ExtractFunction.cpp revision 10f22cb1a0f2755050218cd0e07221a0985c6b63 
1//===- ExtractFunction.cpp - Extract a function from Program --------------===//
2//
3// This file implements a method that extracts a function from program, cleans
4// it up, and returns it as a new module.
5//
6//===----------------------------------------------------------------------===//
7
8#include "BugDriver.h"
9#include "llvm/Module.h"
10#include "llvm/PassManager.h"
11#include "llvm/Transforms/IPO.h"
12#include "llvm/Transforms/Scalar.h"
13#include "llvm/Transforms/Utils/Cloning.h"
14#include "llvm/Analysis/Verifier.h"
15#include "llvm/Type.h"
16#include "llvm/Constant.h"
17
18/// extractFunctionFromModule - This method is used to extract the specified
19/// (non-external) function from the current program, slim down the module, and
20/// then return it.  This does not modify Program at all, it modifies a copy,
21/// which it returns.
22Module *BugDriver::extractFunctionFromModule(Function *F) const {
23  Module *Result = CloneModule(Program);
24
25  // Translate from the old module to the new copied module...
26  Module::iterator RFI = Result->begin(); // Get iterator to corresponding fn
27  std::advance(RFI, std::distance(Program->begin(), Module::iterator(F)));
28
29  // In addition to just parsing the input from GCC, we also want to spiff it up
30  // a little bit.  Do this now.
31  //
32  PassManager Passes;
33  Passes.add(createFunctionExtractionPass(RFI));  // Extract the function
34  Passes.add(createGlobalDCEPass());              // Delete unreachable globals
35  Passes.add(createFunctionResolvingPass());      // Delete prototypes
36  Passes.add(createDeadTypeEliminationPass());    // Remove dead types...
37  Passes.add(createVerifierPass());
38  Passes.run(*Result);
39  return Result;
40}
41
42
43/// deleteInstructionFromProgram - This method clones the current Program and
44/// deletes the specified instruction from the cloned module.  It then runs a
45/// series of cleanup passes (ADCE and SimplifyCFG) to eliminate any code which
46/// depends on the value.  The modified module is then returned.
47///
48Module *BugDriver::deleteInstructionFromProgram(Instruction *I,
49                                                unsigned Simplification) const {
50  Module *Result = CloneModule(Program);
51
52  BasicBlock *PBB = I->getParent();
53  Function *PF = PBB->getParent();
54
55  Module::iterator RFI = Result->begin(); // Get iterator to corresponding fn
56  std::advance(RFI, std::distance(Program->begin(), Module::iterator(PF)));
57
58  Function::iterator RBI = RFI->begin();  // Get iterator to corresponding BB
59  std::advance(RBI, std::distance(PF->begin(), Function::iterator(PBB)));
60
61  BasicBlock::iterator RI = RBI->begin(); // Get iterator to corresponding inst
62  std::advance(RI, std::distance(PBB->begin(), BasicBlock::iterator(I)));
63  I = RI;                                 // Got the corresponding instruction!
64
65  // If this instruction produces a value, replace any users with null values
66  if (I->getType() != Type::VoidTy)
67    I->replaceAllUsesWith(Constant::getNullValue(I->getType()));
68
69  // Remove the instruction from the program.
70  I->getParent()->getInstList().erase(I);
71
72  // In addition to just parsing the input from GCC, we also want to spiff it up
73  // a little bit.  Do this now.
74  //
75  PassManager Passes;
76  if (Simplification > 2)
77    Passes.add(createAggressiveDCEPass());          // Remove dead code...
78  //Passes.add(createInstructionCombiningPass());
79  if (Simplification > 1)
80    Passes.add(createDeadCodeEliminationPass());
81  if (Simplification)
82    Passes.add(createCFGSimplificationPass());      // Delete dead control flow
83
84  Passes.add(createVerifierPass());
85  Passes.run(*Result);
86  return Result;
87}
88
89/// performFinalCleanups - This method clones the current Program and performs
90/// a series of cleanups intended to get rid of extra cruft on the module
91/// before handing it to the user...
92///
93Module *BugDriver::performFinalCleanups() const {
94  PassManager CleanupPasses;
95  CleanupPasses.add(createFunctionResolvingPass());
96  CleanupPasses.add(createGlobalDCEPass());
97  CleanupPasses.add(createVerifierPass());
98  Module *M = CloneModule(Program);
99  CleanupPasses.run(*M);
100  return M;
101}
102