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/Constants.h"
17#include "llvm/Function.h"
18#include "llvm/InlineAsm.h"
19#include "llvm/Instructions.h"
20#include "llvm/Metadata.h"
21using namespace llvm;
22
23// Out of line method to get vtable etc for class.
24void ValueMapTypeRemapper::Anchor() {}
25
26Value *llvm::MapValue(const Value *V, ValueToValueMapTy &VM, RemapFlags Flags,
27                      ValueMapTypeRemapper *TypeMapper) {
28  ValueToValueMapTy::iterator I = VM.find(V);
29
30  // If the value already exists in the map, use it.
31  if (I != VM.end() && I->second) return I->second;
32
33  // Global values do not need to be seeded into the VM if they
34  // are using the identity mapping.
35  if (isa<GlobalValue>(V) || isa<MDString>(V))
36    return VM[V] = const_cast<Value*>(V);
37
38  if (const InlineAsm *IA = dyn_cast<InlineAsm>(V)) {
39    // Inline asm may need *type* remapping.
40    FunctionType *NewTy = IA->getFunctionType();
41    if (TypeMapper) {
42      NewTy = cast<FunctionType>(TypeMapper->remapType(NewTy));
43
44      if (NewTy != IA->getFunctionType())
45        V = InlineAsm::get(NewTy, IA->getAsmString(), IA->getConstraintString(),
46                           IA->hasSideEffects(), IA->isAlignStack());
47    }
48
49    return VM[V] = const_cast<Value*>(V);
50  }
51
52
53  if (const MDNode *MD = dyn_cast<MDNode>(V)) {
54    // If this is a module-level metadata and we know that nothing at the module
55    // level is changing, then use an identity mapping.
56    if (!MD->isFunctionLocal() && (Flags & RF_NoModuleLevelChanges))
57      return VM[V] = const_cast<Value*>(V);
58
59    // Create a dummy node in case we have a metadata cycle.
60    MDNode *Dummy = MDNode::getTemporary(V->getContext(), ArrayRef<Value*>());
61    VM[V] = Dummy;
62
63    // Check all operands to see if any need to be remapped.
64    for (unsigned i = 0, e = MD->getNumOperands(); i != e; ++i) {
65      Value *OP = MD->getOperand(i);
66      if (OP == 0 || MapValue(OP, VM, Flags, TypeMapper) == OP) continue;
67
68      // Ok, at least one operand needs remapping.
69      SmallVector<Value*, 4> Elts;
70      Elts.reserve(MD->getNumOperands());
71      for (i = 0; i != e; ++i) {
72        Value *Op = MD->getOperand(i);
73        Elts.push_back(Op ? MapValue(Op, VM, Flags, TypeMapper) : 0);
74      }
75      MDNode *NewMD = MDNode::get(V->getContext(), Elts);
76      Dummy->replaceAllUsesWith(NewMD);
77      VM[V] = NewMD;
78      MDNode::deleteTemporary(Dummy);
79      return NewMD;
80    }
81
82    VM[V] = const_cast<Value*>(V);
83    MDNode::deleteTemporary(Dummy);
84
85    // No operands needed remapping.  Use an identity mapping.
86    return const_cast<Value*>(V);
87  }
88
89  // Okay, this either must be a constant (which may or may not be mappable) or
90  // is something that is not in the mapping table.
91  Constant *C = const_cast<Constant*>(dyn_cast<Constant>(V));
92  if (C == 0)
93    return 0;
94
95  if (BlockAddress *BA = dyn_cast<BlockAddress>(C)) {
96    Function *F =
97      cast<Function>(MapValue(BA->getFunction(), VM, Flags, TypeMapper));
98    BasicBlock *BB = cast_or_null<BasicBlock>(MapValue(BA->getBasicBlock(), VM,
99                                                       Flags, TypeMapper));
100    return VM[V] = BlockAddress::get(F, BB ? BB : BA->getBasicBlock());
101  }
102
103  // Otherwise, we have some other constant to remap.  Start by checking to see
104  // if all operands have an identity remapping.
105  unsigned OpNo = 0, NumOperands = C->getNumOperands();
106  Value *Mapped = 0;
107  for (; OpNo != NumOperands; ++OpNo) {
108    Value *Op = C->getOperand(OpNo);
109    Mapped = MapValue(Op, VM, Flags, TypeMapper);
110    if (Mapped != C) break;
111  }
112
113  // See if the type mapper wants to remap the type as well.
114  Type *NewTy = C->getType();
115  if (TypeMapper)
116    NewTy = TypeMapper->remapType(NewTy);
117
118  // If the result type and all operands match up, then just insert an identity
119  // mapping.
120  if (OpNo == NumOperands && NewTy == C->getType())
121    return VM[V] = C;
122
123  // Okay, we need to create a new constant.  We've already processed some or
124  // all of the operands, set them all up now.
125  SmallVector<Constant*, 8> Ops;
126  Ops.reserve(NumOperands);
127  for (unsigned j = 0; j != OpNo; ++j)
128    Ops.push_back(cast<Constant>(C->getOperand(j)));
129
130  // If one of the operands mismatch, push it and the other mapped operands.
131  if (OpNo != NumOperands) {
132    Ops.push_back(cast<Constant>(Mapped));
133
134    // Map the rest of the operands that aren't processed yet.
135    for (++OpNo; OpNo != NumOperands; ++OpNo)
136      Ops.push_back(MapValue(cast<Constant>(C->getOperand(OpNo)), VM,
137                             Flags, TypeMapper));
138  }
139
140  if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C))
141    return VM[V] = CE->getWithOperands(Ops, NewTy);
142  if (isa<ConstantArray>(C))
143    return VM[V] = ConstantArray::get(cast<ArrayType>(NewTy), Ops);
144  if (isa<ConstantStruct>(C))
145    return VM[V] = ConstantStruct::get(cast<StructType>(NewTy), Ops);
146  if (isa<ConstantVector>(C))
147    return VM[V] = ConstantVector::get(Ops);
148  // If this is a no-operand constant, it must be because the type was remapped.
149  if (isa<UndefValue>(C))
150    return VM[V] = UndefValue::get(NewTy);
151  if (isa<ConstantAggregateZero>(C))
152    return VM[V] = ConstantAggregateZero::get(NewTy);
153  assert(isa<ConstantPointerNull>(C));
154  return VM[V] = ConstantPointerNull::get(cast<PointerType>(NewTy));
155}
156
157/// RemapInstruction - Convert the instruction operands from referencing the
158/// current values into those specified by VMap.
159///
160void llvm::RemapInstruction(Instruction *I, ValueToValueMapTy &VMap,
161                            RemapFlags Flags, ValueMapTypeRemapper *TypeMapper){
162  // Remap operands.
163  for (User::op_iterator op = I->op_begin(), E = I->op_end(); op != E; ++op) {
164    Value *V = MapValue(*op, VMap, Flags, TypeMapper);
165    // If we aren't ignoring missing entries, assert that something happened.
166    if (V != 0)
167      *op = V;
168    else
169      assert((Flags & RF_IgnoreMissingEntries) &&
170             "Referenced value not in value map!");
171  }
172
173  // Remap phi nodes' incoming blocks.
174  if (PHINode *PN = dyn_cast<PHINode>(I)) {
175    for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
176      Value *V = MapValue(PN->getIncomingBlock(i), VMap, Flags);
177      // If we aren't ignoring missing entries, assert that something happened.
178      if (V != 0)
179        PN->setIncomingBlock(i, cast<BasicBlock>(V));
180      else
181        assert((Flags & RF_IgnoreMissingEntries) &&
182               "Referenced block not in value map!");
183    }
184  }
185
186  // Remap attached metadata.
187  SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
188  I->getAllMetadata(MDs);
189  for (SmallVectorImpl<std::pair<unsigned, MDNode *> >::iterator
190       MI = MDs.begin(), ME = MDs.end(); MI != ME; ++MI) {
191    MDNode *Old = MI->second;
192    MDNode *New = MapValue(Old, VMap, Flags, TypeMapper);
193    if (New != Old)
194      I->setMetadata(MI->first, New);
195  }
196
197  // If the instruction's type is being remapped, do so now.
198  if (TypeMapper)
199    I->mutateType(TypeMapper->remapType(I->getType()));
200}
201