https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96674
--- Comment #10 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:49e8c14ef6f1f968602a04c8499a672182590e87 commit r11-6817-g49e8c14ef6f1f968602a04c8499a672182590e87 Author: Eugene Rozenfeld <ero...@microsoft.com> Date: Wed Dec 9 16:44:25 2020 -0800 Optimize combination of comparisons to dec+compare This patch adds patterns for optimizing x < y || y == XXX_MIN to x <= y-1 x >= y && y != XXX_MIN to x > y-1 if y is an integer with TYPE_OVERFLOW_WRAPS. This fixes pr96674. Tested on x86_64-pc-linux-gnu. For this function bool f(unsigned a, unsigned b) { return (b == 0) | (a < b); } the code without the patch is test esi,esi sete al cmp esi,edi seta dl or eax,edx ret the code with the patch is sub esi,0x1 cmp esi,edi setae al ret PR tree-optimization/96674 gcc/ * match.pd: New patterns: x < y || y == XXX_MIN --> x <= y - 1 x >= y && y != XXX_MIN --> x > y - 1 gcc/testsuite * gcc.dg/pr96674.c: New tests.
