Hi,
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On Wed, Oct 16, 2019 at 04:24:29PM +0000, Yuliang Wang wrote:
> +;; Unpredicated bitwise select.
> +(define_insn "*aarch64_sve2_bsl<mode>"
> + [(set (match_operand:SVE_I 0 "register_operand" "=w, ?&w")
> + (xor:SVE_I
> + (and:SVE_I
> + (xor:SVE_I
> + (match_operand:SVE_I 1 "register_operand" "<bsl_1st>, w")
> + (match_operand:SVE_I 2 "register_operand" "<bsl_2nd>, w"))
> + (match_operand:SVE_I 3 "register_operand" "w, w"))
> + (match_dup BSL_3RD)))]
This isn't canonical RTL. Does combine not simplify this?
Or, rather, it should not be what we canonicalise to: nothing is defined
here.
We normally get something like
Trying 7, 8 -> 9:
7: r127:SI=r130:DI#4^r125:DI#4
REG_DEAD r130:DI
8: r128:SI=r127:SI&0x20000000
REG_DEAD r127:SI
9: r126:SI=r128:SI^r125:DI#4
REG_DEAD r128:SI
REG_DEAD r125:DI
Successfully matched this instruction:
(set (reg:SI 126)
(ior:SI (and:SI (subreg:SI (reg:DI 130) 4)
(const_int 536870912 [0x20000000]))
(and:SI (subreg:SI (reg/v:DI 125 [ yD.2902+-4 ]) 4)
(const_int -536870913 [0xffffffffdfffffff]))))
If the mask is not a constant, we really shouldn't generate a totally
different form. The xor-and-xor form is very hard to handle, too.
Expand currently generates this, because gimple thinks this is simpler.
I think this should be fixed.
Segher
