https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98629
--- Comment #4 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:24ea113f75cfad38894dc1ad16b23c0538ef17d4 commit r11-6610-g24ea113f75cfad38894dc1ad16b23c0538ef17d4 Author: Jakub Jelinek <ja...@redhat.com> Date: Tue Jan 12 11:04:46 2021 +0100 widening_mul: Fix up ICE caused by my signed multiplication overflow pattern recognition changes [PR98629] As the testcase shows, my latest changes caused ICE on that testcase. The problem is that arith_overflow_check_p now can change the use_stmt argument (has a reference), so that if it succeeds (returns non-zero), it points it to the GIMPLE_COND or EQ/NE or COND_EXPR assignment from the TRUNC_DIV_EXPR assignment. The problem was that it would change use_stmt also if it returned 0 in some cases, such as multiple imm uses of the division, and in one of the callers if arith_overflow_check_p returns 0 it looks at use_stmt again and performs other checks, which of course assumes that use_stmt is the one passed to arith_overflow_check_p and not e.g. NULL instead or some other unrelated stmt. The following patch fixes that by only changing use_stmt when we are about to return non-zero (for the MULT_EXPR case, which is the only one with the need to use different use_stmt). 2021-01-12 Jakub Jelinek <ja...@redhat.com> PR tree-optimization/98629 * tree-ssa-math-opts.c (arith_overflow_check_p): Don't update use_stmt unless returning non-zero. * gcc.c-torture/compile/pr98629.c: New test.
