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From: "cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug middle-end/95903] gcc 10: wrong code with -fwrapv Date: Wed, 16 Sep 2020 19:22:27 +0000 [thread overview] Message-ID: <bug-95903-4-vQ73eii0cp@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-95903-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95903 --- Comment #12 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-9 branch has been updated by Jakub Jelinek <jakub@gcc.gnu.org>: https://gcc.gnu.org/g:a1eb6e41832816b671d3b945014f7e8255167470 commit r9-8902-ga1eb6e41832816b671d3b945014f7e8255167470 Author: Jakub Jelinek <jakub@redhat.com> Date: Sat Jun 27 12:38:23 2020 +0200 c-family: Use TYPE_OVERFLOW_UNDEFINED instead of !TYPE_UNSIGNED in pointer_sum [PR95903] For lp64 targets and int off ... ptr[off + 1] is lowered in pointer_sum to *(ptr + ((sizetype) off + (sizetype) 1)). That is fine when signed integer wrapping is undefined (and is not done already if off has unsigned type), but changes behavior for -fwrapv, where overflow is well defined. Runtime test could be: int main () { char *p = __builtin_malloc (0x100000000UL); if (!p) return 0; char *q = p + 0x80000000UL; int o = __INT_MAX__; q[o + 1] = 1; if (q[-__INT_MAX__ - 1] != 1) __builtin_abort (); return 0; } with -fwrapv or so, not included in the testsuite because it requires 4GB allocation (with some other test it would be enough to have something slightly above 2GB, but still...). 2020-06-27 Jakub Jelinek <jakub@redhat.com> PR middle-end/95903 gcc/c-family/ * c-common.c (pointer_int_sum): Use TYPE_OVERFLOW_UNDEFINED instead of !TYPE_UNSIGNED check to see if we can apply distributive law and handle smaller precision intop operands separately. gcc/testsuite/ * c-c++-common/pr95903.c: New test. (cherry picked from commit 37995960984ea2222346dd9d168d332cd6f7adf0)
next prev parent reply other threads:[~2020-09-16 19:22 UTC|newest] Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-06-25 23:25 [Bug middle-end/95903] New: " markus at oberhumer dot com 2020-06-26 6:30 ` [Bug middle-end/95903] " jakub at gcc dot gnu.org 2020-06-26 7:41 ` markus at oberhumer dot com 2020-06-26 8:05 ` jakub at gcc dot gnu.org 2020-06-26 8:35 ` markus at oberhumer dot com 2020-06-26 8:56 ` jakub at gcc dot gnu.org 2020-06-26 10:38 ` markus at oberhumer dot com 2020-06-26 11:03 ` jakub at gcc dot gnu.org 2020-06-26 11:17 ` markus at oberhumer dot com 2020-06-26 11:36 ` markus at oberhumer dot com 2020-06-27 10:42 ` cvs-commit at gcc dot gnu.org 2020-06-29 9:35 ` cvs-commit at gcc dot gnu.org 2020-09-16 19:22 ` cvs-commit at gcc dot gnu.org [this message] 2020-09-17 17:55 ` jakub at gcc dot gnu.org
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