[gcc(refs/users/meissner/heads/work043)] Allow __ibm128 on older PowerPC systems.

[Michael Meissner]

https://gcc.gnu.org/g:416004060488efade7be62f5749699b653e8237c

commit 416004060488efade7be62f5749699b653e8237c
Author: Michael Meissner <meissner@linux.ibm.com>
Date:   Tue Mar 30 14:24:28 2021 -0400

    Allow __ibm128 on older PowerPC systems.
    
    In a previous patch, I added code to ibm-ldouble.c to use __builtin_pack_ibm128
    if long double is IEEE 128-bit and continue to use __builtin_pack_longdouble
    if long double is IBM extended double.  This code was needed because
    __builtin_pack_ibm128 is not available unless the __ibm128 keyword is
    availabe.  In the current code, __ibm128 is only enabled if we have support for
    both IBM and IEEE 128-bit long double.
    
    Segher suggested that instead I should make __ibm128, __builtin_pack_ibm128,
    and __builtin_unpack_ibm128 available on older systems that don't support IEEE
    128-bit floating point but does support the IBM extended double floating point.
    
    This patch changes the code so that __ibm128 is now exported if either
    long double uses the IBM extended double format, or IEEE 128-bit floating
    point is available.
    
    I changed the internal built-in types from float128 to ibm128, since the
    only built-in functions that use this are __builtin_pack_ibm128 and
    __builtin_unpack_ibm128, and the new name matches the function.
    
    gcc/
    2021-03-30  Michael Meissner  <meissner@linux.ibm.com>
    
            * config/rs6000/rs6000-builtin.def (BU_IBM128_2): Rename
            RS6000_BTM_IBM128 from RS6000_BTM_FLOAT128.
            * config/rs6000/rs6000-call.c (rs6000_invalid_builtin): Update
            error message for __ibm128 built-in functions.
            (rs6000_init_builtins): Create the __ibm128 keyword on older
            systems where long double uses the IBM extended double format,
            even if they don't support IEEE 128-bit floating point.
            * config/rs6000/rs6000.c (rs6000_builtin_mask_calculate): Rename
            RS6000_BTM_IBM128 from RS6000_BTM_FLOAT128.
            (rs6000_builtin_mask_names): Rename RS6000_BTM_IBM128 from
            RS6000_BTM_FLOAT128.
            * config/rs6000/rs6000.h (TARGET_IBM128): New macro.
            (RS6000_BTM_IBM128): Rename from RS6000_BTM_FLOAT128.
            (RS6000_BTM_COMMON): Rename RS6000_BTM_IBM128 from
            RS6000_BTM_FLOAT128.

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 06b3bc0df33..4950d02ac8f 100644
--- a/gcc/config/rs6000/rs6000-c.c
+++ b/gcc/config/rs6000/rs6000-c.c
@@ -686,15 +686,32 @@ 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}.  */