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| author | Jakub Jelinek <jakub@redhat.com> | 2024-04-19 08:47:53 +0200 |
|---|---|---|
| committer | Jakub Jelinek <jakub@redhat.com> | 2024-06-11 12:35:37 +0200 |
| commit | 7d0673575aba5dfb41022897a882b9c386c332f4 (patch) | |
| tree | 1f246d6c12431fe94e69ef23c4b6f98a1825da76 | |
| parent | b3ef00f8b8d577d7b62cea36c13cf087a3b13d0c (diff) | |
| download | gcc-7d0673575aba5dfb41022897a882b9c386c332f4.zip gcc-7d0673575aba5dfb41022897a882b9c386c332f4.tar.gz gcc-7d0673575aba5dfb41022897a882b9c386c332f4.tar.bz2 | |
rtlanal: Fix set_noop_p for volatile loads or stores [PR114768]
On the following testcase, combine propagates the mem/v load into mem store
with the same address and then removes it, because noop_move_p says it is a
no-op move. If it was the other way around, i.e. mem/v store and mem load,
or both would be mem/v, it would be kept.
The problem is that rtx_equal_p never checks any kind of flags on the rtxes
(and I think it would be quite dangerous to change it at this point), and
set_noop_p checks side_effects_p on just one of the operands, not both.
In the MEM <- MEM set, it only checks it on the destination, in
store to ZERO_EXTRACT only checks it on the source.
The following patch adds the missing side_effects_p checks.
2024-04-19 Jakub Jelinek <jakub@redhat.com>
PR rtl-optimization/114768
* rtlanal.cc (set_noop_p): Don't return true for MEM <- MEM
sets if src has side-effects or for stores into ZERO_EXTRACT
if ZERO_EXTRACT operand has side-effects.
* gcc.dg/pr114768.c: New test.
(cherry picked from commit 9f295847a9c32081bdd0fe908ffba58e830a24fb)
| -rw-r--r-- | gcc/rtlanal.cc | 11 | ||||
| -rw-r--r-- | gcc/testsuite/gcc.dg/pr114768.c | 10 |
2 files changed, 17 insertions, 4 deletions
diff --git a/gcc/rtlanal.cc b/gcc/rtlanal.cc index 78a740c..5ba5e4a 100644 --- a/gcc/rtlanal.cc +++ b/gcc/rtlanal.cc @@ -1639,12 +1639,15 @@ set_noop_p (const_rtx set) return 1; if (MEM_P (dst) && MEM_P (src)) - return rtx_equal_p (dst, src) && !side_effects_p (dst); + return (rtx_equal_p (dst, src) + && !side_effects_p (dst) + && !side_effects_p (src)); if (GET_CODE (dst) == ZERO_EXTRACT) - return rtx_equal_p (XEXP (dst, 0), src) - && !BITS_BIG_ENDIAN && XEXP (dst, 2) == const0_rtx - && !side_effects_p (src); + return (rtx_equal_p (XEXP (dst, 0), src) + && !BITS_BIG_ENDIAN && XEXP (dst, 2) == const0_rtx + && !side_effects_p (src) + && !side_effects_p (XEXP (dst, 0))); if (GET_CODE (dst) == STRICT_LOW_PART) dst = XEXP (dst, 0); diff --git a/gcc/testsuite/gcc.dg/pr114768.c b/gcc/testsuite/gcc.dg/pr114768.c new file mode 100644 index 0000000..ffe3b36 --- /dev/null +++ b/gcc/testsuite/gcc.dg/pr114768.c @@ -0,0 +1,10 @@ +/* PR rtl-optimization/114768 */ +/* { dg-do compile } */ +/* { dg-options "-O2 -fdump-rtl-final" } */ +/* { dg-final { scan-rtl-dump "\\\(mem/v:" "final" } } */ + +void +foo (int *p) +{ + *p = *(volatile int *) p; +} |