Globals.cpp revision 263508 
1//===-- Globals.cpp - Implement the GlobalValue & GlobalVariable class ----===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file implements the GlobalValue & GlobalVariable classes for the IR
11// library.
12//
13//===----------------------------------------------------------------------===//
14
15#include "llvm/IR/GlobalValue.h"
16#include "llvm/ADT/SmallPtrSet.h"
17#include "llvm/IR/Constants.h"
18#include "llvm/IR/DerivedTypes.h"
19#include "llvm/IR/GlobalAlias.h"
20#include "llvm/IR/GlobalVariable.h"
21#include "llvm/IR/Module.h"
22#include "llvm/Support/ErrorHandling.h"
23#include "llvm/Support/LeakDetector.h"
24using namespace llvm;
25
26//===----------------------------------------------------------------------===//
27//                            GlobalValue Class
28//===----------------------------------------------------------------------===//
29
30bool GlobalValue::isMaterializable() const {
31  return getParent() && getParent()->isMaterializable(this);
32}
33bool GlobalValue::isDematerializable() const {
34  return getParent() && getParent()->isDematerializable(this);
35}
36bool GlobalValue::Materialize(std::string *ErrInfo) {
37  return getParent()->Materialize(this, ErrInfo);
38}
39void GlobalValue::Dematerialize() {
40  getParent()->Dematerialize(this);
41}
42
43/// Override destroyConstant to make sure it doesn't get called on
44/// GlobalValue's because they shouldn't be treated like other constants.
45void GlobalValue::destroyConstant() {
46  llvm_unreachable("You can't GV->destroyConstant()!");
47}
48
49/// copyAttributesFrom - copy all additional attributes (those not needed to
50/// create a GlobalValue) from the GlobalValue Src to this one.
51void GlobalValue::copyAttributesFrom(const GlobalValue *Src) {
52  setAlignment(Src->getAlignment());
53  setSection(Src->getSection());
54  setVisibility(Src->getVisibility());
55  setUnnamedAddr(Src->hasUnnamedAddr());
56}
57
58void GlobalValue::setAlignment(unsigned Align) {
59  assert((Align & (Align-1)) == 0 && "Alignment is not a power of 2!");
60  assert(Align <= MaximumAlignment &&
61         "Alignment is greater than MaximumAlignment!");
62  Alignment = Log2_32(Align) + 1;
63  assert(getAlignment() == Align && "Alignment representation error!");
64}
65
66bool GlobalValue::isDeclaration() const {
67  // Globals are definitions if they have an initializer.
68  if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(this))
69    return GV->getNumOperands() == 0;
70
71  // Functions are definitions if they have a body.
72  if (const Function *F = dyn_cast<Function>(this))
73    return F->empty();
74
75  // Aliases are always definitions.
76  assert(isa<GlobalAlias>(this));
77  return false;
78}
79
80//===----------------------------------------------------------------------===//
81// GlobalVariable Implementation
82//===----------------------------------------------------------------------===//
83
84GlobalVariable::GlobalVariable(Type *Ty, bool constant, LinkageTypes Link,
85                               Constant *InitVal,
86                               const Twine &Name, ThreadLocalMode TLMode,
87                               unsigned AddressSpace,
88                               bool isExternallyInitialized)
89  : GlobalValue(PointerType::get(Ty, AddressSpace),
90                Value::GlobalVariableVal,
91                OperandTraits<GlobalVariable>::op_begin(this),
92                InitVal != 0, Link, Name),
93    isConstantGlobal(constant), threadLocalMode(TLMode),
94    isExternallyInitializedConstant(isExternallyInitialized) {
95  if (InitVal) {
96    assert(InitVal->getType() == Ty &&
97           "Initializer should be the same type as the GlobalVariable!");
98    Op<0>() = InitVal;
99  }
100
101  LeakDetector::addGarbageObject(this);
102}
103
104GlobalVariable::GlobalVariable(Module &M, Type *Ty, bool constant,
105                               LinkageTypes Link, Constant *InitVal,
106                               const Twine &Name,
107                               GlobalVariable *Before, ThreadLocalMode TLMode,
108                               unsigned AddressSpace,
109                               bool isExternallyInitialized)
110  : GlobalValue(PointerType::get(Ty, AddressSpace),
111                Value::GlobalVariableVal,
112                OperandTraits<GlobalVariable>::op_begin(this),
113                InitVal != 0, Link, Name),
114    isConstantGlobal(constant), threadLocalMode(TLMode),
115    isExternallyInitializedConstant(isExternallyInitialized) {
116  if (InitVal) {
117    assert(InitVal->getType() == Ty &&
118           "Initializer should be the same type as the GlobalVariable!");
119    Op<0>() = InitVal;
120  }
121
122  LeakDetector::addGarbageObject(this);
123
124  if (Before)
125    Before->getParent()->getGlobalList().insert(Before, this);
126  else
127    M.getGlobalList().push_back(this);
128}
129
130void GlobalVariable::setParent(Module *parent) {
131  if (getParent())
132    LeakDetector::addGarbageObject(this);
133  Parent = parent;
134  if (getParent())
135    LeakDetector::removeGarbageObject(this);
136}
137
138void GlobalVariable::removeFromParent() {
139  getParent()->getGlobalList().remove(this);
140}
141
142void GlobalVariable::eraseFromParent() {
143  getParent()->getGlobalList().erase(this);
144}
145
146void GlobalVariable::replaceUsesOfWithOnConstant(Value *From, Value *To,
147                                                 Use *U) {
148  // If you call this, then you better know this GVar has a constant
149  // initializer worth replacing. Enforce that here.
150  assert(getNumOperands() == 1 &&
151         "Attempt to replace uses of Constants on a GVar with no initializer");
152
153  // And, since you know it has an initializer, the From value better be
154  // the initializer :)
155  assert(getOperand(0) == From &&
156         "Attempt to replace wrong constant initializer in GVar");
157
158  // And, you better have a constant for the replacement value
159  assert(isa<Constant>(To) &&
160         "Attempt to replace GVar initializer with non-constant");
161
162  // Okay, preconditions out of the way, replace the constant initializer.
163  this->setOperand(0, cast<Constant>(To));
164}
165
166void GlobalVariable::setInitializer(Constant *InitVal) {
167  if (InitVal == 0) {
168    if (hasInitializer()) {
169      Op<0>().set(0);
170      NumOperands = 0;
171    }
172  } else {
173    assert(InitVal->getType() == getType()->getElementType() &&
174           "Initializer type must match GlobalVariable type");
175    if (!hasInitializer())
176      NumOperands = 1;
177    Op<0>().set(InitVal);
178  }
179}
180
181/// copyAttributesFrom - copy all additional attributes (those not needed to
182/// create a GlobalVariable) from the GlobalVariable Src to this one.
183void GlobalVariable::copyAttributesFrom(const GlobalValue *Src) {
184  assert(isa<GlobalVariable>(Src) && "Expected a GlobalVariable!");
185  GlobalValue::copyAttributesFrom(Src);
186  const GlobalVariable *SrcVar = cast<GlobalVariable>(Src);
187  setThreadLocal(SrcVar->isThreadLocal());
188}
189
190
191//===----------------------------------------------------------------------===//
192// GlobalAlias Implementation
193//===----------------------------------------------------------------------===//
194
195GlobalAlias::GlobalAlias(Type *Ty, LinkageTypes Link,
196                         const Twine &Name, Constant* aliasee,
197                         Module *ParentModule)
198  : GlobalValue(Ty, Value::GlobalAliasVal, &Op<0>(), 1, Link, Name) {
199  LeakDetector::addGarbageObject(this);
200
201  if (aliasee)
202    assert(aliasee->getType() == Ty && "Alias and aliasee types should match!");
203  Op<0>() = aliasee;
204
205  if (ParentModule)
206    ParentModule->getAliasList().push_back(this);
207}
208
209void GlobalAlias::setParent(Module *parent) {
210  if (getParent())
211    LeakDetector::addGarbageObject(this);
212  Parent = parent;
213  if (getParent())
214    LeakDetector::removeGarbageObject(this);
215}
216
217void GlobalAlias::removeFromParent() {
218  getParent()->getAliasList().remove(this);
219}
220
221void GlobalAlias::eraseFromParent() {
222  getParent()->getAliasList().erase(this);
223}
224
225void GlobalAlias::setAliasee(Constant *Aliasee) {
226  assert((!Aliasee || Aliasee->getType() == getType()) &&
227         "Alias and aliasee types should match!");
228
229  setOperand(0, Aliasee);
230}
231
232GlobalValue *GlobalAlias::getAliasedGlobal() {
233  Constant *C = getAliasee();
234  if (C == 0) return 0;
235
236  if (GlobalValue *GV = dyn_cast<GlobalValue>(C))
237    return GV;
238
239  ConstantExpr *CE = cast<ConstantExpr>(C);
240  assert((CE->getOpcode() == Instruction::BitCast ||
241          CE->getOpcode() == Instruction::GetElementPtr) &&
242         "Unsupported aliasee");
243
244  return cast<GlobalValue>(CE->getOperand(0));
245}
246
247GlobalValue *GlobalAlias::resolveAliasedGlobal(bool stopOnWeak) {
248  SmallPtrSet<GlobalValue*, 3> Visited;
249
250  // Check if we need to stop early.
251  if (stopOnWeak && mayBeOverridden())
252    return this;
253
254  GlobalValue *GV = getAliasedGlobal();
255  Visited.insert(GV);
256
257  // Iterate over aliasing chain, stopping on weak alias if necessary.
258  while (GlobalAlias *GA = dyn_cast<GlobalAlias>(GV)) {
259    if (stopOnWeak && GA->mayBeOverridden())
260      break;
261
262    GV = GA->getAliasedGlobal();
263
264    if (!Visited.insert(GV))
265      return 0;
266  }
267
268  return GV;
269}
270