Fix initiation of function variables (#3815).

src/V3AstNodes.cpp

@@ -2092,6 +2092,7 @@ void AstVar::dump(std::ostream& str) const {
     if (isSigPublic()) str << " [P]";
     if (isLatched()) str << " [LATCHED]";
     if (isUsedLoopIdx()) str << " [LOOP]";
+    if (noReset()) str << " [!RST]";
     if (attrIsolateAssign()) str << " [aISO]";
     if (attrFileDescr()) str << " [aFD]";
     if (isFuncReturn()) {

src/V3CCtors.cpp

@@ -138,6 +138,7 @@ private:
 
     // STATE
     AstNodeModule* m_modp = nullptr;  // Current module
+    AstCFunc* m_cfuncp = nullptr;  // Current function
     V3CCtorsBuilder* m_varResetp = nullptr;  // Builder of _ctor_var_reset
 
     // VISITs
@@ -172,16 +173,23 @@ private:
 
     void visit(AstCFunc* nodep) override {
         VL_RESTORER(m_varResetp);
+        VL_RESTORER(m_cfuncp);
         m_varResetp = nullptr;
+        m_cfuncp = nodep;
         iterateChildren(nodep);
     }
     void visit(AstVar* nodep) override {
-        if (m_varResetp && !nodep->isIfaceParent() && !nodep->isIfaceRef() && !nodep->noReset()
-            && !nodep->isParam()
+        if (!nodep->isIfaceParent() && !nodep->isIfaceRef() && !nodep->noReset()
+            && !nodep->isParam() && !nodep->isStatementTemp()
             && !(nodep->basicp()
                  && (nodep->basicp()->isEvent() || nodep->basicp()->isTriggerVec()))) {
-            const auto vrefp = new AstVarRef{nodep->fileline(), nodep, VAccess::WRITE};
-            m_varResetp->add(new AstCReset{nodep->fileline(), vrefp});
+            if (m_varResetp) {
+                const auto vrefp = new AstVarRef{nodep->fileline(), nodep, VAccess::WRITE};
+                m_varResetp->add(new AstCReset{nodep->fileline(), vrefp});
+            } else if (m_cfuncp) {
+                const auto vrefp = new AstVarRef{nodep->fileline(), nodep, VAccess::WRITE};
+                nodep->addNextHere(new AstCReset{nodep->fileline(), vrefp});
+            }
         }
     }
 

src/V3EmitCFunc.cpp

@@ -578,8 +578,9 @@ void EmitCFunc::emitSetVarConstant(const string& assignString, AstConst* constp)
 
 void EmitCFunc::emitVarReset(AstVar* varp) {
     AstNodeDType* const dtypep = varp->dtypep()->skipRefp();
-    const string varNameProtected
-        = VN_IS(m_modp, Class) ? varp->nameProtect() : "vlSelf->" + varp->nameProtect();
+    const string varNameProtected = (VN_IS(m_modp, Class) || varp->isFuncLocal())
+                                        ? varp->nameProtect()
+                                        : "vlSelf->" + varp->nameProtect();
     if (varp->isIO() && m_modp->isTop() && optSystemC()) {
         // System C top I/O doesn't need loading, as the lower level subinst code does it.}
     } else if (varp->isParam()) {
@@ -697,9 +698,11 @@ string EmitCFunc::emitVarResetRecurse(const AstVar* varp, const string& varNameP
     } else if (basicp) {
         const bool zeroit
             = (varp->attrFileDescr()  // Zero so we don't do file IO if never $fopen
+               || varp->isFuncLocal()  // Randomization too slow
                || (basicp && basicp->isZeroInit())
                || (v3Global.opt.underlineZero() && !varp->name().empty() && varp->name()[0] == '_')
                || (v3Global.opt.xInitial() == "fast" || v3Global.opt.xInitial() == "0"));
+        const bool slow = !varp->isFuncLocal() && !varp->isClassMember();
         splitSizeInc(1);
         if (dtypep->isWide()) {  // Handle unpacked; not basicp->isWide
             string out;
@@ -711,7 +714,7 @@ string EmitCFunc::emitVarResetRecurse(const AstVar* varp, const string& varNameP
                     out += cvtToStr(constp->num().edataWord(w)) + "U;\n";
                 }
             } else {
-                out += zeroit ? "VL_ZERO_RESET_W(" : "VL_RAND_RESET_W(";
+                out += zeroit ? (slow ? "VL_ZERO_RESET_W(" : "VL_ZERO_W(") : "VL_RAND_RESET_W(";
                 out += cvtToStr(dtypep->widthMin());
                 out += ", " + varNameProtected + suffix + ");\n";
             }

src/V3Localize.cpp

@@ -108,6 +108,7 @@ private:
                 AstVar* const newVarp
                     = new AstVar{oldVarp->fileline(), oldVarp->varType(), newName, oldVarp};
                 newVarp->funcLocal(true);
+                newVarp->noReset(oldVarp->noReset());
                 funcp->addInitsp(newVarp);
 
                 // Fix up all the references within this function

src/V3Sched.cpp

@@ -554,6 +554,7 @@ AstNodeStmt* buildLoop(AstNetlist* netlistp, const string& name,
     FileLine* const flp = scopeTopp->fileline();
     // Create the loop condition variable
     AstVarScope* const condp = scopeTopp->createTemp("__V" + name + "Continue", 1);
+    condp->varp()->noReset(true);
     // Initialize the loop condition variable to true
     AstNodeStmt* const resp = setVar(condp, 1);
     // Add the loop
@@ -578,6 +579,7 @@ std::pair<AstVarScope*, AstNodeStmt*> makeEvalLoop(AstNetlist* netlistp, const s
     FileLine* const flp = scopeTopp->fileline();
 
     AstVarScope* const counterp = scopeTopp->createTemp("__V" + tag + "IterCount", 32);
+    counterp->varp()->noReset(true);
 
     AstNodeStmt* nodep = setVar(counterp, 0);
     nodep->addNext(buildLoop(netlistp, tag, [&](AstVarScope* continuep, AstWhile* loopp) {