ValueMapper.cpp revision 589423cd634b0836c0f2ec4c8dbe28b8807916f1 
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/DerivedTypes.h"  // For getNullValue(Type::Int32Ty)
17#include "llvm/Constants.h"
18#include "llvm/Function.h"
19#include "llvm/Metadata.h"
20#include "llvm/ADT/SmallVector.h"
21#include "llvm/Support/ErrorHandling.h"
22using namespace llvm;
23
24Value *llvm::MapValue(const Value *V, ValueMapTy &VM) {
25  Value *&VMSlot = VM[V];
26  if (VMSlot) return VMSlot;      // Does it exist in the map yet?
27
28  // NOTE: VMSlot can be invalidated by any reference to VM, which can grow the
29  // DenseMap.  This includes any recursive calls to MapValue.
30
31  // Global values and non-function-local metadata do not need to be seeded into
32  // the ValueMap if they are using the identity mapping.
33  if (isa<GlobalValue>(V) || isa<InlineAsm>(V) || isa<MDString>(V) ||
34      (isa<MDNode>(V) && !dyn_cast<MDNode>(V)->isFunctionLocal()))
35    return VMSlot = const_cast<Value*>(V);
36
37  if (isa<MDNode>(V)) {
38    const MDNode *MD = dyn_cast<MDNode>(V);
39    SmallVector<Value*, 4> Elts;
40    for (unsigned i = 0; i != MD->getNumOperands(); i++)
41      Elts.push_back(MD->getOperand(i) ? MapValue(MD->getOperand(i), VM) : NULL);
42    return VM[V] = MDNode::get(V->getContext(), Elts.data(), Elts.size());
43  }
44
45  Constant *C = const_cast<Constant*>(dyn_cast<Constant>(V));
46  if (C == 0) return 0;
47
48  if (isa<ConstantInt>(C) || isa<ConstantFP>(C) ||
49      isa<ConstantPointerNull>(C) || isa<ConstantAggregateZero>(C) ||
50      isa<UndefValue>(C) || isa<MDString>(C))
51    return VMSlot = C;           // Primitive constants map directly
52
53  if (ConstantArray *CA = dyn_cast<ConstantArray>(C)) {
54    for (User::op_iterator b = CA->op_begin(), i = b, e = CA->op_end();
55         i != e; ++i) {
56      Value *MV = MapValue(*i, VM);
57      if (MV != *i) {
58        // This array must contain a reference to a global, make a new array
59        // and return it.
60        //
61        std::vector<Constant*> Values;
62        Values.reserve(CA->getNumOperands());
63        for (User::op_iterator j = b; j != i; ++j)
64          Values.push_back(cast<Constant>(*j));
65        Values.push_back(cast<Constant>(MV));
66        for (++i; i != e; ++i)
67          Values.push_back(cast<Constant>(MapValue(*i, VM)));
68        return VM[V] = ConstantArray::get(CA->getType(), Values);
69      }
70    }
71    return VM[V] = C;
72  }
73
74  if (ConstantStruct *CS = dyn_cast<ConstantStruct>(C)) {
75    for (User::op_iterator b = CS->op_begin(), i = b, e = CS->op_end();
76         i != e; ++i) {
77      Value *MV = MapValue(*i, VM);
78      if (MV != *i) {
79        // This struct must contain a reference to a global, make a new struct
80        // and return it.
81        //
82        std::vector<Constant*> Values;
83        Values.reserve(CS->getNumOperands());
84        for (User::op_iterator j = b; j != i; ++j)
85          Values.push_back(cast<Constant>(*j));
86        Values.push_back(cast<Constant>(MV));
87        for (++i; i != e; ++i)
88          Values.push_back(cast<Constant>(MapValue(*i, VM)));
89        return VM[V] = ConstantStruct::get(CS->getType(), Values);
90      }
91    }
92    return VM[V] = C;
93  }
94
95  if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
96    std::vector<Constant*> Ops;
97    for (User::op_iterator i = CE->op_begin(), e = CE->op_end(); i != e; ++i)
98      Ops.push_back(cast<Constant>(MapValue(*i, VM)));
99    return VM[V] = CE->getWithOperands(Ops);
100  }
101
102  if (ConstantVector *CV = dyn_cast<ConstantVector>(C)) {
103    for (User::op_iterator b = CV->op_begin(), i = b, e = CV->op_end();
104         i != e; ++i) {
105      Value *MV = MapValue(*i, VM);
106      if (MV != *i) {
107        // This vector value must contain a reference to a global, make a new
108        // vector constant and return it.
109        //
110        std::vector<Constant*> Values;
111        Values.reserve(CV->getNumOperands());
112        for (User::op_iterator j = b; j != i; ++j)
113          Values.push_back(cast<Constant>(*j));
114        Values.push_back(cast<Constant>(MV));
115        for (++i; i != e; ++i)
116          Values.push_back(cast<Constant>(MapValue(*i, VM)));
117        return VM[V] = ConstantVector::get(Values);
118      }
119    }
120    return VM[V] = C;
121  }
122
123  if (BlockAddress *BA = dyn_cast<BlockAddress>(C)) {
124    Function *F = cast<Function>(MapValue(BA->getFunction(), VM));
125    BasicBlock *BB = cast_or_null<BasicBlock>(MapValue(BA->getBasicBlock(),VM));
126    return VM[V] = BlockAddress::get(F, BB ? BB : BA->getBasicBlock());
127  }
128
129  llvm_unreachable("Unknown type of constant!");
130  return 0;
131}
132
133/// RemapInstruction - Convert the instruction operands from referencing the
134/// current values into those specified by ValueMap.
135///
136void llvm::RemapInstruction(Instruction *I, ValueMapTy &ValueMap) {
137  for (User::op_iterator op = I->op_begin(), E = I->op_end(); op != E; ++op) {
138    Value *V = MapValue(*op, ValueMap);
139    assert(V && "Referenced value not in value map!");
140    *op = V;
141  }
142}
143
144