Use system default for long double if not specified on PowerPC.

Message ID Yd8YI+xecc2Ylqel@toto.the-meissners.org
State New
Headers
Series Use system default for long double if not specified on PowerPC. |

Commit Message

Michael Meissner Jan. 12, 2022, 6:04 p.m. UTC
  Use system default for long double if not specified on PowerPC.

If the user did not specify a default long double format, use the long double
default for the build compiler for the long double default.  This patch will
allow compilers built on a distribution that has changed the 128-bit floating
point format to use the default used on the system.

I did a normal normal bootstrap and make check regression on a little
endian power9 system and there were no regressions.

In addition, I built a compiler where I configured the default to use IEEE
128-bit floating point for long double.  I then used that compiler to
build a bootstrap with this patch applied and I did not set the floating
point format.  I verified that the compiler built with this patch defaults
long double to be IEEE 128-bit.

Can I apply this patch to the trunk for GCC 12?

gcc/
2022-01-12  Michael Meissner  <meissner@the-meissners.org>

	* config/rs6000/rs6000.c (TARGET_IEEEQUAD_DEFAULT): If the
	compiler used to build this compiler defaults long double to IEEE
	128-bit, then make it the default for the target.
---
 gcc/config/rs6000/rs6000.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)
  

Patch

diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index 0e3481c8327..e59f7aa49c8 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -91,14 +91,22 @@ 
      explicitly redefine TARGET_IEEEQUAD and TARGET_IEEEQUAD_DEFAULT to 0, so
      those systems will not pick up this default.  This needs to be after all
      of the include files, so that POWERPC_LINUX and POWERPC_FREEBSD are
-     properly defined.  */
+     properly defined.
+
+     If we are being built by a compiler that uses IEEE 128-bit as the default
+     long double and no explicit long double format was selected, then also
+     default long double to IEEE 128-bit.  */
 #ifndef TARGET_IEEEQUAD_DEFAULT
 #if !defined (POWERPC_LINUX) && !defined (POWERPC_FREEBSD)
 #define TARGET_IEEEQUAD_DEFAULT 1
 #else
+#ifdef __LONG_DOUBLE_IEEE128__
+#define TARGET_IEEEQUAD_DEFAULT 1
+#else
 #define TARGET_IEEEQUAD_DEFAULT 0
 #endif
 #endif
+#endif
 
 /* Don't enable PC-relative addressing if the target does not support it.  */
 #ifndef PCREL_SUPPORTED_BY_OS