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* [Bug tree-optimization/101508] New: Possible undefined behaviour in cpp program using "unsigned" type starting from GCC 9 @ 2021-07-19 10:25 pnarsing at mathworks dot com 2021-07-19 10:46 ` [Bug tree-optimization/101508] [9/10/11/12 Regression] Possible undefined behaviour in cpp program using "unsigned" type starting with r9-4145 jakub at gcc dot gnu.org ` (6 more replies) 0 siblings, 7 replies; 8+ messages in thread From: pnarsing at mathworks dot com @ 2021-07-19 10:25 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101508 Bug ID: 101508 Summary: Possible undefined behaviour in cpp program using "unsigned" type starting from GCC 9 Product: gcc Version: 10.3.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: pnarsing at mathworks dot com Target Milestone: --- Hi Team, I'm observing an optimization issue while compiling with GCC 10.3 . On investigating figured that issue is reproducible in GCC 9 as well . This can be reproduced by simple test code mentioned below : ------------------------------------------------------ using int_type = unsigned int; // works without "unsigned" int_type constexpr start{0}; // works if >= 1 int_type constexpr stop{3}; // works if <= 2 int_type constexpr mult{2}; // works if != 2 int main() { int result = 0; for(int_type aa = start; aa < stop; ++aa) { int_type const bb = aa * mult; // works if volatile if (aa > bb) { return 99; } ++result; } return result; // should be == stop } ---------------------------------------------------------------- This code snippet returns 99 instead of 3 . You can check the following link to see the issue reproducibility: https://godbolt.org/z/zd79PPKfn Modifying compiler option to -O1 and -Og avoids the issue. ^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug tree-optimization/101508] [9/10/11/12 Regression] Possible undefined behaviour in cpp program using "unsigned" type starting with r9-4145 2021-07-19 10:25 [Bug tree-optimization/101508] New: Possible undefined behaviour in cpp program using "unsigned" type starting from GCC 9 pnarsing at mathworks dot com @ 2021-07-19 10:46 ` jakub at gcc dot gnu.org 2021-07-19 11:00 ` rguenth at gcc dot gnu.org ` (5 subsequent siblings) 6 siblings, 0 replies; 8+ messages in thread From: jakub at gcc dot gnu.org @ 2021-07-19 10:46 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101508 Jakub Jelinek <jakub at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |amker at gcc dot gnu.org Status|UNCONFIRMED |NEW Last reconfirmed| |2021-07-19 Summary|Possible undefined |[9/10/11/12 Regression] |behaviour in cpp program |Possible undefined |using "unsigned" type |behaviour in cpp program |starting from GCC 9 |using "unsigned" type | |starting with r9-4145 Target Milestone|--- |9.5 Ever confirmed|0 |1 --- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> --- Started with r9-4145-ga81e2c6240655f60a49c16e0d8bbfd2ba40bba51 Simplified C testcase: int main () { unsigned i; for (i = 0; i < 3; ++i) { if (i > i * 2) __builtin_abort (); } return 0; } ^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug tree-optimization/101508] [9/10/11/12 Regression] Possible undefined behaviour in cpp program using "unsigned" type starting with r9-4145 2021-07-19 10:25 [Bug tree-optimization/101508] New: Possible undefined behaviour in cpp program using "unsigned" type starting from GCC 9 pnarsing at mathworks dot com 2021-07-19 10:46 ` [Bug tree-optimization/101508] [9/10/11/12 Regression] Possible undefined behaviour in cpp program using "unsigned" type starting with r9-4145 jakub at gcc dot gnu.org @ 2021-07-19 11:00 ` rguenth at gcc dot gnu.org 2022-01-17 14:02 ` rguenth at gcc dot gnu.org ` (4 subsequent siblings) 6 siblings, 0 replies; 8+ messages in thread From: rguenth at gcc dot gnu.org @ 2021-07-19 11:00 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101508 Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Depends on| |100740 Keywords| |wrong-code --- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> --- This one is resolved with the (bogus) fix for PR100740 Referenced Bugs: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100740 [Bug 100740] [9/10/11/12 Regression] wrong code at -O1 and above on x86_64-linux-gnu since r9-4145 ^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug tree-optimization/101508] [9/10/11/12 Regression] Possible undefined behaviour in cpp program using "unsigned" type starting with r9-4145 2021-07-19 10:25 [Bug tree-optimization/101508] New: Possible undefined behaviour in cpp program using "unsigned" type starting from GCC 9 pnarsing at mathworks dot com 2021-07-19 10:46 ` [Bug tree-optimization/101508] [9/10/11/12 Regression] Possible undefined behaviour in cpp program using "unsigned" type starting with r9-4145 jakub at gcc dot gnu.org 2021-07-19 11:00 ` rguenth at gcc dot gnu.org @ 2022-01-17 14:02 ` rguenth at gcc dot gnu.org 2022-01-24 12:15 ` cvs-commit at gcc dot gnu.org ` (3 subsequent siblings) 6 siblings, 0 replies; 8+ messages in thread From: rguenth at gcc dot gnu.org @ 2022-01-17 14:02 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101508 Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Priority|P3 |P2 ^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug tree-optimization/101508] [9/10/11/12 Regression] Possible undefined behaviour in cpp program using "unsigned" type starting with r9-4145 2021-07-19 10:25 [Bug tree-optimization/101508] New: Possible undefined behaviour in cpp program using "unsigned" type starting from GCC 9 pnarsing at mathworks dot com ` (2 preceding siblings ...) 2022-01-17 14:02 ` rguenth at gcc dot gnu.org @ 2022-01-24 12:15 ` cvs-commit at gcc dot gnu.org 2022-01-24 12:44 ` [Bug tree-optimization/101508] [9/10/11 " rguenth at gcc dot gnu.org ` (2 subsequent siblings) 6 siblings, 0 replies; 8+ messages in thread From: cvs-commit at gcc dot gnu.org @ 2022-01-24 12:15 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101508 --- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Richard Biener <rguenth@gcc.gnu.org>: https://gcc.gnu.org/g:f1af8528d34418bc874ae9d993ee0dc3559972d2 commit r12-6844-gf1af8528d34418bc874ae9d993ee0dc3559972d2 Author: Richard Biener <rguenther@suse.de> Date: Mon Jan 24 11:50:06 2022 +0100 tree-optimization/102131 - fix niter analysis wrt overflow This fixes the overflow issues seen with analyzing BASE0 + STEP0 cmp BASE1 + STEP1 as BASE0 + STEP0 - STEP1 cmp BASE1 by following the logic we have when simplifying comparisons. 2022-01-24 Richard Biener <rguenther@suse.de> Jiufu Guo <guojiufu@linux.ibm.com> PR tree-optimization/100740 PR tree-optimization/101508 PR tree-optimization/101972 PR tree-optimization/102131 * tree-ssa-loop-niter.cc (number_of_iterations_cond): Properly constrain BASE0 + STEP0 cmp BASE1 + STEP1 to BASE0 + STEP0 - STEP1 cmp BASE1 transform. * gcc.dg/torture/pr100740.c: New testcase. * gcc.dg/torture/pr101508.c: Likewise. * gcc.dg/torture/pr101972.c: Likewise. * gcc.dg/torture/pr102131-1.c: Likewise. * gcc.dg/torture/pr102131-2.c: Likewise. * gcc.dg/torture/pr102131-3.c: Likewise. * gcc.dg/torture/pr102131-4.c: Likewise. ^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug tree-optimization/101508] [9/10/11 Regression] Possible undefined behaviour in cpp program using "unsigned" type starting with r9-4145 2021-07-19 10:25 [Bug tree-optimization/101508] New: Possible undefined behaviour in cpp program using "unsigned" type starting from GCC 9 pnarsing at mathworks dot com ` (3 preceding siblings ...) 2022-01-24 12:15 ` cvs-commit at gcc dot gnu.org @ 2022-01-24 12:44 ` rguenth at gcc dot gnu.org 2022-01-24 12:46 ` rguenth at gcc dot gnu.org 2024-07-19 7:15 ` rguenth at gcc dot gnu.org 6 siblings, 0 replies; 8+ messages in thread From: rguenth at gcc dot gnu.org @ 2022-01-24 12:44 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101508 Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Summary|[9/10/11/12 Regression] |[9/10/11 Regression] |Possible undefined |Possible undefined |behaviour in cpp program |behaviour in cpp program |using "unsigned" type |using "unsigned" type |starting with r9-4145 |starting with r9-4145 Status|NEW |ASSIGNED Known to work| |12.0 Assignee|unassigned at gcc dot gnu.org |rguenth at gcc dot gnu.org ^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug tree-optimization/101508] [9/10/11 Regression] Possible undefined behaviour in cpp program using "unsigned" type starting with r9-4145 2021-07-19 10:25 [Bug tree-optimization/101508] New: Possible undefined behaviour in cpp program using "unsigned" type starting from GCC 9 pnarsing at mathworks dot com ` (4 preceding siblings ...) 2022-01-24 12:44 ` [Bug tree-optimization/101508] [9/10/11 " rguenth at gcc dot gnu.org @ 2022-01-24 12:46 ` rguenth at gcc dot gnu.org 2024-07-19 7:15 ` rguenth at gcc dot gnu.org 6 siblings, 0 replies; 8+ messages in thread From: rguenth at gcc dot gnu.org @ 2022-01-24 12:46 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101508 Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Resolution|--- |DUPLICATE Status|ASSIGNED |RESOLVED --- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> --- Dup. *** This bug has been marked as a duplicate of bug 100740 *** ^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug tree-optimization/101508] [9/10/11 Regression] Possible undefined behaviour in cpp program using "unsigned" type starting with r9-4145 2021-07-19 10:25 [Bug tree-optimization/101508] New: Possible undefined behaviour in cpp program using "unsigned" type starting from GCC 9 pnarsing at mathworks dot com ` (5 preceding siblings ...) 2022-01-24 12:46 ` rguenth at gcc dot gnu.org @ 2024-07-19 7:15 ` rguenth at gcc dot gnu.org 6 siblings, 0 replies; 8+ messages in thread From: rguenth at gcc dot gnu.org @ 2024-07-19 7:15 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101508 Bug 101508 depends on bug 100740, which changed state. Bug 100740 Summary: [11 Regression] wrong code at -O1 and above on x86_64-linux-gnu since r9-4145-ga81e2c6240655f60 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100740 What |Removed |Added ---------------------------------------------------------------------------- Status|ASSIGNED |RESOLVED Resolution|--- |FIXED ^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2024-07-19 7:15 UTC | newest] Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2021-07-19 10:25 [Bug tree-optimization/101508] New: Possible undefined behaviour in cpp program using "unsigned" type starting from GCC 9 pnarsing at mathworks dot com 2021-07-19 10:46 ` [Bug tree-optimization/101508] [9/10/11/12 Regression] Possible undefined behaviour in cpp program using "unsigned" type starting with r9-4145 jakub at gcc dot gnu.org 2021-07-19 11:00 ` rguenth at gcc dot gnu.org 2022-01-17 14:02 ` rguenth at gcc dot gnu.org 2022-01-24 12:15 ` cvs-commit at gcc dot gnu.org 2022-01-24 12:44 ` [Bug tree-optimization/101508] [9/10/11 " rguenth at gcc dot gnu.org 2022-01-24 12:46 ` rguenth at gcc dot gnu.org 2024-07-19 7:15 ` rguenth at gcc dot gnu.org
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