[CodeGen][NPM] VirtRegRewriter: Set VirtReg flag (#148107)

same as llvm/llvm-project#138660,

Co-authored-by : Oke, Akshat
<[[email protected]](mailto:[email protected])>

Author: vikramRH

llvm/include/llvm/CodeGen/VirtRegMap.h

@@ -251,6 +251,14 @@ class VirtRegRewriterPass : public PassInfoMixin<VirtRegRewriterPass> {
 
   LLVM_ABI void printPipeline(raw_ostream &OS,
                               function_ref<StringRef(StringRef)>) const;
+
+  MachineFunctionProperties getSetProperties() const {
+    if (ClearVirtRegs) {
+      return MachineFunctionProperties().set(
+          MachineFunctionProperties::Property::NoVRegs);
+    }
+    return {};
+  }
 };
 
 } // end llvm namespace

llvm/lib/CodeGen/VirtRegMap.cpp

@@ -301,6 +301,8 @@ bool VirtRegRewriterLegacy::runOnMachineFunction(MachineFunction &MF) {
 PreservedAnalyses
 VirtRegRewriterPass::run(MachineFunction &MF,
                          MachineFunctionAnalysisManager &MFAM) {
+  MFPropsModifier _(*this, MF);
+
   VirtRegMap &VRM = MFAM.getResult<VirtRegMapAnalysis>(MF);
   LiveIntervals &LIS = MFAM.getResult<LiveIntervalsAnalysis>(MF);
   LiveRegMatrix &LRM = MFAM.getResult<LiveRegMatrixAnalysis>(MF);