https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103773
--- Comment #5 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Roger Sayle <sa...@gcc.gnu.org>: https://gcc.gnu.org/g:ef26c151c14a87177d46fd3d725e7f82e040e89f commit r12-6106-gef26c151c14a87177d46fd3d725e7f82e040e89f Author: Roger Sayle <ro...@nextmovesoftware.com> Date: Thu Dec 23 12:33:07 2021 +0000 x86: PR target/103773: Fix wrong-code with -Oz from pop to memory. This is a fix to PR target/103773 where -Oz shouldn't use push/pop on x86 to shrink writing small integer constants to memory. Instead clang uses "andl $0, mem" for writing zero, and "orl $-1, mem" when writing -1 to memory when using -Oz. This patch implements this via peephole2 where we can confirm that its ok to clobber the flags. 2021-12-23 Roger Sayle <ro...@nextmovesoftware.com> Uroš Bizjak <ubiz...@gmail.com> gcc/ChangeLog PR target/103773 * config/i386/i386.md (*mov<mode>_and): New define_insn for writing a zero to memory using AND. (*mov<mode>_or): Extend to allow memory destination and HImode. (*movdi_internal): Remove -Oz push/pop optimization from here. (*movsi_internal): Likewise. (peephole2): Perform -Oz push/pop optimization here, only for register destinations, values other than zero, and in functions that don't used the red zone. (peephole2): With -Oz, convert writes of 0 or -1 to memory into their clobber forms, i.e. *mov<mode>_and and *mov<mode>_or resp. gcc/testsuite/ChangeLog PR target/103773 * gcc.target/i386/pr103773-2.c: New test case. * gcc.target/i386/pr103773.c: New test case.
