CloneFunction.cpp revision 18961504fc2b299578dba817900a0696cf3ccc4d 
1
2// FIXME: document
3
4#include "llvm/Transforms/Utils/CloneFunction.h"
5#include "llvm/Function.h"
6#include "llvm/BasicBlock.h"
7#include "llvm/Instruction.h"
8#include <map>
9
10// FIXME: This should be merged with FunctionInlining
11
12// RemapInstruction - Convert the instruction operands from referencing the
13// current values into those specified by ValueMap.
14//
15static inline void RemapInstruction(Instruction *I,
16                                    std::map<const Value *, Value*> &ValueMap) {
17  for (unsigned op = 0, E = I->getNumOperands(); op != E; ++op) {
18    const Value *Op = I->getOperand(op);
19    Value *V = ValueMap[Op];
20    if (!V && (isa<GlobalValue>(Op) || isa<Constant>(Op)))
21      continue;  // Globals and constants don't get relocated
22
23#ifndef NDEBUG
24    if (!V) {
25      cerr << "Val = \n" << Op << "Addr = " << (void*)Op;
26      cerr << "\nInst = " << I;
27    }
28#endif
29    assert(V && "Referenced value not in value map!");
30    I->setOperand(op, V);
31  }
32}
33
34// Clone OldFunc into NewFunc, transforming the old arguments into references to
35// ArgMap values.
36//
37void CloneFunctionInto(Function *NewFunc, const Function *OldFunc,
38                       const std::vector<Value*> &ArgMap) {
39  assert(OldFunc->aempty() || !NewFunc->aempty() &&
40         "Synthesization of arguments is not implemented yet!");
41  assert(OldFunc->asize() == ArgMap.size() &&
42         "Improper number of argument values to map specified!");
43
44  // Keep a mapping between the original function's values and the new
45  // duplicated code's values.  This includes all of: Function arguments,
46  // instruction values, constant pool entries, and basic blocks.
47  //
48  std::map<const Value *, Value*> ValueMap;
49
50  // Add all of the function arguments to the mapping...
51  unsigned i = 0;
52  for (Function::const_aiterator I = OldFunc->abegin(), E = OldFunc->aend();
53       I != E; ++I, ++i)
54    ValueMap[I] = ArgMap[i];
55
56
57  // Loop over all of the basic blocks in the function, cloning them as
58  // appropriate.
59  //
60  for (Function::const_iterator BI = OldFunc->begin(), BE = OldFunc->end();
61       BI != BE; ++BI) {
62    const BasicBlock &BB = *BI;
63    assert(BB.getTerminator() && "BasicBlock doesn't have terminator!?!?");
64
65    // Create a new basic block to copy instructions into!
66    BasicBlock *CBB = new BasicBlock(BB.getName(), NewFunc);
67    ValueMap[&BB] = CBB;                       // Add basic block mapping.
68
69    // Loop over all instructions copying them over...
70    for (BasicBlock::const_iterator II = BB.begin(), IE = BB.end();
71         II != IE; ++II) {
72      Instruction *NewInst = II->clone();
73      NewInst->setName(II->getName());       // Name is not cloned...
74      CBB->getInstList().push_back(NewInst);
75      ValueMap[II] = NewInst;                // Add instruction map to value.
76    }
77  }
78
79  // Loop over all of the instructions in the function, fixing up operand
80  // references as we go.  This uses ValueMap to do all the hard work.
81  //
82  for (Function::const_iterator BB = OldFunc->begin(), BE = OldFunc->end();
83       BB != BE; ++BB) {
84    BasicBlock *NBB = cast<BasicBlock>(ValueMap[BB]);
85
86    // Loop over all instructions, fixing each one as we find it...
87    for (BasicBlock::iterator II = NBB->begin(); II != NBB->end(); ++II)
88      RemapInstruction(II, ValueMap);
89  }
90}
91