PR19623: Implement typedefs of void.

This the LLVM portion that will allow Clang and other frontends to emit
typedefs of void by providing a null type for the typedef's underlying
type.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207777 91177308-0d34-0410-b5e6-96231b3b80d8
DebugInfo: Correct the attribute type kind.

Post commit review feedback from Paul Robinson regarding r207777.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207782 91177308-0d34-0410-b5e6-96231b3b80d8
Add an optimization that does CSE in a group of similar GEPs.

This optimization merges the common part of a group of GEPs, so we can compute
each pointer address by adding a simple offset to the common part.

The optimization is currently only enabled for the NVPTX backend, where it has
a large payoff on some benchmarks.

Review: http://reviews.llvm.org/D3462

Patch by Jingyue Wu.




git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207783 91177308-0d34-0410-b5e6-96231b3b80d8