[PATCH 3/4] PowerPC: Add power10 xsmaxcqp/xsmincqp support

[Michael Meissner <meissner@linux.ibm.com>]

PowerPC: Add power10 xsmaxcqp/xsmincqp support.

This patch adds support for the ISA 3.1 (power10) IEEE 128-bit "C" minimum and
maximum functions.  Because of the NaN differences, the built-in functions will
only generate these instructions if -ffast-math is used until the conditional
move support is added in the next patch.

I have built compilers on a little endian power9 Linux system with all 4
patches applied.  I did bootstrap builds and ran the testsuite, with no
regressions.  Previous versions of the patch was also tested on a little endian
power8 Linux system.  I would like to check this patch into the master branch
for GCC 11.  At this time, I do not anticipate needing to backport these
changes to GCC 10.3.


gcc/
2020-08-26  Michael Meissner  <meissner@linux.ibm.com>

	* config/rs6000/rs6000.h (FLOAT128_IEEE_MINMAX_P): New helper
	macro.
	* config/rs6000/rs6000.md (FSCALAR): New mode iterator for floating
	point scalars.
	(Fm): New mode attribute for floating point scalars.
	(s<minmax><mode>): Add support for the ISA 3.1 IEEE 128-bit
	minimum and maximum instructions.
	(s<minmax><mode>3_vsx): Add support for the ISA 3.1 IEEE 128-bit
	minimum and maximum instructions.

gcc/testsuite/
2020-08-26  Michael Meissner  <meissner@linux.ibm.com>

	* gcc.target/powerpc/float128-minmax-2.c: New test.

---
 gcc/config/rs6000/rs6000.c                    |  3 +-
 gcc/config/rs6000/rs6000.h                    |  4 +++
 gcc/config/rs6000/rs6000.md                   | 28 +++++++++++++++----
 .../gcc.target/powerpc/float128-minmax-2.c    | 15 ++++++++++
 4 files changed, 43 insertions(+), 7 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/powerpc/float128-minmax-2.c

diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index 6324f930628..05eb141a2cd 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -15445,7 +15445,8 @@ rs6000_emit_minmax (rtx dest, enum rtx_code code, rtx op0, rtx op1)
   /* VSX/altivec have direct min/max insns.  */
   if ((code == SMAX || code == SMIN)
       && (VECTOR_UNIT_ALTIVEC_OR_VSX_P (mode)
-	  || (mode == SFmode && VECTOR_UNIT_VSX_P (DFmode))))
+	  || (mode == SFmode && VECTOR_UNIT_VSX_P (DFmode))
+	  || FLOAT128_IEEE_MINMAX_P (mode)))
     {
       emit_insn (gen_rtx_SET (dest, gen_rtx_fmt_ee (code, mode, op0, op1)));
       return;
diff --git a/gcc/config/rs6000/rs6000.h b/gcc/config/rs6000/rs6000.h
index bbd8060e143..b504aaa0199 100644
--- a/gcc/config/rs6000/rs6000.h
+++ b/gcc/config/rs6000/rs6000.h
@@ -345,6 +345,10 @@ extern const char *host_detect_local_cpu (int argc, const char **argv);
    || ((MODE) == TDmode)						\
    || (!TARGET_FLOAT128_TYPE && FLOAT128_IEEE_P (MODE)))
 
+/* Macro whether the float128 min/max instructions are enabled.  */
+#define FLOAT128_IEEE_MINMAX_P(MODE)					\
+  (TARGET_POWER10 && TARGET_FLOAT128_HW && FLOAT128_IEEE_P (MODE))
+
 /* Return true for floating point that does not use a vector register.  */
 #define SCALAR_FLOAT_MODE_NOT_VECTOR_P(MODE)				\
   (SCALAR_FLOAT_MODE_P (MODE) && !FLOAT128_VECTOR_P (MODE))
diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md
index 43b620ae1c0..006e60f09bc 100644
--- a/gcc/config/rs6000/rs6000.md
+++ b/gcc/config/rs6000/rs6000.md
@@ -789,6 +789,18 @@ (define_code_attr     minmax	[(smin "min")
 (define_code_attr     SMINMAX	[(smin "SMIN")
 				 (smax "SMAX")])
 
+;; Mode iterator for scalar binary floating point operations
+(define_mode_iterator FSCALAR [SF
+			       DF
+			       (KF "FLOAT128_IEEE_MINMAX_P (KFmode)")
+			       (TF "FLOAT128_IEEE_MINMAX_P (TFmode)")])
+
+;; Constraints to use for scalar FP operations
+(define_mode_attr Fm [(SF "wa")
+		      (DF "wa")
+		      (TF "v")
+		      (KF "v")])
+
 ;; Iterator to optimize the following cases:
 ;;	D-form load to FPR register & move to Altivec register
 ;;	Move Altivec register to FPR register and store
@@ -5142,9 +5154,9 @@ (define_insn "copysign<mode>3_fcpsgn"
 ;; to allow either DF/SF to use only traditional registers.
 
 (define_expand "s<minmax><mode>3"
-  [(set (match_operand:SFDF 0 "gpc_reg_operand")
-	(fp_minmax:SFDF (match_operand:SFDF 1 "gpc_reg_operand")
-			(match_operand:SFDF 2 "gpc_reg_operand")))]
+  [(set (match_operand:FSCALAR 0 "gpc_reg_operand")
+	(fp_minmax:FSCALAR (match_operand:FSCALAR 1 "gpc_reg_operand")
+			   (match_operand:FSCALAR 2 "gpc_reg_operand")))]
   "TARGET_MINMAX"
 {
   rs6000_emit_minmax (operands[0], <SMINMAX>, operands[1], operands[2]);
@@ -5152,11 +5164,15 @@ (define_expand "s<minmax><mode>3"
 })
 
 (define_insn "*s<minmax><mode>3_vsx"
-  [(set (match_operand:SFDF 0 "vsx_register_operand" "=<Fv>")
-	(fp_minmax:SFDF (match_operand:SFDF 1 "vsx_register_operand" "<Fv>")
-			(match_operand:SFDF 2 "vsx_register_operand" "<Fv>")))]
+  [(set (match_operand:FSCALAR 0 "vsx_register_operand" "=<Fm>")
+	(fp_minmax:FSCALAR
+	 (match_operand:FSCALAR 1 "vsx_register_operand" "<Fm>")
+	 (match_operand:FSCALAR 2 "vsx_register_operand" "<Fm>")))]
   "TARGET_VSX && TARGET_HARD_FLOAT"
 {
+  if (FLOAT128_IEEE_P (<MODE>mode))
+    return "xs<minmax>cqp %0,%1,%2";
+
   return (TARGET_P9_MINMAX
 	  ? "xs<minmax>cdp %x0,%x1,%x2"
 	  : "xs<minmax>dp %x0,%x1,%x2");
diff --git a/gcc/testsuite/gcc.target/powerpc/float128-minmax-2.c b/gcc/testsuite/gcc.target/powerpc/float128-minmax-2.c
new file mode 100644
index 00000000000..c71ba08c9f8
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/float128-minmax-2.c
@@ -0,0 +1,15 @@
+/* { dg-require-effective-target ppc_float128_hw } */
+/* { dg-require-effective-target power10_ok } */
+/* { dg-options "-mdejagnu-cpu=power10 -O2 -ffast-math" } */
+
+#ifndef TYPE
+#define TYPE _Float128
+#endif
+
+/* Test that the fminf128/fmaxf128 functions generate if/then/else and not a
+   call.  */
+TYPE f128_min (TYPE a, TYPE b) { return __builtin_fminf128 (a, b); }
+TYPE f128_max (TYPE a, TYPE b) { return __builtin_fmaxf128 (a, b); }
+
+/* { dg-final { scan-assembler {\mxsmaxcqp\M} } } */
+/* { dg-final { scan-assembler {\mxsmincqp\M} } } */
-- 
2.22.0


-- 
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meissner@linux.ibm.com, phone: +1 (978) 899-4797