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(try_combine): Don't make a MULT if none of the insns in our input had one.

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From-SVN: r7803
This commit is contained in:
Richard Kenner 1994-07-28 07:11:09 -04:00
parent 98310eaac7
commit df7d75de69
1 changed files with 28 additions and 10 deletions
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38
gcc/combine.c
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@ -1203,6 +1203,8 @@ try_combine (i3, i2, i1)
rtx new_i3_notes, new_i2_notes;
/* Notes that we substituted I3 into I2 instead of the normal case. */
int i3_subst_into_i2 = 0;
/* Notes that I1, I2 or I3 is a MULT operation. */
int have_mult = 0;
int maxreg;
rtx temp;
@ -1392,6 +1394,15 @@ try_combine (i3, i2, i1)
return 0;
}
/* See if any of the insns is a MULT operation. Unless one is, we will
reject a combination that is, since it must be slower. Be conservative
here. */
if (GET_CODE (i2src) == MULT
|| (i1 != 0 && GET_CODE (i1src) == MULT)
|| (GET_CODE (PATTERN (i3)) == SET
&& GET_CODE (SET_SRC (PATTERN (i3))) == MULT))
have_mult = 1;
/* If I3 has an inc, then give up if I1 or I2 uses the reg that is inc'd.
We used to do this EXCEPT in one case: I3 has a post-inc in an
output operand. However, that exception can give rise to insns like
@ -1601,7 +1612,11 @@ try_combine (i3, i2, i1)
really no reason to). */
|| max_reg_num () != maxreg
/* Fail if we couldn't do something and have a CLOBBER. */
|| GET_CODE (newpat) == CLOBBER)
|| GET_CODE (newpat) == CLOBBER
/* Fail if this new pattern is a MULT and we didn't have one before
at the outer level. */
|| (GET_CODE (newpat) == SET && GET_CODE (SET_SRC (newpat)) == MULT
&& ! have_mult))
{
undo_all ();
return 0;
@ -1804,13 +1819,14 @@ try_combine (i3, i2, i1)
&& ! reg_referenced_p (i2dest, newpat))
{
rtx newdest = i2dest;
enum rtx_code split_code = GET_CODE (*split);
enum machine_mode split_mode = GET_MODE (*split);
/* Get NEWDEST as a register in the proper mode. We have already
validated that we can do this. */
if (GET_MODE (i2dest) != GET_MODE (*split)
&& GET_MODE (*split) != VOIDmode)
if (GET_MODE (i2dest) != split_mode && split_mode != VOIDmode)
{
newdest = gen_rtx (REG, GET_MODE (*split), REGNO (i2dest));
newdest = gen_rtx (REG, split_mode, REGNO (i2dest));
if (REGNO (i2dest) >= FIRST_PSEUDO_REGISTER)
SUBST (regno_reg_rtx[REGNO (i2dest)], newdest);
@ -1819,25 +1835,27 @@ try_combine (i3, i2, i1)
/* If *SPLIT is a (mult FOO (const_int pow2)), convert it to
an ASHIFT. This can occur if it was inside a PLUS and hence
appeared to be a memory address. This is a kludge. */
if (GET_CODE (*split) == MULT
if (split_code == MULT
&& GET_CODE (XEXP (*split, 1)) == CONST_INT
&& (i = exact_log2 (INTVAL (XEXP (*split, 1)))) >= 0)
SUBST (*split, gen_rtx_combine (ASHIFT, GET_MODE (*split),
SUBST (*split, gen_rtx_combine (ASHIFT, split_mode,
XEXP (*split, 0), GEN_INT (i)));
#ifdef INSN_SCHEDULING
/* If *SPLIT is a paradoxical SUBREG, when we split it, it should
be written as a ZERO_EXTEND. */
if (GET_CODE (*split) == SUBREG
&& GET_CODE (SUBREG_REG (*split)) == MEM)
SUBST (*split, gen_rtx_combine (ZERO_EXTEND, GET_MODE (*split),
if (split_code == SUBREG && GET_CODE (SUBREG_REG (*split)) == MEM)
SUBST (*split, gen_rtx_combine (ZERO_EXTEND, split_mode,
XEXP (*split, 0)));
#endif
newi2pat = gen_rtx_combine (SET, VOIDmode, newdest, *split);
SUBST (*split, newdest);
i2_code_number = recog_for_combine (&newi2pat, i2, &new_i2_notes);
if (i2_code_number >= 0)
/* If the split point was a MULT and we didn't have one before,
don't use one now. */
if (i2_code_number >= 0 && ! (split_code == MULT && ! have_mult))
insn_code_number = recog_for_combine (&newpat, i3, &new_i3_notes);
}
}