/* Move registers around to reduce number of move instructions needed.
Copyright (C) 1987, 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
- 1999, 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
+ 1999, 2000, 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
This file is part of GCC.
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. */
+Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301, USA. */
/* This module looks for cases where matching constraints would force
#include "except.h"
#include "toplev.h"
#include "reload.h"
+#include "timevar.h"
+#include "tree-pass.h"
-/* Turn STACK_GROWS_DOWNWARD into a boolean. */
-#ifdef STACK_GROWS_DOWNWARD
-#undef STACK_GROWS_DOWNWARD
-#define STACK_GROWS_DOWNWARD 1
-#else
-#define STACK_GROWS_DOWNWARD 0
-#endif
-
static int perhaps_ends_bb_p (rtx);
static int optimize_reg_copy_1 (rtx, rtx, rtx);
static void optimize_reg_copy_2 (rtx, rtx, rtx);
static void optimize_reg_copy_3 (rtx, rtx, rtx);
-static void copy_src_to_dest (rtx, rtx, rtx, int);
-static int *regmove_bb_head;
+static void copy_src_to_dest (rtx, rtx, rtx);
struct match {
int with[MAX_RECOG_OPERANDS];
static int try_auto_increment (rtx, rtx, rtx, rtx, HOST_WIDE_INT, int);
static int find_matches (rtx, struct match *);
static void replace_in_call_usage (rtx *, unsigned int, rtx, rtx);
-static int fixup_match_1 (rtx, rtx, rtx, rtx, rtx, int, int, int, FILE *);
-static int reg_is_remote_constant_p (rtx, rtx, rtx);
+static int fixup_match_1 (rtx, rtx, rtx, rtx, rtx, int, int, int);
static int stable_and_no_regs_but_for_p (rtx, rtx, rtx);
static int regclass_compatible_p (int, int);
static int replacement_quality (rtx);
-static int fixup_match_2 (rtx, rtx, rtx, rtx, FILE *);
+static int fixup_match_2 (rtx, rtx, rtx, rtx);
/* Return nonzero if registers with CLASS1 and CLASS2 can be merged without
causing too much register allocation problems. */
/* If there is a REG_DEAD note on this insn, we must
change this not to REG_UNUSED meaning that the register
is set, but the value is dead. Failure to do so will
- result in a sched1 abort -- when it recomputes lifetime
+ result in a sched1 dieing -- when it recomputes lifetime
information, the number of REG_DEAD notes will have
changed. */
rtx note = find_reg_note (insn, REG_DEAD, reg);
{
int i;
for (i = 0; i < flags_nregs; ++i)
- live |= REGNO_REG_SET_P (block->global_live_at_start,
+ live |= REGNO_REG_SET_P (block->il.rtl->global_live_at_start,
flags_regno + i);
}
#endif
if (sregno < FIRST_PSEUDO_REGISTER
&& reg_mentioned_p (dest, PATTERN (q)))
failed = 1;
+
+ /* Attempt to replace all uses. */
+ else if (!validate_replace_rtx (src, dest, q))
+ failed = 1;
- /* Replace all uses and make sure that the register
- isn't still present. */
- else if (validate_replace_rtx (src, dest, q)
- && (sregno >= FIRST_PSEUDO_REGISTER
- || ! reg_overlap_mentioned_p (src,
- PATTERN (q))))
- ;
- else
+ /* If this succeeded, but some part of the register
+ is still present, undo the replacement. */
+ else if (sregno < FIRST_PSEUDO_REGISTER
+ && reg_overlap_mentioned_p (src, PATTERN (q)))
{
validate_replace_rtx (dest, src, q);
failed = 1;
if (reg_mentioned_p (dest, PATTERN (q)))
PATTERN (q) = replace_rtx (PATTERN (q), dest, src);
-
- if (CALL_P (q))
- {
- REG_N_CALLS_CROSSED (dregno)--;
- REG_N_CALLS_CROSSED (sregno)++;
- }
+ if (CALL_P (q))
+ {
+ REG_N_CALLS_CROSSED (dregno)--;
+ REG_N_CALLS_CROSSED (sregno)++;
+ }
}
remove_note (p, find_reg_note (p, REG_DEAD, dest));
break;
}
}
+
/* INSN is a ZERO_EXTEND or SIGN_EXTEND of SRC to DEST.
Look if SRC dies there, and if it is only set once, by loading
it from memory. If so, try to incorporate the zero/sign extension
rtx src_reg = XEXP (src, 0);
int src_no = REGNO (src_reg);
int dst_no = REGNO (dest);
- rtx p, set, subreg;
+ rtx p, set;
enum machine_mode old_mode;
if (src_no < FIRST_PSEUDO_REGISTER
/* Now walk forward making additional replacements. We want to be able
to undo all the changes if a later substitution fails. */
- subreg = gen_lowpart_SUBREG (old_mode, src_reg);
while (p = NEXT_INSN (p), p != insn)
{
if (! INSN_P (p))
continue;
/* Make a tentative change. */
- validate_replace_rtx_group (src_reg, subreg, p);
+ validate_replace_rtx_group (src_reg,
+ gen_lowpart_SUBREG (old_mode, src_reg),
+ p);
}
validate_replace_rtx_group (src, src_reg, insn);
instead moving the value to dest directly before the operation. */
static void
-copy_src_to_dest (rtx insn, rtx src, rtx dest, int old_max_uid)
+copy_src_to_dest (rtx insn, rtx src, rtx dest)
{
rtx seq;
rtx link;
if (REG_P (src)
&& REG_LIVE_LENGTH (REGNO (src)) > 0
&& REG_P (dest)
- && !RTX_UNCHANGING_P (dest)
&& REG_LIVE_LENGTH (REGNO (dest)) > 0
&& (set = single_set (insn)) != NULL_RTX
&& !reg_mentioned_p (dest, SET_SRC (set))
*p_move_notes = NULL_RTX;
*p_insn_notes = NULL_RTX;
- /* Is the insn the head of a basic block? If so extend it. */
insn_uid = INSN_UID (insn);
move_uid = INSN_UID (move_insn);
- if (insn_uid < old_max_uid)
- {
- bb = regmove_bb_head[insn_uid];
- if (bb >= 0)
- {
- BB_HEAD (BASIC_BLOCK (bb)) = move_insn;
- regmove_bb_head[insn_uid] = -1;
- }
- }
/* Update the various register tables. */
dest_regno = REGNO (dest);
if (REGNO_LAST_UID (src_regno) == insn_uid)
REGNO_LAST_UID (src_regno) = move_uid;
-
- if (REGNO_LAST_NOTE_UID (src_regno) == insn_uid)
- REGNO_LAST_NOTE_UID (src_regno) = move_uid;
}
}
+/* reg_set_in_bb[REGNO] points to basic block iff the register is set
+ only once in the given block and has REG_EQUAL note. */
+
+basic_block *reg_set_in_bb;
+
+/* Size of reg_set_in_bb array. */
+static unsigned int max_reg_computed;
+
\f
/* Return whether REG is set in only one location, and is set to a
constant, but is set in a different basic block from INSN (an
may increase register pressure and make reload harder. If REG is
set in the same basic block as INSN, we don't worry about it,
because we'll probably need a register anyhow (??? but what if REG
- is used in a different basic block as well as this one?). FIRST is
- the first insn in the function. */
+ is used in a different basic block as well as this one?). */
-static int
-reg_is_remote_constant_p (rtx reg, rtx insn, rtx first)
+static bool
+reg_is_remote_constant_p (rtx reg, rtx insn)
{
+ basic_block bb;
rtx p;
+ int max;
- if (REG_N_SETS (REGNO (reg)) != 1)
- return 0;
-
- /* Look for the set. */
- for (p = LOG_LINKS (insn); p; p = XEXP (p, 1))
+ if (!reg_set_in_bb)
{
- rtx s;
-
- if (REG_NOTE_KIND (p) != 0)
- continue;
- s = single_set (XEXP (p, 0));
- if (s != 0
- && REG_P (SET_DEST (s))
- && REGNO (SET_DEST (s)) == REGNO (reg))
- {
- /* The register is set in the same basic block. */
- return 0;
- }
- }
+ max_reg_computed = max = max_reg_num ();
+ reg_set_in_bb = xcalloc (max, sizeof (*reg_set_in_bb));
- for (p = first; p && p != insn; p = NEXT_INSN (p))
- {
- rtx s;
+ FOR_EACH_BB (bb)
+ FOR_BB_INSNS (bb, p)
+ {
+ rtx s;
- if (! INSN_P (p))
- continue;
- s = single_set (p);
- if (s != 0
- && REG_P (SET_DEST (s))
- && REGNO (SET_DEST (s)) == REGNO (reg))
- {
- /* This is the instruction which sets REG. If there is a
- REG_EQUAL note, then REG is equivalent to a constant. */
- if (find_reg_note (p, REG_EQUAL, NULL_RTX))
- return 1;
- return 0;
- }
+ if (!INSN_P (p))
+ continue;
+ s = single_set (p);
+ /* This is the instruction which sets REG. If there is a
+ REG_EQUAL note, then REG is equivalent to a constant. */
+ if (s != 0
+ && REG_P (SET_DEST (s))
+ && REG_N_SETS (REGNO (SET_DEST (s))) == 1
+ && find_reg_note (p, REG_EQUAL, NULL_RTX))
+ reg_set_in_bb[REGNO (SET_DEST (s))] = bb;
+ }
}
- return 0;
+ gcc_assert (REGNO (reg) < max_reg_computed);
+ if (reg_set_in_bb[REGNO (reg)] == NULL)
+ return false;
+ return (reg_set_in_bb[REGNO (reg)] != BLOCK_FOR_INSN (insn));
}
/* INSN is adding a CONST_INT to a REG. We search backwards looking for
hard register as ultimate source, like the frame pointer. */
static int
-fixup_match_2 (rtx insn, rtx dst, rtx src, rtx offset, FILE *regmove_dump_file)
+fixup_match_2 (rtx insn, rtx dst, rtx src, rtx offset)
{
rtx p, dst_death = 0;
int length, num_calls = 0;
REG_N_CALLS_CROSSED (REGNO (dst)) += num_calls;
}
- if (regmove_dump_file)
- fprintf (regmove_dump_file,
+ if (dump_file)
+ fprintf (dump_file,
"Fixed operand of insn %d.\n",
INSN_UID (insn));
REGMOVE_DUMP_FILE is a stream for output of a trace of actions taken
(or 0 if none should be output). */
-void
-regmove_optimize (rtx f, int nregs, FILE *regmove_dump_file)
+static void
+regmove_optimize (rtx f, int nregs)
{
- int old_max_uid = get_max_uid ();
rtx insn;
struct match match;
int pass;
can suppress some optimizations in those zones. */
mark_flags_life_zones (discover_flags_reg ());
- regno_src_regno = xmalloc (sizeof *regno_src_regno * nregs);
- for (i = nregs; --i >= 0; ) regno_src_regno[i] = -1;
-
- regmove_bb_head = xmalloc (sizeof (int) * (old_max_uid + 1));
- for (i = old_max_uid; i >= 0; i--) regmove_bb_head[i] = -1;
- FOR_EACH_BB (bb)
- regmove_bb_head[INSN_UID (BB_HEAD (bb))] = bb->index;
+ regno_src_regno = XNEWVEC (int, nregs);
+ for (i = nregs; --i >= 0; )
+ regno_src_regno[i] = -1;
/* A forward/backward pass. Replace output operands with input operands. */
if (! flag_regmove && pass >= flag_expensive_optimizations)
goto done;
- if (regmove_dump_file)
- fprintf (regmove_dump_file, "Starting %s pass...\n",
+ if (dump_file)
+ fprintf (dump_file, "Starting %s pass...\n",
pass ? "backward" : "forward");
for (insn = pass ? get_last_insn () : f; insn;
&& GET_MODE_SIZE (GET_MODE (dst))
>= GET_MODE_SIZE (GET_MODE (SUBREG_REG (dst))))
{
- src_subreg
- = gen_rtx_SUBREG (GET_MODE (SUBREG_REG (dst)),
- src, SUBREG_BYTE (dst));
dst = SUBREG_REG (dst);
+ src_subreg = lowpart_subreg (GET_MODE (dst),
+ src, GET_MODE (src));
+ if (!src_subreg)
+ continue;
}
if (!REG_P (dst)
|| REGNO (dst) < FIRST_PSEUDO_REGISTER)
continue;
if (fixup_match_1 (insn, set, src, src_subreg, dst, pass,
- op_no, match_no,
- regmove_dump_file))
+ op_no, match_no))
break;
}
}
/* A backward pass. Replace input operands with output operands. */
- if (regmove_dump_file)
- fprintf (regmove_dump_file, "Starting backward pass...\n");
+ if (dump_file)
+ fprintf (dump_file, "Starting backward pass...\n");
for (insn = get_last_insn (); insn; insn = PREV_INSN (insn))
{
if (!REG_P (dst)
|| REGNO (dst) < FIRST_PSEUDO_REGISTER
|| REG_LIVE_LENGTH (REGNO (dst)) < 0
- || RTX_UNCHANGING_P (dst)
|| GET_MODE (src) != GET_MODE (dst))
continue;
&& GET_CODE (XEXP (SET_SRC (set), 1)) == CONST_INT
&& XEXP (SET_SRC (set), 0) == src
&& fixup_match_2 (insn, dst, src,
- XEXP (SET_SRC (set), 1),
- regmove_dump_file))
+ XEXP (SET_SRC (set), 1)))
break;
continue;
}
it for this optimization, as this would make it
no longer equivalent to a constant. */
- if (reg_is_remote_constant_p (src, insn, f))
+ if (reg_is_remote_constant_p (src, insn))
{
if (!copy_src)
{
}
- if (regmove_dump_file)
- fprintf (regmove_dump_file,
+ if (dump_file)
+ fprintf (dump_file,
"Could fix operand %d of insn %d matching operand %d.\n",
op_no, INSN_UID (insn), match_no);
break;
}
+ /* We can't make this change if SRC is read or
+ partially written in P, since we are going to
+ eliminate SRC. We can't make this change
+ if DST is mentioned at all in P,
+ since we are going to change its value. */
if (reg_overlap_mentioned_p (src, PATTERN (p))
- || reg_overlap_mentioned_p (dst, PATTERN (p)))
+ || reg_mentioned_p (dst, PATTERN (p)))
break;
/* If we have passed a call instruction, and the
REG_LIVE_LENGTH (srcno) = 2;
}
- if (regmove_dump_file)
- fprintf (regmove_dump_file,
+ if (dump_file)
+ fprintf (dump_file,
"Fixed operand %d of insn %d matching operand %d.\n",
op_no, INSN_UID (insn), match_no);
/* If we weren't able to replace any of the alternatives, try an
alternative approach of copying the source to the destination. */
if (!success && copy_src != NULL_RTX)
- copy_src_to_dest (insn, copy_src, copy_dst, old_max_uid);
+ copy_src_to_dest (insn, copy_src, copy_dst);
}
}
- /* In fixup_match_1, some insns may have been inserted after basic block
- ends. Fix that here. */
- FOR_EACH_BB (bb)
- {
- rtx end = BB_END (bb);
- rtx new = end;
- rtx next = NEXT_INSN (new);
- while (next != 0 && INSN_UID (next) >= old_max_uid
- && (bb->next_bb == EXIT_BLOCK_PTR || BB_HEAD (bb->next_bb) != next))
- new = next, next = NEXT_INSN (new);
- BB_END (bb) = new;
- }
-
done:
/* Clean up. */
free (regno_src_regno);
- free (regmove_bb_head);
+ if (reg_set_in_bb)
+ {
+ free (reg_set_in_bb);
+ reg_set_in_bb = NULL;
+ }
}
/* Returns nonzero if INSN's pattern has matching constraints for any operand.
static int
fixup_match_1 (rtx insn, rtx set, rtx src, rtx src_subreg, rtx dst,
- int backward, int operand_number, int match_number,
- FILE *regmove_dump_file)
+ int backward, int operand_number, int match_number)
{
rtx p;
rtx post_inc = 0, post_inc_set = 0, search_end = 0;
rtx src_note = find_reg_note (insn, REG_DEAD, src), dst_note = NULL_RTX;
int length, s_length;
- /* If SRC is marked as unchanging, we may not change it.
- ??? Maybe we could get better code by removing the unchanging bit
- instead, and changing it back if we don't succeed? */
- if (RTX_UNCHANGING_P (src))
- return 0;
-
if (! src_note)
{
/* Look for (set (regX) (op regA constX))
code = NOTE;
}
- if (regmove_dump_file)
- fprintf (regmove_dump_file,
+ if (dump_file)
+ fprintf (dump_file,
"Could fix operand %d of insn %d matching operand %d.\n",
operand_number, INSN_UID (insn), match_number);
then do not use it for this optimization. We want the equivalence
so that if we have to reload this register, we can reload the
constant, rather than extending the lifespan of the register. */
- if (reg_is_remote_constant_p (src, insn, get_insns ()))
+ if (reg_is_remote_constant_p (src, insn))
return 0;
/* Scan forward to find the next instruction that
{
rtx notes = REG_NOTES (insn);
- emit_insn_after_with_line_notes (pat, PREV_INSN (p), insn);
+ p = emit_insn_after_setloc (pat, PREV_INSN (p), INSN_LOCATOR (insn));
delete_insn (insn);
- /* emit_insn_after_with_line_notes has no
- return value, so search for the new insn. */
- insn = p;
- while (! INSN_P (insn) || PATTERN (insn) != pat)
- insn = PREV_INSN (insn);
-
- REG_NOTES (insn) = notes;
+ REG_NOTES (p) = notes;
}
}
/* Sometimes we'd generate src = const; src += n;
if (REG_LIVE_LENGTH (REGNO (dst)) < 2)
REG_LIVE_LENGTH (REGNO (dst)) = 2;
}
- if (regmove_dump_file)
- fprintf (regmove_dump_file,
+ if (dump_file)
+ fprintf (dump_file,
"Fixed operand %d of insn %d matching operand %d.\n",
operand_number, INSN_UID (insn), match_number);
return 1;
mentioning SRC or mentioning / changing DST . If in doubt, presume
it is unstable.
The rationale is that we want to check if we can move an insn easily
- while just paying attention to SRC and DST. A register is considered
- stable if it has the RTX_UNCHANGING_P bit set, but that would still
- leave the burden to update REG_DEAD / REG_UNUSED notes, so we don't
- want any registers but SRC and DST. */
+ while just paying attention to SRC and DST. */
static int
stable_and_no_regs_but_for_p (rtx x, rtx src, rtx dst)
{
}
}
\f
-/* Track stack adjustments and stack memory references. Attempt to
- reduce the number of stack adjustments by back-propagating across
- the memory references.
-
- This is intended primarily for use with targets that do not define
- ACCUMULATE_OUTGOING_ARGS. It is of significantly more value to
- targets that define PREFERRED_STACK_BOUNDARY more aligned than
- STACK_BOUNDARY (e.g. x86), or if not all registers can be pushed
- (e.g. x86 fp regs) which would ordinarily have to be implemented
- as a sub/mov pair due to restrictions in calls.c.
-
- Propagation stops when any of the insns that need adjusting are
- (a) no longer valid because we've exceeded their range, (b) a
- non-trivial push instruction, or (c) a call instruction.
-
- Restriction B is based on the assumption that push instructions
- are smaller or faster. If a port really wants to remove all
- pushes, it should have defined ACCUMULATE_OUTGOING_ARGS. The
- one exception that is made is for an add immediately followed
- by a push. */
-
-/* This structure records stack memory references between stack adjusting
- instructions. */
-
-struct csa_memlist
-{
- HOST_WIDE_INT sp_offset;
- rtx insn, *mem;
- struct csa_memlist *next;
-};
-
-static int stack_memref_p (rtx);
-static rtx single_set_for_csa (rtx);
-static void free_csa_memlist (struct csa_memlist *);
-static struct csa_memlist *record_one_stack_memref (rtx, rtx *,
- struct csa_memlist *);
-static int try_apply_stack_adjustment (rtx, struct csa_memlist *,
- HOST_WIDE_INT, HOST_WIDE_INT);
-static void combine_stack_adjustments_for_block (basic_block);
-static int record_stack_memrefs (rtx *, void *);
-
-
-/* Main entry point for stack adjustment combination. */
-void
-combine_stack_adjustments (void)
+static bool
+gate_handle_regmove (void)
{
- basic_block bb;
-
- FOR_EACH_BB (bb)
- combine_stack_adjustments_for_block (bb);
+ return (optimize > 0 && flag_regmove);
}
-/* Recognize a MEM of the form (sp) or (plus sp const). */
-
-static int
-stack_memref_p (rtx x)
+/* Register allocation pre-pass, to reduce number of moves necessary
+ for two-address machines. */
+static unsigned int
+rest_of_handle_regmove (void)
{
- if (!MEM_P (x))
- return 0;
- x = XEXP (x, 0);
-
- if (x == stack_pointer_rtx)
- return 1;
- if (GET_CODE (x) == PLUS
- && XEXP (x, 0) == stack_pointer_rtx
- && GET_CODE (XEXP (x, 1)) == CONST_INT)
- return 1;
-
+ regmove_optimize (get_insns (), max_reg_num ());
+ cleanup_cfg (CLEANUP_EXPENSIVE | CLEANUP_UPDATE_LIFE);
return 0;
}
-/* Recognize either normal single_set or the hack in i386.md for
- tying fp and sp adjustments. */
-
-static rtx
-single_set_for_csa (rtx insn)
-{
- int i;
- rtx tmp = single_set (insn);
- if (tmp)
- return tmp;
-
- if (!NONJUMP_INSN_P (insn)
- || GET_CODE (PATTERN (insn)) != PARALLEL)
- return NULL_RTX;
-
- tmp = PATTERN (insn);
- if (GET_CODE (XVECEXP (tmp, 0, 0)) != SET)
- return NULL_RTX;
-
- for (i = 1; i < XVECLEN (tmp, 0); ++i)
- {
- rtx this = XVECEXP (tmp, 0, i);
-
- /* The special case is allowing a no-op set. */
- if (GET_CODE (this) == SET
- && SET_SRC (this) == SET_DEST (this))
- ;
- else if (GET_CODE (this) != CLOBBER
- && GET_CODE (this) != USE)
- return NULL_RTX;
- }
-
- return XVECEXP (tmp, 0, 0);
-}
-
-/* Free the list of csa_memlist nodes. */
-
-static void
-free_csa_memlist (struct csa_memlist *memlist)
-{
- struct csa_memlist *next;
- for (; memlist ; memlist = next)
- {
- next = memlist->next;
- free (memlist);
- }
-}
-
-/* Create a new csa_memlist node from the given memory reference.
- It is already known that the memory is stack_memref_p. */
-
-static struct csa_memlist *
-record_one_stack_memref (rtx insn, rtx *mem, struct csa_memlist *next_memlist)
-{
- struct csa_memlist *ml;
-
- ml = xmalloc (sizeof (*ml));
-
- if (XEXP (*mem, 0) == stack_pointer_rtx)
- ml->sp_offset = 0;
- else
- ml->sp_offset = INTVAL (XEXP (XEXP (*mem, 0), 1));
-
- ml->insn = insn;
- ml->mem = mem;
- ml->next = next_memlist;
-
- return ml;
-}
-
-/* Attempt to apply ADJUST to the stack adjusting insn INSN, as well
- as each of the memories in MEMLIST. Return true on success. */
-
-static int
-try_apply_stack_adjustment (rtx insn, struct csa_memlist *memlist, HOST_WIDE_INT new_adjust,
- HOST_WIDE_INT delta)
-{
- struct csa_memlist *ml;
- rtx set;
-
- set = single_set_for_csa (insn);
- validate_change (insn, &XEXP (SET_SRC (set), 1), GEN_INT (new_adjust), 1);
-
- for (ml = memlist; ml ; ml = ml->next)
- validate_change
- (ml->insn, ml->mem,
- replace_equiv_address_nv (*ml->mem,
- plus_constant (stack_pointer_rtx,
- ml->sp_offset - delta)), 1);
-
- if (apply_change_group ())
- {
- /* Succeeded. Update our knowledge of the memory references. */
- for (ml = memlist; ml ; ml = ml->next)
- ml->sp_offset -= delta;
-
- return 1;
- }
- else
- return 0;
-}
-
-/* Called via for_each_rtx and used to record all stack memory references in
- the insn and discard all other stack pointer references. */
-struct record_stack_memrefs_data
+struct tree_opt_pass pass_regmove =
{
- rtx insn;
- struct csa_memlist *memlist;
+ "regmove", /* name */
+ gate_handle_regmove, /* gate */
+ rest_of_handle_regmove, /* execute */
+ NULL, /* sub */
+ NULL, /* next */
+ 0, /* static_pass_number */
+ TV_REGMOVE, /* tv_id */
+ 0, /* properties_required */
+ 0, /* properties_provided */
+ 0, /* properties_destroyed */
+ 0, /* todo_flags_start */
+ TODO_dump_func |
+ TODO_ggc_collect, /* todo_flags_finish */
+ 'N' /* letter */
};
-static int
-record_stack_memrefs (rtx *xp, void *data)
-{
- rtx x = *xp;
- struct record_stack_memrefs_data *d =
- (struct record_stack_memrefs_data *) data;
- if (!x)
- return 0;
- switch (GET_CODE (x))
- {
- case MEM:
- if (!reg_mentioned_p (stack_pointer_rtx, x))
- return -1;
- /* We are not able to handle correctly all possible memrefs containing
- stack pointer, so this check is necessary. */
- if (stack_memref_p (x))
- {
- d->memlist = record_one_stack_memref (d->insn, xp, d->memlist);
- return -1;
- }
- return 1;
- case REG:
- /* ??? We want be able to handle non-memory stack pointer
- references later. For now just discard all insns referring to
- stack pointer outside mem expressions. We would probably
- want to teach validate_replace to simplify expressions first.
-
- We can't just compare with STACK_POINTER_RTX because the
- reference to the stack pointer might be in some other mode.
- In particular, an explicit clobber in an asm statement will
- result in a QImode clobber. */
- if (REGNO (x) == STACK_POINTER_REGNUM)
- return 1;
- break;
- default:
- break;
- }
- return 0;
-}
-
-/* Subroutine of combine_stack_adjustments, called for each basic block. */
-
-static void
-combine_stack_adjustments_for_block (basic_block bb)
-{
- HOST_WIDE_INT last_sp_adjust = 0;
- rtx last_sp_set = NULL_RTX;
- struct csa_memlist *memlist = NULL;
- rtx insn, next, set;
- struct record_stack_memrefs_data data;
- bool end_of_block = false;
-
- for (insn = BB_HEAD (bb); !end_of_block ; insn = next)
- {
- end_of_block = insn == BB_END (bb);
- next = NEXT_INSN (insn);
-
- if (! INSN_P (insn))
- continue;
-
- set = single_set_for_csa (insn);
- if (set)
- {
- rtx dest = SET_DEST (set);
- rtx src = SET_SRC (set);
-
- /* Find constant additions to the stack pointer. */
- if (dest == stack_pointer_rtx
- && GET_CODE (src) == PLUS
- && XEXP (src, 0) == stack_pointer_rtx
- && GET_CODE (XEXP (src, 1)) == CONST_INT)
- {
- HOST_WIDE_INT this_adjust = INTVAL (XEXP (src, 1));
-
- /* If we've not seen an adjustment previously, record
- it now and continue. */
- if (! last_sp_set)
- {
- last_sp_set = insn;
- last_sp_adjust = this_adjust;
- continue;
- }
-
- /* If not all recorded memrefs can be adjusted, or the
- adjustment is now too large for a constant addition,
- we cannot merge the two stack adjustments.
-
- Also we need to be careful to not move stack pointer
- such that we create stack accesses outside the allocated
- area. We can combine an allocation into the first insn,
- or a deallocation into the second insn. We can not
- combine an allocation followed by a deallocation.
-
- The only somewhat frequent occurrence of the later is when
- a function allocates a stack frame but does not use it.
- For this case, we would need to analyze rtl stream to be
- sure that allocated area is really unused. This means not
- only checking the memory references, but also all registers
- or global memory references possibly containing a stack
- frame address.
-
- Perhaps the best way to address this problem is to teach
- gcc not to allocate stack for objects never used. */
-
- /* Combine an allocation into the first instruction. */
- if (STACK_GROWS_DOWNWARD ? this_adjust <= 0 : this_adjust >= 0)
- {
- if (try_apply_stack_adjustment (last_sp_set, memlist,
- last_sp_adjust + this_adjust,
- this_adjust))
- {
- /* It worked! */
- delete_insn (insn);
- last_sp_adjust += this_adjust;
- continue;
- }
- }
-
- /* Otherwise we have a deallocation. Do not combine with
- a previous allocation. Combine into the second insn. */
- else if (STACK_GROWS_DOWNWARD
- ? last_sp_adjust >= 0 : last_sp_adjust <= 0)
- {
- if (try_apply_stack_adjustment (insn, memlist,
- last_sp_adjust + this_adjust,
- -last_sp_adjust))
- {
- /* It worked! */
- delete_insn (last_sp_set);
- last_sp_set = insn;
- last_sp_adjust += this_adjust;
- free_csa_memlist (memlist);
- memlist = NULL;
- continue;
- }
- }
-
- /* Combination failed. Restart processing from here. If
- deallocation+allocation conspired to cancel, we can
- delete the old deallocation insn. */
- if (last_sp_set && last_sp_adjust == 0)
- delete_insn (insn);
- free_csa_memlist (memlist);
- memlist = NULL;
- last_sp_set = insn;
- last_sp_adjust = this_adjust;
- continue;
- }
-
- /* Find a predecrement of exactly the previous adjustment and
- turn it into a direct store. Obviously we can't do this if
- there were any intervening uses of the stack pointer. */
- if (memlist == NULL
- && MEM_P (dest)
- && ((GET_CODE (XEXP (dest, 0)) == PRE_DEC
- && (last_sp_adjust
- == (HOST_WIDE_INT) GET_MODE_SIZE (GET_MODE (dest))))
- || (GET_CODE (XEXP (dest, 0)) == PRE_MODIFY
- && GET_CODE (XEXP (XEXP (dest, 0), 1)) == PLUS
- && XEXP (XEXP (XEXP (dest, 0), 1), 0) == stack_pointer_rtx
- && (GET_CODE (XEXP (XEXP (XEXP (dest, 0), 1), 1))
- == CONST_INT)
- && (INTVAL (XEXP (XEXP (XEXP (dest, 0), 1), 1))
- == -last_sp_adjust)))
- && XEXP (XEXP (dest, 0), 0) == stack_pointer_rtx
- && ! reg_mentioned_p (stack_pointer_rtx, src)
- && memory_address_p (GET_MODE (dest), stack_pointer_rtx)
- && validate_change (insn, &SET_DEST (set),
- replace_equiv_address (dest,
- stack_pointer_rtx),
- 0))
- {
- delete_insn (last_sp_set);
- free_csa_memlist (memlist);
- memlist = NULL;
- last_sp_set = NULL_RTX;
- last_sp_adjust = 0;
- continue;
- }
- }
-
- data.insn = insn;
- data.memlist = memlist;
- if (!CALL_P (insn) && last_sp_set
- && !for_each_rtx (&PATTERN (insn), record_stack_memrefs, &data))
- {
- memlist = data.memlist;
- continue;
- }
- memlist = data.memlist;
-
- /* Otherwise, we were not able to process the instruction.
- Do not continue collecting data across such a one. */
- if (last_sp_set
- && (CALL_P (insn)
- || reg_mentioned_p (stack_pointer_rtx, PATTERN (insn))))
- {
- if (last_sp_set && last_sp_adjust == 0)
- delete_insn (last_sp_set);
- free_csa_memlist (memlist);
- memlist = NULL;
- last_sp_set = NULL_RTX;
- last_sp_adjust = 0;
- }
- }
-
- if (last_sp_set && last_sp_adjust == 0)
- delete_insn (last_sp_set);
-}
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