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
