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fegetenv_and_set_rn now uses the builtins provided by GCC.

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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 f1c56cdff0.

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>
Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
This commit is contained in:
Manjunath Matti 2023-09-23 10:49:51 -05:00 • committed by Adhemerval Zanella
parent 551101e824
commit 4eac1825ed
1 changed files with 9 additions and 0 deletions
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9
sysdeps/powerpc/fpu/fenv_libc.h
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@ -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