https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104644
--- Comment #6 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Richard Biener <rgue...@gcc.gnu.org>: https://gcc.gnu.org/g:fdc46830f1b793dc791099acfadc3f0f8cc24c0e commit r12-7361-gfdc46830f1b793dc791099acfadc3f0f8cc24c0e Author: Richard Biener <rguent...@suse.de> Date: Wed Feb 23 13:47:01 2022 +0100 middle-end/104644 - recursion with bswap match.pd pattern The following patch avoids infinite recursion during generic folding. The (cmp (bswap @0) INTEGER_CST@1) simplification relies on (bswap @1) actually being simplified, if it is not simplified, we just move the bswap from one operand to the other and if @0 is also INTEGER_CST, we apply the same rule next. The reason why bswap @1 isn't folded to INTEGER_CST is that the INTEGER_CST has TREE_OVERFLOW set on it and fold-const-call.cc predicate punts in such cases: static inline bool integer_cst_p (tree t) { return TREE_CODE (t) == INTEGER_CST && !TREE_OVERFLOW (t); } The patch uses ! modifier to ensure the bswap is simplified and extends support to GENERIC by means of requiring !EXPR_P which is not perfect but a conservative approximation. 2022-02-22 Richard Biener <rguent...@suse.de> PR tree-optimization/104644 * doc/match-and-simplify.texi: Amend ! documentation. * genmatch.cc (expr::gen_transform): Code-generate ! support for GENERIC. (parser::parse_expr): Allow ! for GENERIC. * match.pd (cmp (bswap @0) INTEGER_CST@1): Use ! modifier on bswap. * gcc.dg/pr104644.c: New test. Co-Authored-by: Jakub Jelinek <ja...@redhat.com>
