Only test compression when linked with zlib.

I'll implement error handling and a negative test in both llvm-mc and
Clang soon.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205016 91177308-0d34-0410-b5e6-96231b3b80d8
Exception handling docs: Clarify how the llvm.eh.* intrinsics are used

The non-SJLJ and SJLJ intrinsics are generated by the frontend and
backend respectively.

Differential Revision: http://llvm-reviews.chandlerc.com/D3010

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205017 91177308-0d34-0410-b5e6-96231b3b80d8
SLPVectorizer: Ignore users that are insertelements we can reschedule them

Patch by Arch D. Robison!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205018 91177308-0d34-0410-b5e6-96231b3b80d8
SLPVectorizer: Fix typos

Patch by Arch D. Robison!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205019 91177308-0d34-0410-b5e6-96231b3b80d8
SLPVectorizer: Take credit for free extractelement instructions

Extract element instructions that will be removed when vectorzing lower the
cost.

Patch by Arch D. Robison!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205020 91177308-0d34-0410-b5e6-96231b3b80d8