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

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Submitter Uros Bizjak
Date Nov. 10, 2013, 11:49 a.m.
Message ID <CAFULd4aG+qO88BCrUcBdLQ71N-gfzWrngzfm5p0PzkWMeDmV1g@mail.gmail.com>
Download mbox | patch
Permalink /patch/290040/
State New
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Comments

Uros Bizjak - Nov. 10, 2013, 11:49 a.m.
On Fri, Nov 8, 2013 at 10:32 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.)

Thanks, this worked for me.

Attached is the x86 specific fenv.c. The source does not depend on
fenv.h anymore and also handles denormal exception.

2013-11-10  Uros Bizjak  <ubizjak@gmail.com>

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

The patch was tested on x86_64-linux-gnu {,-m32} and committed to mainline SVN.

Uros.

Patch

Index: ChangeLog
===================================================================
--- ChangeLog	(revision 204623)
+++ 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 +1,116 @@ 
+/* 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"
+
+#define FE_INVALID	0x01
+#define FE_DENORM	0x02
+#define FE_DIVBYZERO	0x04
+#define FE_OVERFLOW	0x08
+#define FE_UNDERFLOW	0x10
+#define FE_INEXACT	0x20
+
+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)
+{
+  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
+    }
+  if (excepts & FE_DENORM)
+    {
+      struct fenv temp;
+      asm volatile ("fnstenv\t%0" : "=m" (temp));
+      temp.__status_word |= FE_DENORM;
+      asm volatile ("fldenv\t%0" : : "m" (temp));
+      asm volatile ("fwait");
+    }
+  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
+    }
+  if (excepts & FE_OVERFLOW)
+    {
+      struct fenv temp;
+      asm volatile ("fnstenv\t%0" : "=m" (temp));
+      temp.__status_word |= FE_OVERFLOW;
+      asm volatile ("fldenv\t%0" : : "m" (temp));
+      asm volatile ("fwait");
+    }
+  if (excepts & FE_UNDERFLOW)
+    {
+      struct fenv temp;
+      asm volatile ("fnstenv\t%0" : "=m" (temp));
+      temp.__status_word |= FE_UNDERFLOW;
+      asm volatile ("fldenv\t%0" : : "m" (temp));
+      asm volatile ("fwait");
+    }
+  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
+    }
+}