Revert r168630, r168631, and r168633 as these are causing nightly test failures.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@168751 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/RegAllocPBQP.cpp b/lib/CodeGen/RegAllocPBQP.cpp
index f58d45f..02ebce7 100644
--- a/lib/CodeGen/RegAllocPBQP.cpp
+++ b/lib/CodeGen/RegAllocPBQP.cpp
@@ -552,6 +552,8 @@
   vrm = &getAnalysis<VirtRegMap>();
   spiller.reset(createInlineSpiller(*this, MF, *vrm));
 
+  mri->freezeReservedRegs(MF);
+
   DEBUG(dbgs() << "PBQP Register Allocating for " << mf->getName() << "\n");
 
   // Allocator main loop: