On Tue, Apr 29, 2025 at 11:40 PM H.J. Lu <hjl.to...@gmail.com> wrote: > > SMALL_REGISTER_CLASSES was added by > > commit c98f874233428d7e6ba83def7842fd703ac0ddf1 > Author: James Van Artsdalen <j...@gnu.org> > Date: Sun Feb 9 13:28:48 1992 +0000 > > Initial revision > > which became TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P. It is false from > day 1 for i386. Since x86-64 doubles the number of registers, Change > TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P to return false for x86-64 > and update decrease_live_ranges_number to skip hard register if > targetm.class_likely_spilled_p returns true. These extend the live > range of rbp, r8-r31 and xmm1-xmm31 registers. > > PR target/118996 > * ira.cc (decrease_live_ranges_number): Skip hard register if > targetm.class_likely_spilled_p returns true. > * config/i386/i386.cc (ix86_small_register_classes_for_mode_p): > New. > (TARGET_SMALL_REGISTER_CLASSES_FOR_MODE_P): Use it.
Redeclaring X86_64 is too risky. We can perhaps enable integer registers for APX because it is a relatively new development. I'm undecided about AVX-512, perhaps this is worth a try. In the case of AVX-512, can you provide some performance numbers to assess the risk/benefit ratio? Uros.
