https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55157
--- Comment #13 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Aldy Hernandez <al...@gcc.gnu.org>: https://gcc.gnu.org/g:a239a63f868e29e9276088e7c0fb00804c2903ba commit r13-3761-ga239a63f868e29e9276088e7c0fb00804c2903ba Author: Aldy Hernandez <al...@redhat.com> Date: Fri Nov 4 22:24:42 2022 +0100 Improve multiplication by powers of 2 in range-ops. For unsigned numbers, multiplication by X, where X is a power of 2 is [0,0][X,+INF]. This patch causes a regression to g++.dg/pr71488.C where -Wstringop-overflow gets the same IL as before, but better ranges cause it to issue a bogus warning. I will create a PR with some notes. No discernible changes in performance. Tested on x86-64 Linux. PR tree-optimization/55157 gcc/ChangeLog: * range-op.cc (operator_mult::wi_fold): Optimize multiplications by powers of 2. gcc/testsuite/ChangeLog: * gcc.dg/tree-ssa/pr55157.c: New test.
