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llvm-6502/lib/Bytecode/Reader/InstructionReader.cpp

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//===- ReadInst.cpp - Code to read an instruction from bytecode -----------===//
//
// This file defines the mechanism to read an instruction from a bytecode
// stream.
//
// Note that this library should be as fast as possible, reentrant, and
// threadsafe!!
//
//===----------------------------------------------------------------------===//
#include "ReaderInternals.h"
#include "llvm/iTerminators.h"
#include "llvm/iMemory.h"
#include "llvm/iPHINode.h"
#include "llvm/iOther.h"
#include "llvm/Module.h"
namespace {
struct RawInst { // The raw fields out of the bytecode stream...
unsigned NumOperands;
unsigned Opcode;
unsigned Type;
RawInst(const unsigned char *&Buf, const unsigned char *EndBuf,
std::vector<unsigned> &Args);
};
}
RawInst::RawInst(const unsigned char *&Buf, const unsigned char *EndBuf,
std::vector<unsigned> &Args) {
unsigned Op, Typ;
if (read(Buf, EndBuf, Op))
throw std::string("Error reading from buffer.");
// bits Instruction format: Common to all formats
// --------------------------
// 01-00: Opcode type, fixed to 1.
// 07-02: Opcode
Opcode = (Op >> 2) & 63;
Args.resize((Op >> 0) & 03);
switch (Args.size()) {
case 1:
// bits Instruction format:
// --------------------------
// 19-08: Resulting type plane
// 31-20: Operand #1 (if set to (2^12-1), then zero operands)
//
Type = (Op >> 8) & 4095;
Args[0] = (Op >> 20) & 4095;
if (Args[0] == 4095) // Handle special encoding for 0 operands...
Args.resize(0);
break;
case 2:
// bits Instruction format:
// --------------------------
// 15-08: Resulting type plane
// 23-16: Operand #1
// 31-24: Operand #2
//
Type = (Op >> 8) & 255;
Args[0] = (Op >> 16) & 255;
Args[1] = (Op >> 24) & 255;
break;
case 3:
// bits Instruction format:
// --------------------------
// 13-08: Resulting type plane
// 19-14: Operand #1
// 25-20: Operand #2
// 31-26: Operand #3
//
Type = (Op >> 8) & 63;
Args[0] = (Op >> 14) & 63;
Args[1] = (Op >> 20) & 63;
Args[2] = (Op >> 26) & 63;
break;
case 0:
Buf -= 4; // Hrm, try this again...
if (read_vbr(Buf, EndBuf, Opcode))
throw std::string("Error reading from buffer.");
Opcode >>= 2;
if (read_vbr(Buf, EndBuf, Type))
throw std::string("Error reading from buffer.");
unsigned NumOperands;
if (read_vbr(Buf, EndBuf, NumOperands))
throw std::string("Error reading from buffer.");
Args.resize(NumOperands);
if (NumOperands == 0)
throw std::string("Zero-argument instruction found; this is invalid.");
for (unsigned i = 0; i != NumOperands; ++i)
if (read_vbr(Buf, EndBuf, Args[i]))
throw std::string("Error reading from buffer");
if (align32(Buf, EndBuf))
throw std::string("Unaligned bytecode buffer.");
break;
}
}
void BytecodeParser::ParseInstruction(const unsigned char *&Buf,
const unsigned char *EndBuf,
std::vector<unsigned> &Args,
BasicBlock *BB) {
Args.clear();
RawInst RI(Buf, EndBuf, Args);
const Type *InstTy = getType(RI.Type);
Instruction *Result = 0;
if (RI.Opcode >= Instruction::BinaryOpsBegin &&
RI.Opcode < Instruction::BinaryOpsEnd && Args.size() == 2)
Result = BinaryOperator::create((Instruction::BinaryOps)RI.Opcode,
getValue(RI.Type, Args[0]),
getValue(RI.Type, Args[1]));
switch (RI.Opcode) {
default:
if (Result == 0) throw std::string("Illegal instruction read!");
break;
case Instruction::VAArg:
Result = new VAArgInst(getValue(RI.Type, Args[0]), getType(Args[1]));
break;
case Instruction::VANext:
if (!hasOldStyleVarargs) {
Result = new VANextInst(getValue(RI.Type, Args[0]), getType(Args[1]));
} else {
// In the old-style varargs scheme, this was the "va_arg" instruction.
// Emit emulation code now.
if (!usesOldStyleVarargs) {
usesOldStyleVarargs = true;
std::cerr << "WARNING: this bytecode file uses obsolete features. "
<< "Disassemble and assemble to update it.\n";
}
Value *VAListPtr = getValue(RI.Type, Args[0]);
const Type *ArgTy = getType(Args[1]);
// First, load the valist...
Instruction *CurVAList = new LoadInst(VAListPtr, "");
BB->getInstList().push_back(CurVAList);
// Construct the vaarg
Result = new VAArgInst(CurVAList, ArgTy);
// Now we must advance the pointer and update it in memory.
Instruction *TheVANext = new VANextInst(CurVAList, ArgTy);
BB->getInstList().push_back(TheVANext);
BB->getInstList().push_back(new StoreInst(TheVANext, VAListPtr));
}
break;
case Instruction::Cast:
Result = new CastInst(getValue(RI.Type, Args[0]), getType(Args[1]));
break;
case Instruction::PHI: {
if (Args.size() == 0 || (Args.size() & 1))
throw std::string("Invalid phi node encountered!\n");
PHINode *PN = new PHINode(InstTy);
PN->op_reserve(Args.size());
for (unsigned i = 0, e = Args.size(); i != e; i += 2)
PN->addIncoming(getValue(RI.Type, Args[i]), getBasicBlock(Args[i+1]));
Result = PN;
break;
}
case Instruction::Shl:
case Instruction::Shr:
Result = new ShiftInst((Instruction::OtherOps)RI.Opcode,
getValue(RI.Type, Args[0]),
getValue(Type::UByteTyID, Args[1]));
break;
case Instruction::Ret:
if (Args.size() == 0)
Result = new ReturnInst();
else if (Args.size() == 1)
Result = new ReturnInst(getValue(RI.Type, Args[0]));
else
throw std::string("Unrecognized instruction!");
break;
case Instruction::Br:
if (Args.size() == 1)
Result = new BranchInst(getBasicBlock(Args[0]));
else if (Args.size() == 3)
Result = new BranchInst(getBasicBlock(Args[0]), getBasicBlock(Args[1]),
getValue(Type::BoolTyID , Args[2]));
else
throw std::string("Invalid number of operands for a 'br' instruction!");
break;
case Instruction::Switch: {
if (Args.size() & 1)
throw std::string("Switch statement with odd number of arguments!");
SwitchInst *I = new SwitchInst(getValue(RI.Type, Args[0]),
getBasicBlock(Args[1]));
for (unsigned i = 2, e = Args.size(); i != e; i += 2)
I->addCase(cast<Constant>(getValue(RI.Type, Args[i])),
getBasicBlock(Args[i+1]));
Result = I;
break;
}
case Instruction::Call: {
if (Args.size() == 0)
throw std::string("Invalid call instruction encountered!");
Value *F = getValue(RI.Type, Args[0]);
// Check to make sure we have a pointer to function type
const PointerType *PTy = dyn_cast<PointerType>(F->getType());
if (PTy == 0) throw std::string("Call to non function pointer value!");
const FunctionType *FTy = dyn_cast<FunctionType>(PTy->getElementType());
if (FTy == 0) throw std::string("Call to non function pointer value!");
std::vector<Value *> Params;
const FunctionType::ParamTypes &PL = FTy->getParamTypes();
if (!FTy->isVarArg()) {
FunctionType::ParamTypes::const_iterator It = PL.begin();
for (unsigned i = 1, e = Args.size(); i != e; ++i) {
if (It == PL.end()) throw std::string("Invalid call instruction!");
Params.push_back(getValue(*It++, Args[i]));
}
if (It != PL.end()) throw std::string("Invalid call instruction!");
} else {
Args.erase(Args.begin(), Args.begin()+1+hasVarArgCallPadding);
unsigned FirstVariableOperand;
if (!hasVarArgCallPadding) {
if (Args.size() < FTy->getNumParams())
throw std::string("Call instruction missing operands!");
// Read all of the fixed arguments
for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
Params.push_back(getValue(FTy->getParamType(i), Args[i]));
FirstVariableOperand = FTy->getNumParams();
} else {
FirstVariableOperand = 0;
}
if ((Args.size()-FirstVariableOperand) & 1) // Must be pairs of type/value
throw std::string("Invalid call instruction!");
for (unsigned i = FirstVariableOperand, e = Args.size(); i != e; i += 2)
Params.push_back(getValue(Args[i], Args[i+1]));
}
Result = new CallInst(F, Params);
break;
}
case Instruction::Invoke: {
if (Args.size() < 3) throw std::string("Invalid invoke instruction!");
Value *F = getValue(RI.Type, Args[0]);
// Check to make sure we have a pointer to function type
const PointerType *PTy = dyn_cast<PointerType>(F->getType());
if (PTy == 0) throw std::string("Invoke to non function pointer value!");
const FunctionType *FTy = dyn_cast<FunctionType>(PTy->getElementType());
if (FTy == 0) throw std::string("Invoke to non function pointer value!");
std::vector<Value *> Params;
BasicBlock *Normal, *Except;
const FunctionType::ParamTypes &PL = FTy->getParamTypes();
if (!FTy->isVarArg()) {
Normal = getBasicBlock(Args[1]);
Except = getBasicBlock(Args[2]);
FunctionType::ParamTypes::const_iterator It = PL.begin();
for (unsigned i = 3, e = Args.size(); i != e; ++i) {
if (It == PL.end()) throw std::string("Invalid invoke instruction!");
Params.push_back(getValue(*It++, Args[i]));
}
if (It != PL.end()) throw std::string("Invalid invoke instruction!");
} else {
Args.erase(Args.begin(), Args.begin()+1+hasVarArgCallPadding);
unsigned FirstVariableArgument;
if (!hasVarArgCallPadding) {
Normal = getBasicBlock(Args[0]);
Except = getBasicBlock(Args[1]);
FirstVariableArgument = FTy->getNumParams()+2;
for (unsigned i = 2; i != FirstVariableArgument; ++i)
Params.push_back(getValue(FTy->getParamType(i-2), Args[i]));
} else {
if (Args.size() < 4) throw std::string("Invalid invoke instruction!");
if (Args[0] != Type::LabelTyID || Args[2] != Type::LabelTyID)
throw std::string("Invalid invoke instruction!");
Normal = getBasicBlock(Args[1]);
Except = getBasicBlock(Args[3]);
FirstVariableArgument = 4;
}
if (Args.size()-FirstVariableArgument & 1) // Must be pairs of type/value
throw std::string("Invalid invoke instruction!");
for (unsigned i = FirstVariableArgument; i < Args.size(); i += 2)
Params.push_back(getValue(Args[i], Args[i+1]));
}
Result = new InvokeInst(F, Normal, Except, Params);
break;
}
case Instruction::Malloc:
if (Args.size() > 2) throw std::string("Invalid malloc instruction!");
if (!isa<PointerType>(InstTy))
throw std::string("Invalid malloc instruction!");
Result = new MallocInst(cast<PointerType>(InstTy)->getElementType(),
Args.size() ? getValue(Type::UIntTyID,
Args[0]) : 0);
break;
case Instruction::Alloca:
if (Args.size() > 2) throw std::string("Invalid alloca instruction!");
if (!isa<PointerType>(InstTy))
throw std::string("Invalid alloca instruction!");
Result = new AllocaInst(cast<PointerType>(InstTy)->getElementType(),
Args.size() ? getValue(Type::UIntTyID, Args[0]) :0);
break;
case Instruction::Free:
if (!isa<PointerType>(InstTy))
throw std::string("Invalid free instruction!");
Result = new FreeInst(getValue(RI.Type, Args[0]));
break;
case Instruction::GetElementPtr: {
if (Args.size() == 0 || !isa<PointerType>(InstTy))
throw std::string("Invalid getelementptr instruction!");
std::vector<Value*> Idx;
const Type *NextTy = InstTy;
for (unsigned i = 1, e = Args.size(); i != e; ++i) {
const CompositeType *TopTy = dyn_cast_or_null<CompositeType>(NextTy);
if (!TopTy) throw std::string("Invalid getelementptr instruction!");
Idx.push_back(getValue(TopTy->getIndexType(), Args[i]));
NextTy = GetElementPtrInst::getIndexedType(InstTy, Idx, true);
}
Result = new GetElementPtrInst(getValue(RI.Type, Args[0]), Idx);
break;
}
case 62: // volatile load
case Instruction::Load:
if (Args.size() != 1 || !isa<PointerType>(InstTy))
throw std::string("Invalid load instruction!");
Result = new LoadInst(getValue(RI.Type, Args[0]), "", RI.Opcode == 62);
break;
case 63: // volatile store
case Instruction::Store: {
if (!isa<PointerType>(InstTy) || Args.size() != 2)
throw std::string("Invalid store instruction!");
Value *Ptr = getValue(RI.Type, Args[1]);
const Type *ValTy = cast<PointerType>(Ptr->getType())->getElementType();
Result = new StoreInst(getValue(ValTy, Args[0]), Ptr, RI.Opcode == 63);
break;
}
case Instruction::Unwind:
if (Args.size() != 0) throw std::string("Invalid unwind instruction!");
Result = new UnwindInst();
break;
} // end switch(RI.Opcode)
insertValue(Result, Values);
BB->getInstList().push_back(Result);
BCR_TRACE(4, *Result);
}
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