forked from OSchip/llvm-project
132 lines
4.6 KiB
C++
132 lines
4.6 KiB
C++
//===-- Globals.cpp - Implement the Global object classes -----------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file was developed by the LLVM research group and is distributed under
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// the University of Illinois Open Source License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the GlobalValue & GlobalVariable classes for the VMCore
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// library.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/DerivedTypes.h"
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#include "llvm/GlobalVariable.h"
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#include "llvm/Module.h"
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#include "llvm/SymbolTable.h"
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#include "llvm/Support/LeakDetector.h"
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using namespace llvm;
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//===----------------------------------------------------------------------===//
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// GlobalValue Class
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//===----------------------------------------------------------------------===//
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/// This could be named "SafeToDestroyGlobalValue". It just makes sure that
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/// there are no non-constant uses of this GlobalValue. If there aren't then
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/// this and the transitive closure of the constants can be deleted. See the
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/// destructor for details.
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static bool removeDeadConstantUsers(Constant* C) {
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if (isa<GlobalValue>(C)) return false; // Cannot remove this
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while (!C->use_empty())
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if (Constant *User = dyn_cast<Constant>(C->use_back())) {
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if (!removeDeadConstantUsers(User))
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return false; // Constant wasn't dead
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} else {
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return false; // Non-constant usage;
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}
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C->destroyConstant();
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return true;
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}
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/// removeDeadConstantUsers - If there are any dead constant users dangling
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/// off of this global value, remove them. This method is useful for clients
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/// that want to check to see if a global is unused, but don't want to deal
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/// with potentially dead constants hanging off of the globals.
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///
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/// This function returns true if the global value is now dead. If all
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/// users of this global are not dead, this method may return false and
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/// leave some of them around.
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void GlobalValue::removeDeadConstantUsers() {
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while(!use_empty()) {
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if (Constant* User = dyn_cast<Constant>(use_back())) {
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if (!::removeDeadConstantUsers(User))
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return; // Constant wasn't dead
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} else {
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return; // Non-constant usage;
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}
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}
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}
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/// Override destroyConstant to make sure it doesn't get called on
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/// GlobalValue's because they shouldn't be treated like other constants.
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void GlobalValue::destroyConstant() {
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assert(0 && "You can't GV->destroyConstant()!");
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abort();
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}
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//===----------------------------------------------------------------------===//
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// GlobalVariable Implementation
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//===----------------------------------------------------------------------===//
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GlobalVariable::GlobalVariable(const Type *Ty, bool constant, LinkageTypes Link,
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Constant *InitVal,
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const std::string &Name, Module *ParentModule)
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: GlobalValue(PointerType::get(Ty), Value::GlobalVariableVal,
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&Initializer, InitVal != 0, Link, Name),
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isConstantGlobal(constant) {
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if (InitVal) {
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assert(InitVal->getType() == Ty &&
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"Initializer should be the same type as the GlobalVariable!");
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Initializer.init(InitVal, this);
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} else {
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Initializer.init(0, this);
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}
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LeakDetector::addGarbageObject(this);
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if (ParentModule)
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ParentModule->getGlobalList().push_back(this);
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}
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void GlobalVariable::setParent(Module *parent) {
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if (getParent())
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LeakDetector::addGarbageObject(this);
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Parent = parent;
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if (getParent())
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LeakDetector::removeGarbageObject(this);
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}
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void GlobalVariable::removeFromParent() {
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getParent()->getGlobalList().remove(this);
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}
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void GlobalVariable::eraseFromParent() {
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getParent()->getGlobalList().erase(this);
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}
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void GlobalVariable::replaceUsesOfWithOnConstant(Value *From, Value *To,
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bool DisableChecking) {
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// If you call this, then you better know this GVar has a constant
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// initializer worth replacing. Enforce that here.
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assert(getNumOperands() == 1 &&
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"Attempt to replace uses of Constants on a GVar with no initializer");
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// And, since you know it has an initializer, the From value better be
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// the initializer :)
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assert(getOperand(0) == From &&
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"Attempt to replace wrong constant initializer in GVar");
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// And, you better have a constant for the replacement value
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assert(isa<Constant>(To) &&
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"Attempt to replace GVar initializer with non-constant");
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// Okay, preconditions out of the way, replace the constant initializer.
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this->setOperand(0, cast<Constant>(To));
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}
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// vim: sw=2 ai
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