[llvm-commits] [llvm] r57124 - /llvm/trunk/utils/TableGen/CodeEmitterGen.cpp

[Chris Lattner]

On Oct 5, 2008, at 2:16 PM, Daniel Dunbar wrote:

>
> -            unsigned opMask = (1 << N) - 1;
> +            unsigned opMask = ~0U >> (32-N);
>
> Would it be unreasonable to pull this until a utility header? I find
> something like
> --
> unsigned opMask = bits32::maxValueOfNBits(N);
> --
> more readable & easier to verify.
>
> Other things I put there are: truncateToNBits, isPowerOfTwo,
> withoutRightmostBit, isolateRightmostBit and indexOfSingleBit.

Sure, this could go into MathExtras.h.  It would be nice to make the  
MathExtras.h and APInt apis as similar as possible though (except that  
MathExtras should have _32/_64 suffixes and always return int32/64 of  
course)

-Chris