[PATCH, rs6000] Implemented f[min/max]_optab by xs[min/max]dp [PR103605]

[HAO CHEN GUI via Gcc-patches]

Hi,
  This patch implements optab f[min/max]_optab by xs[min/max]dp on rs6000.
Tests show that outputs of xs[min/max]dp are consistent with the standard
of C99 fmin/max.

  Bootstrapped and tested on ppc64 Linux BE and LE with no regressions.
Is this okay for trunk? Any recommendations? Thanks a lot.

ChangeLog
2022-05-09 Haochen Gui <guih...@linux.ibm.com>

gcc/
        PR target/103605
        * rs6000.md (unspec): Add UNSPEC_FMAX and UNSPEC_FMIN.
        (fminmax): New.
        (minmax_op): Likewise.
        (<fminmax><mode>3): New pattern.  Implemented by UNSPEC_FMAX and
        UNSPEC_FMIN.

gcc/testsuite/
        PR target/103605
        * gcc.dg/pr103605.c: New.

patch.diff
diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md
index fdfbc6566a5..8aae3e80bcd 100644
--- a/gcc/config/rs6000/rs6000.md
+++ b/gcc/config/rs6000/rs6000.md
@@ -158,6 +158,8 @@ (define_c_enum "unspec"
    UNSPEC_HASHCHK
    UNSPEC_XXSPLTIDP_CONST
    UNSPEC_XXSPLTIW_CONST
+   UNSPEC_FMAX
+   UNSPEC_FMIN
   ])

 ;;
@@ -5350,6 +5352,25 @@ (define_insn_and_split "*s<minmax><mode>3_fpr"
   DONE;
 })

+
+(define_int_iterator FMINMAX [UNSPEC_FMAX UNSPEC_FMIN])
+
+(define_int_attr fminmax [(UNSPEC_FMAX "fmax")
+                         (UNSPEC_FMIN "fmin")])
+
+(define_int_attr  minmax_op [(UNSPEC_FMAX "max")
+                                (UNSPEC_FMIN "min")])
+
+(define_insn "<fminmax><mode>3"
+  [(set (match_operand:SFDF 0 "vsx_register_operand" "=<Fv>")
+       (unspec:SFDF [(match_operand:SFDF 1 "vsx_register_operand" "<Fv>")
+                     (match_operand:SFDF 2 "vsx_register_operand" "<Fv>")]
+                     FMINMAX))]
+"TARGET_VSX"
+"xs<minmax_op>dp %x0,%x1,%x2"
+[(set_attr "type" "fp")]
+)
+
 (define_expand "mov<mode>cc"
    [(set (match_operand:GPR 0 "gpc_reg_operand")
         (if_then_else:GPR (match_operand 1 "comparison_operator")
diff --git a/gcc/testsuite/gcc.target/powerpc/pr103605.c 
b/gcc/testsuite/gcc.target/powerpc/pr103605.c
new file mode 100644
index 00000000000..a40da064742
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/pr103605.c
@@ -0,0 +1,27 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target powerpc_vsx_ok } */
+/* { dg-options "-O1 -mvsx" } */
+/* { dg-final { scan-assembler-times "xsmaxdp" 2 } } */
+/* { dg-final { scan-assembler-times "xsmindp" 2 } } */
+
+#include <math.h>
+
+double test1 (double d0, double d1)
+{
+  return fmin (d0, d1);
+}
+
+float test2 (float d0, float d1)
+{
+  return fmin (d0, d1);
+}
+
+double test3 (double d0, double d1)
+{
+  return fmax (d0, d1);
+}
+
+float test4 (float d0, float d1)
+{
+  return fmax (d0, d1);
+}