From: Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>
To: Manjunath Matti <mmatti@linux.ibm.com>, libc-alpha@sourceware.org
Cc: rajis@linux.ibm.com, Carl Love <cel@us.ibm.com>
Subject: Re: [PATCH] [powerpc] fegetenv_and_set_rn now uses the builtins provided by GCC.
Date: Wed, 27 Sep 2023 13:56:47 -0300 [thread overview]
Message-ID: <e32b309e-4893-4a58-9ef3-3b2dd185c1ae@linaro.org> (raw)
In-Reply-To: <20230923154951.3783611-1-mmatti@linux.ibm.com>
On 23/09/23 12:49, Manjunath Matti wrote:
> 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>
LGTM, thanks.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
> ---
> 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
next prev parent reply other threads:[~2023-09-27 16:56 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-23 15:49 Manjunath Matti
2023-09-27 16:56 ` Adhemerval Zanella Netto [this message]
2023-10-19 1:47 ` Peter Bergner
-- strict thread matches above, loose matches on Subject: below --
2023-09-12 8:27 Manjunath Matti
2023-09-12 13:27 ` Adhemerval Zanella Netto
2023-09-20 11:28 ` Manjunath S Matti
2023-09-20 13:33 ` Adhemerval Zanella Netto
2023-10-19 1:25 ` Peter Bergner
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