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/Constants.h"
  17 #include "llvm/Function.h"
  18 #include "llvm/Instructions.h"
  19 #include "llvm/Metadata.h"
  20 using namespace llvm;
  21
  22 // Out of line method to get vtable etc for class.
  23 void ValueMapTypeRemapper::Anchor() {}
  24
  25 Value *llvm::MapValue(const Value *V, ValueToValueMapTy &VM, RemapFlags Flags,
  26                       ValueMapTypeRemapper *TypeMapper) {
  27   ValueToValueMapTy::iterator I = VM.find(V);
  28
  29   // If the value already exists in the map, use it.
  30   if (I != VM.end() && I->second) return I->second;
  31
  32   // Global values do not need to be seeded into the VM if they
  33   // are using the identity mapping.
  34   if (isa<GlobalValue>(V) || isa<InlineAsm>(V) || isa<MDString>(V))
  35     return VM[V] = const_cast<Value*>(V);
  36
  37   if (const MDNode *MD = dyn_cast<MDNode>(V)) {
  38     // If this is a module-level metadata and we know that nothing at the module
  39     // level is changing, then use an identity mapping.
  40     if (!MD->isFunctionLocal() && (Flags & RF_NoModuleLevelChanges))
  41       return VM[V] = const_cast<Value*>(V);
  42
  43     // Create a dummy node in case we have a metadata cycle.
  44     MDNode *Dummy = MDNode::getTemporary(V->getContext(), ArrayRef<Value*>());
  45     VM[V] = Dummy;
  46
  47     // Check all operands to see if any need to be remapped.
  48     for (unsigned i = 0, e = MD->getNumOperands(); i != e; ++i) {
  49       Value *OP = MD->getOperand(i);
  50       if (OP == 0 || MapValue(OP, VM, Flags, TypeMapper) == OP) continue;
  51
  52       // Ok, at least one operand needs remapping.
  53       SmallVector<Value*, 4> Elts;
  54       Elts.reserve(MD->getNumOperands());
  55       for (i = 0; i != e; ++i) {
  56         Value *Op = MD->getOperand(i);
  57         Elts.push_back(Op ? MapValue(Op, VM, Flags, TypeMapper) : 0);
  58       }
  59       MDNode *NewMD = MDNode::get(V->getContext(), Elts);
  60       Dummy->replaceAllUsesWith(NewMD);
  61       VM[V] = NewMD;
  62       MDNode::deleteTemporary(Dummy);
  63       return NewMD;
  64     }
  65
  66     VM[V] = const_cast<Value*>(V);
  67     MDNode::deleteTemporary(Dummy);
  68
  69     // No operands needed remapping.  Use an identity mapping.
  70     return const_cast<Value*>(V);
  71   }
  72
  73   // Okay, this either must be a constant (which may or may not be mappable) or
  74   // is something that is not in the mapping table.
  75   Constant *C = const_cast<Constant*>(dyn_cast<Constant>(V));
  76   if (C == 0)
  77     return 0;
  78
  79   if (BlockAddress *BA = dyn_cast<BlockAddress>(C)) {
  80     Function *F =
  81       cast<Function>(MapValue(BA->getFunction(), VM, Flags, TypeMapper));
  82     BasicBlock *BB = cast_or_null<BasicBlock>(MapValue(BA->getBasicBlock(), VM,
  83                                                        Flags, TypeMapper));
  84     return VM[V] = BlockAddress::get(F, BB ? BB : BA->getBasicBlock());
  85   }
  86
  87   // Otherwise, we have some other constant to remap.  Start by checking to see
  88   // if all operands have an identity remapping.
  89   unsigned OpNo = 0, NumOperands = C->getNumOperands();
  90   Value *Mapped = 0;
  91   for (; OpNo != NumOperands; ++OpNo) {
  92     Value *Op = C->getOperand(OpNo);
  93     Mapped = MapValue(Op, VM, Flags, TypeMapper);
  94     if (Mapped != C) break;
  95   }
  96
  97   // See if the type mapper wants to remap the type as well.
  98   Type *NewTy = C->getType();
  99   if (TypeMapper)
 100     NewTy = TypeMapper->remapType(NewTy);
 101
 102   // If the result type and all operands match up, then just insert an identity
 103   // mapping.
 104   if (OpNo == NumOperands && NewTy == C->getType())
 105     return VM[V] = C;
 106
 107   // Okay, we need to create a new constant.  We've already processed some or
 108   // all of the operands, set them all up now.
 109   SmallVector<Constant*, 8> Ops;
 110   Ops.reserve(NumOperands);
 111   for (unsigned j = 0; j != OpNo; ++j)
 112     Ops.push_back(cast<Constant>(C->getOperand(j)));
 113
 114   // If one of the operands mismatch, push it and the other mapped operands.
 115   if (OpNo != NumOperands) {
 116     Ops.push_back(cast<Constant>(Mapped));
 117
 118     // Map the rest of the operands that aren't processed yet.
 119     for (++OpNo; OpNo != NumOperands; ++OpNo)
 120       Ops.push_back(MapValue(cast<Constant>(C->getOperand(OpNo)), VM,
 121                              Flags, TypeMapper));
 122   }
 123
 124   if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C))
 125     return VM[V] = CE->getWithOperands(Ops, NewTy);
 126   if (isa<ConstantArray>(C))
 127     return VM[V] = ConstantArray::get(cast<ArrayType>(NewTy), Ops);
 128   if (isa<ConstantStruct>(C))
 129     return VM[V] = ConstantStruct::get(cast<StructType>(NewTy), Ops);
 130   if (isa<ConstantVector>(C))
 131     return VM[V] = ConstantVector::get(Ops);
 132   // If this is a no-operand constant, it must be because the type was remapped.
 133   if (isa<UndefValue>(C))
 134     return VM[V] = UndefValue::get(NewTy);
 135   if (isa<ConstantAggregateZero>(C))
 136     return VM[V] = ConstantAggregateZero::get(NewTy);
 137   assert(isa<ConstantPointerNull>(C));
 138   return VM[V] = ConstantPointerNull::get(cast<PointerType>(NewTy));
 139 }
 140
 141 /// RemapInstruction - Convert the instruction operands from referencing the
 142 /// current values into those specified by VMap.
 143 ///
 144 void llvm::RemapInstruction(Instruction *I, ValueToValueMapTy &VMap,
 145                             RemapFlags Flags, ValueMapTypeRemapper *TypeMapper){
 146   // Remap operands.
 147   for (User::op_iterator op = I->op_begin(), E = I->op_end(); op != E; ++op) {
 148     Value *V = MapValue(*op, VMap, Flags, TypeMapper);
 149     // If we aren't ignoring missing entries, assert that something happened.
 150     if (V != 0)
 151       *op = V;
 152     else
 153       assert((Flags & RF_IgnoreMissingEntries) &&
 154              "Referenced value not in value map!");
 155   }
 156
 157   // Remap phi nodes' incoming blocks.
 158   if (PHINode *PN = dyn_cast<PHINode>(I)) {
 159     for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
 160       Value *V = MapValue(PN->getIncomingBlock(i), VMap, Flags);
 161       // If we aren't ignoring missing entries, assert that something happened.
 162       if (V != 0)
 163         PN->setIncomingBlock(i, cast<BasicBlock>(V));
 164       else
 165         assert((Flags & RF_IgnoreMissingEntries) &&
 166                "Referenced block not in value map!");
 167     }
 168   }
 169
 170   // Remap attached metadata.
 171   SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
 172   I->getAllMetadata(MDs);
 173   for (SmallVectorImpl<std::pair<unsigned, MDNode *> >::iterator
 174        MI = MDs.begin(), ME = MDs.end(); MI != ME; ++MI) {
 175     MDNode *Old = MI->second;
 176     MDNode *New = MapValue(Old, VMap, Flags, TypeMapper);
 177     if (New != Old)
 178       I->setMetadata(MI->first, New);
 179   }
 180
 181   // If the instruction's type is being remapped, do so now.
 182   if (TypeMapper)
 183     I->mutateType(TypeMapper->remapType(I->getType()));
 184 }