InstCombine: Teach most integer add/sub/mul/div combines how to deal with vectors.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199602 91177308-0d34-0410-b5e6-96231b3b80d8
InstCombine: Replace a hand-rolled version of isKnownToBeAPowerOfTwo with the real thing.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199604 91177308-0d34-0410-b5e6-96231b3b80d8
InstCombine: Hoist 3 copies of AddOne/SubOne into a header.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199605 91177308-0d34-0410-b5e6-96231b3b80d8
InstCombine: Modernize a bunch of cast combines.

Also make them vector-aware.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199608 91177308-0d34-0410-b5e6-96231b3b80d8
[APInt] Fixed bug where APInt(UINT32_MAX, 0) would blow up when being constructed.

This was due to arithmetic overflow in the getNumBits() computation. Now we
cast BitWidth to a uint64_t so that does not occur during the computation. After
the computation is complete, the uint64_t is truncated when the function
returns.

I know that this is not something that is likely to happen, but it *IS* a valid
input and we should not blow up.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199609 91177308-0d34-0410-b5e6-96231b3b80d8
[APInt] Fix nearestLogBase2 to return correct answers for very large APInt and APInt with a bitwidth of 1.

I also improved the comments, added some more tests, etc.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199610 91177308-0d34-0410-b5e6-96231b3b80d8
Move the retrieval of VT after all of the early exits from PerformOrCombine that do not use VT. NFC.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199612 91177308-0d34-0410-b5e6-96231b3b80d8