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regmove.c (fixup_match_1): Don't change an unchanging register. 

* regmove.c (fixup_match_1): Don't change an unchanging register.
        (stable_but_for_p): Renamed to:
        (stable_and_no_regs_but_for_p).  Reject unchanging registers too.
        Changed all callers.

From-SVN: r29394
This commit is contained in:
J"orn Rennecke 1999-09-14 07:39:14 +00:00 committed by Jeff Law
parent 328de7dac7
commit 18bf656fc3
2 changed files with 33 additions and 8 deletions
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7
gcc/ChangeLog
View File

@ -1,3 +1,10 @@
Tue Sep 14 01:38:52 1999 J"orn Rennecke <amylaar@cygnus.co.uk>
* regmove.c (fixup_match_1): Don't change an unchanging register.
(stable_but_for_p): Renamed to:
(stable_and_no_regs_but_for_p). Reject unchanging registers too.
Changed all callers.
Tue Sep 14 01:33:15 1999 Andreas Schwab <schwab@suse.de>
* loop.c (strength_reduce): Don't call reg_used_between_p if the

34
gcc/regmove.c
View File

@ -63,7 +63,7 @@ static int find_matches PROTO((rtx, struct match *));
static int fixup_match_1 PROTO((rtx, rtx, rtx, rtx, rtx, int, int, int, FILE *))
;
static int reg_is_remote_constant_p PROTO((rtx, rtx, rtx));
static int stable_but_for_p PROTO((rtx, rtx, rtx));
static int stable_and_no_regs_but_for_p PROTO((rtx, rtx, rtx));
static int regclass_compatible_p PROTO((int, int));
static int loop_depth;
@ -1675,6 +1675,12 @@ fixup_match_1 (insn, set, src, src_subreg, dst, backward, operand_number,
rtx src_note = find_reg_note (insn, REG_DEAD, src), dst_note;
int length, s_length, true_loop_depth;
/* 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))
@ -1691,7 +1697,7 @@ fixup_match_1 (insn, set, src, src_subreg, dst, backward, operand_number,
&& XEXP (SET_SRC (set), 0) == src
&& GET_CODE (XEXP (SET_SRC (set), 1)) == CONST_INT)
insn_const = INTVAL (XEXP (SET_SRC (set), 1));
else if (! stable_but_for_p (SET_SRC (set), src, dst))
else if (! stable_and_no_regs_but_for_p (SET_SRC (set), src, dst))
return 0;
else
/* We might find a src_note while scanning. */
@ -2113,10 +2119,16 @@ fixup_match_1 (insn, set, src, src_subreg, dst, backward, operand_number,
}
/* return nonzero if X is stable but for mentioning SRC or mentioning /
changing DST . If in doubt, presume it is unstable. */
/* return nonzero if X is stable and mentions no regsiters but for
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. */
static int
stable_but_for_p (x, src, dst)
stable_and_no_regs_but_for_p (x, src, dst)
rtx x, src, dst;
{
RTX_CODE code = GET_CODE (x);
@ -2127,13 +2139,19 @@ stable_but_for_p (x, src, dst)
int i;
const char *fmt = GET_RTX_FORMAT (code);
for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
if (fmt[i] == 'e' && ! stable_but_for_p (XEXP (x, i), src, dst))
if (fmt[i] == 'e'
&& ! stable_and_no_regs_but_for_p (XEXP (x, i), src, dst))
return 0;
return 1;
}
case 'o':
if (x == src || x == dst)
return 1;
if (code == REG)
return x == src || x == dst;
/* If this is a MEM, look inside - there might be a register hidden in
the address of an unchanging MEM. */
if (code == MEM
&& ! stable_and_no_regs_but_for_p (XEXP (x, 0), src, dst))
return 0;
/* fall through */
default:
return ! rtx_unstable_p (x);