ProfilingUtils.cpp revision b83eb6447ba155342598f0fabe1f08f5baa9164a 
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 PointerType *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,
30                                           (Type *)0);
31
32  // This could force argc and argv into programs that wouldn't otherwise have
33  // them, but instead we just pass null values in.
34  std::vector<Value*> Args(4);
35  Args[0] = Constant::getNullValue(Type::IntTy);
36  Args[1] = Constant::getNullValue(ArgVTy);
37
38  // Skip over any allocas in the entry block.
39  BasicBlock *Entry = MainFn->begin();
40  BasicBlock::iterator InsertPos = Entry->begin();
41  while (isa<AllocaInst>(InsertPos)) ++InsertPos;
42
43  std::vector<Constant*> GEPIndices(2, Constant::getNullValue(Type::IntTy));
44  unsigned NumElements = 0;
45  if (Array) {
46    Args[2] = ConstantExpr::getGetElementPtr(Array, GEPIndices);
47    NumElements =
48      cast<ArrayType>(Array->getType()->getElementType())->getNumElements();
49  } else {
50    // If this profiling instrumentation doesn't have a constant array, just
51    // pass null.
52    Args[2] = ConstantPointerNull::get(UIntPtr);
53  }
54  Args[3] = ConstantInt::get(Type::UIntTy, NumElements);
55
56  Instruction *InitCall = new CallInst(InitFn, Args, "newargc", InsertPos);
57
58  // If argc or argv are not available in main, just pass null values in.
59  Function::arg_iterator AI;
60  switch (MainFn->arg_size()) {
61  default:
62  case 2:
63    AI = MainFn->arg_begin(); ++AI;
64    if (AI->getType() != ArgVTy) {
65      InitCall->setOperand(2, new CastInst(AI, ArgVTy, "argv.cast", InitCall));
66    } else {
67      InitCall->setOperand(2, AI);
68    }
69
70  case 1:
71    AI = MainFn->arg_begin();
72    // If the program looked at argc, have it look at the return value of the
73    // init call instead.
74    if (AI->getType() != Type::IntTy) {
75      if (!AI->use_empty())
76        AI->replaceAllUsesWith(new CastInst(InitCall, AI->getType(), "",
77                                            InsertPos));
78      InitCall->setOperand(1, new CastInst(AI, Type::IntTy, "argc.cast",
79                                           InitCall));
80    } else {
81      AI->replaceAllUsesWith(InitCall);
82      InitCall->setOperand(1, AI);
83    }
84
85  case 0: break;
86  }
87}
88
89void llvm::IncrementCounterInBlock(BasicBlock *BB, unsigned CounterNum,
90                                   GlobalValue *CounterArray) {
91  // Insert the increment after any alloca or PHI instructions...
92  BasicBlock::iterator InsertPos = BB->begin();
93  while (isa<AllocaInst>(InsertPos) || isa<PHINode>(InsertPos))
94    ++InsertPos;
95
96  // Create the getelementptr constant expression
97  std::vector<Constant*> Indices(2);
98  Indices[0] = Constant::getNullValue(Type::IntTy);
99  Indices[1] = ConstantInt::get(Type::IntTy, CounterNum);
100  Constant *ElementPtr = ConstantExpr::getGetElementPtr(CounterArray, Indices);
101
102  // Load, increment and store the value back.
103  Value *OldVal = new LoadInst(ElementPtr, "OldFuncCounter", InsertPos);
104  Value *NewVal = BinaryOperator::create(Instruction::Add, OldVal,
105                                         ConstantInt::get(Type::UIntTy, 1),
106                                         "NewFuncCounter", InsertPos);
107  new StoreInst(NewVal, ElementPtr, InsertPos);
108}
109