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* [Bug tree-optimization/111739] New: incorrect code with PGO enabled @ 2023-10-09 12:50 iamanonymous.cs at gmail dot com 2023-10-09 13:17 ` [Bug tree-optimization/111739] " rguenth at gcc dot gnu.org ` (2 more replies) 0 siblings, 3 replies; 4+ messages in thread From: iamanonymous.cs at gmail dot com @ 2023-10-09 12:50 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111739 Bug ID: 111739 Summary: incorrect code with PGO enabled Product: gcc Version: 14.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: iamanonymous.cs at gmail dot com Target Milestone: --- ******************************************************************************* OS and Platform: $ uname -a: Linux ubuntu 4.15.0-213-generic #224-Ubuntu SMP Mon Jun 19 13:30:12 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux ******************************************************************************* gcc version: $ gcc -v Using built-in specs. COLLECT_GCC=/root/gcc_set/new_gcc/bin/gcc COLLECT_LTO_WRAPPER=/root/gcc_set/new_gcc/libexec/gcc/x86_64-pc-linux-gnu/14.0.0/lto-wrapper Target: x86_64-pc-linux-gnu Configured with: ../gcc/configure --prefix=/root/gcc_set/new_gcc --with-gmp=/root/build_essential --with-mpfr=/root/build_essential --with-mpc=/root/build_essential --enable-languages=c,c++ --disable-multilib Thread model: posix Supported LTO compression algorithms: zlib gcc version 14.0.0 20230719 (experimental) (GCC) git version:85da0b40538fb0d17d89de1e7905984668e3dfef ******************************************************************************* Program: $ cat a.c c, d, e, a; union { int f; short g } h; *j = &h; k(short l, short m) { return m == 0 || l && m == 1 ?: l / m; } n(l) { return c == 0 ?: l / c; } main() { a = n(h.f++); *j = 0; int i = 0; for (; i < 2; i++) d = k(h.g || 0, 59376); short *b = &h; *b ^= e; printf("%d\n", h); } ******************************************************************************* Command Lines: # The profile directory is used to save profile information. $ gcc -O3 -w -fprofile-generate=profile a.c -o a.out $ ./a.out 0 $ gcc -O3 -w -fprofile-use=profile -Wno-missing-profile -fprofile-correction a.c -o a.out $ ./a.out 1 We can found that, the output of the executable is incorrect when the profile guided optimization is enabled. ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/111739] incorrect code with PGO enabled 2023-10-09 12:50 [Bug tree-optimization/111739] New: incorrect code with PGO enabled iamanonymous.cs at gmail dot com @ 2023-10-09 13:17 ` rguenth at gcc dot gnu.org 2023-10-09 13:34 ` iamanonymous.cs at gmail dot com 2023-10-19 1:37 ` pinskia at gcc dot gnu.org 2 siblings, 0 replies; 4+ messages in thread From: rguenth at gcc dot gnu.org @ 2023-10-09 13:17 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111739 Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords| |wrong-code Last reconfirmed| |2023-10-09 Status|UNCONFIRMED |NEW Ever confirmed|0 |1 --- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> --- Confirmed with r14-4302 and also with the head of the GCC 13 branch. It helps if you can produce proper ISO C without implicit int and like. ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/111739] incorrect code with PGO enabled 2023-10-09 12:50 [Bug tree-optimization/111739] New: incorrect code with PGO enabled iamanonymous.cs at gmail dot com 2023-10-09 13:17 ` [Bug tree-optimization/111739] " rguenth at gcc dot gnu.org @ 2023-10-09 13:34 ` iamanonymous.cs at gmail dot com 2023-10-19 1:37 ` pinskia at gcc dot gnu.org 2 siblings, 0 replies; 4+ messages in thread From: iamanonymous.cs at gmail dot com @ 2023-10-09 13:34 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111739 --- Comment #2 from Anonymous <iamanonymous.cs at gmail dot com> --- (In reply to Richard Biener from comment #1) > Confirmed with r14-4302 and also with the head of the GCC 13 branch. > > It helps if you can produce proper ISO C without implicit int and like. Thank you for confirming the bug. Moving forward, we will ensure that the code does not rely on implicit integer types. ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/111739] incorrect code with PGO enabled 2023-10-09 12:50 [Bug tree-optimization/111739] New: incorrect code with PGO enabled iamanonymous.cs at gmail dot com 2023-10-09 13:17 ` [Bug tree-optimization/111739] " rguenth at gcc dot gnu.org 2023-10-09 13:34 ` iamanonymous.cs at gmail dot com @ 2023-10-19 1:37 ` pinskia at gcc dot gnu.org 2 siblings, 0 replies; 4+ messages in thread From: pinskia at gcc dot gnu.org @ 2023-10-19 1:37 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111739 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|NEW |RESOLVED Resolution|--- |INVALID --- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> --- The code is undefined for alias reasons: union { int f; short g } h; *j = &h; ... a = n(h.f++); *j = 0; ... for (; i < 2; i++) d = k(h.g || 0, 59376); short *b = &h; *b ^= e; printf("%d\n", h); ``` In the case of profiling, we are able to optimize away the short load from h in: *b ^= e; and point it back to the store from `h.f++` and miss the store via *j. Once you add -fno-strict-aliasing the testcase starts to work. ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2023-10-19 1:37 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2023-10-09 12:50 [Bug tree-optimization/111739] New: incorrect code with PGO enabled iamanonymous.cs at gmail dot com 2023-10-09 13:17 ` [Bug tree-optimization/111739] " rguenth at gcc dot gnu.org 2023-10-09 13:34 ` iamanonymous.cs at gmail dot com 2023-10-19 1:37 ` pinskia at gcc dot gnu.org
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