1 //===- CloneFunction.cpp - Clone a function into another function ---------===//
2 //
3 // This file implements the CloneFunctionInto interface, which is used as the
4 // low-level function cloner.  This is used by the CloneFunction and function
5 // inliner to do the dirty work of copying the body of a function around.
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include "llvm/Transforms/Utils/Cloning.h"
10 #include "llvm/iTerminators.h"
11 #include "llvm/DerivedTypes.h"
12 #include "llvm/Function.h"
13 #include "ValueMapper.h"
14 
15 // RemapInstruction - Convert the instruction operands from referencing the
16 // current values into those specified by ValueMap.
17 //
18 static inline void RemapInstruction(Instruction *I,
19                                     std::map<const Value *, Value*> &ValueMap) {
20   for (unsigned op = 0, E = I->getNumOperands(); op != E; ++op) {
21     const Value *Op = I->getOperand(op);
22     Value *V = MapValue(Op, ValueMap);
23 #ifndef NDEBUG
24     if (!V) {
25       std::cerr << "Val = \n" << Op << "Addr = " << (void*)Op;
26       std::cerr << "\nInst = " << I;
27     }
28 #endif
29     assert(V && "Referenced value not in value map!");
30     I->setOperand(op, V);
31   }
32 }
33 
34 // CloneBasicBlock - See comments in Cloning.h
35 BasicBlock *CloneBasicBlock(const BasicBlock *BB,
36                             std::map<const Value*, Value*> &ValueMap,
37                             const char *NameSuffix) {
38   BasicBlock *NewBB = new BasicBlock("");
39   if (BB->hasName()) NewBB->setName(BB->getName()+NameSuffix);
40 
41   // Loop over all instructions copying them over...
42   for (BasicBlock::const_iterator II = BB->begin(), IE = BB->end();
43        II != IE; ++II) {
44     Instruction *NewInst = II->clone();
45     if (II->hasName())
46       NewInst->setName(II->getName()+NameSuffix);
47     NewBB->getInstList().push_back(NewInst);
48     ValueMap[II] = NewInst;                // Add instruction map to value.
49   }
50   return NewBB;
51 }
52 
53 // Clone OldFunc into NewFunc, transforming the old arguments into references to
54 // ArgMap values.
55 //
56 void CloneFunctionInto(Function *NewFunc, const Function *OldFunc,
57                        std::map<const Value*, Value*> &ValueMap,
58                        std::vector<ReturnInst*> &Returns,
59                        const char *NameSuffix) {
60   assert(NameSuffix && "NameSuffix cannot be null!");
61 
62 #ifndef NDEBUG
63   for (Function::const_aiterator I = OldFunc->abegin(), E = OldFunc->aend();
64        I != E; ++I)
65     assert(ValueMap.count(I) && "No mapping from source argument specified!");
66 #endif
67 
68   // Loop over all of the basic blocks in the function, cloning them as
69   // appropriate.  Note that we save BE this way in order to handle cloning of
70   // recursive functions into themselves.
71   //
72   for (Function::const_iterator BI = OldFunc->begin(), BE = OldFunc->end();
73        BI != BE; ++BI) {
74     const BasicBlock &BB = *BI;
75 
76     // Create a new basic block and copy instructions into it!
77     BasicBlock *CBB = CloneBasicBlock(&BB, ValueMap, NameSuffix);
78     NewFunc->getBasicBlockList().push_back(CBB);
79     ValueMap[&BB] = CBB;                       // Add basic block mapping.
80 
81     if (ReturnInst *RI = dyn_cast<ReturnInst>(CBB->getTerminator()))
82       Returns.push_back(RI);
83   }
84 
85   // Loop over all of the instructions in the function, fixing up operand
86   // references as we go.  This uses ValueMap to do all the hard work.
87   //
88   for (Function::const_iterator BB = OldFunc->begin(), BE = OldFunc->end();
89        BB != BE; ++BB) {
90     BasicBlock *NBB = cast<BasicBlock>(ValueMap[BB]);
91 
92     // Loop over all instructions, fixing each one as we find it...
93     for (BasicBlock::iterator II = NBB->begin(); II != NBB->end(); ++II)
94       RemapInstruction(II, ValueMap);
95   }
96 }
97 
98 /// CloneFunction - Return a copy of the specified function, but without
99 /// embedding the function into another module.  Also, any references specified
100 /// in the ValueMap are changed to refer to their mapped value instead of the
101 /// original one.  If any of the arguments to the function are in the ValueMap,
102 /// the arguments are deleted from the resultant function.  The ValueMap is
103 /// updated to include mappings from all of the instructions and basicblocks in
104 /// the function from their old to new values.
105 ///
106 Function *CloneFunction(const Function *F,
107                         std::map<const Value*, Value*> &ValueMap) {
108   std::vector<const Type*> ArgTypes;
109 
110   // The user might be deleting arguments to the function by specifying them in
111   // the ValueMap.  If so, we need to not add the arguments to the arg ty vector
112   //
113   for (Function::const_aiterator I = F->abegin(), E = F->aend(); I != E; ++I)
114     if (ValueMap.count(I) == 0)  // Haven't mapped the argument to anything yet?
115       ArgTypes.push_back(I->getType());
116 
117   // Create a new function type...
118   FunctionType *FTy = FunctionType::get(F->getFunctionType()->getReturnType(),
119                                     ArgTypes, F->getFunctionType()->isVarArg());
120 
121   // Create the new function...
122   Function *NewF = new Function(FTy, F->getLinkage(), F->getName());
123 
124   // Loop over the arguments, copying the names of the mapped arguments over...
125   Function::aiterator DestI = NewF->abegin();
126   for (Function::const_aiterator I = F->abegin(), E = F->aend(); I != E; ++I)
127     if (ValueMap.count(I) == 0) {   // Is this argument preserved?
128       DestI->setName(I->getName()); // Copy the name over...
129       ValueMap[I] = DestI++;        // Add mapping to ValueMap
130     }
131 
132   std::vector<ReturnInst*> Returns;  // Ignore returns cloned...
133   CloneFunctionInto(NewF, F, ValueMap, Returns);
134   return NewF;
135 }
136