[gcc(refs/users/meissner/heads/work027)] PowerPC: Allow __ibm128 on older systems.

[Michael Meissner]

https://gcc.gnu.org/g:1e0c1e2c8c7ddbb08a00e1f3c1afece1b67db697

commit 1e0c1e2c8c7ddbb08a00e1f3c1afece1b67db697
Author: Michael Meissner <meissner@linux.ibm.com>
Date:   Sun Nov 15 00:31:25 2020 -0500

    PowerPC: Allow __ibm128 on older systems.
    
    In a patch I submitted for libgcc/config/rs6000/ibm-ldouble.c to use
    __builtin_pack_ibm128 instead of __builtin_pack_longdouble, Seghar suggested I
    allow __builtin_pack_ibm128 and __builtin_unpack_ibm128 on systems that don't
    enable __float128.  This patch maps those built-in functions and __ibm128 to
    their long double counterparts.  This way, people could use these types for
    library glue code.
    
    gcc/
    2020-11-15  Michael Meissner  <meissner@linux.ibm.com>
    
            * config/rs6000/rs6000-c.c (rs6000_cpu_cpp_builtins): If we don't
            have __float128 support enabled, but long double is IBM 128-bit,
            add defines to map __ibm128, __builtin_pack_ibm128, and
            __builtin_unpack_ibm128 into their long double counterparts.
    
    libgcc/
    2020-11-15  Michael Meissner  <meissner@linux.ibm.com>
    
            * config/rs6000/ibm-ldouble.c (IBM128_TYPE): Use __ibm128 if there
            is a define for it.
            (pack_ldouble): Use __builtin_pack_ibm128.

Diff:
---
 gcc/config/rs6000/rs6000-c.c       | 10 ++++++++++
 libgcc/config/rs6000/ibm-ldouble.c | 14 ++++++++------
 2 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/gcc/config/rs6000/rs6000-c.c b/gcc/config/rs6000/rs6000-c.c
index cc1e997524e..e42368278e6 100644
--- a/gcc/config/rs6000/rs6000-c.c
+++ b/gcc/config/rs6000/rs6000-c.c
@@ -695,6 +695,16 @@ rs6000_cpu_cpp_builtins (cpp_reader *pfile)
       builtin_define ("__builtin_huge_valq=__builtin_huge_valf128");
     }
 
+  /* If we don't support __float128, we don't create the __ibm128 type, nor do
+     we enable the pack and unpack built-in functions.  However, if long double
+     is IBM 128-bit, just map these into the long double versions.  */
+  if (!TARGET_FLOAT128_TYPE && FLOAT128_IBM_P (TFmode) && TARGET_HARD_FLOAT)
+    {
+      builtin_define ("__ibm128=long double");
+      builtin_define ("__builtin_pack_ieee128=__builtin_pack_longdouble");
+      builtin_define ("__builtin_unpack_ieee128=__builtin_unpack_longdouble");
+    }
+
   /* Tell users they can use __builtin_bswap{16,64}.  */
   builtin_define ("__HAVE_BSWAP__");
 
diff --git a/libgcc/config/rs6000/ibm-ldouble.c b/libgcc/config/rs6000/ibm-ldouble.c
index dd2a02373f2..8683efadf14 100644
--- a/libgcc/config/rs6000/ibm-ldouble.c
+++ b/libgcc/config/rs6000/ibm-ldouble.c
@@ -58,10 +58,13 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 #define nonfinite(a) unlikely (! isless (fabs (a), inf ()))
 
 /* If we have __float128/_Float128, use __ibm128 instead of long double.  On
-   other systems, use long double, because __ibm128 might not have been
-   created.  */
-#ifdef __FLOAT128__
+   other systems, we might have defined __ibm128 to map into long double, so
+   use __ibm128 in that case also.  */
+#if (defined (__FLOAT128__)						\
+     || (defined (__LONG_DOUBLE_128__) && defined (__LONG_DOUBLE_IBM128__) \
+	 && !defined (_SOFT_DOUBLE) && defined (__ibm128)))
 #define IBM128_TYPE __ibm128
+#define HAVE_IBM128 1
 #else
 #define IBM128_TYPE long double
 #endif
@@ -102,9 +105,8 @@ __asm__ (".symver __gcc_qadd,_xlqadd@GCC_3.4\n\t"
 static inline IBM128_TYPE
 pack_ldouble (double dh, double dl)
 {
-#if defined (__LONG_DOUBLE_128__) && defined (__LONG_DOUBLE_IBM128__)	\
-    && !(defined (_SOFT_FLOAT) || defined (__NO_FPRS__))
-  return __builtin_pack_longdouble (dh, dl);
+#ifdef HAVE_IBM128
+  return __builtin_pack_ibm128 (dh, dl);
 #else
   union
   {