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llvm-project/llvm/lib/Bytecode/Reader/ConstantReader.cpp

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//===- ReadConst.cpp - Code to constants and constant pools ---------------===//
//
// This file implements functionality to deserialize constants and entire
// constant pools.
//
// Note that this library should be as fast as possible, reentrant, and
// thread-safe!!
//
//===----------------------------------------------------------------------===//
#include "ReaderInternals.h"
#include "llvm/Module.h"
#include "llvm/Constants.h"
#include <algorithm>
const Type *BytecodeParser::parseTypeConstant(const unsigned char *&Buf,
const unsigned char *EndBuf) {
unsigned PrimType;
if (read_vbr(Buf, EndBuf, PrimType)) throw Error_readvbr;
const Type *Val = 0;
if ((Val = Type::getPrimitiveType((Type::PrimitiveID)PrimType)))
return Val;
switch (PrimType) {
case Type::FunctionTyID: {
unsigned Typ;
if (read_vbr(Buf, EndBuf, Typ)) return Val;
const Type *RetType = getType(Typ);
unsigned NumParams;
if (read_vbr(Buf, EndBuf, NumParams)) return Val;
std::vector<const Type*> Params;
while (NumParams--) {
if (read_vbr(Buf, EndBuf, Typ)) return Val;
Params.push_back(getType(Typ));
}
bool isVarArg = Params.size() && Params.back() == Type::VoidTy;
if (isVarArg) Params.pop_back();
return FunctionType::get(RetType, Params, isVarArg);
}
case Type::ArrayTyID: {
unsigned ElTyp;
if (read_vbr(Buf, EndBuf, ElTyp)) return Val;
const Type *ElementType = getType(ElTyp);
unsigned NumElements;
if (read_vbr(Buf, EndBuf, NumElements)) return Val;
BCR_TRACE(5, "Array Type Constant #" << ElTyp << " size="
<< NumElements << "\n");
return ArrayType::get(ElementType, NumElements);
}
case Type::StructTyID: {
unsigned Typ;
std::vector<const Type*> Elements;
if (read_vbr(Buf, EndBuf, Typ)) return Val;
while (Typ) { // List is terminated by void/0 typeid
Elements.push_back(getType(Typ));
if (read_vbr(Buf, EndBuf, Typ)) return Val;
}
return StructType::get(Elements);
}
case Type::PointerTyID: {
unsigned ElTyp;
if (read_vbr(Buf, EndBuf, ElTyp)) return Val;
BCR_TRACE(5, "Pointer Type Constant #" << ElTyp << "\n");
return PointerType::get(getType(ElTyp));
}
case Type::OpaqueTyID: {
return OpaqueType::get();
}
default:
std::cerr << __FILE__ << ":" << __LINE__
<< ": Don't know how to deserialize"
<< " primitive Type " << PrimType << "\n";
return Val;
}
}
// parseTypeConstants - We have to use this weird code to handle recursive
// types. We know that recursive types will only reference the current slab of
// values in the type plane, but they can forward reference types before they
// have been read. For example, Type #0 might be '{ Ty#1 }' and Type #1 might
// be 'Ty#0*'. When reading Type #0, type number one doesn't exist. To fix
// this ugly problem, we pessimistically insert an opaque type for each type we
// are about to read. This means that forward references will resolve to
// something and when we reread the type later, we can replace the opaque type
// with a new resolved concrete type.
//
void debug_type_tables();
void BytecodeParser::parseTypeConstants(const unsigned char *&Buf,
const unsigned char *EndBuf,
TypeValuesListTy &Tab,
unsigned NumEntries) {
assert(Tab.size() == 0 && "should not have read type constants in before!");
// Insert a bunch of opaque types to be resolved later...
for (unsigned i = 0; i < NumEntries; ++i)
Tab.push_back(OpaqueType::get());
// Loop through reading all of the types. Forward types will make use of the
// opaque types just inserted.
//
for (unsigned i = 0; i < NumEntries; ++i) {
const Type *NewTy = parseTypeConstant(Buf, EndBuf), *OldTy = Tab[i].get();
if (NewTy == 0) throw std::string("Parsed invalid type.");
BCR_TRACE(4, "#" << i << ": Read Type Constant: '" << NewTy <<
"' Replacing: " << OldTy << "\n");
// Don't insertValue the new type... instead we want to replace the opaque
// type with the new concrete value...
//
// Refine the abstract type to the new type. This causes all uses of the
// abstract type to use the newty. This also will cause the opaque type
// to be deleted...
//
((DerivedType*)Tab[i].get())->refineAbstractTypeTo(NewTy);
// This should have replace the old opaque type with the new type in the
// value table... or with a preexisting type that was already in the system
assert(Tab[i] != OldTy && "refineAbstractType didn't work!");
}
BCR_TRACE(5, "Resulting types:\n");
for (unsigned i = 0; i < NumEntries; ++i) {
BCR_TRACE(5, (void*)Tab[i].get() << " - " << Tab[i].get() << "\n");
}
debug_type_tables();
}
Constant *BytecodeParser::parseConstantValue(const unsigned char *&Buf,
const unsigned char *EndBuf,
const Type *Ty) {
// We must check for a ConstantExpr before switching by type because
// a ConstantExpr can be of any type, and has no explicit value.
//
unsigned isExprNumArgs; // 0 if not expr; numArgs if is expr
if (read_vbr(Buf, EndBuf, isExprNumArgs)) throw Error_readvbr;
if (isExprNumArgs) {
// FIXME: Encoding of constant exprs could be much more compact!
unsigned Opcode;
std::vector<Constant*> ArgVec;
ArgVec.reserve(isExprNumArgs);
if (read_vbr(Buf, EndBuf, Opcode)) throw Error_readvbr;
// Read the slot number and types of each of the arguments
for (unsigned i = 0; i != isExprNumArgs; ++i) {
unsigned ArgValSlot, ArgTypeSlot;
if (read_vbr(Buf, EndBuf, ArgValSlot)) throw Error_readvbr;
if (read_vbr(Buf, EndBuf, ArgTypeSlot)) throw Error_readvbr;
const Type *ArgTy = getType(ArgTypeSlot);
BCR_TRACE(4, "CE Arg " << i << ": Type: '" << *ArgTy << "' slot: "
<< ArgValSlot << "\n");
// Get the arg value from its slot if it exists, otherwise a placeholder
ArgVec.push_back(getConstantValue(ArgTy, ArgValSlot));
}
// Construct a ConstantExpr of the appropriate kind
if (isExprNumArgs == 1) { // All one-operand expressions
assert(Opcode == Instruction::Cast);
return ConstantExpr::getCast(ArgVec[0], Ty);
} else if (Opcode == Instruction::GetElementPtr) { // GetElementPtr
std::vector<Constant*> IdxList(ArgVec.begin()+1, ArgVec.end());
return ConstantExpr::getGetElementPtr(ArgVec[0], IdxList);
} else { // All other 2-operand expressions
return ConstantExpr::get(Opcode, ArgVec[0], ArgVec[1]);
}
}
// Ok, not an ConstantExpr. We now know how to read the given type...
switch (Ty->getPrimitiveID()) {
case Type::BoolTyID: {
unsigned Val;
if (read_vbr(Buf, EndBuf, Val)) throw Error_readvbr;
if (Val != 0 && Val != 1) throw std::string("Invalid boolean value read.");
return ConstantBool::get(Val == 1);
}
case Type::UByteTyID: // Unsigned integer types...
case Type::UShortTyID:
case Type::UIntTyID: {
unsigned Val;
if (read_vbr(Buf, EndBuf, Val)) throw Error_readvbr;
if (!ConstantUInt::isValueValidForType(Ty, Val))
throw std::string("Invalid unsigned byte/short/int read.");
return ConstantUInt::get(Ty, Val);
}
case Type::ULongTyID: {
uint64_t Val;
if (read_vbr(Buf, EndBuf, Val)) throw Error_readvbr;
return ConstantUInt::get(Ty, Val);
}
case Type::SByteTyID: // Signed integer types...
case Type::ShortTyID:
case Type::IntTyID: {
case Type::LongTyID:
int64_t Val;
if (read_vbr(Buf, EndBuf, Val)) throw Error_readvbr;
if (!ConstantSInt::isValueValidForType(Ty, Val))
throw std::string("Invalid signed byte/short/int/long read.");
return ConstantSInt::get(Ty, Val);
}
case Type::FloatTyID: {
float F;
if (input_data(Buf, EndBuf, &F, &F+1)) throw Error_inputdata;
return ConstantFP::get(Ty, F);
}
case Type::DoubleTyID: {
double Val;
if (input_data(Buf, EndBuf, &Val, &Val+1)) throw Error_inputdata;
return ConstantFP::get(Ty, Val);
}
case Type::TypeTyID:
throw std::string("Type constants shouldn't live in constant table!");
case Type::ArrayTyID: {
const ArrayType *AT = cast<ArrayType>(Ty);
unsigned NumElements = AT->getNumElements();
std::vector<Constant*> Elements;
while (NumElements--) { // Read all of the elements of the constant.
unsigned Slot;
if (read_vbr(Buf, EndBuf, Slot)) throw Error_readvbr;
Elements.push_back(getConstantValue(AT->getElementType(), Slot));
}
return ConstantArray::get(AT, Elements);
}
case Type::StructTyID: {
const StructType *ST = cast<StructType>(Ty);
const StructType::ElementTypes &ET = ST->getElementTypes();
std::vector<Constant *> Elements;
for (unsigned i = 0; i < ET.size(); ++i) {
unsigned Slot;
if (read_vbr(Buf, EndBuf, Slot)) throw Error_readvbr;
Elements.push_back(getConstantValue(ET[i], Slot));
}
return ConstantStruct::get(ST, Elements);
}
case Type::PointerTyID: {
const PointerType *PT = cast<PointerType>(Ty);
unsigned SubClass;
if (HasImplicitZeroInitializer)
SubClass = 1;
else
if (read_vbr(Buf, EndBuf, SubClass)) throw Error_readvbr;
switch (SubClass) {
case 0: // ConstantPointerNull value...
return ConstantPointerNull::get(PT);
case 1: { // ConstantPointerRef value...
unsigned Slot;
if (read_vbr(Buf, EndBuf, Slot)) throw Error_readvbr;
BCR_TRACE(4, "CPR: Type: '" << Ty << "' slot: " << Slot << "\n");
// Check to see if we have already read this global variable...
Value *Val = getValue(PT, Slot, false);
GlobalValue *GV;
if (Val) {
if (!(GV = dyn_cast<GlobalValue>(Val)))
throw std::string("Value of ConstantPointerRef not in ValueTable!");
BCR_TRACE(5, "Value Found in ValueTable!\n");
} else if (RevisionNum > 0) {
// Revision #0 could have forward references to globals that were weird.
// We got rid of this in subsequent revs.
throw std::string("Forward references to globals not allowed.");
} else { // Nope... find or create a forward ref. for it
GlobalRefsType::iterator I = GlobalRefs.find(std::make_pair(PT, Slot));
if (I != GlobalRefs.end()) {
BCR_TRACE(5, "Previous forward ref found!\n");
GV = cast<GlobalValue>(I->second);
} else {
BCR_TRACE(5, "Creating new forward ref to a global variable!\n");
// Create a placeholder for the global variable reference...
GlobalVariable *GVar =
new GlobalVariable(PT->getElementType(), false,
GlobalValue::InternalLinkage);
// Keep track of the fact that we have a forward ref to recycle it
GlobalRefs.insert(std::make_pair(std::make_pair(PT, Slot), GVar));
// Must temporarily push this value into the module table...
TheModule->getGlobalList().push_back(GVar);
GV = GVar;
}
}
return ConstantPointerRef::get(GV);
}
default:
BCR_TRACE(5, "UNKNOWN Pointer Constant Type!\n");
throw std::string("Unknown pointer constant type.");
}
}
default:
throw std::string("Don't know how to deserialize constant value of type '"+
Ty->getDescription());
}
}
void BytecodeParser::ParseGlobalTypes(const unsigned char *&Buf,
const unsigned char *EndBuf) {
ValueTable T;
ParseConstantPool(Buf, EndBuf, T, ModuleTypeValues);
}
void BytecodeParser::ParseConstantPool(const unsigned char *&Buf,
const unsigned char *EndBuf,
ValueTable &Tab,
TypeValuesListTy &TypeTab) {
while (Buf < EndBuf) {
unsigned NumEntries, Typ;
if (read_vbr(Buf, EndBuf, NumEntries) ||
read_vbr(Buf, EndBuf, Typ)) throw Error_readvbr;
if (Typ == Type::TypeTyID) {
BCR_TRACE(3, "Type: 'type' NumEntries: " << NumEntries << "\n");
parseTypeConstants(Buf, EndBuf, TypeTab, NumEntries);
} else {
const Type *Ty = getType(Typ);
BCR_TRACE(3, "Type: '" << *Ty << "' NumEntries: " << NumEntries << "\n");
for (unsigned i = 0; i < NumEntries; ++i) {
Constant *C = parseConstantValue(Buf, EndBuf, Ty);
assert(C && "parseConstantValue returned NULL!");
BCR_TRACE(4, "Read Constant: '" << *C << "'\n");
unsigned Slot = insertValue(C, Typ, Tab);
// If we are reading a function constant table, make sure that we adjust
// the slot number to be the real global constant number.
//
if (&Tab != &ModuleValues && Typ < ModuleValues.size())
Slot += ModuleValues[Typ]->size();
ResolveReferencesToValue(C, Slot);
}
}
}
if (Buf > EndBuf) throw std::string("Read past end of buffer.");
}
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