Added do & switch statements, more hacking at the code state thing.

js/js2/icodegenerator.cpp

@@ -144,24 +144,37 @@ void ICodeGenerator::setLabel(int32 label)
     l->itsOffset = iCode->size();
 }
 
+void ICodeGenerator::setLabel(InstructionStream *stream, int32 label)
+{
+    Label* l;
+#ifdef __GNUC__
+    // libg++'s vector class doesn't have at():
+    if (label >= labels.size())
+        throw std::out_of_range("label out of range");
+    l = labels[label];
+#else
+    l = labels.at(label);
+#endif
+    l->itsBase = stream;
+    l->itsOffset = stream->size();
+}
+
 /***********************************************************************************************/
 
 void MultiPathICodeState::mergeStream(InstructionStream *mainStream, LabelList &labels)
 {
-    if (itsTopLabel < labels.size()) { 
-            // labels (might) have been allocated in this stream
-            // we need to adjust their position relative to the 
-            // size of the stream we're joining
-        for (LabelList::iterator i = labels.begin() + itsTopLabel; i != labels.end(); i++) {
-            if ((*i)->itsBase == its_iCode) {
-                (*i)->itsBase = mainStream;
-                (*i)->itsOffset += mainStream->size();
-            }
+    // change InstructionStream to be a class that also remembers
+    // if it contains any labels (maybe even remembers the labels
+    // themselves?) in order to avoid running this loop unnecessarily.
+    for (LabelList::iterator i = labels.begin(); i != labels.end(); i++) {
+        if ((*i)->itsBase == its_iCode) {
+            (*i)->itsBase = mainStream;
+            (*i)->itsOffset += mainStream->size();
         }
     }
 
-    for (InstructionIterator i = its_iCode->begin(); i != its_iCode->end(); i++)
-        mainStream->push_back(*i);
+    for (InstructionIterator ii = its_iCode->begin(); ii != its_iCode->end(); ii++)
+        mainStream->push_back(*ii);
 
 }
 
@@ -178,43 +191,176 @@ void ICodeGenerator::beginWhileStatement(const SourcePosition &pos)
     branch(whileConditionTop);
     
     // save off the current stream while we gen code for the condition
-    stitcher.push(new WhileCodeState(iCode, labels.size(), whileConditionTop, whileBlockStart));
+    stitcher.push_back(new WhileCodeState(whileConditionTop, whileBlockStart, this));
 
     iCode = new InstructionStream();
 }
 
 void ICodeGenerator::endWhileExpression(Register condition)
 {
-    WhileCodeState *ics = static_cast<WhileCodeState *>(stitcher.top());
-    ASSERT(ics->stateKind == While_State);
+    WhileCodeState *ics = static_cast<WhileCodeState *>(stitcher.back());
+    ASSERT(ics->stateKind == While_state);
 
-    branchConditional(ics->whileBodyLabel, condition);
+    branchConditional(ics->whileBody, condition);
     resetTopRegister();
     // stash away the condition expression and switch 
     // back to the main stream
     iCode = ics->swapStream(iCode);
-    setLabel(ics->whileBodyLabel);         // mark the start of the while block
+    setLabel(ics->whileBody);         // mark the start of the while block
 }
   
 void ICodeGenerator::endWhileStatement()
 {
     // recover the while stream
-    WhileCodeState *ics = static_cast<WhileCodeState *>(stitcher.top());
-    ASSERT(ics->stateKind == While_State);
-    stitcher.pop();
+    WhileCodeState *ics = static_cast<WhileCodeState *>(stitcher.back());
+    ASSERT(ics->stateKind == While_state);
+    stitcher.pop_back();
 
     // mark the start of the condition code
     // and re-attach it to the main stream
-    setLabel(ics->whileConditionLabel);
+    setLabel(ics->whileCondition);
 
     ics->mergeStream(iCode, labels);
+    if (ics->breakLabel != -1)
+        setLabel(ics->breakLabel);
 
-    delete ics->its_iCode;
     delete ics;
 
     resetTopRegister();
 }
 
+/***********************************************************************************************/
+
+void ICodeGenerator::beginDoStatement(const SourcePosition &pos)
+{
+    resetTopRegister();
+  
+    // mark the top of the loop body
+    // and reserve a label for the condition
+    int32 doBlock = getLabel();
+    int32 doCondition = getLabel();
+    setLabel(doBlock);
+    
+    stitcher.push_back(new DoCodeState(doBlock, doCondition, this));
+
+    iCode = new InstructionStream();
+}
+
+void ICodeGenerator::endDoStatement()
+{
+    DoCodeState *ics = static_cast<DoCodeState *>(stitcher.back());
+    ASSERT(ics->stateKind == Do_state);
+
+    // mark the start of the do conditional
+    setLabel(ics->doCondition);
+
+    resetTopRegister();
+}
+  
+void ICodeGenerator::endDoExpression(Register condition)
+{
+    DoCodeState *ics = static_cast<DoCodeState *>(stitcher.back());
+    ASSERT(ics->stateKind == Do_state);
+    stitcher.pop_back();
+
+    // add branch to top of do block
+    branchConditional(ics->doBody, condition);
+    if (ics->breakLabel != -1)
+        setLabel(ics->breakLabel);
+
+    delete ics;
+
+    resetTopRegister();
+}
+
+/***********************************************************************************************/
+
+void ICodeGenerator::beginSwitchStatement(const SourcePosition &pos, Register expression)
+{
+    // stash the control expression value
+    resetTopRegister();
+    op(MOVE_TO, getRegister(), expression);
+    // build an instruction stream for the case statements, the case
+    // expressions are generated into the main stream directly, the
+    // case statements are then added back in afterwards.
+    InstructionStream *x = new InstructionStream();
+    SwitchCodeState *ics = new SwitchCodeState(expression, this);
+    ics->swapStream(x);
+    stitcher.push_back(ics);
+}
+
+void ICodeGenerator::endCaseCondition(Register expression)
+{
+    SwitchCodeState *ics = static_cast<SwitchCodeState *>(stitcher.back());
+    ASSERT(ics->stateKind == Switch_state);
+
+    int32 caseLabel = getLabel();
+    Register r = op(COMPARE, expression, ics->controlExpression);
+    branchConditional(caseLabel, r);
+
+    setLabel(ics->its_iCode, caseLabel);                // mark the case in the Case Statement stream 
+    resetTopRegister();
+}
+
+void ICodeGenerator::beginCaseStatement()
+{
+    SwitchCodeState *ics = static_cast<SwitchCodeState *>(stitcher.back());
+    ASSERT(ics->stateKind == Switch_state);
+    iCode = ics->swapStream(iCode);                     // switch to Case Statement stream
+}
+
+void ICodeGenerator::endCaseStatement()
+{
+    SwitchCodeState *ics = static_cast<SwitchCodeState *>(stitcher.back());
+    ASSERT(ics->stateKind == Switch_state);             // do more to guarantee correct blocking?
+    iCode = ics->swapStream(iCode);                     // switch back to Case Conditional stream
+    resetTopRegister();
+}
+
+void ICodeGenerator::beginDefaultStatement()
+{
+    SwitchCodeState *ics = static_cast<SwitchCodeState *>(stitcher.back());
+    ASSERT(ics->stateKind == Switch_state);
+    ASSERT(ics->defaultLabel == -1);
+    ics->defaultLabel = getLabel();
+    setLabel(ics->its_iCode, ics->defaultLabel);
+    iCode = ics->swapStream(iCode);                    // switch to Case Statement stream
+}
+
+void ICodeGenerator::endDefaultStatement()
+{
+    SwitchCodeState *ics = static_cast<SwitchCodeState *>(stitcher.back());
+    ASSERT(ics->stateKind == Switch_state);
+    ASSERT(ics->defaultLabel != -1);            // do more to guarantee correct blocking?
+    iCode = ics->swapStream(iCode);             // switch to Case Statement stream
+    resetTopRegister();
+}
+
+void ICodeGenerator::endSwitchStatement()
+{
+    SwitchCodeState *ics = static_cast<SwitchCodeState *>(stitcher.back());
+    ASSERT(ics->stateKind == Switch_state);
+    stitcher.pop_back();
+
+    // ground out the case chain at the default block or fall thru
+    // to the break label
+    if (ics->defaultLabel != -1)       
+        branch(ics->defaultLabel);
+    else {
+        if (ics->breakLabel == -1)
+            ics->breakLabel = getLabel();
+        branch(ics->breakLabel);
+    }
+    
+    // dump all the case statements into the main stream
+    ics->mergeStream(iCode, labels);
+
+    if (ics->breakLabel != -1)
+        setLabel(ics->breakLabel);
+
+    delete ics;
+}
+
 
 /***********************************************************************************************/
 
@@ -222,7 +368,7 @@ void ICodeGenerator::beginIfStatement(const SourcePosition &pos, Register condit
 {
     int32 elseLabel = getLabel();
     
-    stitcher.push(new IfCodeState(elseLabel, -1));
+    stitcher.push_back(new IfCodeState(elseLabel, -1, this));
 
     Register notCond = op(NOT, condition);
     branchConditional(elseLabel, notCond);
@@ -232,8 +378,8 @@ void ICodeGenerator::beginIfStatement(const SourcePosition &pos, Register condit
 
 void ICodeGenerator::beginElseStatement(bool hasElse)
 {
-    IfCodeState *ics = static_cast<IfCodeState *>(stitcher.top());
-    ASSERT(ics->stateKind == If_State);
+    IfCodeState *ics = static_cast<IfCodeState *>(stitcher.back());
+    ASSERT(ics->stateKind == If_state);
 
     if (hasElse) {
         int32 beyondElse = getLabel();
@@ -246,35 +392,54 @@ void ICodeGenerator::beginElseStatement(bool hasElse)
 
 void ICodeGenerator::endIfStatement()
 {
-    IfCodeState *ics = static_cast<IfCodeState *>(stitcher.top());
-    ASSERT(ics->stateKind == If_State);
+    IfCodeState *ics = static_cast<IfCodeState *>(stitcher.back());
+    ASSERT(ics->stateKind == If_state);
+    stitcher.pop_back();
 
     if (ics->beyondElse != -1) {     // had an else
         setLabel(ics->beyondElse);   // the beyond else label
     }
-    stitcher.pop();
+    
+    delete ics;
     resetTopRegister();
 }
 
+/***********************************************************************************************/
+
+void ICodeGenerator::breakStatement()
+{
+    for (std::vector<ICodeState *>::reverse_iterator p = stitcher.rbegin(); p != stitcher.rend(); p++) {
+        
+// this is NOT going to stay this way
+        
+        if (((*p)->stateKind == While_state)
+                || ((*p)->stateKind == Do_state)
+                || ((*p)->stateKind == For_state)
+                || ((*p)->stateKind == Switch_state)) {
+            if ((*p)->breakLabel == -1)
+                (*p)->breakLabel = getLabel();
+            branch((*p)->breakLabel);
+            return;
+        }
+    }
+    NOT_REACHED("no break target available");
+}
 
 /***********************************************************************************************/
 
 
 char *opcodeName[] = {
+        "move_to",
         "load_var",
         "save_var",
-
         "load_imm",
-
         "load_name",
         "save_name",
-
         "get_prop",
         "set_prop", 
-
         "add",
+        "compare",
         "not",
-
         "branch",
         "branch_cond",
 };
@@ -330,11 +495,13 @@ ostream &ICodeGenerator::print(ostream &s)
                 }
                 break;
             case ADD :
+            case COMPARE :
                 {
                      Instruction_3<Register, Register, Register> *t = static_cast<Instruction_3<Register, Register, Register> * >(instr);
                      s << "R" << t->itsOperand1 << ", R" << t->itsOperand2 << ", R" << t->itsOperand3;
                 }
                 break;
+            case MOVE_TO :
             case NOT :
                 {
                      Instruction_3<Register, Register, Register> *t = static_cast<Instruction_3<Register, Register, Register> * >(instr);

js/js2/icodegenerator.h

@@ -34,6 +34,8 @@ namespace JavaScript {
     enum ICodeOp {
                         //      Operand1                Operand2                Operand3
 
+        MOVE_TO,        // Source Register          Destination Register
+
         LOAD_VAR,       // index of frame slot      Destination Register
         SAVE_VAR,       // index of frame slot      Source Register
 
@@ -46,6 +48,7 @@ namespace JavaScript {
         SET_PROP,       // StringAtom &             Base Register               Source Register
 
         ADD,            // Source Register 1        Source Register 2           Destination Register
+        COMPARE,        // Source Register 1        Source Register 2           Destination Register
         NOT,            // Source Register          Destination Register
 
         BRANCH,         // Target label
@@ -104,46 +107,66 @@ namespace JavaScript {
     /****************************************************************/
     /****************************************************************/
 
-    enum StateKind { While_State, If_State };
+    class ICodeGenerator;   // forward declaration
 
-    class ICodeState { 
+    enum StateKind { While_state, If_state, Do_state, Switch_state, For_state };
+
+    class ICodeState {
     public :
-        ICodeState(StateKind kind) : stateKind(kind) { }
+        ICodeState(StateKind kind, ICodeGenerator *icg);        // inline below
         StateKind stateKind;
+        int32 breakLabel;
+        int32 continueLabel;
+        int32 registerBase;
     };
 
     // an ICodeState that handles switching to a new InstructionStream 
     // and then re-combining the streams later
     class MultiPathICodeState : public ICodeState {
     public:
-        MultiPathICodeState(StateKind kind,InstructionStream *iCode, int32 topLabel)
-                            : ICodeState(kind), its_iCode(iCode), itsTopLabel(topLabel) {}
+        MultiPathICodeState(StateKind kind, ICodeGenerator *icg);        // inline below
+        virtual ~MultiPathICodeState()  { delete its_iCode; }
 
         InstructionStream *swapStream(InstructionStream *iCode) { InstructionStream *t = its_iCode; its_iCode = iCode; return t; }
 
         InstructionStream *its_iCode;
-        int32 itsTopLabel;      // set to the highest label allocated when this stream
-                                // was created. If that value changes, this stream may
-                                // contain labels that will need to be adjusted when
-                                // the streams are merged.
+
         void mergeStream(InstructionStream *mainStream, LabelList &labels);
     };
 
     class WhileCodeState : public MultiPathICodeState {
     public:
-        WhileCodeState(InstructionStream *iCode, int32 topLabel, int32 a, int32 b) 
-                    : MultiPathICodeState(While_State, iCode, topLabel), whileConditionLabel(a), whileBodyLabel(b) { }
-        int32 whileConditionLabel;
-        int32 whileBodyLabel;
+        WhileCodeState(int32 conditionLabel, int32 bodyLabel, ICodeGenerator *icg) 
+                    : MultiPathICodeState(While_state, icg), whileCondition(conditionLabel), whileBody(bodyLabel) { }
+        int32 whileCondition;
+        int32 whileBody;
     };
 
     class IfCodeState : public ICodeState {
     public:
-        IfCodeState(int32 a, int32 b) : ICodeState(If_State), elseLabel(a), beyondElse(b) { }
+        IfCodeState(int32 a, int32 b, ICodeGenerator *icg) 
+                    : ICodeState(If_state, icg), elseLabel(a), beyondElse(b) { }
         int32 elseLabel;
         int32 beyondElse;
     };
 
+    class DoCodeState : public ICodeState {
+    public:
+        DoCodeState(int32 bodyLabel, int32 conditionLabel, ICodeGenerator *icg) 
+                    : ICodeState(Do_state, icg), doBody(bodyLabel), doCondition(conditionLabel) { }
+        int32 doBody;
+        int32 doCondition;
+    };
+
+    class SwitchCodeState : public MultiPathICodeState {
+    public:
+        SwitchCodeState(Register control, ICodeGenerator *icg) 
+                    : MultiPathICodeState(Switch_state, icg), controlExpression(control), defaultLabel(-1) { }
+        
+        Register controlExpression;
+        int32 defaultLabel;
+    };
+
     /****************************************************************/
         
     // An ICodeGenerator provides the interface between the parser and the interpreter.
@@ -157,20 +180,21 @@ namespace JavaScript {
         
         LabelList labels;
 
-        std::stack<ICodeState *> stitcher;
+        std::vector<ICodeState *> stitcher;
 
         Register topRegister;
         Register getRegister()      { return topRegister++; }
-        void resetTopRegister()     { topRegister = 0; }
+        void resetTopRegister()     { topRegister = stitcher.empty() ? 0 : stitcher.back()->registerBase; }
 
         int32 getLabel();
         void setLabel(int32 label);
+        void setLabel(InstructionStream *stream, int32 label);
 
         void branch(int32 label);
         void branchConditional(int32 label, Register condition);
     
     public:
-        ICodeGenerator() { iCode = new InstructionStream(); }
+        ICodeGenerator() : topRegister(0) { iCode = new InstructionStream(); }
 
         InstructionStream *complete();
 
@@ -187,8 +211,8 @@ namespace JavaScript {
         Register loadName(StringAtom &name);
         Register getProperty(StringAtom &name, Register base);
 
-
-        void beginStatement(const SourcePosition &pos)        { resetTopRegister(); }
+        Register getRegisterBase()                          { return topRegister; }
+        InstructionStream *get_iCode()                      { return iCode; }
 
 
     // Rather than have the ICG client maniplate labels and branches, it
@@ -197,13 +221,16 @@ namespace JavaScript {
     // in the order listed for each construct, (internal error otherwise).
     // The ICG will enforce correct nesting and closing.
 
+        // expression statements
+        void beginStatement(const SourcePosition &pos)      { resetTopRegister(); }
     
+        
         void beginWhileStatement(const SourcePosition &pos);
         void endWhileExpression(Register condition);
         void endWhileStatement();
 
     
-        void beginDoStatement();
+        void beginDoStatement(const SourcePosition &pos);
         void endDoStatement();
         void endDoExpression(Register condition);
 
@@ -220,23 +247,27 @@ namespace JavaScript {
         void endForStatement();
 
 
-        void beginSwitchStatement(Register expression);
+        void beginSwitchStatement(const SourcePosition &pos, Register expression);
 
-        // sequences of the next three follow for each case clause
-        void beginCaseStatement();
         void endCaseCondition(Register expression);
-        void endCaseStatement();             // corresponds to a break and may be omitted
     
+        void beginCaseStatement();
+        void endCaseStatement();
+        
         // optionally
         void beginDefaultStatement();
-        void endDefaultStatement();          // the break for the default clause, may be omitted
+        void endDefaultStatement();
 
         void endSwitchStatement();
 
 
-        void labelStatement(const StringAtom &label);         // adds to label set for next statement, 
-                                                         // removed when that statement is finished
+        void labelStatement(const StringAtom &label);           // adds to label set for next statement, 
+                                                                // removed when that statement is finished
+        void continueStatement();
+        void breakStatement();
+
         void continueStatement(const StringAtom &label);
+        void breakStatement(const StringAtom &label);
 
 
         void throwStatement(Register expression);
@@ -253,5 +284,11 @@ namespace JavaScript {
 
     ostream &operator<<(ostream &s, ICodeGenerator &i);
     ostream &operator<<(ostream &s, StringAtom &str);
+
+    inline ICodeState::ICodeState(StateKind kind, ICodeGenerator *icg) 
+                    : stateKind(kind), breakLabel(-1), continueLabel(-1), registerBase(icg->getRegisterBase()) { }
+
+    inline MultiPathICodeState::MultiPathICodeState(StateKind kind, ICodeGenerator *icg)
+                    : ICodeState(kind, icg), its_iCode(icg->get_iCode()) {}
 }
 #endif

js/js2/js2.cpp

@@ -371,6 +371,37 @@ void testICG(World &world)
         icg.beginElseStatement(false);
         icg.endIfStatement();
 
+
+        // switch (i) { case 3: case 4: j = 4; break; case 5: j = 5; break; default : j = 6; }
+        r1 = icg.loadVariable(0);   
+        icg.beginSwitchStatement(pos, r1);
+            // case 3, note empty case statement (?necessary???)
+            icg.endCaseCondition(icg.loadImmediate(3));
+                icg.beginCaseStatement();
+                icg.endCaseStatement();
+            // case 4
+            icg.endCaseCondition(icg.loadImmediate(4));
+                icg.beginCaseStatement();
+                icg.beginStatement(pos);
+                icg.saveVariable(1, icg.loadImmediate(4));
+                icg.breakStatement();
+                icg.endCaseStatement();
+            // case 5
+            icg.endCaseCondition(icg.loadImmediate(5));
+                icg.beginCaseStatement();
+                icg.beginStatement(pos);
+                icg.saveVariable(1, icg.loadImmediate(5));
+                icg.breakStatement();
+                icg.endCaseStatement();
+            // default
+                icg.beginDefaultStatement();
+                icg.beginStatement(pos);
+                icg.saveVariable(1, icg.loadImmediate(6));
+                icg.endDefaultStatement();
+        icg.endSwitchStatement();
+
+        InstructionStream *iCode = icg.complete();
+
         std::cout << icg;
 }
 
@@ -380,7 +411,7 @@ int main(int argc, char **argv)
     initConsole("\pJavaScript Shell", "Welcome to the js2 shell.\n", argc, argv);
 #endif
 	World world;
-#if 0
+#if 1
         testICG(world);
 #else
 	readEvalPrint(std::cin, world);

js2/src/icodegenerator.cpp

@@ -144,24 +144,37 @@ void ICodeGenerator::setLabel(int32 label)
     l->itsOffset = iCode->size();
 }
 
+void ICodeGenerator::setLabel(InstructionStream *stream, int32 label)
+{
+    Label* l;
+#ifdef __GNUC__
+    // libg++'s vector class doesn't have at():
+    if (label >= labels.size())
+        throw std::out_of_range("label out of range");
+    l = labels[label];
+#else
+    l = labels.at(label);
+#endif
+    l->itsBase = stream;
+    l->itsOffset = stream->size();
+}
+
 /***********************************************************************************************/
 
 void MultiPathICodeState::mergeStream(InstructionStream *mainStream, LabelList &labels)
 {
-    if (itsTopLabel < labels.size()) { 
-            // labels (might) have been allocated in this stream
-            // we need to adjust their position relative to the 
-            // size of the stream we're joining
-        for (LabelList::iterator i = labels.begin() + itsTopLabel; i != labels.end(); i++) {
-            if ((*i)->itsBase == its_iCode) {
-                (*i)->itsBase = mainStream;
-                (*i)->itsOffset += mainStream->size();
-            }
+    // change InstructionStream to be a class that also remembers
+    // if it contains any labels (maybe even remembers the labels
+    // themselves?) in order to avoid running this loop unnecessarily.
+    for (LabelList::iterator i = labels.begin(); i != labels.end(); i++) {
+        if ((*i)->itsBase == its_iCode) {
+            (*i)->itsBase = mainStream;
+            (*i)->itsOffset += mainStream->size();
         }
     }
 
-    for (InstructionIterator i = its_iCode->begin(); i != its_iCode->end(); i++)
-        mainStream->push_back(*i);
+    for (InstructionIterator ii = its_iCode->begin(); ii != its_iCode->end(); ii++)
+        mainStream->push_back(*ii);
 
 }
 
@@ -178,43 +191,176 @@ void ICodeGenerator::beginWhileStatement(const SourcePosition &pos)
     branch(whileConditionTop);
     
     // save off the current stream while we gen code for the condition
-    stitcher.push(new WhileCodeState(iCode, labels.size(), whileConditionTop, whileBlockStart));
+    stitcher.push_back(new WhileCodeState(whileConditionTop, whileBlockStart, this));
 
     iCode = new InstructionStream();
 }
 
 void ICodeGenerator::endWhileExpression(Register condition)
 {
-    WhileCodeState *ics = static_cast<WhileCodeState *>(stitcher.top());
-    ASSERT(ics->stateKind == While_State);
+    WhileCodeState *ics = static_cast<WhileCodeState *>(stitcher.back());
+    ASSERT(ics->stateKind == While_state);
 
-    branchConditional(ics->whileBodyLabel, condition);
+    branchConditional(ics->whileBody, condition);
     resetTopRegister();
     // stash away the condition expression and switch 
     // back to the main stream
     iCode = ics->swapStream(iCode);
-    setLabel(ics->whileBodyLabel);         // mark the start of the while block
+    setLabel(ics->whileBody);         // mark the start of the while block
 }
   
 void ICodeGenerator::endWhileStatement()
 {
     // recover the while stream
-    WhileCodeState *ics = static_cast<WhileCodeState *>(stitcher.top());
-    ASSERT(ics->stateKind == While_State);
-    stitcher.pop();
+    WhileCodeState *ics = static_cast<WhileCodeState *>(stitcher.back());
+    ASSERT(ics->stateKind == While_state);
+    stitcher.pop_back();
 
     // mark the start of the condition code
     // and re-attach it to the main stream
-    setLabel(ics->whileConditionLabel);
+    setLabel(ics->whileCondition);
 
     ics->mergeStream(iCode, labels);
+    if (ics->breakLabel != -1)
+        setLabel(ics->breakLabel);
 
-    delete ics->its_iCode;
     delete ics;
 
     resetTopRegister();
 }
 
+/***********************************************************************************************/
+
+void ICodeGenerator::beginDoStatement(const SourcePosition &pos)
+{
+    resetTopRegister();
+  
+    // mark the top of the loop body
+    // and reserve a label for the condition
+    int32 doBlock = getLabel();
+    int32 doCondition = getLabel();
+    setLabel(doBlock);
+    
+    stitcher.push_back(new DoCodeState(doBlock, doCondition, this));
+
+    iCode = new InstructionStream();
+}
+
+void ICodeGenerator::endDoStatement()
+{
+    DoCodeState *ics = static_cast<DoCodeState *>(stitcher.back());
+    ASSERT(ics->stateKind == Do_state);
+
+    // mark the start of the do conditional
+    setLabel(ics->doCondition);
+
+    resetTopRegister();
+}
+  
+void ICodeGenerator::endDoExpression(Register condition)
+{
+    DoCodeState *ics = static_cast<DoCodeState *>(stitcher.back());
+    ASSERT(ics->stateKind == Do_state);
+    stitcher.pop_back();
+
+    // add branch to top of do block
+    branchConditional(ics->doBody, condition);
+    if (ics->breakLabel != -1)
+        setLabel(ics->breakLabel);
+
+    delete ics;
+
+    resetTopRegister();
+}
+
+/***********************************************************************************************/
+
+void ICodeGenerator::beginSwitchStatement(const SourcePosition &pos, Register expression)
+{
+    // stash the control expression value
+    resetTopRegister();
+    op(MOVE_TO, getRegister(), expression);
+    // build an instruction stream for the case statements, the case
+    // expressions are generated into the main stream directly, the
+    // case statements are then added back in afterwards.
+    InstructionStream *x = new InstructionStream();
+    SwitchCodeState *ics = new SwitchCodeState(expression, this);
+    ics->swapStream(x);
+    stitcher.push_back(ics);
+}
+
+void ICodeGenerator::endCaseCondition(Register expression)
+{
+    SwitchCodeState *ics = static_cast<SwitchCodeState *>(stitcher.back());
+    ASSERT(ics->stateKind == Switch_state);
+
+    int32 caseLabel = getLabel();
+    Register r = op(COMPARE, expression, ics->controlExpression);
+    branchConditional(caseLabel, r);
+
+    setLabel(ics->its_iCode, caseLabel);                // mark the case in the Case Statement stream 
+    resetTopRegister();
+}
+
+void ICodeGenerator::beginCaseStatement()
+{
+    SwitchCodeState *ics = static_cast<SwitchCodeState *>(stitcher.back());
+    ASSERT(ics->stateKind == Switch_state);
+    iCode = ics->swapStream(iCode);                     // switch to Case Statement stream
+}
+
+void ICodeGenerator::endCaseStatement()
+{
+    SwitchCodeState *ics = static_cast<SwitchCodeState *>(stitcher.back());
+    ASSERT(ics->stateKind == Switch_state);             // do more to guarantee correct blocking?
+    iCode = ics->swapStream(iCode);                     // switch back to Case Conditional stream
+    resetTopRegister();
+}
+
+void ICodeGenerator::beginDefaultStatement()
+{
+    SwitchCodeState *ics = static_cast<SwitchCodeState *>(stitcher.back());
+    ASSERT(ics->stateKind == Switch_state);
+    ASSERT(ics->defaultLabel == -1);
+    ics->defaultLabel = getLabel();
+    setLabel(ics->its_iCode, ics->defaultLabel);
+    iCode = ics->swapStream(iCode);                    // switch to Case Statement stream
+}
+
+void ICodeGenerator::endDefaultStatement()
+{
+    SwitchCodeState *ics = static_cast<SwitchCodeState *>(stitcher.back());
+    ASSERT(ics->stateKind == Switch_state);
+    ASSERT(ics->defaultLabel != -1);            // do more to guarantee correct blocking?
+    iCode = ics->swapStream(iCode);             // switch to Case Statement stream
+    resetTopRegister();
+}
+
+void ICodeGenerator::endSwitchStatement()
+{
+    SwitchCodeState *ics = static_cast<SwitchCodeState *>(stitcher.back());
+    ASSERT(ics->stateKind == Switch_state);
+    stitcher.pop_back();
+
+    // ground out the case chain at the default block or fall thru
+    // to the break label
+    if (ics->defaultLabel != -1)       
+        branch(ics->defaultLabel);
+    else {
+        if (ics->breakLabel == -1)
+            ics->breakLabel = getLabel();
+        branch(ics->breakLabel);
+    }
+    
+    // dump all the case statements into the main stream
+    ics->mergeStream(iCode, labels);
+
+    if (ics->breakLabel != -1)
+        setLabel(ics->breakLabel);
+
+    delete ics;
+}
+
 
 /***********************************************************************************************/
 
@@ -222,7 +368,7 @@ void ICodeGenerator::beginIfStatement(const SourcePosition &pos, Register condit
 {
     int32 elseLabel = getLabel();
     
-    stitcher.push(new IfCodeState(elseLabel, -1));
+    stitcher.push_back(new IfCodeState(elseLabel, -1, this));
 
     Register notCond = op(NOT, condition);
     branchConditional(elseLabel, notCond);
@@ -232,8 +378,8 @@ void ICodeGenerator::beginIfStatement(const SourcePosition &pos, Register condit
 
 void ICodeGenerator::beginElseStatement(bool hasElse)
 {
-    IfCodeState *ics = static_cast<IfCodeState *>(stitcher.top());
-    ASSERT(ics->stateKind == If_State);
+    IfCodeState *ics = static_cast<IfCodeState *>(stitcher.back());
+    ASSERT(ics->stateKind == If_state);
 
     if (hasElse) {
         int32 beyondElse = getLabel();
@@ -246,35 +392,54 @@ void ICodeGenerator::beginElseStatement(bool hasElse)
 
 void ICodeGenerator::endIfStatement()
 {
-    IfCodeState *ics = static_cast<IfCodeState *>(stitcher.top());
-    ASSERT(ics->stateKind == If_State);
+    IfCodeState *ics = static_cast<IfCodeState *>(stitcher.back());
+    ASSERT(ics->stateKind == If_state);
+    stitcher.pop_back();
 
     if (ics->beyondElse != -1) {     // had an else
         setLabel(ics->beyondElse);   // the beyond else label
     }
-    stitcher.pop();
+    
+    delete ics;
     resetTopRegister();
 }
 
+/***********************************************************************************************/
+
+void ICodeGenerator::breakStatement()
+{
+    for (std::vector<ICodeState *>::reverse_iterator p = stitcher.rbegin(); p != stitcher.rend(); p++) {
+        
+// this is NOT going to stay this way
+        
+        if (((*p)->stateKind == While_state)
+                || ((*p)->stateKind == Do_state)
+                || ((*p)->stateKind == For_state)
+                || ((*p)->stateKind == Switch_state)) {
+            if ((*p)->breakLabel == -1)
+                (*p)->breakLabel = getLabel();
+            branch((*p)->breakLabel);
+            return;
+        }
+    }
+    NOT_REACHED("no break target available");
+}
 
 /***********************************************************************************************/
 
 
 char *opcodeName[] = {
+        "move_to",
         "load_var",
         "save_var",
-
         "load_imm",
-
         "load_name",
         "save_name",
-
         "get_prop",
         "set_prop", 
-
         "add",
+        "compare",
         "not",
-
         "branch",
         "branch_cond",
 };
@@ -330,11 +495,13 @@ ostream &ICodeGenerator::print(ostream &s)
                 }
                 break;
             case ADD :
+            case COMPARE :
                 {
                      Instruction_3<Register, Register, Register> *t = static_cast<Instruction_3<Register, Register, Register> * >(instr);
                      s << "R" << t->itsOperand1 << ", R" << t->itsOperand2 << ", R" << t->itsOperand3;
                 }
                 break;
+            case MOVE_TO :
             case NOT :
                 {
                      Instruction_3<Register, Register, Register> *t = static_cast<Instruction_3<Register, Register, Register> * >(instr);

js2/src/icodegenerator.h

@@ -34,6 +34,8 @@ namespace JavaScript {
     enum ICodeOp {
                         //      Operand1                Operand2                Operand3
 
+        MOVE_TO,        // Source Register          Destination Register
+
         LOAD_VAR,       // index of frame slot      Destination Register
         SAVE_VAR,       // index of frame slot      Source Register
 
@@ -46,6 +48,7 @@ namespace JavaScript {
         SET_PROP,       // StringAtom &             Base Register               Source Register
 
         ADD,            // Source Register 1        Source Register 2           Destination Register
+        COMPARE,        // Source Register 1        Source Register 2           Destination Register
         NOT,            // Source Register          Destination Register
 
         BRANCH,         // Target label
@@ -104,46 +107,66 @@ namespace JavaScript {
     /****************************************************************/
     /****************************************************************/
 
-    enum StateKind { While_State, If_State };
+    class ICodeGenerator;   // forward declaration
 
-    class ICodeState { 
+    enum StateKind { While_state, If_state, Do_state, Switch_state, For_state };
+
+    class ICodeState {
     public :
-        ICodeState(StateKind kind) : stateKind(kind) { }
+        ICodeState(StateKind kind, ICodeGenerator *icg);        // inline below
         StateKind stateKind;
+        int32 breakLabel;
+        int32 continueLabel;
+        int32 registerBase;
     };
 
     // an ICodeState that handles switching to a new InstructionStream 
     // and then re-combining the streams later
     class MultiPathICodeState : public ICodeState {
     public:
-        MultiPathICodeState(StateKind kind,InstructionStream *iCode, int32 topLabel)
-                            : ICodeState(kind), its_iCode(iCode), itsTopLabel(topLabel) {}
+        MultiPathICodeState(StateKind kind, ICodeGenerator *icg);        // inline below
+        virtual ~MultiPathICodeState()  { delete its_iCode; }
 
         InstructionStream *swapStream(InstructionStream *iCode) { InstructionStream *t = its_iCode; its_iCode = iCode; return t; }
 
         InstructionStream *its_iCode;
-        int32 itsTopLabel;      // set to the highest label allocated when this stream
-                                // was created. If that value changes, this stream may
-                                // contain labels that will need to be adjusted when
-                                // the streams are merged.
+
         void mergeStream(InstructionStream *mainStream, LabelList &labels);
     };
 
     class WhileCodeState : public MultiPathICodeState {
     public:
-        WhileCodeState(InstructionStream *iCode, int32 topLabel, int32 a, int32 b) 
-                    : MultiPathICodeState(While_State, iCode, topLabel), whileConditionLabel(a), whileBodyLabel(b) { }
-        int32 whileConditionLabel;
-        int32 whileBodyLabel;
+        WhileCodeState(int32 conditionLabel, int32 bodyLabel, ICodeGenerator *icg) 
+                    : MultiPathICodeState(While_state, icg), whileCondition(conditionLabel), whileBody(bodyLabel) { }
+        int32 whileCondition;
+        int32 whileBody;
     };
 
     class IfCodeState : public ICodeState {
     public:
-        IfCodeState(int32 a, int32 b) : ICodeState(If_State), elseLabel(a), beyondElse(b) { }
+        IfCodeState(int32 a, int32 b, ICodeGenerator *icg) 
+                    : ICodeState(If_state, icg), elseLabel(a), beyondElse(b) { }
         int32 elseLabel;
         int32 beyondElse;
     };
 
+    class DoCodeState : public ICodeState {
+    public:
+        DoCodeState(int32 bodyLabel, int32 conditionLabel, ICodeGenerator *icg) 
+                    : ICodeState(Do_state, icg), doBody(bodyLabel), doCondition(conditionLabel) { }
+        int32 doBody;
+        int32 doCondition;
+    };
+
+    class SwitchCodeState : public MultiPathICodeState {
+    public:
+        SwitchCodeState(Register control, ICodeGenerator *icg) 
+                    : MultiPathICodeState(Switch_state, icg), controlExpression(control), defaultLabel(-1) { }
+        
+        Register controlExpression;
+        int32 defaultLabel;
+    };
+
     /****************************************************************/
         
     // An ICodeGenerator provides the interface between the parser and the interpreter.
@@ -157,20 +180,21 @@ namespace JavaScript {
         
         LabelList labels;
 
-        std::stack<ICodeState *> stitcher;
+        std::vector<ICodeState *> stitcher;
 
         Register topRegister;
         Register getRegister()      { return topRegister++; }
-        void resetTopRegister()     { topRegister = 0; }
+        void resetTopRegister()     { topRegister = stitcher.empty() ? 0 : stitcher.back()->registerBase; }
 
         int32 getLabel();
         void setLabel(int32 label);
+        void setLabel(InstructionStream *stream, int32 label);
 
         void branch(int32 label);
         void branchConditional(int32 label, Register condition);
     
     public:
-        ICodeGenerator() { iCode = new InstructionStream(); }
+        ICodeGenerator() : topRegister(0) { iCode = new InstructionStream(); }
 
         InstructionStream *complete();
 
@@ -187,8 +211,8 @@ namespace JavaScript {
         Register loadName(StringAtom &name);
         Register getProperty(StringAtom &name, Register base);
 
-
-        void beginStatement(const SourcePosition &pos)        { resetTopRegister(); }
+        Register getRegisterBase()                          { return topRegister; }
+        InstructionStream *get_iCode()                      { return iCode; }
 
 
     // Rather than have the ICG client maniplate labels and branches, it
@@ -197,13 +221,16 @@ namespace JavaScript {
     // in the order listed for each construct, (internal error otherwise).
     // The ICG will enforce correct nesting and closing.
 
+        // expression statements
+        void beginStatement(const SourcePosition &pos)      { resetTopRegister(); }
     
+        
         void beginWhileStatement(const SourcePosition &pos);
         void endWhileExpression(Register condition);
         void endWhileStatement();
 
     
-        void beginDoStatement();
+        void beginDoStatement(const SourcePosition &pos);
         void endDoStatement();
         void endDoExpression(Register condition);
 
@@ -220,23 +247,27 @@ namespace JavaScript {
         void endForStatement();
 
 
-        void beginSwitchStatement(Register expression);
+        void beginSwitchStatement(const SourcePosition &pos, Register expression);
 
-        // sequences of the next three follow for each case clause
-        void beginCaseStatement();
         void endCaseCondition(Register expression);
-        void endCaseStatement();             // corresponds to a break and may be omitted
     
+        void beginCaseStatement();
+        void endCaseStatement();
+        
         // optionally
         void beginDefaultStatement();
-        void endDefaultStatement();          // the break for the default clause, may be omitted
+        void endDefaultStatement();
 
         void endSwitchStatement();
 
 
-        void labelStatement(const StringAtom &label);         // adds to label set for next statement, 
-                                                         // removed when that statement is finished
+        void labelStatement(const StringAtom &label);           // adds to label set for next statement, 
+                                                                // removed when that statement is finished
+        void continueStatement();
+        void breakStatement();
+
         void continueStatement(const StringAtom &label);
+        void breakStatement(const StringAtom &label);
 
 
         void throwStatement(Register expression);
@@ -253,5 +284,11 @@ namespace JavaScript {
 
     ostream &operator<<(ostream &s, ICodeGenerator &i);
     ostream &operator<<(ostream &s, StringAtom &str);
+
+    inline ICodeState::ICodeState(StateKind kind, ICodeGenerator *icg) 
+                    : stateKind(kind), breakLabel(-1), continueLabel(-1), registerBase(icg->getRegisterBase()) { }
+
+    inline MultiPathICodeState::MultiPathICodeState(StateKind kind, ICodeGenerator *icg)
+                    : ICodeState(kind, icg), its_iCode(icg->get_iCode()) {}
 }
 #endif

js2/tests/cpp/js2_shell.cpp

@@ -371,6 +371,37 @@ void testICG(World &world)
         icg.beginElseStatement(false);
         icg.endIfStatement();
 
+
+        // switch (i) { case 3: case 4: j = 4; break; case 5: j = 5; break; default : j = 6; }
+        r1 = icg.loadVariable(0);   
+        icg.beginSwitchStatement(pos, r1);
+            // case 3, note empty case statement (?necessary???)
+            icg.endCaseCondition(icg.loadImmediate(3));
+                icg.beginCaseStatement();
+                icg.endCaseStatement();
+            // case 4
+            icg.endCaseCondition(icg.loadImmediate(4));
+                icg.beginCaseStatement();
+                icg.beginStatement(pos);
+                icg.saveVariable(1, icg.loadImmediate(4));
+                icg.breakStatement();
+                icg.endCaseStatement();
+            // case 5
+            icg.endCaseCondition(icg.loadImmediate(5));
+                icg.beginCaseStatement();
+                icg.beginStatement(pos);
+                icg.saveVariable(1, icg.loadImmediate(5));
+                icg.breakStatement();
+                icg.endCaseStatement();
+            // default
+                icg.beginDefaultStatement();
+                icg.beginStatement(pos);
+                icg.saveVariable(1, icg.loadImmediate(6));
+                icg.endDefaultStatement();
+        icg.endSwitchStatement();
+
+        InstructionStream *iCode = icg.complete();
+
         std::cout << icg;
 }
 
@@ -380,7 +411,7 @@ int main(int argc, char **argv)
     initConsole("\pJavaScript Shell", "Welcome to the js2 shell.\n", argc, argv);
 #endif
 	World world;
-#if 0
+#if 1
         testICG(world);
 #else
 	readEvalPrint(std::cin, world);