https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87600
Alexandre Oliva <aoliva at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |aoliva at gcc dot gnu.org --- Comment #8 from Alexandre Oliva <aoliva at gcc dot gnu.org> --- I've noticed regressions caused by make_more_copies, in scenarios that used subreg s for the low part of promoted incoming parms. With hard regs, the substitution into a subreg became a reg, but with a pseudo, it remains a subreg, which prevents further combines in some cases, as in e.g. gcc_target/powerpc/20050603-3.c on ppc64. I thought one way to go about it could be to scan for subregs of pseudos copied from hard regs before introducing the additional copies, and introduce the intermediate pseudo with the widest subreg mode if there aren't uses of the full pseudo.