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llvm / llvm-archive / 48649d2c83b557841c9e5c978d9ab5af13cb52e5 / . / llvm-gcc-4.0 / gcc / flow.c
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/* Data flow analysis for GNU compiler.
Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
1999, 2000, 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
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. */
/* This file contains the data flow analysis pass of the compiler. It
computes data flow information which tells combine_instructions
which insns to consider combining and controls register allocation.
Additional data flow information that is too bulky to record is
generated during the analysis, and is used at that time to create
autoincrement and autodecrement addressing.
The first step is dividing the function into basic blocks.
find_basic_blocks does this. Then life_analysis determines
where each register is live and where it is dead.
** find_basic_blocks **
find_basic_blocks divides the current function's rtl into basic
blocks and constructs the CFG. The blocks are recorded in the
basic_block_info array; the CFG exists in the edge structures
referenced by the blocks.
find_basic_blocks also finds any unreachable loops and deletes them.
** life_analysis **
life_analysis is called immediately after find_basic_blocks.
It uses the basic block information to determine where each
hard or pseudo register is live.
** live-register info **
The information about where each register is live is in two parts:
the REG_NOTES of insns, and the vector basic_block->global_live_at_start.
basic_block->global_live_at_start has an element for each basic
block, and the element is a bit-vector with a bit for each hard or
pseudo register. The bit is 1 if the register is live at the
beginning of the basic block.
Two types of elements can be added to an insn's REG_NOTES.
A REG_DEAD note is added to an insn's REG_NOTES for any register
that meets both of two conditions: The value in the register is not
needed in subsequent insns and the insn does not replace the value in
the register (in the case of multi-word hard registers, the value in
each register must be replaced by the insn to avoid a REG_DEAD note).
In the vast majority of cases, an object in a REG_DEAD note will be
used somewhere in the insn. The (rare) exception to this is if an
insn uses a multi-word hard register and only some of the registers are
needed in subsequent insns. In that case, REG_DEAD notes will be
provided for those hard registers that are not subsequently needed.
Partial REG_DEAD notes of this type do not occur when an insn sets
only some of the hard registers used in such a multi-word operand;
omitting REG_DEAD notes for objects stored in an insn is optional and
the desire to do so does not justify the complexity of the partial
REG_DEAD notes.
REG_UNUSED notes are added for each register that is set by the insn
but is unused subsequently (if every register set by the insn is unused
and the insn does not reference memory or have some other side-effect,
the insn is deleted instead). If only part of a multi-word hard
register is used in a subsequent insn, REG_UNUSED notes are made for
the parts that will not be used.
To determine which registers are live after any insn, one can
start from the beginning of the basic block and scan insns, noting
which registers are set by each insn and which die there.
** Other actions of life_analysis **
life_analysis sets up the LOG_LINKS fields of insns because the
information needed to do so is readily available.
life_analysis deletes insns whose only effect is to store a value
that is never used.
life_analysis notices cases where a reference to a register as
a memory address can be combined with a preceding or following
incrementation or decrementation of the register. The separate
instruction to increment or decrement is deleted and the address
is changed to a POST_INC or similar rtx.
Each time an incrementing or decrementing address is created,
a REG_INC element is added to the insn's REG_NOTES list.
life_analysis fills in certain vectors containing information about
register usage: REG_N_REFS, REG_N_DEATHS, REG_N_SETS, REG_LIVE_LENGTH,
REG_N_CALLS_CROSSED and REG_BASIC_BLOCK.
life_analysis sets current_function_sp_is_unchanging if the function
doesn't modify the stack pointer. */
/* TODO:
Split out from life_analysis:
- local property discovery
- global property computation
- log links creation
- pre/post modify transformation
*/
#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "tree.h"
#include "rtl.h"
#include "tm_p.h"
#include "hard-reg-set.h"
#include "basic-block.h"
#include "insn-config.h"
#include "regs.h"
#include "flags.h"
#include "output.h"
#include "function.h"
#include "except.h"
#include "toplev.h"
#include "recog.h"
#include "expr.h"
#include "timevar.h"
#include "obstack.h"
#include "splay-tree.h"
#ifndef HAVE_epilogue
#define HAVE_epilogue 0
#endif
#ifndef HAVE_prologue
#define HAVE_prologue 0
#endif
#ifndef HAVE_sibcall_epilogue
#define HAVE_sibcall_epilogue 0
#endif
#ifndef EPILOGUE_USES
#define EPILOGUE_USES(REGNO) 0
#endif
#ifndef EH_USES
#define EH_USES(REGNO) 0
#endif
#ifdef HAVE_conditional_execution
#ifndef REVERSE_CONDEXEC_PREDICATES_P
#define REVERSE_CONDEXEC_PREDICATES_P(x, y) \
(GET_CODE ((x)) == reversed_comparison_code ((y), NULL))
#endif
#endif
/* This is the maximum number of times we process any given block if the
latest loop depth count is smaller than this number. Only used for the
failure strategy to avoid infinite loops in calculate_global_regs_live. */
#define MAX_LIVENESS_ROUNDS 20
/* Nonzero if the second flow pass has completed. */
int flow2_completed;
/* Maximum register number used in this function, plus one. */
int max_regno;
/* Indexed by n, giving various register information */
varray_type reg_n_info;
/* Regset of regs live when calls to `setjmp'-like functions happen. */
/* ??? Does this exist only for the setjmp-clobbered warning message? */
regset regs_live_at_setjmp;
/* List made of EXPR_LIST rtx's which gives pairs of pseudo registers
that have to go in the same hard reg.
The first two regs in the list are a pair, and the next two
are another pair, etc. */
rtx regs_may_share;
/* Set of registers that may be eliminable. These are handled specially
in updating regs_ever_live. */
static HARD_REG_SET elim_reg_set;
/* Holds information for tracking conditional register life information. */
struct reg_cond_life_info
{
/* A boolean expression of conditions under which a register is dead. */
rtx condition;
/* Conditions under which a register is dead at the basic block end. */
rtx orig_condition;
/* A boolean expression of conditions under which a register has been
stored into. */
rtx stores;
/* ??? Could store mask of bytes that are dead, so that we could finally
track lifetimes of multi-word registers accessed via subregs. */
};
/* For use in communicating between propagate_block and its subroutines.
Holds all information needed to compute life and def-use information. */
struct propagate_block_info
{
/* The basic block we're considering. */
basic_block bb;
/* Bit N is set if register N is conditionally or unconditionally live. */
regset reg_live;
/* Bit N is set if register N is set this insn. */
regset new_set;
/* Element N is the next insn that uses (hard or pseudo) register N
within the current basic block; or zero, if there is no such insn. */
rtx *reg_next_use;
/* Contains a list of all the MEMs we are tracking for dead store
elimination. */
rtx mem_set_list;
/* If non-null, record the set of registers set unconditionally in the
basic block. */
regset local_set;
/* If non-null, record the set of registers set conditionally in the
basic block. */
regset cond_local_set;
#ifdef HAVE_conditional_execution
/* Indexed by register number, holds a reg_cond_life_info for each
register that is not unconditionally live or dead. */
splay_tree reg_cond_dead;
/* Bit N is set if register N is in an expression in reg_cond_dead. */
regset reg_cond_reg;
#endif
/* The length of mem_set_list. */
int mem_set_list_len;
/* Nonzero if the value of CC0 is live. */
int cc0_live;
/* Flags controlling the set of information propagate_block collects. */
int flags;
/* Index of instruction being processed. */
int insn_num;
};
/* Number of dead insns removed. */
static int ndead;
/* When PROP_REG_INFO set, array contains pbi->insn_num of instruction
where given register died. When the register is marked alive, we use the
information to compute amount of instructions life range cross.
(remember, we are walking backward). This can be computed as current
pbi->insn_num - reg_deaths[regno].
At the end of processing each basic block, the remaining live registers
are inspected and liferanges are increased same way so liverange of global
registers are computed correctly.
The array is maintained clear for dead registers, so it can be safely reused
for next basic block without expensive memset of the whole array after
reseting pbi->insn_num to 0. */
static int *reg_deaths;
/* Maximum length of pbi->mem_set_list before we start dropping
new elements on the floor. */
#define MAX_MEM_SET_LIST_LEN 100
/* Forward declarations */
static int verify_wide_reg_1 (rtx *, void *);
static void verify_wide_reg (int, basic_block);
static void verify_local_live_at_start (regset, basic_block);
static void notice_stack_pointer_modification_1 (rtx, rtx, void *);
static void notice_stack_pointer_modification (void);
static void mark_reg (rtx, void *);
static void mark_regs_live_at_end (regset);
static void calculate_global_regs_live (sbitmap, sbitmap, int);
static void propagate_block_delete_insn (rtx);
static rtx propagate_block_delete_libcall (rtx, rtx);
static int insn_dead_p (struct propagate_block_info *, rtx, int, rtx);
static int libcall_dead_p (struct propagate_block_info *, rtx, rtx);
static void mark_set_regs (struct propagate_block_info *, rtx, rtx);
static void mark_set_1 (struct propagate_block_info *, enum rtx_code, rtx,
rtx, rtx, int);
static int find_regno_partial (rtx *, void *);
#ifdef HAVE_conditional_execution
static int mark_regno_cond_dead (struct propagate_block_info *, int, rtx);
static void free_reg_cond_life_info (splay_tree_value);
static int flush_reg_cond_reg_1 (splay_tree_node, void *);
static void flush_reg_cond_reg (struct propagate_block_info *, int);
static rtx elim_reg_cond (rtx, unsigned int);
static rtx ior_reg_cond (rtx, rtx, int);
static rtx not_reg_cond (rtx);
static rtx and_reg_cond (rtx, rtx, int);
#endif
#ifdef AUTO_INC_DEC
static void attempt_auto_inc (struct propagate_block_info *, rtx, rtx, rtx,
rtx, rtx);
static void find_auto_inc (struct propagate_block_info *, rtx, rtx);
static int try_pre_increment_1 (struct propagate_block_info *, rtx);
static int try_pre_increment (rtx, rtx, HOST_WIDE_INT);
#endif
static void mark_used_reg (struct propagate_block_info *, rtx, rtx, rtx);
static void mark_used_regs (struct propagate_block_info *, rtx, rtx, rtx);
void debug_flow_info (void);
static void add_to_mem_set_list (struct propagate_block_info *, rtx);
static int invalidate_mems_from_autoinc (rtx *, void *);
static void invalidate_mems_from_set (struct propagate_block_info *, rtx);
static void clear_log_links (sbitmap);
static int count_or_remove_death_notes_bb (basic_block, int);
static void allocate_bb_life_data (void);
/* Return the INSN immediately following the NOTE_INSN_BASIC_BLOCK
note associated with the BLOCK. */
rtx
first_insn_after_basic_block_note (basic_block block)
{
rtx insn;
/* Get the first instruction in the block. */
insn = BB_HEAD (block);
if (insn == NULL_RTX)
return NULL_RTX;
if (LABEL_P (insn))
insn = NEXT_INSN (insn);
gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn));
return NEXT_INSN (insn);
}
/* Perform data flow analysis for the whole control flow graph.
FLAGS is a set of PROP_* flags to be used in accumulating flow info. */
void
life_analysis (FILE *file, int flags)
{
#ifdef ELIMINABLE_REGS
int i;
static const struct {const int from, to; } eliminables[] = ELIMINABLE_REGS;
#endif
/* Record which registers will be eliminated. We use this in
mark_used_regs. */
CLEAR_HARD_REG_SET (elim_reg_set);
#ifdef ELIMINABLE_REGS
for (i = 0; i < (int) ARRAY_SIZE (eliminables); i++)
SET_HARD_REG_BIT (elim_reg_set, eliminables[i].from);
#else
SET_HARD_REG_BIT (elim_reg_set, FRAME_POINTER_REGNUM);
#endif
#ifdef CANNOT_CHANGE_MODE_CLASS
if (flags & PROP_REG_INFO)
init_subregs_of_mode ();
#endif
if (! optimize)
flags &= ~(PROP_LOG_LINKS | PROP_AUTOINC | PROP_ALLOW_CFG_CHANGES);
/* The post-reload life analysis have (on a global basis) the same
registers live as was computed by reload itself. elimination
Otherwise offsets and such may be incorrect.
Reload will make some registers as live even though they do not
appear in the rtl.
We don't want to create new auto-incs after reload, since they
are unlikely to be useful and can cause problems with shared
stack slots. */
if (reload_completed)
flags &= ~(PROP_REG_INFO | PROP_AUTOINC);
/* We want alias analysis information for local dead store elimination. */
if (optimize && (flags & PROP_SCAN_DEAD_STORES))
init_alias_analysis ();
/* Always remove no-op moves. Do this before other processing so
that we don't have to keep re-scanning them. */
delete_noop_moves ();
/* Some targets can emit simpler epilogues if they know that sp was
not ever modified during the function. After reload, of course,
we've already emitted the epilogue so there's no sense searching. */
if (! reload_completed)
notice_stack_pointer_modification ();
/* Allocate and zero out data structures that will record the
data from lifetime analysis. */
allocate_reg_life_data ();
allocate_bb_life_data ();
/* Find the set of registers live on function exit. */
mark_regs_live_at_end (EXIT_BLOCK_PTR->global_live_at_start);
/* "Update" life info from zero. It'd be nice to begin the
relaxation with just the exit and noreturn blocks, but that set
is not immediately handy. */
if (flags & PROP_REG_INFO)
{
memset (regs_ever_live, 0, sizeof (regs_ever_live));
memset (regs_asm_clobbered, 0, sizeof (regs_asm_clobbered));
}
update_life_info (NULL, UPDATE_LIFE_GLOBAL, flags);
if (reg_deaths)
{
free (reg_deaths);
reg_deaths = NULL;
}
/* Clean up. */
if (optimize && (flags & PROP_SCAN_DEAD_STORES))
end_alias_analysis ();
if (file)
dump_flow_info (file);
/* Removing dead insns should have made jumptables really dead. */
delete_dead_jumptables ();
}
/* A subroutine of verify_wide_reg, called through for_each_rtx.
Search for REGNO. If found, return 2 if it is not wider than
word_mode. */
static int
verify_wide_reg_1 (rtx *px, void *pregno)
{
rtx x = *px;
unsigned int regno = *(int *) pregno;
if (REG_P (x) && REGNO (x) == regno)
{
if (GET_MODE_BITSIZE (GET_MODE (x)) <= BITS_PER_WORD)
return 2;
return 1;
}
return 0;
}
/* A subroutine of verify_local_live_at_start. Search through insns
of BB looking for register REGNO. */
static void
verify_wide_reg (int regno, basic_block bb)
{
rtx head = BB_HEAD (bb), end = BB_END (bb);
while (1)
{
if (INSN_P (head))
{
int r = for_each_rtx (&PATTERN (head), verify_wide_reg_1, &regno);
if (r == 1)
return;
if (r == 2)
break;
}
if (head == end)
break;
head = NEXT_INSN (head);
}
if (dump_file)
{
fprintf (dump_file, "Register %d died unexpectedly.\n", regno);
dump_bb (bb, dump_file, 0);
}
fatal_error ("internal consistency failure");
}
/* A subroutine of update_life_info. Verify that there are no untoward
changes in live_at_start during a local update. */
static void
verify_local_live_at_start (regset new_live_at_start, basic_block bb)
{
if (reload_completed)
{
/* After reload, there are no pseudos, nor subregs of multi-word
registers. The regsets should exactly match. */
if (! REG_SET_EQUAL_P (new_live_at_start, bb->global_live_at_start))
{
if (dump_file)
{
fprintf (dump_file,
"live_at_start mismatch in bb %d, aborting\nNew:\n",
bb->index);
debug_bitmap_file (dump_file, new_live_at_start);
fputs ("Old:\n", dump_file);
dump_bb (bb, dump_file, 0);
}
fatal_error ("internal consistency failure");
}
}
else
{
unsigned i;
reg_set_iterator rsi;
/* Find the set of changed registers. */
XOR_REG_SET (new_live_at_start, bb->global_live_at_start);
EXECUTE_IF_SET_IN_REG_SET (new_live_at_start, 0, i, rsi)
{
/* No registers should die. */
if (REGNO_REG_SET_P (bb->global_live_at_start, i))
{
if (dump_file)
{
fprintf (dump_file,
"Register %d died unexpectedly.\n", i);
dump_bb (bb, dump_file, 0);
}
fatal_error ("internal consistency failure");
}
/* Verify that the now-live register is wider than word_mode. */
verify_wide_reg (i, bb);
}
}
}
/* Updates life information starting with the basic blocks set in BLOCKS.
If BLOCKS is null, consider it to be the universal set.
If EXTENT is UPDATE_LIFE_LOCAL, such as after splitting or peepholing,
we are only expecting local modifications to basic blocks. If we find
extra registers live at the beginning of a block, then we either killed
useful data, or we have a broken split that wants data not provided.
If we find registers removed from live_at_start, that means we have
a broken peephole that is killing a register it shouldn't.
??? This is not true in one situation -- when a pre-reload splitter
generates subregs of a multi-word pseudo, current life analysis will
lose the kill. So we _can_ have a pseudo go live. How irritating.
It is also not true when a peephole decides that it doesn't need one
or more of the inputs.
Including PROP_REG_INFO does not properly refresh regs_ever_live
unless the caller resets it to zero. */
int
update_life_info (sbitmap blocks, enum update_life_extent extent,
int prop_flags)
{
regset tmp;
unsigned i;
int stabilized_prop_flags = prop_flags;
basic_block bb;
tmp = ALLOC_REG_SET (&reg_obstack);
ndead = 0;
if ((prop_flags & PROP_REG_INFO) && !reg_deaths)
reg_deaths = xcalloc (sizeof (*reg_deaths), max_regno);
timevar_push ((extent == UPDATE_LIFE_LOCAL || blocks)
? TV_LIFE_UPDATE : TV_LIFE);
/* Changes to the CFG are only allowed when
doing a global update for the entire CFG. */
gcc_assert (!(prop_flags & PROP_ALLOW_CFG_CHANGES)
|| (extent != UPDATE_LIFE_LOCAL && !blocks));
/* For a global update, we go through the relaxation process again. */
if (extent != UPDATE_LIFE_LOCAL)
{
for ( ; ; )
{
int changed = 0;
calculate_global_regs_live (blocks, blocks,
prop_flags & (PROP_SCAN_DEAD_CODE
| PROP_SCAN_DEAD_STORES
| PROP_ALLOW_CFG_CHANGES));
if ((prop_flags & (PROP_KILL_DEAD_CODE | PROP_ALLOW_CFG_CHANGES))
!= (PROP_KILL_DEAD_CODE | PROP_ALLOW_CFG_CHANGES))
break;
/* Removing dead code may allow the CFG to be simplified which
in turn may allow for further dead code detection / removal. */
FOR_EACH_BB_REVERSE (bb)
{
COPY_REG_SET (tmp, bb->global_live_at_end);
changed |= propagate_block (bb, tmp, NULL, NULL,
prop_flags & (PROP_SCAN_DEAD_CODE
| PROP_SCAN_DEAD_STORES
| PROP_KILL_DEAD_CODE));
}
/* Don't pass PROP_SCAN_DEAD_CODE or PROP_KILL_DEAD_CODE to
subsequent propagate_block calls, since removing or acting as
removing dead code can affect global register liveness, which
is supposed to be finalized for this call after this loop. */
stabilized_prop_flags
&= ~(PROP_SCAN_DEAD_CODE | PROP_SCAN_DEAD_STORES
| PROP_KILL_DEAD_CODE);
if (! changed)
break;
/* We repeat regardless of what cleanup_cfg says. If there were
instructions deleted above, that might have been only a
partial improvement (see MAX_MEM_SET_LIST_LEN usage).
Further improvement may be possible. */
cleanup_cfg (CLEANUP_EXPENSIVE);
/* Zap the life information from the last round. If we don't
do this, we can wind up with registers that no longer appear
in the code being marked live at entry. */
FOR_EACH_BB (bb)
{
CLEAR_REG_SET (bb->global_live_at_start);
CLEAR_REG_SET (bb->global_live_at_end);
}
}
/* If asked, remove notes from the blocks we'll update. */
if (extent == UPDATE_LIFE_GLOBAL_RM_NOTES)
count_or_remove_death_notes (blocks, 1);
}
/* Clear log links in case we are asked to (re)compute them. */
if (prop_flags & PROP_LOG_LINKS)
clear_log_links (blocks);
if (blocks)
{
EXECUTE_IF_SET_IN_SBITMAP (blocks, 0, i,
{
bb = BASIC_BLOCK (i);
COPY_REG_SET (tmp, bb->global_live_at_end);
propagate_block (bb, tmp, NULL, NULL, stabilized_prop_flags);
if (extent == UPDATE_LIFE_LOCAL)
verify_local_live_at_start (tmp, bb);
});
}
else
{
FOR_EACH_BB_REVERSE (bb)
{
COPY_REG_SET (tmp, bb->global_live_at_end);
propagate_block (bb, tmp, NULL, NULL, stabilized_prop_flags);
if (extent == UPDATE_LIFE_LOCAL)
verify_local_live_at_start (tmp, bb);
}
}
FREE_REG_SET (tmp);
if (prop_flags & PROP_REG_INFO)
{
reg_set_iterator rsi;
/* The only pseudos that are live at the beginning of the function
are those that were not set anywhere in the function. local-alloc
doesn't know how to handle these correctly, so mark them as not
local to any one basic block. */
EXECUTE_IF_SET_IN_REG_SET (ENTRY_BLOCK_PTR->global_live_at_end,
FIRST_PSEUDO_REGISTER, i, rsi)
REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL;
/* We have a problem with any pseudoreg that lives across the setjmp.
ANSI says that if a user variable does not change in value between
the setjmp and the longjmp, then the longjmp preserves it. This
includes longjmp from a place where the pseudo appears dead.
(In principle, the value still exists if it is in scope.)
If the pseudo goes in a hard reg, some other value may occupy
that hard reg where this pseudo is dead, thus clobbering the pseudo.
Conclusion: such a pseudo must not go in a hard reg. */
EXECUTE_IF_SET_IN_REG_SET (regs_live_at_setjmp,
FIRST_PSEUDO_REGISTER, i, rsi)
{
if (regno_reg_rtx[i] != 0)
{
REG_LIVE_LENGTH (i) = -1;
REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
}
}
}
if (reg_deaths)
{
free (reg_deaths);
reg_deaths = NULL;
}
timevar_pop ((extent == UPDATE_LIFE_LOCAL || blocks)
? TV_LIFE_UPDATE : TV_LIFE);
if (ndead && dump_file)
fprintf (dump_file, "deleted %i dead insns\n", ndead);
return ndead;
}
/* Update life information in all blocks where BB_DIRTY is set. */
int
update_life_info_in_dirty_blocks (enum update_life_extent extent, int prop_flags)
{
sbitmap update_life_blocks = sbitmap_alloc (last_basic_block);
int n = 0;
basic_block bb;
int retval = 0;
sbitmap_zero (update_life_blocks);
FOR_EACH_BB (bb)
{
if (bb->flags & BB_DIRTY)
{
SET_BIT (update_life_blocks, bb->index);
n++;
}
}
if (n)
retval = update_life_info (update_life_blocks, extent, prop_flags);
sbitmap_free (update_life_blocks);
return retval;
}
/* Free the variables allocated by find_basic_blocks. */
void
free_basic_block_vars (void)
{
if (basic_block_info)
{
clear_edges ();
basic_block_info = NULL;
}
n_basic_blocks = 0;
last_basic_block = 0;
ENTRY_BLOCK_PTR->aux = NULL;
ENTRY_BLOCK_PTR->global_live_at_end = NULL;
EXIT_BLOCK_PTR->aux = NULL;
EXIT_BLOCK_PTR->global_live_at_start = NULL;
}
/* Delete any insns that copy a register to itself. */
int
delete_noop_moves (void)
{
rtx insn, next;
basic_block bb;
int nnoops = 0;
FOR_EACH_BB (bb)
{
for (insn = BB_HEAD (bb); insn != NEXT_INSN (BB_END (bb)); insn = next)
{
next = NEXT_INSN (insn);
if (INSN_P (insn) && noop_move_p (insn))
{
rtx note;
/* If we're about to remove the first insn of a libcall
then move the libcall note to the next real insn and
update the retval note. */
if ((note = find_reg_note (insn, REG_LIBCALL, NULL_RTX))
&& XEXP (note, 0) != insn)
{
rtx new_libcall_insn = next_real_insn (insn);
rtx retval_note = find_reg_note (XEXP (note, 0),
REG_RETVAL, NULL_RTX);
REG_NOTES (new_libcall_insn)
= gen_rtx_INSN_LIST (REG_LIBCALL, XEXP (note, 0),
REG_NOTES (new_libcall_insn));
XEXP (retval_note, 0) = new_libcall_insn;
}
delete_insn_and_edges (insn);
nnoops++;
}
}
}
if (nnoops && dump_file)
fprintf (dump_file, "deleted %i noop moves", nnoops);
return nnoops;
}
/* Delete any jump tables never referenced. We can't delete them at the
time of removing tablejump insn as they are referenced by the preceding
insns computing the destination, so we delay deleting and garbagecollect
them once life information is computed. */
void
delete_dead_jumptables (void)
{
basic_block bb;
/* A dead jump table does not belong to any basic block. Scan insns
between two adjacent basic blocks. */
FOR_EACH_BB (bb)
{
rtx insn, next;
for (insn = NEXT_INSN (BB_END (bb));
insn && !NOTE_INSN_BASIC_BLOCK_P (insn);
insn = next)
{
next = NEXT_INSN (insn);
if (LABEL_P (insn)
&& LABEL_NUSES (insn) == LABEL_PRESERVE_P (insn)
&& JUMP_P (next)
&& (GET_CODE (PATTERN (next)) == ADDR_VEC
|| GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
{
rtx label = insn, jump = next;
if (dump_file)
fprintf (dump_file, "Dead jumptable %i removed\n",
INSN_UID (insn));
next = NEXT_INSN (next);
delete_insn (jump);
delete_insn (label);
}
}
}
}
/* Determine if the stack pointer is constant over the life of the function.
Only useful before prologues have been emitted. */
static void
notice_stack_pointer_modification_1 (rtx x, rtx pat ATTRIBUTE_UNUSED,
void *data ATTRIBUTE_UNUSED)
{
if (x == stack_pointer_rtx
/* The stack pointer is only modified indirectly as the result
of a push until later in flow. See the comments in rtl.texi
regarding Embedded Side-Effects on Addresses. */
|| (MEM_P (x)
&& GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == RTX_AUTOINC
&& XEXP (XEXP (x, 0), 0) == stack_pointer_rtx))
current_function_sp_is_unchanging = 0;
}
static void
notice_stack_pointer_modification (void)
{
basic_block bb;
rtx insn;
/* Assume that the stack pointer is unchanging if alloca hasn't
been used. */
current_function_sp_is_unchanging = !current_function_calls_alloca;
if (! current_function_sp_is_unchanging)
return;
FOR_EACH_BB (bb)
FOR_BB_INSNS (bb, insn)
{
if (INSN_P (insn))
{
/* Check if insn modifies the stack pointer. */
note_stores (PATTERN (insn),
notice_stack_pointer_modification_1,
NULL);
if (! current_function_sp_is_unchanging)
return;
}
}
}
/* Mark a register in SET. Hard registers in large modes get all
of their component registers set as well. */
static void
mark_reg (rtx reg, void *xset)
{
regset set = (regset) xset;
int regno = REGNO (reg);
gcc_assert (GET_MODE (reg) != BLKmode);
SET_REGNO_REG_SET (set, regno);
if (regno < FIRST_PSEUDO_REGISTER)
{
int n = hard_regno_nregs[regno][GET_MODE (reg)];
while (--n > 0)
SET_REGNO_REG_SET (set, regno + n);
}
}
/* Mark those regs which are needed at the end of the function as live
at the end of the last basic block. */
static void
mark_regs_live_at_end (regset set)
{
unsigned int i;
/* If exiting needs the right stack value, consider the stack pointer
live at the end of the function. */
if ((HAVE_epilogue && epilogue_completed)
|| ! EXIT_IGNORE_STACK
|| (! FRAME_POINTER_REQUIRED
&& ! current_function_calls_alloca
&& flag_omit_frame_pointer)
|| current_function_sp_is_unchanging)
{
SET_REGNO_REG_SET (set, STACK_POINTER_REGNUM);
}
/* Mark the frame pointer if needed at the end of the function. If
we end up eliminating it, it will be removed from the live list
of each basic block by reload. */
if (! reload_completed || frame_pointer_needed)
{
SET_REGNO_REG_SET (set, FRAME_POINTER_REGNUM);
#if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
/* If they are different, also mark the hard frame pointer as live. */
if (! LOCAL_REGNO (HARD_FRAME_POINTER_REGNUM))
SET_REGNO_REG_SET (set, HARD_FRAME_POINTER_REGNUM);
#endif
}
#ifndef PIC_OFFSET_TABLE_REG_CALL_CLOBBERED
/* Many architectures have a GP register even without flag_pic.
Assume the pic register is not in use, or will be handled by
other means, if it is not fixed. */
if ((unsigned) PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
&& fixed_regs[PIC_OFFSET_TABLE_REGNUM])
SET_REGNO_REG_SET (set, PIC_OFFSET_TABLE_REGNUM);
#endif
/* Mark all global registers, and all registers used by the epilogue
as being live at the end of the function since they may be
referenced by our caller. */
for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
if (global_regs[i] || EPILOGUE_USES (i))
SET_REGNO_REG_SET (set, i);
if (HAVE_epilogue && epilogue_completed)
{
/* Mark all call-saved registers that we actually used. */
for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
if (regs_ever_live[i] && ! LOCAL_REGNO (i)
&& ! TEST_HARD_REG_BIT (regs_invalidated_by_call, i))
SET_REGNO_REG_SET (set, i);
}
#ifdef EH_RETURN_DATA_REGNO
/* Mark the registers that will contain data for the handler. */
if (reload_completed && current_function_calls_eh_return)
for (i = 0; ; ++i)
{
unsigned regno = EH_RETURN_DATA_REGNO(i);
if (regno == INVALID_REGNUM)
break;
SET_REGNO_REG_SET (set, regno);
}
#endif
#ifdef EH_RETURN_STACKADJ_RTX
if ((! HAVE_epilogue || ! epilogue_completed)
&& current_function_calls_eh_return)
{
rtx tmp = EH_RETURN_STACKADJ_RTX;
if (tmp && REG_P (tmp))
mark_reg (tmp, set);
}
#endif
#ifdef EH_RETURN_HANDLER_RTX
if ((! HAVE_epilogue || ! epilogue_completed)
&& current_function_calls_eh_return)
{
rtx tmp = EH_RETURN_HANDLER_RTX;
if (tmp && REG_P (tmp))
mark_reg (tmp, set);
}
#endif
/* Mark function return value. */
diddle_return_value (mark_reg, set);
}
/* Propagate global life info around the graph of basic blocks. Begin
considering blocks with their corresponding bit set in BLOCKS_IN.
If BLOCKS_IN is null, consider it the universal set.
BLOCKS_OUT is set for every block that was changed. */
static void
calculate_global_regs_live (sbitmap blocks_in, sbitmap blocks_out, int flags)
{
basic_block *queue, *qhead, *qtail, *qend, bb;
regset tmp, new_live_at_end, invalidated_by_call;
regset registers_made_dead;
bool failure_strategy_required = false;
int *block_accesses;
/* The registers that are modified within this in block. */
regset *local_sets;
/* The registers that are conditionally modified within this block.
In other words, regs that are set only as part of a COND_EXEC. */
regset *cond_local_sets;
int i;
/* Some passes used to forget clear aux field of basic block causing
sick behavior here. */
#ifdef ENABLE_CHECKING
FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
gcc_assert (!bb->aux);
#endif
tmp = ALLOC_REG_SET (&reg_obstack);
new_live_at_end = ALLOC_REG_SET (&reg_obstack);
invalidated_by_call = ALLOC_REG_SET (&reg_obstack);
registers_made_dead = ALLOC_REG_SET (&reg_obstack);
/* Inconveniently, this is only readily available in hard reg set form. */
for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i)
if (TEST_HARD_REG_BIT (regs_invalidated_by_call, i))
SET_REGNO_REG_SET (invalidated_by_call, i);
/* Allocate space for the sets of local properties. */
local_sets = xcalloc (last_basic_block - (INVALID_BLOCK + 1),
sizeof (regset));
cond_local_sets = xcalloc (last_basic_block - (INVALID_BLOCK + 1),
sizeof (regset));
/* Create a worklist. Allocate an extra slot for ENTRY_BLOCK, and one
because the `head == tail' style test for an empty queue doesn't
work with a full queue. */
queue = xmalloc ((n_basic_blocks - (INVALID_BLOCK + 1)) * sizeof (*queue));
qtail = queue;
qhead = qend = queue + n_basic_blocks - (INVALID_BLOCK + 1);
/* Queue the blocks set in the initial mask. Do this in reverse block
number order so that we are more likely for the first round to do
useful work. We use AUX non-null to flag that the block is queued. */
if (blocks_in)
{
FOR_EACH_BB (bb)
if (TEST_BIT (blocks_in, bb->index))
{
*--qhead = bb;
bb->aux = bb;
}
}
else
{
FOR_EACH_BB (bb)
{
*--qhead = bb;
bb->aux = bb;
}
}
block_accesses = xcalloc (last_basic_block, sizeof (int));
/* We clean aux when we remove the initially-enqueued bbs, but we
don't enqueue ENTRY and EXIT initially, so clean them upfront and
unconditionally. */
ENTRY_BLOCK_PTR->aux = EXIT_BLOCK_PTR->aux = NULL;
if (blocks_out)
sbitmap_zero (blocks_out);
/* We work through the queue until there are no more blocks. What
is live at the end of this block is precisely the union of what
is live at the beginning of all its successors. So, we set its
GLOBAL_LIVE_AT_END field based on the GLOBAL_LIVE_AT_START field
for its successors. Then, we compute GLOBAL_LIVE_AT_START for
this block by walking through the instructions in this block in
reverse order and updating as we go. If that changed
GLOBAL_LIVE_AT_START, we add the predecessors of the block to the
queue; they will now need to recalculate GLOBAL_LIVE_AT_END.
We are guaranteed to terminate, because GLOBAL_LIVE_AT_START
never shrinks. If a register appears in GLOBAL_LIVE_AT_START, it
must either be live at the end of the block, or used within the
block. In the latter case, it will certainly never disappear
from GLOBAL_LIVE_AT_START. In the former case, the register
could go away only if it disappeared from GLOBAL_LIVE_AT_START
for one of the successor blocks. By induction, that cannot
occur.
??? This reasoning doesn't work if we start from non-empty initial
GLOBAL_LIVE_AT_START sets. And there are actually two problems:
1) Updating may not terminate (endless oscillation).
2) Even if it does (and it usually does), the resulting information
may be inaccurate. Consider for example the following case:
a = ...;
while (...) {...} -- 'a' not mentioned at all
... = a;
If the use of 'a' is deleted between two calculations of liveness
information and the initial sets are not cleared, the information
about a's liveness will get stuck inside the loop and the set will
appear not to be dead.
We do not attempt to solve 2) -- the information is conservatively
correct (i.e. we never claim that something live is dead) and the
amount of optimization opportunities missed due to this problem is
not significant.
1) is more serious. In order to fix it, we monitor the number of times
each block is processed. Once one of the blocks has been processed more
times than the maximum number of rounds, we use the following strategy:
When a register disappears from one of the sets, we add it to a MAKE_DEAD
set, remove all registers in this set from all GLOBAL_LIVE_AT_* sets and
add the blocks with changed sets into the queue. Thus we are guaranteed
to terminate (the worst case corresponds to all registers in MADE_DEAD,
in which case the original reasoning above is valid), but in general we
only fix up a few offending registers.
The maximum number of rounds for computing liveness is the largest of
MAX_LIVENESS_ROUNDS and the latest loop depth count for this function. */
while (qhead != qtail)
{
int rescan, changed;
basic_block bb;
edge e;
edge_iterator ei;
bb = *qhead++;
if (qhead == qend)
qhead = queue;
bb->aux = NULL;
/* Should we start using the failure strategy? */
if (bb != ENTRY_BLOCK_PTR)
{
int max_liveness_rounds =
MAX (MAX_LIVENESS_ROUNDS, cfun->max_loop_depth);
block_accesses[bb->index]++;
if (block_accesses[bb->index] > max_liveness_rounds)
failure_strategy_required = true;
}
/* Begin by propagating live_at_start from the successor blocks. */
CLEAR_REG_SET (new_live_at_end);
if (EDGE_COUNT (bb->succs) > 0)
FOR_EACH_EDGE (e, ei, bb->succs)
{
basic_block sb = e->dest;
/* Call-clobbered registers die across exception and
call edges. */
/* ??? Abnormal call edges ignored for the moment, as this gets
confused by sibling call edges, which crashes reg-stack. */
if (e->flags & EDGE_EH)
bitmap_ior_and_compl_into (new_live_at_end,
sb->global_live_at_start,
invalidated_by_call);
else
IOR_REG_SET (new_live_at_end, sb->global_live_at_start);
/* If a target saves one register in another (instead of on
the stack) the save register will need to be live for EH. */
if (e->flags & EDGE_EH)
for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
if (EH_USES (i))
SET_REGNO_REG_SET (new_live_at_end, i);
}
else
{
/* This might be a noreturn function that throws. And
even if it isn't, getting the unwind info right helps
debugging. */
for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
if (EH_USES (i))
SET_REGNO_REG_SET (new_live_at_end, i);
}
/* The all-important stack pointer must always be live. */
SET_REGNO_REG_SET (new_live_at_end, STACK_POINTER_REGNUM);
/* Before reload, there are a few registers that must be forced
live everywhere -- which might not already be the case for
blocks within infinite loops. */
if (! reload_completed)
{
/* Any reference to any pseudo before reload is a potential
reference of the frame pointer. */
SET_REGNO_REG_SET (new_live_at_end, FRAME_POINTER_REGNUM);
#if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
/* Pseudos with argument area equivalences may require
reloading via the argument pointer. */
if (fixed_regs[ARG_POINTER_REGNUM])
SET_REGNO_REG_SET (new_live_at_end, ARG_POINTER_REGNUM);
#endif
/* Any constant, or pseudo with constant equivalences, may
require reloading from memory using the pic register. */
if ((unsigned) PIC_OFFSET_TABLE_REGNUM != INVALID_REGNUM
&& fixed_regs[PIC_OFFSET_TABLE_REGNUM])
SET_REGNO_REG_SET (new_live_at_end, PIC_OFFSET_TABLE_REGNUM);
}
if (bb == ENTRY_BLOCK_PTR)
{
COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
continue;
}
/* On our first pass through this block, we'll go ahead and continue.
Recognize first pass by checking if local_set is NULL for this
basic block. On subsequent passes, we get to skip out early if
live_at_end wouldn't have changed. */
if (local_sets[bb->index - (INVALID_BLOCK + 1)] == NULL)
{
local_sets[bb->index - (INVALID_BLOCK + 1)]
= ALLOC_REG_SET (&reg_obstack);
cond_local_sets[bb->index - (INVALID_BLOCK + 1)]
= ALLOC_REG_SET (&reg_obstack);
rescan = 1;
}
else
{
/* If any bits were removed from live_at_end, we'll have to
rescan the block. This wouldn't be necessary if we had
precalculated local_live, however with PROP_SCAN_DEAD_CODE
local_live is really dependent on live_at_end. */
rescan = bitmap_intersect_compl_p (bb->global_live_at_end,
new_live_at_end);
if (!rescan)
{
regset cond_local_set;
/* If any of the registers in the new live_at_end set are
conditionally set in this basic block, we must rescan.
This is because conditional lifetimes at the end of the
block do not just take the live_at_end set into
account, but also the liveness at the start of each
successor block. We can miss changes in those sets if
we only compare the new live_at_end against the
previous one. */
cond_local_set = cond_local_sets[bb->index - (INVALID_BLOCK + 1)];
rescan = bitmap_intersect_p (new_live_at_end, cond_local_set);
}
if (!rescan)
{
regset local_set;
/* Find the set of changed bits. Take this opportunity
to notice that this set is empty and early out. */
bitmap_xor (tmp, bb->global_live_at_end, new_live_at_end);
if (bitmap_empty_p (tmp))
continue;
/* If any of the changed bits overlap with local_sets[bb],
we'll have to rescan the block. */
local_set = local_sets[bb->index - (INVALID_BLOCK + 1)];
rescan = bitmap_intersect_p (tmp, local_set);
}
}
/* Let our caller know that BB changed enough to require its
death notes updated. */
if (blocks_out)
SET_BIT (blocks_out, bb->index);
if (! rescan)
{
/* Add to live_at_start the set of all registers in
new_live_at_end that aren't in the old live_at_end. */
changed = bitmap_ior_and_compl_into (bb->global_live_at_start,
new_live_at_end,
bb->global_live_at_end);
COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
if (! changed)
continue;
}
else
{
COPY_REG_SET (bb->global_live_at_end, new_live_at_end);
/* Rescan the block insn by insn to turn (a copy of) live_at_end
into live_at_start. */
propagate_block (bb, new_live_at_end,
local_sets[bb->index - (INVALID_BLOCK + 1)],
cond_local_sets[bb->index - (INVALID_BLOCK + 1)],
flags);
/* If live_at start didn't change, no need to go farther. */
if (REG_SET_EQUAL_P (bb->global_live_at_start, new_live_at_end))
continue;
if (failure_strategy_required)
{
/* Get the list of registers that were removed from the
bb->global_live_at_start set. */
bitmap_and_compl (tmp, bb->global_live_at_start,
new_live_at_end);
if (!bitmap_empty_p (tmp))
{
bool pbb_changed;
basic_block pbb;
/* It should not happen that one of registers we have
removed last time is disappears again before any other
register does. */
pbb_changed = bitmap_ior_into (registers_made_dead, tmp);
gcc_assert (pbb_changed);
/* Now remove the registers from all sets. */
FOR_EACH_BB (pbb)
{
pbb_changed = false;
pbb_changed
|= bitmap_and_compl_into (pbb->global_live_at_start,
registers_made_dead);
pbb_changed
|= bitmap_and_compl_into (pbb->global_live_at_end,
registers_made_dead);
if (!pbb_changed)
continue;
/* Note the (possible) change. */
if (blocks_out)
SET_BIT (blocks_out, pbb->index);
/* Makes sure to really rescan the block. */
if (local_sets[pbb->index - (INVALID_BLOCK + 1)])
{
FREE_REG_SET (local_sets[pbb->index - (INVALID_BLOCK + 1)]);
FREE_REG_SET (cond_local_sets[pbb->index - (INVALID_BLOCK + 1)]);
local_sets[pbb->index - (INVALID_BLOCK + 1)] = 0;
}
/* Add it to the queue. */
if (pbb->aux == NULL)
{
*qtail++ = pbb;
if (qtail == qend)
qtail = queue;
pbb->aux = pbb;
}
}
continue;
}
} /* end of failure_strategy_required */
COPY_REG_SET (bb->global_live_at_start, new_live_at_end);
}
/* Queue all predecessors of BB so that we may re-examine
their live_at_end. */
FOR_EACH_EDGE (e, ei, bb->preds)
{
basic_block pb = e->src;
if (pb->aux == NULL)
{
*qtail++ = pb;
if (qtail == qend)
qtail = queue;
pb->aux = pb;
}
}
}
FREE_REG_SET (tmp);
FREE_REG_SET (new_live_at_end);
FREE_REG_SET (invalidated_by_call);
FREE_REG_SET (registers_made_dead);
if (blocks_out)
{
EXECUTE_IF_SET_IN_SBITMAP (blocks_out, 0, i,
{
basic_block bb = BASIC_BLOCK (i);
FREE_REG_SET (local_sets[bb->index - (INVALID_BLOCK + 1)]);
FREE_REG_SET (cond_local_sets[bb->index - (INVALID_BLOCK + 1)]);
});
}
else
{
FOR_EACH_BB (bb)
{
FREE_REG_SET (local_sets[bb->index - (INVALID_BLOCK + 1)]);
FREE_REG_SET (cond_local_sets[bb->index - (INVALID_BLOCK + 1)]);
}
}
free (block_accesses);
free (queue);
free (cond_local_sets);
free (local_sets);
}
/* This structure is used to pass parameters to and from the
the function find_regno_partial(). It is used to pass in the
register number we are looking, as well as to return any rtx
we find. */
typedef struct {
unsigned regno_to_find;
rtx retval;
} find_regno_partial_param;
/* Find the rtx for the reg numbers specified in 'data' if it is
part of an expression which only uses part of the register. Return
it in the structure passed in. */
static int
find_regno_partial (rtx *ptr, void *data)
{
find_regno_partial_param *param = (find_regno_partial_param *)data;
unsigned reg = param->regno_to_find;
param->retval = NULL_RTX;
if (*ptr == NULL_RTX)
return 0;
switch (GET_CODE (*ptr))
{
case ZERO_EXTRACT:
case SIGN_EXTRACT:
case STRICT_LOW_PART:
if (REG_P (XEXP (*ptr, 0)) && REGNO (XEXP (*ptr, 0)) == reg)
{
param->retval = XEXP (*ptr, 0);
return 1;
}
break;
case SUBREG:
if (REG_P (SUBREG_REG (*ptr))
&& REGNO (SUBREG_REG (*ptr)) == reg)
{
param->retval = SUBREG_REG (*ptr);
return 1;
}
break;
default:
break;
}
return 0;
}
/* Process all immediate successors of the entry block looking for pseudo
registers which are live on entry. Find all of those whose first
instance is a partial register reference of some kind, and initialize
them to 0 after the entry block. This will prevent bit sets within
registers whose value is unknown, and may contain some kind of sticky
bits we don't want. */
int
initialize_uninitialized_subregs (void)
{
rtx insn;
edge e;
unsigned reg, did_something = 0;
find_regno_partial_param param;
edge_iterator ei;
/* APPLE LOCAL begin 4727273 */
/* This is needed for ia64, since a subreg operation does not guarantee
that the NaT bit will be cleared. A discussion of this can be found
here: http://gcc.gnu.org/ml/gcc-patches/2001-11/msg00429.html
For the architectures we support, this code isn't needed and can
generate superfluous code. */
#ifndef TARGET_MUST_INIT_SUBREG
return 0;
#endif
/* APPLE LOCAL end 4727273 */
FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
{
basic_block bb = e->dest;
regset map = bb->global_live_at_start;
reg_set_iterator rsi;
EXECUTE_IF_SET_IN_REG_SET (map, FIRST_PSEUDO_REGISTER, reg, rsi)
{
int uid = REGNO_FIRST_UID (reg);
rtx i;
/* Find an insn which mentions the register we are looking for.
Its preferable to have an instance of the register's rtl since
there may be various flags set which we need to duplicate.
If we can't find it, its probably an automatic whose initial
value doesn't matter, or hopefully something we don't care about. */
for (i = get_insns (); i && INSN_UID (i) != uid; i = NEXT_INSN (i))
;
if (i != NULL_RTX)
{
/* Found the insn, now get the REG rtx, if we can. */
param.regno_to_find = reg;
for_each_rtx (&i, find_regno_partial, &param);
if (param.retval != NULL_RTX)
{
start_sequence ();
emit_move_insn (param.retval,
CONST0_RTX (GET_MODE (param.retval)));
insn = get_insns ();
end_sequence ();
insert_insn_on_edge (insn, e);
did_something = 1;
}
}
}
}
if (did_something)
commit_edge_insertions ();
return did_something;
}
/* Subroutines of life analysis. */
/* Allocate the permanent data structures that represent the results
of life analysis. */
static void
allocate_bb_life_data (void)
{
basic_block bb;
FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
{
bb->global_live_at_start = ALLOC_REG_SET (&reg_obstack);
bb->global_live_at_end = ALLOC_REG_SET (&reg_obstack);
}
regs_live_at_setjmp = ALLOC_REG_SET (&reg_obstack);
}
void
allocate_reg_life_data (void)
{
int i;
max_regno = max_reg_num ();
gcc_assert (!reg_deaths);
reg_deaths = xcalloc (sizeof (*reg_deaths), max_regno);
/* Recalculate the register space, in case it has grown. Old style
vector oriented regsets would set regset_{size,bytes} here also. */
allocate_reg_info (max_regno, FALSE, FALSE);
/* Reset all the data we'll collect in propagate_block and its
subroutines. */
for (i = 0; i < max_regno; i++)
{
REG_N_SETS (i) = 0;
REG_N_REFS (i) = 0;
REG_N_DEATHS (i) = 0;
REG_N_CALLS_CROSSED (i) = 0;
REG_LIVE_LENGTH (i) = 0;
REG_FREQ (i) = 0;
REG_BASIC_BLOCK (i) = REG_BLOCK_UNKNOWN;
}
}
/* Delete dead instructions for propagate_block. */
static void
propagate_block_delete_insn (rtx insn)
{
rtx inote = find_reg_note (insn, REG_LABEL, NULL_RTX);
/* If the insn referred to a label, and that label was attached to
an ADDR_VEC, it's safe to delete the ADDR_VEC. In fact, it's
pretty much mandatory to delete it, because the ADDR_VEC may be
referencing labels that no longer exist.
INSN may reference a deleted label, particularly when a jump
table has been optimized into a direct jump. There's no
real good way to fix up the reference to the deleted label
when the label is deleted, so we just allow it here. */
if (inote && LABEL_P (inote))
{
rtx label = XEXP (inote, 0);
rtx next;
/* The label may be forced if it has been put in the constant
pool. If that is the only use we must discard the table
jump following it, but not the label itself. */
if (LABEL_NUSES (label) == 1 + LABEL_PRESERVE_P (label)
&& (next = next_nonnote_insn (label)) != NULL
&& JUMP_P (next)
&& (GET_CODE (PATTERN (next)) == ADDR_VEC
|| GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
{
rtx pat = PATTERN (next);
int diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
int len = XVECLEN (pat, diff_vec_p);
int i;
for (i = 0; i < len; i++)
LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0))--;
delete_insn_and_edges (next);
ndead++;
}
}
delete_insn_and_edges (insn);
ndead++;
}
/* Delete dead libcalls for propagate_block. Return the insn
before the libcall. */
static rtx
propagate_block_delete_libcall (rtx insn, rtx note)
{
rtx first = XEXP (note, 0);
rtx before = PREV_INSN (first);
delete_insn_chain_and_edges (first, insn);
ndead++;
return before;
}
/* Update the life-status of regs for one insn. Return the previous insn. */
rtx
propagate_one_insn (struct propagate_block_info *pbi, rtx insn)
{
rtx prev = PREV_INSN (insn);
int flags = pbi->flags;
int insn_is_dead = 0;
int libcall_is_dead = 0;
rtx note;
unsigned i;
if (! INSN_P (insn))
return prev;
note = find_reg_note (insn, REG_RETVAL, NULL_RTX);
if (flags & PROP_SCAN_DEAD_CODE)
{
insn_is_dead = insn_dead_p (pbi, PATTERN (insn), 0, REG_NOTES (insn));
libcall_is_dead = (insn_is_dead && note != 0
&& libcall_dead_p (pbi, note, insn));
}
/* If an instruction consists of just dead store(s) on final pass,
delete it. */
if ((flags & PROP_KILL_DEAD_CODE) && insn_is_dead)
{
/* If we're trying to delete a prologue or epilogue instruction
that isn't flagged as possibly being dead, something is wrong.
But if we are keeping the stack pointer depressed, we might well
be deleting insns that are used to compute the amount to update
it by, so they are fine. */
if (reload_completed
&& !(TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
&& (TYPE_RETURNS_STACK_DEPRESSED
(TREE_TYPE (current_function_decl))))
&& (((HAVE_epilogue || HAVE_prologue)
&& prologue_epilogue_contains (insn))
|| (HAVE_sibcall_epilogue
&& sibcall_epilogue_contains (insn)))
&& find_reg_note (insn, REG_MAYBE_DEAD, NULL_RTX) == 0)
fatal_insn ("Attempt to delete prologue/epilogue insn:", insn);
/* Record sets. Do this even for dead instructions, since they
would have killed the values if they hadn't been deleted. */
mark_set_regs (pbi, PATTERN (insn), insn);
/* CC0 is now known to be dead. Either this insn used it,
in which case it doesn't anymore, or clobbered it,
so the next insn can't use it. */
pbi->cc0_live = 0;
if (libcall_is_dead)
prev = propagate_block_delete_libcall (insn, note);
else
{
/* If INSN contains a RETVAL note and is dead, but the libcall
as a whole is not dead, then we want to remove INSN, but
not the whole libcall sequence.
However, we need to also remove the dangling REG_LIBCALL
note so that we do not have mis-matched LIBCALL/RETVAL
notes. In theory we could find a new location for the
REG_RETVAL note, but it hardly seems worth the effort.
NOTE at this point will be the RETVAL note if it exists. */
if (note)
{
rtx libcall_note;
libcall_note
= find_reg_note (XEXP (note, 0), REG_LIBCALL, NULL_RTX);
remove_note (XEXP (note, 0), libcall_note);
}
/* Similarly if INSN contains a LIBCALL note, remove the
dangling REG_RETVAL note. */
note = find_reg_note (insn, REG_LIBCALL, NULL_RTX);
if (note)
{
rtx retval_note;
retval_note
= find_reg_note (XEXP (note, 0), REG_RETVAL, NULL_RTX);
remove_note (XEXP (note, 0), retval_note);
}
/* Now delete INSN. */
propagate_block_delete_insn (insn);
}
return prev;
}
/* See if this is an increment or decrement that can be merged into
a following memory address. */
#ifdef AUTO_INC_DEC
{
rtx x = single_set (insn);
/* Does this instruction increment or decrement a register? */
if ((flags & PROP_AUTOINC)
&& x != 0
&& REG_P (SET_DEST (x))
&& (GET_CODE (SET_SRC (x)) == PLUS
|| GET_CODE (SET_SRC (x)) == MINUS)
&& XEXP (SET_SRC (x), 0) == SET_DEST (x)
&& GET_CODE (XEXP (SET_SRC (x), 1)) == CONST_INT
/* Ok, look for a following memory ref we can combine with.
If one is found, change the memory ref to a PRE_INC
or PRE_DEC, cancel this insn, and return 1.
Return 0 if nothing has been done. */
&& try_pre_increment_1 (pbi, insn))
return prev;
}
#endif /* AUTO_INC_DEC */
CLEAR_REG_SET (pbi->new_set);
/* If this is not the final pass, and this insn is copying the value of
a library call and it's dead, don't scan the insns that perform the
library call, so that the call's arguments are not marked live. */
if (libcall_is_dead)
{
/* Record the death of the dest reg. */
mark_set_regs (pbi, PATTERN (insn), insn);
insn = XEXP (note, 0);
return PREV_INSN (insn);
}
else if (GET_CODE (PATTERN (insn)) == SET
&& SET_DEST (PATTERN (insn)) == stack_pointer_rtx
&& GET_CODE (SET_SRC (PATTERN (insn))) == PLUS
&& XEXP (SET_SRC (PATTERN (insn)), 0) == stack_pointer_rtx
&& GET_CODE (XEXP (SET_SRC (PATTERN (insn)), 1)) == CONST_INT)
{
/* We have an insn to pop a constant amount off the stack.
(Such insns use PLUS regardless of the direction of the stack,
and any insn to adjust the stack by a constant is always a pop
or part of a push.)
These insns, if not dead stores, have no effect on life, though
they do have an effect on the memory stores we are tracking. */
invalidate_mems_from_set (pbi, stack_pointer_rtx);
/* Still, we need to update local_set, lest ifcvt.c:dead_or_predicable
concludes that the stack pointer is not modified. */
mark_set_regs (pbi, PATTERN (insn), insn);
}
else
{
rtx note;
/* Any regs live at the time of a call instruction must not go
in a register clobbered by calls. Find all regs now live and
record this for them. */
if (CALL_P (insn) && (flags & PROP_REG_INFO))
{
reg_set_iterator rsi;
EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i, rsi)
REG_N_CALLS_CROSSED (i)++;
}
/* Record sets. Do this even for dead instructions, since they
would have killed the values if they hadn't been deleted. */
mark_set_regs (pbi, PATTERN (insn), insn);
if (CALL_P (insn))
{
regset live_at_end;
bool sibcall_p;
rtx note, cond;
int i;
cond = NULL_RTX;
if (GET_CODE (PATTERN (insn)) == COND_EXEC)
cond = COND_EXEC_TEST (PATTERN (insn));
/* Non-constant calls clobber memory, constant calls do not
clobber memory, though they may clobber outgoing arguments
on the stack. */
if (! CONST_OR_PURE_CALL_P (insn))
{
free_EXPR_LIST_list (&pbi->mem_set_list);
pbi->mem_set_list_len = 0;
}
else
invalidate_mems_from_set (pbi, stack_pointer_rtx);
/* There may be extra registers to be clobbered. */
for (note = CALL_INSN_FUNCTION_USAGE (insn);
note;
note = XEXP (note, 1))
if (GET_CODE (XEXP (note, 0)) == CLOBBER)
mark_set_1 (pbi, CLOBBER, XEXP (XEXP (note, 0), 0),
cond, insn, pbi->flags);
/* Calls change all call-used and global registers; sibcalls do not
clobber anything that must be preserved at end-of-function,
except for return values. */
sibcall_p = SIBLING_CALL_P (insn);
live_at_end = EXIT_BLOCK_PTR->global_live_at_start;
for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
if (TEST_HARD_REG_BIT (regs_invalidated_by_call, i)
&& ! (sibcall_p
&& REGNO_REG_SET_P (live_at_end, i)
&& ! refers_to_regno_p (i, i+1,
current_function_return_rtx,
(rtx *) 0)))
{
enum rtx_code code = global_regs[i] ? SET : CLOBBER;
/* We do not want REG_UNUSED notes for these registers. */
mark_set_1 (pbi, code, regno_reg_rtx[i], cond, insn,
pbi->flags & ~(PROP_DEATH_NOTES | PROP_REG_INFO));
}
}
/* If an insn doesn't use CC0, it becomes dead since we assume
that every insn clobbers it. So show it dead here;
mark_used_regs will set it live if it is referenced. */
pbi->cc0_live = 0;
/* Record uses. */
if (! insn_is_dead)
mark_used_regs (pbi, PATTERN (insn), NULL_RTX, insn);
if ((flags & PROP_EQUAL_NOTES)
&& ((note = find_reg_note (insn, REG_EQUAL, NULL_RTX))
|| (note = find_reg_note (insn, REG_EQUIV, NULL_RTX))))
mark_used_regs (pbi, XEXP (note, 0), NULL_RTX, insn);
/* Sometimes we may have inserted something before INSN (such as a move)
when we make an auto-inc. So ensure we will scan those insns. */
#ifdef AUTO_INC_DEC
prev = PREV_INSN (insn);
#endif
if (! insn_is_dead && CALL_P (insn))
{
int i;
rtx note, cond;
cond = NULL_RTX;
if (GET_CODE (PATTERN (insn)) == COND_EXEC)
cond = COND_EXEC_TEST (PATTERN (insn));
/* Calls use their arguments, and may clobber memory which
address involves some register. */
for (note = CALL_INSN_FUNCTION_USAGE (insn);
note;
note = XEXP (note, 1))
/* We find USE or CLOBBER entities in a FUNCTION_USAGE list: both
of which mark_used_regs knows how to handle. */
mark_used_regs (pbi, XEXP (XEXP (note, 0), 0), cond, insn);
/* The stack ptr is used (honorarily) by a CALL insn. */
if ((flags & PROP_REG_INFO)
&& !REGNO_REG_SET_P (pbi->reg_live, STACK_POINTER_REGNUM))
reg_deaths[STACK_POINTER_REGNUM] = pbi->insn_num;
SET_REGNO_REG_SET (pbi->reg_live, STACK_POINTER_REGNUM);
/* Calls may also reference any of the global registers,
so they are made live. */
for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
if (global_regs[i])
mark_used_reg (pbi, regno_reg_rtx[i], cond, insn);
}
}
pbi->insn_num++;
return prev;
}
/* Initialize a propagate_block_info struct for public consumption.
Note that the structure itself is opaque to this file, but that
the user can use the regsets provided here. */
struct propagate_block_info *
init_propagate_block_info (basic_block bb, regset live, regset local_set,
regset cond_local_set, int flags)
{
struct propagate_block_info *pbi = xmalloc (sizeof (*pbi));
pbi->bb = bb;
pbi->reg_live = live;
pbi->mem_set_list = NULL_RTX;
pbi->mem_set_list_len = 0;
pbi->local_set = local_set;
pbi->cond_local_set = cond_local_set;
pbi->cc0_live = 0;
pbi->flags = flags;
pbi->insn_num = 0;
if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
pbi->reg_next_use = xcalloc (max_reg_num (), sizeof (rtx));
else
pbi->reg_next_use = NULL;
pbi->new_set = BITMAP_ALLOC (NULL);
#ifdef HAVE_conditional_execution
pbi->reg_cond_dead = splay_tree_new (splay_tree_compare_ints, NULL,
free_reg_cond_life_info);
pbi->reg_cond_reg = BITMAP_ALLOC (NULL);
/* If this block ends in a conditional branch, for each register
live from one side of the branch and not the other, record the
register as conditionally dead. */
if (JUMP_P (BB_END (bb))
&& any_condjump_p (BB_END (bb)))
{
regset diff = ALLOC_REG_SET (&reg_obstack);
basic_block bb_true, bb_false;
unsigned i;
/* Identify the successor blocks. */
bb_true = EDGE_SUCC (bb, 0)->dest;
if (EDGE_COUNT (bb->succs) > 1)
{
bb_false = EDGE_SUCC (bb, 1)->dest;
if (EDGE_SUCC (bb, 0)->flags & EDGE_FALLTHRU)
{
basic_block t = bb_false;
bb_false = bb_true;
bb_true = t;
}
else
gcc_assert (EDGE_SUCC (bb, 1)->flags & EDGE_FALLTHRU);
}
else
{
/* This can happen with a conditional jump to the next insn. */
gcc_assert (JUMP_LABEL (BB_END (bb)) == BB_HEAD (bb_true));
/* Simplest way to do nothing. */
bb_false = bb_true;
}
/* Compute which register lead different lives in the successors. */
bitmap_xor (diff, bb_true->global_live_at_start,
bb_false->global_live_at_start);
if (!bitmap_empty_p (diff))
{
/* Extract the condition from the branch. */
rtx set_src = SET_SRC (pc_set (BB_END (bb)));
rtx cond_true = XEXP (set_src, 0);
rtx reg = XEXP (cond_true, 0);
enum rtx_code inv_cond;
if (GET_CODE (reg) == SUBREG)
reg = SUBREG_REG (reg);
/* We can only track conditional lifetimes if the condition is
in the form of a reversible comparison of a register against
zero. If the condition is more complex than that, then it is
safe not to record any information. */
inv_cond = reversed_comparison_code (cond_true, BB_END (bb));
if (inv_cond != UNKNOWN
&& REG_P (reg)
&& XEXP (cond_true, 1) == const0_rtx)
{
rtx cond_false
= gen_rtx_fmt_ee (inv_cond,
GET_MODE (cond_true), XEXP (cond_true, 0),
XEXP (cond_true, 1));
reg_set_iterator rsi;
if (GET_CODE (XEXP (set_src, 1)) == PC)
{
rtx t = cond_false;
cond_false = cond_true;
cond_true = t;
}
SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (reg));
/* For each such register, mark it conditionally dead. */
EXECUTE_IF_SET_IN_REG_SET (diff, 0, i, rsi)
{
struct reg_cond_life_info *rcli;
rtx cond;
rcli = xmalloc (sizeof (*rcli));
if (REGNO_REG_SET_P (bb_true->global_live_at_start, i))
cond = cond_false;
else
cond = cond_true;
rcli->condition = cond;
rcli->stores = const0_rtx;
rcli->orig_condition = cond;
splay_tree_insert (pbi->reg_cond_dead, i,
(splay_tree_value) rcli);
}
}
}
FREE_REG_SET (diff);
}
#endif
/* If this block has no successors, any stores to the frame that aren't
used later in the block are dead. So make a pass over the block
recording any such that are made and show them dead at the end. We do
a very conservative and simple job here. */
if (optimize
&& ! (TREE_CODE (TREE_TYPE (current_function_decl)) == FUNCTION_TYPE
&& (TYPE_RETURNS_STACK_DEPRESSED
(TREE_TYPE (current_function_decl))))
&& (flags & PROP_SCAN_DEAD_STORES)
&& (EDGE_COUNT (bb->succs) == 0
|| (EDGE_COUNT (bb->succs) == 1
&& EDGE_SUCC (bb, 0)->dest == EXIT_BLOCK_PTR
&& ! current_function_calls_eh_return)))
{
rtx insn, set;
for (insn = BB_END (bb); insn != BB_HEAD (bb); insn = PREV_INSN (insn))
if (NONJUMP_INSN_P (insn)
&& (set = single_set (insn))
&& MEM_P (SET_DEST (set)))
{
rtx mem = SET_DEST (set);
rtx canon_mem = canon_rtx (mem);
if (XEXP (canon_mem, 0) == frame_pointer_rtx
|| (GET_CODE (XEXP (canon_mem, 0)) == PLUS
&& XEXP (XEXP (canon_mem, 0), 0) == frame_pointer_rtx
&& GET_CODE (XEXP (XEXP (canon_mem, 0), 1)) == CONST_INT))
add_to_mem_set_list (pbi, canon_mem);
}
}
return pbi;
}
/* Release a propagate_block_info struct. */
void
free_propagate_block_info (struct propagate_block_info *pbi)
{
free_EXPR_LIST_list (&pbi->mem_set_list);
BITMAP_FREE (pbi->new_set);
#ifdef HAVE_conditional_execution
splay_tree_delete (pbi->reg_cond_dead);
BITMAP_FREE (pbi->reg_cond_reg);
#endif
if (pbi->flags & PROP_REG_INFO)
{
int num = pbi->insn_num;
unsigned i;
reg_set_iterator rsi;
EXECUTE_IF_SET_IN_REG_SET (pbi->reg_live, 0, i, rsi)
{
REG_LIVE_LENGTH (i) += num - reg_deaths[i];
reg_deaths[i] = 0;
}
}
if (pbi->reg_next_use)
free (pbi->reg_next_use);
free (pbi);
}
/* Compute the registers live at the beginning of a basic block BB from
those live at the end.
When called, REG_LIVE contains those live at the end. On return, it
contains those live at the beginning.
LOCAL_SET, if non-null, will be set with all registers killed
unconditionally by this basic block.
Likewise, COND_LOCAL_SET, if non-null, will be set with all registers
killed conditionally by this basic block. If there is any unconditional
set of a register, then the corresponding bit will be set in LOCAL_SET
and cleared in COND_LOCAL_SET.
It is valid for LOCAL_SET and COND_LOCAL_SET to be the same set. In this
case, the resulting set will be equal to the union of the two sets that
would otherwise be computed.
Return nonzero if an INSN is deleted (i.e. by dead code removal). */
int
propagate_block (basic_block bb, regset live, regset local_set,
regset cond_local_set, int flags)
{
struct propagate_block_info *pbi;
rtx insn, prev;
int changed;
pbi = init_propagate_block_info (bb, live, local_set, cond_local_set, flags);
if (flags & PROP_REG_INFO)
{
unsigned i;
reg_set_iterator rsi;
/* Process the regs live at the end of the block.
Mark them as not local to any one basic block. */
EXECUTE_IF_SET_IN_REG_SET (live, 0, i, rsi)
REG_BASIC_BLOCK (i) = REG_BLOCK_GLOBAL;
}
/* Scan the block an insn at a time from end to beginning. */
changed = 0;
for (insn = BB_END (bb); ; insn = prev)
{
/* If this is a call to `setjmp' et al, warn if any
non-volatile datum is live. */
if ((flags & PROP_REG_INFO)
&& CALL_P (insn)
&& find_reg_note (insn, REG_SETJMP, NULL))
IOR_REG_SET (regs_live_at_setjmp, pbi->reg_live);
prev = propagate_one_insn (pbi, insn);
if (!prev)
changed |= insn != get_insns ();
else
changed |= NEXT_INSN (prev) != insn;
if (insn == BB_HEAD (bb))
break;
}
free_propagate_block_info (pbi);
return changed;
}
/* Return 1 if X (the body of an insn, or part of it) is just dead stores
(SET expressions whose destinations are registers dead after the insn).
NEEDED is the regset that says which regs are alive after the insn.
Unless CALL_OK is nonzero, an insn is needed if it contains a CALL.
If X is the entire body of an insn, NOTES contains the reg notes
pertaining to the insn. */
static int
insn_dead_p (struct propagate_block_info *pbi, rtx x, int call_ok,
rtx notes ATTRIBUTE_UNUSED)
{
enum rtx_code code = GET_CODE (x);
/* Don't eliminate insns that may trap. */
if (flag_non_call_exceptions && may_trap_p (x))
return 0;
#ifdef AUTO_INC_DEC
/* As flow is invoked after combine, we must take existing AUTO_INC
expressions into account. */
for (; notes; notes = XEXP (notes, 1))
{
if (REG_NOTE_KIND (notes) == REG_INC)
{
int regno = REGNO (XEXP (notes, 0));
/* Don't delete insns to set global regs. */
if ((regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
|| REGNO_REG_SET_P (pbi->reg_live, regno))
return 0;
}
}
#endif
/* If setting something that's a reg or part of one,
see if that register's altered value will be live. */
if (code == SET)
{
rtx r = SET_DEST (x);
#ifdef HAVE_cc0
if (GET_CODE (r) == CC0)
return ! pbi->cc0_live;
#endif
/* A SET that is a subroutine call cannot be dead. */
if (GET_CODE (SET_SRC (x)) == CALL)
{
if (! call_ok)
return 0;
}
/* Don't eliminate loads from volatile memory or volatile asms. */
else if (volatile_refs_p (SET_SRC (x)))
return 0;
if (MEM_P (r))
{
rtx temp, canon_r;
if (MEM_VOLATILE_P (r) || GET_MODE (r) == BLKmode)
return 0;
canon_r = canon_rtx (r);
/* Walk the set of memory locations we are currently tracking
and see if one is an identical match to this memory location.
If so, this memory write is dead (remember, we're walking
backwards from the end of the block to the start). Since
rtx_equal_p does not check the alias set or flags, we also
must have the potential for them to conflict (anti_dependence). */
for (temp = pbi->mem_set_list; temp != 0; temp = XEXP (temp, 1))
if (anti_dependence (r, XEXP (temp, 0)))
{
rtx mem = XEXP (temp, 0);
if (rtx_equal_p (XEXP (canon_r, 0), XEXP (mem, 0))
&& (GET_MODE_SIZE (GET_MODE (canon_r))
<= GET_MODE_SIZE (GET_MODE (mem))))
return 1;
#ifdef AUTO_INC_DEC
/* Check if memory reference matches an auto increment. Only
post increment/decrement or modify are valid. */
if (GET_MODE (mem) == GET_MODE (r)
&& (GET_CODE (XEXP (mem, 0)) == POST_DEC
|| GET_CODE (XEXP (mem, 0)) == POST_INC
|| GET_CODE (XEXP (mem, 0)) == POST_MODIFY)
&& GET_MODE (XEXP (mem, 0)) == GET_MODE (r)
&& rtx_equal_p (XEXP (XEXP (mem, 0), 0), XEXP (r, 0)))
return 1;
#endif
}
}
else
{
while (GET_CODE (r) == SUBREG
|| GET_CODE (r) == STRICT_LOW_PART
|| GET_CODE (r) == ZERO_EXTRACT)
r = XEXP (r, 0);
if (REG_P (r))
{
int regno = REGNO (r);
/* Obvious. */
if (REGNO_REG_SET_P (pbi->reg_live, regno))
return 0;
/* If this is a hard register, verify that subsequent
words are not needed. */
if (regno < FIRST_PSEUDO_REGISTER)
{
int n = hard_regno_nregs[regno][GET_MODE (r)];
while (--n > 0)
if (REGNO_REG_SET_P (pbi->reg_live, regno+n))
return 0;
}
/* Don't delete insns to set global regs. */
if (regno < FIRST_PSEUDO_REGISTER && global_regs[regno])
return 0;
/* Make sure insns to set the stack pointer aren't deleted. */
if (regno == STACK_POINTER_REGNUM)
return 0;
/* ??? These bits might be redundant with the force live bits
in calculate_global_regs_live. We would delete from
sequential sets; whether this actually affects real code
for anything but the stack pointer I don't know. */
/* Make sure insns to set the frame pointer aren't deleted. */
if (regno == FRAME_POINTER_REGNUM
&& (! reload_completed || frame_pointer_needed))
return 0;
#if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
if (regno == HARD_FRAME_POINTER_REGNUM
&& (! reload_completed || frame_pointer_needed))
return 0;
#endif
#if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
/* Make sure insns to set arg pointer are never deleted
(if the arg pointer isn't fixed, there will be a USE
for it, so we can treat it normally). */
if (regno == ARG_POINTER_REGNUM && fixed_regs[regno])
return 0;
#endif
/* Otherwise, the set is dead. */
return 1;
}
}
}
/* If performing several activities, insn is dead if each activity
is individually dead. Also, CLOBBERs and USEs can be ignored; a
CLOBBER or USE that's inside a PARALLEL doesn't make the insn
worth keeping. */
else if (code == PARALLEL)
{
int i = XVECLEN (x, 0);
for (i--; i >= 0; i--)
if (GET_CODE (XVECEXP (x, 0, i)) != CLOBBER
&& GET_CODE (XVECEXP (x, 0, i)) != USE
&& ! insn_dead_p (pbi, XVECEXP (x, 0, i), call_ok, NULL_RTX))
return 0;
return 1;
}
/* A CLOBBER of a pseudo-register that is dead serves no purpose. That
is not necessarily true for hard registers until after reload. */
else if (code == CLOBBER)
{
if (REG_P (XEXP (x, 0))
&& (REGNO (XEXP (x, 0)) >= FIRST_PSEUDO_REGISTER
|| reload_completed)
&& ! REGNO_REG_SET_P (pbi->reg_live, REGNO (XEXP (x, 0))))
return 1;
}
/* ??? A base USE is a historical relic. It ought not be needed anymore.
Instances where it is still used are either (1) temporary and the USE
escaped the pass, (2) cruft and the USE need not be emitted anymore,
or (3) hiding bugs elsewhere that are not properly representing data
flow. */
return 0;
}
/* If INSN is the last insn in a libcall, and assuming INSN is dead,
return 1 if the entire library call is dead.
This is true if INSN copies a register (hard or pseudo)
and if the hard return reg of the call insn is dead.
(The caller should have tested the destination of the SET inside
INSN already for death.)
If this insn doesn't just copy a register, then we don't
have an ordinary libcall. In that case, cse could not have
managed to substitute the source for the dest later on,
so we can assume the libcall is dead.
PBI is the block info giving pseudoregs live before this insn.
NOTE is the REG_RETVAL note of the insn. */
static int
libcall_dead_p (struct propagate_block_info *pbi, rtx note, rtx insn)
{
rtx x = single_set (insn);
if (x)
{
rtx r = SET_SRC (x);
if (REG_P (r) || GET_CODE (r) == SUBREG)
{
rtx call = XEXP (note, 0);
rtx call_pat;
int i;
/* Find the call insn. */
while (call != insn && !CALL_P (call))
call = NEXT_INSN (call);
/* If there is none, do nothing special,
since ordinary death handling can understand these insns. */
if (call == insn)
return 0;
/* See if the hard reg holding the value is dead.
If this is a PARALLEL, find the call within it. */
call_pat = PATTERN (call);
if (GET_CODE (call_pat) == PARALLEL)
{
for (i = XVECLEN (call_pat, 0) - 1; i >= 0; i--)
if (GET_CODE (XVECEXP (call_pat, 0, i)) == SET
&& GET_CODE (SET_SRC (XVECEXP (call_pat, 0, i))) == CALL)
break;
/* This may be a library call that is returning a value
via invisible pointer. Do nothing special, since
ordinary death handling can understand these insns. */
if (i < 0)
return 0;
call_pat = XVECEXP (call_pat, 0, i);
}
if (! insn_dead_p (pbi, call_pat, 1, REG_NOTES (call)))
return 0;
while ((insn = PREV_INSN (insn)) != call)
{
if (! INSN_P (insn))
continue;
if (! insn_dead_p (pbi, PATTERN (insn), 0, REG_NOTES (insn)))
return 0;
}
return 1;
}
}
return 0;
}
/* 1 if register REGNO was alive at a place where `setjmp' was called
and was set more than once or is an argument.
Such regs may be clobbered by `longjmp'. */
int
regno_clobbered_at_setjmp (int regno)
{
if (n_basic_blocks == 0)
return 0;
return ((REG_N_SETS (regno) > 1
|| REGNO_REG_SET_P (ENTRY_BLOCK_PTR->global_live_at_end, regno))
&& REGNO_REG_SET_P (regs_live_at_setjmp, regno));
}
/* Add MEM to PBI->MEM_SET_LIST. MEM should be canonical. Respect the
maximal list size; look for overlaps in mode and select the largest. */
static void
add_to_mem_set_list (struct propagate_block_info *pbi, rtx mem)
{
rtx i;
/* We don't know how large a BLKmode store is, so we must not
take them into consideration. */
if (GET_MODE (mem) == BLKmode)
return;
for (i = pbi->mem_set_list; i ; i = XEXP (i, 1))
{
rtx e = XEXP (i, 0);
if (rtx_equal_p (XEXP (mem, 0), XEXP (e, 0)))
{
if (GET_MODE_SIZE (GET_MODE (mem)) > GET_MODE_SIZE (GET_MODE (e)))
{
#ifdef AUTO_INC_DEC
/* If we must store a copy of the mem, we can just modify
the mode of the stored copy. */
if (pbi->flags & PROP_AUTOINC)
PUT_MODE (e, GET_MODE (mem));
else
#endif
XEXP (i, 0) = mem;
}
return;
}
}
if (pbi->mem_set_list_len < MAX_MEM_SET_LIST_LEN)
{
#ifdef AUTO_INC_DEC
/* Store a copy of mem, otherwise the address may be
scrogged by find_auto_inc. */
if (pbi->flags & PROP_AUTOINC)
mem = shallow_copy_rtx (mem);
#endif
pbi->mem_set_list = alloc_EXPR_LIST (0, mem, pbi->mem_set_list);
pbi->mem_set_list_len++;
}
}
/* INSN references memory, possibly using autoincrement addressing modes.
Find any entries on the mem_set_list that need to be invalidated due
to an address change. */
static int
invalidate_mems_from_autoinc (rtx *px, void *data)
{
rtx x = *px;
struct propagate_block_info *pbi = data;
if (GET_RTX_CLASS (GET_CODE (x)) == RTX_AUTOINC)
{
invalidate_mems_from_set (pbi, XEXP (x, 0));
return -1;
}
return 0;
}
/* EXP is a REG. Remove any dependent entries from pbi->mem_set_list. */
static void
invalidate_mems_from_set (struct propagate_block_info *pbi, rtx exp)
{
rtx temp = pbi->mem_set_list;
rtx prev = NULL_RTX;
rtx next;
while (temp)
{
next = XEXP (temp, 1);
if (reg_overlap_mentioned_p (exp, XEXP (temp, 0)))
{
/* Splice this entry out of the list. */
if (prev)
XEXP (prev, 1) = next;
else
pbi->mem_set_list = next;
free_EXPR_LIST_node (temp);
pbi->mem_set_list_len--;
}
else
prev = temp;
temp = next;
}
}
/* Process the registers that are set within X. Their bits are set to
1 in the regset DEAD, because they are dead prior to this insn.
If INSN is nonzero, it is the insn being processed.
FLAGS is the set of operations to perform. */
static void
mark_set_regs (struct propagate_block_info *pbi, rtx x, rtx insn)
{
rtx cond = NULL_RTX;
rtx link;
enum rtx_code code;
int flags = pbi->flags;
if (insn)
for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
{
if (REG_NOTE_KIND (link) == REG_INC)
mark_set_1 (pbi, SET, XEXP (link, 0),
(GET_CODE (x) == COND_EXEC
? COND_EXEC_TEST (x) : NULL_RTX),
insn, flags);
}
retry:
switch (code = GET_CODE (x))
{
case SET:
if (GET_CODE (XEXP (x, 1)) == ASM_OPERANDS)
flags |= PROP_ASM_SCAN;
/* Fall through */
case CLOBBER:
mark_set_1 (pbi, code, SET_DEST (x), cond, insn, flags);
return;
case COND_EXEC:
cond = COND_EXEC_TEST (x);
x = COND_EXEC_CODE (x);
goto retry;
case PARALLEL:
{
int i;
/* We must scan forwards. If we have an asm, we need to set
the PROP_ASM_SCAN flag before scanning the clobbers. */
for (i = 0; i < XVECLEN (x, 0); i++)
{
rtx sub = XVECEXP (x, 0, i);
switch (code = GET_CODE (sub))
{
case COND_EXEC:
gcc_assert (!cond);
cond = COND_EXEC_TEST (sub);
sub = COND_EXEC_CODE (sub);
if (GET_CODE (sub) == SET)
goto mark_set;
if (GET_CODE (sub) == CLOBBER)
goto mark_clob;
break;
case SET:
mark_set:
if (GET_CODE (XEXP (sub, 1)) == ASM_OPERANDS)
flags |= PROP_ASM_SCAN;
/* Fall through */
case CLOBBER:
mark_clob:
mark_set_1 (pbi, code, SET_DEST (sub), cond, insn, flags);
break;
case ASM_OPERANDS:
flags |= PROP_ASM_SCAN;
break;
default:
break;
}
}
break;
}
default:
break;
}
}
/* Process a single set, which appears in INSN. REG (which may not
actually be a REG, it may also be a SUBREG, PARALLEL, etc.) is
being set using the CODE (which may be SET, CLOBBER, or COND_EXEC).
If the set is conditional (because it appear in a COND_EXEC), COND
will be the condition. */
static void
mark_set_1 (struct propagate_block_info *pbi, enum rtx_code code, rtx reg, rtx cond, rtx insn, int flags)
{
int regno_first = -1, regno_last = -1;
unsigned long not_dead = 0;
int i;
/* Modifying just one hardware register of a multi-reg value or just a
byte field of a register does not mean the value from before this insn
is now dead. Of course, if it was dead after it's unused now. */
switch (GET_CODE (reg))
{
case PARALLEL:
/* Some targets place small structures in registers for return values of
functions. We have to detect this case specially here to get correct
flow information. */
for (i = XVECLEN (reg, 0) - 1; i >= 0; i--)
if (XEXP (XVECEXP (reg, 0, i), 0) != 0)
mark_set_1 (pbi, code, XEXP (XVECEXP (reg, 0, i), 0), cond, insn,
flags);
return;
case SIGN_EXTRACT:
/* SIGN_EXTRACT cannot be an lvalue. */
gcc_unreachable ();
case ZERO_EXTRACT:
case STRICT_LOW_PART:
/* ??? Assumes STRICT_LOW_PART not used on multi-word registers. */
do
reg = XEXP (reg, 0);
while (GET_CODE (reg) == SUBREG
|| GET_CODE (reg) == ZERO_EXTRACT
|| GET_CODE (reg) == STRICT_LOW_PART);
if (MEM_P (reg))
break;
not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live, REGNO (reg));
/* Fall through. */
case REG:
regno_last = regno_first = REGNO (reg);
if (regno_first < FIRST_PSEUDO_REGISTER)
regno_last += hard_regno_nregs[regno_first][GET_MODE (reg)] - 1;
break;
case SUBREG:
if (REG_P (SUBREG_REG (reg)))
{
enum machine_mode outer_mode = GET_MODE (reg);
enum machine_mode inner_mode = GET_MODE (SUBREG_REG (reg));
/* Identify the range of registers affected. This is moderately
tricky for hard registers. See alter_subreg. */
regno_last = regno_first = REGNO (SUBREG_REG (reg));
if (regno_first < FIRST_PSEUDO_REGISTER)
{
regno_first += subreg_regno_offset (regno_first, inner_mode,
SUBREG_BYTE (reg),
outer_mode);
regno_last = (regno_first
+ hard_regno_nregs[regno_first][outer_mode] - 1);
/* Since we've just adjusted the register number ranges, make
sure REG matches. Otherwise some_was_live will be clear
when it shouldn't have been, and we'll create incorrect
REG_UNUSED notes. */
reg = gen_rtx_REG (outer_mode, regno_first);
}
else
{
/* If the number of words in the subreg is less than the number
of words in the full register, we have a well-defined partial
set. Otherwise the high bits are undefined.
This is only really applicable to pseudos, since we just took
care of multi-word hard registers. */
if (((GET_MODE_SIZE (outer_mode)
+ UNITS_PER_WORD - 1) / UNITS_PER_WORD)
< ((GET_MODE_SIZE (inner_mode)
+ UNITS_PER_WORD - 1) / UNITS_PER_WORD))
not_dead = (unsigned long) REGNO_REG_SET_P (pbi->reg_live,
regno_first);
reg = SUBREG_REG (reg);
}
}
else
reg = SUBREG_REG (reg);
break;
default:
break;
}
/* If this set is a MEM, then it kills any aliased writes.
If this set is a REG, then it kills any MEMs which use the reg. */
if (optimize && (flags & PROP_SCAN_DEAD_STORES))
{
if (REG_P (reg))
invalidate_mems_from_set (pbi, reg);
/* If the memory reference had embedded side effects (autoincrement
address modes) then we may need to kill some entries on the
memory set list. */
if (insn && MEM_P (reg))
for_each_rtx (&PATTERN (insn), invalidate_mems_from_autoinc, pbi);
if (MEM_P (reg) && ! side_effects_p (reg)
/* ??? With more effort we could track conditional memory life. */
&& ! cond)
add_to_mem_set_list (pbi, canon_rtx (reg));
}
if (REG_P (reg)
&& ! (regno_first == FRAME_POINTER_REGNUM
&& (! reload_completed || frame_pointer_needed))
#if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM
&& ! (regno_first == HARD_FRAME_POINTER_REGNUM
&& (! reload_completed || frame_pointer_needed))
#endif
#if FRAME_POINTER_REGNUM != ARG_POINTER_REGNUM
&& ! (regno_first == ARG_POINTER_REGNUM && fixed_regs[regno_first])
#endif
)
{
int some_was_live = 0, some_was_dead = 0;
for (i = regno_first; i <= regno_last; ++i)
{
int needed_regno = REGNO_REG_SET_P (pbi->reg_live, i);
if (pbi->local_set)
{
/* Order of the set operation matters here since both
sets may be the same. */
CLEAR_REGNO_REG_SET (pbi->cond_local_set, i);
if (cond != NULL_RTX
&& ! REGNO_REG_SET_P (pbi->local_set, i))
SET_REGNO_REG_SET (pbi->cond_local_set, i);
else
SET_REGNO_REG_SET (pbi->local_set, i);
}
if (code != CLOBBER)
SET_REGNO_REG_SET (pbi->new_set, i);
some_was_live |= needed_regno;
some_was_dead |= ! needed_regno;
}
#ifdef HAVE_conditional_execution
/* Consider conditional death in deciding that the register needs
a death note. */
if (some_was_live && ! not_dead
/* The stack pointer is never dead. Well, not strictly true,
but it's very difficult to tell from here. Hopefully
combine_stack_adjustments will fix up the most egregious
errors. */
&& regno_first != STACK_POINTER_REGNUM)
{
for (i = regno_first; i <= regno_last; ++i)
if (! mark_regno_cond_dead (pbi, i, cond))
not_dead |= ((unsigned long) 1) << (i - regno_first);
}
#endif
/* Additional data to record if this is the final pass. */
if (flags & (PROP_LOG_LINKS | PROP_REG_INFO
| PROP_DEATH_NOTES | PROP_AUTOINC))
{
rtx y;
int blocknum = pbi->bb->index;
y = NULL_RTX;
if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
{
y = pbi->reg_next_use[regno_first];
/* The next use is no longer next, since a store intervenes. */
for (i = regno_first; i <= regno_last; ++i)
pbi->reg_next_use[i] = 0;
}
if (flags & PROP_REG_INFO)
{
for (i = regno_first; i <= regno_last; ++i)
{
/* Count (weighted) references, stores, etc. This counts a
register twice if it is modified, but that is correct. */
REG_N_SETS (i) += 1;
REG_N_REFS (i) += 1;
REG_FREQ (i) += REG_FREQ_FROM_BB (pbi->bb);
/* The insns where a reg is live are normally counted
elsewhere, but we want the count to include the insn
where the reg is set, and the normal counting mechanism
would not count it. */
REG_LIVE_LENGTH (i) += 1;
}
/* If this is a hard reg, record this function uses the reg. */
if (regno_first < FIRST_PSEUDO_REGISTER)
{
for (i = regno_first; i <= regno_last; i++)
regs_ever_live[i] = 1;
if (flags & PROP_ASM_SCAN)
for (i = regno_first; i <= regno_last; i++)
regs_asm_clobbered[i] = 1;
}
else
{
/* Keep track of which basic blocks each reg appears in. */
if (REG_BASIC_BLOCK (regno_first) == REG_BLOCK_UNKNOWN)
REG_BASIC_BLOCK (regno_first) = blocknum;
else if (REG_BASIC_BLOCK (regno_first) != blocknum)
REG_BASIC_BLOCK (regno_first) = REG_BLOCK_GLOBAL;
}
}
if (! some_was_dead)
{
if (flags & PROP_LOG_LINKS)
{
/* Make a logical link from the next following insn
that uses this register, back to this insn.
The following insns have already been processed.
We don't build a LOG_LINK for hard registers containing
in ASM_OPERANDs. If these registers get replaced,
we might wind up changing the semantics of the insn,
even if reload can make what appear to be valid
assignments later.
We don't build a LOG_LINK for global registers to
or from a function call. We don't want to let
combine think that it knows what is going on with
global registers. */
if (y && (BLOCK_NUM (y) == blocknum)
&& (regno_first >= FIRST_PSEUDO_REGISTER
|| (asm_noperands (PATTERN (y)) < 0
&& ! ((CALL_P (insn)
|| CALL_P (y))
&& global_regs[regno_first]))))
LOG_LINKS (y) = alloc_INSN_LIST (insn, LOG_LINKS (y));
}
}
else if (not_dead)
;
else if (! some_was_live)
{
if (flags & PROP_REG_INFO)
REG_N_DEATHS (regno_first) += 1;
if (flags & PROP_DEATH_NOTES)
{
/* Note that dead stores have already been deleted
when possible. If we get here, we have found a
dead store that cannot be eliminated (because the
same insn does something useful). Indicate this
by marking the reg being set as dying here. */
REG_NOTES (insn)
= alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
}
}
else
{
if (flags & PROP_DEATH_NOTES)
{
/* This is a case where we have a multi-word hard register
and some, but not all, of the words of the register are
needed in subsequent insns. Write REG_UNUSED notes
for those parts that were not needed. This case should
be rare. */
for (i = regno_first; i <= regno_last; ++i)
if (! REGNO_REG_SET_P (pbi->reg_live, i))
REG_NOTES (insn)
= alloc_EXPR_LIST (REG_UNUSED,
regno_reg_rtx[i],
REG_NOTES (insn));
}
}
}
/* Mark the register as being dead. */
if (some_was_live
/* The stack pointer is never dead. Well, not strictly true,
but it's very difficult to tell from here. Hopefully
combine_stack_adjustments will fix up the most egregious
errors. */
&& regno_first != STACK_POINTER_REGNUM)
{
for (i = regno_first; i <= regno_last; ++i)
if (!(not_dead & (((unsigned long) 1) << (i - regno_first))))
{
if ((pbi->flags & PROP_REG_INFO)
&& REGNO_REG_SET_P (pbi->reg_live, i))
{
REG_LIVE_LENGTH (i) += pbi->insn_num - reg_deaths[i];
reg_deaths[i] = 0;
}
CLEAR_REGNO_REG_SET (pbi->reg_live, i);
}
}
}
else if (REG_P (reg))
{
if (flags & (PROP_LOG_LINKS | PROP_AUTOINC))
pbi->reg_next_use[regno_first] = 0;
if ((flags & PROP_REG_INFO) != 0
&& (flags & PROP_ASM_SCAN) != 0
&& regno_first < FIRST_PSEUDO_REGISTER)
{
for (i = regno_first; i <= regno_last; i++)
regs_asm_clobbered[i] = 1;
}
}
/* If this is the last pass and this is a SCRATCH, show it will be dying
here and count it. */
else if (GET_CODE (reg) == SCRATCH)
{
if (flags & PROP_DEATH_NOTES)
REG_NOTES (insn)
= alloc_EXPR_LIST (REG_UNUSED, reg, REG_NOTES (insn));
}
}
#ifdef HAVE_conditional_execution
/* Mark REGNO conditionally dead.
Return true if the register is now unconditionally dead. */
static int
mark_regno_cond_dead (struct propagate_block_info *pbi, int regno, rtx cond)
{
/* If this is a store to a predicate register, the value of the
predicate is changing, we don't know that the predicate as seen
before is the same as that seen after. Flush all dependent
conditions from reg_cond_dead. This will make all such
conditionally live registers unconditionally live. */
if (REGNO_REG_SET_P (pbi->reg_cond_reg, regno))
flush_reg_cond_reg (pbi, regno);
/* If this is an unconditional store, remove any conditional
life that may have existed. */
if (cond == NULL_RTX)
splay_tree_remove (pbi->reg_cond_dead, regno);
else
{
splay_tree_node node;
struct reg_cond_life_info *rcli;
rtx ncond;
/* Otherwise this is a conditional set. Record that fact.
It may have been conditionally used, or there may be a
subsequent set with a complementary condition. */
node = splay_tree_lookup (pbi->reg_cond_dead, regno);
if (node == NULL)
{
/* The register was unconditionally live previously.
Record the current condition as the condition under
which it is dead. */
rcli = xmalloc (sizeof (*rcli));
rcli->condition = cond;
rcli->stores = cond;
rcli->orig_condition = const0_rtx;
splay_tree_insert (pbi->reg_cond_dead, regno,
(splay_tree_value) rcli);
SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
/* Not unconditionally dead. */
return 0;
}
else
{
/* The register was conditionally live previously.
Add the new condition to the old. */
rcli = (struct reg_cond_life_info *) node->value;
ncond = rcli->condition;
ncond = ior_reg_cond (ncond, cond, 1);
if (rcli->stores == const0_rtx)
rcli->stores = cond;
else if (rcli->stores != const1_rtx)
rcli->stores = ior_reg_cond (rcli->stores, cond, 1);
/* If the register is now unconditionally dead, remove the entry
in the splay_tree. A register is unconditionally dead if the
dead condition ncond is true. A register is also unconditionally
dead if the sum of all conditional stores is an unconditional
store (stores is true), and the dead condition is identically the
same as the original dead condition initialized at the end of
the block. This is a pointer compare, not an rtx_equal_p
compare. */
if (ncond == const1_rtx
|| (ncond == rcli->orig_condition && rcli->stores == const1_rtx))
splay_tree_remove (pbi->reg_cond_dead, regno);
else
{
rcli->condition = ncond;
SET_REGNO_REG_SET (pbi->reg_cond_reg, REGNO (XEXP (cond, 0)));
/* Not unconditionally dead. */
return 0;
}
}
}
return 1;
}
/* Called from splay_tree_delete for pbi->reg_cond_life. */
static void
free_reg_cond_life_info (splay_tree_value value)
{
struct reg_cond_life_info *rcli = (struct reg_cond_life_info *) value;
free (rcli);
}
/* Helper function for flush_reg_cond_reg. */
static int
flush_reg_cond_reg_1 (splay_tree_node node, void *data)
{
struct reg_cond_life_info *rcli;
int *xdata = (int *) data;
unsigned int regno = xdata[0];
/* Don't need to search if last flushed value was farther on in
the in-order traversal. */
if (xdata[1] >= (int) node->key)
return 0;
/* Splice out portions of the expression that refer to regno. */
rcli = (struct reg_cond_life_info *) node->value;
rcli->condition = elim_reg_cond (rcli->condition, regno);
if (rcli->stores != const0_rtx && rcli->stores != const1_rtx)
rcli->stores = elim_reg_cond (rcli->stores, regno);
/* If the entire condition is now false, signal the node to be removed. */
if (rcli->condition == const0_rtx)
{
xdata[1] = node->key;
return -1;
}
else
gcc_assert (rcli->condition != const1_rtx);
return 0;
}
/* Flush all (sub) expressions referring to REGNO from REG_COND_LIVE. */
static void
flush_reg_cond_reg (struct propagate_block_info *pbi, int regno)
{
int pair[2];
pair[0] = regno;
pair[1] = -1;
while (splay_tree_foreach (pbi->reg_cond_dead,
flush_reg_cond_reg_1, pair) == -1)
splay_tree_remove (pbi->reg_cond_dead, pair[1]);
CLEAR_REGNO_REG_SET (pbi->reg_cond_reg, regno);
}
/* Logical arithmetic on predicate conditions. IOR, NOT and AND.
For ior/and, the ADD flag determines whether we want to add the new
condition X to the old one unconditionally. If it is zero, we will
only return a new expression if X allows us to simplify part of
OLD, otherwise we return NULL to the caller.
If ADD is nonzero, we will return a new condition in all cases. The
toplevel caller of one of these functions should always pass 1 for
ADD. */
static rtx
ior_reg_cond (rtx old, rtx x, int add)
{
rtx op0, op1;
if (COMPARISON_P (old))
{
if (COMPARISON_P (x)
&& REVERSE_CONDEXEC_PREDICATES_P (x, old)
&& REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
return const1_rtx;
if (GET_CODE (x) == GET_CODE (old)
&& REGNO (XEXP (x, 0)) == REGNO (XEXP (old, 0)))
return old;
if (! add)
return NULL;
return gen_rtx_IOR (0, old, x);
}
switch (GET_CODE (old))
{
case IOR:
op0 = ior_reg_cond (XEXP (old, 0), x, 0);
op1 = ior_reg_cond (XEXP (old, 1), x, 0);
if (op0 != NULL || op1 != NULL)
{
if (op0 == const0_rtx)
return op1 ? op1 : gen_rtx_IOR (0, XEXP (old, 1), x);
if (op1 == const0_rtx)
return op0 ? op0 : gen_rtx_IOR (0, XEXP (old, 0), x);
if (op0 == const1_rtx || op1 == const1_rtx)
return const1_rtx;
if (op0 == NULL)
op0 = gen_rtx_IOR (0, XEXP (old, 0), x);
else if (rtx_equal_p (x, op0))
/* (x | A) | x ~ (x | A). */
return old;
if (op1 == NULL)
op1 = gen_rtx_IOR (0, XEXP (old, 1), x);
else if (rtx_equal_p (x, op1))
/* (A | x) | x ~ (A | x). */
return old;
return gen_rtx_IOR (0, op0, op1);
}
if (! add)
return NULL;
return gen_rtx_IOR (0, old, x);
case AND:
op0 = ior_reg_cond (XEXP (old, 0), x, 0);
op1 = ior_reg_cond (XEXP (old, 1), x, 0);
if (op0 != NULL || op1 != NULL)
{
if (op0 == const1_rtx)
return op1 ? op1 : gen_rtx_IOR (0, XEXP (old, 1), x);
if (op1 == const1_rtx)
return op0 ? op0 : gen_rtx_IOR (0, XEXP (old, 0), x);
if (op0 == const0_rtx || op1 == const0_rtx)
return const0_rtx;
if (op0 == NULL)
op0 = gen_rtx_IOR (0, XEXP (old, 0), x);
else if (rtx_equal_p (x, op0))
/* (x & A) | x ~ x. */
return op0;
if (op1 == NULL)
op1 = gen_rtx_IOR (0, XEXP (old, 1), x);
else if (rtx_equal_p (x, op1))
/* (A & x) | x ~ x. */
return op1;
return gen_rtx_AND (0, op0, op1);
}
if (! add)
return NULL;
return gen_rtx_IOR (0, old, x);
case NOT:
op0 = and_reg_cond (XEXP (old, 0), not_reg_cond (x), 0);
if (op0 != NULL)
return not_reg_cond (op0);
if (! add)
return NULL;
return gen_rtx_IOR (0, old, x);
default:
gcc_unreachable ();
}
}
static rtx
not_reg_cond (rtx x)
{
if (x == const0_rtx)
return const1_rtx;
else if (x == const1_rtx)
return const0_rtx;
if (GET_CODE (x) == NOT)
return XEXP (x, 0);
if (COMPARISON_P (x)
&& REG_P (XEXP (x, 0)))
{
gcc_assert (XEXP (x, 1) == const0_rtx);
return gen_rtx_fmt_ee (reversed_comparison_code (x, NULL),
VOIDmode, XEXP (x, 0), const0_rtx);
}
return gen_rtx_NOT (0, x);
}
static rtx
and_reg_cond (rtx old, rtx x, int add)
{
rtx op0, op1;
if (COMPARISON_P (old))
{
if (COMPARISON_P (x)
&& GET_CODE (x) == reversed_comparison_code (old, NULL)
&& REGNO (XEXP (x,