On Mon, May 31, 2021 at 11:07 AM Jeff Law <jeffreya...@gmail.com> wrote: > > > > On 5/31/2021 6:04 AM, H.J. Lu wrote: > > On Sun, May 30, 2021 at 11:49 AM Jeff Law <jeffreya...@gmail.com> wrote: > >> > >> > >> On 5/11/2021 5:35 PM, H.J. Lu via Gcc-patches wrote: > >>> Add TARGET_READ_MEMSET_VALUE and TARGET_GEN_MEMSET_VALUE to support > >>> target instructions to duplicate QImode value to TImode/OImode/XImode > >>> value for memmset. Define SCRATCH_SSE_REG as a scratch register for > >>> ix86_gen_memset_value. > >>> > >>> gcc/ > >>> > >>> PR middle-end/90773 > >>> * builtins.c (builtin_memset_read_str): Call > >>> targetm.read_memset_value. > >>> (builtin_memset_gen_str): Call targetm.gen_memset_value. > >>> * target.def (read_memset_value): New hook. > >>> (gen_memset_value): Likewise. > >>> * targhooks.c: Inclue "builtins.h". > >>> (default_read_memset_value): New function. > >>> (default_gen_memset_value): Likewise. > >>> * targhooks.h (default_read_memset_value): New prototype. > >>> (default_gen_memset_value): Likewise. > >>> * config/i386/i386-expand.c (ix86_expand_vector_init_duplicate): > >>> Make it global. > >>> * config/i386/i386-protos.h (ix86_minimum_incoming_stack_boundary): > >>> New. > >>> (ix86_expand_vector_init_duplicate): Likewise. > >>> * config/i386/i386.c (ix86_minimum_incoming_stack_boundary): Add > >>> an argument to ignore stack_alignment_estimated. It is passed > >>> as false by default. > >>> (ix86_gen_memset_value_from_prev): New function. > >>> (ix86_gen_memset_value): Likewise. > >>> (ix86_read_memset_value): Likewise. > >>> (TARGET_GEN_MEMSET_VALUE): New. > >>> (TARGET_READ_MEMSET_VALUE): Likewise. > >>> * config/i386/i386.h (SCRATCH_SSE_REG): New. > >>> * doc/tm.texi.in: Add TARGET_READ_MEMSET_VALUE and > >>> TARGET_GEN_MEMSET_VALUE hooks. > >>> * doc/tm.texi: Regenerated. > >>> > >>> gcc/testsuite/ > >>> > >>> PR middle-end/90773 > >>> * gcc.target/i386/pr90773-15.c: New test. > >>> * gcc.target/i386/pr90773-16.c: Likewise. > >>> * gcc.target/i386/pr90773-17.c: Likewise. > >>> * gcc.target/i386/pr90773-18.c: Likewise. > >>> * gcc.target/i386/pr90773-19.c: Likewise. > >> Why does this need target hooks? ISTM the right way to go here is to > >> just emit the constant load to the target register and let the target > >> figure out how best to construct the constant into the register. If > >> that means load it via QImode and broadcast, that's fine, but I'm not > >> sure why that's not all implemented in the target files. > >> > > I will submit a patch to add optabs instead. > I may be missing something, but I'm not even sure why we need special > optabs. > > Aren't you just trying to efficiently get a constant element broadcast > across an entire vector?
Since vec_duplicate must not fail and for broadcast from a constant QImode value, vec_duplicate may not be faster than a compile-time constant, I am adding vec_const_duplicate. If vec_duplicate can fail, I don't need vec_const_duplicate. -- H.J.
