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//===-- Globals.cpp - Implement the Global object classes -----------------===//
//
// 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 file implements the GlobalValue & GlobalVariable classes for the VMCore
// library.
//
//===----------------------------------------------------------------------===//
#include "llvm/DerivedTypes.h"
#include "llvm/GlobalVariable.h"
#include "llvm/Module.h"
#include "llvm/SymbolTable.h"
#include "Support/LeakDetector.h"
using namespace llvm;
//===----------------------------------------------------------------------===//
// GlobalValue Class
//===----------------------------------------------------------------------===//
/// This could be named "SafeToDestroyGlobalValue". It just makes sure that
/// there are no non-constant uses of this GlobalValue. If there aren't then
/// this and the transitive closure of the constants can be deleted. See the
/// destructor for details.
static bool removeDeadConstantUsers(Constant* C) {
if (isa<GlobalValue>(C)) return false; // Cannot remove this
while (!C->use_empty())
if (Constant *User = dyn_cast<Constant>(C->use_back())) {
if (!removeDeadConstantUsers(User))
return false; // Constant wasn't dead
} else {
return false; // Non-constant usage;
}
C->destroyConstant();
return true;
}
/// removeDeadConstantUsers - If there are any dead constant users dangling
/// off of this global value, remove them. This method is useful for clients
/// that want to check to see if a global is unused, but don't want to deal
/// with potentially dead constants hanging off of the globals.
///
/// This function returns true if the global value is now dead. If all
/// users of this global are not dead, this method may return false and
/// leave some of them around.
void GlobalValue::removeDeadConstantUsers() {
while(!use_empty()) {
if (Constant* User = dyn_cast<Constant>(use_back())) {
if (!::removeDeadConstantUsers(User))
return; // Constant wasn't dead
} else {
return; // Non-constant usage;
}
}
}
/// Override destroyConstant to make sure it doesn't get called on
/// GlobalValue's because they shouldn't be treated like other constants.
void GlobalValue::destroyConstant() {
assert(0 && "You can't GV->destroyConstant()!");
abort();
}
//===----------------------------------------------------------------------===//
// GlobalVariable Implementation
//===----------------------------------------------------------------------===//
GlobalVariable::GlobalVariable(const Type *Ty, bool constant, LinkageTypes Link,
Constant *Initializer,
const std::string &Name, Module *ParentModule)
: GlobalValue(PointerType::get(Ty), Value::GlobalVariableVal, Link, Name),
isConstantGlobal(constant) {
if (Initializer) Operands.push_back(Use((Value*)Initializer, this));
LeakDetector::addGarbageObject(this);
if (ParentModule)
ParentModule->getGlobalList().push_back(this);
}
void GlobalVariable::setParent(Module *parent) {
if (getParent())
LeakDetector::addGarbageObject(this);
Parent = parent;
if (getParent())
LeakDetector::removeGarbageObject(this);
}
// Specialize setName to take care of symbol table majik
void GlobalVariable::setName(const std::string &name, SymbolTable *ST) {
Module *P;
assert((ST == 0 || (!getParent() || ST == &getParent()->getSymbolTable())) &&
"Invalid symtab argument!");
if ((P = getParent()) && hasName()) P->getSymbolTable().remove(this);
Value::setName(name);
if (P && hasName()) P->getSymbolTable().insert(this);
}
void GlobalVariable::replaceUsesOfWithOnConstant(Value *From, Value *To,
bool DisableChecking )
{
// If you call this, then you better know this GVar has a constant
// initializer worth replacing. Enforce that here.
assert(getNumOperands() == 1 &&
"Attempt to replace uses of Constants on a GVar with no initializer");
// And, since you know it has an initializer, the From value better be
// the initializer :)
assert(getOperand(0) == From &&
"Attempt to replace wrong constant initializer in GVar");
// And, you better have a constant for the replacement value
assert(isa<Constant>(To) &&
"Attempt to replace GVar initializer with non-constant");
// Okay, preconditions out of the way, replace the constant initializer.
this->setOperand(0, cast<Constant>(To));
}
// vim: sw=2 ai
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