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| author | Jakub Jelinek <jakub@redhat.com> | 2022-06-21 11:40:16 +0200 |
|---|---|---|
| committer | Jakub Jelinek <jakub@redhat.com> | 2022-06-28 17:37:37 +0200 |
| commit | 9e72a522dd9f835dd159fe3aff493eee001be0d4 (patch) | |
| tree | f06f8c781912de3b9767e54a1c1fb9080c2244ca /gcc/ifcvt.cc | |
| parent | d068623e5b109e635e2ec2acfcf15e7c50c7f15c (diff) | |
| download | gcc-9e72a522dd9f835dd159fe3aff493eee001be0d4.zip gcc-9e72a522dd9f835dd159fe3aff493eee001be0d4.tar.gz gcc-9e72a522dd9f835dd159fe3aff493eee001be0d4.tar.bz2 | |
ifcvt: Don't introduce trapping or faulting reads in noce_try_sign_mask [PR106032]
noce_try_sign_mask as documented will optimize
if (c < 0)
x = t;
else
x = 0;
into x = (c >> bitsm1) & t;
The optimization is done if either t is unconditional
(e.g. for
x = t;
if (c >= 0)
x = 0;
) or if it is cheap. We already check that t doesn't have side-effects,
but if t is conditional, we need to punt also if it may trap or fault,
as we make it unconditional.
I've briefly skimmed other noce_try* optimizations and didn't find one that
would suffer from the same problem.
2022-06-21 Jakub Jelinek <jakub@redhat.com>
PR rtl-optimization/106032
* ifcvt.cc (noce_try_sign_mask): Punt if !t_unconditional, and
t may_trap_or_fault_p, even if it is cheap.
* gcc.c-torture/execute/pr106032.c: New test.
(cherry picked from commit a0c30fe3b888f20215f3e040d21b62b603804ca9)
Diffstat (limited to 'gcc/ifcvt.cc')
| -rw-r--r-- | gcc/ifcvt.cc | 15 |
1 files changed, 8 insertions, 7 deletions
diff --git a/gcc/ifcvt.cc b/gcc/ifcvt.cc index b983e87..e007b17 100644 --- a/gcc/ifcvt.cc +++ b/gcc/ifcvt.cc @@ -2833,18 +2833,19 @@ noce_try_sign_mask (struct noce_if_info *if_info) return FALSE; /* This is only profitable if T is unconditionally executed/evaluated in the - original insn sequence or T is cheap. The former happens if B is the - non-zero (T) value and if INSN_B was taken from TEST_BB, or there was no - INSN_B which can happen for e.g. conditional stores to memory. For the - cost computation use the block TEST_BB where the evaluation will end up - after the transformation. */ + original insn sequence or T is cheap and can't trap or fault. The former + happens if B is the non-zero (T) value and if INSN_B was taken from + TEST_BB, or there was no INSN_B which can happen for e.g. conditional + stores to memory. For the cost computation use the block TEST_BB where + the evaluation will end up after the transformation. */ t_unconditional = (t == if_info->b && (if_info->insn_b == NULL_RTX || BLOCK_FOR_INSN (if_info->insn_b) == if_info->test_bb)); if (!(t_unconditional - || (set_src_cost (t, mode, if_info->speed_p) - < COSTS_N_INSNS (2)))) + || ((set_src_cost (t, mode, if_info->speed_p) + < COSTS_N_INSNS (2)) + && !may_trap_or_fault_p (t)))) return FALSE; if (!noce_can_force_operand (t)) |