//===-- 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 "llvm/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 *InitVal, const std::string &Name, Module *ParentModule) : GlobalValue(PointerType::get(Ty), Value::GlobalVariableVal, &Initializer, InitVal != 0, Link, Name), isConstantGlobal(constant) { if (InitVal) { assert(InitVal->getType() == Ty && "Initializer should be the same type as the GlobalVariable!"); Initializer.init(InitVal, this); } else { Initializer.init(0, 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); } void GlobalVariable::removeFromParent() { getParent()->getGlobalList().remove(this); } void GlobalVariable::eraseFromParent() { getParent()->getGlobalList().erase(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