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Add support for reading ConstantExpr nodes.

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Add class ConstantFwdRefs to resolve forward references to constants
and to globals. (Hmm... this class could be renamed I guess.)


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@2896 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Vikram S. Adve 2002-07-14 23:05:09 +00:00
parent c1e4a813a2
commit c668b7c3ae
2 changed files with 112 additions and 38 deletions
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84
lib/Bytecode/Reader/ConstantReader.cpp
View File

@ -179,6 +179,54 @@ bool BytecodeParser::parseTypeConstants(const uchar *&Buf, const uchar *EndBuf,
bool BytecodeParser::parseConstantValue(const uchar *&Buf, const uchar *EndBuf,
const Type *Ty, Constant *&V) {
// 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)) return failure(true);
if (isExprNumArgs) {
unsigned opCode;
vector<Constant*> argVec;
argVec.reserve(isExprNumArgs);
if (read_vbr(Buf, EndBuf, opCode)) return failure(true);
// 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)) return failure(true);
if (read_vbr(Buf, EndBuf, argTypeSlot)) return failure(true);
const Type *argTy = getType(argTypeSlot);
if (argTy == 0) return failure(true);
BCR_TRACE(4, "CE Arg " << i << ": Type: '" << argTy << "' slot: " << argValSlot << "\n");
// Get the arg value from its slot if it exists, otherwise a placeholder
Value *Val = getValue(argTy, argValSlot, false);
Constant* C;
if (Val) {
if (!(C = dyn_cast<Constant>(Val))) return failure(true);
BCR_TRACE(5, "Constant Found in ValueTable!\n");
} else { // Nope... find or create a forward ref. for it
C = fwdRefs.GetFwdRefToConstant(argTy, argValSlot);
}
argVec.push_back(C);
}
// Construct a ConstantExpr of the appropriate kind
if (isExprNumArgs == 1) { // All one-operand expressions
V = ConstantExpr::get(opCode, argVec[0], Ty);
} else if (opCode == Instruction::GetElementPtr) { // GetElementPtr
vector<Value*> IdxList(argVec.begin()+1, argVec.end());
V = ConstantExpr::get(opCode, argVec[0], IdxList, Ty);
} else { // All other 2-operand expressions
V = ConstantExpr::get(opCode, argVec[0], argVec[1], Ty);
}
return false;
}
// Ok, not an ConstantExpr. We now know how to read the given type...
switch (Ty->getPrimitiveID()) {
case Type::BoolTyID: {
unsigned Val;
@ -286,38 +334,21 @@ bool BytecodeParser::parseConstantValue(const uchar *&Buf, const uchar *EndBuf,
case 1: { // ConstantPointerRef value...
unsigned Slot;
if (read_vbr(Buf, EndBuf, Slot)) return failure(true);
BCR_TRACE(4, "CPPR: Type: '" << Ty << "' slot: " << Slot << "\n");
BCR_TRACE(4, "CPR: Type: '" << Ty << "' slot: " << Slot << "\n");
// Check to see if we have already read this global variable yet...
Value *Val = getValue(PT, Slot, false);
GlobalValue *GV;
GlobalValue* GV;
if (Val) {
if (!(GV = dyn_cast<GlobalValue>(Val))) return failure(true);
BCR_TRACE(5, "Value Found in ValueTable!\n");
} else { // Nope... see if we have previously forward ref'd it
GlobalRefsType::iterator I = GlobalRefs.find(make_pair(PT, Slot));
if (I != GlobalRefs.end()) {
BCR_TRACE(5, "Previous forward ref found!\n");
GV = I->second;
} else {
BCR_TRACE(5, "Creating new forward ref variable!\n");
// Create a placeholder for the global variable reference...
GlobalVariable *GVar =
new GlobalVariable(PT->getElementType(), false, true);
// Keep track of the fact that we have a forward ref to recycle it
GlobalRefs.insert(make_pair(make_pair(PT, Slot), GVar));
// Must temporarily push this value into the module table...
TheModule->getGlobalList().push_back(GVar);
GV = GVar;
}
if (!(GV = dyn_cast<GlobalValue>(Val))) return failure(true);
BCR_TRACE(5, "Value Found in ValueTable!\n");
} else { // Nope... find or create a forward ref. for it
GV = fwdRefs.GetFwdRefToGlobal(PT, Slot);
}
V = ConstantPointerRef::get(GV);
break;
}
default:
BCR_TRACE(5, "UNKNOWN Pointer Constant Type!\n");
return failure(true);
@ -352,9 +383,12 @@ bool BytecodeParser::ParseConstantPool(const uchar *&Buf, const uchar *EndBuf,
} else {
for (unsigned i = 0; i < NumEntries; ++i) {
Constant *I;
int Slot;
if (parseConstantValue(Buf, EndBuf, Ty, I)) return failure(true);
assert(I && "parseConstantValue returned `!failure' and NULL result");
BCR_TRACE(4, "Read Constant: '" << I << "'\n");
if (insertValue(I, Tab) == -1) return failure(true);
if ((Slot = insertValue(I, Tab)) < 0) return failure(true);
resolveRefsToConstant(I, (unsigned) Slot);
}
}
}

66
lib/Bytecode/Reader/ReaderInternals.h
View File

@ -12,6 +12,8 @@
#include "llvm/BasicBlock.h"
#include "llvm/Instruction.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Constant.h"
#include "Support/NonCopyable.h"
#include <map>
#include <utility>
#include <list>
@ -39,6 +41,36 @@ struct RawInst { // The raw fields out of the bytecode stream...
};
};
class ConstantFwdRefs: public NonCopyable {
Module* TheModule;
// GlobalRefs - This maintains a mapping between <Type, Slot #>'s and forward
// references to global values or constants. Such values may be referenced
// before they are defined, and if so, the temporary object that they
// represent is held here.
//
typedef std::map<std::pair<const Type *, unsigned>,
Value*> GlobalRefsType;
GlobalRefsType GlobalRefs;
Value* find (const Type* Ty, unsigned Slot);
void insert (const Type* Ty, unsigned Slot, Value* V);
void erase (const Type* Ty, unsigned Slot);
public:
// sets the current module pointer: needed to insert placeholder globals
void VisitingModule (Module* M) { TheModule = M; }
// get a forward reference to a global or a constant
GlobalValue* GetFwdRefToGlobal (const PointerType* PT, unsigned Slot);
Constant* GetFwdRefToConstant (const Type* Ty, unsigned Slot);
// resolve all references to the placeholder (if any) for the given value
void ResolveRefsToValue (Value* val, unsigned Slot);
};
class BytecodeParser : public AbstractTypeUser {
std::string Error; // Error message string goes here...
public:
@ -63,14 +95,8 @@ private: // All of this data is transient across calls to ParseBytecode
ValueTable Values, LateResolveValues;
ValueTable ModuleValues, LateResolveModuleValues;
// GlobalRefs - This maintains a mapping between <Type, Slot #>'s and forward
// references to global values. Global values may be referenced before they
// are defined, and if so, the temporary object that they represent is held
// here.
//
typedef std::map<std::pair<const PointerType *, unsigned>,
GlobalVariable*> GlobalRefsType;
GlobalRefsType GlobalRefs;
// fwdRefs - This manages forward references to global values.
ConstantFwdRefs fwdRefs;
// TypesLoaded - This vector mirrors the Values[TypeTyID] plane. It is used
// to deal with forward references to types.
@ -114,11 +140,12 @@ private:
bool getTypeSlot(const Type *Ty, unsigned &Slot);
// DeclareNewGlobalValue - Patch up forward references to global values in the
// form of ConstantPointerRefs.
//
void DeclareNewGlobalValue(GlobalValue *GV, unsigned Slot);
// resolveRefsToGlobal -- resolve forward references to a global
// resolveRefsToConstant -- resolve forward references to a constant
//
void resolveRefsToGlobal(GlobalValue* GV, unsigned Slot);
void resolveRefsToConstant(Constant* C, unsigned Slot);
// refineAbstractType - The callback method is invoked when one of the
// elements of TypeValues becomes more concrete...
//
@ -128,6 +155,7 @@ private:
template<class SuperType>
class PlaceholderDef : public SuperType {
unsigned ID;
PlaceholderDef(); // do not implement
public:
PlaceholderDef(const Type *Ty, unsigned id) : SuperType(Ty), ID(id) {}
unsigned getID() { return ID; }
@ -152,11 +180,23 @@ struct MethPlaceHolderHelper : public Function {
}
};
struct ConstantPlaceHolderHelper : public Constant {
ConstantPlaceHolderHelper(const Type *Ty)
: Constant(Ty) {}
virtual bool isNullValue() const { return false; }
};
typedef PlaceholderDef<InstPlaceHolderHelper> DefPHolder;
typedef PlaceholderDef<BBPlaceHolderHelper> BBPHolder;
typedef PlaceholderDef<MethPlaceHolderHelper> MethPHolder;
typedef PlaceholderDef<ConstantPlaceHolderHelper> ConstPHolder;
static inline unsigned getValueIDNumberFromPlaceHolder(Value *Def) {
if (isa<Constant>(Def))
return ((ConstPHolder*)Def)->getID();
// else discriminate by type
switch (Def->getType()->getPrimitiveID()) {
case Type::LabelTyID: return ((BBPHolder*)Def)->getID();
case Type::FunctionTyID: return ((MethPHolder*)Def)->getID();