On Sun, Jul 9, 2023 at 10:35 PM Roger Sayle <ro...@nextmovesoftware.com> wrote:
>
>
> Following Uros' suggestion, this patch adds support for AVX512VL's
> vpro[lr][dq] instructions to the recently added scalar-to-vector (STV)
> enhancements to handle DImode and SImode rotations by a constant.
>
> For the test cases:
>
> unsigned long long rot1(unsigned long long x) {
> return (x>>1) | (x<<63);
> }
>
> void mem1(unsigned long long *p) {
> *p = rot1(*p);
> }
>
> with -m32 -O2 -mavx512vl, we currently generate:
>
> rot1: movl 4(%esp), %eax
> movl 8(%esp), %edx
> movl %eax, %ecx
> shrdl $1, %edx, %eax
> shrdl $1, %ecx, %edx
> ret
>
> mem1: movl 4(%esp), %eax
> vmovq (%eax), %xmm0
> vpshufd $20, %xmm0, %xmm0
> vpsrlq $1, %xmm0, %xmm0
> vpshufd $136, %xmm0, %xmm0
> vmovq %xmm0, (%eax)
> ret
>
> with this patch, we now generate:
>
> rot1: vmovq 4(%esp), %xmm0
> vprorq $1, %xmm0, %xmm0
> vmovd %xmm0, %eax
> vpextrd $1, %xmm0, %edx
> ret
>
> mem1: movl 4(%esp), %eax
> vmovq (%eax), %xmm0
> vprorq $1, %xmm0, %xmm0
> vmovq %xmm0, (%eax)
> ret
>
>
> This patch has been tested on x86_64-pc-linux-gnu (cascadelake which has
> avx512) with make bootstrap and make -k check, both with and without
> --target_board=unix{-m32} with no new failures. Ok for mainline?
>
>
> 2023-07-09 Roger Sayle <ro...@nextmovesoftware.com>
>
> gcc/ChangeLog
> * config/i386/i386-features.cc (compute_convert_gain): Tweak
> gains/costs for ROTATE/ROTATERT by integer constant on AVX512VL.
> (general_scalar_chain::convert_rotate): On TARGET_AVX512F generate
> avx512vl_rolv2di or avx412vl_rolv4si when appropriate.
>
> gcc/testsuite/ChangeLog
> * gcc.target/i386/avx512vl-stv-rotatedi-1.c: New test case.
OK.
Thanks,
Uros.
>
>
> Cheers,
> Roger
> --
>
