Patchwork [libatomic] : Add config/x86/fenv.c

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Submitter Uros Bizjak
Date Nov. 8, 2013, 5:19 p.m.
Message ID <CAFULd4YHmNe8mN=QPA_1Y3y8-dO0vmY+YBwaZsStOCf2hFCL8g@mail.gmail.com>
Download mbox | patch
Permalink /patch/289895/
State New
Headers show

Comments

Uros Bizjak - Nov. 8, 2013, 5:19 p.m.
On Fri, Nov 8, 2013 at 2:13 PM, Joseph S. Myers <joseph@codesourcery.com> wrote:

>> Can we introduce a target-dependant source here, in the same way as
>
> Sure, that seems a reasonable thing to do.  I think putting a file fenv.c
> in an appropriate subdirectory of libatomic/config will result in it being
> found automatically by the existing search path logic, but you'll need to
> test that.

Attached is the x86 optimized implementation of fenv.c. The source
depends as little as possible on fenv.h definitions - these are
defined by hardware, and for sure won't change soon in
hardware-dependant file.

2013-11-08  Uros Bizjak  <ubizjak@gmail.com>

    * config/x86/fenv.c: New file.

Bootstrapped and regression tested on x86_64-pc-linux-gnu {,-m32}. The
testing of atomics currently fails on 32bit target due to missing
__atomic_{load,store}_16 functions, so the patch is not adequately
tested yet.

Yes, I have tested that the libatomic's auto-configuration logic works ;)

Uros.
Joseph S. Myers - Nov. 8, 2013, 9:32 p.m.
On Fri, 8 Nov 2013, Uros Bizjak wrote:

> On Fri, Nov 8, 2013 at 2:13 PM, Joseph S. Myers <joseph@codesourcery.com> wrote:
> 
> >> Can we introduce a target-dependant source here, in the same way as
> >
> > Sure, that seems a reasonable thing to do.  I think putting a file fenv.c
> > in an appropriate subdirectory of libatomic/config will result in it being
> > found automatically by the existing search path logic, but you'll need to
> > test that.
> 
> Attached is the x86 optimized implementation of fenv.c. The source
> depends as little as possible on fenv.h definitions - these are
> defined by hardware, and for sure won't change soon in
> hardware-dependant file.

This is fine with me.

> Bootstrapped and regression tested on x86_64-pc-linux-gnu {,-m32}. The
> testing of atomics currently fails on 32bit target due to missing
> __atomic_{load,store}_16 functions, so the patch is not adequately
> tested yet.

(See <http://gcc.gnu.org/ml/gcc-patches/2013-11/msg00894.html> for 
commentary on that issue and what might be the right approach for a fix.)

Patch

Index: ChangeLog
===================================================================
--- ChangeLog	(revision 204574)
+++ ChangeLog	(working copy)
@@ -1,3 +1,7 @@ 
+2013-11-08  Uros Bizjak  <ubizjak@gmail.com>
+
+	* config/x86/fenv.c: New file.
+
 2013-11-07  Joseph Myers  <joseph@codesourcery.com>
 
 	* fenv.c: New file.
Index: config/x86/fenv.c
===================================================================
--- config/x86/fenv.c	(revision 0)
+++ config/x86/fenv.c	(working copy)
@@ -0,0 +1,115 @@ 
+/* Copyright (C) 2013 Free Software Foundation, Inc.
+
+   This file is part of the GNU Atomic Library (libatomic).
+
+   Libatomic is free software; you can redistribute it and/or modify it
+   under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   Libatomic 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 General Public License for
+   more details.
+
+   Under Section 7 of GPL version 3, you are granted additional
+   permissions described in the GCC Runtime Library Exception, version
+   3.1, as published by the Free Software Foundation.
+
+   You should have received a copy of the GNU General Public License and
+   a copy of the GCC Runtime Library Exception along with this program;
+   see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include "libatomic_i.h"
+
+#ifdef HAVE_FENV_H
+# include <fenv.h>
+#endif
+
+struct fenv
+{
+  unsigned short int __control_word;
+  unsigned short int __unused1;
+  unsigned short int __status_word;
+  unsigned short int __unused2;
+  unsigned short int __tags;
+  unsigned short int __unused3;
+  unsigned int __eip;
+  unsigned short int __cs_selector;
+  unsigned int __opcode:11;
+  unsigned int __unused4:5;
+  unsigned int __data_offset;
+  unsigned short int __data_selector;
+  unsigned short int __unused5;
+};
+
+/* Raise the supported floating-point exceptions from EXCEPTS.  Other
+   bits in EXCEPTS are ignored.  */
+
+void
+__atomic_feraiseexcept (int excepts __attribute__ ((unused)))
+{
+#ifdef FE_INVALID
+  if (excepts & FE_INVALID)
+    {
+      float f = 0.0f;
+#ifdef __x86_64__
+      volatile float r __attribute__ ((unused));
+      asm volatile ("%vdivss\t{%0, %d0|%d0, %0}" : "+x" (f));
+      r = f; /* Needed to trigger exception.   */
+#else
+      asm volatile ("fdiv\t{%y0, %0|%0, %y0}" : "+t" (f));
+      /* No need for fwait, exception is triggered by emitted fstp.  */
+#endif
+    }
+#endif
+#ifdef FE_DIVBYZERO
+  if (excepts & FE_DIVBYZERO)
+    {
+      float f = 1.0f, g = 0.0f;
+#ifdef __x86_64__
+      volatile float r __attribute__ ((unused));
+      asm volatile ("%vdivss\t{%1, %d0|%d0, %1}" : "+x" (f) : "xm" (g));
+      r = f; /* Needed to trigger exception.   */
+#else
+      asm volatile ("fdivs\t%1" : "+t" (f) : "m" (g));
+      /* No need for fwait, exception is triggered by emitted fstp.  */
+#endif
+    }
+#endif
+#ifdef FE_OVERFLOW
+  if (excepts & FE_OVERFLOW)
+    {
+      struct fenv temp;
+      asm volatile ("fnstenv\t%0" : "=m" (temp));
+      temp.__status_word |= 0x08;
+      asm volatile ("fldenv\t%0" : : "m" (temp));
+      asm volatile ("fwait");
+    }
+#endif
+#ifdef FE_UNDERFLOW
+  if (excepts & FE_UNDERFLOW)
+    {
+      struct fenv temp;
+      asm volatile ("fnstenv\t%0" : "=m" (temp));
+      temp.__status_word |= 0x10;
+      asm volatile ("fldenv\t%0" : : "m" (temp));
+      asm volatile ("fwait");
+    }
+#endif
+#ifdef FE_INEXACT
+  if (excepts & FE_INEXACT)
+    {
+      float f = 1.0f, g = 3.0f;
+#ifdef __x86_64__
+      volatile float r __attribute__ ((unused));
+      asm volatile ("%vdivss\t{%1, %d0|%d0, %1}" : "+x" (f) : "xm" (g));
+      r = f; /* Needed to trigger exception.   */
+#else
+      asm volatile ("fdivs\t%1" : "+t" (f) : "m" (g));
+      /* No need for fwait, exception is triggered by emitted fstp.  */
+#endif
+    }
+#endif
+}