When doing remat, don't consider uses of non-allocatable physregs.  Patch 
by Evan.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@74370 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/LiveIntervalAnalysis.cpp b/lib/CodeGen/LiveIntervalAnalysis.cpp
index d6931df..21bb5dc 100644
--- a/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -947,6 +947,10 @@
     unsigned Reg = MO.getReg();
     if (Reg == 0 || Reg == li.reg)
       continue;
+    
+    if (TargetRegisterInfo::isPhysicalRegister(Reg) &&
+        !allocatableRegs_[Reg])
+      continue;
     // FIXME: For now, only remat MI with at most one register operand.
     assert(!RegOp &&
            "Can't rematerialize instruction with multiple register operand!");