1 //===- ValueMapper.cpp - Interface shared by lib/Transforms/Utils ---------===//
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 defines the MapValue function, which is shared by various parts of
11 // the lib/Transforms/Utils library.
12 //
13 //===----------------------------------------------------------------------===//
14
15 #include "llvm/Transforms/Utils/ValueMapper.h"
16 #include "llvm/IR/Constants.h"
17 #include "llvm/IR/Function.h"
18 #include "llvm/IR/InlineAsm.h"
19 #include "llvm/IR/Instructions.h"
20 #include "llvm/IR/Metadata.h"
21 using namespace llvm;
22
23 // Out of line method to get vtable etc for class.
anchor()24 void ValueMapTypeRemapper::anchor() {}
anchor()25 void ValueMaterializer::anchor() {}
26
MapValue(const Value * V,ValueToValueMapTy & VM,RemapFlags Flags,ValueMapTypeRemapper * TypeMapper,ValueMaterializer * Materializer)27 Value *llvm::MapValue(const Value *V, ValueToValueMapTy &VM, RemapFlags Flags,
28 ValueMapTypeRemapper *TypeMapper,
29 ValueMaterializer *Materializer) {
30 ValueToValueMapTy::iterator I = VM.find(V);
31
32 // If the value already exists in the map, use it.
33 if (I != VM.end() && I->second) return I->second;
34
35 // If we have a materializer and it can materialize a value, use that.
36 if (Materializer) {
37 if (Value *NewV = Materializer->materializeValueFor(const_cast<Value*>(V)))
38 return VM[V] = NewV;
39 }
40
41 // Global values do not need to be seeded into the VM if they
42 // are using the identity mapping.
43 if (isa<GlobalValue>(V) || isa<MDString>(V))
44 return VM[V] = const_cast<Value*>(V);
45
46 if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
47 // Inline asm may need *type* remapping.
48 FunctionType *NewTy = IA->getFunctionType();
49 if (TypeMapper) {
50 NewTy = cast<FunctionType>(TypeMapper->remapType(NewTy));
51
52 if (NewTy != IA->getFunctionType())
53 V = InlineAsm::get(NewTy, IA->getAsmString(), IA->getConstraintString(),
54 IA->hasSideEffects(), IA->isAlignStack());
55 }
56
57 return VM[V] = const_cast<Value*>(V);
58 }
59
60
61 if (const MDNode *MD = dyn_cast<MDNode>(V)) {
62 // If this is a module-level metadata and we know that nothing at the module
63 // level is changing, then use an identity mapping.
64 if (!MD->isFunctionLocal() && (Flags & RF_NoModuleLevelChanges))
65 return VM[V] = const_cast<Value*>(V);
66
67 // Create a dummy node in case we have a metadata cycle.
68 MDNode *Dummy = MDNode::getTemporary(V->getContext(), None);
69 VM[V] = Dummy;
70
71 // Check all operands to see if any need to be remapped.
72 for (unsigned i = 0, e = MD->getNumOperands(); i != e; ++i) {
73 Value *OP = MD->getOperand(i);
74 if (!OP) continue;
75 Value *Mapped_OP = MapValue(OP, VM, Flags, TypeMapper, Materializer);
76 // Use identity map if Mapped_Op is null and we can ignore missing
77 // entries.
78 if (Mapped_OP == OP ||
79 (Mapped_OP == nullptr && (Flags & RF_IgnoreMissingEntries)))
80 continue;
81
82 // Ok, at least one operand needs remapping.
83 SmallVector<Value*, 4> Elts;
84 Elts.reserve(MD->getNumOperands());
85 for (i = 0; i != e; ++i) {
86 Value *Op = MD->getOperand(i);
87 if (!Op)
88 Elts.push_back(nullptr);
89 else {
90 Value *Mapped_Op = MapValue(Op, VM, Flags, TypeMapper, Materializer);
91 // Use identity map if Mapped_Op is null and we can ignore missing
92 // entries.
93 if (Mapped_Op == nullptr && (Flags & RF_IgnoreMissingEntries))
94 Mapped_Op = Op;
95 Elts.push_back(Mapped_Op);
96 }
97 }
98 MDNode *NewMD = MDNode::get(V->getContext(), Elts);
99 Dummy->replaceAllUsesWith(NewMD);
100 VM[V] = NewMD;
101 MDNode::deleteTemporary(Dummy);
102 return NewMD;
103 }
104
105 VM[V] = const_cast<Value*>(V);
106 MDNode::deleteTemporary(Dummy);
107
108 // No operands needed remapping. Use an identity mapping.
109 return const_cast<Value*>(V);
110 }
111
112 // Okay, this either must be a constant (which may or may not be mappable) or
113 // is something that is not in the mapping table.
114 Constant *C = const_cast<Constant*>(dyn_cast<Constant>(V));
115 if (!C)
116 return nullptr;
117
118 if (BlockAddress *BA = dyn_cast<BlockAddress>(C)) {
119 Function *F =
120 cast<Function>(MapValue(BA->getFunction(), VM, Flags, TypeMapper, Materializer));
121 BasicBlock *BB = cast_or_null<BasicBlock>(MapValue(BA->getBasicBlock(), VM,
122 Flags, TypeMapper, Materializer));
123 return VM[V] = BlockAddress::get(F, BB ? BB : BA->getBasicBlock());
124 }
125
126 // Otherwise, we have some other constant to remap. Start by checking to see
127 // if all operands have an identity remapping.
128 unsigned OpNo = 0, NumOperands = C->getNumOperands();
129 Value *Mapped = nullptr;
130 for (; OpNo != NumOperands; ++OpNo) {
131 Value *Op = C->getOperand(OpNo);
132 Mapped = MapValue(Op, VM, Flags, TypeMapper, Materializer);
133 if (Mapped != C) break;
134 }
135
136 // See if the type mapper wants to remap the type as well.
137 Type *NewTy = C->getType();
138 if (TypeMapper)
139 NewTy = TypeMapper->remapType(NewTy);
140
141 // If the result type and all operands match up, then just insert an identity
142 // mapping.
143 if (OpNo == NumOperands && NewTy == C->getType())
144 return VM[V] = C;
145
146 // Okay, we need to create a new constant. We've already processed some or
147 // all of the operands, set them all up now.
148 SmallVector<Constant*, 8> Ops;
149 Ops.reserve(NumOperands);
150 for (unsigned j = 0; j != OpNo; ++j)
151 Ops.push_back(cast<Constant>(C->getOperand(j)));
152
153 // If one of the operands mismatch, push it and the other mapped operands.
154 if (OpNo != NumOperands) {
155 Ops.push_back(cast<Constant>(Mapped));
156
157 // Map the rest of the operands that aren't processed yet.
158 for (++OpNo; OpNo != NumOperands; ++OpNo)
159 Ops.push_back(MapValue(cast<Constant>(C->getOperand(OpNo)), VM,
160 Flags, TypeMapper, Materializer));
161 }
162
163 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C))
164 return VM[V] = CE->getWithOperands(Ops, NewTy);
165 if (isa<ConstantArray>(C))
166 return VM[V] = ConstantArray::get(cast<ArrayType>(NewTy), Ops);
167 if (isa<ConstantStruct>(C))
168 return VM[V] = ConstantStruct::get(cast<StructType>(NewTy), Ops);
169 if (isa<ConstantVector>(C))
170 return VM[V] = ConstantVector::get(Ops);
171 // If this is a no-operand constant, it must be because the type was remapped.
172 if (isa<UndefValue>(C))
173 return VM[V] = UndefValue::get(NewTy);
174 if (isa<ConstantAggregateZero>(C))
175 return VM[V] = ConstantAggregateZero::get(NewTy);
176 assert(isa<ConstantPointerNull>(C));
177 return VM[V] = ConstantPointerNull::get(cast<PointerType>(NewTy));
178 }
179
180 /// RemapInstruction - Convert the instruction operands from referencing the
181 /// current values into those specified by VMap.
182 ///
RemapInstruction(Instruction * I,ValueToValueMapTy & VMap,RemapFlags Flags,ValueMapTypeRemapper * TypeMapper,ValueMaterializer * Materializer)183 void llvm::RemapInstruction(Instruction *I, ValueToValueMapTy &VMap,
184 RemapFlags Flags, ValueMapTypeRemapper *TypeMapper,
185 ValueMaterializer *Materializer){
186 // Remap operands.
187 for (User::op_iterator op = I->op_begin(), E = I->op_end(); op != E; ++op) {
188 Value *V = MapValue(*op, VMap, Flags, TypeMapper, Materializer);
189 // If we aren't ignoring missing entries, assert that something happened.
190 if (V)
191 *op = V;
192 else
193 assert((Flags & RF_IgnoreMissingEntries) &&
194 "Referenced value not in value map!");
195 }
196
197 // Remap phi nodes' incoming blocks.
198 if (PHINode *PN = dyn_cast<PHINode>(I)) {
199 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
200 Value *V = MapValue(PN->getIncomingBlock(i), VMap, Flags);
201 // If we aren't ignoring missing entries, assert that something happened.
202 if (V)
203 PN->setIncomingBlock(i, cast<BasicBlock>(V));
204 else
205 assert((Flags & RF_IgnoreMissingEntries) &&
206 "Referenced block not in value map!");
207 }
208 }
209
210 // Remap attached metadata.
211 SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
212 I->getAllMetadata(MDs);
213 for (SmallVectorImpl<std::pair<unsigned, MDNode *> >::iterator
214 MI = MDs.begin(), ME = MDs.end(); MI != ME; ++MI) {
215 MDNode *Old = MI->second;
216 MDNode *New = MapValue(Old, VMap, Flags, TypeMapper, Materializer);
217 if (New != Old)
218 I->setMetadata(MI->first, New);
219 }
220
221 // If the instruction's type is being remapped, do so now.
222 if (TypeMapper)
223 I->mutateType(TypeMapper->remapType(I->getType()));
224 }
225