Clear the llvm release notes to make room for 3.6.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216292 91177308-0d34-0410-b5e6-96231b3b80d8
ARM / x86_64 varargs: Don't save regparms in prologue without va_start

There's no need to do this if the user doesn't call va_start. In the
future, we're going to have thunks that forward these register
parameters with musttail calls, and they won't need these spills for
handling va_start.

Most of the test suite changes are adding va_start calls to existing
tests to keep things working.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216294 91177308-0d34-0410-b5e6-96231b3b80d8
[SROA] Fold a PHI node if all its incoming values are the same

Summary:
Fixes PR20425.

During slice building, if all of the incoming values of a PHI node are the same, replace the PHI node with the common value. This simplification makes alloca's used by PHI nodes easier to promote.

Test Plan: Added three more tests in phi-and-select.ll

Reviewers: nlewycky, eliben, meheff, chandlerc

Reviewed By: chandlerc

Subscribers: zinovy.nis, hfinkel, baldrick, llvm-commits

Differential Revision: http://reviews.llvm.org/D4659

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216299 91177308-0d34-0410-b5e6-96231b3b80d8