[PATCH] LoongArch: Add math-barriers.h

[Adhemerval Zanella Netto]

On 14/02/23 05:57, Xi Ruoyao via Libc-alpha wrote:
> This patch implements the LoongArch specific math barriers in order to omit
> the store and load from stack if possible.

LGTM, I have not see any regression with qemu.  As a side note, math/test-fenv
shows a failure so you might take a look, you might need to update ULPs as well.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

> 
> Signed-off-by: Xi Ruoyao <xry111@xry111.site>

We do not use signed-off-by, so no need to add it.

> ---
>  sysdeps/loongarch/fpu/math-barriers.h | 28 +++++++++++++++++++++++++++
>  1 file changed, 28 insertions(+)
>  create mode 100644 sysdeps/loongarch/fpu/math-barriers.h
> 
> diff --git a/sysdeps/loongarch/fpu/math-barriers.h b/sysdeps/loongarch/fpu/math-barriers.h
> new file mode 100644
> index 0000000000..3e977e43a6
> --- /dev/null
> +++ b/sysdeps/loongarch/fpu/math-barriers.h
> @@ -0,0 +1,28 @@
> +/* Control when floating-point expressions are evaluated.  LoongArch version.
> +   Copyright (C) 2023 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#ifndef _LOONGARCH_MATH_BARRIERS_H
> +#define _LOONGARCH_MATH_BARRIERS_H 1
> +
> +/* Generic code forces values to memory; we don't need to do that.  */
> +#define math_opt_barrier(x)					\
> +  ({ __typeof (x) __x = (x); __asm ("" : "+frm" (__x)); __x; })
> +#define math_force_eval(x)						\
> +  ({ __typeof (x) __x = (x); __asm __volatile__ ("" : : "frm" (__x)); })
> +
> +#endif /* math-barriers.h */