, |
| NO_INSERT); |
| if (!slot) |
| return NULL; |
| else |
| return ((expr_pred_trans_t) *slot)->v; |
| } |
| |
| |
| /* Add the tuple mapping from {expression E, basic block PRED} to |
| value V, to the phi translation table. */ |
| |
| static inline void |
| phi_trans_add (tree e, tree v, basic_block pred) |
| { |
| void **slot; |
| expr_pred_trans_t new_pair = xmalloc (sizeof (*new_pair)); |
| new_pair->e = e; |
| new_pair->pred = pred; |
| new_pair->v = v; |
| new_pair->hashcode = vn_compute (e, (unsigned long) pred, NULL); |
| slot = htab_find_slot_with_hash (phi_translate_table, new_pair, |
| new_pair->hashcode, INSERT); |
| if (*slot) |
| free (*slot); |
| *slot = (void *) new_pair; |
| } |
| |
| |
| /* Add expression E to the expression set of value V. */ |
| |
| void |
| add_to_value (tree v, tree e) |
| { |
| /* Constants have no expression sets. */ |
| if (is_gimple_min_invariant (v)) |
| return; |
| |
| if (VALUE_HANDLE_EXPR_SET (v) == NULL) |
| VALUE_HANDLE_EXPR_SET (v) = set_new (false); |
| |
| insert_into_set (VALUE_HANDLE_EXPR_SET (v), e); |
| } |
| |
| |
| /* Return true if value V exists in the bitmap for SET. */ |
| |
| static inline bool |
| value_exists_in_set_bitmap (value_set_t set, tree v) |
| { |
| if (!set->values) |
| return false; |
| |
| return bitmap_bit_p (set->values, VALUE_HANDLE_ID (v)); |
| } |
| |
| |
| /* Remove value V from the bitmap for SET. */ |
| |
| static void |
| value_remove_from_set_bitmap (value_set_t set, tree v) |
| { |
| gcc_assert (set->indexed); |
| |
| if (!set->values) |
| return; |
| |
| bitmap_clear_bit (set->values, VALUE_HANDLE_ID (v)); |
| } |
| |
| |
| /* Insert the value number V into the bitmap of values existing in |
| SET. */ |
| |
| static inline void |
| value_insert_into_set_bitmap (value_set_t set, tree v) |
| { |
| gcc_assert (set->indexed); |
| |
| if (set->values == NULL) |
| set->values = BITMAP_ALLOC (&grand_bitmap_obstack); |
| |
| bitmap_set_bit (set->values, VALUE_HANDLE_ID (v)); |
| } |
| |
| |
| /* Create a new bitmap set and return it. */ |
| |
| static bitmap_set_t |
| bitmap_set_new (void) |
| { |
| bitmap_set_t ret = pool_alloc (bitmap_set_pool); |
| ret->expressions = BITMAP_ALLOC (&grand_bitmap_obstack); |
| ret->values = BITMAP_ALLOC (&grand_bitmap_obstack); |
| return ret; |
| } |
| |
| /* Create a new set. */ |
| |
| static value_set_t |
| set_new (bool indexed) |
| { |
| value_set_t ret; |
| ret = pool_alloc (value_set_pool); |
| ret->head = ret->tail = NULL; |
| ret->length = 0; |
| ret->indexed = indexed; |
| ret->values = NULL; |
| return ret; |
| } |
| |
| /* Insert an expression EXPR into a bitmapped set. */ |
| |
| static void |
| bitmap_insert_into_set (bitmap_set_t set, tree expr) |
| { |
| tree val; |
| /* XXX: For now, we only let SSA_NAMES into the bitmap sets. */ |
| gcc_assert (TREE_CODE (expr) == SSA_NAME); |
| val = get_value_handle (expr); |
| |
| gcc_assert (val); |
| if (!is_gimple_min_invariant (val)) |
| { |
| bitmap_set_bit (set->values, VALUE_HANDLE_ID (val)); |
| bitmap_set_bit (set->expressions, SSA_NAME_VERSION (expr)); |
| } |
| } |
| |
| /* Insert EXPR into SET. */ |
| |
| static void |
| insert_into_set (value_set_t set, tree expr) |
| { |
| value_set_node_t newnode = pool_alloc (value_set_node_pool); |
| tree val = get_value_handle (expr); |
| gcc_assert (val); |
| |
| if (is_gimple_min_invariant (val)) |
| return; |
| |
| /* For indexed sets, insert the value into the set value bitmap. |
| For all sets, add it to the linked list and increment the list |
| length. */ |
| if (set->indexed) |
| value_insert_into_set_bitmap (set, val); |
| |
| newnode->next = NULL; |
| newnode->expr = expr; |
| set->length ++; |
| if (set->head == NULL) |
| { |
| set->head = set->tail = newnode; |
| } |
| else |
| { |
| set->tail->next = newnode; |
| set->tail = newnode; |
| } |
| } |
| |
| /* Copy a bitmapped set ORIG, into bitmapped set DEST. */ |
| |
| static void |
| bitmap_set_copy (bitmap_set_t dest, bitmap_set_t orig) |
| { |
| bitmap_copy (dest->expressions, orig->expressions); |
| bitmap_copy (dest->values, orig->values); |
| } |
| |
| /* Copy the set ORIG to the set DEST. */ |
| |
| static void |
| set_copy (value_set_t dest, value_set_t orig) |
| { |
| value_set_node_t node; |
| |
| if (!orig || !orig->head) |
| return; |
| |
| for (node = orig->head; |
| node; |
| node = node->next) |
| { |
| insert_into_set (dest, node->expr); |
| } |
| } |
| |
| /* Remove EXPR from SET. */ |
| |
| static void |
| set_remove (value_set_t set, tree expr) |
| { |
| value_set_node_t node, prev; |
| |
| /* Remove the value of EXPR from the bitmap, decrement the set |
| length, and remove it from the actual double linked list. */ |
| value_remove_from_set_bitmap (set, get_value_handle (expr)); |
| set->length--; |
| prev = NULL; |
| for (node = set->head; |
| node != NULL; |
| prev = node, node = node->next) |
| { |
| if (node->expr == expr) |
| { |
| if (prev == NULL) |
| set->head = node->next; |
| else |
| prev->next= node->next; |
| |
| if (node == set->tail) |
| set->tail = prev; |
| pool_free (value_set_node_pool, node); |
| return; |
| } |
| } |
| } |
| |
| /* Return true if SET contains the value VAL. */ |
| |
| static bool |
| set_contains_value (value_set_t set, tree val) |
| { |
| /* All constants are in every set. */ |
| if (is_gimple_min_invariant (val)) |
| return true; |
| |
| if (set->length == 0) |
| return false; |
| |
| return value_exists_in_set_bitmap (set, val); |
| } |
| |
| /* Return true if bitmapped set SET contains the expression EXPR. */ |
| static bool |
| bitmap_set_contains (bitmap_set_t set, tree expr) |
| { |
| /* All constants are in every set. */ |
| if (is_gimple_min_invariant (get_value_handle (expr))) |
| return true; |
| |
| /* XXX: Bitmapped sets only contain SSA_NAME's for now. */ |
| if (TREE_CODE (expr) != SSA_NAME) |
| return false; |
| return bitmap_bit_p (set->expressions, SSA_NAME_VERSION (expr)); |
| } |
| |
| |
| /* Return true if bitmapped set SET contains the value VAL. */ |
| |
| static bool |
| bitmap_set_contains_value (bitmap_set_t set, tree val) |
| { |
| if (is_gimple_min_invariant (val)) |
| return true; |
| return bitmap_bit_p (set->values, VALUE_HANDLE_ID (val)); |
| } |
| |
| /* Replace an instance of value LOOKFOR with expression EXPR in SET. */ |
| |
| static void |
| bitmap_set_replace_value (bitmap_set_t set, tree lookfor, tree expr) |
| { |
| value_set_t exprset; |
| value_set_node_t node; |
| if (is_gimple_min_invariant (lookfor)) |
| return; |
| if (!bitmap_set_contains_value (set, lookfor)) |
| return; |
| |
| /* The number of expressions having a given value is usually |
| significantly less than the total number of expressions in SET. |
| Thus, rather than check, for each expression in SET, whether it |
| has the value LOOKFOR, we walk the reverse mapping that tells us |
| what expressions have a given value, and see if any of those |
| expressions are in our set. For large testcases, this is about |
| 5-10x faster than walking the bitmap. If this is somehow a |
| significant lose for some cases, we can choose which set to walk |
| based on the set size. */ |
| exprset = VALUE_HANDLE_EXPR_SET (lookfor); |
| for (node = exprset->head; node; node = node->next) |
| { |
| if (TREE_CODE (node->expr) == SSA_NAME) |
| { |
| if (bitmap_bit_p (set->expressions, SSA_NAME_VERSION (node->expr))) |
| { |
| bitmap_clear_bit (set->expressions, SSA_NAME_VERSION (node->expr)); |
| bitmap_set_bit (set->expressions, SSA_NAME_VERSION (expr)); |
| return; |
| } |
| } |
| } |
| } |
| |
| /* Subtract bitmapped set B from value set A, and return the new set. */ |
| |
| static value_set_t |
| bitmap_set_subtract_from_value_set (value_set_t a, bitmap_set_t b, |
| bool indexed) |
| { |
| value_set_t ret = set_new (indexed); |
| value_set_node_t node; |
| for (node = a->head; |
| node; |
| node = node->next) |
| { |
| if (!bitmap_set_contains (b, node->expr)) |
| insert_into_set (ret, node->expr); |
| } |
| return ret; |
| } |
| |
| /* Return true if two sets are equal. */ |
| |
| static bool |
| set_equal (value_set_t a, value_set_t b) |
| { |
| value_set_node_t node; |
| |
| if (a->length != b->length) |
| return false; |
| for (node = a->head; |
| node; |
| node = node->next) |
| { |
| if (!set_contains_value (b, get_value_handle (node->expr))) |
| return false; |
| } |
| return true; |
| } |
| |
| /* Replace an instance of EXPR's VALUE with EXPR in SET if it exists, |
| and add it otherwise. */ |
| |
| static void |
| bitmap_value_replace_in_set (bitmap_set_t set, tree expr) |
| { |
| tree val = get_value_handle (expr); |
| if (bitmap_set_contains_value (set, val)) |
| bitmap_set_replace_value (set, val, expr); |
| else |
| bitmap_insert_into_set (set, expr); |
| } |
| |
| /* Insert EXPR into SET if EXPR's value is not already present in |
| SET. */ |
| |
| static void |
| bitmap_value_insert_into_set (bitmap_set_t set, tree expr) |
| { |
| tree val = get_value_handle (expr); |
| |
| if (is_gimple_min_invariant (val)) |
| return; |
| |
| if (!bitmap_set_contains_value (set, val)) |
| bitmap_insert_into_set (set, expr); |
| } |
| |
| /* Insert the value for EXPR into SET, if it doesn't exist already. */ |
| |
| static void |
| value_insert_into_set (value_set_t set, tree expr) |
| { |
| tree val = get_value_handle (expr); |
| |
| /* Constant and invariant values exist everywhere, and thus, |
| actually keeping them in the sets is pointless. */ |
| if (is_gimple_min_invariant (val)) |
| return; |
| |
| if (!set_contains_value (set, val)) |
| insert_into_set (set, expr); |
| } |
| |
| |
| /* Print out SET to OUTFILE. */ |
| |
| static void |
| bitmap_print_value_set (FILE *outfile, bitmap_set_t set, |
| const char *setname, int blockindex) |
| { |
| fprintf (outfile, "%s[%d] := { ", setname, blockindex); |
| if (set) |
| { |
| bool first = true; |
| unsigned i; |
| bitmap_iterator bi; |
| |
| EXECUTE_IF_SET_IN_BITMAP (set->expressions, 0, i, bi) |
| { |
| if (!first) |
| fprintf (outfile, ", "); |
| first = false; |
| print_generic_expr (outfile, ssa_name (i), 0); |
| |
| fprintf (outfile, " ("); |
| print_generic_expr (outfile, get_value_handle (ssa_name (i)), 0); |
| fprintf (outfile, ") "); |
| } |
| } |
| fprintf (outfile, " }\n"); |
| } |
| /* Print out the value_set SET to OUTFILE. */ |
| |
| static void |
| print_value_set (FILE *outfile, value_set_t set, |
| const char *setname, int blockindex) |
| { |
| value_set_node_t node; |
| fprintf (outfile, "%s[%d] := { ", setname, blockindex); |
| if (set) |
| { |
| for (node = set->head; |
| node; |
| node = node->next) |
| { |
| print_generic_expr (outfile, node->expr, 0); |
| |
| fprintf (outfile, " ("); |
| print_generic_expr (outfile, get_value_handle (node->expr), 0); |
| fprintf (outfile, ") "); |
| |
| if (node->next) |
| fprintf (outfile, ", "); |
| } |
| } |
| |
| fprintf (outfile, " }\n"); |
| } |
| |
| /* Print out the expressions that have VAL to OUTFILE. */ |
| |
| void |
| print_value_expressions (FILE *outfile, tree val) |
| { |
| if (VALUE_HANDLE_EXPR_SET (val)) |
| { |
| char s[10]; |
| sprintf (s, "VH.%04d", VALUE_HANDLE_ID (val)); |
| print_value_set (outfile, VALUE_HANDLE_EXPR_SET (val), s, 0); |
| } |
| } |
| |
| |
| void |
| debug_value_expressions (tree val) |
| { |
| print_value_expressions (stderr, val); |
| } |
| |
| |
| void debug_value_set (value_set_t, const char *, int); |
| |
| void |
| debug_value_set (value_set_t set, const char *setname, int blockindex) |
| { |
| print_value_set (stderr, set, setname, blockindex); |
| } |
| |
| /* Translate EXPR using phis in PHIBLOCK, so that it has the values of |
| the phis in PRED. Return NULL if we can't find a leader for each |
| part of the translated expression. */ |
| |
| static tree |
| phi_translate (tree expr, value_set_t set, basic_block pred, |
| basic_block phiblock) |
| { |
| tree phitrans = NULL; |
| tree oldexpr = expr; |
| |
| if (expr == NULL) |
| return NULL; |
| |
| if (is_gimple_min_invariant (expr)) |
| return expr; |
| |
| /* Phi translations of a given expression don't change. */ |
| phitrans = phi_trans_lookup (expr, pred); |
| if (phitrans) |
| return phitrans; |
| |
| switch (TREE_CODE_CLASS (TREE_CODE (expr))) |
| { |
| case tcc_reference: |
| /* XXX: Until we have PRE of loads working, none will be ANTIC. */ |
| return NULL; |
| |
| case tcc_binary: |
| { |
| tree oldop1 = TREE_OPERAND (expr, 0); |
| tree oldop2 = TREE_OPERAND (expr, 1); |
| tree newop1; |
| tree newop2; |
| tree newexpr; |
| |
| newop1 = phi_translate (find_leader (set, oldop1), |
| set, pred, phiblock); |
| if (newop1 == NULL) |
| return NULL; |
| newop2 = phi_translate (find_leader (set, oldop2), |
| set, pred, phiblock); |
| if (newop2 == NULL) |
| return NULL; |
| if (newop1 != oldop1 || newop2 != oldop2) |
| { |
| newexpr = pool_alloc (binary_node_pool); |
| memcpy (newexpr, expr, tree_size (expr)); |
| create_tree_ann (newexpr); |
| TREE_OPERAND (newexpr, 0) = newop1 == oldop1 ? oldop1 : get_value_handle (newop1); |
| TREE_OPERAND (newexpr, 1) = newop2 == oldop2 ? oldop2 : get_value_handle (newop2); |
| vn_lookup_or_add (newexpr, NULL); |
| expr = newexpr; |
| phi_trans_add (oldexpr, newexpr, pred); |
| } |
| } |
| return expr; |
| |
| case tcc_unary: |
| { |
| tree oldop1 = TREE_OPERAND (expr, 0); |
| tree newop1; |
| tree newexpr; |
| |
| newop1 = phi_translate (find_leader (set, oldop1), |
| set, pred, phiblock); |
| if (newop1 == NULL) |
| return NULL; |
| if (newop1 != oldop1) |
| { |
| newexpr = pool_alloc (unary_node_pool); |
| memcpy (newexpr, expr, tree_size (expr)); |
| create_tree_ann (newexpr); |
| TREE_OPERAND (newexpr, 0) = get_value_handle (newop1); |
| vn_lookup_or_add (newexpr, NULL); |
| expr = newexpr; |
| phi_trans_add (oldexpr, newexpr, pred); |
| } |
| } |
| return expr; |
| |
| case tcc_exceptional: |
| { |
| tree phi = NULL; |
| edge e; |
| gcc_assert (TREE_CODE (expr) == SSA_NAME); |
| if (TREE_CODE (SSA_NAME_DEF_STMT (expr)) == PHI_NODE) |
| phi = SSA_NAME_DEF_STMT (expr); |
| else |
| return expr; |
| |
| e = find_edge (pred, bb_for_stmt (phi)); |
| if (e) |
| { |
| if (is_undefined_value (PHI_ARG_DEF (phi, e->dest_idx))) |
| return NULL; |
| vn_lookup_or_add (PHI_ARG_DEF (phi, e->dest_idx), NULL); |
| return PHI_ARG_DEF (phi, e->dest_idx); |
| } |
| } |
| return expr; |
| |
| default: |
| gcc_unreachable (); |
| } |
| } |
| |
| static void |
| phi_translate_set (value_set_t dest, value_set_t set, basic_block pred, |
| basic_block phiblock) |
| { |
| value_set_node_t node; |
| for (node = set->head; |
| node; |
| node = node->next) |
| { |
| tree translated; |
| translated = phi_translate (node->expr, set, pred, phiblock); |
| phi_trans_add (node->expr, translated, pred); |
| |
| if (translated != NULL) |
| value_insert_into_set (dest, translated); |
| } |
| } |
| |
| /* Find the leader for a value (i.e., the name representing that |
| value) in a given set, and return it. Return NULL if no leader is |
| found. */ |
| |
| static tree |
| bitmap_find_leader (bitmap_set_t set, tree val) |
| { |
| if (val == NULL) |
| return NULL; |
| |
| if (is_gimple_min_invariant (val)) |
| return val; |
| if (bitmap_set_contains_value (set, val)) |
| { |
| /* Rather than walk the entire bitmap of expressions, and see |
| whether any of them has the value we are looking for, we look |
| at the reverse mapping, which tells us the set of expressions |
| that have a given value (IE value->expressions with that |
| value) and see if any of those expressions are in our set. |
| The number of expressions per value is usually significantly |
| less than the number of expressions in the set. In fact, for |
| large testcases, doing it this way is roughly 5-10x faster |
| than walking the bitmap. |
| If this is somehow a significant lose for some cases, we can |
| choose which set to walk based on which set is smaller. */ |
| value_set_t exprset; |
| value_set_node_t node; |
| exprset = VALUE_HANDLE_EXPR_SET (val); |
| for (node = exprset->head; node; node = node->next) |
| { |
| if (TREE_CODE (node->expr) == SSA_NAME) |
| { |
| if (bitmap_bit_p (set->expressions, |
| SSA_NAME_VERSION (node->expr))) |
| return node->expr; |
| } |
| } |
| } |
| return NULL; |
| } |
| |
| |
| /* Find the leader for a value (i.e., the name representing that |
| value) in a given set, and return it. Return NULL if no leader is |
| found. */ |
| |
| static tree |
| find_leader (value_set_t set, tree val) |
| { |
| value_set_node_t node; |
| |
| if (val == NULL) |
| return NULL; |
| |
| /* Constants represent themselves. */ |
| if (is_gimple_min_invariant (val)) |
| return val; |
| |
| if (set->length == 0) |
| return NULL; |
| |
| if (value_exists_in_set_bitmap (set, val)) |
| { |
| for (node = set->head; |
| node; |
| node = node->next) |
| { |
| if (get_value_handle (node->expr) == val) |
| return node->expr; |
| } |
| } |
| |
| return NULL; |
| } |
| |
| /* Determine if the expression EXPR is valid in SET. This means that |
| we have a leader for each part of the expression (if it consists of |
| values), or the expression is an SSA_NAME. |
| |
| NB: We never should run into a case where we have SSA_NAME + |
| SSA_NAME or SSA_NAME + value. The sets valid_in_set is called on, |
| the ANTIC sets, will only ever have SSA_NAME's or binary value |
| expression (IE VALUE1 + VALUE2) */ |
| |
| static bool |
| valid_in_set (value_set_t set, tree expr) |
| { |
| switch (TREE_CODE_CLASS (TREE_CODE (expr))) |
| { |
| case tcc_binary: |
| { |
| tree op1 = TREE_OPERAND (expr, 0); |
| tree op2 = TREE_OPERAND (expr, 1); |
| return set_contains_value (set, op1) && set_contains_value (set, op2); |
| } |
| |
| case tcc_unary: |
| { |
| tree op1 = TREE_OPERAND (expr, 0); |
| return set_contains_value (set, op1); |
| } |
| |
| case tcc_reference: |
| /* XXX: Until PRE of loads works, no reference nodes are ANTIC. */ |
| return false; |
| |
| case tcc_exceptional: |
| gcc_assert (TREE_CODE (expr) == SSA_NAME); |
| return true; |
| |
| /* APPLE LOCAL begin mainline 4300156 */ |
| case tcc_declaration: |
| /* VAR_DECL and PARM_DECL are never anticipatable. */ |
| return false; |
| /* APPLE LOCAL end mainline 4300156 */ |
| |
| default: |
| /* No other cases should be encountered. */ |
| gcc_unreachable (); |
| } |
| } |
| |
| /* Clean the set of expressions that are no longer valid in SET. This |
| means expressions that are made up of values we have no leaders for |
| in SET. */ |
| |
| static void |
| clean (value_set_t set) |
| { |
| value_set_node_t node; |
| value_set_node_t next; |
| node = set->head; |
| while (node) |
| { |
| next = node->next; |
| if (!valid_in_set (set, node->expr)) |
| set_remove (set, node->expr); |
| node = next; |
| } |
| } |
| |
| DEF_VEC_MALLOC_P (basic_block); |
| sbitmap has_abnormal_preds; |
| |
| /* Compute the ANTIC set for BLOCK. |
| |
| If succs(BLOCK) > 1 then |
| ANTIC_OUT[BLOCK] = intersection of ANTIC_IN[b] for all succ(BLOCK) |
| else if succs(BLOCK) == 1 then |
| ANTIC_OUT[BLOCK] = phi_translate (ANTIC_IN[succ(BLOCK)]) |
| |
| ANTIC_IN[BLOCK] = clean(ANTIC_OUT[BLOCK] U EXP_GEN[BLOCK] - TMP_GEN[BLOCK]) |
| |
| XXX: It would be nice to either write a set_clear, and use it for |
| ANTIC_OUT, or to mark the antic_out set as deleted at the end |
| of this routine, so that the pool can hand the same memory back out |
| again for the next ANTIC_OUT. */ |
| |
| static bool |
| compute_antic_aux (basic_block block, bool block_has_abnormal_pred_edge) |
| { |
| basic_block son; |
| bool changed = false; |
| value_set_t S, old, ANTIC_OUT; |
| value_set_node_t node; |
| |
| ANTIC_OUT = S = NULL; |
| |
| /* If any edges from predecessors are abnormal, antic_in is empty, |
| so do nothing. */ |
| if (block_has_abnormal_pred_edge) |
| goto maybe_dump_sets; |
| |
| old = set_new (false); |
| set_copy (old, ANTIC_IN (block)); |
| ANTIC_OUT = set_new (true); |
| |
| /* If the block has no successors, ANTIC_OUT is empty. */ |
| if (EDGE_COUNT (block->succs) == 0) |
| ; |
| /* If we have one successor, we could have some phi nodes to |
| translate through. */ |
| else if (EDGE_COUNT (block->succs) == 1) |
| { |
| phi_translate_set (ANTIC_OUT, ANTIC_IN(EDGE_SUCC (block, 0)->dest), |
| block, EDGE_SUCC (block, 0)->dest); |
| } |
| /* If we have multiple successors, we take the intersection of all of |
| them. */ |
| else |
| { |
| VEC (basic_block) * worklist; |
| edge e; |
| size_t i; |
| basic_block bprime, first; |
| edge_iterator ei; |
| |
| worklist = VEC_alloc (basic_block, 2); |
| FOR_EACH_EDGE (e, ei, block->succs) |
| VEC_safe_push (basic_block, worklist, e->dest); |
| first = VEC_index (basic_block, worklist, 0); |
| set_copy (ANTIC_OUT, ANTIC_IN (first)); |
| |
| for (i = 1; VEC_iterate (basic_block, worklist, i, bprime); i++) |
| { |
| node = ANTIC_OUT->head; |
| while (node) |
| { |
| tree val; |
| value_set_node_t next = node->next; |
| val = get_value_handle (node->expr); |
| if (!set_contains_value (ANTIC_IN (bprime), val)) |
| set_remove (ANTIC_OUT, node->expr); |
| node = next; |
| } |
| } |
| VEC_free (basic_block, worklist); |
| } |
| |
| /* Generate ANTIC_OUT - TMP_GEN. */ |
| S = bitmap_set_subtract_from_value_set (ANTIC_OUT, TMP_GEN (block), false); |
| |
| /* Start ANTIC_IN with EXP_GEN - TMP_GEN */ |
| ANTIC_IN (block) = bitmap_set_subtract_from_value_set (EXP_GEN (block), |
| TMP_GEN (block), |
| true); |
| |
| /* Then union in the ANTIC_OUT - TMP_GEN values, |
| to get ANTIC_OUT U EXP_GEN - TMP_GEN */ |
| for (node = S->head; node; node = node->next) |
| value_insert_into_set (ANTIC_IN (block), node->expr); |
| |
| clean (ANTIC_IN (block)); |
| if (!set_equal (old, ANTIC_IN (block))) |
| changed = true; |
| |
| maybe_dump_sets: |
| if (dump_file && (dump_flags & TDF_DETAILS)) |
| { |
| if (ANTIC_OUT) |
| print_value_set (dump_file, ANTIC_OUT, "ANTIC_OUT", block->index); |
| print_value_set (dump_file, ANTIC_IN (block), "ANTIC_IN", block->index); |
| if (S) |
| print_value_set (dump_file, S, "S", block->index); |
| } |
| |
| for (son = first_dom_son (CDI_POST_DOMINATORS, block); |
| son; |
| son = next_dom_son (CDI_POST_DOMINATORS, son)) |
| { |
| changed |= compute_antic_aux (son, |
| TEST_BIT (has_abnormal_preds, son->index)); |
| } |
| return changed; |
| } |
| |
| /* Compute ANTIC sets. */ |
| |
| static void |
| compute_antic (void) |
| { |
| bool changed = true; |
| int num_iterations = 0; |
| basic_block block; |
| |
| /* If any predecessor edges are abnormal, we punt, so antic_in is empty. |
| We pre-build the map of blocks with incoming abnormal edges here. */ |
| has_abnormal_preds = sbitmap_alloc (last_basic_block); |
| sbitmap_zero (has_abnormal_preds); |
| FOR_EACH_BB (block) |
| { |
| edge_iterator ei; |
| edge e; |
| |
| FOR_EACH_EDGE (e, ei, block->preds) |
| if (e->flags & EDGE_ABNORMAL) |
| { |
| SET_BIT (has_abnormal_preds, block->index); |
| break; |
| } |
| |
| /* While we are here, give empty ANTIC_IN sets to each block. */ |
| ANTIC_IN (block) = set_new (true); |
| } |
| /* At the exit block we anticipate nothing. */ |
| ANTIC_IN (EXIT_BLOCK_PTR) = set_new (true); |
| |
| while (changed) |
| { |
| num_iterations++; |
| changed = false; |
| changed = compute_antic_aux (EXIT_BLOCK_PTR, false); |
| } |
| |
| sbitmap_free (has_abnormal_preds); |
| |
| if (dump_file && (dump_flags & TDF_STATS)) |
| fprintf (dump_file, "compute_antic required %d iterations\n", num_iterations); |
| } |
| |
| static VEC(tree_on_heap) *inserted_exprs; |
| /* Find a leader for an expression, or generate one using |
| create_expression_by_pieces if it's ANTIC but |
| complex. |
| BLOCK is the basic_block we are looking for leaders in. |
| EXPR is the expression to find a leader or generate for. |
| STMTS is the statement list to put the inserted expressions on. |
| Returns the SSA_NAME of the LHS of the generated expression or the |
| leader. */ |
| |
| static tree |
| find_or_generate_expression (basic_block block, tree expr, tree stmts) |
| { |
| tree genop = bitmap_find_leader (AVAIL_OUT (block), expr); |
| |
| /* If it's still NULL, see if it is a complex expression, and if |
| so, generate it recursively, otherwise, abort, because it's |
| not really . */ |
| if (genop == NULL) |
| { |
| genop = VALUE_HANDLE_EXPR_SET (expr)->head->expr; |
| gcc_assert (UNARY_CLASS_P (genop) |
| || BINARY_CLASS_P (genop) |
| || REFERENCE_CLASS_P (genop)); |
| genop = create_expression_by_pieces (block, genop, stmts); |
| } |
| return genop; |
| } |
| |
| #define NECESSARY(stmt) stmt->common.asm_written_flag |
| /* Create an expression in pieces, so that we can handle very complex |
| expressions that may be ANTIC, but not necessary GIMPLE. |
| BLOCK is the basic block the expression will be inserted into, |
| EXPR is the expression to insert (in value form) |
| STMTS is a statement list to append the necessary insertions into. |
| |
| This function will abort if we hit some value that shouldn't be |
| ANTIC but is (IE there is no leader for it, or its components). |
| This function may also generate expressions that are themselves |
| partially or fully redundant. Those that are will be either made |
| fully redundant during the next iteration of insert (for partially |
| redundant ones), or eliminated by eliminate (for fully redundant |
| ones). */ |
| |
| static tree |
| create_expression_by_pieces (basic_block block, tree expr, tree stmts) |
| { |
| tree name = NULL_TREE; |
| tree newexpr = NULL_TREE; |
| tree v; |
| |
| switch (TREE_CODE_CLASS (TREE_CODE (expr))) |
| { |
| case tcc_binary: |
| { |
| tree_stmt_iterator tsi; |
| tree forced_stmts; |
| tree genop1, genop2; |
| tree temp; |
| tree folded; |
| tree op1 = TREE_OPERAND (expr, 0); |
| tree op2 = TREE_OPERAND (expr, 1); |
| genop1 = find_or_generate_expression (block, op1, stmts); |
| genop2 = find_or_generate_expression (block, op2, stmts); |
| temp = create_tmp_var (TREE_TYPE (expr), "pretmp"); |
| add_referenced_tmp_var (temp); |
| |
| folded = fold (build (TREE_CODE (expr), TREE_TYPE (expr), |
| genop1, genop2)); |
| newexpr = force_gimple_operand (unshare_expr (folded), |
| &forced_stmts, false, NULL); |
| if (forced_stmts) |
| { |
| tsi = tsi_start (forced_stmts); |
| for (; !tsi_end_p (tsi); tsi_next (&tsi)) |
| { |
| tree stmt = tsi_stmt (tsi); |
| tree forcedname = TREE_OPERAND (stmt, 0); |
| tree forcedexpr = TREE_OPERAND (stmt, 1); |
| tree val = vn_lookup_or_add (forcedexpr, NULL); |
| |
| VEC_safe_push (tree_on_heap, inserted_exprs, stmt); |
| vn_add (forcedname, val, NULL); |
| bitmap_value_replace_in_set (NEW_SETS (block), forcedname); |
| bitmap_value_replace_in_set (AVAIL_OUT (block), forcedname); |
| } |
| |
| tsi = tsi_last (stmts); |
| tsi_link_after (&tsi, forced_stmts, TSI_CONTINUE_LINKING); |
| } |
| newexpr = build (MODIFY_EXPR, TREE_TYPE (expr), |
| temp, newexpr); |
| NECESSARY (newexpr) = 0; |
| name = make_ssa_name (temp, newexpr); |
| TREE_OPERAND (newexpr, 0) = name; |
| tsi = tsi_last (stmts); |
| tsi_link_after (&tsi, newexpr, TSI_CONTINUE_LINKING); |
| VEC_safe_push (tree_on_heap, inserted_exprs, newexpr); |
| pre_stats.insertions++; |
| break; |
| } |
| case tcc_unary: |
| { |
| tree_stmt_iterator tsi; |
| tree forced_stmts = NULL; |
| tree genop1; |
| tree temp; |
| tree folded; |
| tree op1 = TREE_OPERAND (expr, 0); |
| genop1 = find_or_generate_expression (block, op1, stmts); |
| temp = create_tmp_var (TREE_TYPE (expr), "pretmp"); |
| add_referenced_tmp_var (temp); |
| folded = fold (build (TREE_CODE (expr), TREE_TYPE (expr), |
| genop1)); |
| newexpr = force_gimple_operand (unshare_expr (folded), |
| &forced_stmts, false, NULL); |
| if (forced_stmts) |
| { |
| tsi = tsi_start (forced_stmts); |
| for (; !tsi_end_p (tsi); tsi_next (&tsi)) |
| { |
| tree stmt = tsi_stmt (tsi); |
| tree forcedname = TREE_OPERAND (stmt, 0); |
| tree forcedexpr = TREE_OPERAND (stmt, 1); |
| tree val = vn_lookup_or_add (forcedexpr, NULL); |
| |
| VEC_safe_push (tree_on_heap, inserted_exprs, stmt); |
| vn_add (forcedname, val, NULL); |
| bitmap_value_replace_in_set (NEW_SETS (block), forcedname); |
| bitmap_value_replace_in_set (AVAIL_OUT (block), forcedname); |
| } |
| tsi = tsi_last (stmts); |
| tsi_link_after (&tsi, forced_stmts, TSI_CONTINUE_LINKING); |
| } |
| newexpr = build (MODIFY_EXPR, TREE_TYPE (expr), |
| temp, newexpr); |
| name = make_ssa_name (temp, newexpr); |
| TREE_OPERAND (newexpr, 0) = name; |
| NECESSARY (newexpr) = 0; |
| tsi = tsi_last (stmts); |
| tsi_link_after (&tsi, newexpr, TSI_CONTINUE_LINKING); |
| VEC_safe_push (tree_on_heap, inserted_exprs, newexpr); |
| pre_stats.insertions++; |
| |
| break; |
| } |
| default: |
| gcc_unreachable (); |
| |
| } |
| v = get_value_handle (expr); |
| vn_add (name, v, NULL); |
| |
| /* The value may already exist in either NEW_SETS, or AVAIL_OUT, because |
| we are creating the expression by pieces, and this particular piece of |
| the expression may have been represented. There is no harm in replacing |
| here. */ |
| bitmap_value_replace_in_set (NEW_SETS (block), name); |
| bitmap_value_replace_in_set (AVAIL_OUT (block), name); |
| if (dump_file && (dump_flags & TDF_DETAILS)) |
| { |
| fprintf (dump_file, "Inserted "); |
| print_generic_expr (dump_file, newexpr, 0); |
| fprintf (dump_file, " in predecessor %d\n", block->index); |
| } |
| return name; |
| } |
| |
| /* Return the folded version of T if T, when folded, is a gimple |
| min_invariant. Otherwise, return T. */ |
| |
| static tree |
| fully_constant_expression (tree t) |
| { |
| tree folded; |
| folded = fold (t); |
| if (folded && is_gimple_min_invariant (folded)) |
| return folded; |
| return t; |
| } |
| |
| /* Insert the to-be-made-available values of NODE for each predecessor, stored |
| in AVAIL, into the predecessors of BLOCK, and merge the result with a phi |
| node, given the same value handle as NODE. The prefix of the phi node is |
| given with TMPNAME. Return true if we have inserted new stuff. */ |
| |
| static bool |
| insert_into_preds_of_block (basic_block block, value_set_node_t node, |
| tree *avail, const char *tmpname) |
| { |
| tree val = get_value_handle (node->expr); |
| edge pred; |
| bool insertions = false; |
| bool nophi = false; |
| basic_block bprime; |
| tree eprime; |
| edge_iterator ei; |
| tree type = TREE_TYPE (avail[EDGE_PRED (block, 0)->src->index]); |
| tree temp; |
| |
| if (dump_file && (dump_flags & TDF_DETAILS)) |
| { |
| fprintf (dump_file, "Found partial redundancy for expression "); |
| print_generic_expr (dump_file, node->expr, 0); |
| fprintf (dump_file, "\n"); |
| } |
| |
| /* Make sure we aren't creating an induction variable. */ |
| if (block->loop_depth > 0 && EDGE_COUNT (block->preds) == 2) |
| { |
| bool firstinsideloop = false; |
| bool secondinsideloop = false; |
| firstinsideloop = flow_bb_inside_loop_p (block->loop_father, |
| EDGE_PRED (block, 0)->src); |
| secondinsideloop = flow_bb_inside_loop_p (block->loop_father, |
| EDGE_PRED (block, 1)->src); |
| /* Induction variables only have one edge inside the loop. */ |
| if (firstinsideloop ^ secondinsideloop) |
| { |
| if (dump_file && (dump_flags & TDF_DETAILS)) |
| fprintf (dump_file, "Skipping insertion of phi for partial redundancy: Looks like an induction variable\n"); |
| nophi = true; |
| } |
| } |
| |
| |
| /* Make the necessary insertions. */ |
| FOR_EACH_EDGE (pred, ei, block->preds) |
| { |
| tree stmts = alloc_stmt_list (); |
| tree builtexpr; |
| bprime = pred->src; |
| eprime = avail[bprime->index]; |
| if (BINARY_CLASS_P (eprime) |
| || UNARY_CLASS_P (eprime)) |
| { |
| builtexpr = create_expression_by_pieces (bprime, |
| eprime, |
| stmts); |
| bsi_insert_on_edge (pred, stmts); |
| avail[bprime->index] = builtexpr; |
| insertions = true; |
| } |
| } |
| /* If we didn't want a phi node, and we made insertions, we still have |
| inserted new stuff, and thus return true. If we didn't want a phi node, |
| and didn't make insertions, we haven't added anything new, so return |
| false. */ |
| if (nophi && insertions) |
| return true; |
| else if (nophi && !insertions) |
| return false; |
| |
| /* Now build a phi for the new variable. */ |
| temp = create_tmp_var (type, tmpname); |
| add_referenced_tmp_var (temp); |
| temp = create_phi_node (temp, block); |
| NECESSARY (temp) = 0; |
| VEC_safe_push (tree_on_heap, inserted_exprs, temp); |
| FOR_EACH_EDGE (pred, ei, block->preds) |
| add_phi_arg (temp, avail[pred->src->index], pred); |
| |
| vn_add (PHI_RESULT (temp), val, NULL); |
| |
| /* The value should *not* exist in PHI_GEN, or else we wouldn't be doing |
| this insertion, since we test for the existence of this value in PHI_GEN |
| before proceeding with the partial redundancy checks in insert_aux. |
| |
| The value may exist in AVAIL_OUT, in particular, it could be represented |
| by the expression we are trying to eliminate, in which case we want the |
| replacement to occur. If it's not existing in AVAIL_OUT, we want it |
| inserted there. |
| |
| Similarly, to the PHI_GEN case, the value should not exist in NEW_SETS of |
| this block, because if it did, it would have existed in our dominator's |
| AVAIL_OUT, and would have been skipped due to the full redundancy check. |
| */ |
| |
| bitmap_insert_into_set (PHI_GEN (block), |
| PHI_RESULT (temp)); |
| bitmap_value_replace_in_set (AVAIL_OUT (block), |
| PHI_RESULT (temp)); |
| bitmap_insert_into_set (NEW_SETS (block), |
| PHI_RESULT (temp)); |
| |
| if (dump_file && (dump_flags & TDF_DETAILS)) |
| { |
| fprintf (dump_file, "Created phi "); |
| print_generic_expr (dump_file, temp, 0); |
| fprintf (dump_file, " in block %d\n", block->index); |
| } |
| pre_stats.phis++; |
| return true; |
| } |
| |
| |
| |
| /* Perform insertion of partially redundant values. |
| For BLOCK, do the following: |
| 1. Propagate the NEW_SETS of the dominator into the current block. |
| If the block has multiple predecessors, |
| 2a. Iterate over the ANTIC expressions for the block to see if |
| any of them are partially redundant. |
| 2b. If so, insert them into the necessary predecessors to make |
| the expression fully redundant. |
| 2c. Insert a new PHI merging the values of the predecessors. |
| 2d. Insert the new PHI, and the new expressions, into the |
| NEW_SETS set. |
| 3. Recursively call ourselves on the dominator children of BLOCK. |
| |
| */ |
| |
| static bool |
| insert_aux (basic_block block) |
| { |
| basic_block son; |
| bool new_stuff = false; |
| |
| if (block) |
| { |
| basic_block dom; |
| dom = get_immediate_dominator (CDI_DOMINATORS, block); |
| if (dom) |
| { |
| unsigned i; |
| bitmap_iterator bi; |
| bitmap_set_t newset = NEW_SETS (dom); |
| if (newset) |
| { |
| /* Note that we need to value_replace both NEW_SETS, and |
| AVAIL_OUT. For both the case of NEW_SETS, the value may be |
| represented by some non-simple expression here that we want |
| to replace it with. */ |
| EXECUTE_IF_SET_IN_BITMAP (newset->expressions, 0, i, bi) |
| { |
| bitmap_value_replace_in_set (NEW_SETS (block), ssa_name (i)); |
| bitmap_value_replace_in_set (AVAIL_OUT (block), ssa_name (i)); |
| } |
| } |
| if (EDGE_COUNT (block->preds) > 1) |
| { |
| value_set_node_t node; |
| for (node = ANTIC_IN (block)->head; |
| node; |
| node = node->next) |
| { |
| if (BINARY_CLASS_P (node->expr) |
| || UNARY_CLASS_P (node->expr)) |
| { |
| tree *avail; |
| tree val; |
| bool by_some = false; |
| bool cant_insert = false; |
| bool all_same = true; |
| tree first_s = NULL; |
| edge pred; |
| basic_block bprime; |
| tree eprime = NULL_TREE; |
| edge_iterator ei; |
| |
| val = get_value_handle (node->expr); |
| if (bitmap_set_contains_value (PHI_GEN (block), val)) |
| continue; |
| if (bitmap_set_contains_value (AVAIL_OUT (dom), val)) |
| { |
| if (dump_file && (dump_flags & TDF_DETAILS)) |
| fprintf (dump_file, "Found fully redundant value\n"); |
| continue; |
| } |
| |
| avail = xcalloc (last_basic_block, sizeof (tree)); |
| FOR_EACH_EDGE (pred, ei, block->preds) |
| { |
| tree vprime; |
| tree edoubleprime; |
| |
| /* This can happen in the very weird case |
| that our fake infinite loop edges have caused a |
| critical edge to appear. */ |
| if (EDGE_CRITICAL_P (pred)) |
| { |
| cant_insert = true; |
| break; |
| } |
| bprime = pred->src; |
| eprime = phi_translate (node->expr, |
| ANTIC_IN (block), |
| bprime, block); |
| |
| /* eprime will generally only be NULL if the |
| value of the expression, translated |
| through the PHI for this predecessor, is |
| undefined. If that is the case, we can't |
| make the expression fully redundant, |
| because its value is undefined along a |
| predecessor path. We can thus break out |
| early because it doesn't matter what the |
| rest of the results are. */ |
| if (eprime == NULL) |
| { |
| cant_insert = true; |
| break; |
| } |
| |
| eprime = fully_constant_expression (eprime); |
| vprime = get_value_handle (eprime); |
| gcc_assert (vprime); |
| edoubleprime = bitmap_find_leader (AVAIL_OUT (bprime), |
| vprime); |
| if (edoubleprime == NULL) |
| { |
| avail[bprime->index] = eprime; |
| all_same = false; |
| } |
| else |
| { |
| avail[bprime->index] = edoubleprime; |
| by_some = true; |
| if (first_s == NULL) |
| first_s = edoubleprime; |
| else if (!operand_equal_p (first_s, edoubleprime, |
| 0)) |
| all_same = false; |
| } |
| } |
| /* If we can insert it, it's not the same value |
| already existing along every predecessor, and |
| it's defined by some predecessor, it is |
| partially redundant. */ |
| if (!cant_insert && !all_same && by_some) |
| { |
| if (insert_into_preds_of_block (block, node, avail, |
| "prephitmp")) |
| new_stuff = true; |
| } |
| /* If all edges produce the same value and that value is |
| an invariant, then the PHI has the same value on all |
| edges. Note this. */ |
| else if (!cant_insert && all_same && eprime |
| && is_gimple_min_invariant (eprime) |
| && !is_gimple_min_invariant (val)) |
| { |
| value_set_t exprset = VALUE_HANDLE_EXPR_SET (val); |
| value_set_node_t node; |
| for (node = exprset->head; node; node = node->next) |
| { |
| if (TREE_CODE (node->expr) == SSA_NAME) |
| { |
| vn_add (node->expr, eprime, NULL); |
| pre_stats.constified++; |
| } |
| } |
| } |
| free (avail); |
| } |
| } |
| } |
| } |
| } |
| for (son = first_dom_son (CDI_DOMINATORS, block); |
| son; |
| son = next_dom_son (CDI_DOMINATORS, son)) |
| { |
| new_stuff |= insert_aux (son); |
| } |
| |
| return new_stuff; |
| } |
| |
| /* Perform insertion of partially redundant values. */ |
| |
| static void |
| insert (void) |
| { |
| bool new_stuff = true; |
| basic_block bb; |
| int num_iterations = 0; |
| |
| FOR_ALL_BB (bb) |
| NEW_SETS (bb) = bitmap_set_new (); |
| |
| while (new_stuff) |
| { |
| num_iterations++; |
| new_stuff = false; |
| new_stuff = insert_aux (ENTRY_BLOCK_PTR); |
| } |
| if (num_iterations > 2 && dump_file && (dump_flags & TDF_STATS)) |
| fprintf (dump_file, "insert required %d iterations\n", num_iterations); |
| } |
| |
| |
| /* Return true if VAR is an SSA variable with no defining statement in |
| this procedure, *AND* isn't a live-on-entry parameter. */ |
| |
| static bool |
| is_undefined_value (tree expr) |
| { |
| return (TREE_CODE (expr) == SSA_NAME |
| && IS_EMPTY_STMT (SSA_NAME_DEF_STMT (expr)) |
| /* PARM_DECLs and hard registers are always defined. */ |
| && TREE_CODE (SSA_NAME_VAR (expr)) != PARM_DECL); |
| } |
| |
| |
| /* Given an SSA variable VAR and an expression EXPR, compute the value |
| number for EXPR and create a value handle (VAL) for it. If VAR and |
| EXPR are not the same, associate VAL with VAR. Finally, add VAR to |
| S1 and its value handle to S2. |
| |
| VUSES represent the virtual use operands associated with EXPR (if |
| any). They are used when computing the hash value for EXPR. */ |
| |
| static inline void |
| add_to_sets (tree var, tree expr, vuse_optype vuses, bitmap_set_t s1, |
| bitmap_set_t s2) |
| { |
| tree val = vn_lookup_or_add (expr, vuses); |
| |
| /* VAR and EXPR may be the same when processing statements for which |
| we are not computing value numbers (e.g., non-assignments, or |
| statements that make aliased stores). In those cases, we are |
| only interested in making VAR available as its own value. */ |
| if (var != expr) |
| vn_add (var, val, NULL); |
| |
| if (s1) |
| bitmap_insert_into_set (s1, var); |
| bitmap_value_insert_into_set (s2, var); |
| } |
| |
| |
| /* Given a unary or binary expression EXPR, create and return a new |
| expression with the same structure as EXPR but with its operands |
| replaced with the value handles of each of the operands of EXPR. |
| Insert EXPR's operands into the EXP_GEN set for BLOCK. |
| |
| VUSES represent the virtual use operands associated with EXPR (if |
| any). They are used when computing the hash value for EXPR. */ |
| |
| static inline tree |
| create_value_expr_from (tree expr, basic_block block, vuse_optype vuses) |
| { |
| int i; |
| enum tree_code code = TREE_CODE (expr); |
| tree vexpr; |
| |
| gcc_assert (TREE_CODE_CLASS (code) == tcc_unary |
| || TREE_CODE_CLASS (code) == tcc_binary |
| || TREE_CODE_CLASS (code) == tcc_reference); |
| |
| if (TREE_CODE_CLASS (code) == tcc_unary) |
| vexpr = pool_alloc (unary_node_pool); |
| else if (TREE_CODE_CLASS (code) == tcc_reference) |
| vexpr = pool_alloc (reference_node_pool); |
| else |
| vexpr = pool_alloc (binary_node_pool); |
| |
| memcpy (vexpr, expr, tree_size (expr)); |
| |
| for (i = 0; i < TREE_CODE_LENGTH (code); i++) |
| { |
| tree op = TREE_OPERAND (expr, i); |
| if (op != NULL) |
| { |
| tree val = vn_lookup_or_add (op, vuses); |
| if (!is_undefined_value (op)) |
| value_insert_into_set (EXP_GEN (block), op); |
| if (TREE_CODE (val) == VALUE_HANDLE) |
| TREE_TYPE (val) = TREE_TYPE (TREE_OPERAND (vexpr, i)); |
| TREE_OPERAND (vexpr, i) = val; |
| } |
| } |
| |
| return vexpr; |
| } |
| |
| |
| /* Compute the AVAIL set for all basic blocks. |
| |
| This function performs value numbering of the statements in each basic |
| block. The AVAIL sets are built from information we glean while doing |
| this value numbering, since the AVAIL sets contain only one entry per |
| value. |
| |
| AVAIL_IN[BLOCK] = AVAIL_OUT[dom(BLOCK)]. |
| AVAIL_OUT[BLOCK] = AVAIL_IN[BLOCK] U PHI_GEN[BLOCK] U TMP_GEN[BLOCK]. */ |
| |
| static void |
| compute_avail (void) |
| { |
| basic_block block, son; |
| basic_block *worklist; |
| size_t sp = 0; |
| tree param; |
| |
| /* For arguments with default definitions, we pretend they are |
| defined in the entry block. */ |
| for (param = DECL_ARGUMENTS (current_function_decl); |
| param; |
| param = TREE_CHAIN (param)) |
| { |
| if (default_def (param) != NULL) |
| { |
| tree val; |
| tree def = default_def (param); |
| val = vn_lookup_or_add (def, NULL); |
| bitmap_insert_into_set (TMP_GEN (ENTRY_BLOCK_PTR), def); |
| bitmap_value_insert_into_set (AVAIL_OUT (ENTRY_BLOCK_PTR), def); |
| } |
| } |
| |
| /* Allocate the worklist. */ |
| worklist = xmalloc (sizeof (basic_block) * n_basic_blocks); |
| |
| /* Seed the algorithm by putting the dominator children of the entry |
| block on the worklist. */ |
| for (son = first_dom_son (CDI_DOMINATORS, ENTRY_BLOCK_PTR); |
| son; |
| son = next_dom_son (CDI_DOMINATORS, son)) |
| worklist[sp++] = son; |
| |
| /* Loop until the worklist is empty. */ |
| while (sp) |
| { |
| block_stmt_iterator bsi; |
| tree stmt, phi; |
| basic_block dom; |
| |
| /* Pick a block from the worklist. */ |
| block = worklist[--sp]; |
| |
| /* Initially, the set of available values in BLOCK is that of |
| its immediate dominator. */ |
| dom = get_immediate_dominator (CDI_DOMINATORS, block); |
| if (dom) |
| bitmap_set_copy (AVAIL_OUT (block), AVAIL_OUT (dom)); |
| |
| /* Generate values for PHI nodes. */ |
| for (phi = phi_nodes (block); phi; phi = PHI_CHAIN (phi)) |
| /* We have no need for virtual phis, as they don't represent |
| actual computations. */ |
| if (is_gimple_reg (PHI_RESULT (phi))) |
| add_to_sets (PHI_RESULT (phi), PHI_RESULT (phi), NULL, |
| PHI_GEN (block), AVAIL_OUT (block)); |
| |
| /* Now compute value numbers and populate value sets with all |
| the expressions computed in BLOCK. */ |
| for (bsi = bsi_start (block); !bsi_end_p (bsi); bsi_next (&bsi)) |
| { |
| stmt_ann_t ann; |
| size_t j; |
| |
| stmt = bsi_stmt (bsi); |
| ann = stmt_ann (stmt); |
| get_stmt_operands (stmt); |
| |
| /* We are only interested in assignments of the form |
| X_i = EXPR, where EXPR represents an "interesting" |
| computation, it has no volatile operands and X_i |
| doesn't flow through an abnormal edge. */ |
| if (TREE_CODE (stmt) == MODIFY_EXPR |
| && !ann->has_volatile_ops |
| && TREE_CODE (TREE_OPERAND (stmt, 0)) == SSA_NAME |
| && !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (TREE_OPERAND (stmt, 0))) |
| { |
| tree lhs = TREE_OPERAND (stmt, 0); |
| tree rhs = TREE_OPERAND (stmt, 1); |
| vuse_optype vuses = STMT_VUSE_OPS (stmt); |
| |
| STRIP_USELESS_TYPE_CONVERSION (rhs); |
| if (TREE_CODE (rhs) == SSA_NAME |
| || is_gimple_min_invariant (rhs)) |
| { |
| /* Compute a value number for the RHS of the statement |
| and add its value to the AVAIL_OUT set for the block. |
| Add the LHS to TMP_GEN. */ |
| add_to_sets (lhs, rhs, vuses, TMP_GEN (block), |
| AVAIL_OUT (block)); |
| |
| if (TREE_CODE (rhs) == SSA_NAME |
| && !is_undefined_value (rhs)) |
| value_insert_into_set (EXP_GEN (block), rhs); |
| continue; |
| } |
| else if (UNARY_CLASS_P (rhs) || BINARY_CLASS_P (rhs) |
| || TREE_CODE (rhs) == INDIRECT_REF) |
| { |
| /* For binary, unary, and reference expressions, |
| create a duplicate expression with the operands |
| replaced with the value handles of the original |
| RHS. */ |
| tree newt = create_value_expr_from (rhs, block, vuses); |
| add_to_sets (lhs, newt, vuses, TMP_GEN (block), |
| AVAIL_OUT (block)); |
| value_insert_into_set (EXP_GEN (block), newt); |
| continue; |
| } |
| } |
| |
| /* For any other statement that we don't recognize, simply |
| make the names generated by the statement available in |
| AVAIL_OUT and TMP_GEN. */ |
| for (j = 0; j < NUM_DEFS (STMT_DEF_OPS (stmt)); j++) |
| { |
| tree def = DEF_OP (STMT_DEF_OPS (stmt), j); |
| add_to_sets (def, def, NULL, TMP_GEN (block), |
| AVAIL_OUT (block)); |
| } |
| |
| for (j = 0; j < NUM_USES (STMT_USE_OPS (stmt)); j++) |
| { |
| tree use = USE_OP (STMT_USE_OPS (stmt), j); |
| add_to_sets (use, use, NULL, NULL, AVAIL_OUT (block)); |
| } |
| } |
| |
| /* Put the dominator children of BLOCK on the worklist of blocks |
| to compute available sets for. */ |
| for (son = first_dom_son (CDI_DOMINATORS, block); |
| son; |
| son = next_dom_son (CDI_DOMINATORS, son)) |
| worklist[sp++] = son; |
| } |
| |
| free (worklist); |
| } |
| |
| |
| /* Eliminate fully redundant computations. */ |
| |
| static void |
| eliminate (void) |
| { |
| basic_block b; |
| |
| FOR_EACH_BB (b) |
| { |
| block_stmt_iterator i; |
| |
| for (i = bsi_start (b); !bsi_end_p (i); bsi_next (&i)) |
| { |
| tree stmt = bsi_stmt (i); |
| |
| /* Lookup the RHS of the expression, see if we have an |
| available computation for it. If so, replace the RHS with |
| the available computation. */ |
| if (TREE_CODE (stmt) == MODIFY_EXPR |
| && TREE_CODE (TREE_OPERAND (stmt, 0)) == SSA_NAME |
| && TREE_CODE (TREE_OPERAND (stmt ,1)) != SSA_NAME |
| && !is_gimple_min_invariant (TREE_OPERAND (stmt, 1)) |
| && !stmt_ann (stmt)->has_volatile_ops) |
| { |
| tree lhs = TREE_OPERAND (stmt, 0); |
| tree *rhs_p = &TREE_OPERAND (stmt, 1); |
| tree sprime; |
| |
| sprime = bitmap_find_leader (AVAIL_OUT (b), |
| vn_lookup (lhs, NULL)); |
| if (sprime |
| && sprime != lhs |
| && (TREE_CODE (*rhs_p) != SSA_NAME |
| || may_propagate_copy (*rhs_p, sprime))) |
| { |
| gcc_assert (sprime != *rhs_p); |
| |
| if (dump_file && (dump_flags & TDF_DETAILS)) |
| { |
| fprintf (dump_file, "Replaced "); |
| print_generic_expr (dump_file, *rhs_p, 0); |
| fprintf (dump_file, " with "); |
| print_generic_expr (dump_file, sprime, 0); |
| fprintf (dump_file, " in "); |
| print_generic_stmt (dump_file, stmt, 0); |
| } |
| if (TREE_CODE (sprime) == SSA_NAME) |
| NECESSARY (SSA_NAME_DEF_STMT (sprime)) = 1; |
| pre_stats.eliminations++; |
| propagate_tree_value (rhs_p, sprime); |
| modify_stmt (stmt); |
| |
| /* If we removed EH side effects from the statement, clean |
| its EH information. */ |
| if (maybe_clean_eh_stmt (stmt)) |
| { |
| bitmap_set_bit (need_eh_cleanup, |
| bb_for_stmt (stmt)->index); |
| if (dump_file && (dump_flags & TDF_DETAILS)) |
| fprintf (dump_file, " Removed EH side effects.\n"); |
| } |
| } |
| } |
| } |
| } |
| } |
| |
| /* Borrow a bit of tree-ssa-dce.c for the moment. |
| XXX: In 4.1, we should be able to just run a DCE pass after PRE, though |
| this may be a bit faster, and we may want critical edges kept split. */ |
| |
| /* If OP's defining statement has not already been determined to be necessary, |
| mark that statement necessary. and place it on the WORKLIST. */ |
| |
| static inline void |
| mark_operand_necessary (tree op, VEC(tree_on_heap) **worklist) |
| { |
| tree stmt; |
| int ver; |
| |
| gcc_assert (op); |
| |
| ver = SSA_NAME_VERSION (op); |
| |
| stmt = SSA_NAME_DEF_STMT (op); |
| gcc_assert (stmt); |
| |
| if (NECESSARY (stmt) |
| || IS_EMPTY_STMT (stmt)) |
| return; |
| |
| NECESSARY (stmt) = 1; |
| VEC_safe_push (tree_on_heap, *worklist, stmt); |
| } |
| |
| /* Because we don't follow exactly the standard PRE algorithm, and decide not |
| to insert PHI nodes sometimes, and because value numbering of casts isn't |
| perfect, we sometimes end up inserting dead code. This simple DCE-like |
| pass removes any insertions we made that weren't actually used. */ |
| |
| static void |
| remove_dead_inserted_code (void) |
| { |
| VEC (tree_on_heap) *worklist = NULL; |
| int i; |
| tree t; |
| |
| for (i = 0; VEC_iterate (tree_on_heap, inserted_exprs, i, t); i++) |
| { |
| if (NECESSARY (t)) |
| VEC_safe_push (tree_on_heap, worklist, t); |
| } |
| while (VEC_length (tree_on_heap, worklist) > 0) |
| { |
| t = VEC_pop (tree_on_heap, worklist); |
| if (TREE_CODE (t) == PHI_NODE) |
| { |
| /* PHI nodes are somewhat special in that each PHI alternative has |
| data and control dependencies. All the statements feeding the |
| PHI node's arguments are always necessary. In aggressive mode, |
| we also consider the control dependent edges leading to the |
| predecessor block associated with each PHI alternative as |
| necessary. */ |
| int k; |
| for (k = 0; k < PHI_NUM_ARGS (t); k++) |
| { |
| tree arg = PHI_ARG_DEF (t, k); |
| if (TREE_CODE (arg) == SSA_NAME) |
| mark_operand_necessary (arg, &worklist); |
| } |
| } |
| else |
| { |
| /* Propagate through the operands. Examine all the USE, VUSE and |
| V_MAY_DEF operands in this statement. Mark all the statements |
| which feed this statement's uses as necessary. */ |
| ssa_op_iter iter; |
| tree use; |
| |
| get_stmt_operands (t); |
| |
| /* The operands of V_MAY_DEF expressions are also needed as they |
| represent potential definitions that may reach this |
| statement (V_MAY_DEF operands allow us to follow def-def |
| links). */ |
| |
| FOR_EACH_SSA_TREE_OPERAND (use, t, iter, SSA_OP_ALL_USES) |
| mark_operand_necessary (use, &worklist); |
| } |
| } |
| for (i = 0; VEC_iterate (tree_on_heap, inserted_exprs, i, t); i++) |
| { |
| if (!NECESSARY (t)) |
| { |
| block_stmt_iterator bsi; |
| if (dump_file && (dump_flags & TDF_DETAILS)) |
| { |
| fprintf (dump_file, "Removing unnecessary insertion:"); |
| print_generic_stmt (dump_file, t, 0); |
| } |
| if (TREE_CODE (t) == PHI_NODE) |
| { |
| remove_phi_node (t, NULL, bb_for_stmt (t)); |
| } |
| else |
| { |
| bsi = bsi_for_stmt (t); |
| bsi_remove (&bsi); |
| } |
| } |
| } |
| VEC_free (tree_on_heap, worklist); |
| } |
| /* Initialize data structures used by PRE. */ |
| |
| static void |
| init_pre (bool do_fre) |
| { |
| basic_block bb; |
| |
| inserted_exprs = NULL; |
| vn_init (); |
| if (!do_fre) |
| current_loops = loop_optimizer_init (dump_file); |
| connect_infinite_loops_to_exit (); |
| memset (&pre_stats, 0, sizeof (pre_stats)); |
| |
| /* If block 0 has more than one predecessor, it means that its PHI |
| nodes will have arguments coming from block -1. This creates |
| problems for several places in PRE that keep local arrays indexed |
| by block number. To prevent this, we split the edge coming from |
| ENTRY_BLOCK_PTR (FIXME, if ENTRY_BLOCK_PTR had an index number |
| different than -1 we wouldn't have to hack this. tree-ssa-dce.c |
| needs a similar change). */ |
| if (EDGE_COUNT (EDGE_SUCC (ENTRY_BLOCK_PTR, 0)->dest->preds) > 1) |
| if (!(EDGE_SUCC (ENTRY_BLOCK_PTR, 0)->flags & EDGE_ABNORMAL)) |
| split_edge (EDGE_SUCC (ENTRY_BLOCK_PTR, 0)); |
| |
| FOR_ALL_BB (bb) |
| bb->aux = xcalloc (1, sizeof (struct bb_value_sets)); |
| |
| bitmap_obstack_initialize (&grand_bitmap_obstack); |
| phi_translate_table = htab_create (511, expr_pred_trans_hash, |
| expr_pred_trans_eq, free); |
| value_set_pool = create_alloc_pool ("Value sets", |
| sizeof (struct value_set), 30); |
| bitmap_set_pool = create_alloc_pool ("Bitmap sets", |
| sizeof (struct bitmap_set), 30); |
| value_set_node_pool = create_alloc_pool ("Value set nodes", |
| sizeof (struct value_set_node), 30); |
| calculate_dominance_info (CDI_POST_DOMINATORS); |
| calculate_dominance_info (CDI_DOMINATORS); |
| binary_node_pool = create_alloc_pool ("Binary tree nodes", |
| tree_code_size (PLUS_EXPR), 30); |
| unary_node_pool = create_alloc_pool ("Unary tree nodes", |
| tree_code_size (NEGATE_EXPR), 30); |
| reference_node_pool = create_alloc_pool ("Reference tree nodes", |
| tree_code_size (ARRAY_REF), 30); |
| FOR_ALL_BB (bb) |
| { |
| EXP_GEN (bb) = set_new (true); |
| PHI_GEN (bb) = bitmap_set_new (); |
| TMP_GEN (bb) = bitmap_set_new (); |
| AVAIL_OUT (bb) = bitmap_set_new (); |
| } |
| |
| need_eh_cleanup = BITMAP_ALLOC (NULL); |
| } |
| |
| |
| /* Deallocate data structures used by PRE. */ |
| |
| static void |
| fini_pre (bool do_fre) |
| { |
| basic_block bb; |
| unsigned int i; |
| |
| VEC_free (tree_on_heap, inserted_exprs); |
| bitmap_obstack_release (&grand_bitmap_obstack); |
| free_alloc_pool (value_set_pool); |
| free_alloc_pool (bitmap_set_pool); |
| free_alloc_pool (value_set_node_pool); |
| free_alloc_pool (binary_node_pool); |
| free_alloc_pool (reference_node_pool); |
| free_alloc_pool (unary_node_pool); |
| htab_delete (phi_translate_table); |
| remove_fake_exit_edges (); |
| |
| FOR_ALL_BB (bb) |
| { |
| free (bb->aux); |
| bb->aux = NULL; |
| } |
| |
| free_dominance_info (CDI_POST_DOMINATORS); |
| vn_delete (); |
| |
| if (!bitmap_empty_p (need_eh_cleanup)) |
| { |
| tree_purge_all_dead_eh_edges (need_eh_cleanup); |
| cleanup_tree_cfg (); |
| } |
| |
| BITMAP_FREE (need_eh_cleanup); |
| |
| /* Wipe out pointers to VALUE_HANDLEs. In the not terribly distant |
| future we will want them to be persistent though. */ |
| for (i = 0; i < num_ssa_names; i++) |
| { |
| tree name = ssa_name (i); |
| |
| if (!name) |
| continue; |
| |
| if (SSA_NAME_VALUE (name) |
| && TREE_CODE (SSA_NAME_VALUE (name)) == VALUE_HANDLE) |
| SSA_NAME_VALUE (name) = NULL; |
| } |
| if (!do_fre && current_loops) |
| { |
| loop_optimizer_finalize (current_loops, dump_file); |
| current_loops = NULL; |
| } |
| } |
| |
| |
| /* Main entry point to the SSA-PRE pass. DO_FRE is true if the caller |
| only wants to do full redundancy elimination. */ |
| |
| static void |
| execute_pre (bool do_fre) |
| { |
| init_pre (do_fre); |
| |
| /* Collect and value number expressions computed in each basic block. */ |
| compute_avail (); |
| |
| if (dump_file && (dump_flags & TDF_DETAILS)) |
| { |
| basic_block bb; |
| |
| FOR_ALL_BB (bb) |
| { |
| print_value_set (dump_file, EXP_GEN (bb), "exp_gen", bb->index); |
| bitmap_print_value_set (dump_file, TMP_GEN (bb), "tmp_gen", |
| bb->index); |
| bitmap_print_value_set (dump_file, AVAIL_OUT (bb), "avail_out", |
| bb->index); |
| } |
| } |
| |
| /* Insert can get quite slow on an incredibly large number of basic |
| blocks due to some quadratic behavior. Until this behavior is |
| fixed, don't run it when he have an incredibly large number of |
| bb's. If we aren't going to run insert, there is no point in |
| computing ANTIC, either, even though it's plenty fast. */ |
| if (!do_fre && n_basic_blocks < 4000) |
| { |
| compute_antic (); |
| insert (); |
| } |
| |
| /* Remove all the redundant expressions. */ |
| eliminate (); |
| |
| |
| if (dump_file && (dump_flags & TDF_STATS)) |
| { |
| fprintf (dump_file, "Insertions:%d\n", pre_stats.insertions); |
| fprintf (dump_file, "New PHIs:%d\n", pre_stats.phis); |
| fprintf (dump_file, "Eliminated:%d\n", pre_stats.eliminations); |
| fprintf (dump_file, "Constified:%d\n", pre_stats.constified); |
| } |
| |
| bsi_commit_edge_inserts (); |
| if (!do_fre) |
| remove_dead_inserted_code (); |
| fini_pre (do_fre); |
| |
| } |
| |
| |
| /* Gate and execute functions for PRE. */ |
| |
| static void |
| do_pre (void) |
| { |
| execute_pre (false); |
| } |
| |
| static bool |
| gate_pre (void) |
| { |
| return flag_tree_pre != 0; |
| } |
| |
| struct tree_opt_pass pass_pre = |
| { |
| "pre", /* name */ |
| gate_pre, /* gate */ |
| do_pre, /* execute */ |
| NULL, /* sub */ |
| NULL, /* next */ |
| 0, /* static_pass_number */ |
| TV_TREE_PRE, /* tv_id */ |
| PROP_no_crit_edges | PROP_cfg |
| | PROP_ssa | PROP_alias, /* properties_required */ |
| 0, /* properties_provided */ |
| 0, /* properties_destroyed */ |
| 0, /* todo_flags_start */ |
| TODO_dump_func | TODO_ggc_collect | TODO_verify_ssa, /* todo_flags_finish */ |
| 0 /* letter */ |
| }; |
| |
| |
| /* Gate and execute functions for FRE. */ |
| |
| static void |
| do_fre (void) |
| { |
| execute_pre (true); |
| } |
| |
| static bool |
| gate_fre (void) |
| { |
| return flag_tree_fre != 0; |
| } |
| |
| struct tree_opt_pass pass_fre = |
| { |
| "fre", /* name */ |
| gate_fre, /* gate */ |
| do_fre, /* execute */ |
| NULL, /* sub */ |
| NULL, /* next */ |
| 0, /* static_pass_number */ |
| TV_TREE_FRE, /* tv_id */ |
| PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */ |
| 0, /* properties_provided */ |
| 0, /* properties_destroyed */ |
| 0, /* todo_flags_start */ |
| TODO_dump_func | TODO_ggc_collect | TODO_verify_ssa, /* todo_flags_finish */ |
| 0 /* letter */ |
| }; |