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* [Bug tree-optimization/115004] New: [11/12/13/14/15 Regression] Missed optimization for Dead Code Elimination @ 2024-05-09 9:06 652023330028 at smail dot nju.edu.cn 2024-05-09 16:40 ` [Bug tree-optimization/115004] " pinskia at gcc dot gnu.org ` (2 more replies) 0 siblings, 3 replies; 4+ messages in thread From: 652023330028 at smail dot nju.edu.cn @ 2024-05-09 9:06 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115004 Bug ID: 115004 Summary: [11/12/13/14/15 Regression] Missed optimization for Dead Code Elimination Product: gcc Version: 15.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: 652023330028 at smail dot nju.edu.cn Target Milestone: --- Hello, we noticed that the code below can be optimized by Dead Code Elimination, but gcc -O3 missed it. This is a regression from GCC-8.1. https://godbolt.org/z/7e64e56Mq int m; void fn(signed char p1, short p2, signed char p3_1, signed char p3_2, short p4, unsigned char p5) { if( (signed char)((p4 | 0) && (p1 || p2) || p5 || p3_1 && p5) - (signed char)((p4 | 0) && (p1 || p2) || p5 || p3_2 && p5) ) { m=1; } } GCC -O3: fn(signed char, short, signed char, signed char, short, unsigned char): test r8w, r8w je .L1 test dil, dil setne al test si, si setne dl or eax, edx test r9b, r9b jne .L6 .L1: ret .L6: test al, al jne .L1 test r9b, r9b jne .L1 mov DWORD PTR m[rip], 1 ret Expected code (GCC-7.5): fn(signed char, short, signed char, signed char, short, unsigned char): rep ret Thank you very much for your time and effort! We look forward to hearing from you. ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/115004] [11/12/13/14/15 Regression] Missed optimization for Dead Code Elimination 2024-05-09 9:06 [Bug tree-optimization/115004] New: [11/12/13/14/15 Regression] Missed optimization for Dead Code Elimination 652023330028 at smail dot nju.edu.cn @ 2024-05-09 16:40 ` pinskia at gcc dot gnu.org 2024-05-10 11:16 ` rguenth at gcc dot gnu.org 2024-05-29 0:11 ` pinskia at gcc dot gnu.org 2 siblings, 0 replies; 4+ messages in thread From: pinskia at gcc dot gnu.org @ 2024-05-09 16:40 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115004 --- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> --- Note this works with the IR coming out of the C front-end but NOT the IR coming out from the C++ front-end. Yes the front-ends are different. ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/115004] [11/12/13/14/15 Regression] Missed optimization for Dead Code Elimination 2024-05-09 9:06 [Bug tree-optimization/115004] New: [11/12/13/14/15 Regression] Missed optimization for Dead Code Elimination 652023330028 at smail dot nju.edu.cn 2024-05-09 16:40 ` [Bug tree-optimization/115004] " pinskia at gcc dot gnu.org @ 2024-05-10 11:16 ` rguenth at gcc dot gnu.org 2024-05-29 0:11 ` pinskia at gcc dot gnu.org 2 siblings, 0 replies; 4+ messages in thread From: rguenth at gcc dot gnu.org @ 2024-05-10 11:16 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115004 Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Target Milestone|--- |11.5 Known to work| |8.1.0 ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/115004] [11/12/13/14/15 Regression] Missed optimization for Dead Code Elimination 2024-05-09 9:06 [Bug tree-optimization/115004] New: [11/12/13/14/15 Regression] Missed optimization for Dead Code Elimination 652023330028 at smail dot nju.edu.cn 2024-05-09 16:40 ` [Bug tree-optimization/115004] " pinskia at gcc dot gnu.org 2024-05-10 11:16 ` rguenth at gcc dot gnu.org @ 2024-05-29 0:11 ` pinskia at gcc dot gnu.org 2 siblings, 0 replies; 4+ messages in thread From: pinskia at gcc dot gnu.org @ 2024-05-29 0:11 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115004 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Ever confirmed|0 |1 Last reconfirmed| |2024-05-29 Known to fail| |8.1.0 Known to work|8.1.0 |7.5.0 Status|UNCONFIRMED |NEW --- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> --- Confirmed. Both front-ends regress in GCC 8. But it was fixed in GCC 14 when using the C front-end. ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2024-05-29 0:11 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2024-05-09 9:06 [Bug tree-optimization/115004] New: [11/12/13/14/15 Regression] Missed optimization for Dead Code Elimination 652023330028 at smail dot nju.edu.cn 2024-05-09 16:40 ` [Bug tree-optimization/115004] " pinskia at gcc dot gnu.org 2024-05-10 11:16 ` rguenth at gcc dot gnu.org 2024-05-29 0:11 ` pinskia at gcc dot gnu.org
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