https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95903
--- Comment #10 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jakub Jelinek <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:37995960984ea2222346dd9d168d332cd6f7adf0 commit r11-1685-g37995960984ea2222346dd9d168d332cd6f7adf0 Author: Jakub Jelinek <ja...@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 <ja...@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.
