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llvm-mirror/lib/Bytecode/Writer/InstructionWriter.cpp
Chris Lattner ada730740b Implement support for a new LLVM 1.3 bytecode format, which uses uint's 
to index into structure types and allows arbitrary 32- and 64-bit integer
types to index into sequential types.

llvm-svn: 12651
2004-04-05 01:27:26 +00:00

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//===-- InstructionWriter.cpp - Functions for writing instructions --------===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the routines for encoding instruction opcodes to a
// bytecode stream.
//
//===----------------------------------------------------------------------===//
#include "WriterInternals.h"
#include "llvm/Module.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Instructions.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
#include "Support/Statistic.h"
#include <algorithm>
using namespace llvm;
typedef unsigned char uchar;
// outputInstructionFormat0 - Output those wierd instructions that have a large
// number of operands or have large operands themselves...
//
// Format: [opcode] [type] [numargs] [arg0] [arg1] ... [arg<numargs-1>]
//
static void outputInstructionFormat0(const Instruction *I, unsigned Opcode,
const SlotCalculator &Table,
unsigned Type, std::deque<uchar> &Out) {
// Opcode must have top two bits clear...
output_vbr(Opcode << 2, Out); // Instruction Opcode ID
output_vbr(Type, Out); // Result type
unsigned NumArgs = I->getNumOperands();
output_vbr(NumArgs + (isa<CastInst>(I) || isa<VANextInst>(I) ||
isa<VAArgInst>(I)), Out);
if (!isa<GetElementPtrInst>(&I)) {
for (unsigned i = 0; i < NumArgs; ++i) {
int Slot = Table.getSlot(I->getOperand(i));
assert(Slot >= 0 && "No slot number for value!?!?");
output_vbr((unsigned)Slot, Out);
}
if (isa<CastInst>(I) || isa<VAArgInst>(I)) {
int Slot = Table.getSlot(I->getType());
assert(Slot != -1 && "Cast return type unknown?");
output_vbr((unsigned)Slot, Out);
} else if (const VANextInst *VAI = dyn_cast<VANextInst>(I)) {
int Slot = Table.getSlot(VAI->getArgType());
assert(Slot != -1 && "VarArg argument type unknown?");
output_vbr((unsigned)Slot, Out);
}
} else {
int Slot = Table.getSlot(I->getOperand(0));
assert(Slot >= 0 && "No slot number for value!?!?");
output_vbr(unsigned(Slot), Out);
// We need to encode the type of sequential type indices into their slot #
unsigned Idx = 1;
for (gep_type_iterator TI = gep_type_begin(I), E = gep_type_end(I);
Idx != NumArgs; ++TI, ++Idx) {
Slot = Table.getSlot(I->getOperand(Idx));
assert(Slot >= 0 && "No slot number for value!?!?");
if (isa<SequentialType>(*TI)) {
unsigned IdxId;
switch (I->getOperand(Idx)->getType()->getPrimitiveID()) {
default: assert(0 && "Unknown index type!");
case Type::UIntTyID: IdxId = 0; break;
case Type::IntTyID: IdxId = 1; break;
case Type::ULongTyID: IdxId = 2; break;
case Type::LongTyID: IdxId = 3; break;
}
Slot = (Slot << 2) | IdxId;
}
output_vbr(unsigned(Slot), Out);
}
}
align32(Out); // We must maintain correct alignment!
}
// outputInstrVarArgsCall - Output the absurdly annoying varargs function calls.
// This are more annoying than most because the signature of the call does not
// tell us anything about the types of the arguments in the varargs portion.
// Because of this, we encode (as type 0) all of the argument types explicitly
// before the argument value. This really sucks, but you shouldn't be using
// varargs functions in your code! *death to printf*!
//
// Format: [opcode] [type] [numargs] [arg0] [arg1] ... [arg<numargs-1>]
//
static void outputInstrVarArgsCall(const Instruction *I, unsigned Opcode,
const SlotCalculator &Table, unsigned Type,
std::deque<uchar> &Out) {
assert(isa<CallInst>(I) || isa<InvokeInst>(I));
// Opcode must have top two bits clear...
output_vbr(Opcode << 2, Out); // Instruction Opcode ID
output_vbr(Type, Out); // Result type (varargs type)
const PointerType *PTy = cast<PointerType>(I->getOperand(0)->getType());
const FunctionType *FTy = cast<FunctionType>(PTy->getElementType());
unsigned NumParams = FTy->getNumParams();
unsigned NumFixedOperands;
if (isa<CallInst>(I)) {
// Output an operand for the callee and each fixed argument, then two for
// each variable argument.
NumFixedOperands = 1+NumParams;
} else {
assert(isa<InvokeInst>(I) && "Not call or invoke??");
// Output an operand for the callee and destinations, then two for each
// variable argument.
NumFixedOperands = 3+NumParams;
}
output_vbr(2 * I->getNumOperands()-NumFixedOperands, Out);
// The type for the function has already been emitted in the type field of the
// instruction. Just emit the slot # now.
for (unsigned i = 0; i != NumFixedOperands; ++i) {
int Slot = Table.getSlot(I->getOperand(i));
assert(Slot >= 0 && "No slot number for value!?!?");
output_vbr((unsigned)Slot, Out);
}
for (unsigned i = NumFixedOperands, e = I->getNumOperands(); i != e; ++i) {
// Output Arg Type ID
int Slot = Table.getSlot(I->getOperand(i)->getType());
assert(Slot >= 0 && "No slot number for value!?!?");
output_vbr((unsigned)Slot, Out);
// Output arg ID itself
Slot = Table.getSlot(I->getOperand(i));
assert(Slot >= 0 && "No slot number for value!?!?");
output_vbr((unsigned)Slot, Out);
}
align32(Out); // We must maintain correct alignment!
}
// outputInstructionFormat1 - Output one operand instructions, knowing that no
// operand index is >= 2^12.
//
static void outputInstructionFormat1(const Instruction *I, unsigned Opcode,
const SlotCalculator &Table,
unsigned *Slots, unsigned Type,
std::deque<uchar> &Out) {
// bits Instruction format:
// --------------------------
// 01-00: Opcode type, fixed to 1.
// 07-02: Opcode
// 19-08: Resulting type plane
// 31-20: Operand #1 (if set to (2^12-1), then zero operands)
//
unsigned Bits = 1 | (Opcode << 2) | (Type << 8) | (Slots[0] << 20);
// cerr << "1 " << IType << " " << Type << " " << Slots[0] << endl;
output(Bits, Out);
}
// outputInstructionFormat2 - Output two operand instructions, knowing that no
// operand index is >= 2^8.
//
static void outputInstructionFormat2(const Instruction *I, unsigned Opcode,
const SlotCalculator &Table,
unsigned *Slots, unsigned Type,
std::deque<uchar> &Out) {
// bits Instruction format:
// --------------------------
// 01-00: Opcode type, fixed to 2.
// 07-02: Opcode
// 15-08: Resulting type plane
// 23-16: Operand #1
// 31-24: Operand #2
//
unsigned Bits = 2 | (Opcode << 2) | (Type << 8) |
(Slots[0] << 16) | (Slots[1] << 24);
// cerr << "2 " << IType << " " << Type << " " << Slots[0] << " "
// << Slots[1] << endl;
output(Bits, Out);
}
// outputInstructionFormat3 - Output three operand instructions, knowing that no
// operand index is >= 2^6.
//
static void outputInstructionFormat3(const Instruction *I, unsigned Opcode,
const SlotCalculator &Table,
unsigned *Slots, unsigned Type,
std::deque<uchar> &Out) {
// bits Instruction format:
// --------------------------
// 01-00: Opcode type, fixed to 3.
// 07-02: Opcode
// 13-08: Resulting type plane
// 19-14: Operand #1
// 25-20: Operand #2
// 31-26: Operand #3
//
unsigned Bits = 3 | (Opcode << 2) | (Type << 8) |
(Slots[0] << 14) | (Slots[1] << 20) | (Slots[2] << 26);
//cerr << "3 " << IType << " " << Type << " " << Slots[0] << " "
// << Slots[1] << " " << Slots[2] << endl;
output(Bits, Out);
}
void BytecodeWriter::outputInstruction(const Instruction &I) {
assert(I.getOpcode() < 62 && "Opcode too big???");
unsigned Opcode = I.getOpcode();
unsigned NumOperands = I.getNumOperands();
// Encode 'volatile load' as 62 and 'volatile store' as 63.
if (isa<LoadInst>(I) && cast<LoadInst>(I).isVolatile())
Opcode = 62;
if (isa<StoreInst>(I) && cast<StoreInst>(I).isVolatile())
Opcode = 63;
// Figure out which type to encode with the instruction. Typically we want
// the type of the first parameter, as opposed to the type of the instruction
// (for example, with setcc, we always know it returns bool, but the type of
// the first param is actually interesting). But if we have no arguments
// we take the type of the instruction itself.
//
const Type *Ty;
switch (I.getOpcode()) {
case Instruction::Select:
case Instruction::Malloc:
case Instruction::Alloca:
Ty = I.getType(); // These ALWAYS want to encode the return type
break;
case Instruction::Store:
Ty = I.getOperand(1)->getType(); // Encode the pointer type...
assert(isa<PointerType>(Ty) && "Store to nonpointer type!?!?");
break;
default: // Otherwise use the default behavior...
Ty = NumOperands ? I.getOperand(0)->getType() : I.getType();
break;
}
unsigned Type;
int Slot = Table.getSlot(Ty);
assert(Slot != -1 && "Type not available!!?!");
Type = (unsigned)Slot;
// Varargs calls and invokes are encoded entirely different from any other
// instructions.
if (const CallInst *CI = dyn_cast<CallInst>(&I)){
const PointerType *Ty =cast<PointerType>(CI->getCalledValue()->getType());
if (cast<FunctionType>(Ty->getElementType())->isVarArg()) {
outputInstrVarArgsCall(CI, Opcode, Table, Type, Out);
return;
}
} else if (const InvokeInst *II = dyn_cast<InvokeInst>(&I)) {
const PointerType *Ty =cast<PointerType>(II->getCalledValue()->getType());
if (cast<FunctionType>(Ty->getElementType())->isVarArg()) {
outputInstrVarArgsCall(II, Opcode, Table, Type, Out);
return;
}
}
if (NumOperands <= 3) {
// Make sure that we take the type number into consideration. We don't want
// to overflow the field size for the instruction format we select.
//
unsigned MaxOpSlot = Type;
unsigned Slots[3]; Slots[0] = (1 << 12)-1; // Marker to signify 0 operands
for (unsigned i = 0; i != NumOperands; ++i) {
int slot = Table.getSlot(I.getOperand(i));
assert(slot != -1 && "Broken bytecode!");
if (unsigned(slot) > MaxOpSlot) MaxOpSlot = unsigned(slot);
Slots[i] = unsigned(slot);
}
// Handle the special cases for various instructions...
if (isa<CastInst>(I) || isa<VAArgInst>(I)) {
// Cast has to encode the destination type as the second argument in the
// packet, or else we won't know what type to cast to!
Slots[1] = Table.getSlot(I.getType());
assert(Slots[1] != ~0U && "Cast return type unknown?");
if (Slots[1] > MaxOpSlot) MaxOpSlot = Slots[1];
NumOperands++;
} else if (const VANextInst *VANI = dyn_cast<VANextInst>(&I)) {
Slots[1] = Table.getSlot(VANI->getArgType());
assert(Slots[1] != ~0U && "va_next return type unknown?");
if (Slots[1] > MaxOpSlot) MaxOpSlot = Slots[1];
NumOperands++;
} else if (const GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(&I)) {
// We need to encode the type of sequential type indices into their slot #
unsigned Idx = 1;
for (gep_type_iterator I = gep_type_begin(GEP), E = gep_type_end(GEP);
I != E; ++I, ++Idx)
if (isa<SequentialType>(*I)) {
unsigned IdxId;
switch (GEP->getOperand(Idx)->getType()->getPrimitiveID()) {
default: assert(0 && "Unknown index type!");
case Type::UIntTyID: IdxId = 0; break;
case Type::IntTyID: IdxId = 1; break;
case Type::ULongTyID: IdxId = 2; break;
case Type::LongTyID: IdxId = 3; break;
}
Slots[Idx] = (Slots[Idx] << 2) | IdxId;
if (Slots[Idx] > MaxOpSlot) MaxOpSlot = Slots[Idx];
}
}
// Decide which instruction encoding to use. This is determined primarily
// by the number of operands, and secondarily by whether or not the max
// operand will fit into the instruction encoding. More operands == fewer
// bits per operand.
//
switch (NumOperands) {
case 0:
case 1:
if (MaxOpSlot < (1 << 12)-1) { // -1 because we use 4095 to indicate 0 ops
outputInstructionFormat1(&I, Opcode, Table, Slots, Type, Out);
return;
}
break;
case 2:
if (MaxOpSlot < (1 << 8)) {
outputInstructionFormat2(&I, Opcode, Table, Slots, Type, Out);
return;
}
break;
case 3:
if (MaxOpSlot < (1 << 6)) {
outputInstructionFormat3(&I, Opcode, Table, Slots, Type, Out);
return;
}
break;
default:
break;
}
}
// If we weren't handled before here, we either have a large number of
// operands or a large operand index that we are referring to.
outputInstructionFormat0(&I, Opcode, Table, Type, Out);
}
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