ProfilingUtils.cpp revision 508955156a25a9abc470a29e1760aa176d341cf9 
1//===- ProfilingUtils.cpp - Helper functions shared by profilers ----------===//
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 implements a few helper functions which are used by profile
11// instrumentation code to instrument the code.  This allows the profiler pass
12// to worry about *what* to insert, and these functions take care of *how* to do
13// it.
14//
15//===----------------------------------------------------------------------===//
16
17#include "ProfilingUtils.h"
18#include "llvm/Constants.h"
19#include "llvm/DerivedTypes.h"
20#include "llvm/Instructions.h"
21#include "llvm/LLVMContext.h"
22#include "llvm/Module.h"
23
24void llvm::InsertProfilingInitCall(Function *MainFn, const char *FnName,
25                                   GlobalValue *Array) {
26  LLVMContext* Context = MainFn->getContext();
27  const Type *ArgVTy =
28    Context->getPointerTypeUnqual(Context->getPointerTypeUnqual(Type::Int8Ty));
29  const PointerType *UIntPtr = Context->getPointerTypeUnqual(Type::Int32Ty);
30  Module &M = *MainFn->getParent();
31  Constant *InitFn = M.getOrInsertFunction(FnName, Type::Int32Ty, Type::Int32Ty,
32                                           ArgVTy, UIntPtr, Type::Int32Ty,
33                                           (Type *)0);
34
35  // This could force argc and argv into programs that wouldn't otherwise have
36  // them, but instead we just pass null values in.
37  std::vector<Value*> Args(4);
38  Args[0] = Context->getNullValue(Type::Int32Ty);
39  Args[1] = Context->getNullValue(ArgVTy);
40
41  // Skip over any allocas in the entry block.
42  BasicBlock *Entry = MainFn->begin();
43  BasicBlock::iterator InsertPos = Entry->begin();
44  while (isa<AllocaInst>(InsertPos)) ++InsertPos;
45
46  std::vector<Constant*> GEPIndices(2, Context->getNullValue(Type::Int32Ty));
47  unsigned NumElements = 0;
48  if (Array) {
49    Args[2] = Context->getConstantExprGetElementPtr(Array, &GEPIndices[0],
50                                             GEPIndices.size());
51    NumElements =
52      cast<ArrayType>(Array->getType()->getElementType())->getNumElements();
53  } else {
54    // If this profiling instrumentation doesn't have a constant array, just
55    // pass null.
56    Args[2] = Context->getConstantPointerNull(UIntPtr);
57  }
58  Args[3] = Context->getConstantInt(Type::Int32Ty, NumElements);
59
60  Instruction *InitCall = CallInst::Create(InitFn, Args.begin(), Args.end(),
61                                           "newargc", InsertPos);
62
63  // If argc or argv are not available in main, just pass null values in.
64  Function::arg_iterator AI;
65  switch (MainFn->arg_size()) {
66  default:
67  case 2:
68    AI = MainFn->arg_begin(); ++AI;
69    if (AI->getType() != ArgVTy) {
70      Instruction::CastOps opcode = CastInst::getCastOpcode(AI, false, ArgVTy,
71                                                            false);
72      InitCall->setOperand(2,
73          CastInst::Create(opcode, AI, ArgVTy, "argv.cast", InitCall));
74    } else {
75      InitCall->setOperand(2, AI);
76    }
77    /* FALL THROUGH */
78
79  case 1:
80    AI = MainFn->arg_begin();
81    // If the program looked at argc, have it look at the return value of the
82    // init call instead.
83    if (AI->getType() != Type::Int32Ty) {
84      Instruction::CastOps opcode;
85      if (!AI->use_empty()) {
86        opcode = CastInst::getCastOpcode(InitCall, true, AI->getType(), true);
87        AI->replaceAllUsesWith(
88          CastInst::Create(opcode, InitCall, AI->getType(), "", InsertPos));
89      }
90      opcode = CastInst::getCastOpcode(AI, true, Type::Int32Ty, true);
91      InitCall->setOperand(1,
92          CastInst::Create(opcode, AI, Type::Int32Ty, "argc.cast", InitCall));
93    } else {
94      AI->replaceAllUsesWith(InitCall);
95      InitCall->setOperand(1, AI);
96    }
97
98  case 0: break;
99  }
100}
101
102void llvm::IncrementCounterInBlock(BasicBlock *BB, unsigned CounterNum,
103                                   GlobalValue *CounterArray) {
104  LLVMContext* Context = BB->getContext();
105
106  // Insert the increment after any alloca or PHI instructions...
107  BasicBlock::iterator InsertPos = BB->getFirstNonPHI();
108  while (isa<AllocaInst>(InsertPos))
109    ++InsertPos;
110
111  // Create the getelementptr constant expression
112  std::vector<Constant*> Indices(2);
113  Indices[0] = Context->getNullValue(Type::Int32Ty);
114  Indices[1] = Context->getConstantInt(Type::Int32Ty, CounterNum);
115  Constant *ElementPtr =
116    Context->getConstantExprGetElementPtr(CounterArray, &Indices[0],
117                                          Indices.size());
118
119  // Load, increment and store the value back.
120  Value *OldVal = new LoadInst(ElementPtr, "OldFuncCounter", InsertPos);
121  Value *NewVal = BinaryOperator::Create(Instruction::Add, OldVal,
122                                      Context->getConstantInt(Type::Int32Ty, 1),
123                                         "NewFuncCounter", InsertPos);
124  new StoreInst(NewVal, ElementPtr, InsertPos);
125}
126