[Modules] Use global index to improve typo correction performance

Typo correction for an unqualified name needs to walk through all of the identifier tables of all modules.
When we have a global index, just walk its identifier table only.

rdar://13425732

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@179730 91177308-0d34-0410-b5e6-96231b3b80d8
[analyzer] Allow TrackConstraintBRVisitor to work when the value it’s tracking is not live in the last node of the path

We always register the visitor on a node in which the value we are tracking is live and constrained. However,
the visitation can restart at a node, later on the path, in which the value is under constrained because
it is no longer live. Previously, we just silently stopped tracking in that case.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@179731 91177308-0d34-0410-b5e6-96231b3b80d8
[analyzer] Gain more precision retrieving the right SVal by specifying the type of the expression.

Thanks to Jordan for suggesting the fix.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@179732 91177308-0d34-0410-b5e6-96231b3b80d8
Add description of -Ofast optimization option to the man page. <rdar://13660458>

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@179733 91177308-0d34-0410-b5e6-96231b3b80d8