[gcc(refs/users/meissner/heads/work055)] Add IEEE 128-bit min/max support on PowerPC.

[Michael Meissner <meissner@gcc.gnu.org>]

https://gcc.gnu.org/g:2b254cb79d6c67961f2b77ba4bedff84b55a0661

commit 2b254cb79d6c67961f2b77ba4bedff84b55a0661
Author: Michael Meissner <meissner@linux.ibm.com>
Date:   Mon Jun 7 23:04:00 2021 -0400

    Add IEEE 128-bit min/max support on PowerPC.
    
    This patch adds the support for the IEEE 128-bit floating point C minimum and
    maximum instructions.  The next patch will add the support for using the
    compare and set mask instruction to implement conditional moves.
    
    This patch does not try to re-use the code used for SF/DF min/max
    support.  It defines a separate insn for the IEEE 128-bit support.  It
    uses the code iterator <minmax> to simplify adding both operations.
    
    GCC will not convert ternary operations into using min/max instructions
    provided in this patch unless the user uses -Ofast or similar switches due to
    issues with NaNs.  The next patch that adds conditional move instructions will
    enable the ternary conversion in many cases.
    
    The float128-minmax.c test generates the xsmincqp and xsmaxcqp
    instructions on power10.  This patch adjusts the test to accomidate this.
    
    gcc/
    2021-06-07  Michael Meissner  <meissner@linux.ibm.com>
    
            * config/rs6000/rs6000.c (rs6000_emit_minmax): Add support for ISA
            3.1 IEEE 128-bit floating point xsmaxcqp and xsmincqp
            instructions.
            * config/rs6000/rs6000.md (s<minmax><mode>3, IEEE128 iterator):
            New insns.
    
    gcc/testsuite/
    2021-06-07  Michael Meissner  <meissner@linux.ibm.com>
    
            * gcc.target/powerpc/float128-minmax-2.c: New test.
            * gcc.target/powerpc/float128-minmax.c: Adjust expected code for
            power10.
            * lib/target-supports.exp (check_effective_target_has_arch_pwr10):
            New target support.

Diff:
---
 gcc/config/rs6000/rs6000.c                           |  3 ++-
 gcc/config/rs6000/rs6000.md                          | 11 +++++++++++
 gcc/testsuite/gcc.target/powerpc/float128-minmax-2.c | 15 +++++++++++++++
 gcc/testsuite/gcc.target/powerpc/float128-minmax.c   |  7 +++++--
 gcc/testsuite/lib/target-supports.exp                | 10 ++++++++++
 5 files changed, 43 insertions(+), 3 deletions(-)

diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index b01bb5c8191..1651788df6a 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -16103,7 +16103,8 @@ 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))
+	  || (TARGET_POWER10 && TARGET_FLOAT128_HW && FLOAT128_IEEE_P (mode))))
     {
       emit_insn (gen_rtx_SET (dest, gen_rtx_fmt_ee (code, mode, op0, op1)));
       return;
diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md
index 3f59b544f6a..064c3a2d9d6 100644
--- a/gcc/config/rs6000/rs6000.md
+++ b/gcc/config/rs6000/rs6000.md
@@ -5214,6 +5214,17 @@
 }
   [(set_attr "type" "fp")])
 
+;; Min/max for ISA 3.1 IEEE 128-bit floating point
+(define_insn "s<minmax><mode>3"
+  [(set (match_operand:IEEE128 0 "altivec_register_operand" "=v")
+	(fp_minmax:IEEE128
+	 (match_operand:IEEE128 1 "altivec_register_operand" "v")
+	 (match_operand:IEEE128 2 "altivec_register_operand" "v")))]
+  "TARGET_POWER10"
+  "xs<minmax>cqp %0,%1,%2"
+  [(set_attr "type" "vecfloat")
+   (set_attr "size" "128")])
+
 ;; The conditional move instructions allow us to perform max and min operations
 ;; even when we don't have the appropriate max/min instruction using the FSEL
 ;; instruction.
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} } } */
diff --git a/gcc/testsuite/gcc.target/powerpc/float128-minmax.c b/gcc/testsuite/gcc.target/powerpc/float128-minmax.c
index fe397518f2f..cdff6943bc3 100644
--- a/gcc/testsuite/gcc.target/powerpc/float128-minmax.c
+++ b/gcc/testsuite/gcc.target/powerpc/float128-minmax.c
@@ -1,7 +1,7 @@
 /* { dg-do compile { target lp64 } } */
 /* { dg-require-effective-target powerpc_p9vector_ok } */
 /* { dg-require-effective-target float128 } */
-/* { dg-options "-mpower9-vector -O2 -ffast-math" } */
+/* { dg-options "-O2 -ffast-math" } */
 
 #ifndef TYPE
 #define TYPE _Float128
@@ -12,5 +12,8 @@
 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     {\mxscmpuqp\M} } } */
+/* Note power10 has native min/max instructions.  */
+/* { dg-final { scan-assembler     {\mxscmpuqp\M} } target { ! has_arch_pwr10 } } */
+/* { dg-final { scan-assembler     {\mxsmincqp\M} } target { has_arch_pwr10 } } */
+/* { dg-final { scan-assembler     {\mxsmaxcqp\M} } target { has_arch_pwr10 } } */
 /* { dg-final { scan-assembler-not {\mbl\M}       } } */
diff --git a/gcc/testsuite/lib/target-supports.exp b/gcc/testsuite/lib/target-supports.exp
index 7f78c5593ac..789723fb287 100644
--- a/gcc/testsuite/lib/target-supports.exp
+++ b/gcc/testsuite/lib/target-supports.exp
@@ -6127,6 +6127,16 @@ proc check_effective_target_has_arch_pwr9 { } {
 	}]
 }
 
+proc check_effective_target_has_arch_pwr10 { } {
+	return [check_no_compiler_messages arch_pwr10 assembly {
+		#ifndef _ARCH_PWR10
+		#error does not have power10 support.
+		#else
+		/* "has power10 support" */
+		#endif
+	}]
+}
+
 # Return 1 if this is a PowerPC target supporting -mcpu=power10.
 # Limit this to 64-bit linux systems for now until other targets support
 # power10.