https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119285
--- Comment #3 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Vladimir Makarov <vmaka...@gcc.gnu.org>: https://gcc.gnu.org/g:8e0e17677afc1a93aa31b8b83849848b7bb52b9b commit r15-8237-g8e0e17677afc1a93aa31b8b83849848b7bb52b9b Author: Vladimir N. Makarov <vmaka...@redhat.com> Date: Mon Mar 17 15:21:46 2025 -0400 [PR119285][IRA]: Use an additional way of reg equiv invariant substitution correctness Patch for PR114991 resulted in 5% decrease of SPEC2017 lbm performance on Zen2 and Zen4. For one RTL insn of lbm, LRA with PR114991 patch can not confirm that the equivalence insertion will create a valid RTL insn. This resulted in that the pseudo equiv was assumed costly and pseudo was assigned to hard reg (caller saved as the pseudo lives through calls) and some other pseudos did not get hard regs as it was before PR114991 patch. The insn in question is `pseudo1 = pseduo2 + pseudo3` where pseudo2 has equiv `hard_reg + const`. The old code recognized the insn after equiv substitution as LEA. The new code failed. The patch here makes to use two ways for equiv subsbtitution correctness, the old one and new one (mostly for memory addresses where the old code fails to find the substitution correctness). So given patch fixes lbm performance degradation and actually makes GCC to generate the same code as it was before PR114991 patch. gcc/ChangeLog: PR rtl-optimization/119285 * ira-costs.cc (equiv_can_be_consumed_p): Use 2 ways for recognizing a valid insn after equiv insertion.
