https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94857
--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jakub Jelinek <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:a229f9b3737062c6e853879be6683f3f3e4a6661 commit r11-197-ga229f9b3737062c6e853879be6683f3f3e4a6661 Author: Jakub Jelinek <ja...@redhat.com> Date: Fri May 8 10:03:56 2020 +0200 ix86: Add peephole2 for *add<mode>3_cc_overflow_1 followed by matching memory store [PR94857] The following peephole2 changes: - addl (%rdi), %esi + xorl %eax, %eax + addl %esi, (%rdi) setc %al - movl %esi, (%rdi) - movzbl %al, %eax ret on the testcase. *add<mode>3_cc_overflow_1, being an add{l,q} insn, is commutative, so if TARGET_READ_MODIFY_WRITE we can replace addl (%rdi), %esi; movl %esi, (%rdi) with addl %esi, (%rdi) if %esi is dead after those two insns. 2020-05-08 Jakub Jelinek <ja...@redhat.com> PR target/94857 * config/i386/i386.md (peephole2 after *add<mode>3_cc_overflow_1): New define_peephole2. * gcc.target/i386/pr94857.c: New test.
