[PATCH] D12706: Handle non-constant shifts in computeKnownBits, and use computeKnownBits for constant folding in InstCombine/Simplify

[hfinkel@anl.gov via llvm-commits]

hfinkel added a comment.

In http://reviews.llvm.org/D12706#251597, @regehr wrote:

> I should add that my patch has no measurable effect on the time taken to build an LLVM/clang/compiler-rt. Also a Debug build of the patched compiler passes all tests.
>
> Also, the clang that gets compiled by a patched compiler is about 4KB smaller than one built with a clang lacking my patch, so it is certainly enabling a few optimizations to fire.


This sounds great. There is a lot of follow-up work to be done here. I'm somewhat fearful of adding more functionality into this patch, it is already pretty far-reaching in terms of potential complications. Once I get this settled, I think it would be best to post follow-up patches for review.


http://reviews.llvm.org/D12706