https://gcc.gnu.org/g:867f777cee9f44027a3724fbad266c5cfb3a311f
commit r16-4218-g867f777cee9f44027a3724fbad266c5cfb3a311f Author: Jakub Jelinek <[email protected]> Date: Sat Oct 4 17:06:16 2025 +0200 widening_mul: Reset flow sensitive info in maybe_optimize_guarding_check [PR122104] In PR95852 I've added an optimization where next to just pattern recognizing r = x * y; r / x != y or r = x * y; r / x == y as .MUL_OVERFLOW or negation thereof it also recognizes r = x * y; x && (r / x != y) or r = x * y; !x || (r / x == y) by optimizing the guarding condition to always true/false. The problem with that is that some value ranges recorded for the SSA_NAMEs in the formerly conditional, now unconditional basic block can be invalid. This patch fixes it by calling reset_flow_sensitive_info_in_bb if we optimize the guarding condition. 2025-10-04 Jakub Jelinek <[email protected]> PR tree-optimization/122104 * tree-ssa-math-opts.cc (maybe_optimize_guarding_check): Call reset_flow_sensitive_info_in_bb on bb when optimizing out the guarding condition. * gcc.target/i386/pr122104.c: New test. Diff: --- gcc/testsuite/gcc.target/i386/pr122104.c | 12 ++++++++++++ gcc/tree-ssa-math-opts.cc | 1 + 2 files changed, 13 insertions(+) diff --git a/gcc/testsuite/gcc.target/i386/pr122104.c b/gcc/testsuite/gcc.target/i386/pr122104.c new file mode 100644 index 000000000000..be88933e3ec6 --- /dev/null +++ b/gcc/testsuite/gcc.target/i386/pr122104.c @@ -0,0 +1,12 @@ +/* PR tree-optimization/122104 */ +/* { dg-do compile } */ +/* { dg-options "-O2 -fdump-tree-widening_mul-alias" } */ +/* { dg-final { scan-tree-dump "\\.MUL_OVERFLOW" "widening_mul" } } */ +/* { dg-final { scan-tree-dump-not "# RANGE \\\[irange\\\] unsigned int \\\[1, " "widening_mul" } } */ + +int +foo (int x) +{ + int r = (unsigned) x * 35; + return x && ((unsigned) r / x) != 35U; +} diff --git a/gcc/tree-ssa-math-opts.cc b/gcc/tree-ssa-math-opts.cc index a9903b691a49..0db39f330ead 100644 --- a/gcc/tree-ssa-math-opts.cc +++ b/gcc/tree-ssa-math-opts.cc @@ -3834,6 +3834,7 @@ maybe_optimize_guarding_check (vec<gimple *> &mul_stmts, gimple *cond_stmt, else gimple_cond_make_false (zero_cond); update_stmt (zero_cond); + reset_flow_sensitive_info_in_bb (bb); *cfg_changed = true; }
