[v2] MIPS: Add MIN/MAX.fmt instructions support for MIPS R6

This patch adds the smin/smax RTL mode for the
min/max.fmt instructions.

Also, since the min/max.fmt instrucions applies to the
IEEE 754-2008 "minNum" and "maxNum" operations, this
patch also provides the new "fmin<mode>3" and
"fmax<mode>3" modes.

gcc/ChangeLog:

	* config/mips/i6400.md (i6400_fpu_minmax): New
	define_insn_reservation.
	* config/mips/mips.h (ISA_HAS_FMIN_FMAX): Define new macro.
	* config/mips/mips.md (UNSPEC_FMIN): New unspec.
	(UNSPEC_FMAX): Same as above.
	(type): Add fminmax.
	(smin<mode>3): Generates MIN.fmt instructions.
	(smax<mode>3): Generates MAX.fmt instructions.
	(fmin<mode>3): Generates MIN.fmt instructions.
	(fmax<mode>3): Generates MAX.fmt instructions.
	* config/mips/p6600.md (p6600_fpu_fabs): Include fminmax
	type.

gcc/testsuite/ChangeLog:

	* gcc.target/mips/mips-minmax.c: New test for MIPS R6.
---
 gcc/config/mips/i6400.md                    |  6 +++
 gcc/config/mips/mips.h                      |  2 +
 gcc/config/mips/mips.md                     | 50 ++++++++++++++++++++-
 gcc/config/mips/p6600.md                    |  2 +-
 gcc/testsuite/gcc.target/mips/mips-minmax.c | 40 +++++++++++++++++
 5 files changed, 97 insertions(+), 3 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/mips/mips-minmax.c

Jie Mei <jie.mei@oss.cipunited.com> 于2024年3月25日周一 17:46写道：
>
> This patch adds the smin/smax RTL mode for the
> min/max.fmt instructions.
>
> Also, since the min/max.fmt instrucions applies to the
> IEEE 754-2008 "minNum" and "maxNum" operations, this
> patch also provides the new "fmin<mode>3" and
> "fmax<mode>3" modes.
>
> gcc/ChangeLog:
>
>         * config/mips/i6400.md (i6400_fpu_minmax): New
>         define_insn_reservation.
>         * config/mips/mips.h (ISA_HAS_FMIN_FMAX): Define new macro.
>         * config/mips/mips.md (UNSPEC_FMIN): New unspec.
>         (UNSPEC_FMAX): Same as above.
>         (type): Add fminmax.
>         (smin<mode>3): Generates MIN.fmt instructions.
>         (smax<mode>3): Generates MAX.fmt instructions.
>         (fmin<mode>3): Generates MIN.fmt instructions.
>         (fmax<mode>3): Generates MAX.fmt instructions.
>         * config/mips/p6600.md (p6600_fpu_fabs): Include fminmax
>         type.
>
> gcc/testsuite/ChangeLog:
>
>         * gcc.target/mips/mips-minmax.c: New test for MIPS R6.
> ---
>  gcc/config/mips/i6400.md                    |  6 +++
>  gcc/config/mips/mips.h                      |  2 +
>  gcc/config/mips/mips.md                     | 50 ++++++++++++++++++++-
>  gcc/config/mips/p6600.md                    |  2 +-
>  gcc/testsuite/gcc.target/mips/mips-minmax.c | 40 +++++++++++++++++
>  5 files changed, 97 insertions(+), 3 deletions(-)
>  create mode 100644 gcc/testsuite/gcc.target/mips/mips-minmax.c
>
> diff --git a/gcc/config/mips/i6400.md b/gcc/config/mips/i6400.md
> index 9f216fe0210..d6f691ee217 100644
> --- a/gcc/config/mips/i6400.md
> +++ b/gcc/config/mips/i6400.md
> @@ -219,6 +219,12 @@
>         (eq_attr "type" "fabs,fneg,fmove"))
>    "i6400_fpu_short, i6400_fpu_apu")
>
> +;; min, max
> +(define_insn_reservation "i6400_fpu_minmax" 2
> +  (and (eq_attr "cpu" "i6400")
> +       (eq_attr "type" "fminmax"))
> +  "i6400_fpu_short+i6400_fpu_logic")
> +
>  ;; fadd, fsub, fcvt
>  (define_insn_reservation "i6400_fpu_fadd" 4
>    (and (eq_attr "cpu" "i6400")
> diff --git a/gcc/config/mips/mips.h b/gcc/config/mips/mips.h
> index 7145d23c650..5ce984ac99b 100644
> --- a/gcc/config/mips/mips.h
> +++ b/gcc/config/mips/mips.h
> @@ -1259,6 +1259,8 @@ struct mips_cpu_info {
>  #define ISA_HAS_9BIT_DISPLACEMENT      (mips_isa_rev >= 6              \
>                                          || ISA_HAS_MIPS16E2)
>
> +#define ISA_HAS_FMIN_FMAX      (mips_isa_rev >= 6)
> +
>  /* ISA has data indexed prefetch instructions.  This controls use of
>     'prefx', along with TARGET_HARD_FLOAT and TARGET_DOUBLE_FLOAT.
>     (prefx is a cop1x instruction, so can only be used if FP is
> diff --git a/gcc/config/mips/mips.md b/gcc/config/mips/mips.md
> index b0fb5850a9e..26f758c90dd 100644
> --- a/gcc/config/mips/mips.md
> +++ b/gcc/config/mips/mips.md
> @@ -97,6 +97,10 @@
>    UNSPEC_GET_FCSR
>    UNSPEC_SET_FCSR
>
> +  ;; Floating-point unspecs.
> +  UNSPEC_FMIN
> +  UNSPEC_FMAX
> +
>    ;; HI/LO moves.
>    UNSPEC_MFHI
>    UNSPEC_MTHI
> @@ -370,6 +374,7 @@
>  ;; frsqrt       floating point reciprocal square root
>  ;; frsqrt1      floating point reciprocal square root step1
>  ;; frsqrt2      floating point reciprocal square root step2
> +;; fminmax      floating point min/max
>  ;; dspmac       DSP MAC instructions not saturating the accumulator
>  ;; dspmacsat    DSP MAC instructions that saturate the accumulator
>  ;; accext       DSP accumulator extract instructions
> @@ -387,8 +392,8 @@
>     prefetch,prefetchx,condmove,mtc,mfc,mthi,mtlo,mfhi,mflo,const,arith,logical,
>     shift,slt,signext,clz,pop,trap,imul,imul3,imul3nc,imadd,idiv,idiv3,move,
>     fmove,fadd,fmul,fmadd,fdiv,frdiv,frdiv1,frdiv2,fabs,fneg,fcmp,fcvt,fsqrt,
> -   frsqrt,frsqrt1,frsqrt2,dspmac,dspmacsat,accext,accmod,dspalu,dspalusat,
> -   multi,atomic,syncloop,nop,ghost,multimem,
> +   frsqrt,frsqrt1,frsqrt2,fminmax,dspmac,dspmacsat,accext,accmod,dspalu,
> +   dspalusat,multi,atomic,syncloop,nop,ghost,multimem,
>     simd_div,simd_fclass,simd_flog2,simd_fadd,simd_fcvt,simd_fmul,simd_fmadd,
>     simd_fdiv,simd_bitins,simd_bitmov,simd_insert,simd_sld,simd_mul,simd_fcmp,
>     simd_fexp2,simd_int_arith,simd_bit,simd_shift,simd_splat,simd_fill,
> @@ -7971,6 +7976,47 @@
>    [(set_attr "move_type" "load")
>     (set_attr "insn_count" "2")])
>
> +;;
> +;;  Float point MIN/MAX
> +;;
> +
> +(define_insn "smin<mode>3"
> +  [(set (match_operand:SCALARF 0 "register_operand" "=f")
> +       (smin:SCALARF (match_operand:SCALARF 1 "register_operand" "f")
> +                     (match_operand:SCALARF 2 "register_operand" "f")))]
> +  "ISA_HAS_FMIN_FMAX"
> +  "min.<fmt>\t%0,%1,%2"
> +  [(set_attr "type" "fminmax")
> +   (set_attr "mode" "<UNITMODE>")])
> +
> +(define_insn "smax<mode>3"
> +  [(set (match_operand:SCALARF 0 "register_operand" "=f")
> +       (smax:SCALARF (match_operand:SCALARF 1 "register_operand" "f")
> +                     (match_operand:SCALARF 2 "register_operand" "f")))]
> +  "ISA_HAS_FMIN_FMAX"
> +  "max.<fmt>\t%0,%1,%2"
> +  [(set_attr "type" "fminmax")
> +  (set_attr "mode" "<UNITMODE>")])
> +
> +(define_insn "fmin<mode>3"
> +  [(set (match_operand:SCALARF 0 "register_operand" "=f")
> +       (unspec:SCALARF [(use (match_operand:SCALARF 1 "register_operand" "f"))
> +                        (use (match_operand:SCALARF 2 "register_operand" "f"))]
> +                       UNSPEC_FMIN))]
> +  "ISA_HAS_FMIN_FMAX"
> +  "min.<fmt>\t%0,%1,%2"
> +  [(set_attr "type" "fminmax")
> +   (set_attr "mode" "<UNITMODE>")])
> +
> +(define_insn "fmax<mode>3"
> +  [(set (match_operand:SCALARF 0 "register_operand" "=f")
> +       (unspec:SCALARF [(use (match_operand:SCALARF 1 "register_operand" "f"))
> +                        (use (match_operand:SCALARF 2 "register_operand" "f"))]
> +                       UNSPEC_FMAX))]
> +  "ISA_HAS_FMIN_FMAX"
> +  "max.<fmt>\t%0,%1,%2"
> +  [(set_attr "type" "fminmax")
> +  (set_attr "mode" "<UNITMODE>")])
>
>  ;; 2 HI loads are joined.
>  (define_peephole2
> diff --git a/gcc/config/mips/p6600.md b/gcc/config/mips/p6600.md
> index a9e3262cc18..c502f0eb5c6 100644
> --- a/gcc/config/mips/p6600.md
> +++ b/gcc/config/mips/p6600.md
> @@ -170,7 +170,7 @@
>  ;; fabs, fneg, fcmp

add `fminmax` here?


>  (define_insn_reservation "p6600_fpu_fabs" 2
>    (and (eq_attr "cpu" "p6600")
> -       (ior (eq_attr "type" "fabs,fneg,fcmp,fmove")
> +       (ior (eq_attr "type" "fabs,fneg,fcmp,fmove,fminmax")
>            (and (eq_attr "type" "condmove")
>                 (eq_attr "mode" "SF,DF"))))
>    "p6600_fpu_short, p6600_fpu_apu")
> diff --git a/gcc/testsuite/gcc.target/mips/mips-minmax.c b/gcc/testsuite/gcc.target/mips/mips-minmax.c
> new file mode 100644
> index 00000000000..087ed299d8f
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/mips/mips-minmax.c
> @@ -0,0 +1,40 @@
> +/* { dg-do compile } */
> +/* { dg-options "-mhard-float -fno-finite-math-only -march=mips32r6" } */
> +/* { dg-skip-if "code quality test" { *-*-* } { "-O0" } { "" } } */
> +
> +/* Test MIN.D.  */
> +
> +/* { dg-final { scan-assembler "\tmin\\.d\t" } } */
> +double
> +test01 (double x, double y)
> +{
> +  return __builtin_fmin (x, y);
> +}
> +
> +/* Test MIN.S.  */
> +
> +/* { dg-final { scan-assembler "\tmin\\.s\t" } } */
> +float
> +test02 (float x, float y)
> +{
> +  return __builtin_fminf (x, y);
> +}
> +
> +/* Test MAX.D.  */
> +
> +/* { dg-final { scan-assembler "\tmax\\.d\t" } } */
> +double
> +test03 (double x, double y)
> +{
> +  return __builtin_fmax (x, y);
> +}
> +
> +/* Test MAX.S.  */
> +
> +/* { dg-final { scan-assembler "\tmax\\.s\t" } } */
> +float
> +test04 (float x, float y)
> +{
> +  return __builtin_fmaxf (x, y);
> +}
> +

With -ffinite-math-only -fno-signed-zeros, it does work with
    x >= y ? x : y
while without `-ffinite-math-only -fno-signed-zeros`, it cannot.
@Xi Ruoyao Is it expected by IEEE?


And `fmaxf` is also expanded to fmax.
#include <math.h>
float x (float a1, float a2) {
    return fmaxf (a1, a2);
}

I think that we should add such a testcase.


> --
> 2.43.0

On Tue, 2024-03-26 at 11:15 +0800, YunQiang Su wrote:

/* snip */

> With -ffinite-math-only -fno-signed-zeros, it does work with
>     x >= y ? x : y
> while without `-ffinite-math-only -fno-signed-zeros`, it cannot.
> @Xi Ruoyao Is it expected by IEEE?

When y is (quiet) NaN and x is not, fmax(x, y) should produce x but x >=
y ? x : y should produce y.  Thus -ffinite-math-only is needed.

When x is +0.0 and y is -0.0, x >= y ? x : y should produce +0.0 but
fmax(x, y) may produce +0.0 or -0.0 (IEEE allows both and I don't see a
more strict requirement in MIPS 6.06 manual either).  Thus -fno-signed-
zeros is needed.