Re: [PATCH] [x86] Improve ix86_expand_fast_convert_bf_to_sf with new extendbfsf2_1.

[Uros Bizjak <ubizjak@gmail.com>]

On Fri, Dec 2, 2022 at 5:26 AM liuhongt <hongtao.liu@intel.com> wrote:
>
> After supporting extendbfsf2_1, ix86_expand_fast_convert_bf_to_sf can
> be improved with pslld either.
> CONST_INT_P is not handled since constant shift can be optimized off.
>
> Bootstrapped and regtested on x86_64-pc-linux-gnu{-m32,}.
> Ok for trunk?
>
> gcc/ChangeLog:
>
>         * config/i386/i386-expand.cc
>         (ix86_expand_fast_convert_bf_to_sf): Optimized with
>         extendbfsf2_1 for non-CONST_INT_P operand.

Please say: "Use extendbfsf2_1 for nonimmediate operand."
>
> gcc/testsuite/ChangeLog:
>
>         * gcc.target/i386/cbranchbf4.c: New test.

Otherwise OK.

Thanks,
Uros.

> ---
>  gcc/config/i386/i386-expand.cc             | 13 ++++++-------
>  gcc/testsuite/gcc.target/i386/cbranchbf4.c | 15 +++++++++++++++
>  2 files changed, 21 insertions(+), 7 deletions(-)
>  create mode 100644 gcc/testsuite/gcc.target/i386/cbranchbf4.c
>
> diff --git a/gcc/config/i386/i386-expand.cc b/gcc/config/i386/i386-expand.cc
> index d26e7e41445..0bc80c4b178 100644
> --- a/gcc/config/i386/i386-expand.cc
> +++ b/gcc/config/i386/i386-expand.cc
> @@ -24155,14 +24155,13 @@ ix86_expand_fast_convert_bf_to_sf (rtx val)
>        /* FLOAT_EXTEND simplification will fail if VAL is a sNaN.  */
>        ret = gen_reg_rtx (SImode);
>        emit_move_insn (ret, GEN_INT (INTVAL (op) & 0xffff));
> +      emit_insn (gen_ashlsi3 (ret, ret, GEN_INT (16)));
> +      return gen_lowpart (SFmode, ret);
>      }
> -  else
> -    {
> -      ret = gen_reg_rtx (SImode);
> -      emit_insn (gen_zero_extendhisi2 (ret, op));
> -    }
> -  emit_insn (gen_ashlsi3 (ret, ret, GEN_INT (16)));
> -  return gen_lowpart (SFmode, ret);
> +
> +  ret = gen_reg_rtx (SFmode);
> +  emit_insn (gen_extendbfsf2_1 (ret, force_reg (BFmode, val)));
> +  return ret;
>  }
>
>  #include "gt-i386-expand.h"
> diff --git a/gcc/testsuite/gcc.target/i386/cbranchbf4.c b/gcc/testsuite/gcc.target/i386/cbranchbf4.c
> new file mode 100644
> index 00000000000..8241a0c2165
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/cbranchbf4.c
> @@ -0,0 +1,15 @@
> +/* { dg-do compile } */
> +/* { dg-options "-fexcess-precision=16 -O -msse2 -mfpmath=sse" } */
> +/* { dg-final { scan-assembler-times "pslld" 4 } } */
> +
> +char
> +foo (__bf16 a, __bf16 b)
> +{
> +  return a > b;
> +}
> +
> +float
> +foo1 (__bf16 a, __bf16 b, float c, float d)
> +{
> +  return a > b ? c : d;
> +}
> --
> 2.27.0
>