ValueMapper.cpp revision dce4a407a24b04eebc6a376f8e62b41aaa7b071f 
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"
21using namespace llvm;
22
23// Out of line method to get vtable etc for class.
24void ValueMapTypeRemapper::anchor() {}
25void ValueMaterializer::anchor() {}
26
27Value *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///
183void 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