On Tue, Jan 29, 2019 at 2:36 PM Steve Ellcey <[email protected]> wrote:
>
> So the various tests that started failing with r265398 seem to need
> different fixes. This particular fix is for the
> gcc.target/aarch64/lsl_asr_sbfiz.c failure. The problem is that the
> instructions we are trying to match to *ashiftsi_extv_bfiz now have
> explicit subregs in them where they didn't before. The new version
> is:
>
> (set (reg:SI 93)
> (ashift:SI (subreg:SI (sign_extract:DI (subreg:DI (reg:SI 95) 0)
> (const_int 3 [0x3])
> (const_int 0 [0])) 0)
> (const_int 19 [0x13])))
>
>
> The subreg's were not there before. My proposed fix is to add an new
> instruction like *ashiftsi_extv_bfiz but with the subregs. This fixes
> lsl_asr_sbfiz.c. Does this seem like the right way to fix this?
Seems to me rather this should have been simplified to just:
(set (reg:SI 93)
(ashift:SI (sign_extract:SI (reg:SI 95)
(const_int 3 [0x3])
(const_int 0 [0]))
(const_int 19 [0x13])))
Because the two subreg cancel each other out.
This would be a thing to add to simplify-rtx.c.
Thanks,
Andrew
>
> Steve Ellcey
> [email protected]
>
>
> 2018-01-29 Steve Ellcey <[email protected]>
>
> PR rtl-optimization/87763
> * config/aarch64/aarch64.md (*ashiftsi_extv_bfiz_alt):
> New Instruction.
>
> diff --git a/gcc/config/aarch64/aarch64.md
> b/gcc/config/aarch64/aarch64.md
> index b7f6fe0f135..d65230c4837 100644
> --- a/gcc/config/aarch64/aarch64.md
> +++ b/gcc/config/aarch64/aarch64.md
> @@ -5531,6 +5531,22 @@
> [(set_attr "type" "bfx")]
> )
>
> +(define_insn "*ashiftsi_extv_bfiz_alt"
> + [(set (match_operand:SI 0 "register_operand" "=r")
> + (ashift:SI
> + (subreg:SI
> + (sign_extract:DI
> + (subreg:DI (match_operand:SI 1 "register_operand" "r") 0)
> + (match_operand 2 "aarch64_simd_shift_imm_offset_si" "n")
> + (const_int 0))
> + 0)
> + (match_operand 3 "aarch64_simd_shift_imm_si" "n")))]
> + "IN_RANGE (INTVAL (operands[2]) + INTVAL (operands[3]),
> + 1, GET_MODE_BITSIZE (SImode) - 1)"
> + "sbfiz\\t%w0, %w1, %3, %2"
> + [(set_attr "type" "bfx")]
> +)
> +
> ;; When the bit position and width of the equivalent extraction add up
> to 32
> ;; we can use a W-reg LSL instruction taking advantage of the implicit
> ;; zero-extension of the X-reg.
