gecko-dev/js/js2/icodegenerator.cpp

// -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
//
// The contents of this file are subject to the Netscape Public
// License Version 1.1 (the "License"); you may not use this file
// except in compliance with the License. You may obtain a copy of
// the License at http://www.mozilla.org/NPL/
//
// Software distributed under the License is distributed on an "AS
// IS" basis, WITHOUT WARRANTY OF ANY KIND, either express oqr
// implied. See the License for the specific language governing
// rights and limitations under the License.
//
// The Original Code is the JavaScript 2 Prototype.
//
// The Initial Developer of the Original Code is Netscape
// Communications Corporation.  Portions created by Netscape are
// Copyright (C) 1998 Netscape Communications Corporation. All
// Rights Reserved.

#include "numerics.h"
#include "world.h"
#include "utilities.h"
#include "icodegenerator.h"

#include <iomanip>
#include <stdexcept>

namespace JS = JavaScript;
using namespace JavaScript;

ostream &JS::operator<<(ostream &s, ICodeGenerator &i)
{
    return i.print(s);
}

//
// ICodeGenerator
//

InstructionStream *ICodeGenerator::complete()
{
#ifdef DEBUG
    ASSERT(stitcher.empty());
    for (LabelIterator i = labels.begin(); i != labels.end(); i++) {
        ASSERT((*i)->itsBase == iCode);
        ASSERT((*i)->itsOffset >= 0);
        ASSERT((*i)->itsOffset < iCode->size());
    }
#endif            
    return iCode;
}


/***********************************************************************************************/

Register ICodeGenerator::loadVariable(int32 frameIndex)
{
    Register dest = getRegister();
    Instruction_2<int32, Register> *instr = new Instruction_2<int32, Register>(LOAD_VAR, frameIndex, dest);
    iCode->push_back(instr);
    return dest;
}

Register ICodeGenerator::loadImmediate(double value)
{
    Register dest = getRegister();
    Instruction_2<double, Register> *instr = new Instruction_2<double, Register>(LOAD_IMMEDIATE, value, dest);
    iCode->push_back(instr);
    return dest;
}

Register ICodeGenerator::loadName(StringAtom &name)
{
    Register dest = getRegister();
    Instruction_2<StringAtom &, Register> *instr = new Instruction_2<StringAtom &, Register>(LOAD_NAME, name, dest);
    iCode->push_back(instr);
    return dest;
}

Register ICodeGenerator::getProperty(StringAtom &name, Register base)
{
    Register dest = getRegister();
    Instruction_3<StringAtom &, Register, Register> *instr = new Instruction_3<StringAtom &, Register, Register>(GET_PROP, name, base, dest);
    iCode->push_back(instr);
    return dest;
}

void ICodeGenerator::saveVariable(int32 frameIndex, Register value)
{
    Instruction_2<int32, Register> *instr = new Instruction_2<int32, Register>(SAVE_VAR, frameIndex, value);
    iCode->push_back(instr);
}

Register ICodeGenerator::op(ICodeOp op, Register source)
{
    Register dest = getRegister();
    Instruction_2<Register, Register> *instr = new Instruction_2<Register, Register>(op, source, dest);
    iCode->push_back(instr);
    return dest;
}

Register ICodeGenerator::op(ICodeOp op, Register source1, Register source2)
{
    Register dest = getRegister();
    Instruction_3<Register, Register, Register> *instr = new Instruction_3<Register, Register, Register>(op, source1, source2, dest);
    iCode->push_back(instr);
    return dest;
}

void ICodeGenerator::branch(int32 label)
{
    Instruction_1<int32> *instr = new Instruction_1<int32>(BRANCH, label);
    iCode->push_back(instr);
}

void ICodeGenerator::branchConditional(int32 label, Register condition)
{
    Instruction_2<int32, Register> *instr = new Instruction_2<int32, Register>(BRANCH_COND, label, condition);
    iCode->push_back(instr);
}


/***********************************************************************************************/

int32 ICodeGenerator::getLabel()
{
    int32 result = labels.size();
    labels.push_back(new Label(NULL, -1));
    return result;
}

void ICodeGenerator::setLabel(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 = iCode;
    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)
{
    // 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 ii = its_iCode->begin(); ii != its_iCode->end(); ii++)
        mainStream->push_back(*ii);

}

/***********************************************************************************************/

void ICodeGenerator::beginWhileStatement(const SourcePosition &pos)
{
    resetTopRegister();
  
    // insert a branch to the while condition, which we're 
    // moving to follow the while block
    int32 whileConditionTop = getLabel();
    int32 whileBlockStart = getLabel();
    branch(whileConditionTop);
    
    // save off the current stream while we gen code for the condition
    stitcher.push_back(new WhileCodeState(whileConditionTop, whileBlockStart, this));

    iCode = new InstructionStream();
}

void ICodeGenerator::endWhileExpression(Register condition)
{
    WhileCodeState *ics = static_cast<WhileCodeState *>(stitcher.back());
    ASSERT(ics->stateKind == While_state);

    branchConditional(ics->whileBody, condition);
    resetTopRegister();
    // stash away the condition expression and switch 
    // back to the main stream
    iCode = ics->swapStream(iCode);
    setLabel(ics->whileBody);         // mark the start of the while block
}
  
void ICodeGenerator::endWhileStatement()
{
    // recover the while stream
    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->whileCondition);

    ics->mergeStream(iCode, labels);
    if (ics->breakLabel != -1)
        setLabel(ics->breakLabel);

    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;
}


/***********************************************************************************************/

void ICodeGenerator::beginIfStatement(const SourcePosition &pos, Register condition)
{
    int32 elseLabel = getLabel();
    
    stitcher.push_back(new IfCodeState(elseLabel, -1, this));

    Register notCond = op(NOT, condition);
    branchConditional(elseLabel, notCond);

    resetTopRegister();
}

void ICodeGenerator::beginElseStatement(bool hasElse)
{
    IfCodeState *ics = static_cast<IfCodeState *>(stitcher.back());
    ASSERT(ics->stateKind == If_state);

    if (hasElse) {
        int32 beyondElse = getLabel();
        ics->beyondElse = beyondElse;
        branch(beyondElse);
    }
    setLabel(ics->elseLabel);
    resetTopRegister();
}

void ICodeGenerator::endIfStatement()
{
    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
    }
    
    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",
};

ostream &JS::operator<<(ostream &s, StringAtom &str)
{
    for (String::iterator i = str.begin(); i != str.end(); i++)
        s << (char)*i;
    return s;
}

ostream &ICodeGenerator::print(ostream &s)
{
    s << "ICG! " << iCode->size() << "\n";
    for (InstructionIterator i = iCode->begin(); i != iCode->end(); i++) {
        for (LabelList::iterator k = labels.begin(); k != labels.end(); k++)
            if ((*k)->itsOffset == (i - iCode->begin())) {
                s << "label #" << (k - labels.begin()) << ":\n";
            }
        
        Instruction *instr = *i;
        s << "\t"<< std::setiosflags( std::ostream::left ) << std::setw(16) << opcodeName[instr->itsOp];
        switch (instr->itsOp) {
            case LOAD_NAME :
                {
                    Instruction_2<StringAtom &, Register> *t = static_cast<Instruction_2<StringAtom &, Register> * >(instr);
                    s << "\"" << t->itsOperand1 <<  "\", R" << t->itsOperand2;
                }
                break;
            case LOAD_IMMEDIATE :
                {
                    Instruction_2<double, Register> *t = static_cast<Instruction_2<double, Register> * >(instr);
                    s << t->itsOperand1 << ", R" << t->itsOperand2;
                }
                break;
            case LOAD_VAR :
            case SAVE_VAR :
                {
                    Instruction_2<int, Register> *t = static_cast<Instruction_2<int, Register> * >(instr);
                    s << "Variable #" << t->itsOperand1 << ", R" << t->itsOperand2;
                }
                break;
            case BRANCH :
                {
                    Instruction_1<int32> *t = static_cast<Instruction_1<int32> * >(instr);
                    s << "target #" << t->itsOperand1;
                }
                break;
            case BRANCH_COND :
                {
                    Instruction_2<int32, Register> *t = static_cast<Instruction_2<int32, Register> * >(instr);
                    s << "target #" << t->itsOperand1 << ", R" << t->itsOperand2;
                }
                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);
                     s << "R" << t->itsOperand1 << ", R" << t->itsOperand2;
                }
                break;
        }
        s << "\n";
    }
    for (LabelList::iterator k = labels.begin(); k != labels.end(); k++)
        if ((*k)->itsOffset == (iCode->end() - iCode->begin())) {
            s << "label #" << (k - labels.begin()) << ":\n";
        }
    return s;
}