https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102705
--- Comment #12 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The trunk branch has been updated by Andrew Pinski <pins...@gcc.gnu.org>: https://gcc.gnu.org/g:903ab914dd48c3131ded0cf427da50c23168024c commit r15-6929-g903ab914dd48c3131ded0cf427da50c23168024c Author: Andrew Pinski <quic_apin...@quicinc.com> Date: Tue Jan 14 19:38:47 2025 -0800 match: Simplify `1 >> x` into `x == 0` [PR102705] This in this PR we have missed optimization where we miss that, `1 >> x` and `(1 >> x) ^ 1` can't be equal. There are a few ways of optimizing this, the easiest and simpliest is to simplify `1 >> x` into just `x == 0` as those are equivalant (if we ignore out of range values for x). we already have an optimization for `(1 >> X) !=/== 0` so the only difference here is we don't need the `!=/== 0` part to do the transformation. So this removes the `(1 >> X) !=/== 0` transformation and just adds a simplfied `1 >> x` -> `x == 0` one. Bootstrapped and tested on x86_64-linux-gnu. PR tree-optimization/102705 gcc/ChangeLog: * match.pd (`(1 >> X) != 0`): Remove pattern. (`1 >> x`): New pattern. gcc/testsuite/ChangeLog: * gcc.dg/tree-ssa/pr105832-2.c: Update testcase. * gcc.dg/tree-ssa/pr96669-1.c: Likewise. * gcc.dg/tree-ssa/pr102705-1.c: New test. * gcc.dg/tree-ssa/pr102705-2.c: New test. Signed-off-by: Andrew Pinski <quic_apin...@quicinc.com>
