Add an option to enable StrongPHIElimination, for ease of testing.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@57259 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/RegAllocLinearScan.cpp

@@ -26,6 +26,7 @@
 #include "llvm/CodeGen/RegisterCoalescer.h"
 #include "llvm/Target/TargetRegisterInfo.h"
 #include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetOptions.h"
 #include "llvm/Target/TargetInstrInfo.h"
 #include "llvm/ADT/EquivalenceClasses.h"
 #include "llvm/ADT/Statistic.h"
@@ -107,6 +108,8 @@ namespace {
 
     virtual void getAnalysisUsage(AnalysisUsage &AU) const {
       AU.addRequired<LiveIntervals>();
+      if (StrongPHIElim)
+        AU.addRequiredID(StrongPHIEliminationID);
       // Make sure PassManager knows which analyses to make available
       // to coalescing and which analyses coalescing invalidates.
       AU.addRequiredTransitive<RegisterCoalescer>();