Don't recalculate the loop info and loop dominators analyses if they're

preserved.

llvm-svn: 45596

llvm/lib/CodeGen/PHIElimination.cpp

@@ -51,6 +51,8 @@ namespace {
 
     virtual void getAnalysisUsage(AnalysisUsage &AU) const {
       AU.addPreserved<LiveVariables>();
+      AU.addPreservedID(MachineLoopInfoID);
+      AU.addPreservedID(MachineDominatorsID);
       MachineFunctionPass::getAnalysisUsage(AU);
     }