On Mon, Jul 27, 2015 at 03:38:55PM +0100, Wilco Dijkstra wrote:
> This is basically the same as the shl version but for the shr patterns.
>
> Various instructions are supported as integer operations as well as SIMD on
> AArch64. When
> register pressure is high, lra-constraints inserts spill code without taking
> the allocation
> class into account, and basically chooses the first available pattern that
> matches. Since this
> instruction has the SIMD version first it is usually chosen eventhough some
> of the operands
> are eventually allocated to integer registers. The result is inefficient code
> not only due to
> the higher latency of SIMD instructions but also due to the extra int<->FP
> moves. Placing the
> integer variant first in the shr pattern generates far more optimal spill
> code.
>
> 2015-07-27 Wilco Dijkstra
>
> * gcc/config/aarch64/aarch64.md (aarch64_lshr_sisd_or_int_3):
> Place integer variant first. (aarch64_ashr_sisd_or_int_3):
> Likewise.
This ChangeLog looks odd to me. It should include details of the
new alternative added to aarch64_lshr_sis_or_int_3, and also
be formatted as so:
* gcc/config/aarch64/aarch64.md (aarch64_lshr_sisd_or_int_3):
Place integer variant first.
(aarch64_ashr_sisd_or_int_3): Likewise.
Otherwise, this patch looks OK to me, so I've applied it on your behalf
as revision 226253.
Thanks,
James
> ---
> gcc/config/aarch64/aarch64.md | 27 ++-
> 1 file changed, 14 insertions(+), 13 deletions(-)
>
> diff --git a/gcc/config/aarch64/aarch64.md b/gcc/config/aarch64/aarch64.md
> index baef56a..06256e3 100644
> --- a/gcc/config/aarch64/aarch64.md
> +++ b/gcc/config/aarch64/aarch64.md
> @@ -3349,17 +3349,18 @@
>
> ;; Logical right shift using SISD or Integer instruction
> (define_insn "*aarch64_lshr_sisd_or_int_3"
> - [(set (match_operand:GPI 0 "register_operand" "=w,&w,r")
> + [(set (match_operand:GPI 0 "register_operand" "=r,w,&w,&w")
> (lshiftrt:GPI
> - (match_operand:GPI 1 "register_operand" "w,w,r")
> - (match_operand:QI 2 "aarch64_reg_or_shift_imm_"
> "Us,w,rUs")))]
> + (match_operand:GPI 1 "register_operand" "r,w,w,w")
> + (match_operand:QI 2 "aarch64_reg_or_shift_imm_"
> "rUs,Us,w,0")))]
>""
>"@
> + lsr\t%0, %1, %2
> ushr\t%0, %1, %2
> #
> - lsr\t%0, %1, %2"
> - [(set_attr "simd" "yes,yes,no")
> - (set_attr "type" "neon_shift_imm,neon_shift_reg,shift_reg")]
> + #"
> + [(set_attr "simd" "no,yes,yes,yes")
> + (set_attr "type"
> "shift_reg,neon_shift_imm,neon_shift_reg,neon_shift_reg")]
> )
>
> (define_split
> @@ -3394,18 +3395,18 @@
>
> ;; Arithmetic right shift using SISD or Integer instruction
> (define_insn "*aarch64_ashr_sisd_or_int_3"
> - [(set (match_operand:GPI 0 "register_operand" "=w,&w,&w,r")
> + [(set (match_operand:GPI 0 "register_operand" "=r,w,&w,&w")
> (ashiftrt:GPI
> - (match_operand:GPI 1 "register_operand" "w,w,w,r")
> - (match_operand:QI 2 "aarch64_reg_or_shift_imm_di"
> "Us,w,0,rUs")))]
> + (match_operand:GPI 1 "register_operand" "r,w,w,w")
> + (match_operand:QI 2 "aarch64_reg_or_shift_imm_di"
> "rUs,Us,w,0")))]
>""
>"@
> + asr\t%0, %1, %2
> sshr\t%0, %1, %2
> #
> - #
> - asr\t%0, %1, %2"
> - [(set_attr "simd" "yes,yes,yes,no")
> - (set_attr "type"
> "neon_shift_imm,neon_shift_reg,neon_shift_reg,shift_reg")]
> + #"
> + [(set_attr "simd" "no,yes,yes,yes")
> + (set_attr "type"
> "shift_reg,neon_shift_imm,neon_shift_reg,neon_shift_reg")]
> )
>
> (define_split
> --
> 1.9.1
>
>
