lib/Transforms/Utils/ValueMapper.cpp

   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/Type.h"
  17 #include "llvm/Constants.h"
  18 #include "llvm/Function.h"
  19 #include "llvm/Metadata.h"
  20 #include "llvm/ADT/SmallVector.h"
  21 using namespace llvm;
  22
  23 Value *llvm::MapValue(const Value *V, ValueToValueMapTy &VM,
  24                       RemapFlags Flags) {
  25   ValueToValueMapTy::iterator I = VM.find(V);
  26
  27   // If the value already exists in the map, use it.
  28   if (I != VM.end() && I->second) return I->second;
  29
  30   // Global values do not need to be seeded into the VM if they
  31   // are using the identity mapping.
  32   if (isa<GlobalValue>(V) || isa<InlineAsm>(V) || isa<MDString>(V))
  33     return VM[V] = const_cast<Value*>(V);
  34
  35   if (const MDNode *MD = dyn_cast<MDNode>(V)) {
  36     // If this is a module-level metadata and we know that nothing at the module
  37     // level is changing, then use an identity mapping.
  38     if (!MD->isFunctionLocal() && (Flags & RF_NoModuleLevelChanges))
  39       return VM[V] = const_cast<Value*>(V);
  40
  41     // Create a dummy node in case we have a metadata cycle.
  42     MDNode *Dummy = MDNode::getTemporary(V->getContext(), ArrayRef<Value*>());
  43     VM[V] = Dummy;
  44
  45     // Check all operands to see if any need to be remapped.
  46     for (unsigned i = 0, e = MD->getNumOperands(); i != e; ++i) {
  47       Value *OP = MD->getOperand(i);
  48       if (OP == 0 || MapValue(OP, VM, Flags) == OP) continue;
  49
  50       // Ok, at least one operand needs remapping.
  51       SmallVector<Value*, 4> Elts;
  52       Elts.reserve(MD->getNumOperands());
  53       for (i = 0; i != e; ++i) {
  54         Value *Op = MD->getOperand(i);
  55         Elts.push_back(Op ? MapValue(Op, VM, Flags) : 0);
  56       }
  57       MDNode *NewMD = MDNode::get(V->getContext(), Elts);
  58       Dummy->replaceAllUsesWith(NewMD);
  59       VM[V] = NewMD;
  60       MDNode::deleteTemporary(Dummy);
  61       return NewMD;
  62     }
  63
  64     VM[V] = const_cast<Value*>(V);
  65     MDNode::deleteTemporary(Dummy);
  66
  67     // No operands needed remapping.  Use an identity mapping.
  68     return const_cast<Value*>(V);
  69   }
  70
  71   // Okay, this either must be a constant (which may or may not be mappable) or
  72   // is something that is not in the mapping table.
  73   Constant *C = const_cast<Constant*>(dyn_cast<Constant>(V));
  74   if (C == 0)
  75     return 0;
  76
  77   if (BlockAddress *BA = dyn_cast<BlockAddress>(C)) {
  78     Function *F = cast<Function>(MapValue(BA->getFunction(), VM, Flags));
  79     BasicBlock *BB = cast_or_null<BasicBlock>(MapValue(BA->getBasicBlock(), VM,
  80                                                        Flags));
  81     return VM[V] = BlockAddress::get(F, BB ? BB : BA->getBasicBlock());
  82   }
  83
  84   for (unsigned i = 0, e = C->getNumOperands(); i != e; ++i) {
  85     Value *Op = C->getOperand(i);
  86     Value *Mapped = MapValue(Op, VM, Flags);
  87     if (Mapped == C) continue;
  88
  89     // Okay, the operands don't all match.  We've already processed some or all
  90     // of the operands, set them up now.
  91     std::vector<Constant*> Ops;
  92     Ops.reserve(C->getNumOperands());
  93     for (unsigned j = 0; j != i; ++j)
  94       Ops.push_back(cast<Constant>(C->getOperand(i)));
  95     Ops.push_back(cast<Constant>(Mapped));
  96
  97     // Map the rest of the operands that aren't processed yet.
  98     for (++i; i != e; ++i)
  99       Ops.push_back(cast<Constant>(MapValue(C->getOperand(i), VM, Flags)));
 100
 101     if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C))
 102       return VM[V] = CE->getWithOperands(Ops);
 103     if (ConstantArray *CA = dyn_cast<ConstantArray>(C))
 104       return VM[V] = ConstantArray::get(CA->getType(), Ops);
 105     if (ConstantStruct *CS = dyn_cast<ConstantStruct>(C))
 106       return VM[V] = ConstantStruct::get(CS->getType(), Ops);
 107     assert(isa<ConstantVector>(C) && "Unknown mapped constant type");
 108     return VM[V] = ConstantVector::get(Ops);
 109   }
 110
 111   // If we reach here, all of the operands of the constant match.
 112   return VM[V] = C;
 113 }
 114
 115 /// RemapInstruction - Convert the instruction operands from referencing the
 116 /// current values into those specified by VMap.
 117 ///
 118 void llvm::RemapInstruction(Instruction *I, ValueToValueMapTy &VMap,
 119                             RemapFlags Flags) {
 120   // Remap operands.
 121   for (User::op_iterator op = I->op_begin(), E = I->op_end(); op != E; ++op) {
 122     Value *V = MapValue(*op, VMap, Flags);
 123     // If we aren't ignoring missing entries, assert that something happened.
 124     if (V != 0)
 125       *op = V;
 126     else
 127       assert((Flags & RF_IgnoreMissingEntries) &&
 128              "Referenced value not in value map!");
 129   }
 130
 131   // Remap attached metadata.
 132   SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
 133   I->getAllMetadata(MDs);
 134   for (SmallVectorImpl<std::pair<unsigned, MDNode *> >::iterator
 135        MI = MDs.begin(), ME = MDs.end(); MI != ME; ++MI) {
 136     Value *Old = MI->second;
 137     Value *New = MapValue(Old, VMap, Flags);
 138     if (New != Old)
 139       I->setMetadata(MI->first, cast<MDNode>(New));
 140   }
 141 }