Fix style.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221547 91177308-0d34-0410-b5e6-96231b3b80d8
Transform: add SymbolRewriter pass

This introduces the symbol rewriter. This is an IR->IR transformation that is
implemented as a CodeGenPrepare pass. This allows for the transparent
adjustment of the symbols during compilation.

It provides a clean, simple, elegant solution for symbol inter-positioning. This
technique is often used, such as in the various sanitizers and performance
analysis.

The control of this is via a custom YAML syntax map file that indicates source
to destination mapping, so as to avoid having the compiler to know the exact
details of the source to destination transformations.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221548 91177308-0d34-0410-b5e6-96231b3b80d8
Remove unused variable.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221549 91177308-0d34-0410-b5e6-96231b3b80d8
Transforms: use typedef rather than using aliases

Visual Studio 2012 apparently does not support using alias declarations.  Use
the more traditional typedef approach.  This should let the Windows buildbots
pass.  NFC.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221554 91177308-0d34-0410-b5e6-96231b3b80d8
[Reassociate] Better preserve NSW/NUW flags.
Part of PR12985.

Phabricator Revision: http://reviews.llvm.org/D6172

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221555 91177308-0d34-0410-b5e6-96231b3b80d8