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From: "kristerw at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/106523] New: forwprop miscompile Date: Thu, 04 Aug 2022 10:23:41 +0000 [thread overview] Message-ID: <bug-106523-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106523 Bug ID: 106523 Summary: forwprop miscompile Product: gcc Version: 13.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: kristerw at gcc dot gnu.org Target Milestone: --- The function f7 from testsuite/c-c++-common/rotate-2.c is miscompiled by forwprop. This can be seen by running the function as __attribute__((noinline)) unsigned char f7 (unsigned char x, unsigned int y) { unsigned int t = x; return (t << y) | (t >> ((-y) & 7)); } int main (void) { volatile unsigned char x = 152; volatile unsigned int y = 19; if (f7(x, y) != 4) __builtin_abort (); return 0; } This fails at -O1 and higher optimization levels. What is happening here is that forwprop1 has optimized the function to _10 = x_7(D) r<< y_9(D); return _10;
next reply other threads:[~2022-08-04 10:23 UTC|newest] Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-08-04 10:23 kristerw at gcc dot gnu.org [this message] 2022-08-04 10:48 ` [Bug tree-optimization/106523] [10/11/12/13 Regression] " rguenth at gcc dot gnu.org 2022-08-09 12:40 ` marxin at gcc dot gnu.org 2023-01-16 12:27 ` jakub at gcc dot gnu.org 2023-01-16 12:54 ` jakub at gcc dot gnu.org 2023-01-16 17:43 ` jakub at gcc dot gnu.org 2023-01-17 11:19 ` cvs-commit at gcc dot gnu.org 2023-01-17 11:20 ` [Bug tree-optimization/106523] [10/11/12 " jakub at gcc dot gnu.org 2023-01-17 23:46 ` kristerw at gcc dot gnu.org 2023-02-10 17:47 ` cvs-commit at gcc dot gnu.org 2023-02-10 17:56 ` [Bug tree-optimization/106523] [10/11 " jakub at gcc dot gnu.org 2023-07-07 10:43 ` [Bug tree-optimization/106523] [11 " rguenth at gcc dot gnu.org
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