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// Copyright (c) 1996 David Engberg All rights reserved
// $Id: CodeSequence.h,v 1.4 1996/07/12 20:43:40 geppetto Exp $
#ifndef _CodeSequence_h
#define _CodeSequence_h
#pragma interface
#include "JavaCodeAttribute.h"
#include <deque>
#include <vector>
class ostream;
//
// Class name : CCodeSequence
// Description : This class encapsulates a sequence of Java instructions under
// construction.
//
class CCodeSequence {
public:
CCodeSequence();
CCodeSequence(const CCodeSequence& source);
~CCodeSequence();
CCodeSequence& operator=(const CCodeSequence& source);
//
// Struct name : CInstruction
// Description : This structure represents one instruction in the Java byte
// code sequence, along with any arguments it has. It is meant to be
// small (8 bytes) and dumb to make it fast to copy and modify.
// As such, it doesn't present a very OO interface. This is an
// intentional optimization, the alternative would rely on huge,
// heap-allocated polymorphism, which would be serious overkill for
// the job.
//
struct Instruction {
CJavaCodeAttribute::Opcode fOpcode;
union {
unsigned long u4;
unsigned long l4;
signed short s2;
signed char s1;
struct {
unsigned short index : 16;
unsigned char u1 : 8;
} fIndexPair;
} fArguments;
};
typedef vector<Instruction> InstructionList;
typedef vector<unsigned long> OffsetList;
unsigned long size() const { return fInstructions.size(); }
Instruction& operator[](unsigned long index) { return fInstructions[index]; }
const Instruction& operator[](unsigned long index) const
{ return fInstructions[index]; }
InstructionList::const_iterator GetInstructionsBegin() const;
InstructionList::const_iterator GetInstructionsEnd() const;
void Insert(unsigned long index, const Instruction& value);
void Append(const Instruction& value, unsigned long lineNumber = 0);
void Append(CJavaCodeAttribute::Opcode opcode, unsigned long lineNumber = 0);
void Append(CJavaCodeAttribute::Opcode opcode, unsigned long u4,
unsigned long lineNumber);
void Remove(unsigned long index);
void Remove(unsigned long index, unsigned long count);
unsigned long CreateBlockLabel();
// unsigned long PeekNextBlockLabel() const;
unsigned long LabelToInstruction(unsigned long blockLabelIndex) const;
bool InstructionToLabel(unsigned long blockLabelIndex,
unsigned long& label) const;
void PeepholeOptimize();
void EliminateDeadCode(CJavaCodeAttribute& inCodeAttribute);
void Finalize(CJavaCodeAttribute& intoCodeAttribute);
void PrintShortDebug(ostream& toStream) const;
protected:
unsigned long FinalizeInstruction(unsigned long instructionIndex,
const OffsetList& offsetLabels);
unsigned long InstructionSize(unsigned long instructionIndex,
unsigned long startingAtPosition) const;
void EmitCode(unsigned long instruction, unsigned long instructionLocation,
const OffsetList& offsetLabels,
CJavaCodeAttribute& into) const;
void AppendIndex(unsigned long instruction, CJavaCodeAttribute& onto) const;
unsigned long MatchRange(const CJavaCodeAttribute::Opcode pattern[],
unsigned long patternLength,
unsigned long startingAt,
bool crossBasicBlocks = false);
bool ReplaceIncrement(unsigned long startingAt);
bool ReplaceZeroCompare(unsigned long startingAt);
bool ReplaceBooleanBranch(unsigned long startingAt);
bool ReplaceBranchToBranch(unsigned long startingAt);
void CreateBlockIfConditional(CJavaCodeAttribute::Opcode instruction);
void MarkReachableFrom(unsigned long index, bool reachable[]);
private:
void PrintInstruction(const Instruction& instruction,
ostream& toStream) const;
InstructionList fInstructions;
OffsetList fBasicBlockOffsets;
unsigned long fLastBasicBlock;
vector<unsigned long> fLineNumbers;
OffsetList fLineBeginnings;
unsigned long fLastLine;
};
#endif
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