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PATCH: Update sysdeps/x86_64/fpu_control.h
- From: "H.J. Lu" <hongjiu dot lu at intel dot com>
- To: GNU C Library <libc-alpha at sourceware dot org>
- Date: Sun, 17 Jun 2012 12:26:02 -0700
- Subject: PATCH: Update sysdeps/x86_64/fpu_control.h
- Reply-to: "H.J. Lu" <hjl dot tools at gmail dot com>
Hi,
I missed sysdeps/x86_64/fpu_control.h and sysdeps/i386/fpu_control.h.
This patch updates sysdeps/x86_64/fpu_control.h to add __volatile__
on _FPU_GETCW and _FPU_SETCW to match sysdeps/i386/fpu_control.h. OK
to install?
The next patch will move sysdeps/x86_64/fpu_control.h to sysdeps/x86 and
remove sysdeps/i386/fpu_control.h.
Thanks.
H.J.
---
diff --git a/ChangeLog b/ChangeLog
index 3b7f988..78493aa 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2012-06-17 H.J. Lu <hongjiu.lu@intel.com>
+
+ [BZ #14117]
+ * sysdeps/x86_64/fpu_control.h (_FPU_GETCW): Add __volatile__.
+ (_FPU_SETCW): Likewise.
+
2012-06-15 H.J. Lu <hongjiu.lu@intel.com>
[BZ #14117]
diff --git a/sysdeps/x86_64/fpu_control.h b/sysdeps/x86_64/fpu_control.h
index 61bc30e..cbc47f3 100644
--- a/sysdeps/x86_64/fpu_control.h
+++ b/sysdeps/x86_64/fpu_control.h
@@ -1,5 +1,5 @@
-/* FPU control word bits. x86-64 version.
- Copyright (C) 1993,1995,1996,1997,1998,2000,2001,2002 Free Software Foundation, Inc.
+/* FPU control word bits. x86 version.
+ Copyright (C) 1993-2012 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Olaf Flebbe.
@@ -90,9 +90,13 @@
/* Type of the control word. */
typedef unsigned int fpu_control_t __attribute__ ((__mode__ (__HI__)));
-/* Macros for accessing the hardware control word. */
-#define _FPU_GETCW(cw) __asm__ ("fnstcw %0" : "=m" (*&cw))
-#define _FPU_SETCW(cw) __asm__ ("fldcw %0" : : "m" (*&cw))
+/* Macros for accessing the hardware control word.
+
+ Note that the use of these macros is no sufficient anymore with
+ recent hardware. Some floating point operations are executed in
+ the SSE/SSE2 engines which have their own control and status register. */
+#define _FPU_GETCW(cw) __asm__ __volatile__ ("fnstcw %0" : "=m" (*&cw))
+#define _FPU_SETCW(cw) __asm__ __volatile__ ("fldcw %0" : : "m" (*&cw))
/* Default control word set at startup. */
extern fpu_control_t __fpu_control;