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