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From: "slyfox at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug target/115161] [15 Regression] highway-1.0.7 miscompilation of some SSE2 intrinsics Date: Thu, 23 May 2024 10:39:22 +0000 [thread overview] Message-ID: <bug-115161-4-Xmsr8UYWPl@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-115161-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115161 --- Comment #21 from Sergei Trofimovich <slyfox at gcc dot gnu.org> --- Shrunk the example down to a single simpler function while preserving the original masking intent: ```c cat bug.cc #include <stdint.h> #include <string.h> #include <emmintrin.h> __attribute__((noipa)) static void assert_eq_p(void * l, void * r) { char lb[16]; char rb[16]; __builtin_memcpy(lb, l, 16); __builtin_memcpy(rb, r, 16); if (__builtin_memcmp(lb, rb, 16) != 0) __builtin_trap(); } __attribute__((noipa)) static void assert_eq(__m128i l, __m128i r) { assert_eq_p(&l, &r); } int main() { const __m128i su = _mm_set1_epi32(0x4f800000); const __m128 sf = _mm_castsi128_ps(su); const __m128 overflow_mask_f32 = _mm_cmpge_ps(sf, _mm_set1_ps(2147483648.0f)); const __m128i overflow_mask = _mm_castps_si128(overflow_mask_f32); const __m128i conv = _mm_cvttps_epi32(sf); // overflows const __m128i yes = _mm_set1_epi32(INT32_MAX); const __m128i a = _mm_and_si128(overflow_mask, yes); const __m128i na = _mm_andnot_si128(overflow_mask, conv); const __m128i conv_masked = _mm_or_si128(a, na); const __m128i actual = _mm_cmpeq_epi32(conv_masked, _mm_set1_epi32(INT32_MAX)); const __m128i expected = _mm_set1_epi32(-1); assert_eq(expected, actual); } ``` The discrepancy: Ok: $ /tmp/gb/gcc/xg++ -Wall -B/tmp/gb/gcc bug.cc -o bug -O0 && ./bug Bad: $ /tmp/gb/gcc/xg++ -Wall -B/tmp/gb/gcc bug.cc -o bug -O2 && ./bug Illegal instruction (core dumped)
next prev parent reply other threads:[~2024-05-23 10:39 UTC|newest] Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top 2024-05-20 10:07 [Bug target/115161] New: " slyfox at gcc dot gnu.org 2024-05-20 11:26 ` [Bug target/115161] " slyfox at gcc dot gnu.org 2024-05-20 14:48 ` roger at nextmovesoftware dot com 2024-05-20 22:08 ` slyfox at gcc dot gnu.org 2024-05-21 6:41 ` rguenth at gcc dot gnu.org 2024-05-21 14:53 ` jakub at gcc dot gnu.org 2024-05-21 15:02 ` jakub at gcc dot gnu.org 2024-05-21 15:13 ` jakub at gcc dot gnu.org 2024-05-21 15:40 ` amonakov at gcc dot gnu.org 2024-05-21 15:50 ` slyfox at gcc dot gnu.org 2024-05-21 15:51 ` jakub at gcc dot gnu.org 2024-05-21 16:07 ` jakub at gcc dot gnu.org 2024-05-22 1:06 ` liuhongt at gcc dot gnu.org 2024-05-22 1:13 ` pinskia at gcc dot gnu.org 2024-05-22 7:27 ` jakub at gcc dot gnu.org 2024-05-22 7:41 ` slyfox at gcc dot gnu.org 2024-05-22 7:43 ` slyfox at gcc dot gnu.org 2024-05-22 7:52 ` liuhongt at gcc dot gnu.org 2024-05-22 8:03 ` jakub at gcc dot gnu.org 2024-05-22 8:22 ` amonakov at gcc dot gnu.org 2024-05-22 8:26 ` jakub at gcc dot gnu.org 2024-05-22 8:49 ` amonakov at gcc dot gnu.org 2024-05-23 10:39 ` slyfox at gcc dot gnu.org [this message] 2024-05-24 22:00 ` slyfox at gcc dot gnu.org 2024-05-25 17:15 ` amonakov at gcc dot gnu.org 2024-05-25 18:44 ` slyfox at gcc dot gnu.org 2024-05-27 0:47 ` [Bug target/115161] highway-1.0.7 miscompilation of _mm_cvttps_epi32(): invalid result assumed liuhongt at gcc dot gnu.org 2024-06-05 4:09 ` cvs-commit at gcc dot gnu.org 2024-06-05 9:13 ` slyfox at gcc dot gnu.org 2024-06-17 8:17 ` cvs-commit at gcc dot gnu.org
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