[PATCH 10/13] s390: Use sqrt{f} builtin
Stefan Liebler
stli@linux.ibm.com
Wed Jun 10 15:39:40 GMT 2020
Hi Adhemerval,
my last tests with the sqrt builtin on s390x showed that gcc emits a
call to libm which would lead to an infinite loop:
if (x < 0)
sqrt(x)
else
sqdbr-instruction
Can you have a look into the generated code?
I will also apply your series and perform some test-runs. (next week as
I'll be on vacation the next days)
Then I'll also have a look at the fma-builtins. But those should be fine
for float and double.
Bye.
Stefan
On 6/9/20 11:32 PM, Adhemerval Zanella via Libc-alpha wrote:
> Checked on s390x-linux-gnu.
> ---
> sysdeps/s390/fpu/e_sqrt.c | 30 -----------------------
> sysdeps/s390/fpu/e_sqrtf.c | 30 -----------------------
> sysdeps/s390/fpu/math-use-builtins-sqrt.h | 4 +++
> 3 files changed, 4 insertions(+), 60 deletions(-)
> delete mode 100644 sysdeps/s390/fpu/e_sqrt.c
> delete mode 100644 sysdeps/s390/fpu/e_sqrtf.c
> create mode 100644 sysdeps/s390/fpu/math-use-builtins-sqrt.h
>
> diff --git a/sysdeps/s390/fpu/e_sqrt.c b/sysdeps/s390/fpu/e_sqrt.c
> deleted file mode 100644
> index 484c6aae95..0000000000
> --- a/sysdeps/s390/fpu/e_sqrt.c
> +++ /dev/null
> @@ -1,30 +0,0 @@
> -/* Copyright (C) 2004-2020 Free Software Foundation, Inc.
> - Contributed by Martin Schwidefsky <schwidefsky@de.ibm.com>.
> - 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/>. */
> -
> -#include <math_private.h>
> -#include <libm-alias-finite.h>
> -
> -double
> -__ieee754_sqrt (double x)
> -{
> - double res;
> -
> - __asm__ ( "sqdbr %0,%1" : "=f" (res) : "f" (x) );
> - return res;
> -}
> -libm_alias_finite (__ieee754_sqrt, __sqrt)
> diff --git a/sysdeps/s390/fpu/e_sqrtf.c b/sysdeps/s390/fpu/e_sqrtf.c
> deleted file mode 100644
> index bce49c90f1..0000000000
> --- a/sysdeps/s390/fpu/e_sqrtf.c
> +++ /dev/null
> @@ -1,30 +0,0 @@
> -/* Copyright (C) 2004-2020 Free Software Foundation, Inc.
> - Contributed by Martin Schwidefsky <schwidefsky@de.ibm.com>.
> - 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/>. */
> -
> -#include <math_private.h>
> -#include <libm-alias-finite.h>
> -
> -float
> -__ieee754_sqrtf (float x)
> -{
> - float res;
> -
> - __asm__ ( "sqebr %0,%1" : "=f" (res) : "f" (x) );
> - return res;
> -}
> -libm_alias_finite (__ieee754_sqrtf, __sqrtf)
> diff --git a/sysdeps/s390/fpu/math-use-builtins-sqrt.h b/sysdeps/s390/fpu/math-use-builtins-sqrt.h
> new file mode 100644
> index 0000000000..e94c915ba6
> --- /dev/null
> +++ b/sysdeps/s390/fpu/math-use-builtins-sqrt.h
> @@ -0,0 +1,4 @@
> +#define USE_SQRT_BUILTIN 1
> +#define USE_SQRTF_BUILTIN 1
> +#define USE_SQRTL_BUILTIN 0
> +#define USE_SQRTF128_BUILTIN 0
>
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