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llvm-mirror/lib/Bytecode/Writer/Writer.cpp
Chris Lattner 10b5a5c0da Do not emit FunctionBlock blocks for external functions. This shrinks 
bytecode files by about 8 bytes per external function

llvm-svn: 17859
2004-11-15 22:39:49 +00:00

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//===-- Writer.cpp - Library for writing LLVM bytecode files --------------===//
//
// 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 library implements the functionality defined in llvm/Bytecode/Writer.h
//
// Note that this file uses an unusual technique of outputting all the bytecode
// to a vector of unsigned char, then copies the vector to an ostream. The
// reason for this is that we must do "seeking" in the stream to do back-
// patching, and some very important ostreams that we want to support (like
// pipes) do not support seeking. :( :( :(
//
//===----------------------------------------------------------------------===//
#include "WriterInternals.h"
#include "llvm/Bytecode/WriteBytecodePass.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Instructions.h"
#include "llvm/Module.h"
#include "llvm/SymbolTable.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
#include "llvm/Support/Compressor.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/Statistic.h"
#include <cstring>
#include <algorithm>
using namespace llvm;
/// This value needs to be incremented every time the bytecode format changes
/// so that the reader can distinguish which format of the bytecode file has
/// been written.
/// @brief The bytecode version number
const unsigned BCVersionNum = 5;
static RegisterPass<WriteBytecodePass> X("emitbytecode", "Bytecode Writer");
static Statistic<>
BytesWritten("bytecodewriter", "Number of bytecode bytes written");
//===----------------------------------------------------------------------===//
//=== Output Primitives ===//
//===----------------------------------------------------------------------===//
// output - If a position is specified, it must be in the valid portion of the
// string... note that this should be inlined always so only the relevant IF
// body should be included.
inline void BytecodeWriter::output(unsigned i, int pos) {
if (pos == -1) { // Be endian clean, little endian is our friend
Out.push_back((unsigned char)i);
Out.push_back((unsigned char)(i >> 8));
Out.push_back((unsigned char)(i >> 16));
Out.push_back((unsigned char)(i >> 24));
} else {
Out[pos ] = (unsigned char)i;
Out[pos+1] = (unsigned char)(i >> 8);
Out[pos+2] = (unsigned char)(i >> 16);
Out[pos+3] = (unsigned char)(i >> 24);
}
}
inline void BytecodeWriter::output(int i) {
output((unsigned)i);
}
/// output_vbr - Output an unsigned value, by using the least number of bytes
/// possible. This is useful because many of our "infinite" values are really
/// very small most of the time; but can be large a few times.
/// Data format used: If you read a byte with the high bit set, use the low
/// seven bits as data and then read another byte.
inline void BytecodeWriter::output_vbr(uint64_t i) {
while (1) {
if (i < 0x80) { // done?
Out.push_back((unsigned char)i); // We know the high bit is clear...
return;
}
// Nope, we are bigger than a character, output the next 7 bits and set the
// high bit to say that there is more coming...
Out.push_back(0x80 | ((unsigned char)i & 0x7F));
i >>= 7; // Shift out 7 bits now...
}
}
inline void BytecodeWriter::output_vbr(unsigned i) {
while (1) {
if (i < 0x80) { // done?
Out.push_back((unsigned char)i); // We know the high bit is clear...
return;
}
// Nope, we are bigger than a character, output the next 7 bits and set the
// high bit to say that there is more coming...
Out.push_back(0x80 | ((unsigned char)i & 0x7F));
i >>= 7; // Shift out 7 bits now...
}
}
inline void BytecodeWriter::output_typeid(unsigned i) {
if (i <= 0x00FFFFFF)
this->output_vbr(i);
else {
this->output_vbr(0x00FFFFFF);
this->output_vbr(i);
}
}
inline void BytecodeWriter::output_vbr(int64_t i) {
if (i < 0)
output_vbr(((uint64_t)(-i) << 1) | 1); // Set low order sign bit...
else
output_vbr((uint64_t)i << 1); // Low order bit is clear.
}
inline void BytecodeWriter::output_vbr(int i) {
if (i < 0)
output_vbr(((unsigned)(-i) << 1) | 1); // Set low order sign bit...
else
output_vbr((unsigned)i << 1); // Low order bit is clear.
}
inline void BytecodeWriter::output(const std::string &s) {
unsigned Len = s.length();
output_vbr(Len ); // Strings may have an arbitrary length...
Out.insert(Out.end(), s.begin(), s.end());
}
inline void BytecodeWriter::output_data(const void *Ptr, const void *End) {
Out.insert(Out.end(), (const unsigned char*)Ptr, (const unsigned char*)End);
}
inline void BytecodeWriter::output_float(float& FloatVal) {
/// FIXME: This isn't optimal, it has size problems on some platforms
/// where FP is not IEEE.
union {
float f;
uint32_t i;
} FloatUnion;
FloatUnion.f = FloatVal;
Out.push_back( static_cast<unsigned char>( (FloatUnion.i & 0xFF )));
Out.push_back( static_cast<unsigned char>( (FloatUnion.i >> 8) & 0xFF));
Out.push_back( static_cast<unsigned char>( (FloatUnion.i >> 16) & 0xFF));
Out.push_back( static_cast<unsigned char>( (FloatUnion.i >> 24) & 0xFF));
}
inline void BytecodeWriter::output_double(double& DoubleVal) {
/// FIXME: This isn't optimal, it has size problems on some platforms
/// where FP is not IEEE.
union {
double d;
uint64_t i;
} DoubleUnion;
DoubleUnion.d = DoubleVal;
Out.push_back( static_cast<unsigned char>( (DoubleUnion.i & 0xFF )));
Out.push_back( static_cast<unsigned char>( (DoubleUnion.i >> 8) & 0xFF));
Out.push_back( static_cast<unsigned char>( (DoubleUnion.i >> 16) & 0xFF));
Out.push_back( static_cast<unsigned char>( (DoubleUnion.i >> 24) & 0xFF));
Out.push_back( static_cast<unsigned char>( (DoubleUnion.i >> 32) & 0xFF));
Out.push_back( static_cast<unsigned char>( (DoubleUnion.i >> 40) & 0xFF));
Out.push_back( static_cast<unsigned char>( (DoubleUnion.i >> 48) & 0xFF));
Out.push_back( static_cast<unsigned char>( (DoubleUnion.i >> 56) & 0xFF));
}
inline BytecodeBlock::BytecodeBlock(unsigned ID, BytecodeWriter& w,
bool elideIfEmpty, bool hasLongFormat )
: Id(ID), Writer(w), ElideIfEmpty(elideIfEmpty), HasLongFormat(hasLongFormat){
if (HasLongFormat) {
w.output(ID);
w.output(0U); // For length in long format
} else {
w.output(0U); /// Place holder for ID and length for this block
}
Loc = w.size();
}
inline BytecodeBlock::~BytecodeBlock() { // Do backpatch when block goes out
// of scope...
if (Loc == Writer.size() && ElideIfEmpty) {
// If the block is empty, and we are allowed to, do not emit the block at
// all!
Writer.resize(Writer.size()-(HasLongFormat?8:4));
return;
}
if (HasLongFormat)
Writer.output(unsigned(Writer.size()-Loc), int(Loc-4));
else
Writer.output(unsigned(Writer.size()-Loc) << 5 | (Id & 0x1F), int(Loc-4));
}
//===----------------------------------------------------------------------===//
//=== Constant Output ===//
//===----------------------------------------------------------------------===//
void BytecodeWriter::outputType(const Type *T) {
output_vbr((unsigned)T->getTypeID());
// That's all there is to handling primitive types...
if (T->isPrimitiveType()) {
return; // We might do this if we alias a prim type: %x = type int
}
switch (T->getTypeID()) { // Handle derived types now.
case Type::FunctionTyID: {
const FunctionType *MT = cast<FunctionType>(T);
int Slot = Table.getSlot(MT->getReturnType());
assert(Slot != -1 && "Type used but not available!!");
output_typeid((unsigned)Slot);
// Output the number of arguments to function (+1 if varargs):
output_vbr((unsigned)MT->getNumParams()+MT->isVarArg());
// Output all of the arguments...
FunctionType::param_iterator I = MT->param_begin();
for (; I != MT->param_end(); ++I) {
Slot = Table.getSlot(*I);
assert(Slot != -1 && "Type used but not available!!");
output_typeid((unsigned)Slot);
}
// Terminate list with VoidTy if we are a varargs function...
if (MT->isVarArg())
output_typeid((unsigned)Type::VoidTyID);
break;
}
case Type::ArrayTyID: {
const ArrayType *AT = cast<ArrayType>(T);
int Slot = Table.getSlot(AT->getElementType());
assert(Slot != -1 && "Type used but not available!!");
output_typeid((unsigned)Slot);
output_vbr(AT->getNumElements());
break;
}
case Type::PackedTyID: {
const PackedType *PT = cast<PackedType>(T);
int Slot = Table.getSlot(PT->getElementType());
assert(Slot != -1 && "Type used but not available!!");
output_typeid((unsigned)Slot);
output_vbr(PT->getNumElements());
break;
}
case Type::StructTyID: {
const StructType *ST = cast<StructType>(T);
// Output all of the element types...
for (StructType::element_iterator I = ST->element_begin(),
E = ST->element_end(); I != E; ++I) {
int Slot = Table.getSlot(*I);
assert(Slot != -1 && "Type used but not available!!");
output_typeid((unsigned)Slot);
}
// Terminate list with VoidTy
output_typeid((unsigned)Type::VoidTyID);
break;
}
case Type::PointerTyID: {
const PointerType *PT = cast<PointerType>(T);
int Slot = Table.getSlot(PT->getElementType());
assert(Slot != -1 && "Type used but not available!!");
output_typeid((unsigned)Slot);
break;
}
case Type::OpaqueTyID:
// No need to emit anything, just the count of opaque types is enough.
break;
default:
std::cerr << __FILE__ << ":" << __LINE__ << ": Don't know how to serialize"
<< " Type '" << T->getDescription() << "'\n";
break;
}
}
void BytecodeWriter::outputConstant(const Constant *CPV) {
assert((CPV->getType()->isPrimitiveType() || !CPV->isNullValue()) &&
"Shouldn't output null constants!");
// We must check for a ConstantExpr before switching by type because
// a ConstantExpr can be of any type, and has no explicit value.
//
if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(CPV)) {
// FIXME: Encoding of constant exprs could be much more compact!
assert(CE->getNumOperands() > 0 && "ConstantExpr with 0 operands");
output_vbr(1+CE->getNumOperands()); // flags as an expr
output_vbr(CE->getOpcode()); // flags as an expr
for (User::const_op_iterator OI = CE->op_begin(); OI != CE->op_end(); ++OI){
int Slot = Table.getSlot(*OI);
assert(Slot != -1 && "Unknown constant used in ConstantExpr!!");
output_vbr((unsigned)Slot);
Slot = Table.getSlot((*OI)->getType());
output_typeid((unsigned)Slot);
}
return;
} else if (isa<UndefValue>(CPV)) {
output_vbr(1U); // 1 -> UndefValue constant.
return;
} else {
output_vbr(0U); // flag as not a ConstantExpr
}
switch (CPV->getType()->getTypeID()) {
case Type::BoolTyID: // Boolean Types
if (cast<ConstantBool>(CPV)->getValue())
output_vbr(1U);
else
output_vbr(0U);
break;
case Type::UByteTyID: // Unsigned integer types...
case Type::UShortTyID:
case Type::UIntTyID:
case Type::ULongTyID:
output_vbr(cast<ConstantUInt>(CPV)->getValue());
break;
case Type::SByteTyID: // Signed integer types...
case Type::ShortTyID:
case Type::IntTyID:
case Type::LongTyID:
output_vbr(cast<ConstantSInt>(CPV)->getValue());
break;
case Type::ArrayTyID: {
const ConstantArray *CPA = cast<ConstantArray>(CPV);
assert(!CPA->isString() && "Constant strings should be handled specially!");
for (unsigned i = 0, e = CPA->getNumOperands(); i != e; ++i) {
int Slot = Table.getSlot(CPA->getOperand(i));
assert(Slot != -1 && "Constant used but not available!!");
output_vbr((unsigned)Slot);
}
break;
}
case Type::PackedTyID: {
const ConstantPacked *CP = cast<ConstantPacked>(CPV);
for (unsigned i = 0, e = CP->getNumOperands(); i != e; ++i) {
int Slot = Table.getSlot(CP->getOperand(i));
assert(Slot != -1 && "Constant used but not available!!");
output_vbr((unsigned)Slot);
}
break;
}
case Type::StructTyID: {
const ConstantStruct *CPS = cast<ConstantStruct>(CPV);
for (unsigned i = 0, e = CPS->getNumOperands(); i != e; ++i) {
int Slot = Table.getSlot(CPS->getOperand(i));
assert(Slot != -1 && "Constant used but not available!!");
output_vbr((unsigned)Slot);
}
break;
}
case Type::PointerTyID:
assert(0 && "No non-null, non-constant-expr constants allowed!");
abort();
case Type::FloatTyID: { // Floating point types...
float Tmp = (float)cast<ConstantFP>(CPV)->getValue();
output_float(Tmp);
break;
}
case Type::DoubleTyID: {
double Tmp = cast<ConstantFP>(CPV)->getValue();
output_double(Tmp);
break;
}
case Type::VoidTyID:
case Type::LabelTyID:
default:
std::cerr << __FILE__ << ":" << __LINE__ << ": Don't know how to serialize"
<< " type '" << *CPV->getType() << "'\n";
break;
}
return;
}
void BytecodeWriter::outputConstantStrings() {
SlotCalculator::string_iterator I = Table.string_begin();
SlotCalculator::string_iterator E = Table.string_end();
if (I == E) return; // No strings to emit
// If we have != 0 strings to emit, output them now. Strings are emitted into
// the 'void' type plane.
output_vbr(unsigned(E-I));
output_typeid(Type::VoidTyID);
// Emit all of the strings.
for (I = Table.string_begin(); I != E; ++I) {
const ConstantArray *Str = *I;
int Slot = Table.getSlot(Str->getType());
assert(Slot != -1 && "Constant string of unknown type?");
output_typeid((unsigned)Slot);
// Now that we emitted the type (which indicates the size of the string),
// emit all of the characters.
std::string Val = Str->getAsString();
output_data(Val.c_str(), Val.c_str()+Val.size());
}
}
//===----------------------------------------------------------------------===//
//=== Instruction Output ===//
//===----------------------------------------------------------------------===//
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>]
//
void BytecodeWriter::outputInstructionFormat0(const Instruction *I,
unsigned Opcode,
const SlotCalculator &Table,
unsigned Type) {
// Opcode must have top two bits clear...
output_vbr(Opcode << 2); // Instruction Opcode ID
output_typeid(Type); // Result type
unsigned NumArgs = I->getNumOperands();
output_vbr(NumArgs + (isa<CastInst>(I) || isa<VANextInst>(I) ||
isa<VAArgInst>(I)));
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);
}
if (isa<CastInst>(I) || isa<VAArgInst>(I)) {
int Slot = Table.getSlot(I->getType());
assert(Slot != -1 && "Cast return type unknown?");
output_typeid((unsigned)Slot);
} else if (const VANextInst *VAI = dyn_cast<VANextInst>(I)) {
int Slot = Table.getSlot(VAI->getArgType());
assert(Slot != -1 && "VarArg argument type unknown?");
output_typeid((unsigned)Slot);
}
} else {
int Slot = Table.getSlot(I->getOperand(0));
assert(Slot >= 0 && "No slot number for value!?!?");
output_vbr(unsigned(Slot));
// 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()->getTypeID()) {
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));
}
}
}
// 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>]
//
void BytecodeWriter::outputInstrVarArgsCall(const Instruction *I,
unsigned Opcode,
const SlotCalculator &Table,
unsigned Type) {
assert(isa<CallInst>(I) || isa<InvokeInst>(I));
// Opcode must have top two bits clear...
output_vbr(Opcode << 2); // Instruction Opcode ID
output_typeid(Type); // 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);
// 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);
}
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_typeid((unsigned)Slot);
// Output arg ID itself
Slot = Table.getSlot(I->getOperand(i));
assert(Slot >= 0 && "No slot number for value!?!?");
output_vbr((unsigned)Slot);
}
}
// outputInstructionFormat1 - Output one operand instructions, knowing that no
// operand index is >= 2^12.
//
inline void BytecodeWriter::outputInstructionFormat1(const Instruction *I,
unsigned Opcode,
unsigned *Slots,
unsigned Type) {
// 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)
//
output(1 | (Opcode << 2) | (Type << 8) | (Slots[0] << 20));
}
// outputInstructionFormat2 - Output two operand instructions, knowing that no
// operand index is >= 2^8.
//
inline void BytecodeWriter::outputInstructionFormat2(const Instruction *I,
unsigned Opcode,
unsigned *Slots,
unsigned Type) {
// 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
//
output(2 | (Opcode << 2) | (Type << 8) | (Slots[0] << 16) | (Slots[1] << 24));
}
// outputInstructionFormat3 - Output three operand instructions, knowing that no
// operand index is >= 2^6.
//
inline void BytecodeWriter::outputInstructionFormat3(const Instruction *I,
unsigned Opcode,
unsigned *Slots,
unsigned Type) {
// 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
//
output(3 | (Opcode << 2) | (Type << 8) |
(Slots[0] << 14) | (Slots[1] << 20) | (Slots[2] << 26));
}
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);
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);
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()->getTypeID()) {
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, Slots, Type);
return;
}
break;
case 2:
if (MaxOpSlot < (1 << 8)) {
outputInstructionFormat2(&I, Opcode, Slots, Type);
return;
}
break;
case 3:
if (MaxOpSlot < (1 << 6)) {
outputInstructionFormat3(&I, Opcode, Slots, Type);
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);
}
//===----------------------------------------------------------------------===//
//=== Block Output ===//
//===----------------------------------------------------------------------===//
BytecodeWriter::BytecodeWriter(std::vector<unsigned char> &o, const Module *M)
: Out(o), Table(M) {
// Emit the signature...
static const unsigned char *Sig = (const unsigned char*)"llvm";
output_data(Sig, Sig+4);
// Emit the top level CLASS block.
BytecodeBlock ModuleBlock(BytecodeFormat::ModuleBlockID, *this, false, true);
bool isBigEndian = M->getEndianness() == Module::BigEndian;
bool hasLongPointers = M->getPointerSize() == Module::Pointer64;
bool hasNoEndianness = M->getEndianness() == Module::AnyEndianness;
bool hasNoPointerSize = M->getPointerSize() == Module::AnyPointerSize;
// Output the version identifier and other information.
unsigned Version = (BCVersionNum << 4) |
(unsigned)isBigEndian | (hasLongPointers << 1) |
(hasNoEndianness << 2) |
(hasNoPointerSize << 3);
output_vbr(Version);
// The Global type plane comes first
{
BytecodeBlock CPool(BytecodeFormat::GlobalTypePlaneBlockID, *this );
outputTypes(Type::FirstDerivedTyID);
}
// The ModuleInfoBlock follows directly after the type information
outputModuleInfoBlock(M);
// Output module level constants, used for global variable initializers
outputConstants(false);
// Do the whole module now! Process each function at a time...
for (Module::const_iterator I = M->begin(), E = M->end(); I != E; ++I)
outputFunction(I);
// If needed, output the symbol table for the module...
outputSymbolTable(M->getSymbolTable());
}
void BytecodeWriter::outputTypes(unsigned TypeNum) {
// Write the type plane for types first because earlier planes (e.g. for a
// primitive type like float) may have constants constructed using types
// coming later (e.g., via getelementptr from a pointer type). The type
// plane is needed before types can be fwd or bkwd referenced.
const std::vector<const Type*>& Types = Table.getTypes();
assert(!Types.empty() && "No types at all?");
assert(TypeNum <= Types.size() && "Invalid TypeNo index");
unsigned NumEntries = Types.size() - TypeNum;
// Output type header: [num entries]
output_vbr(NumEntries);
for (unsigned i = TypeNum; i < TypeNum+NumEntries; ++i)
outputType(Types[i]);
}
// Helper function for outputConstants().
// Writes out all the constants in the plane Plane starting at entry StartNo.
//
void BytecodeWriter::outputConstantsInPlane(const std::vector<const Value*>
&Plane, unsigned StartNo) {
unsigned ValNo = StartNo;
// Scan through and ignore function arguments, global values, and constant
// strings.
for (; ValNo < Plane.size() &&
(isa<Argument>(Plane[ValNo]) || isa<GlobalValue>(Plane[ValNo]) ||
(isa<ConstantArray>(Plane[ValNo]) &&
cast<ConstantArray>(Plane[ValNo])->isString())); ValNo++)
/*empty*/;
unsigned NC = ValNo; // Number of constants
for (; NC < Plane.size() && (isa<Constant>(Plane[NC])); NC++)
/*empty*/;
NC -= ValNo; // Convert from index into count
if (NC == 0) return; // Skip empty type planes...
// FIXME: Most slabs only have 1 or 2 entries! We should encode this much
// more compactly.
// Output type header: [num entries][type id number]
//
output_vbr(NC);
// Output the Type ID Number...
int Slot = Table.getSlot(Plane.front()->getType());
assert (Slot != -1 && "Type in constant pool but not in function!!");
output_typeid((unsigned)Slot);
for (unsigned i = ValNo; i < ValNo+NC; ++i) {
const Value *V = Plane[i];
if (const Constant *C = dyn_cast<Constant>(V)) {
outputConstant(C);
}
}
}
static inline bool hasNullValue(unsigned TyID) {
return TyID != Type::LabelTyID && TyID != Type::VoidTyID;
}
void BytecodeWriter::outputConstants(bool isFunction) {
BytecodeBlock CPool(BytecodeFormat::ConstantPoolBlockID, *this,
true /* Elide block if empty */);
unsigned NumPlanes = Table.getNumPlanes();
if (isFunction)
// Output the type plane before any constants!
outputTypes(Table.getModuleTypeLevel());
else
// Output module-level string constants before any other constants.
outputConstantStrings();
for (unsigned pno = 0; pno != NumPlanes; pno++) {
const std::vector<const Value*> &Plane = Table.getPlane(pno);
if (!Plane.empty()) { // Skip empty type planes...
unsigned ValNo = 0;
if (isFunction) // Don't re-emit module constants
ValNo += Table.getModuleLevel(pno);
if (hasNullValue(pno)) {
// Skip zero initializer
if (ValNo == 0)
ValNo = 1;
}
// Write out constants in the plane
outputConstantsInPlane(Plane, ValNo);
}
}
}
static unsigned getEncodedLinkage(const GlobalValue *GV) {
switch (GV->getLinkage()) {
default: assert(0 && "Invalid linkage!");
case GlobalValue::ExternalLinkage: return 0;
case GlobalValue::WeakLinkage: return 1;
case GlobalValue::AppendingLinkage: return 2;
case GlobalValue::InternalLinkage: return 3;
case GlobalValue::LinkOnceLinkage: return 4;
}
}
void BytecodeWriter::outputModuleInfoBlock(const Module *M) {
BytecodeBlock ModuleInfoBlock(BytecodeFormat::ModuleGlobalInfoBlockID, *this);
// Output the types for the global variables in the module...
for (Module::const_giterator I = M->gbegin(), End = M->gend(); I != End;++I) {
int Slot = Table.getSlot(I->getType());
assert(Slot != -1 && "Module global vars is broken!");
// Fields: bit0 = isConstant, bit1 = hasInitializer, bit2-4=Linkage,
// bit5+ = Slot # for type
unsigned oSlot = ((unsigned)Slot << 5) | (getEncodedLinkage(I) << 2) |
(I->hasInitializer() << 1) | (unsigned)I->isConstant();
output_vbr(oSlot);
// If we have an initializer, output it now.
if (I->hasInitializer()) {
Slot = Table.getSlot((Value*)I->getInitializer());
assert(Slot != -1 && "No slot for global var initializer!");
output_vbr((unsigned)Slot);
}
}
output_typeid((unsigned)Table.getSlot(Type::VoidTy));
// Output the types of the functions in this module.
for (Module::const_iterator I = M->begin(), End = M->end(); I != End; ++I) {
int Slot = Table.getSlot(I->getType());
assert(Slot != -1 && "Module slot calculator is broken!");
assert(Slot >= Type::FirstDerivedTyID && "Derived type not in range!");
assert(((Slot << 5) >> 5) == Slot && "Slot # too big!");
unsigned ID = (Slot << 5) + 1;
if (I->isExternal()) // If external, we don't have an FunctionInfo block.
ID |= 1 << 4;
output_vbr(ID);
}
output_vbr((unsigned)Table.getSlot(Type::VoidTy) << 5);
// Emit the list of dependent libraries for the Module.
Module::lib_iterator LI = M->lib_begin();
Module::lib_iterator LE = M->lib_end();
output_vbr(unsigned(LE - LI)); // Emit the number of dependent libraries.
for (; LI != LE; ++LI)
output(*LI);
// Output the target triple from the module
output(M->getTargetTriple());
}
void BytecodeWriter::outputInstructions(const Function *F) {
BytecodeBlock ILBlock(BytecodeFormat::InstructionListBlockID, *this);
for (Function::const_iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I!=E; ++I)
outputInstruction(*I);
}
void BytecodeWriter::outputFunction(const Function *F) {
// If this is an external function, there is nothing else to emit!
if (F->isExternal()) return;
BytecodeBlock FunctionBlock(BytecodeFormat::FunctionBlockID, *this);
output_vbr(getEncodedLinkage(F));
// Get slot information about the function...
Table.incorporateFunction(F);
if (Table.getCompactionTable().empty()) {
// Output information about the constants in the function if the compaction
// table is not being used.
outputConstants(true);
} else {
// Otherwise, emit the compaction table.
outputCompactionTable();
}
// Output all of the instructions in the body of the function
outputInstructions(F);
// If needed, output the symbol table for the function...
outputSymbolTable(F->getSymbolTable());
Table.purgeFunction();
}
void BytecodeWriter::outputCompactionTablePlane(unsigned PlaneNo,
const std::vector<const Value*> &Plane,
unsigned StartNo) {
unsigned End = Table.getModuleLevel(PlaneNo);
if (Plane.empty() || StartNo == End || End == 0) return; // Nothing to emit
assert(StartNo < End && "Cannot emit negative range!");
assert(StartNo < Plane.size() && End <= Plane.size());
// Do not emit the null initializer!
++StartNo;
// Figure out which encoding to use. By far the most common case we have is
// to emit 0-2 entries in a compaction table plane.
switch (End-StartNo) {
case 0: // Avoid emitting two vbr's if possible.
case 1:
case 2:
output_vbr((PlaneNo << 2) | End-StartNo);
break;
default:
// Output the number of things.
output_vbr((unsigned(End-StartNo) << 2) | 3);
output_typeid(PlaneNo); // Emit the type plane this is
break;
}
for (unsigned i = StartNo; i != End; ++i)
output_vbr(Table.getGlobalSlot(Plane[i]));
}
void BytecodeWriter::outputCompactionTypes(unsigned StartNo) {
// Get the compaction type table from the slot calculator
const std::vector<const Type*> &CTypes = Table.getCompactionTypes();
// The compaction types may have been uncompactified back to the
// global types. If so, we just write an empty table
if (CTypes.size() == 0 ) {
output_vbr(0U);
return;
}
assert(CTypes.size() >= StartNo && "Invalid compaction types start index");
// Determine how many types to write
unsigned NumTypes = CTypes.size() - StartNo;
// Output the number of types.
output_vbr(NumTypes);
for (unsigned i = StartNo; i < StartNo+NumTypes; ++i)
output_typeid(Table.getGlobalSlot(CTypes[i]));
}
void BytecodeWriter::outputCompactionTable() {
// Avoid writing the compaction table at all if there is no content.
if (Table.getCompactionTypes().size() >= Type::FirstDerivedTyID ||
(!Table.CompactionTableIsEmpty())) {
BytecodeBlock CTB(BytecodeFormat::CompactionTableBlockID, *this,
true/*ElideIfEmpty*/);
const std::vector<std::vector<const Value*> > &CT =
Table.getCompactionTable();
// First things first, emit the type compaction table if there is one.
outputCompactionTypes(Type::FirstDerivedTyID);
for (unsigned i = 0, e = CT.size(); i != e; ++i)
outputCompactionTablePlane(i, CT[i], 0);
}
}
void BytecodeWriter::outputSymbolTable(const SymbolTable &MST) {
// Do not output the Bytecode block for an empty symbol table, it just wastes
// space!
if (MST.isEmpty()) return;
BytecodeBlock SymTabBlock(BytecodeFormat::SymbolTableBlockID, *this,
true/*ElideIfEmpty*/);
// Write the number of types
output_vbr(MST.num_types());
// Write each of the types
for (SymbolTable::type_const_iterator TI = MST.type_begin(),
TE = MST.type_end(); TI != TE; ++TI ) {
// Symtab entry:[def slot #][name]
output_typeid((unsigned)Table.getSlot(TI->second));
output(TI->first);
}
// Now do each of the type planes in order.
for (SymbolTable::plane_const_iterator PI = MST.plane_begin(),
PE = MST.plane_end(); PI != PE; ++PI) {
SymbolTable::value_const_iterator I = MST.value_begin(PI->first);
SymbolTable::value_const_iterator End = MST.value_end(PI->first);
int Slot;
if (I == End) continue; // Don't mess with an absent type...
// Write the number of values in this plane
output_vbr(MST.type_size(PI->first));
// Write the slot number of the type for this plane
Slot = Table.getSlot(PI->first);
assert(Slot != -1 && "Type in symtab, but not in table!");
output_typeid((unsigned)Slot);
// Write each of the values in this plane
for (; I != End; ++I) {
// Symtab entry: [def slot #][name]
Slot = Table.getSlot(I->second);
assert(Slot != -1 && "Value in symtab but has no slot number!!");
output_vbr((unsigned)Slot);
output(I->first);
}
}
}
void llvm::WriteBytecodeToFile(const Module *M, std::ostream &Out,
bool compress ) {
assert(M && "You can't write a null module!!");
// Create a vector of unsigned char for the bytecode output. We
// reserve 256KBytes of space in the vector so that we avoid doing
// lots of little allocations. 256KBytes is sufficient for a large
// proportion of the bytecode files we will encounter. Larger files
// will be automatically doubled in size as needed (std::vector
// behavior).
std::vector<unsigned char> Buffer;
Buffer.reserve(256 * 1024);
// The BytecodeWriter populates Buffer for us.
BytecodeWriter BCW(Buffer, M);
// Keep track of how much we've written
BytesWritten += Buffer.size();
// Determine start and end points of the Buffer
const unsigned char *FirstByte = &Buffer.front();
// If we're supposed to compress this mess ...
if (compress) {
// We signal compression by using an alternate magic number for the
// file. The compressed bytecode file's magic number is "llvc" instead
// of "llvm".
char compressed_magic[4];
compressed_magic[0] = 'l';
compressed_magic[1] = 'l';
compressed_magic[2] = 'v';
compressed_magic[3] = 'c';
Out.write(compressed_magic,4);
// Compress everything after the magic number (which we altered)
uint64_t zipSize = Compressor::compressToStream(
(char*)(FirstByte+4), // Skip the magic number
Buffer.size()-4, // Skip the magic number
Out, // Where to write compressed data
Compressor::COMP_TYPE_BZIP2 // Try bzip2 compression first
);
} else {
// We're not compressing, so just write the entire block.
Out.write((char*)FirstByte, Buffer.size());
}
// make sure it hits disk now
Out.flush();
}
// vim: sw=2 ai
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