https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119183
--- Comment #8 from GCC 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:20e5aa9cc1519f871cce25dbfdc149d9d60da779 commit r15-7947-g20e5aa9cc1519f871cce25dbfdc149d9d60da779 Author: Jakub Jelinek <ja...@redhat.com> Date: Tue Mar 11 11:01:55 2025 +0100 tree: Improve skip_simple_arithmetic [PR119183] The following testcase takes very long time to compile, because skip_simple_arithmetic decides to first call tree_invariant_p on the second argument (and indirectly recurse there). I think before canonicalization of operands for commutative binary expressions (and for non-commutative ones always) it is pretty common that the first operand is a constant, something which tree_invariant_p handles immediately, so the following patch special cases that; I've added there a tree_invariant_p call too after the checks, while it is not really needed currently, tree_invariant_p has the same checks, I wanted to be prepared in case tree_invariant_p changes. But if you think I should avoid it, I can drop it too. This is just a partial fix, I think one can certainly construct a testcase which will still have horrible compile time complexity (but I've tried and haven't managed to do so), so perhaps we should just limit the recursion depth through skip_simple_arithmetic/tree_invariant_p with some defaulted argument. 2025-03-11 Jakub Jelinek <ja...@redhat.com> PR c/119183 * tree.cc (skip_simple_arithmetic): If first operand of binary expr is TREE_CONSTANT or TREE_READONLY with no side-effects, call tree_invariant_p on that operand first instead of on the second. * gcc.dg/pr119183.c: New test.
