Message ID | 20200609213301.3591135-10-adhemerval.zanella@linaro.org |
---|---|
State | New |
Headers | show |
Series | [01/13] math: Decompose math-use-builtins.h | expand |
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 >
The 06/10/2020 17:39, Stefan Liebler via Libc-alpha wrote: > 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 in general the builtins based implementation must be compiled with -fno-math-errno if they have error conditions otherwise math-errno may cause the compiler not to do a single instruction inline like in this sqrt case. > > 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 > > > --
On 10/06/2020 12:45, Szabolcs Nagy wrote: > The 06/10/2020 17:39, Stefan Liebler via Libc-alpha wrote: >> 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 > > in general the builtins based implementation > must be compiled with -fno-math-errno if > they have error conditions otherwise math-errno > may cause the compiler not to do a single > instruction inline like in this sqrt case. Afaik libm is already build with -fno-math-errno with: Makeconfig:849:+extra-math-flags = $(if $(filter libm,$(in-module)),-fno-math-errno,-fmath-errno) And for some implementation (either default or compat ones) we have specific wrapper (for instance w_sqrt_*) to handle errno.
On 6/10/20 5:59 PM, Adhemerval Zanella via Libc-alpha wrote: > > > On 10/06/2020 12:45, Szabolcs Nagy wrote: >> The 06/10/2020 17:39, Stefan Liebler via Libc-alpha wrote: >>> 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 >> >> in general the builtins based implementation >> must be compiled with -fno-math-errno if >> they have error conditions otherwise math-errno >> may cause the compiler not to do a single >> instruction inline like in this sqrt case. > > Afaik libm is already build with -fno-math-errno with: > > Makeconfig:849:+extra-math-flags = $(if $(filter libm,$(in-module)),-fno-math-errno,-fmath-errno) > > And for some implementation (either default or compat ones) > we have specific wrapper (for instance w_sqrt_*) to handle > errno. > Hi Adhemerval, I've applied your patches and successfully run some test builds on s390x/s390. Using the builtins for sqrt and sqrtf works fine. This patch is okay. Thanks, Stefan
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