https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114760
--- Comment #2 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Di Zhao <dz...@gcc.gnu.org>: https://gcc.gnu.org/g:1b0919cd147a2b6ccdee2b1217bf0200bdcc87aa commit r15-380-g1b0919cd147a2b6ccdee2b1217bf0200bdcc87aa Author: dzhao.ampere <di.z...@amperecomputing.com> Date: Fri May 10 11:55:18 2024 +0800 tree-optimization/114760 - check variants of >> and << in loop-niter When recognizing bit counting idiom, include pattern "x * 2" for "x << 1", and "x / 2" for "x >> 1" (given x is unsigned). gcc/ChangeLog: PR tree-optimization/114760 * tree-ssa-loop-niter.cc (is_lshift_by_1): New function to check if STMT is equivalent to x << 1. (is_rshift_by_1): New function to check if STMT is equivalent to x >> 1. (number_of_iterations_cltz): Enhance the identification of logical shift by one. (number_of_iterations_cltz_complement): Enhance the identification of logical shift by one. gcc/testsuite/ChangeLog: PR tree-optimization/114760 * gcc.dg/tree-ssa/pr114760-1.c: New test. * gcc.dg/tree-ssa/pr114760-2.c: New test.