ValueMapper.cpp revision 7a0370f66ab5739f42ffe822f33494e0de9b182b 
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/GlobalValue.h"
18#include "llvm/Instruction.h"
19#include "llvm/MDNode.h"
20#include "llvm/ADT/SmallVector.h"
21using namespace llvm;
22
23Value *llvm::MapValue(const Value *V, ValueMapTy &VM) {
24  Value *&VMSlot = VM[V];
25  if (VMSlot) return VMSlot;      // Does it exist in the map yet?
26
27  // NOTE: VMSlot can be invalidated by any reference to VM, which can grow the
28  // DenseMap.  This includes any recursive calls to MapValue.
29
30  // Global values do not need to be seeded into the ValueMap if they are using
31  // the identity mapping.
32  if (isa<GlobalValue>(V) || isa<InlineAsm>(V))
33    return VMSlot = const_cast<Value*>(V);
34
35  if (Constant *C = const_cast<Constant*>(dyn_cast<Constant>(V))) {
36    if (isa<ConstantInt>(C) || isa<ConstantFP>(C) ||
37        isa<ConstantPointerNull>(C) || isa<ConstantAggregateZero>(C) ||
38        isa<UndefValue>(C) || isa<MDString>(C))
39      return VMSlot = C;           // Primitive constants map directly
40    else if (ConstantArray *CA = dyn_cast<ConstantArray>(C)) {
41      for (User::op_iterator b = CA->op_begin(), i = b, e = CA->op_end();
42           i != e; ++i) {
43        Value *MV = MapValue(*i, VM);
44        if (MV != *i) {
45          // This array must contain a reference to a global, make a new array
46          // and return it.
47          //
48          std::vector<Constant*> Values;
49          Values.reserve(CA->getNumOperands());
50          for (User::op_iterator j = b; j != i; ++j)
51            Values.push_back(cast<Constant>(*j));
52          Values.push_back(cast<Constant>(MV));
53          for (++i; i != e; ++i)
54            Values.push_back(cast<Constant>(MapValue(*i, VM)));
55          return VM[V] = ConstantArray::get(CA->getType(), Values);
56        }
57      }
58      return VM[V] = C;
59
60    } else if (ConstantStruct *CS = dyn_cast<ConstantStruct>(C)) {
61      for (User::op_iterator b = CS->op_begin(), i = b, e = CS->op_end();
62           i != e; ++i) {
63        Value *MV = MapValue(*i, VM);
64        if (MV != *i) {
65          // This struct must contain a reference to a global, make a new struct
66          // and return it.
67          //
68          std::vector<Constant*> Values;
69          Values.reserve(CS->getNumOperands());
70          for (User::op_iterator j = b; j != i; ++j)
71            Values.push_back(cast<Constant>(*j));
72          Values.push_back(cast<Constant>(MV));
73          for (++i; i != e; ++i)
74            Values.push_back(cast<Constant>(MapValue(*i, VM)));
75          return VM[V] = ConstantStruct::get(CS->getType(), Values);
76        }
77      }
78      return VM[V] = C;
79
80    } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
81      std::vector<Constant*> Ops;
82      for (User::op_iterator i = CE->op_begin(), e = CE->op_end(); i != e; ++i)
83        Ops.push_back(cast<Constant>(MapValue(*i, VM)));
84      return VM[V] = CE->getWithOperands(Ops);
85    } else if (ConstantVector *CP = dyn_cast<ConstantVector>(C)) {
86      for (User::op_iterator b = CP->op_begin(), i = b, e = CP->op_end();
87           i != e; ++i) {
88        Value *MV = MapValue(*i, VM);
89        if (MV != *i) {
90          // This vector value must contain a reference to a global, make a new
91          // vector constant and return it.
92          //
93          std::vector<Constant*> Values;
94          Values.reserve(CP->getNumOperands());
95          for (User::op_iterator j = b; j != i; ++j)
96            Values.push_back(cast<Constant>(*j));
97          Values.push_back(cast<Constant>(MV));
98          for (++i; i != e; ++i)
99            Values.push_back(cast<Constant>(MapValue(*i, VM)));
100          return VM[V] = ConstantVector::get(Values);
101        }
102      }
103      return VM[V] = C;
104
105    } else if (MDNode *N = dyn_cast<MDNode>(C)) {
106      for (MDNode::const_elem_iterator b = N->elem_begin(), i = b,
107             e = N->elem_end(); i != e; ++i) {
108        if (!*i) continue;
109
110        Value *MV = MapValue(*i, VM);
111        if (MV != *i) {
112          // This MDNode must contain a reference to a global, make a new MDNode
113          // and return it.
114	  SmallVector<Value*, 8> Values;
115          Values.reserve(N->getNumElements());
116          for (MDNode::const_elem_iterator j = b; j != i; ++j)
117            Values.push_back(*j);
118          Values.push_back(MV);
119          for (++i; i != e; ++i)
120            Values.push_back(MapValue(*i, VM));
121          return VM[V] = MDNode::get(Values.data(), Values.size());
122        }
123      }
124      return VM[V] = C;
125
126    } else {
127      assert(0 && "Unknown type of constant!");
128    }
129  }
130
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