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/Type.h"
15 #include "llvm/Constant.h"
16 
17 /// extractFunctionFromModule - This method is used to extract the specified
18 /// (non-external) function from the current program, slim down the module, and
19 /// then return it.  This does not modify Program at all, it modifies a copy,
20 /// which it returns.
21 Module *BugDriver::extractFunctionFromModule(Function *F) const {
22   Module *Result = CloneModule(Program);
23 
24   // Translate from the old module to the new copied module...
25   Module::iterator RFI = Result->begin(); // Get iterator to corresponding fn
26   std::advance(RFI, std::distance(Program->begin(), Module::iterator(F)));
27 
28   // In addition to just parsing the input from GCC, we also want to spiff it up
29   // a little bit.  Do this now.
30   //
31   PassManager Passes;
32   Passes.add(createFunctionExtractionPass(RFI));  // Extract the function
33   Passes.add(createGlobalDCEPass());              // Delete unreachable globals
34   Passes.add(createFunctionResolvingPass());      // Delete prototypes
35   Passes.add(createDeadTypeEliminationPass());    // Remove dead types...
36   Passes.run(*Result);
37   return Result;
38 }
39 
40 
41 /// deleteInstructionFromProgram - This method clones the current Program and
42 /// deletes the specified instruction from the cloned module.  It then runs a
43 /// series of cleanup passes (ADCE and SimplifyCFG) to eliminate any code which
44 /// depends on the value.  The modified module is then returned.
45 ///
46 Module *BugDriver::deleteInstructionFromProgram(Instruction *I,
47                                                 unsigned Simplification) const {
48   Module *Result = CloneModule(Program);
49 
50   BasicBlock *PBB = I->getParent();
51   Function *PF = PBB->getParent();
52 
53   Module::iterator RFI = Result->begin(); // Get iterator to corresponding fn
54   std::advance(RFI, std::distance(Program->begin(), Module::iterator(PF)));
55 
56   Function::iterator RBI = RFI->begin();  // Get iterator to corresponding BB
57   std::advance(RBI, std::distance(PF->begin(), Function::iterator(PBB)));
58 
59   BasicBlock::iterator RI = RBI->begin(); // Get iterator to corresponding inst
60   std::advance(RI, std::distance(PBB->begin(), BasicBlock::iterator(I)));
61   I = RI;                                 // Got the corresponding instruction!
62 
63   // If this instruction produces a value, replace any users with null values
64   if (I->getType() != Type::VoidTy)
65     I->replaceAllUsesWith(Constant::getNullValue(I->getType()));
66 
67   // Remove the instruction from the program.
68   I->getParent()->getInstList().erase(I);
69 
70   // In addition to just parsing the input from GCC, we also want to spiff it up
71   // a little bit.  Do this now.
72   //
73   PassManager Passes;
74   if (Simplification > 2)
75     Passes.add(createAggressiveDCEPass());          // Remove dead code...
76   //Passes.add(createInstructionCombiningPass());
77   if (Simplification > 1)
78     Passes.add(createDeadCodeEliminationPass());
79   if (Simplification)
80     Passes.add(createCFGSimplificationPass());      // Delete dead control flow
81   Passes.run(*Result);
82   return Result;
83 }
84