[Support] Fix argv string escape bug on Windows

Summary:
This is http://llvm.org/PR15802.  Backslashes preceding double quotes in
arguments must be escaped.  The interesting bit is that all other
backslashes should *not* be escaped, because the un-escaping logic is
only triggered by the presence of a double quote character.

Reviewers: Bigcheese

CC: llvm-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D705

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@180035 91177308-0d34-0410-b5e6-96231b3b80d8
[ms-inline asm] Remove the identifier parsing logic from the AsmParser.  This is
now taken care of by the frontend, which allows us to parse arbitrary C/C++
variables.
Part of rdar://13663589

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@180037 91177308-0d34-0410-b5e6-96231b3b80d8
[mips] In performDSPShiftCombine, check that all elements in the vector are
shifted by the same amount and the shift amount is smaller than the element
size.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@180039 91177308-0d34-0410-b5e6-96231b3b80d8