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

[John Regehr via llvm-commits]

regehr added a comment.

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.


Repository:
  rL LLVM

http://reviews.llvm.org/D12706