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PR target/106278: Keep REG_EQUAL notes consistent during TImode STV on x86_64. 

This patch resolves PR target/106278 a regression on x86_64 caused by my
recent TImode STV improvements.  Now that TImode STV can handle comparisons
such as "(set (regs:CC) (compare:CC (reg:TI) ...))" the convert_insn method
sensibly checks that the mode of the SET_DEST is TImode before setting
it to V1TImode [to avoid V1TImode appearing on the hard reg CC_FLAGS.

Hence the current code looks like:

      if (GET_MODE (dst) == TImode)
 	{
 	  tmp = find_reg_equal_equiv_note (insn);
 	  if (tmp && GET_MODE (XEXP (tmp, 0)) == TImode)
 	    PUT_MODE (XEXP (tmp, 0), V1TImode);
	  PUT_MODE (dst, V1TImode);
	  fix_debug_reg_uses (dst);
 	}
      break;

which checks GET_MODE (dst) before calling PUT_MODE, and when a
change is made updating the REG_EQUAL_NOTE tmp if it exists.

The logical flaw (oversight) is that due to RTL sharing, the destination
of this set may already have been updated to V1TImode, as this chain is
being converted, but we still need to update any REG_EQUAL_NOTE that
still has TImode.  Hence the correct code is actually:

      if (GET_MODE (dst) == TImode)
 	{
	  PUT_MODE (dst, V1TImode);
	  fix_debug_reg_uses (dst);
	}
      if (GET_MODE (dst) == V1TImode)
	{
 	  tmp = find_reg_equal_equiv_note (insn);
 	  if (tmp && GET_MODE (XEXP (tmp, 0)) == TImode)
 	    PUT_MODE (XEXP (tmp, 0), V1TImode);
 	}
      break;

While fixing this behavior, I noticed I had some indentation whitespace
issues and some vestigial dead code in this function/method that I've
taken the liberty of cleaning up (as obvious) in this patch.

2022-07-15  Roger Sayle  <roger@nextmovesoftware.com>

gcc/ChangeLog
	PR target/106278
	* config/i386/i386-features.cc (general_scalar_chain::convert_insn):
	Fix indentation whitespace.
	(timode_scalar_chain::fix_debug_reg_uses): Likewise.
	(timode_scalar_chain::convert_insn): Delete dead code.
	Update TImode REG_EQUAL_NOTE even if the SET_DEST is already V1TI.
	Fix indentation whitespace.
	(convertible_comparison_p): Likewise.
	(timode_scalar_to_vector_candidate_p): Likewise.

gcc/testsuite/ChangeLog
	* gcc.dg/pr106278.c: New test case.
This commit is contained in:
Roger Sayle 2022-07-15 14:39:28 +01:00
parent 3aab916f4f
commit 2fd215b03e
2 changed files with 38 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

34
gcc/config/i386/i386-features.cc
View File

@ -1054,13 +1054,13 @@ general_scalar_chain::convert_insn (rtx_insn *insn)
else if (REG_P (dst) && GET_MODE (dst) == smode)
{
/* Replace the definition with a SUBREG to the definition we
use inside the chain. */
use inside the chain. */
rtx *vdef = defs_map.get (dst);
if (vdef)
dst = *vdef;
dst = gen_rtx_SUBREG (vmode, dst, 0);
/* IRA doesn't like to have REG_EQUAL/EQUIV notes when the SET_DEST
is a non-REG_P. So kill those off. */
is a non-REG_P. So kill those off. */
rtx note = find_reg_equal_equiv_note (insn);
if (note)
remove_note (insn, note);
@ -1246,7 +1246,7 @@ timode_scalar_chain::fix_debug_reg_uses (rtx reg)
{
rtx_insn *insn = DF_REF_INSN (ref);
/* Make sure the next ref is for a different instruction,
so that we're not affected by the rescan. */
so that we're not affected by the rescan. */
next = DF_REF_NEXT_REG (ref);
while (next && DF_REF_INSN (next) == insn)
next = DF_REF_NEXT_REG (next);
@ -1336,21 +1336,19 @@ timode_scalar_chain::convert_insn (rtx_insn *insn)
rtx dst = SET_DEST (def_set);
rtx tmp;
if (MEM_P (dst) && !REG_P (src))
{
/* There are no scalar integer instructions and therefore
temporary register usage is required. */
}
switch (GET_CODE (dst))
{
case REG:
if (GET_MODE (dst) == TImode)
{
PUT_MODE (dst, V1TImode);
fix_debug_reg_uses (dst);
}
if (GET_MODE (dst) == V1TImode)
{
tmp = find_reg_equal_equiv_note (insn);
if (tmp && GET_MODE (XEXP (tmp, 0)) == TImode)
PUT_MODE (XEXP (tmp, 0), V1TImode);
PUT_MODE (dst, V1TImode);
fix_debug_reg_uses (dst);
}
break;
case MEM:
@ -1410,8 +1408,8 @@ timode_scalar_chain::convert_insn (rtx_insn *insn)
if (MEM_P (dst))
{
tmp = gen_reg_rtx (V1TImode);
emit_insn_before (gen_rtx_SET (tmp, src), insn);
src = tmp;
emit_insn_before (gen_rtx_SET (tmp, src), insn);
src = tmp;
}
break;
@ -1434,8 +1432,8 @@ timode_scalar_chain::convert_insn (rtx_insn *insn)
if (MEM_P (dst))
{
tmp = gen_reg_rtx (V1TImode);
emit_insn_before (gen_rtx_SET (tmp, src), insn);
src = tmp;
emit_insn_before (gen_rtx_SET (tmp, src), insn);
src = tmp;
}
break;
@ -1448,8 +1446,8 @@ timode_scalar_chain::convert_insn (rtx_insn *insn)
if (MEM_P (dst))
{
tmp = gen_reg_rtx (V1TImode);
emit_insn_before (gen_rtx_SET (tmp, src), insn);
src = tmp;
emit_insn_before (gen_rtx_SET (tmp, src), insn);
src = tmp;
}
break;
@ -1585,7 +1583,7 @@ convertible_comparison_p (rtx_insn *insn, enum machine_mode mode)
/* *cmp<dwi>_doubleword. */
if ((CONST_INT_P (op1)
|| ((REG_P (op1) || MEM_P (op1))
&& GET_MODE (op1) == mode))
&& GET_MODE (op1) == mode))
&& (CONST_INT_P (op2)
|| ((REG_P (op2) || MEM_P (op2))
&& GET_MODE (op2) == mode)))
@ -1745,7 +1743,7 @@ timode_scalar_to_vector_candidate_p (rtx_insn *insn)
if (GET_MODE (dst) != TImode
|| (GET_MODE (src) != TImode
&& !CONST_SCALAR_INT_P (src)))
&& !CONST_SCALAR_INT_P (src)))
return false;
if (!REG_P (dst) && !MEM_P (dst))

22
gcc/testsuite/gcc.dg/pr106278.c Normal file
View File

@ -0,0 +1,22 @@
/* { dg-do compile } */
/* { dg-options "-O2" } */
void __assert_fail();
struct a {
int b;
int c;
int d;
int : 2;
};
int e, f;
struct a g, i;
const struct a h;
int main() {
struct a j;
g = h;
if (e)
__assert_fail();
if (f)
j = h;
i = j;
return 0;
}