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522b7b104c
llvm-6502/lib/Bitcode/Reader/BitcodeReader.cpp
Chris Lattner 522b7b104c implement support for reading aggregate constants, including handling forward 
constant references, etc.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@36391 91177308-0d34-0410-b5e6-96231b3b80d8
2007-04-24 05:48:56 +00:00

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//===- BitcodeReader.cpp - Internal BitcodeReader implementation ----------===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by Chris Lattner and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This header defines the BitcodeReader class.
//
//===----------------------------------------------------------------------===//
#include "BitcodeReader.h"
#include "llvm/Bitcode/BitstreamReader.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Module.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/Support/MathExtras.h"
using namespace llvm;
/// ConvertToString - Convert a string from a record into an std::string, return
/// true on failure.
template<typename StrTy>
static bool ConvertToString(SmallVector<uint64_t, 64> &Record, unsigned Idx,
StrTy &Result) {
if (Record.size() < Idx+1 || Record.size() < Record[Idx]+Idx+1)
return true;
for (unsigned i = 0, e = Record[Idx]; i != e; ++i)
Result += (char)Record[Idx+i+1];
return false;
}
static GlobalValue::LinkageTypes GetDecodedLinkage(unsigned Val) {
switch (Val) {
default: // Map unknown/new linkages to external
case 0: return GlobalValue::ExternalLinkage;
case 1: return GlobalValue::WeakLinkage;
case 2: return GlobalValue::AppendingLinkage;
case 3: return GlobalValue::InternalLinkage;
case 4: return GlobalValue::LinkOnceLinkage;
case 5: return GlobalValue::DLLImportLinkage;
case 6: return GlobalValue::DLLExportLinkage;
case 7: return GlobalValue::ExternalWeakLinkage;
}
}
static GlobalValue::VisibilityTypes GetDecodedVisibility(unsigned Val) {
switch (Val) {
default: // Map unknown visibilities to default.
case 0: return GlobalValue::DefaultVisibility;
case 1: return GlobalValue::HiddenVisibility;
}
}
namespace {
/// @brief A class for maintaining the slot number definition
/// as a placeholder for the actual definition for forward constants defs.
class ConstantPlaceHolder : public ConstantExpr {
ConstantPlaceHolder(); // DO NOT IMPLEMENT
void operator=(const ConstantPlaceHolder &); // DO NOT IMPLEMENT
public:
Use Op;
ConstantPlaceHolder(const Type *Ty)
: ConstantExpr(Ty, Instruction::UserOp1, &Op, 1),
Op(UndefValue::get(Type::Int32Ty), this) {
}
};
}
Constant *BitcodeReaderValueList::getConstantFwdRef(unsigned Idx,
const Type *Ty) {
if (Idx >= size()) {
// Insert a bunch of null values.
Uses.resize(Idx+1);
OperandList = &Uses[0];
NumOperands = Idx+1;
}
if (Uses[Idx])
return cast<Constant>(getOperand(Idx));
// Create and return a placeholder, which will later be RAUW'd.
Constant *C = new ConstantPlaceHolder(Ty);
Uses[Idx].init(C, this);
return C;
}
const Type *BitcodeReader::getTypeByID(unsigned ID, bool isTypeTable) {
// If the TypeID is in range, return it.
if (ID < TypeList.size())
return TypeList[ID].get();
if (!isTypeTable) return 0;
// The type table allows forward references. Push as many Opaque types as
// needed to get up to ID.
while (TypeList.size() <= ID)
TypeList.push_back(OpaqueType::get());
return TypeList.back().get();
}
bool BitcodeReader::ParseTypeTable(BitstreamReader &Stream) {
if (Stream.EnterSubBlock())
return Error("Malformed block record");
if (!TypeList.empty())
return Error("Multiple TYPE_BLOCKs found!");
SmallVector<uint64_t, 64> Record;
unsigned NumRecords = 0;
// Read all the records for this type table.
while (1) {
unsigned Code = Stream.ReadCode();
if (Code == bitc::END_BLOCK) {
if (NumRecords != TypeList.size())
return Error("Invalid type forward reference in TYPE_BLOCK");
return Stream.ReadBlockEnd();
}
if (Code == bitc::ENTER_SUBBLOCK) {
// No known subblocks, always skip them.
Stream.ReadSubBlockID();
if (Stream.SkipBlock())
return Error("Malformed block record");
continue;
}
if (Code == bitc::DEFINE_ABBREV) {
Stream.ReadAbbrevRecord();
continue;
}
// Read a record.
Record.clear();
const Type *ResultTy = 0;
switch (Stream.ReadRecord(Code, Record)) {
default: // Default behavior: unknown type.
ResultTy = 0;
break;
case bitc::TYPE_CODE_NUMENTRY: // TYPE_CODE_NUMENTRY: [numentries]
// TYPE_CODE_NUMENTRY contains a count of the number of types in the
// type list. This allows us to reserve space.
if (Record.size() < 1)
return Error("Invalid TYPE_CODE_NUMENTRY record");
TypeList.reserve(Record[0]);
continue;
case bitc::TYPE_CODE_META: // TYPE_CODE_META: [metacode]...
// No metadata supported yet.
if (Record.size() < 1)
return Error("Invalid TYPE_CODE_META record");
continue;
case bitc::TYPE_CODE_VOID: // VOID
ResultTy = Type::VoidTy;
break;
case bitc::TYPE_CODE_FLOAT: // FLOAT
ResultTy = Type::FloatTy;
break;
case bitc::TYPE_CODE_DOUBLE: // DOUBLE
ResultTy = Type::DoubleTy;
break;
case bitc::TYPE_CODE_LABEL: // LABEL
ResultTy = Type::LabelTy;
break;
case bitc::TYPE_CODE_OPAQUE: // OPAQUE
ResultTy = 0;
break;
case bitc::TYPE_CODE_INTEGER: // INTEGER: [width]
if (Record.size() < 1)
return Error("Invalid Integer type record");
ResultTy = IntegerType::get(Record[0]);
break;
case bitc::TYPE_CODE_POINTER: // POINTER: [pointee type]
if (Record.size() < 1)
return Error("Invalid POINTER type record");
ResultTy = PointerType::get(getTypeByID(Record[0], true));
break;
case bitc::TYPE_CODE_FUNCTION: {
// FUNCTION: [vararg, retty, #pararms, paramty N]
if (Record.size() < 3 || Record.size() < Record[2]+3)
return Error("Invalid FUNCTION type record");
std::vector<const Type*> ArgTys;
for (unsigned i = 0, e = Record[2]; i != e; ++i)
ArgTys.push_back(getTypeByID(Record[3+i], true));
// FIXME: PARAM TYS.
ResultTy = FunctionType::get(getTypeByID(Record[1], true), ArgTys,
Record[0]);
break;
}
case bitc::TYPE_CODE_STRUCT: { // STRUCT: [ispacked, #elts, eltty x N]
if (Record.size() < 2 || Record.size() < Record[1]+2)
return Error("Invalid STRUCT type record");
std::vector<const Type*> EltTys;
for (unsigned i = 0, e = Record[1]; i != e; ++i)
EltTys.push_back(getTypeByID(Record[2+i], true));
ResultTy = StructType::get(EltTys, Record[0]);
break;
}
case bitc::TYPE_CODE_ARRAY: // ARRAY: [numelts, eltty]
if (Record.size() < 2)
return Error("Invalid ARRAY type record");
ResultTy = ArrayType::get(getTypeByID(Record[1], true), Record[0]);
break;
case bitc::TYPE_CODE_VECTOR: // VECTOR: [numelts, eltty]
if (Record.size() < 2)
return Error("Invalid VECTOR type record");
ResultTy = VectorType::get(getTypeByID(Record[1], true), Record[0]);
break;
}
if (NumRecords == TypeList.size()) {
// If this is a new type slot, just append it.
TypeList.push_back(ResultTy ? ResultTy : OpaqueType::get());
++NumRecords;
} else if (ResultTy == 0) {
// Otherwise, this was forward referenced, so an opaque type was created,
// but the result type is actually just an opaque. Leave the one we
// created previously.
++NumRecords;
} else {
// Otherwise, this was forward referenced, so an opaque type was created.
// Resolve the opaque type to the real type now.
assert(NumRecords < TypeList.size() && "Typelist imbalance");
const OpaqueType *OldTy = cast<OpaqueType>(TypeList[NumRecords++].get());
// Don't directly push the new type on the Tab. Instead we want to replace
// the opaque type we previously inserted with the new concrete value. The
// refinement from the abstract (opaque) type to the new type causes all
// uses of the abstract type to use the concrete type (NewTy). This will
// also cause the opaque type to be deleted.
const_cast<OpaqueType*>(OldTy)->refineAbstractTypeTo(ResultTy);
// This should have replaced the old opaque type with the new type in the
// value table... or with a preexisting type that was already in the
// system. Let's just make sure it did.
assert(TypeList[NumRecords-1].get() != OldTy &&
"refineAbstractType didn't work!");
}
}
}
bool BitcodeReader::ParseTypeSymbolTable(BitstreamReader &Stream) {
if (Stream.EnterSubBlock())
return Error("Malformed block record");
SmallVector<uint64_t, 64> Record;
// Read all the records for this type table.
std::string TypeName;
while (1) {
unsigned Code = Stream.ReadCode();
if (Code == bitc::END_BLOCK)
return Stream.ReadBlockEnd();
if (Code == bitc::ENTER_SUBBLOCK) {
// No known subblocks, always skip them.
Stream.ReadSubBlockID();
if (Stream.SkipBlock())
return Error("Malformed block record");
continue;
}
if (Code == bitc::DEFINE_ABBREV) {
Stream.ReadAbbrevRecord();
continue;
}
// Read a record.
Record.clear();
switch (Stream.ReadRecord(Code, Record)) {
default: // Default behavior: unknown type.
break;
case bitc::TST_CODE_ENTRY: // TST_ENTRY: [typeid, namelen, namechar x N]
if (ConvertToString(Record, 1, TypeName))
return Error("Invalid TST_ENTRY record");
unsigned TypeID = Record[0];
if (TypeID >= TypeList.size())
return Error("Invalid Type ID in TST_ENTRY record");
TheModule->addTypeName(TypeName, TypeList[TypeID].get());
TypeName.clear();
break;
}
}
}
bool BitcodeReader::ParseValueSymbolTable(BitstreamReader &Stream) {
if (Stream.EnterSubBlock())
return Error("Malformed block record");
SmallVector<uint64_t, 64> Record;
// Read all the records for this value table.
SmallString<128> ValueName;
while (1) {
unsigned Code = Stream.ReadCode();
if (Code == bitc::END_BLOCK)
return Stream.ReadBlockEnd();
if (Code == bitc::ENTER_SUBBLOCK) {
// No known subblocks, always skip them.
Stream.ReadSubBlockID();
if (Stream.SkipBlock())
return Error("Malformed block record");
continue;
}
if (Code == bitc::DEFINE_ABBREV) {
Stream.ReadAbbrevRecord();
continue;
}
// Read a record.
Record.clear();
switch (Stream.ReadRecord(Code, Record)) {
default: // Default behavior: unknown type.
break;
case bitc::TST_CODE_ENTRY: // VST_ENTRY: [valueid, namelen, namechar x N]
if (ConvertToString(Record, 1, ValueName))
return Error("Invalid TST_ENTRY record");
unsigned ValueID = Record[0];
if (ValueID >= ValueList.size())
return Error("Invalid Value ID in VST_ENTRY record");
Value *V = ValueList[ValueID];
V->setName(&ValueName[0], ValueName.size());
ValueName.clear();
break;
}
}
}
/// DecodeSignRotatedValue - Decode a signed value stored with the sign bit in
/// the LSB for dense VBR encoding.
static uint64_t DecodeSignRotatedValue(uint64_t V) {
if ((V & 1) == 0)
return V >> 1;
if (V != 1)
return -(V >> 1);
// There is no such thing as -0 with integers. "-0" really means MININT.
return 1ULL << 63;
}
bool BitcodeReader::ParseConstants(BitstreamReader &Stream) {
if (Stream.EnterSubBlock())
return Error("Malformed block record");
SmallVector<uint64_t, 64> Record;
// Read all the records for this value table.
const Type *CurTy = Type::Int32Ty;
unsigned NextCstNo = ValueList.size();
while (1) {
unsigned Code = Stream.ReadCode();
if (Code == bitc::END_BLOCK) {
// If there are global var inits to process, do so now.
if (!GlobalInits.empty()) {
while (!GlobalInits.empty()) {
unsigned ValID = GlobalInits.back().second;
if (ValID >= ValueList.size())
return Error("Invalid value ID for global var init!");
if (Constant *C = dyn_cast<Constant>(ValueList[ValID]))
GlobalInits.back().first->setInitializer(C);
else
return Error("Global variable initializer is not a constant!");
GlobalInits.pop_back();
}
}
if (NextCstNo != ValueList.size())
return Error("Invalid constant reference!");
return Stream.ReadBlockEnd();
}
if (Code == bitc::ENTER_SUBBLOCK) {
// No known subblocks, always skip them.
Stream.ReadSubBlockID();
if (Stream.SkipBlock())
return Error("Malformed block record");
continue;
}
if (Code == bitc::DEFINE_ABBREV) {
Stream.ReadAbbrevRecord();
continue;
}
// Read a record.
Record.clear();
Value *V = 0;
switch (Stream.ReadRecord(Code, Record)) {
default: // Default behavior: unknown constant
case bitc::CST_CODE_UNDEF: // UNDEF
V = UndefValue::get(CurTy);
break;
case bitc::CST_CODE_SETTYPE: // SETTYPE: [typeid]
if (Record.empty())
return Error("Malformed CST_SETTYPE record");
if (Record[0] >= TypeList.size())
return Error("Invalid Type ID in CST_SETTYPE record");
CurTy = TypeList[Record[0]];
continue; // Skip the ValueList manipulation.
case bitc::CST_CODE_NULL: // NULL
V = Constant::getNullValue(CurTy);
break;
case bitc::CST_CODE_INTEGER: // INTEGER: [intval]
if (!isa<IntegerType>(CurTy) || Record.empty())
return Error("Invalid CST_INTEGER record");
V = ConstantInt::get(CurTy, DecodeSignRotatedValue(Record[0]));
break;
case bitc::CST_CODE_WIDE_INTEGER: {// WIDE_INTEGER: [n, n x intval]
if (!isa<IntegerType>(CurTy) || Record.empty() ||
Record.size() < Record[0]+1)
return Error("Invalid WIDE_INTEGER record");
unsigned NumWords = Record[0];
uint64_t *Data = new uint64_t[NumWords];
for (unsigned i = 0; i != NumWords; ++i)
Data[i] = DecodeSignRotatedValue(Record[i+1]);
V = ConstantInt::get(APInt(cast<IntegerType>(CurTy)->getBitWidth(),
NumWords, Data));
break;
}
case bitc::CST_CODE_FLOAT: // FLOAT: [fpval]
if (Record.empty())
return Error("Invalid FLOAT record");
if (CurTy == Type::FloatTy)
V = ConstantFP::get(CurTy, BitsToFloat(Record[0]));
else if (CurTy == Type::DoubleTy)
V = ConstantFP::get(CurTy, BitsToDouble(Record[0]));
else
V = UndefValue::get(CurTy);
break;
case bitc::CST_CODE_AGGREGATE: {// AGGREGATE: [n, n x value number]
if (Record.empty() || Record.size() < Record[0]+1)
return Error("Invalid CST_AGGREGATE record");
unsigned Size = Record[0];
std::vector<Constant*> Elts;
if (const StructType *STy = dyn_cast<StructType>(CurTy)) {
for (unsigned i = 0; i != Size; ++i)
Elts.push_back(ValueList.getConstantFwdRef(Record[i+1],
STy->getElementType(i)));
V = ConstantStruct::get(STy, Elts);
} else if (const ArrayType *ATy = dyn_cast<ArrayType>(CurTy)) {
const Type *EltTy = ATy->getElementType();
for (unsigned i = 0; i != Size; ++i)
Elts.push_back(ValueList.getConstantFwdRef(Record[i+1], EltTy));
V = ConstantArray::get(ATy, Elts);
} else if (const VectorType *VTy = dyn_cast<VectorType>(CurTy)) {
const Type *EltTy = VTy->getElementType();
for (unsigned i = 0; i != Size; ++i)
Elts.push_back(ValueList.getConstantFwdRef(Record[i+1], EltTy));
V = ConstantVector::get(Elts);
} else {
V = UndefValue::get(CurTy);
}
}
}
if (NextCstNo == ValueList.size())
ValueList.push_back(V);
else if (ValueList[NextCstNo] == 0)
ValueList.initVal(NextCstNo, V);
else {
// If there was a forward reference to this constant,
Value *OldV = ValueList[NextCstNo];
ValueList.setOperand(NextCstNo, V);
OldV->replaceAllUsesWith(V);
delete OldV;
}
++NextCstNo;
}
}
bool BitcodeReader::ParseModule(BitstreamReader &Stream,
const std::string &ModuleID) {
// Reject multiple MODULE_BLOCK's in a single bitstream.
if (TheModule)
return Error("Multiple MODULE_BLOCKs in same stream");
if (Stream.EnterSubBlock())
return Error("Malformed block record");
// Otherwise, create the module.
TheModule = new Module(ModuleID);
SmallVector<uint64_t, 64> Record;
std::vector<std::string> SectionTable;
// Read all the records for this module.
while (!Stream.AtEndOfStream()) {
unsigned Code = Stream.ReadCode();
if (Code == bitc::END_BLOCK) {
if (!GlobalInits.empty())
return Error("Malformed global initializer set");
return Stream.ReadBlockEnd();
}
if (Code == bitc::ENTER_SUBBLOCK) {
switch (Stream.ReadSubBlockID()) {
default: // Skip unknown content.
if (Stream.SkipBlock())
return Error("Malformed block record");
break;
case bitc::TYPE_BLOCK_ID:
if (ParseTypeTable(Stream))
return true;
break;
case bitc::TYPE_SYMTAB_BLOCK_ID:
if (ParseTypeSymbolTable(Stream))
return true;
break;
case bitc::VALUE_SYMTAB_BLOCK_ID:
if (ParseValueSymbolTable(Stream))
return true;
break;
case bitc::CONSTANTS_BLOCK_ID:
if (ParseConstants(Stream))
return true;
break;
}
continue;
}
if (Code == bitc::DEFINE_ABBREV) {
Stream.ReadAbbrevRecord();
continue;
}
// Read a record.
switch (Stream.ReadRecord(Code, Record)) {
default: break; // Default behavior, ignore unknown content.
case bitc::MODULE_CODE_VERSION: // VERSION: [version#]
if (Record.size() < 1)
return Error("Malformed MODULE_CODE_VERSION");
// Only version #0 is supported so far.
if (Record[0] != 0)
return Error("Unknown bitstream version!");
break;
case bitc::MODULE_CODE_TRIPLE: { // TRIPLE: [strlen, strchr x N]
std::string S;
if (ConvertToString(Record, 0, S))
return Error("Invalid MODULE_CODE_TRIPLE record");
TheModule->setTargetTriple(S);
break;
}
case bitc::MODULE_CODE_DATALAYOUT: { // DATALAYOUT: [strlen, strchr x N]
std::string S;
if (ConvertToString(Record, 0, S))
return Error("Invalid MODULE_CODE_DATALAYOUT record");
TheModule->setDataLayout(S);
break;
}
case bitc::MODULE_CODE_ASM: { // ASM: [strlen, strchr x N]
std::string S;
if (ConvertToString(Record, 0, S))
return Error("Invalid MODULE_CODE_ASM record");
TheModule->setModuleInlineAsm(S);
break;
}
case bitc::MODULE_CODE_DEPLIB: { // DEPLIB: [strlen, strchr x N]
std::string S;
if (ConvertToString(Record, 0, S))
return Error("Invalid MODULE_CODE_DEPLIB record");
TheModule->addLibrary(S);
break;
}
case bitc::MODULE_CODE_SECTIONNAME: { // SECTIONNAME: [strlen, strchr x N]
std::string S;
if (ConvertToString(Record, 0, S))
return Error("Invalid MODULE_CODE_SECTIONNAME record");
SectionTable.push_back(S);
break;
}
// GLOBALVAR: [type, isconst, initid,
// linkage, alignment, section, visibility, threadlocal]
case bitc::MODULE_CODE_GLOBALVAR: {
if (Record.size() < 6)
return Error("Invalid MODULE_CODE_GLOBALVAR record");
const Type *Ty = getTypeByID(Record[0]);
if (!isa<PointerType>(Ty))
return Error("Global not a pointer type!");
Ty = cast<PointerType>(Ty)->getElementType();
bool isConstant = Record[1];
GlobalValue::LinkageTypes Linkage = GetDecodedLinkage(Record[3]);
unsigned Alignment = (1 << Record[4]) >> 1;
std::string Section;
if (Record[5]) {
if (Record[5]-1 >= SectionTable.size())
return Error("Invalid section ID");
Section = SectionTable[Record[5]-1];
}
GlobalValue::VisibilityTypes Visibility = GlobalValue::DefaultVisibility;
if (Record.size() >= 6) Visibility = GetDecodedVisibility(Record[6]);
bool isThreadLocal = false;
if (Record.size() >= 7) isThreadLocal = Record[7];
GlobalVariable *NewGV =
new GlobalVariable(Ty, isConstant, Linkage, 0, "", TheModule);
NewGV->setAlignment(Alignment);
if (!Section.empty())
NewGV->setSection(Section);
NewGV->setVisibility(Visibility);
NewGV->setThreadLocal(isThreadLocal);
ValueList.push_back(NewGV);
// Remember which value to use for the global initializer.
if (unsigned InitID = Record[2])
GlobalInits.push_back(std::make_pair(NewGV, InitID-1));
break;
}
// FUNCTION: [type, callingconv, isproto, linkage, alignment, section,
// visibility]
case bitc::MODULE_CODE_FUNCTION: {
if (Record.size() < 7)
return Error("Invalid MODULE_CODE_FUNCTION record");
const Type *Ty = getTypeByID(Record[0]);
if (!isa<PointerType>(Ty))
return Error("Function not a pointer type!");
const FunctionType *FTy =
dyn_cast<FunctionType>(cast<PointerType>(Ty)->getElementType());
if (!FTy)
return Error("Function not a pointer to function type!");
Function *Func = new Function(FTy, GlobalValue::ExternalLinkage,
"", TheModule);
Func->setCallingConv(Record[1]);
Func->setLinkage(GetDecodedLinkage(Record[3]));
Func->setAlignment((1 << Record[4]) >> 1);
if (Record[5]) {
if (Record[5]-1 >= SectionTable.size())
return Error("Invalid section ID");
Func->setSection(SectionTable[Record[5]-1]);
}
Func->setVisibility(GetDecodedVisibility(Record[6]));
ValueList.push_back(Func);
// TODO: remember initializer/global pair for later substitution.
break;
}
}
Record.clear();
}
return Error("Premature end of bitstream");
}
bool BitcodeReader::ParseBitcode(unsigned char *Buf, unsigned Length,
const std::string &ModuleID) {
TheModule = 0;
if (Length & 3)
return Error("Bitcode stream should be a multiple of 4 bytes in length");
BitstreamReader Stream(Buf, Buf+Length);
// Sniff for the signature.
if (Stream.Read(8) != 'B' ||
Stream.Read(8) != 'C' ||
Stream.Read(4) != 0x0 ||
Stream.Read(4) != 0xC ||
Stream.Read(4) != 0xE ||
Stream.Read(4) != 0xD)
return Error("Invalid bitcode signature");
// We expect a number of well-defined blocks, though we don't necessarily
// need to understand them all.
while (!Stream.AtEndOfStream()) {
unsigned Code = Stream.ReadCode();
if (Code != bitc::ENTER_SUBBLOCK)
return Error("Invalid record at top-level");
unsigned BlockID = Stream.ReadSubBlockID();
// We only know the MODULE subblock ID.
if (BlockID == bitc::MODULE_BLOCK_ID) {
if (ParseModule(Stream, ModuleID))
return true;
} else if (Stream.SkipBlock()) {
return Error("Malformed block record");
}
}
return false;
}
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