Internals: Fix same() called outside of sameTree (#4561).

src/V3Ast.h

@@ -1773,6 +1773,9 @@ protected:
         UASSERT_STATIC(s_cloneCntGbl, "Rollover");
     }
 
+    // Use instead isSame(), this is for each Ast* class, and assumes node is of same type
+    virtual bool same(const AstNode*) const { return true; }
+
 public:
     // ACCESSORS
     VNType type() const VL_MT_SAFE { return m_type; }
@@ -2137,7 +2140,10 @@ public:
     // statement is unlikely to be taken
     virtual bool isUnlikely() const { return false; }
     virtual int instrCount() const { return 0; }
-    virtual bool same(const AstNode*) const { return true; }
+    // Iff node is identical to anouther node
+    virtual bool isSame(const AstNode* samep) const {
+        return type() == samep->type() && same(samep);
+    }
     // Iff has a data type; dtype() must be non null
     virtual bool hasDType() const VL_MT_SAFE { return false; }
     // Iff has a non-null childDTypep(), as generic node function

src/V3AstNodes.cpp

@@ -1701,7 +1701,7 @@ AstNodeUOrStructDType* AstMemberDType::getChildStructp() const {
 
 bool AstMemberSel::same(const AstNode* samep) const {
     const AstMemberSel* const sp = VN_DBG_AS(samep, MemberSel);
-    return sp != nullptr && access() == sp->access() && fromp()->same(sp->fromp())
+    return sp != nullptr && access() == sp->access() && fromp()->isSame(sp->fromp())
            && name() == sp->name() && varp()->same(sp->varp());
 }
 

src/V3Const.cpp

@@ -1434,7 +1434,7 @@ private:
             // Avoid comparing widthMin's, which results in lost optimization attempts
             // If cleanup sameGateTree to be smarter, this can be restored.
             // return node1p->sameGateTree(node2p);
-            return node1p->same(node2p);
+            return node1p->isSame(node2p);
         } else {
             return false;
         }

src/V3Gate.cpp

@@ -1000,7 +1000,7 @@ static void eliminate(AstNode* logicp,
         // Substitute in the new tree
         UASSERT_OBJ(nodep->access().isReadOnly(), nodep,
                     "Can't replace lvalue assignments with const var");
-        UASSERT_OBJ(!(VN_IS(substp, NodeVarRef) && nodep->same(substp)),
+        UASSERT_OBJ(!(VN_IS(substp, NodeVarRef) && nodep->isSame(substp)),
                     // Prevent an infinite loop...
                     substp, "Replacing node with itself; perhaps circular logic?");
         // The replacement

src/V3Reloop.cpp

@@ -207,10 +207,10 @@ private:
         if (m_mgSelLp) {  // Old merge
             if (m_mgCfuncp == m_cfuncp  // In same function
                 && m_mgNextp == nodep  // Consecutive node
-                && m_mgVarrefLp->same(lvarrefp)  // Same array on left hand side
+                && m_mgVarrefLp->isSame(lvarrefp)  // Same array on left hand side
                 && (m_mgConstRp  // On the right hand side either ...
-                        ? (rconstp && m_mgConstRp->same(rconstp))  // ... same constant
-                        : (rselp && m_mgVarrefRp->same(rvarrefp)))  // ... or same array
+                        ? (rconstp && m_mgConstRp->isSame(rconstp))  // ... same constant
+                        : (rselp && m_mgVarrefRp->isSame(rvarrefp)))  // ... or same array
                 && (lindex == m_mgIndexLo - 1 || lindex == m_mgIndexHi + 1)  // Left index +/- 1
                 && (m_mgConstRp || lindex == rindex + m_mgOffset)  // Same right index offset
             ) {

src/V3Slice.cpp

@@ -135,7 +135,7 @@ class SliceVisitor final : public VNVisitor {
                     const AstUnpackArrayDType* const itemDTypep
                         = VN_CAST(itemRawDTypep, UnpackArrayDType);
                     if (!itemDTypep
-                        || !expectedItemDTypep->same(itemDTypep->subDTypep()->skipRefp())) {
+                        || !expectedItemDTypep->isSame(itemDTypep->subDTypep()->skipRefp())) {
                         if (!m_assignError) {
                             itemp->v3error("Item is incompatible with the array type.");
                         }