ValueMapper.cpp revision f42fae16745c6534c0d9619103dfbb3e299182e1 
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/IntrinsicInst.h"
20#include "llvm/Metadata.h"
21#include "llvm/ADT/SmallVector.h"
22#include "llvm/Support/ErrorHandling.h"
23using namespace llvm;
24
25Value *llvm::MapValue(const Value *V, ValueMapTy &VM) {
26  Value *&VMSlot = VM[V];
27  if (VMSlot) return VMSlot;      // Does it exist in the map yet?
28
29  // NOTE: VMSlot can be invalidated by any reference to VM, which can grow the
30  // DenseMap.  This includes any recursive calls to MapValue.
31
32  // Global values and non-function-local metadata do not need to be seeded into
33  // the ValueMap if they are using the identity mapping.
34  if (isa<GlobalValue>(V) || isa<InlineAsm>(V) || isa<MDString>(V) ||
35      (isa<MDNode>(V) && !dyn_cast<MDNode>(V)->isFunctionLocal()))
36    return VMSlot = const_cast<Value*>(V);
37
38  if (isa<MDNode>(V)) {
39    const MDNode *MD = dyn_cast<MDNode>(V);
40    SmallVector<Value*, 4> Elts;
41    for (unsigned i = 0; i != MD->getNumOperands(); i++)
42      Elts.push_back(MD->getOperand(i) ? MapValue(MD->getOperand(i), VM) : NULL);
43    return VM[V] = MDNode::get(V->getContext(), Elts.data(), Elts.size());
44  }
45
46  Constant *C = const_cast<Constant*>(dyn_cast<Constant>(V));
47  if (C == 0) return 0;
48
49  if (isa<ConstantInt>(C) || isa<ConstantFP>(C) ||
50      isa<ConstantPointerNull>(C) || isa<ConstantAggregateZero>(C) ||
51      isa<UndefValue>(C) || isa<MDString>(C))
52    return VMSlot = C;           // Primitive constants map directly
53
54  if (ConstantArray *CA = dyn_cast<ConstantArray>(C)) {
55    for (User::op_iterator b = CA->op_begin(), i = b, e = CA->op_end();
56         i != e; ++i) {
57      Value *MV = MapValue(*i, VM);
58      if (MV != *i) {
59        // This array must contain a reference to a global, make a new array
60        // and return it.
61        //
62        std::vector<Constant*> Values;
63        Values.reserve(CA->getNumOperands());
64        for (User::op_iterator j = b; j != i; ++j)
65          Values.push_back(cast<Constant>(*j));
66        Values.push_back(cast<Constant>(MV));
67        for (++i; i != e; ++i)
68          Values.push_back(cast<Constant>(MapValue(*i, VM)));
69        return VM[V] = ConstantArray::get(CA->getType(), Values);
70      }
71    }
72    return VM[V] = C;
73  }
74
75  if (ConstantStruct *CS = dyn_cast<ConstantStruct>(C)) {
76    for (User::op_iterator b = CS->op_begin(), i = b, e = CS->op_end();
77         i != e; ++i) {
78      Value *MV = MapValue(*i, VM);
79      if (MV != *i) {
80        // This struct must contain a reference to a global, make a new struct
81        // and return it.
82        //
83        std::vector<Constant*> Values;
84        Values.reserve(CS->getNumOperands());
85        for (User::op_iterator j = b; j != i; ++j)
86          Values.push_back(cast<Constant>(*j));
87        Values.push_back(cast<Constant>(MV));
88        for (++i; i != e; ++i)
89          Values.push_back(cast<Constant>(MapValue(*i, VM)));
90        return VM[V] = ConstantStruct::get(CS->getType(), Values);
91      }
92    }
93    return VM[V] = C;
94  }
95
96  if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
97    std::vector<Constant*> Ops;
98    for (User::op_iterator i = CE->op_begin(), e = CE->op_end(); i != e; ++i)
99      Ops.push_back(cast<Constant>(MapValue(*i, VM)));
100    return VM[V] = CE->getWithOperands(Ops);
101  }
102
103  if (ConstantVector *CV = dyn_cast<ConstantVector>(C)) {
104    for (User::op_iterator b = CV->op_begin(), i = b, e = CV->op_end();
105         i != e; ++i) {
106      Value *MV = MapValue(*i, VM);
107      if (MV != *i) {
108        // This vector value must contain a reference to a global, make a new
109        // vector constant and return it.
110        //
111        std::vector<Constant*> Values;
112        Values.reserve(CV->getNumOperands());
113        for (User::op_iterator j = b; j != i; ++j)
114          Values.push_back(cast<Constant>(*j));
115        Values.push_back(cast<Constant>(MV));
116        for (++i; i != e; ++i)
117          Values.push_back(cast<Constant>(MapValue(*i, VM)));
118        return VM[V] = ConstantVector::get(Values);
119      }
120    }
121    return VM[V] = C;
122  }
123
124  if (BlockAddress *BA = dyn_cast<BlockAddress>(C)) {
125    Function *F = cast<Function>(MapValue(BA->getFunction(), VM));
126    BasicBlock *BB = cast_or_null<BasicBlock>(MapValue(BA->getBasicBlock(),VM));
127    return VM[V] = BlockAddress::get(F, BB ? BB : BA->getBasicBlock());
128  }
129
130  llvm_unreachable("Unknown type of constant!");
131  return 0;
132}
133
134/// RemapInstruction - Convert the instruction operands from referencing the
135/// current values into those specified by ValueMap.
136///
137void llvm::RemapInstruction(Instruction *I, ValueMapTy &ValueMap) {
138  for (User::op_iterator op = I->op_begin(), E = I->op_end(); op != E; ++op) {
139    Value *V = MapValue(*op, ValueMap);
140    assert(V && "Referenced value not in value map!");
141    *op = V;
142  }
143}
144
145