ValueMapper.cpp revision 1fd7096407d5e598ed3366a1141548e71273f1c5 
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/BasicBlock.h"
17#include "llvm/DerivedTypes.h"  // For getNullValue(Type::Int32Ty)
18#include "llvm/Constants.h"
19#include "llvm/GlobalValue.h"
20#include "llvm/Instruction.h"
21#include "llvm/LLVMContext.h"
22#include "llvm/MDNode.h"
23#include "llvm/ADT/SmallVector.h"
24#include "llvm/Support/ErrorHandling.h"
25using namespace llvm;
26
27Value *llvm::MapValue(const Value *V, ValueMapTy &VM, LLVMContext &Context) {
28  Value *&VMSlot = VM[V];
29  if (VMSlot) return VMSlot;      // Does it exist in the map yet?
30
31  // NOTE: VMSlot can be invalidated by any reference to VM, which can grow the
32  // DenseMap.  This includes any recursive calls to MapValue.
33
34  // Global values and metadata do not need to be seeded into the ValueMap if
35  // they are using the identity mapping.
36  if (isa<GlobalValue>(V) || isa<InlineAsm>(V) || isa<MetadataBase>(V))
37    return VMSlot = const_cast<Value*>(V);
38
39  if (Constant *C = const_cast<Constant*>(dyn_cast<Constant>(V))) {
40    if (isa<ConstantInt>(C) || isa<ConstantFP>(C) ||
41        isa<ConstantPointerNull>(C) || isa<ConstantAggregateZero>(C) ||
42        isa<UndefValue>(C) || isa<MDString>(C))
43      return VMSlot = C;           // Primitive constants map directly
44    else if (ConstantArray *CA = dyn_cast<ConstantArray>(C)) {
45      for (User::op_iterator b = CA->op_begin(), i = b, e = CA->op_end();
46           i != e; ++i) {
47        Value *MV = MapValue(*i, VM, Context);
48        if (MV != *i) {
49          // This array must contain a reference to a global, make a new array
50          // and return it.
51          //
52          std::vector<Constant*> Values;
53          Values.reserve(CA->getNumOperands());
54          for (User::op_iterator j = b; j != i; ++j)
55            Values.push_back(cast<Constant>(*j));
56          Values.push_back(cast<Constant>(MV));
57          for (++i; i != e; ++i)
58            Values.push_back(cast<Constant>(MapValue(*i, VM, Context)));
59          return VM[V] = ConstantArray::get(CA->getType(), Values);
60        }
61      }
62      return VM[V] = C;
63
64    } else if (ConstantStruct *CS = dyn_cast<ConstantStruct>(C)) {
65      for (User::op_iterator b = CS->op_begin(), i = b, e = CS->op_end();
66           i != e; ++i) {
67        Value *MV = MapValue(*i, VM, Context);
68        if (MV != *i) {
69          // This struct must contain a reference to a global, make a new struct
70          // and return it.
71          //
72          std::vector<Constant*> Values;
73          Values.reserve(CS->getNumOperands());
74          for (User::op_iterator j = b; j != i; ++j)
75            Values.push_back(cast<Constant>(*j));
76          Values.push_back(cast<Constant>(MV));
77          for (++i; i != e; ++i)
78            Values.push_back(cast<Constant>(MapValue(*i, VM, Context)));
79          return VM[V] = ConstantStruct::get(CS->getType(), Values);
80        }
81      }
82      return VM[V] = C;
83
84    } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
85      std::vector<Constant*> Ops;
86      for (User::op_iterator i = CE->op_begin(), e = CE->op_end(); i != e; ++i)
87        Ops.push_back(cast<Constant>(MapValue(*i, VM, Context)));
88      return VM[V] = CE->getWithOperands(Ops);
89    } else if (ConstantVector *CP = dyn_cast<ConstantVector>(C)) {
90      for (User::op_iterator b = CP->op_begin(), i = b, e = CP->op_end();
91           i != e; ++i) {
92        Value *MV = MapValue(*i, VM, Context);
93        if (MV != *i) {
94          // This vector value must contain a reference to a global, make a new
95          // vector constant and return it.
96          //
97          std::vector<Constant*> Values;
98          Values.reserve(CP->getNumOperands());
99          for (User::op_iterator j = b; j != i; ++j)
100            Values.push_back(cast<Constant>(*j));
101          Values.push_back(cast<Constant>(MV));
102          for (++i; i != e; ++i)
103            Values.push_back(cast<Constant>(MapValue(*i, VM, Context)));
104          return VM[V] = Context.getConstantVector(Values);
105        }
106      }
107      return VM[V] = C;
108
109    } else {
110      llvm_unreachable("Unknown type of constant!");
111    }
112  }
113  return 0;
114}
115
116/// RemapInstruction - Convert the instruction operands from referencing the
117/// current values into those specified by ValueMap.
118///
119void llvm::RemapInstruction(Instruction *I, ValueMapTy &ValueMap) {
120  for (User::op_iterator op = I->op_begin(), E = I->op_end(); op != E; ++op) {
121    Value *V = MapValue(*op, ValueMap, I->getParent()->getContext());
122    assert(V && "Referenced value not in value map!");
123    *op = V;
124  }
125}
126