On Sun, Nov 28, 2021 at 3:02 PM Roger Sayle <ro...@nextmovesoftware.com> wrote:
>
>
> This patch builds on the recent improvements to TImode rotations (and
> Jakub's fixes to shldq/shrdq patterns). Now that expanding a TImode
> rotation can never fail, it is safe to allow general_operand constraints
> on the QImode shift amounts in rotlv1ti3 and rotrv1ti3 patterns.
> I've also made an additional tweak to ix86_expand_v1ti_to_ti to use
> vec_extract via V2DImode, which avoid using memory and takes advantage
> vpextrq on recent hardware.
>
> For the following test case:
>
> typedef unsigned __int128 uv1ti __attribute__ ((__vector_size__ (16)));
> uv1ti rotr(uv1ti x, unsigned int i) { return (x >> i) | (x << (128-i)); }
>
> GCC with -O2 -mavx2 would previously generate:
>
> rotr: vmovdqa %xmm0, -24(%rsp)
> movq -16(%rsp), %rdx
> movl %edi, %ecx
> xorl %esi, %esi
> movq -24(%rsp), %rax
> shrdq %rdx, %rax
> shrq %cl, %rdx
> testb $64, %dil
> cmovne %rdx, %rax
> cmovne %rsi, %rdx
> negl %ecx
> xorl %edi, %edi
> andl $127, %ecx
> vmovq %rax, %xmm2
> movq -24(%rsp), %rax
> vpinsrq $1, %rdx, %xmm2, %xmm1
> movq -16(%rsp), %rdx
> shldq %rax, %rdx
> salq %cl, %rax
> testb $64, %cl
> cmovne %rax, %rdx
> cmovne %rdi, %rax
> vmovq %rax, %xmm3
> vpinsrq $1, %rdx, %xmm3, %xmm0
> vpor %xmm1, %xmm0, %xmm0
> ret
>
> with this patch, we now generate:
>
> rotr: movl %edi, %ecx
> vpextrq $1, %xmm0, %rax
> vmovq %xmm0, %rdx
> shrdq %rax, %rdx
> vmovq %xmm0, %rsi
> shrdq %rsi, %rax
> andl $64, %ecx
> movq %rdx, %rsi
> cmovne %rax, %rsi
> cmove %rax, %rdx
> vmovq %rsi, %xmm0
> vpinsrq $1, %rdx, %xmm0, %xmm0
> ret
>
>
> This patch has been tested on x86_64-pc-linux-gnu with make bootstrap
> and make -k check with no new failures. Ok for mainline?
>
>
> 2021-11-28 Roger Sayle <ro...@nextmovesoftware.com>
>
> gcc/ChangeLog
> * config/i386/i386-expand.c (ix86_expand_v1ti_to_ti): Perform the
> conversion via V2DImode using vec_extractv2didi on TARGET_SSE2.
> * config/i386/sse.md (rotlv1ti3, rotrv1ti3): Change constraint
> on QImode shift amounts from const_int_operand to general_operand.
>
> gcc/testsuite/ChangeLog
> * gcc.target/i386/sse2-v1ti-rotate.c: New test case.
OK.
Thanks,
Uros.
>
>
> Thanks in advance,
> Roger
> --
>
