ProfilingUtils.cpp revision 467dd2ec6192fca6fe1d2a4b339fbc9b45ca3b17 
1//===- ProfilingUtils.cpp - Helper functions shared by profilers ----------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file was developed by the LLVM research group and is distributed under
6// the University of Illinois Open Source License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This files 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/Module.h"
22
23void llvm::InsertProfilingInitCall(Function *MainFn, const char *FnName,
24                                   GlobalValue *Array) {
25  const Type *ArgVTy = PointerType::get(PointerType::get(Type::SByteTy));
26  const Type *UIntPtr = PointerType::get(Type::UIntTy);
27  Module &M = *MainFn->getParent();
28  Function *InitFn = M.getOrInsertFunction(FnName, Type::IntTy, Type::IntTy,
29                                           ArgVTy, UIntPtr, Type::UIntTy, 0);
30
31  // This could force argc and argv into programs that wouldn't otherwise have
32  // them, but instead we just pass null values in.
33  std::vector<Value*> Args(4);
34  Args[0] = Constant::getNullValue(Type::IntTy);
35  Args[1] = Constant::getNullValue(ArgVTy);
36
37  // Skip over any allocas in the entry block.
38  BasicBlock *Entry = MainFn->begin();
39  BasicBlock::iterator InsertPos = Entry->begin();
40  while (isa<AllocaInst>(InsertPos)) ++InsertPos;
41
42  ConstantPointerRef *ArrayCPR = ConstantPointerRef::get(Array);
43  std::vector<Constant*> GEPIndices(2, Constant::getNullValue(Type::LongTy));
44  Args[2] = ConstantExpr::getGetElementPtr(ArrayCPR, GEPIndices);
45
46  unsigned NumElements =
47    cast<ArrayType>(Array->getType()->getElementType())->getNumElements();
48  Args[3] = ConstantUInt::get(Type::UIntTy, NumElements);
49
50  Instruction *InitCall = new CallInst(InitFn, Args, "newargc", InsertPos);
51
52  // If argc or argv are not available in main, just pass null values in.
53  Function::aiterator AI;
54  switch (MainFn->asize()) {
55  default:
56  case 2:
57    AI = MainFn->abegin(); ++AI;
58    if (AI->getType() != ArgVTy) {
59      InitCall->setOperand(2, new CastInst(AI, ArgVTy, "argv.cast", InitCall));
60    } else {
61      InitCall->setOperand(2, AI);
62    }
63
64  case 1:
65    AI = MainFn->abegin();
66    // If the program looked at argc, have it look at the return value of the
67    // init call instead.
68    if (AI->getType() != Type::IntTy) {
69      if (!AI->use_empty())
70        AI->replaceAllUsesWith(new CastInst(InitCall, AI->getType(), "",
71                                            InsertPos));
72      InitCall->setOperand(1, new CastInst(AI, Type::IntTy, "argc.cast",
73                                           InitCall));
74    } else {
75      AI->replaceAllUsesWith(InitCall);
76      InitCall->setOperand(1, AI);
77    }
78
79  case 0: break;
80  }
81}
82
83void llvm::IncrementCounterInBlock(BasicBlock *BB, unsigned CounterNum,
84                                   ConstantPointerRef *CounterArray) {
85  // Insert the increment after any alloca or PHI instructions...
86  BasicBlock::iterator InsertPos = BB->begin();
87  while (isa<AllocaInst>(InsertPos) || isa<PHINode>(InsertPos))
88    ++InsertPos;
89
90  // Create the getelementptr constant expression
91  std::vector<Constant*> Indices(2);
92  Indices[0] = Constant::getNullValue(Type::LongTy);
93  Indices[1] = ConstantSInt::get(Type::LongTy, CounterNum);
94  Constant *ElementPtr = ConstantExpr::getGetElementPtr(CounterArray, Indices);
95
96  // Load, increment and store the value back.
97  Value *OldVal = new LoadInst(ElementPtr, "OldFuncCounter", InsertPos);
98  Value *NewVal = BinaryOperator::create(Instruction::Add, OldVal,
99                                         ConstantInt::get(Type::UIntTy, 1),
100                                         "NewFuncCounter", InsertPos);
101  new StoreInst(NewVal, ElementPtr, InsertPos);
102}
103