diff --git a/src/mapleall/maple_me/src/dse.cpp b/src/mapleall/maple_me/src/dse.cpp
index e6b31d30572800bf6eaa5d9186ff21d0fab1117b..17ed67c1bf87b7b4d683c2f15ce8107f92ee23e1 100644
--- a/src/mapleall/maple_me/src/dse.cpp
+++ b/src/mapleall/maple_me/src/dse.cpp
@@ -37,6 +37,10 @@ using namespace utils;
 
 bool DSE::ExprHasSideEffect(const BaseNode &expr) const {
   Opcode op = expr.GetOpCode();
+  // in c language, OP_array and OP_div has no side-effect
+  if (ssaTab.GetModule().IsCModule() && (op == OP_array || op == OP_div)) {
+    return false;
+  }
   if (kOpcodeInfo.HasSideEffect(op)) {
     return true;
   }
diff --git a/src/mapleall/maple_me/src/hdse.cpp b/src/mapleall/maple_me/src/hdse.cpp
index 6326d9581acf8f5fa6dbcb89176b942f73fdd1d8..e09600b96ee312c41e2fc1c6cc86cd1e31ed8f51 100644
--- a/src/mapleall/maple_me/src/hdse.cpp
+++ b/src/mapleall/maple_me/src/hdse.cpp
@@ -378,8 +378,8 @@ void HDSE::PropagateUseLive(MeExpr &meExpr) {
 
 bool HDSE::ExprHasSideEffect(const MeExpr &meExpr) const {
   Opcode op = meExpr.GetOp();
-  // in c language, OP_array has no side-effect
-  if (mirModule.IsCModule() && op == OP_array) {
+  // in c language, OP_array and OP_div has no side-effect
+  if (mirModule.IsCModule() && (op == OP_array || op == OP_div)) {
     return false;
   }
   if (kOpcodeInfo.HasSideEffect(op)) {
diff --git a/src/mapleall/maple_me/src/lfo_iv_canon.cpp b/src/mapleall/maple_me/src/lfo_iv_canon.cpp
index 5b5ba3ecc95b7d020ce1502f44d51cf97f0a7570..a4389619a72e519fab7b119ea4a1655c0ca9c869 100644
--- a/src/mapleall/maple_me/src/lfo_iv_canon.cpp
+++ b/src/mapleall/maple_me/src/lfo_iv_canon.cpp
@@ -40,6 +40,14 @@ bool IVCanon::ResolveExprValue(MeExpr *x, ScalarMeExpr *phiLHS) {
       return false;
     }
     AssignMeStmt *defStmt = static_cast<AssignMeStmt*>(scalar->GetDefStmt());
+    if (defStmt->GetOp() == OP_dassign) {
+      // defstmt is  %post = i, i is identified as IV
+      // set %post is IV and use i's step value
+      scalar = dynamic_cast<ScalarMeExpr *>(defStmt->GetRHS());
+      if (scalar && scalar->GetOst() && IsScalarIV(scalar->GetOst())) {
+        return true;
+      }
+    }
     return ResolveExprValue(defStmt->GetRHS(), phiLHS);
   }
   case kMeOpOp: {  // restricting to only + and - for now
@@ -74,6 +82,17 @@ int32 IVCanon::ComputeIncrAmt(MeExpr *x, ScalarMeExpr *phiLHS, int32 *appearance
       ScalarMeExpr *scalar = static_cast<ScalarMeExpr *>(x);
       CHECK_FATAL(scalar->GetDefBy() == kDefByStmt, "ComputeIncrAmt: cannot be here");
       AssignMeStmt *defstmt = static_cast<AssignMeStmt*>(scalar->GetDefStmt());
+<<<<<<< fredchow_hdse3
+      if (defstmt->GetOp() == OP_dassign) {
+        scalar = dynamic_cast<ScalarMeExpr *>(defstmt->GetRHS());
+        if (scalar && scalar->GetOst() && IsScalarIV(scalar->GetOst())) {
+          int32_t stepVal = 0;
+          if (IsScalarIV(scalar->GetOst(), &stepVal)) {
+            *appearances = 1;
+            return stepVal;
+          }
+        }
+      }
       return ComputeIncrAmt(defstmt->GetRHS(), phiLHS, appearances);
     }
     case kMeOpOp: {