Fix llvm::huge_valf multiple initialization (VC)

[Yaron Keren]

 llvm::huge_valf is defined in a header file, so it is initialized multiple
times in every compiled unit upon program startup.  With non-VC
compilers huge_valf  is set to a HUGE_VALF which the compiler can probably
optimize out.

With VC numeric_limits<float>::infinity() does not return a number but a
runtime structure member which therotically may change between calls so the
compiler does not optimize out the initialization and it happens many
times. It can be easily seen by placing a breakpoint on the initialization
line.

This patch moves llvm::huge_valf  initialization to a source file instead
of the header.
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Index: include/llvm/Support/MathExtras.h
===================================================================
--- include/llvm/Support/MathExtras.h	(revision 218559)
+++ include/llvm/Support/MathExtras.h	(working copy)
@@ -22,7 +22,6 @@
 
 #ifdef _MSC_VER
 #include <intrin.h>
-#include <limits>
 #endif
 
 namespace llvm {
@@ -639,13 +638,7 @@
   return int64_t(X << (64 - B)) >> (64 - B);
 }
 
-#if defined(_MSC_VER)
-  // Visual Studio defines the HUGE_VAL class of macros using purposeful
-  // constant arithmetic overflow, which it then warns on when encountered.
-  const float huge_valf = std::numeric_limits<float>::infinity();
-#else
-  const float huge_valf = HUGE_VALF;
-#endif
+extern const float huge_valf;
 } // End llvm namespace
 
 #endif
Index: lib/Support/CMakeLists.txt
===================================================================
--- lib/Support/CMakeLists.txt	(revision 218559)
+++ lib/Support/CMakeLists.txt	(working copy)
@@ -36,6 +36,7 @@
   Locale.cpp
   LockFileManager.cpp
   ManagedStatic.cpp
+  MathExtras.cpp
   MemoryBuffer.cpp
   MemoryObject.cpp
   MD5.cpp
Index: lib/Support/MathExtras.cpp
===================================================================
--- lib/Support/MathExtras.cpp	(revision 0)
+++ lib/Support/MathExtras.cpp	(working copy)
@@ -0,0 +1,30 @@
+//===-- MathExtras.cpp - Implement the MathExtras header --------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the MathExtras.h header
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/MathExtras.h"
+
+#ifdef _MSC_VER
+#include <limits>
+#endif
+
+namespace llvm {
+
+#if defined(_MSC_VER)
+  // Visual Studio defines the HUGE_VAL class of macros using purposeful
+  // constant arithmetic overflow, which it then warns on when encountered.
+  const float huge_valf = std::numeric_limits<float>::infinity();
+#else
+  const float huge_valf = HUGE_VALF;
+#endif
+
+}
\ No newline at end of file

Property changes on: lib/Support/MathExtras.cpp
___________________________________________________________________
Added: svn:eol-style
## -0,0 +1 ##
+native
\ No newline at end of property