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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug target/110598] [14 Regression] wrong code on llvm-14.0.6 due to memcmp being miscompiled Date: Sat, 08 Jul 2023 17:41:52 +0000 [thread overview] Message-ID: <bug-110598-4-YXJeLgvoMz@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-110598-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110598 --- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> --- Here is a C testcase: ``` #include <stdbool.h> typedef unsigned long long u64; #define MAX_SUBTARGET_WORDS 4 //[[gnu::noipa]] int notequal(const void *a, const void *b) { return __builtin_memcmp(a,b,MAX_SUBTARGET_WORDS*sizeof(u64)) != 0; } typedef struct FeatureBitset { u64 Bits[MAX_SUBTARGET_WORDS]; }FeatureBitset; __attribute__((noipa)) bool is_eq_buggy (const FeatureBitset * lf, const FeatureBitset * rf) { u64 Bits_l[MAX_SUBTARGET_WORDS]; Bits_l[0] = lf->Bits[0]&1; Bits_l[1] = 0; Bits_l[2] = 0; Bits_l[3] = 0; u64 Bits_r[MAX_SUBTARGET_WORDS]; Bits_r[0] = rf->Bits[0]&1; Bits_r[1] = 0; Bits_r[2] = 0; Bits_r[3] = 0; return !notequal(Bits_l, Bits_r); } __attribute__((noipa)) void bug(void) { FeatureBitset lf, rf; lf.Bits[0] = rf.Bits[0] = 1; lf.Bits[1] = rf.Bits[1] = 1; lf.Bits[2] = rf.Bits[2] = 1; lf.Bits[3] = rf.Bits[3] = 1; bool r = is_eq_buggy (&lf, &rf); if (!r) __builtin_trap(); } __attribute__((noipa)) int main(void) { bug(); } ``` Again uncomment the attribute on notequal, if you want to see it works without inlining of memcmp here ...
next prev parent reply other threads:[~2023-07-08 17:41 UTC|newest] Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-07-08 17:00 [Bug c++/110598] New: [14 Regression] wrong code on llvm-14.0.6 slyfox at gcc dot gnu.org 2023-07-08 17:32 ` [Bug target/110598] [14 Regression] wrong code on llvm-14.0.6 due to memcmp being miscompiled pinskia at gcc dot gnu.org 2023-07-08 17:41 ` pinskia at gcc dot gnu.org [this message] 2023-07-08 20:31 ` slyfox at gcc dot gnu.org 2023-07-09 22:34 ` roger at nextmovesoftware dot com 2023-07-12 13:13 ` cvs-commit at gcc dot gnu.org 2023-07-12 16:15 ` slyfox at gcc dot gnu.org 2023-07-12 19:42 ` roger at nextmovesoftware dot com
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