ValueMapper.cpp revision 5e665f559419c7f58a4fd9360cd488f065505c44 
1//===- ValueMapper.cpp - Interface shared by lib/Transforms/Utils ---------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file was developed by the LLVM research group and is distributed under
6// the University of Illinois Open Source 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 "ValueMapper.h"
16#include "llvm/Constants.h"
17#include "llvm/GlobalValue.h"
18#include "llvm/Instruction.h"
19using namespace llvm;
20
21Value *llvm::MapValue(const Value *V, ValueMapTy &VM) {
22  Value *&VMSlot = VM[V];
23  if (VMSlot) return VMSlot;      // Does it exist in the map yet?
24
25  // NOTE: VMSlot can be invalidated by any reference to VM, which can grow the
26  // DenseMap.  This includes any recursive calls to MapValue.
27
28  // Global values do not need to be seeded into the ValueMap if they are using
29  // the identity mapping.
30  if (isa<GlobalValue>(V) || isa<InlineAsm>(V))
31    return VMSlot = const_cast<Value*>(V);
32
33  if (Constant *C = const_cast<Constant*>(dyn_cast<Constant>(V))) {
34    if (isa<ConstantInt>(C) || isa<ConstantFP>(C) ||
35        isa<ConstantPointerNull>(C) || isa<ConstantAggregateZero>(C) ||
36        isa<UndefValue>(C))
37      return VMSlot = C;           // Primitive constants map directly
38    else if (ConstantArray *CA = dyn_cast<ConstantArray>(C)) {
39      for (unsigned i = 0, e = CA->getNumOperands(); i != e; ++i) {
40        Value *MV = MapValue(CA->getOperand(i), VM);
41        if (MV != CA->getOperand(i)) {
42          // This array must contain a reference to a global, make a new array
43          // and return it.
44          //
45          std::vector<Constant*> Values;
46          Values.reserve(CA->getNumOperands());
47          for (unsigned j = 0; j != i; ++j)
48            Values.push_back(CA->getOperand(j));
49          Values.push_back(cast<Constant>(MV));
50          for (++i; i != e; ++i)
51            Values.push_back(cast<Constant>(MapValue(CA->getOperand(i), VM)));
52          return VM[V] = ConstantArray::get(CA->getType(), Values);
53        }
54      }
55      return VM[V] = C;
56
57    } else if (ConstantStruct *CS = dyn_cast<ConstantStruct>(C)) {
58      for (unsigned i = 0, e = CS->getNumOperands(); i != e; ++i) {
59        Value *MV = MapValue(CS->getOperand(i), VM);
60        if (MV != CS->getOperand(i)) {
61          // This struct must contain a reference to a global, make a new struct
62          // and return it.
63          //
64          std::vector<Constant*> Values;
65          Values.reserve(CS->getNumOperands());
66          for (unsigned j = 0; j != i; ++j)
67            Values.push_back(CS->getOperand(j));
68          Values.push_back(cast<Constant>(MV));
69          for (++i; i != e; ++i)
70            Values.push_back(cast<Constant>(MapValue(CS->getOperand(i), VM)));
71          return VM[V] = ConstantStruct::get(CS->getType(), Values);
72        }
73      }
74      return VM[V] = C;
75
76    } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
77      std::vector<Constant*> Ops;
78      for (unsigned i = 0, e = CE->getNumOperands(); i != e; ++i)
79        Ops.push_back(cast<Constant>(MapValue(CE->getOperand(i), VM)));
80      return VM[V] = CE->getWithOperands(Ops);
81    } else if (ConstantPacked *CP = dyn_cast<ConstantPacked>(C)) {
82      for (unsigned i = 0, e = CP->getNumOperands(); i != e; ++i) {
83        Value *MV = MapValue(CP->getOperand(i), VM);
84        if (MV != CP->getOperand(i)) {
85          // This packed value must contain a reference to a global, make a new
86          // packed constant and return it.
87          //
88          std::vector<Constant*> Values;
89          Values.reserve(CP->getNumOperands());
90          for (unsigned j = 0; j != i; ++j)
91            Values.push_back(CP->getOperand(j));
92          Values.push_back(cast<Constant>(MV));
93          for (++i; i != e; ++i)
94            Values.push_back(cast<Constant>(MapValue(CP->getOperand(i), VM)));
95          return VM[V] = ConstantPacked::get(Values);
96        }
97      }
98      return VMSlot = C;
99
100    } else {
101      assert(0 && "Unknown type of constant!");
102    }
103  }
104
105  return 0;
106}
107
108/// RemapInstruction - Convert the instruction operands from referencing the
109/// current values into those specified by ValueMap.
110///
111void llvm::RemapInstruction(Instruction *I, ValueMapTy &ValueMap) {
112  for (unsigned op = 0, E = I->getNumOperands(); op != E; ++op) {
113    const Value *Op = I->getOperand(op);
114    Value *V = MapValue(Op, ValueMap);
115    assert(V && "Referenced value not in value map!");
116    I->setOperand(op, V);
117  }
118}
119