Subzero: Simplify the FakeKill instruction.

src/IceTargetLowering.cpp

Index: src/IceTargetLowering.cpp
diff --git a/src/IceTargetLowering.cpp b/src/IceTargetLowering.cpp
index 5661ad910adf79d0b786f122ef11e7144516d67d..c8f504e9770191b2443a3e73ea5c920f5630b759 100644
--- a/src/IceTargetLowering.cpp
+++ b/src/IceTargetLowering.cpp
@@ -234,6 +234,7 @@ void TargetLowering::regAlloc() {
   RegInclude |= RegSet_CalleeSave;
   if (hasFramePointer())
     RegExclude |= RegSet_FramePointer;
+  LinearScan.initForGlobalAlloc();
   llvm::SmallBitVector RegMask = getRegisterSet(RegInclude, RegExclude);
   LinearScan.scan(RegMask);
 }