https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98335
--- Comment #9 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:251ea6dfbdb4448875e41081682bb3aa451b5729 commit r12-7616-g251ea6dfbdb4448875e41081682bb3aa451b5729 Author: Roger Sayle <ro...@nextmovesoftware.com> Date: Fri Mar 11 17:57:12 2022 +0000 PR tree-optimization/98335: New peephole2 xorl;movb -> movzbl This patch is the backend piece of my proposed fix to PR tree-opt/98335, to allow C++ partial struct initialization to be as efficient/optimized as full struct initialization. With the middle-end patch just posted to gcc-patches, the test case in the PR compiles on x86_64-pc-linux-gnu with -O2 to: xorl %eax, %eax movb c(%rip), %al ret with this additional peephole2 (actually four peephole2s): movzbl c(%rip), %eax ret 2022-03-11 Roger Sayle <ro...@nextmovesoftware.com> gcc/ChangeLog PR tree-optimization/98335 * config/i386/i386.md (peephole2): Eliminate redundant insv. Combine movl followed by movb. Transform xorl followed by a suitable movb or movw into the equivalent movz[bw]l. gcc/testsuite/ChangeLog PR tree-optimization/98335 * g++.target/i386/pr98335.C: New test case. * gcc.target/i386/pr98335.c: New test case.
