[PATCH] [powerpc] fegetenv_and_set_rn now uses the builtins provided by GCC.

[Manjunath Matti <mmatti@linux.ibm.com>]

On powerpc, SET_RESTORE_ROUND uses inline assembly to optimize the
prologue get/save/set rounding mode operations for POWER9 and
later by using 'mffscrn' where possible, this was introduced by
commit f1c56cdff09f650ad721fae026eb6a3651631f3d.

GCC version 14 onwards supports builtins as __builtin_set_fpscr_rn
which now returns the FPSCR fields in a double. This feature is
available on Power9 when the __SET_FPSCR_RN_RETURNS_FPSCR__ macro
is defined.
GCC commit ef3bbc69d15707e4db6e2f198c621effb636cc26 adds
this feature.

Changes are done to use __builtin_set_fpscr_rn instead of mffscrn
or mffscrni in __fe_mffscrn(rn).

Suggested-by: Carl Love <cel@us.ibm.com>
---
 sysdeps/powerpc/fpu/fenv_libc.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/sysdeps/powerpc/fpu/fenv_libc.h b/sysdeps/powerpc/fpu/fenv_libc.h
index fa5e1c697e..a2a12d914b 100644
--- a/sysdeps/powerpc/fpu/fenv_libc.h
+++ b/sysdeps/powerpc/fpu/fenv_libc.h
@@ -68,6 +68,14 @@ extern const fenv_t *__fe_mask_env (void) attribute_hidden;
     __fr;								\
   })
 
+/* Starting with GCC 14 __builtin_set_fpscr_rn can be used to return the
+   FPSCR fields as a double.  This support is available
+   on Power9 when the __SET_FPSCR_RN_RETURNS_FPSCR__ macro is defined.
+   To retain backward compatibility with older GCC, we still retain the
+   old inline assembly implementation.*/
+#ifdef __SET_FPSCR_RN_RETURNS_FPSCR__
+#define __fe_mffscrn(rn)  __builtin_set_fpscr_rn (rn)
+#else
 #define __fe_mffscrn(rn)						\
   ({register fenv_union_t __fr;						\
     if (__builtin_constant_p (rn))					\
@@ -83,6 +91,7 @@ extern const fenv_t *__fe_mask_env (void) attribute_hidden;
     }									\
     __fr.fenv;								\
   })
+#endif
 
 /* Like fegetenv_control, but also sets the rounding mode.  */
 #ifdef _ARCH_PWR9
-- 
2.39.3