Title: [98029] trunk/Source/WebCore
- Revision
- 98029
- Author
- commit-qu...@webkit.org
- Date
- 2011-10-20 15:39:00 -0700 (Thu, 20 Oct 2011)
Log Message
Implement SSE denormal disabler for windows.
https://bugs.webkit.org/show_bug.cgi?id=70517
Patch by Raymond Toy <r...@google.com> on 2011-10-20
Reviewed by Kenneth Russell.
* platform/audio/DenormalDisabler.h:
(WebCore::DenormalDisabler::DenormalDisabler):
Add implementation for Windows.
(WebCore::DenormalDisabler::~DenormalDisabler):
Ditto.
(WebCore::DenormalDisabler::flushDenormalFloatToZero):
Unify Windows with mac/linux.
(WebCore::DenormalDisabler::getCSR):
Define only if we're not on Windows.
(WebCore::DenormalDisabler::setCSR):
Ditto.
Modified Paths
Diff
Modified: trunk/Source/WebCore/ChangeLog (98028 => 98029)
--- trunk/Source/WebCore/ChangeLog 2011-10-20 22:32:19 UTC (rev 98028)
+++ trunk/Source/WebCore/ChangeLog 2011-10-20 22:39:00 UTC (rev 98029)
@@ -1,3 +1,23 @@
+2011-10-20 Raymond Toy <r...@google.com>
+
+ Implement SSE denormal disabler for windows.
+
+ https://bugs.webkit.org/show_bug.cgi?id=70517
+
+ Reviewed by Kenneth Russell.
+
+ * platform/audio/DenormalDisabler.h:
+ (WebCore::DenormalDisabler::DenormalDisabler):
+ Add implementation for Windows.
+ (WebCore::DenormalDisabler::~DenormalDisabler):
+ Ditto.
+ (WebCore::DenormalDisabler::flushDenormalFloatToZero):
+ Unify Windows with mac/linux.
+ (WebCore::DenormalDisabler::getCSR):
+ Define only if we're not on Windows.
+ (WebCore::DenormalDisabler::setCSR):
+ Ditto.
+
2011-10-20 Alexey Proskuryakov <a...@apple.com>
REGRESSION (r96823): Contextual menu closes immediately when control-clicking in Flash plug-in
Modified: trunk/Source/WebCore/platform/audio/DenormalDisabler.h (98028 => 98029)
--- trunk/Source/WebCore/platform/audio/DenormalDisabler.h 2011-10-20 22:32:19 UTC (rev 98028)
+++ trunk/Source/WebCore/platform/audio/DenormalDisabler.h 2011-10-20 22:39:00 UTC (rev 98029)
@@ -31,26 +31,58 @@
// Deal with denormals. They can very seriously impact performance on x86.
+// Define HAVE_DENORMAL if we support flushing denormals to zero.
+#if OS(WINDOWS) && COMPILER(MSVC)
+#define HAVE_DENORMAL
+#endif
+
#if defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
+#define HAVE_DENORMAL
+#endif
+
+#ifdef HAVE_DENORMAL
class DenormalDisabler {
public:
DenormalDisabler()
+ : m_savedCSR(0)
{
+#if OS(WINDOWS) && COMPILER(MSVC)
+ // Save the current state, and set mode to flush denormals.
+ //
+ // http://stackoverflow.com/questions/637175/possible-bug-in-controlfp-s-may-not-restore-control-word-correctly
+ _controlfp_s(&m_savedCSR, 0, 0);
+ unsigned int unused;
+ _controlfp_s(&unused, _DN_FLUSH, _MCW_DN);
+#else
m_savedCSR = getCSR();
setCSR(m_savedCSR | 0x8040);
+#endif
}
~DenormalDisabler()
{
+#if OS(WINDOWS) && COMPILER(MSVC)
+ unsigned int unused;
+ _controlfp_s(&unused, m_savedCSR, _MCW_DN);
+#else
setCSR(m_savedCSR);
+#endif
}
// This is a nop if we can flush denormals to zero in hardware.
static inline float flushDenormalFloatToZero(float f)
{
+#if OS(WINDOWS) && COMPILER(MSVC) && (!_M_IX86_FP)
+ // For systems using x87 instead of sse, there's no hardware support
+ // to flush denormals automatically. Hence, we need to flush
+ // denormals to zero manually.
+ return (fabs(f) < FLT_MIN) ? 0.0f : f;
+#else
return f;
+#endif
}
private:
+#if defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
inline int getCSR()
{
int result;
@@ -64,25 +96,22 @@
asm volatile("ldmxcsr %0" : : "m" (temp));
}
- int m_savedCSR;
+#endif
+
+ unsigned int m_savedCSR;
};
#else
-// FIXME: add implementations for other architectures and compilers such as Visual Studio.
+// FIXME: add implementations for other architectures and compilers
class DenormalDisabler {
public:
DenormalDisabler() { }
+ // Assume the worst case that other architectures and compilers
+ // need to flush denormals to zero manually.
static inline float flushDenormalFloatToZero(float f)
{
-#if OS(WINDOWS) && COMPILER(MSVC) && (!_M_IX86_FP)
- // For systems using x87 instead of sse, there's no hardware support
- // to flush denormals automatically. Hence, we need to flush
- // denormals to zero manually.
return (fabs(f) < FLT_MIN) ? 0.0f : f;
-#else
- return f;
-#endif
}
};
@@ -90,4 +119,5 @@
} // WebCore
+#undef HAVE_DENORMAL
#endif // DenormalDisabler_h
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