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re PR target/65787 (Miscompile due to bad vector swap optimization for little endian) 

[gcc]

2015-04-17  Bill Schmidt  <wschmidt@linux.vnet.ibm.com>

	PR target/65787
	* config/rs6000/rs6000.c (rtx_is_swappable_p): Handle case where
	vec_extract operation is wrapped in a PARALLEL with a CLOBBER.
	(adjust_extract): Likewise.

[gcc/testsuite]

2015-04-17  Bill Schmidt  <wschmidt@linux.vnet.ibm.com>

	PR target/65787
	* gcc.target/powerpc/pr65787.c: New.

From-SVN: r222182
This commit is contained in:
Bill Schmidt 2015-04-17 14:50:50 +00:00 committed by William Schmidt
parent 3e1a923756
commit 6cb1b83e0f
4 changed files with 48 additions and 1 deletions
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7
gcc/ChangeLog
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@ -1,3 +1,10 @@
2015-04-17 Bill Schmidt <wschmidt@linux.vnet.ibm.com>
PR target/65787
* config/rs6000/rs6000.c (rtx_is_swappable_p): Handle case where
vec_extract operation is wrapped in a PARALLEL with a CLOBBER.
(adjust_extract): Likewise.
2015-04-17 Jakub Jelinek <jakub@redhat.com>
PR debug/65771

16
gcc/config/rs6000/rs6000.c
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@ -34204,6 +34204,17 @@ rtx_is_swappable_p (rtx op, unsigned int *special)
else
return 0;
case PARALLEL:
/* A vec_extract operation may be wrapped in a PARALLEL with a
clobber, so account for that possibility. */
if (XVECLEN (op, 0) != 2)
return 0;
if (GET_CODE (XVECEXP (op, 0, 1)) != CLOBBER)
return 0;
return rtx_is_swappable_p (XVECEXP (op, 0, 0), special);
case UNSPEC:
{
/* Various operations are unsafe for this optimization, at least
@ -34603,7 +34614,10 @@ permute_store (rtx_insn *insn)
static void
adjust_extract (rtx_insn *insn)
{
rtx src = SET_SRC (PATTERN (insn));
rtx pattern = PATTERN (insn);
if (GET_CODE (pattern) == PARALLEL)
pattern = XVECEXP (pattern, 0, 0);
rtx src = SET_SRC (pattern);
/* The vec_select may be wrapped in a vec_duplicate for a splat, so
account for that. */
rtx sel = GET_CODE (src) == VEC_DUPLICATE ? XEXP (src, 0) : src;

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2015-04-17 Bill Schmidt <wschmidt@linux.vnet.ibm.com>
PR target/65787
* gcc.target/powerpc/pr65787.c: New.
2015-04-17 Jakub Jelinek <jakub@redhat.com>
PR debug/65771

21
gcc/testsuite/gcc.target/powerpc/pr65787.c Normal file
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@ -0,0 +1,21 @@
/* { dg-do compile { target { powerpc64le-*-* } } } */
/* { dg-skip-if "do not override -mcpu" { powerpc*-*-* } { "-mcpu=*" } { "-mcpu=power8" } } */
/* { dg-options "-mcpu=power8 -O3" } */
/* { dg-final { scan-assembler "xxsldwi \[0-9\]*,\[0-9\]*,\[0-9\]*,3" } } */
/* { dg-final { scan-assembler-not "xxpermdi" } } */
/* This test verifies that a vector extract operand properly has its
lane changed by the swap optimization. Element 2 of LE corresponds
to element 1 of BE. When doublewords are swapped, this becomes
element 3 of BE, so we need to shift the vector left by 3 words
to be able to extract the correct value from BE element zero. */
typedef float v4f32 __attribute__ ((__vector_size__ (16)));
void foo (float);
extern v4f32 x, y;
int main() {
v4f32 z = x + y;
foo (z[2]);
}