diff --git a/src/mapleall/maple_me/include/orig_symbol.h b/src/mapleall/maple_me/include/orig_symbol.h
index e4670ba4b05f794b42c9c176a37c00fd651cf12e..3c34b86a173b8063e322089215b385e608e9f48d 100644
--- a/src/mapleall/maple_me/include/orig_symbol.h
+++ b/src/mapleall/maple_me/include/orig_symbol.h
@@ -121,6 +121,16 @@ class OriginalSt {
     return ostType == kPregOst && symOrPreg.pregIdx < 0;
   }
 
+  bool IsSameSymOrPreg(OriginalSt *ost) const {
+    if (ostType != ost->ostType) {
+      return false;
+    }
+    if (IsSymbolOst()) {
+      return symOrPreg.mirSt == ost->symOrPreg.mirSt;
+    }
+    return symOrPreg.pregIdx == ost->symOrPreg.pregIdx;
+  }
+
   int8 GetIndirectLev() const {
     return indirectLev;
   }
diff --git a/src/mapleall/maple_me/src/alias_class.cpp b/src/mapleall/maple_me/src/alias_class.cpp
index 0e0896110abbe1d14afcb0baa9c4ac52e1f2558c..8c042609a2d0b2e810666fd8ded5125b46b85ca7 100644
--- a/src/mapleall/maple_me/src/alias_class.cpp
+++ b/src/mapleall/maple_me/src/alias_class.cpp
@@ -591,7 +591,7 @@ AliasElem *AliasClass::FindOrCreateDummyNADSAe() {
   ASSERT_NOT_NULL(dummySym);
   dummySym->SetIsTmp(true);
   dummySym->SetIsDeleted();
-  OriginalSt *dummyOst = ssaTab.GetOriginalStTable().CreateSymbolOriginalSt(*dummySym, 0, 0);
+  OriginalSt *dummyOst = ssaTab.GetOriginalStTable().FindOrCreateSymbolOriginalSt(*dummySym, 0, 0);
   ssaTab.GetVersionStTable().CreateZeroVersionSt(dummyOst);
   if (osym2Elem.size() == dummyOst->GetIndex()) {
     AliasElem *dummyAe = acMemPool.New<AliasElem>(osym2Elem.size(), *dummyOst);
@@ -984,7 +984,7 @@ void AliasClass::CollectMayDefForDassign(const StmtNode &stmt, std::set<Original
         (void)mayDefOsts.insert(ostOfAliasAe);
       }
     } else {
-      if (ostOfAliasAe->GetMIRSymbol() == ostOfLhsAe->GetMIRSymbol() &&
+      if (ostOfAliasAe->IsSameSymOrPreg(ostOfLhsAe) &&
           fldIDA != fldIDB &&
           lhsSymType->GetKind() != kTypeUnion) {
         MIRType *aliasAeType = GlobalTables::GetTypeTable().GetTypeFromTyIdx(ostOfAliasAe->GetTyIdx());
@@ -1085,8 +1085,8 @@ void AliasClass::CollectMayDefForIassign(StmtNode &stmt, std::set<OriginalSt*> &
       if (ostOfAliasAE.GetTyIdx() != pointedTyIdx && pointedTyIdx != 0) {
         continue;
       }
-    } else if (ostOfAliasAE.IsSymbolOst()) {
-      if (ostOfAliasAE.GetMIRSymbol() == ostOfLhsAe->GetMIRSymbol() &&
+    } else {
+      if (ostOfAliasAE.IsSameSymOrPreg(ostOfLhsAe) &&
           ostOfAliasAE.GetFieldID() != ostOfLhsAe->GetFieldID() &&
           ostOfAliasAE.GetFieldID() != 0 && ostOfLhsAe->GetFieldID() != 0) {
         MIRType *aliasAeType = GlobalTables::GetTypeTable().GetTypeFromTyIdx(ostOfAliasAE.GetTyIdx());
@@ -1202,7 +1202,12 @@ void AliasClass::CollectMayDefForMustDefs(const StmtNode &stmt, std::set<Origina
     for (unsigned int elemID : *(lhsAe->GetClassSet())) {
       bool isNotAllDefsSeen = false;
       for (AliasElem *notAllDefsSeenAe : notAllDefsSeenClassSetRoots) {
-        if (notAllDefsSeenAe->GetClassSet()->find(elemID) != notAllDefsSeenAe->GetClassSet()->end()) {
+        if (notAllDefsSeenAe->GetClassSet() == nullptr) {
+          if (elemID == notAllDefsSeenAe->GetClassID()) {
+            isNotAllDefsSeen = true;
+            break;  // inserted already
+          }
+        } else if (notAllDefsSeenAe->GetClassSet()->find(elemID) != notAllDefsSeenAe->GetClassSet()->end()) {
           isNotAllDefsSeen = true;
           break;  // inserted already
         }
diff --git a/src/mapleall/maple_me/src/hdse.cpp b/src/mapleall/maple_me/src/hdse.cpp
index 36efa6b951a24631a412fb07c4559f57e511aaa2..561ea7be24cb5cbcae4dbce5bc92deb14c8692f9 100644
--- a/src/mapleall/maple_me/src/hdse.cpp
+++ b/src/mapleall/maple_me/src/hdse.cpp
@@ -173,6 +173,15 @@ void HDSE::MarkRegDefByStmt(RegMeExpr &regMeExpr) {
     case kDefByPhi:
       MarkPhiRequired(regMeExpr.GetDefPhi());
       break;
+    case kDefByChi: {
+      ASSERT(regMeExpr.GetOst()->GetIndirectLev() > 0, 
+             "MarkRegDefByStmt: preg cannot be defined by chi");
+      auto *defChi = &regMeExpr.GetDefChi();
+      if (defChi != nullptr) {
+        MarkChiNodeRequired(*defChi);
+      }
+      break;
+    }
     case kDefByMustDef: {
       MustDefMeNode *mustDef = &regMeExpr.GetDefMustDef();
       if (!mustDef->GetIsLive()) {
diff --git a/src/mapleall/maple_me/src/irmap_build.cpp b/src/mapleall/maple_me/src/irmap_build.cpp
index 71af6a79fc424ff1bfbfb535370bc59bf30fff12..12e42f01875e9c9e567f7939d5bdbaaec8fe2d43 100644
--- a/src/mapleall/maple_me/src/irmap_build.cpp
+++ b/src/mapleall/maple_me/src/irmap_build.cpp
@@ -91,8 +91,12 @@ void IRMapBuild::BuildMustDefList(MeStmt &meStmt, TypeOfMustDefList &mustDefList
                                   MapleVector<MustDefMeNode> &mustDefMeList) {
   for (auto &mustDefNode : mustDefList) {
     VersionSt *vst = mustDefNode.GetResult();
-    VarMeExpr *lhs = GetOrCreateVarFromVerSt(*vst);
-    ASSERT(lhs->GetMeOp() == kMeOpReg || lhs->GetMeOp() == kMeOpVar, "unexpected opcode");
+    ScalarMeExpr *lhs = nullptr;
+    if (vst->GetOst()->IsSymbolOst()) {
+      lhs = GetOrCreateVarFromVerSt(*vst);
+    } else {
+      lhs = GetOrCreateRegFromVerSt(*vst);
+    }
     mustDefMeList.emplace_back(MustDefMeNode(lhs, &meStmt));
   }
 }
diff --git a/src/mapleall/maple_me/src/prop.cpp b/src/mapleall/maple_me/src/prop.cpp
index d6e588de52cd56ad2a27834c216cc88803e4bd1f..2b01e7de1a9481f3599e43742c144339255ef378 100644
--- a/src/mapleall/maple_me/src/prop.cpp
+++ b/src/mapleall/maple_me/src/prop.cpp
@@ -561,7 +561,6 @@ void Prop::TraversalMeStmt(MeStmt &meStmt) {
     MapleVector<MustDefMeNode> *mustDefList = meStmt.GetMustDefList();
     for (auto &node : utils::ToRef(mustDefList)) {
       MeExpr *meLhs = node.GetLHS();
-      CHECK_FATAL(meLhs->GetMeOp() == kMeOpVar, "error: lhs is not var");
       PropUpdateDef(utils::ToRef(static_cast<VarMeExpr*>(meLhs)));
     }
   }