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llvm-6502/lib/Bytecode/Writer/Writer.cpp
Chris Lattner 972b4dccaf getTypeSlot can never fail 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@34129 91177308-0d34-0410-b5e6-96231b3b80d8
2007-02-10 05:17:48 +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. :( :( :(
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "bytecodewriter"
#include "WriterInternals.h"
#include "llvm/Bytecode/WriteBytecodePass.h"
#include "llvm/CallingConv.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/InlineAsm.h"
#include "llvm/Instructions.h"
#include "llvm/Module.h"
#include "llvm/TypeSymbolTable.h"
#include "llvm/ValueSymbolTable.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
#include "llvm/Support/Compressor.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/Streams.h"
#include "llvm/System/Program.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 = 7;
static RegisterPass<WriteBytecodePass> X("emitbytecode", "Bytecode Writer");
STATISTIC(BytesWritten, "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(int32_t i) {
output((uint32_t)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(uint32_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_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.
uint32_t i = FloatToBits(FloatVal);
Out.push_back( static_cast<unsigned char>( (i ) & 0xFF));
Out.push_back( static_cast<unsigned char>( (i >> 8 ) & 0xFF));
Out.push_back( static_cast<unsigned char>( (i >> 16) & 0xFF));
Out.push_back( static_cast<unsigned char>( (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.
uint64_t i = DoubleToBits(DoubleVal);
Out.push_back( static_cast<unsigned char>( (i ) & 0xFF));
Out.push_back( static_cast<unsigned char>( (i >> 8 ) & 0xFF));
Out.push_back( static_cast<unsigned char>( (i >> 16) & 0xFF));
Out.push_back( static_cast<unsigned char>( (i >> 24) & 0xFF));
Out.push_back( static_cast<unsigned char>( (i >> 32) & 0xFF));
Out.push_back( static_cast<unsigned char>( (i >> 40) & 0xFF));
Out.push_back( static_cast<unsigned char>( (i >> 48) & 0xFF));
Out.push_back( static_cast<unsigned char>( (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) {
const StructType* STy = dyn_cast<StructType>(T);
if(STy && STy->isPacked())
output_vbr((unsigned)Type::PackedStructTyID);
else
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::IntegerTyID:
output_vbr(cast<IntegerType>(T)->getBitWidth());
break;
case Type::FunctionTyID: {
const FunctionType *MT = cast<FunctionType>(T);
output_typeid(Table.getTypeSlot(MT->getReturnType()));
output_vbr(unsigned(MT->getParamAttrs(0)));
// 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();
unsigned Idx = 1;
for (; I != MT->param_end(); ++I) {
output_typeid(Table.getTypeSlot(*I));
output_vbr(unsigned(MT->getParamAttrs(Idx)));
Idx++;
}
// 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);
output_typeid(Table.getTypeSlot(AT->getElementType()));
output_vbr(AT->getNumElements());
break;
}
case Type::PackedTyID: {
const PackedType *PT = cast<PackedType>(T);
output_typeid(Table.getTypeSlot(PT->getElementType()));
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) {
output_typeid(Table.getTypeSlot(*I));
}
// Terminate list with VoidTy
output_typeid((unsigned)Type::VoidTyID);
break;
}
case Type::PointerTyID:
output_typeid(Table.getTypeSlot(cast<PointerType>(T)->getElementType()));
break;
case Type::OpaqueTyID:
// No need to emit anything, just the count of opaque types is enough.
break;
default:
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->getType()->isInteger()) ||
!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");
assert(CE->getNumOperands() != 1 || CE->isCast());
output_vbr(1+CE->getNumOperands()); // flags as an expr
output_vbr(CE->getOpcode()); // Put out the CE op code
for (User::const_op_iterator OI = CE->op_begin(); OI != CE->op_end(); ++OI){
output_vbr(Table.getSlot(*OI));
output_typeid(Table.getTypeSlot((*OI)->getType()));
}
if (CE->isCompare())
output_vbr((unsigned)CE->getPredicate());
return;
} else if (isa<UndefValue>(CPV)) {
output_vbr(1U); // 1 -> UndefValue constant.
return;
} else {
output_vbr(0U); // flag as not a ConstantExpr (i.e. 0 operands)
}
switch (CPV->getType()->getTypeID()) {
case Type::IntegerTyID: { // Integer types...
unsigned NumBits = cast<IntegerType>(CPV->getType())->getBitWidth();
if (NumBits <= 32)
output_vbr(uint32_t(cast<ConstantInt>(CPV)->getZExtValue()));
else if (NumBits <= 64)
output_vbr(uint64_t(cast<ConstantInt>(CPV)->getZExtValue()));
else
assert("Integer types > 64 bits not supported.");
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)
output_vbr(Table.getSlot(CPA->getOperand(i)));
break;
}
case Type::PackedTyID: {
const ConstantPacked *CP = cast<ConstantPacked>(CPV);
for (unsigned i = 0, e = CP->getNumOperands(); i != e; ++i)
output_vbr(Table.getSlot(CP->getOperand(i)));
break;
}
case Type::StructTyID: {
const ConstantStruct *CPS = cast<ConstantStruct>(CPV);
for (unsigned i = 0, e = CPS->getNumOperands(); i != e; ++i)
output_vbr(Table.getSlot(CPS->getOperand(i)));
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:
cerr << __FILE__ << ":" << __LINE__ << ": Don't know how to serialize"
<< " type '" << *CPV->getType() << "'\n";
break;
}
return;
}
/// outputInlineAsm - InlineAsm's get emitted to the constant pool, so they can
/// be shared by multiple uses.
void BytecodeWriter::outputInlineAsm(const InlineAsm *IA) {
// Output a marker, so we know when we have one one parsing the constant pool.
// Note that this encoding is 5 bytes: not very efficient for a marker. Since
// unique inline asms are rare, this should hardly matter.
output_vbr(~0U);
output(IA->getAsmString());
output(IA->getConstraintString());
output_vbr(unsigned(IA->hasSideEffects()));
}
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;
output_typeid(Table.getTypeSlot(Str->getType()));
// 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 ===//
//===----------------------------------------------------------------------===//
// outputInstructionFormat0 - Output those weird 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<InvokeInst>(I) ||
isa<CmpInst>(I) || isa<VAArgInst>(I) || Opcode == 58));
if (!isa<GetElementPtrInst>(&I)) {
for (unsigned i = 0; i < NumArgs; ++i)
output_vbr(Table.getSlot(I->getOperand(i)));
if (isa<CastInst>(I) || isa<VAArgInst>(I)) {
output_typeid(Table.getTypeSlot(I->getType()));
} else if (isa<CmpInst>(I)) {
output_vbr(unsigned(cast<CmpInst>(I)->getPredicate()));
} else if (isa<InvokeInst>(I)) {
output_vbr(cast<InvokeInst>(I)->getCallingConv());
} else if (Opcode == 58) { // Call escape sequence
output_vbr((cast<CallInst>(I)->getCallingConv() << 1) |
unsigned(cast<CallInst>(I)->isTailCall()));
}
} else {
output_vbr(Table.getSlot(I->getOperand(0)));
// 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) {
unsigned Slot = Table.getSlot(I->getOperand(Idx));
if (isa<SequentialType>(*TI)) {
// These should be either 32-bits or 64-bits, however, with bit
// accurate types we just distinguish between less than or equal to
// 32-bits or greater than 32-bits.
unsigned BitWidth =
cast<IntegerType>(I->getOperand(Idx)->getType())->getBitWidth();
assert(BitWidth == 32 || BitWidth == 64 &&
"Invalid bitwidth for GEP index");
unsigned IdxId = BitWidth == 32 ? 0 : 1;
Slot = (Slot << 1) | IdxId;
}
output_vbr(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 +
unsigned(Opcode == 58 || isa<InvokeInst>(I)));
// 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)
output_vbr(Table.getSlot(I->getOperand(i)));
for (unsigned i = NumFixedOperands, e = I->getNumOperands(); i != e; ++i) {
// Output Arg Type ID
output_typeid(Table.getTypeSlot(I->getOperand(i)->getType()));
// Output arg ID itself
output_vbr(Table.getSlot(I->getOperand(i)));
}
if (isa<InvokeInst>(I)) {
// Emit the tail call/calling conv for invoke instructions
output_vbr(cast<InvokeInst>(I)->getCallingConv());
} else if (Opcode == 58) {
const CallInst *CI = cast<CallInst>(I);
output_vbr((CI->getCallingConv() << 1) | unsigned(CI->isTailCall()));
}
}
// 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() < 57 && "Opcode too big???");
unsigned Opcode = I.getOpcode();
unsigned NumOperands = I.getNumOperands();
// Encode 'tail call' as 61, 'volatile load' as 62, and 'volatile store' as
// 63.
if (const CallInst *CI = dyn_cast<CallInst>(&I)) {
if (CI->getCallingConv() == CallingConv::C) {
if (CI->isTailCall())
Opcode = 61; // CCC + Tail Call
else
; // Opcode = Instruction::Call
} else if (CI->getCallingConv() == CallingConv::Fast) {
if (CI->isTailCall())
Opcode = 59; // FastCC + TailCall
else
Opcode = 60; // FastCC + Not Tail Call
} else {
Opcode = 58; // Call escape sequence.
}
} else if (isa<LoadInst>(I) && cast<LoadInst>(I).isVolatile()) {
Opcode = 62;
} else 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 = Table.getTypeSlot(Ty);
// 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) {
unsigned Slot = Table.getSlot(I.getOperand(i));
if (Slot > MaxOpSlot) MaxOpSlot = Slot;
Slots[i] = 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.getTypeSlot(I.getType());
if (Slots[1] > MaxOpSlot) MaxOpSlot = Slots[1];
NumOperands++;
} else if (const AllocationInst *AI = dyn_cast<AllocationInst>(&I)) {
assert(NumOperands == 1 && "Bogus allocation!");
if (AI->getAlignment()) {
Slots[1] = Log2_32(AI->getAlignment())+1;
if (Slots[1] > MaxOpSlot) MaxOpSlot = Slots[1];
NumOperands = 2;
}
} else if (isa<ICmpInst>(I) || isa<FCmpInst>(I)) {
// We need to encode the compare instruction's predicate as the third
// operand. Its not really a slot, but we don't want to break the
// instruction format for these instructions.
NumOperands++;
assert(NumOperands == 3 && "CmpInst with wrong number of operands?");
Slots[2] = unsigned(cast<CmpInst>(&I)->getPredicate());
if (Slots[2] > MaxOpSlot)
MaxOpSlot = Slots[2];
} 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)) {
// These should be either 32-bits or 64-bits, however, with bit
// accurate types we just distinguish between less than or equal to
// 32-bits or greater than 32-bits.
unsigned BitWidth =
cast<IntegerType>(GEP->getOperand(Idx)->getType())->getBitWidth();
assert(BitWidth == 32 || BitWidth == 64 &&
"Invalid bitwidth for GEP index");
unsigned IdxId = BitWidth == 32 ? 0 : 1;
Slots[Idx] = (Slots[Idx] << 1) | IdxId;
if (Slots[Idx] > MaxOpSlot) MaxOpSlot = Slots[Idx];
}
} else if (Opcode == 58) {
// If this is the escape sequence for call, emit the tailcall/cc info.
const CallInst &CI = cast<CallInst>(I);
++NumOperands;
if (NumOperands <= 3) {
Slots[NumOperands-1] =
(CI.getCallingConv() << 1)|unsigned(CI.isTailCall());
if (Slots[NumOperands-1] > MaxOpSlot)
MaxOpSlot = Slots[NumOperands-1];
}
} else if (isa<InvokeInst>(I)) {
// Invoke escape seq has at least 4 operands to encode.
++NumOperands;
}
// 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);
// Output the version identifier
output_vbr(BCVersionNum);
// 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();
// 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);
// Output the symbole table for types
outputTypeSymbolTable(M->getTypeSymbolTable());
// Output the symbol table for values
outputValueSymbolTable(M->getValueSymbolTable());
}
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]) ||
isa<InlineAsm>(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.
// Put out type header: [num entries][type id number]
//
output_vbr(NC);
// Put out the Type ID Number.
output_typeid(Table.getTypeSlot(Plane.front()->getType()));
for (unsigned i = ValNo; i < ValNo+NC; ++i) {
const Value *V = Plane[i];
if (const Constant *C = dyn_cast<Constant>(V))
outputConstant(C);
else
outputInlineAsm(cast<InlineAsm>(V));
}
}
static inline bool hasNullValue(const Type *Ty) {
return Ty != Type::LabelTy && Ty != Type::VoidTy && !isa<OpaqueType>(Ty);
}
void BytecodeWriter::outputConstants() {
BytecodeBlock CPool(BytecodeFormat::ConstantPoolBlockID, *this,
true /* Elide block if empty */);
unsigned NumPlanes = Table.getNumPlanes();
// 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 (hasNullValue(Plane[0]->getType())) {
// Skip zero initializer
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;
case GlobalValue::DLLImportLinkage: return 5;
case GlobalValue::DLLExportLinkage: return 6;
case GlobalValue::ExternalWeakLinkage: return 7;
}
}
static unsigned getEncodedVisibility(const GlobalValue *GV) {
switch (GV->getVisibility()) {
default: assert(0 && "Invalid visibility!");
case GlobalValue::DefaultVisibility: return 0;
case GlobalValue::HiddenVisibility: return 1;
}
}
void BytecodeWriter::outputModuleInfoBlock(const Module *M) {
BytecodeBlock ModuleInfoBlock(BytecodeFormat::ModuleGlobalInfoBlockID, *this);
// Give numbers to sections as we encounter them.
unsigned SectionIDCounter = 0;
std::vector<std::string> SectionNames;
std::map<std::string, unsigned> SectionID;
// Output the types for the global variables in the module...
for (Module::const_global_iterator I = M->global_begin(),
End = M->global_end(); I != End; ++I) {
unsigned Slot = Table.getTypeSlot(I->getType());
assert((I->hasInitializer() || !I->hasInternalLinkage()) &&
"Global must have an initializer or have external linkage!");
// Fields: bit0 = isConstant, bit1 = hasInitializer, bit2-4=Linkage,
// bit5+ = Slot # for type.
bool HasExtensionWord = (I->getAlignment() != 0) ||
I->hasSection() ||
(I->getVisibility() != GlobalValue::DefaultVisibility);
// If we need to use the extension byte, set linkage=3(internal) and
// initializer = 0 (impossible!).
if (!HasExtensionWord) {
unsigned oSlot = (Slot << 5) | (getEncodedLinkage(I) << 2) |
(I->hasInitializer() << 1) | (unsigned)I->isConstant();
output_vbr(oSlot);
} else {
unsigned oSlot = (Slot << 5) | (3 << 2) |
(0 << 1) | (unsigned)I->isConstant();
output_vbr(oSlot);
// The extension word has this format: bit 0 = has initializer, bit 1-3 =
// linkage, bit 4-8 = alignment (log2), bit 9 = has SectionID,
// bits 10-12 = visibility, bits 13+ = future use.
unsigned ExtWord = (unsigned)I->hasInitializer() |
(getEncodedLinkage(I) << 1) |
((Log2_32(I->getAlignment())+1) << 4) |
((unsigned)I->hasSection() << 9) |
(getEncodedVisibility(I) << 10);
output_vbr(ExtWord);
if (I->hasSection()) {
// Give section names unique ID's.
unsigned &Entry = SectionID[I->getSection()];
if (Entry == 0) {
Entry = ++SectionIDCounter;
SectionNames.push_back(I->getSection());
}
output_vbr(Entry);
}
}
// If we have an initializer, output it now.
if (I->hasInitializer())
output_vbr(Table.getSlot((Value*)I->getInitializer()));
}
output_typeid(Table.getTypeSlot(Type::VoidTy));
// Output the types of the functions in this module.
for (Module::const_iterator I = M->begin(), End = M->end(); I != End; ++I) {
unsigned Slot = Table.getTypeSlot(I->getType());
assert(((Slot << 6) >> 6) == Slot && "Slot # too big!");
unsigned CC = I->getCallingConv()+1;
unsigned ID = (Slot << 5) | (CC & 15);
if (I->isDeclaration()) // If external, we don't have an FunctionInfo block.
ID |= 1 << 4;
if (I->getAlignment() || I->hasSection() || (CC & ~15) != 0 ||
(I->isDeclaration() && I->hasDLLImportLinkage()) ||
(I->isDeclaration() && I->hasExternalWeakLinkage())
)
ID |= 1 << 31; // Do we need an extension word?
output_vbr(ID);
if (ID & (1 << 31)) {
// Extension byte: bits 0-4 = alignment, bits 5-9 = top nibble of calling
// convention, bit 10 = hasSectionID., bits 11-12 = external linkage type
unsigned extLinkage = 0;
if (I->isDeclaration()) {
if (I->hasDLLImportLinkage()) {
extLinkage = 1;
} else if (I->hasExternalWeakLinkage()) {
extLinkage = 2;
}
}
ID = (Log2_32(I->getAlignment())+1) | ((CC >> 4) << 5) |
(I->hasSection() << 10) |
((extLinkage & 3) << 11);
output_vbr(ID);
// Give section names unique ID's.
if (I->hasSection()) {
unsigned &Entry = SectionID[I->getSection()];
if (Entry == 0) {
Entry = ++SectionIDCounter;
SectionNames.push_back(I->getSection());
}
output_vbr(Entry);
}
}
}
output_vbr(Table.getTypeSlot(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());
// Output the data layout from the module
output(M->getDataLayout());
// Emit the table of section names.
output_vbr((unsigned)SectionNames.size());
for (unsigned i = 0, e = SectionNames.size(); i != e; ++i)
output(SectionNames[i]);
// Output the inline asm string.
output(M->getModuleInlineAsm());
}
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->isDeclaration()) return;
BytecodeBlock FunctionBlock(BytecodeFormat::FunctionBlockID, *this);
unsigned rWord = (getEncodedVisibility(F) << 16) | getEncodedLinkage(F);
output_vbr(rWord);
// Get slot information about the function...
Table.incorporateFunction(F);
// Output all of the instructions in the body of the function
outputInstructions(F);
// If needed, output the symbol table for the function...
outputValueSymbolTable(F->getValueSymbolTable());
Table.purgeFunction();
}
void BytecodeWriter::outputTypeSymbolTable(const TypeSymbolTable &TST) {
// Do not output the block for an empty symbol table, it just wastes
// space!
if (TST.empty()) return;
// Create a header for the symbol table
BytecodeBlock SymTabBlock(BytecodeFormat::TypeSymbolTableBlockID, *this,
true/*ElideIfEmpty*/);
// Write the number of types
output_vbr(TST.size());
// Write each of the types
for (TypeSymbolTable::const_iterator TI = TST.begin(), TE = TST.end();
TI != TE; ++TI) {
// Symtab entry:[def slot #][name]
output_typeid(Table.getTypeSlot(TI->second));
output(TI->first);
}
}
void BytecodeWriter::outputValueSymbolTable(const ValueSymbolTable &VST) {
// Do not output the Bytecode block for an empty symbol table, it just wastes
// space!
if (VST.empty()) return;
BytecodeBlock SymTabBlock(BytecodeFormat::ValueSymbolTableBlockID, *this,
true/*ElideIfEmpty*/);
// Organize the symbol table by type
typedef std::pair<std::string, const Value*> PlaneMapEntry;
typedef std::vector<PlaneMapEntry> PlaneMapVector;
typedef std::map<const Type*, PlaneMapVector > PlaneMap;
PlaneMap Planes;
for (ValueSymbolTable::const_iterator SI = VST.begin(), SE = VST.end();
SI != SE; ++SI)
Planes[SI->second->getType()].push_back(
std::make_pair(SI->first,SI->second));
for (PlaneMap::const_iterator PI = Planes.begin(), PE = Planes.end();
PI != PE; ++PI) {
PlaneMapVector::const_iterator I = PI->second.begin();
PlaneMapVector::const_iterator End = PI->second.end();
if (I == End) continue; // Don't mess with an absent type...
// Write the number of values in this plane
output_vbr((unsigned)PI->second.size());
// Write the slot number of the type for this plane
output_typeid(Table.getTypeSlot(PI->first));
// Write each of the values in this plane
for (; I != End; ++I) {
// Symtab entry: [def slot #][name]
output_vbr(Table.getSlot(I->second));
output(I->first);
}
}
}
void llvm::WriteBytecodeToFile(const Module *M, OStream &Out,
bool compress) {
assert(M && "You can't write a null module!!");
// Make sure that std::cout is put into binary mode for systems
// that care.
if (Out == cout)
sys::Program::ChangeStdoutToBinary();
// 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.stream()->write(compressed_magic,4);
// Compress everything after the magic number (which we altered)
Compressor::compressToStream(
(char*)(FirstByte+4), // Skip the magic number
Buffer.size()-4, // Skip the magic number
*Out.stream() // Where to write compressed data
);
} else {
// We're not compressing, so just write the entire block.
Out.stream()->write((char*)FirstByte, Buffer.size());
}
// make sure it hits disk now
Out.stream()->flush();
}
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