ProfilingUtils.cpp revision 52eec548206d0b135b55ba52dd0e82e978f15ae5 
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::Int8Ty));
26  const PointerType *UIntPtr = PointerType::get(Type::Int32Ty);
27  Module &M = *MainFn->getParent();
28  Constant *InitFn = M.getOrInsertFunction(FnName, Type::Int32Ty, Type::Int32Ty,
29                                           ArgVTy, UIntPtr, Type::Int32Ty,
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::Int32Ty);
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::Int32Ty));
44  unsigned NumElements = 0;
45  if (Array) {
46    Args[2] = ConstantExpr::getGetElementPtr(Array, &GEPIndices[0],
47                                             GEPIndices.size());
48    NumElements =
49      cast<ArrayType>(Array->getType()->getElementType())->getNumElements();
50  } else {
51    // If this profiling instrumentation doesn't have a constant array, just
52    // pass null.
53    Args[2] = ConstantPointerNull::get(UIntPtr);
54  }
55  Args[3] = ConstantInt::get(Type::Int32Ty, NumElements);
56
57  Instruction *InitCall = new CallInst(InitFn, Args.begin(), Args.end(),
58                                       "newargc", InsertPos);
59
60  // If argc or argv are not available in main, just pass null values in.
61  Function::arg_iterator AI;
62  switch (MainFn->arg_size()) {
63  default:
64  case 2:
65    AI = MainFn->arg_begin(); ++AI;
66    if (AI->getType() != ArgVTy) {
67      Instruction::CastOps opcode = CastInst::getCastOpcode(AI, false, ArgVTy,
68                                                            false);
69      InitCall->setOperand(2,
70          CastInst::create(opcode, AI, ArgVTy, "argv.cast", InitCall));
71    } else {
72      InitCall->setOperand(2, AI);
73    }
74    /* FALL THROUGH */
75
76  case 1:
77    AI = MainFn->arg_begin();
78    // If the program looked at argc, have it look at the return value of the
79    // init call instead.
80    if (AI->getType() != Type::Int32Ty) {
81      Instruction::CastOps opcode;
82      if (!AI->use_empty()) {
83        opcode = CastInst::getCastOpcode(InitCall, true, AI->getType(), true);
84        AI->replaceAllUsesWith(
85          CastInst::create(opcode, InitCall, AI->getType(), "", InsertPos));
86      }
87      opcode = CastInst::getCastOpcode(AI, true, Type::Int32Ty, true);
88      InitCall->setOperand(1,
89          CastInst::create(opcode, AI, Type::Int32Ty, "argc.cast", InitCall));
90    } else {
91      AI->replaceAllUsesWith(InitCall);
92      InitCall->setOperand(1, AI);
93    }
94
95  case 0: break;
96  }
97}
98
99void llvm::IncrementCounterInBlock(BasicBlock *BB, unsigned CounterNum,
100                                   GlobalValue *CounterArray) {
101  // Insert the increment after any alloca or PHI instructions...
102  BasicBlock::iterator InsertPos = BB->begin();
103  while (isa<AllocaInst>(InsertPos) || isa<PHINode>(InsertPos))
104    ++InsertPos;
105
106  // Create the getelementptr constant expression
107  std::vector<Constant*> Indices(2);
108  Indices[0] = Constant::getNullValue(Type::Int32Ty);
109  Indices[1] = ConstantInt::get(Type::Int32Ty, CounterNum);
110  Constant *ElementPtr =
111    ConstantExpr::getGetElementPtr(CounterArray, &Indices[0], Indices.size());
112
113  // Load, increment and store the value back.
114  Value *OldVal = new LoadInst(ElementPtr, "OldFuncCounter", InsertPos);
115  Value *NewVal = BinaryOperator::create(Instruction::Add, OldVal,
116                                         ConstantInt::get(Type::Int32Ty, 1),
117                                         "NewFuncCounter", InsertPos);
118  new StoreInst(NewVal, ElementPtr, InsertPos);
119}
120