This separates the 32-bit sysv/linux/bsd code from the 64-bit linux

code, and makes it possible to link code compiled with different
options to those used to compile libffi.  For example, a
-mlong-double-128 libffi can be used with -mlong-double-64 code.

Using the return value area as a place to pass parameters wasn't such
a good idea, causing a failure of cls_ulonglong.c.  I didn't see this
when running the mainline gcc libffi testsuite because that version of
the test is inferior to the upstreamm libffi test.

Using NUM_FPR_ARG_REGISTERS rather than NUM_FPR_ARG_REGISTERS64 meant
that a parameter save area could be allocated before it was strictly
necessary.  Wrong but harmless.  Found when splitting apart ffi.c
into 32-bit and 64-bit support.

src/powerpc/ffitarget.h

@@ -60,45 +60,76 @@ typedef signed long            ffi_sarg;
 typedef enum ffi_abi {
   FFI_FIRST_ABI = 0,
 
-#ifdef POWERPC
-  FFI_SYSV,
-  FFI_GCC_SYSV,
-  FFI_LINUX64,
-  FFI_LINUX,
-  FFI_LINUX_SOFT_FLOAT,
-# if defined(POWERPC64)
-  FFI_DEFAULT_ABI = FFI_LINUX64,
-# elif defined(__NO_FPRS__)
-  FFI_DEFAULT_ABI = FFI_LINUX_SOFT_FLOAT,
-# elif (__LDBL_MANT_DIG__ == 106)
-  FFI_DEFAULT_ABI = FFI_LINUX,
-# else
-  FFI_DEFAULT_ABI = FFI_GCC_SYSV,
-# endif
-#endif
-
-#ifdef POWERPC_AIX
+#if defined (POWERPC_AIX)
   FFI_AIX,
   FFI_DARWIN,
   FFI_DEFAULT_ABI = FFI_AIX,
-#endif
+  FFI_LAST_ABI
 
-#ifdef POWERPC_DARWIN
+#elif defined (POWERPC_DARWIN)
   FFI_AIX,
   FFI_DARWIN,
   FFI_DEFAULT_ABI = FFI_DARWIN,
-#endif
-
-#ifdef POWERPC_FREEBSD
-  FFI_SYSV,
-  FFI_GCC_SYSV,
-  FFI_LINUX64,
-  FFI_LINUX,
-  FFI_LINUX_SOFT_FLOAT,
-  FFI_DEFAULT_ABI = FFI_SYSV,
-#endif
-
   FFI_LAST_ABI
+
+#else
+  /* The FFI_COMPAT values are used by old code.  Since libffi may be
+     a shared library we have to support old values for backwards
+     compatibility.  */
+  FFI_COMPAT_SYSV,
+  FFI_COMPAT_GCC_SYSV,
+  FFI_COMPAT_LINUX64,
+  FFI_COMPAT_LINUX,
+  FFI_COMPAT_LINUX_SOFT_FLOAT,
+
+# if defined (POWERPC64)
+  /* This bit, always set in new code, must not be set in any of the
+     old FFI_COMPAT values that might be used for 64-bit linux.  We
+     only need worry about FFI_COMPAT_LINUX64, but to be safe avoid
+     all old values.  */
+  FFI_LINUX = 8,
+  /* This and following bits can reuse FFI_COMPAT values.  */
+  FFI_LINUX_STRUCT_ALIGN = 1,
+  FFI_LINUX_LONG_DOUBLE_128 = 2,
+  FFI_DEFAULT_ABI = (FFI_LINUX
+#  ifdef __STRUCT_PARM_ALIGN__
+		     | FFI_LINUX_STRUCT_ALIGN
+#  endif
+#  ifdef __LONG_DOUBLE_128__
+		     | FFI_LINUX_LONG_DOUBLE_128
+#  endif
+		     ),
+  FFI_LAST_ABI = 12
+
+# else
+  /* This bit, always set in new code, must not be set in any of the
+     old FFI_COMPAT values that might be used for 32-bit linux/sysv/bsd.  */
+  FFI_SYSV = 8,
+  /* This and following bits can reuse FFI_COMPAT values.  */
+  FFI_SYSV_SOFT_FLOAT = 1,
+  FFI_SYSV_STRUCT_RET = 2,
+  FFI_SYSV_IBM_LONG_DOUBLE = 4,
+  FFI_SYSV_LONG_DOUBLE_128 = 16,
+
+  FFI_DEFAULT_ABI = (FFI_SYSV
+#  ifdef __NO_FPRS__
+		     | FFI_SYSV_SOFT_FLOAT
+#  endif
+#  if (defined (__SVR4_STRUCT_RETURN)					\
+       || defined (POWERPC_FREEBSD) && !defined (__AIX_STRUCT_RETURN))
+		     | FFI_SYSV_STRUCT_RET
+#  endif
+#  if __LDBL_MANT_DIG__ == 106
+		     | FFI_SYSV_IBM_LONG_DOUBLE
+#  endif
+#  ifdef __LONG_DOUBLE_128__
+		     | FFI_SYSV_LONG_DOUBLE_128
+#  endif
+		     ),
+  FFI_LAST_ABI = 32
+# endif
+#endif
+
 } ffi_abi;
 #endif
 
@@ -117,9 +148,7 @@ typedef enum ffi_abi {
 /* Needed for soft-float long-double-128 support.  */
 #define FFI_TYPE_UINT128 (FFI_TYPE_LAST + 1)
 
-/* Needed for FFI_SYSV small structure returns.
-   We use two flag bits, (FLAG_SYSV_SMST_R3, FLAG_SYSV_SMST_R4) which are
-   defined in ffi.c, to determine the exact return type and its size.  */
+/* Needed for FFI_SYSV small structure returns.  */
 #define FFI_SYSV_TYPE_SMALL_STRUCT (FFI_TYPE_LAST + 2)
 
 /* Used by ELFv2 for homogenous structure returns.  */