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From: Jakub Jelinek <jakub@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org Subject: [gcc r13-4081] ragen-op-float: Fix up float_binary_op_range_finish [PR107668] Date: Wed, 16 Nov 2022 06:36:26 +0000 (GMT) [thread overview] Message-ID: <20221116063626.2A8EC3954C5D@sourceware.org> (raw) https://gcc.gnu.org/g:7c6cd9c05efca29a1a9635b81c86cbad25bbdbbe commit r13-4081-g7c6cd9c05efca29a1a9635b81c86cbad25bbdbbe Author: Jakub Jelinek <jakub@redhat.com> Date: Wed Nov 16 07:30:07 2022 +0100 ragen-op-float: Fix up float_binary_op_range_finish [PR107668] The following testcase ICEs, because when !HONOR_NANS but HONOR_SIGNED_ZEROS, if we see lhs = op1 * op2; and know that lhs is [-0.0, 0.0] and op2 is [0.0, 0.0], the division of these two yields UNDEFINED and clear_nan () on it fails an assert. With HONOR_NANS it would actually result in a known NAN, but when NANs aren't honored, we clear the NAN bits. Now, for the above case we actually don't know anything about the op1 range (except that it isn't a NAN/INF because of !HONOR_NANS !HONOR_INFINITIES), so I think the best is just to return VARYING for the case we get UNDEFINED as well. If we want, the op[12]_range methods perhaps can handle the corner cases earlier separately, say for lhs [0.0, 0.0] and op2 [0.0, 0.0] when HONOR_SIGNED_ZEROS this would be just [0.0, MAX]. 2022-11-16 Jakub Jelinek <jakub@redhat.com> PR tree-optimization/107668 * range-op-float.cc (float_binary_op_range_finish): Set VARYING also when r is UNDEFINED. * gcc.dg/ubsan/pr107668.c: New test. Diff: --- gcc/range-op-float.cc | 3 ++- gcc/testsuite/gcc.dg/ubsan/pr107668.c | 12 ++++++++++++ 2 files changed, 14 insertions(+), 1 deletion(-) diff --git a/gcc/range-op-float.cc b/gcc/range-op-float.cc index 53a0928c6aa..0c4ec8dd178 100644 --- a/gcc/range-op-float.cc +++ b/gcc/range-op-float.cc @@ -1891,8 +1891,9 @@ float_binary_op_range_finish (bool ret, frange &r, tree type, // or the reverse operation introduced a known NAN. // Say for lhs = op1 * op2 if lhs is [-0, +0] and op2 is too, // 0 / 0 is known NAN. Just punt in that case. + // If NANs aren't honored, we get for 0 / 0 UNDEFINED, so punt as well. // Or if lhs is a known NAN, we also don't know anything. - if (r.known_isnan () || lhs.known_isnan ()) + if (r.known_isnan () || lhs.known_isnan () || r.undefined_p ()) { r.set_varying (type); return true; diff --git a/gcc/testsuite/gcc.dg/ubsan/pr107668.c b/gcc/testsuite/gcc.dg/ubsan/pr107668.c new file mode 100644 index 00000000000..e94d6cdb530 --- /dev/null +++ b/gcc/testsuite/gcc.dg/ubsan/pr107668.c @@ -0,0 +1,12 @@ +/* PR tree-optimization/107668 */ +/* { dg-do compile } */ +/* { dg-options "-ffast-math -fno-associative-math -fsanitize=float-cast-overflow -fno-guess-branch-probability -fsigned-zeros" } */ + +_Complex int c; +int i; + +void +foo (void) +{ + c /= (_Complex) i; +}
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