On Tue, Feb 09, 2021 at 12:12:24PM +0100, Jakub Jelinek via Gcc-patches wrote:
> As mentioned in the PR, we don't support arithmetic right V2DImode or
> V4DImode on x86 without -mavx512vl or -mxop. The ISAs indeed don't have
> {,v}psraq instructions until AVX512VL, but we actually can emulate it quite
> easily.
> One case is arithmetic >> 63, we can just emit {,v}pxor; {,v}pcmpgt for
> that for SSE4.2+, or for SSE2 psrad $31; pshufd $0xf5.
> Then arithmetic >> by constant > 32, that can be done with {,v}psrad $31
> and {,v}psrad $(cst-32) and two operand permutation,
> arithmetic >> 32 can be done as {,v}psrad $31 and permutation of that
> and the original operand. Arithmetic >> by constant < 32 can be done
> as {,v}psrad $cst and {,v}psrlq $cst and two operand permutation.
> And arithmetic >> by variable scalar amount can be done as
> arithmetic >> 63, logical >> by the amount, << by (64 - amount of the
> >> 63 result; note that the vector << 64 result in 0) and oring together.
>
> I had to improve the permutation generation so that it actually handles
> the needed permutations (or handles them better).
>
> Richard, does this actually improve the benchmark that regressed?
>
> If not, I guess this is a GCC 12 material.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux.
>
> 2021-02-09 Jakub Jelinek <ja...@redhat.com>
>
> PR tree-optimization/98856
> * config/i386/i386.c (ix86_shift_rotate_cost): Add CODE argument.
> Expect V2DI and V4DI arithmetic right shifts to be emulated.
> (ix86_rtx_costs, ix86_add_stmt_cost): Adjust ix86_shift_rotate_cost
> caller.
> * config/i386/i386-expand.c (expand_vec_perm_2perm_interleave,
> expand_vec_perm_2perm_pblendv): New functions.
> (ix86_expand_vec_perm_const_1): Use them.
> * config/i386/sse.md (ashr<mode>3<mask_name>): Rename to ...
> (<mask_codefor>ashr<mode>3<mask_name>): ... this.
> (ashr<mode>3): New define_expand with VI248_AVX512BW iterator.
> (ashrv4di3): New define_expand.
> (ashrv2di3): Change condition to TARGET_SSE2, handle !TARGET_XOP
> and !TARGET_AVX512VL expansion.
>
> * gcc.target/i386/sse2-psraq-1.c: New test.
> * gcc.target/i386/sse4_2-psraq-1.c: New test.
> * gcc.target/i386/avx-psraq-1.c: New test.
> * gcc.target/i386/avx2-psraq-1.c: New test.
> * gcc.target/i386/avx-pr82370.c: Adjust expected number of vpsrad
> instructions.
> * gcc.target/i386/avx2-pr82370.c: Likewise.
> * gcc.target/i386/avx512f-pr82370.c: Likewise.
> * gcc.target/i386/avx512bw-pr82370.c: Likewise.
> * gcc.dg/torture/vshuf-4.inc: Add two further permutations.
> * gcc.dg/torture/vshuf-8.inc: Likewise.
Ok for trunk now?
https://gcc.gnu.org/pipermail/gcc-patches/2021-February/565026.html
Jakub
