R600/SI: Use s_movk_i32

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221922 91177308-0d34-0410-b5e6-96231b3b80d8
[FastISel][AArch64] Don't bail during simple GEP instruction selection.

The generic FastISel code would bail, because it can't emit a sign-extend for
AArch64. This copies the code over and uses AArch64 specific emit functions.

This is not ideal and 'computeAddress' should handles this, so it can fold the
address computation into the memory operation.

I plan to clean up 'computeAddress' anyways, so I will add that in a future
commit.

Related to rdar://problem/18962471.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221923 91177308-0d34-0410-b5e6-96231b3b80d8
[GVN] Perform Scalar PRE on gep indices that feed loads before doing Load PRE.

Phabricator Revision: http://reviews.llvm.org/D6103
Patch by "Balaram Makam" <bmakam@codeaurora.org>!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221924 91177308-0d34-0410-b5e6-96231b3b80d8