Re: Ping ^ 2: [PATCH] rs6000: Expand fmod and remainder when built with fast-math [PR97142]

[Bill Schmidt <wschmidt@linux.ibm.com>]

Hi Xionghu,

This looks okay to me.  Recommend maintainers approve.

Thanks!
Bill

On 9/2/21 9:31 PM, Xionghu Luo wrote:
> Resend the patch that addressed Will's comments.
>
>
> fmod/fmodf and remainder/remainderf could be expanded instead of library
> call when fast-math build, which is much faster.
>
> fmodf:
>       fdivs   f0,f1,f2
>       friz    f0,f0
>       fnmsubs f1,f2,f0,f1
>
> remainderf:
>       fdivs   f0,f1,f2
>       frin    f0,f0
>       fnmsubs f1,f2,f0,f1
>
> SPEC2017 Ofast P8LE: 511.povray_r +1.14%,  526.blender_r +1.72%
>
> gcc/ChangeLog:
>
> 2021-09-03  Xionghu Luo  <luoxhu@linux.ibm.com>
>
> 	PR target/97142
> 	* config/rs6000/rs6000.md (fmod<mode>3): New define_expand.
> 	(remainder<mode>3): Likewise.
>
> gcc/testsuite/ChangeLog:
>
> 2021-09-03  Xionghu Luo  <luoxhu@linux.ibm.com>
>
> 	PR target/97142
> 	* gcc.target/powerpc/pr97142.c: New test.
> ---
>   gcc/config/rs6000/rs6000.md                | 36 ++++++++++++++++++++++
>   gcc/testsuite/gcc.target/powerpc/pr97142.c | 35 +++++++++++++++++++++
>   2 files changed, 71 insertions(+)
>   create mode 100644 gcc/testsuite/gcc.target/powerpc/pr97142.c
>
> diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md
> index c8cdc42533c..84820d3b5cb 100644
> --- a/gcc/config/rs6000/rs6000.md
> +++ b/gcc/config/rs6000/rs6000.md
> @@ -4932,6 +4932,42 @@ (define_insn "fre<sd>"
>     [(set_attr "type" "fp")
>      (set_attr "isa" "*,<Fisa>")])
>   
> +(define_expand "fmod<mode>3"
> +  [(use (match_operand:SFDF 0 "gpc_reg_operand"))
> +	(use (match_operand:SFDF 1 "gpc_reg_operand"))
> +	(use (match_operand:SFDF 2 "gpc_reg_operand"))]
> +  "TARGET_HARD_FLOAT
> +  && TARGET_FPRND
> +  && flag_unsafe_math_optimizations"
> +{
> +  rtx div = gen_reg_rtx (<MODE>mode);
> +  emit_insn (gen_div<mode>3 (div, operands[1], operands[2]));
> +
> +  rtx friz = gen_reg_rtx (<MODE>mode);
> +  emit_insn (gen_btrunc<mode>2 (friz, div));
> +
> +  emit_insn (gen_nfms<mode>4 (operands[0], operands[2], friz, operands[1]));
> +  DONE;
> + })
> +
> +(define_expand "remainder<mode>3"
> +  [(use (match_operand:SFDF 0 "gpc_reg_operand"))
> +	(use (match_operand:SFDF 1 "gpc_reg_operand"))
> +	(use (match_operand:SFDF 2 "gpc_reg_operand"))]
> +  "TARGET_HARD_FLOAT
> +  && TARGET_FPRND
> +  && flag_unsafe_math_optimizations"
> +{
> +  rtx div = gen_reg_rtx (<MODE>mode);
> +  emit_insn (gen_div<mode>3 (div, operands[1], operands[2]));
> +
> +  rtx frin = gen_reg_rtx (<MODE>mode);
> +  emit_insn (gen_round<mode>2 (frin, div));
> +
> +  emit_insn (gen_nfms<mode>4 (operands[0], operands[2], frin, operands[1]));
> +  DONE;
> + })
> +
>   (define_insn "*rsqrt<mode>2"
>     [(set (match_operand:SFDF 0 "gpc_reg_operand" "=<Ff>,wa")
>   	(unspec:SFDF [(match_operand:SFDF 1 "gpc_reg_operand" "<Ff>,wa")]
> diff --git a/gcc/testsuite/gcc.target/powerpc/pr97142.c b/gcc/testsuite/gcc.target/powerpc/pr97142.c
> new file mode 100644
> index 00000000000..e5306eb681b
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/powerpc/pr97142.c
> @@ -0,0 +1,35 @@
> +/* { dg-do compile } */
> +/* { dg-options "-Ofast" } */
> +
> +#include <math.h>
> +
> +float test1 (float x, float y)
> +{
> +  return fmodf (x, y);
> +}
> +
> +double test2 (double x, double y)
> +{
> +  return fmod (x, y);
> +}
> +
> +float test3 (float x, float y)
> +{
> +  return remainderf (x, y);
> +}
> +
> +double test4 (double x, double y)
> +{
> +  return remainder (x, y);
> +}
> +
> +/* { dg-final { scan-assembler-not {\mbl fmod\M} } } */
> +/* { dg-final { scan-assembler-not {\mbl fmodf\M} } } */
> +/* { dg-final { scan-assembler-not {\mbl remainder\M} } } */
> +/* { dg-final { scan-assembler-not {\mbl remainderf\M} } } */
> +/* { dg-final { scan-assembler-times {\mfdiv\M} 2 } } */
> +/* { dg-final { scan-assembler-times {\mfdivs\M} 2 } } */
> +/* { dg-final { scan-assembler-times {\mfnmsub\M} 2 } } */
> +/* { dg-final { scan-assembler-times {\mfnmsubs\M} 2 } } */
> +/* { dg-final { scan-assembler-times {\mfriz\M} 2 } } */
> +/* { dg-final { scan-assembler-times {\mfrin\M} 2 } } */