* [PATCH] PPC fenv fixes 4th update
@ 2007-05-01 22:08 Steven Munroe
2007-05-02 8:22 ` Ulrich Drepper
0 siblings, 1 reply; 3+ messages in thread
From: Steven Munroe @ 2007-05-01 22:08 UTC (permalink / raw)
To: GNU libc hacker; +Cc: Jakub Jelinek, Richard Henderson
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Updated patch responceding to comments.
[-- Attachment #2: ppc-fenv-20070425.txt --]
[-- Type: text/plain, Size: 14416 bytes --]
2007-04-30 Steven Munroe <sjmunroe@us.ibm.com>
Peter Bergner <bergner@us.ibm.com>
* sysdeps/powerpc/bits/fenv.h: Declare __fe_mask_env extern.
Define FE_NOMASK_ENV as FE_EANBLED_ENV. Define FE_MASK_ENV.
* sysdeps/powerpc/fpu/Makefile: Add fe_mask to libm-support.
* sysdeps/powerpc/fpu/fe_mask.c: New file.
* sysdeps/powerpc/fpu/fedisblxcpt.c (fedisableexcept):
Call __fe_mask_env() if all FP exceptions disabled.
* sysdeps/powerpc/fpu/feholdexcpt.c (feholdexcept): Copy high 32-bits
from old FPSCR to new fenv to propagate DFP rounding modes.
Call __fe_mask_env() if FP exceptions previously enabled.
* sysdeps/powerpc/fpu/fesetenv.c (fesetenv): Change mask to merge
exceptions from env. Use __fe_nomask_env() or __fe_mask_env() when
transitioning from all exceptions disabled to any exception enabled
or visa versa.
* sysdeps/powerpc/fpu/feupdateenv.c (__feupdateenv): Change mask to
merge exceptions from env. Call __fe_nomask_env or __fe_mask_env
when transitioning from all exceptions disabled to any exception
enabled or visa versa.
* sysdeps/unix/sysv/linux/powerpc/powerpc32/fe_mask.c: New file.
* sysdeps/unix/sysv/linux/powerpc/powerpc64/fe_mask.c: New file.
diff -urN libc25-cvstip-20070320/sysdeps/powerpc/bits/fenv.h libc25/sysdeps/powerpc/bits/fenv.h
--- libc25-cvstip-20070320/sysdeps/powerpc/bits/fenv.h 2002-10-17 17:38:37.000000000 -0500
+++ libc25/sysdeps/powerpc/bits/fenv.h 2007-04-05 15:38:33.000000000 -0500
@@ -137,9 +137,19 @@
# define FE_NONIEEE_ENV (&__fe_nonieee_env)
/* Floating-point environment with all exceptions enabled. Note that
- just evaluating this value will set the processor into 'FPU
- exceptions imprecise recoverable' mode, which may cause a significant
- performance penalty (but have no other visible effect). */
+ just evaluating this value does not change the processor exception mode.
+ Passing this mask to fesetenv will result in a prctl syscall to change
+ the MSR FE0/FE1 bits to "Precise Mode". On some processors this will
+ result in slower floating point execution. This is last until an fenv
+ or exception mask is installed that disables all FP exceptions. */
extern const fenv_t *__fe_nomask_env (void);
-# define FE_NOMASK_ENV (__fe_nomask_env ())
+# define FE_NOMASK_ENV FE_ENABLED_ENV
+
+/* Floating-point environment with all exceptions disabled. Note that
+ just evaluating this value does not change the processor exception mode.
+ Passing this mask to fesetenv will result in a prctl syscall to change
+ the MSR FE0/FE1 bits to "Ignore Exceptions Mode". On most processors
+ this allows the fastest possible floating point execution.*/
+extern const fenv_t *__fe_mask_env (void);
+# define FE_MASK_ENV FE_DFL_ENV
#endif
diff -urN libc25-cvstip-20070320/sysdeps/powerpc/fpu/Makefile libc25/sysdeps/powerpc/fpu/Makefile
--- libc25-cvstip-20070320/sysdeps/powerpc/fpu/Makefile 2004-05-25 23:33:09.000000000 -0500
+++ libc25/sysdeps/powerpc/fpu/Makefile 2007-03-27 14:49:12.000000000 -0500
@@ -1,5 +1,5 @@
ifeq ($(subdir),math)
-libm-support += fenv_const fe_nomask t_sqrt
+libm-support += fenv_const fe_nomask fe_mask t_sqrt
# libm needs ld.so to access dl_hwcap
$(objpfx)libm.so: $(elfobjdir)/ld.so
diff -urN libc25-cvstip-20070320/sysdeps/powerpc/fpu/fe_mask.c libc25/sysdeps/powerpc/fpu/fe_mask.c
--- libc25-cvstip-20070320/sysdeps/powerpc/fpu/fe_mask.c Wed Dec 31 18:00:00 1969
+++ libc25/sysdeps/powerpc/fpu/fe_mask.c Tue Mar 27 13:59:43 2007
@@ -0,0 +1,32 @@
+/* Procedure definition for FE_MASK_ENV.
+ Copyright (C) 2007 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, write to the Free
+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+ 02111-1307 USA. */
+
+#include <fenv.h>
+#include <errno.h>
+
+/* This is presently a stub, until it's decided how the kernels should
+ support this. */
+
+const fenv_t *
+__fe_mask_env(void)
+{
+ __set_errno (ENOSYS);
+ return FE_DFL_ENV;
+}
+stub_warning (__fe_mask_env)
diff -urN libc25-cvstip-20070320/sysdeps/powerpc/fpu/fedisblxcpt.c libc25/sysdeps/powerpc/fpu/fedisblxcpt.c
--- libc25-cvstip-20070320/sysdeps/powerpc/fpu/fedisblxcpt.c 2001-07-05 23:56:02.000000000 -0500
+++ libc25/sysdeps/powerpc/fpu/fedisblxcpt.c 2007-03-27 13:59:43.000000000 -0500
@@ -24,7 +24,7 @@
fedisableexcept (int excepts)
{
fenv_union_t fe;
- int result;
+ int result, new;
result = fegetexcept ();
@@ -44,7 +44,11 @@
fe.l[1] &= ~(1 << (31 - FPSCR_VE));
fesetenv_register (fe.fenv);
- if ((fegetexcept () & excepts) != 0)
+ new = fegetexcept ();
+ if (new == 0 && result != 0)
+ (void)__fe_mask_env ();
+
+ if ((new & excepts) != 0)
result = -1;
return result;
}
diff -urN libc25-cvstip-20070320/sysdeps/powerpc/fpu/feholdexcpt.c libc25/sysdeps/powerpc/fpu/feholdexcpt.c
--- libc25-cvstip-20070320/sysdeps/powerpc/fpu/feholdexcpt.c 2005-07-08 13:52:46.000000000 -0500
+++ libc25/sysdeps/powerpc/fpu/feholdexcpt.c 2007-04-16 16:59:54.000000000 -0500
@@ -22,17 +22,24 @@
int
feholdexcept (fenv_t *envp)
{
- fenv_union_t u;
+ fenv_union_t old, new;
- /* Get the current state. */
- u.fenv = *envp = fegetenv_register ();
+ /* Save the currently set exceptions. */
+ old.fenv = *envp = fegetenv_register ();
- /* Clear everything except for the rounding mode and non-IEEE arithmetic
+ /* Clear everything except for the rounding modes and non-IEEE arithmetic
flag. */
- u.l[1] = u.l[1] & 7;
+ new.l[1] = old.l[1] & 7;
+ new.l[0] = old.l[0];
+
+ /* If the old env had any eabled exceptions, then mask SIGFPE in the
+ MSR FE0/FE1 bits. This may allow the FPU to run faster because it
+ always takes the default action and can not generate SIGFPE. */
+ if ((old.l[1] & 0x000000F8) != 0)
+ (void)__fe_mask_env ();
/* Put the new state in effect. */
- fesetenv_register (u.fenv);
+ fesetenv_register (new.fenv);
return 0;
}
diff -urN libc25-cvstip-20070320/sysdeps/powerpc/fpu/fesetenv.c libc25/sysdeps/powerpc/fpu/fesetenv.c
--- libc25-cvstip-20070320/sysdeps/powerpc/fpu/fesetenv.c 2002-09-09 20:26:37.000000000 -0500
+++ libc25/sysdeps/powerpc/fpu/fesetenv.c 2007-04-16 17:00:34.000000000 -0500
@@ -1,5 +1,5 @@
/* Install given floating-point environment.
- Copyright (C) 1997,99,2000,01,02 Free Software Foundation, Inc.
+ Copyright (C) 1997,99,2000,01,02,07 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
@@ -23,6 +23,26 @@
int
__fesetenv (const fenv_t *envp)
{
+ fenv_union_t old, new;
+
+ /* get the currently set exceptions. */
+ new.fenv = *envp;
+ old.fenv = fegetenv_register ();
+
+ /* If the old env has no eabled exceptions and the new env has any enabled
+ exceptions, then unmask SIGFPE in the MSR FE0/FE1 bits. This will put
+ the hardware into "precise mode" and may cause the FPU to run slower on
+ some hardware. */
+ if ((old.l[1] & 0x000000F8) == 0 && (new.l[1] & 0x000000F8) != 0)
+ (void)__fe_nomask_env ();
+
+ /* If the old env had any eabled exceptions and the new env has no enabled
+ exceptions, then mask SIGFPE in the MSR FE0/FE1 bits. This may allow the
+ FPU to run faster because it always takes the default action and can not
+ generate SIGFPE. */
+ if ((old.l[1] & 0x000000F8) != 0 && (new.l[1] & 0x000000F8) == 0)
+ (void)__fe_mask_env ();
+
fesetenv_register (*envp);
/* Success. */
diff -urN libc25-cvstip-20070320/sysdeps/powerpc/fpu/feupdateenv.c libc25/sysdeps/powerpc/fpu/feupdateenv.c
--- libc25-cvstip-20070320/sysdeps/powerpc/fpu/feupdateenv.c 2001-07-05 23:56:02.000000000 -0500
+++ libc25/sysdeps/powerpc/fpu/feupdateenv.c 2007-04-16 17:01:00.000000000 -0500
@@ -1,5 +1,5 @@
/* Install given floating-point environment and raise exceptions.
- Copyright (C) 1997,99,2000,01 Free Software Foundation, Inc.
+ Copyright (C) 1997,99,2000,01,07 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
@@ -30,8 +30,24 @@
new.fenv = *envp;
old.fenv = fegetenv_register ();
- /* Copy the set exceptions from `old' to `new'. */
- new.l[1] = (new.l[1] & 0xE00000FF) | (old.l[1] & 0x1FFFFF00);
+ /* Restore rounding mode and exception enable from *envp and merge
+ exceptions. Leave fraction rounded/inexact and FP result/CC bits
+ unchanged. */
+ new.l[1] = (old.l[1] & 0x1FFFFF00) | (new.l[1] & 0x1FF80FFF);
+
+ /* If the old env has no eabled exceptions and the new env has any enabled
+ exceptions, then unmask SIGFPE in the MSR FE0/FE1 bits. This will put
+ the hardware into "precise mode" and may cause the FPU to run slower on
+ some hardware. */
+ if ((old.l[1] & 0x000000F8) == 0 && (new.l[1] & 0x000000F8) != 0)
+ (void)__fe_nomask_env ();
+
+ /* If the old env had any eabled exceptions and the new env has no enabled
+ exceptions, then mask SIGFPE in the MSR FE0/FE1 bits. This may allow the
+ FPU to run faster because it always takes the default action and can not
+ generate SIGFPE. */
+ if ((old.l[1] & 0x000000F8) != 0 && (new.l[1] & 0x000000F8) == 0)
+ (void)__fe_mask_env ();
/* Atomically enable and raise (if appropriate) exceptions set in `new'. */
fesetenv_register (new.fenv);
diff -urN libc25-cvstip-20070320/sysdeps/unix/sysv/linux/powerpc/powerpc32/fe_mask.c libc25/sysdeps/unix/sysv/linux/powerpc/powerpc32/fe_mask.c
--- libc25-cvstip-20070320/sysdeps/unix/sysv/linux/powerpc/powerpc32/fe_mask.c Wed Dec 31 18:00:00 1969
+++ libc25/sysdeps/unix/sysv/linux/powerpc/powerpc32/fe_mask.c Tue Mar 27 13:59:43 2007
@@ -0,0 +1,68 @@
+/* Procedure definition for FE_MASK_ENV for Linux/ppc.
+ Copyright (C) 2007 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, write to the Free
+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+ 02111-1307 USA. */
+
+#include <fenv.h>
+#include <errno.h>
+#include <signal.h>
+#include <unistd.h>
+#include <sysdep.h>
+#include <sys/prctl.h>
+#include <kernel-features.h>
+
+#if __ASSUME_NEW_PRCTL_SYSCALL == 0
+/* This is rather fiddly under Linux. We don't have direct access,
+ and there is no system call, but we can change the bits
+ in a signal handler's context... */
+
+static struct sigaction oact;
+
+static void
+fe_mask_handler (int signum, struct sigcontext *sc)
+{
+ sc->regs->msr &= ~0x900ul; /* FE0 | FE1 */
+ sigaction (SIGUSR1, &oact, NULL);
+}
+#endif
+
+const fenv_t *
+__fe_mask_env (void)
+{
+#if __ASSUME_NEW_PRCTL_SYSCALL == 0
+# if defined PR_SET_FPEXC && defined PR_FP_EXC_DISABLED
+ int result = INLINE_SYSCALL (prctl, 2, PR_SET_FPEXC, PR_FP_EXC_DISABLED);
+
+ if (result == -1 && errno == EINVAL)
+# endif
+ {
+ struct sigaction act;
+
+ act.sa_handler = (sighandler_t) fe_mask_handler;
+ sigemptyset (&act.sa_mask);
+ act.sa_flags = 0;
+
+ sigaction (SIGUSR1, &act, &oact);
+ raise (SIGUSR1);
+ }
+#else
+ INTERNAL_SYSCALL_DECL (err);
+ INTERNAL_SYSCALL (prctl, err, 2, PR_SET_FPEXC, PR_FP_EXC_DISABLED);
+#endif
+
+ return FE_DFL_ENV;
+}
diff -urN libc25-cvstip-20070320/sysdeps/unix/sysv/linux/powerpc/powerpc64/fe_mask.c libc25/sysdeps/unix/sysv/linux/powerpc/powerpc64/fe_mask.c
--- libc25-cvstip-20070320/sysdeps/unix/sysv/linux/powerpc/powerpc64/fe_mask.c Wed Dec 31 18:00:00 1969
+++ libc25/sysdeps/unix/sysv/linux/powerpc/powerpc64/fe_mask.c Tue Mar 27 13:59:43 2007
@@ -0,0 +1,43 @@
+/* Procedure definition for FE_MASK_ENV for Linux/ppc64.
+ Copyright (C) 2007 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, write to the Free
+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+ 02111-1307 USA. */
+
+#include <fenv.h>
+#include <errno.h>
+#include <sysdep.h>
+#include <sys/syscall.h>
+#include <sys/prctl.h>
+#include <kernel-features.h>
+
+const fenv_t *
+__fe_mask_env (void)
+{
+#if defined PR_SET_FPEXC && defined PR_FP_EXC_DISABLED
+ int result;
+ INTERNAL_SYSCALL_DECL (err);
+ result = INTERNAL_SYSCALL (prctl, err, 2, PR_SET_FPEXC, PR_FP_EXC_DISABLED);
+# ifndef __ASSUME_NEW_PRCTL_SYSCALL
+ if (INTERNAL_SYSCALL_ERROR_P (result, err)
+ && INTERNAL_SYSCALL_ERRNO (result, err) == EINVAL)
+ __set_errno (ENOSYS);
+# endif
+#else
+ __set_errno (ENOSYS);
+#endif
+ return FE_DFL_ENV;
+}
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] PPC fenv fixes 4th update
2007-05-01 22:08 [PATCH] PPC fenv fixes 4th update Steven Munroe
@ 2007-05-02 8:22 ` Ulrich Drepper
2007-05-02 14:06 ` Steven Munroe
0 siblings, 1 reply; 3+ messages in thread
From: Ulrich Drepper @ 2007-05-02 8:22 UTC (permalink / raw)
To: Steven Munroe; +Cc: GNU libc hacker, Jakub Jelinek, Richard Henderson
[-- Attachment #1: Type: text/plain, Size: 478 bytes --]
Steven Munroe wrote:
> +/* This is presently a stub, until it's decided how the kernels should
> + support this. */
> +
> +const fenv_t *
> +__fe_mask_env(void)
> +{
> + __set_errno (ENOSYS);
> + return FE_DFL_ENV;
> +}
Why are you sending a patch if it's incomplete? Fix the kernel and then
send a patch. Who knows, maybe a completely different solution is needed.
--
➧ Ulrich Drepper ➧ Red Hat, Inc. ➧ 444 Castro St ➧ Mountain View, CA ❖
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] PPC fenv fixes 4th update
2007-05-02 8:22 ` Ulrich Drepper
@ 2007-05-02 14:06 ` Steven Munroe
0 siblings, 0 replies; 3+ messages in thread
From: Steven Munroe @ 2007-05-02 14:06 UTC (permalink / raw)
To: Ulrich Drepper; +Cc: GNU libc hacker, Jakub Jelinek, Richard Henderson
Ulrich Drepper wrote:
> Steven Munroe wrote:
>
>> +/* This is presently a stub, until it's decided how the kernels should
>> + support this. */
>> +
>> +const fenv_t *
>> +__fe_mask_env(void)
>> +{
>> + __set_errno (ENOSYS);
>> + return FE_DFL_ENV;
>> +}
>>
>
> Why are you sending a patch if it's incomplete? Fix the kernel and then
> send a patch. Who knows, maybe a completely different solution is needed.
>
>
The only problem is the comment which should say:
/* This is a generic stub. An OS specific override is required to clear
the FE0/FE1 bits in the MSR. MSR update is privileged, so this will
normally involve a syscall. */
The real implementations for linux are in
sysdeps/unix/sysv/linux/powerpc/powerpc[32|64]/fe_mask.c
hhhmm should not this be?:
sysdeps/unix/sysv/linux/powerpc/powerpc[32|64]/fpu/fe_mask.c
History bites. Dr. Bergner just copied the existing fe_nomask.c stubs
and overrides. I'll fix it and resubmit.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2007-05-01 22:08 [PATCH] PPC fenv fixes 4th update Steven Munroe
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2007-05-02 14:06 ` Steven Munroe
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