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llvm-mirror/lib/Support/MathExtras.cpp
Yaron Keren e5099179f6 Fix llvm::huge_valf multiple initializations with Visual C++.
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.

llvm-svn: 218567
2014-09-27 14:41:29 +00:00

33 lines
885 B
C++

//===-- 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>
#else
#include <math.h>
#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
}