[gcc(refs/users/meissner/heads/work019)] PowerPC: If long double is IEEE 128-bit, map q built-ins to *l instead of *f128.

[Michael Meissner]

https://gcc.gnu.org/g:94cade6a2797e7f275dbaf36a943fe9a21762b53

commit 94cade6a2797e7f275dbaf36a943fe9a21762b53
Author: Michael Meissner <meissner@linux.ibm.com>
Date:   Wed Sep 30 17:33:46 2020 -0400

    PowerPC: If long double is IEEE 128-bit, map q built-ins to *l instead of *f128.
    
    If we map nanq to nanf128 when long double is IEEE, it seems to lose the
    special signaling vs. non-signaling NAN support.  This patch maps the functions
    to the long double version if long double is IEEE 128-bit.
    
    gcc/
    2020-09-30  Michael Meissner  <meissner@linux.ibm.com>
    
            * config/rs6000/rs6000-c.c (rs6000_cpu_cpp_builtins): If long
            double is IEEE-128 map the nanq built-in functions to the long
            double function, not the f128 function.

Diff:
---
 gcc/config/rs6000/rs6000-c.c | 31 ++++++++++++++++++++++++-------
 1 file changed, 24 insertions(+), 7 deletions(-)

diff --git a/gcc/config/rs6000/rs6000-c.c b/gcc/config/rs6000/rs6000-c.c
index cc1e997524e..bee78fcbac4 100644
--- a/gcc/config/rs6000/rs6000-c.c
+++ b/gcc/config/rs6000/rs6000-c.c
@@ -684,15 +684,32 @@ rs6000_cpu_cpp_builtins (cpp_reader *pfile)
       builtin_define ("__builtin_vsx_xvnmsubmsp=__builtin_vsx_xvnmsubsp");
     }
 
-  /* Map the old _Float128 'q' builtins into the new 'f128' builtins.  */
+  /* Map the old _Float128 'q' builtins into the new 'f128' builtins if long
+     double is IBM or 64-bit.
+
+     However, if long double is IEEE 128-bit, map both sets of built-in
+     functions to the normal long double version.  This shows up in nansf128
+     vs. nanf128.  */
   if (TARGET_FLOAT128_TYPE)
     {
-      builtin_define ("__builtin_fabsq=__builtin_fabsf128");
-      builtin_define ("__builtin_copysignq=__builtin_copysignf128");
-      builtin_define ("__builtin_nanq=__builtin_nanf128");
-      builtin_define ("__builtin_nansq=__builtin_nansf128");
-      builtin_define ("__builtin_infq=__builtin_inff128");
-      builtin_define ("__builtin_huge_valq=__builtin_huge_valf128");
+      if (FLOAT128_IEEE_P (TFmode))
+	{
+	  builtin_define ("__builtin_fabsq=__builtin_fabsl");
+	  builtin_define ("__builtin_copysignq=__builtin_copysignl");
+	  builtin_define ("__builtin_nanq=__builtin_nanl");
+	  builtin_define ("__builtin_nansq=__builtin_nansl");
+	  builtin_define ("__builtin_infq=__builtin_infl");
+	  builtin_define ("__builtin_huge_valq=__builtin_huge_vall");
+	}
+      else
+	{
+	  builtin_define ("__builtin_fabsq=__builtin_fabsf128");
+	  builtin_define ("__builtin_copysignq=__builtin_copysignf128");
+	  builtin_define ("__builtin_nanq=__builtin_nanf128");
+	  builtin_define ("__builtin_nansq=__builtin_nansf128");
+	  builtin_define ("__builtin_infq=__builtin_inff128");
+	  builtin_define ("__builtin_huge_valq=__builtin_huge_valf128");
+	}
     }
 
   /* Tell users they can use __builtin_bswap{16,64}.  */