lib/Transforms/Instrumentation/ProfilingUtils.cpp

   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
  24 void llvm::InsertProfilingInitCall(Function *MainFn, const char *FnName,
  25                                    GlobalValue *Array) {
  26   LLVMContext &Context = MainFn->getContext();
  27   const Type *ArgVTy =
  28     PointerType::getUnqual(PointerType::getUnqual(Type::getInt8Ty(Context)));
  29   const PointerType *UIntPtr =
  30         PointerType::getUnqual(Type::getInt32Ty(Context));
  31   Module &M = *MainFn->getParent();
  32   Constant *InitFn = M.getOrInsertFunction(FnName, Type::getInt32Ty(Context),
  33                                            Type::getInt32Ty(Context),
  34                                            ArgVTy, UIntPtr,
  35                                            Type::getInt32Ty(Context),
  36                                            (Type *)0);
  37
  38   // This could force argc and argv into programs that wouldn't otherwise have
  39   // them, but instead we just pass null values in.
  40   std::vector<Value*> Args(4);
  41   Args[0] = Constant::getNullValue(Type::getInt32Ty(Context));
  42   Args[1] = Constant::getNullValue(ArgVTy);
  43
  44   // Skip over any allocas in the entry block.
  45   BasicBlock *Entry = MainFn->begin();
  46   BasicBlock::iterator InsertPos = Entry->begin();
  47   while (isa<AllocaInst>(InsertPos)) ++InsertPos;
  48
  49   std::vector<Constant*> GEPIndices(2,
  50                              Constant::getNullValue(Type::getInt32Ty(Context)));
  51   unsigned NumElements = 0;
  52   if (Array) {
  53     Args[2] = ConstantExpr::getGetElementPtr(Array, &GEPIndices[0],
  54                                              GEPIndices.size());
  55     NumElements =
  56       cast<ArrayType>(Array->getType()->getElementType())->getNumElements();
  57   } else {
  58     // If this profiling instrumentation doesn't have a constant array, just
  59     // pass null.
  60     Args[2] = ConstantPointerNull::get(UIntPtr);
  61   }
  62   Args[3] = ConstantInt::get(Type::getInt32Ty(Context), NumElements);
  63
  64   Instruction *InitCall = CallInst::Create(InitFn, Args.begin(), Args.end(),
  65                                            "newargc", InsertPos);
  66
  67   // If argc or argv are not available in main, just pass null values in.
  68   Function::arg_iterator AI;
  69   switch (MainFn->arg_size()) {
  70   default:
  71   case 2:
  72     AI = MainFn->arg_begin(); ++AI;
  73     if (AI->getType() != ArgVTy) {
  74       Instruction::CastOps opcode = CastInst::getCastOpcode(AI, false, ArgVTy,
  75                                                             false);
  76       InitCall->setOperand(2,
  77           CastInst::Create(opcode, AI, ArgVTy, "argv.cast", InitCall));
  78     } else {
  79       InitCall->setOperand(2, AI);
  80     }
  81     /* FALL THROUGH */
  82
  83   case 1:
  84     AI = MainFn->arg_begin();
  85     // If the program looked at argc, have it look at the return value of the
  86     // init call instead.
  87     if (AI->getType() != Type::getInt32Ty(Context)) {
  88       Instruction::CastOps opcode;
  89       if (!AI->use_empty()) {
  90         opcode = CastInst::getCastOpcode(InitCall, true, AI->getType(), true);
  91         AI->replaceAllUsesWith(
  92           CastInst::Create(opcode, InitCall, AI->getType(), "", InsertPos));
  93       }
  94       opcode = CastInst::getCastOpcode(AI, true,
  95                                        Type::getInt32Ty(Context), true);
  96       InitCall->setOperand(1,
  97           CastInst::Create(opcode, AI, Type::getInt32Ty(Context),
  98                            "argc.cast", InitCall));
  99     } else {
 100       AI->replaceAllUsesWith(InitCall);
 101       InitCall->setOperand(1, AI);
 102     }
 103
 104   case 0: break;
 105   }
 106 }
 107
 108 void llvm::IncrementCounterInBlock(BasicBlock *BB, unsigned CounterNum,
 109                                    GlobalValue *CounterArray) {
 110   // Insert the increment after any alloca or PHI instructions...
 111   BasicBlock::iterator InsertPos = BB->getFirstNonPHI();
 112   while (isa<AllocaInst>(InsertPos))
 113     ++InsertPos;
 114
 115   LLVMContext &Context = BB->getContext();
 116
 117   // Create the getelementptr constant expression
 118   std::vector<Constant*> Indices(2);
 119   Indices[0] = Constant::getNullValue(Type::getInt32Ty(Context));
 120   Indices[1] = ConstantInt::get(Type::getInt32Ty(Context), CounterNum);
 121   Constant *ElementPtr =
 122     ConstantExpr::getGetElementPtr(CounterArray, &Indices[0],
 123                                           Indices.size());
 124
 125   // Load, increment and store the value back.
 126   Value *OldVal = new LoadInst(ElementPtr, "OldFuncCounter", InsertPos);
 127   Value *NewVal = BinaryOperator::Create(Instruction::Add, OldVal,
 128                                  ConstantInt::get(Type::getInt32Ty(Context), 1),
 129                                          "NewFuncCounter", InsertPos);
 130   new StoreInst(NewVal, ElementPtr, InsertPos);
 131 }