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
InsertProfilingInitCall(Function * MainFn,const char * FnName,GlobalValue * Array,PointerType * arrayType)24 void llvm::InsertProfilingInitCall(Function *MainFn, const char *FnName,
25 GlobalValue *Array,
26 PointerType *arrayType) {
27 LLVMContext &Context = MainFn->getContext();
28 Type *ArgVTy =
29 PointerType::getUnqual(Type::getInt8PtrTy(Context));
30 PointerType *UIntPtr = arrayType ? arrayType :
31 Type::getInt32PtrTy(Context);
32 Module &M = *MainFn->getParent();
33 Constant *InitFn = M.getOrInsertFunction(FnName, Type::getInt32Ty(Context),
34 Type::getInt32Ty(Context),
35 ArgVTy, UIntPtr,
36 Type::getInt32Ty(Context),
37 (Type *)0);
38
39 // This could force argc and argv into programs that wouldn't otherwise have
40 // them, but instead we just pass null values in.
41 std::vector<Value*> Args(4);
42 Args[0] = Constant::getNullValue(Type::getInt32Ty(Context));
43 Args[1] = Constant::getNullValue(ArgVTy);
44
45 // Skip over any allocas in the entry block.
46 BasicBlock *Entry = MainFn->begin();
47 BasicBlock::iterator InsertPos = Entry->begin();
48 while (isa<AllocaInst>(InsertPos)) ++InsertPos;
49
50 std::vector<Constant*> GEPIndices(2,
51 Constant::getNullValue(Type::getInt32Ty(Context)));
52 unsigned NumElements = 0;
53 if (Array) {
54 Args[2] = ConstantExpr::getGetElementPtr(Array, GEPIndices);
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 CallInst *InitCall = CallInst::Create(InitFn, Args, "newargc", InsertPos);
65
66 // If argc or argv are not available in main, just pass null values in.
67 Function::arg_iterator AI;
68 switch (MainFn->arg_size()) {
69 default:
70 case 2:
71 AI = MainFn->arg_begin(); ++AI;
72 if (AI->getType() != ArgVTy) {
73 Instruction::CastOps opcode = CastInst::getCastOpcode(AI, false, ArgVTy,
74 false);
75 InitCall->setArgOperand(1,
76 CastInst::Create(opcode, AI, ArgVTy, "argv.cast", InitCall));
77 } else {
78 InitCall->setArgOperand(1, AI);
79 }
80 /* FALL THROUGH */
81
82 case 1:
83 AI = MainFn->arg_begin();
84 // If the program looked at argc, have it look at the return value of the
85 // init call instead.
86 if (!AI->getType()->isIntegerTy(32)) {
87 Instruction::CastOps opcode;
88 if (!AI->use_empty()) {
89 opcode = CastInst::getCastOpcode(InitCall, true, AI->getType(), true);
90 AI->replaceAllUsesWith(
91 CastInst::Create(opcode, InitCall, AI->getType(), "", InsertPos));
92 }
93 opcode = CastInst::getCastOpcode(AI, true,
94 Type::getInt32Ty(Context), true);
95 InitCall->setArgOperand(0,
96 CastInst::Create(opcode, AI, Type::getInt32Ty(Context),
97 "argc.cast", InitCall));
98 } else {
99 AI->replaceAllUsesWith(InitCall);
100 InitCall->setArgOperand(0, AI);
101 }
102
103 case 0: break;
104 }
105 }
106
IncrementCounterInBlock(BasicBlock * BB,unsigned CounterNum,GlobalValue * CounterArray,bool beginning)107 void llvm::IncrementCounterInBlock(BasicBlock *BB, unsigned CounterNum,
108 GlobalValue *CounterArray, bool beginning) {
109 // Insert the increment after any alloca or PHI instructions...
110 BasicBlock::iterator InsertPos = beginning ? BB->getFirstInsertionPt() :
111 BB->getTerminator();
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);
123
124 // Load, increment and store the value back.
125 Value *OldVal = new LoadInst(ElementPtr, "OldFuncCounter", InsertPos);
126 Value *NewVal = BinaryOperator::Create(Instruction::Add, OldVal,
127 ConstantInt::get(Type::getInt32Ty(Context), 1),
128 "NewFuncCounter", InsertPos);
129 new StoreInst(NewVal, ElementPtr, InsertPos);
130 }
131
InsertProfilingShutdownCall(Function * Callee,Module * Mod)132 void llvm::InsertProfilingShutdownCall(Function *Callee, Module *Mod) {
133 // llvm.global_dtors is an array of type { i32, void ()* }. Prepare those
134 // types.
135 Type *GlobalDtorElems[2] = {
136 Type::getInt32Ty(Mod->getContext()),
137 FunctionType::get(Type::getVoidTy(Mod->getContext()), false)->getPointerTo()
138 };
139 StructType *GlobalDtorElemTy =
140 StructType::get(Mod->getContext(), GlobalDtorElems, false);
141
142 // Construct the new element we'll be adding.
143 Constant *Elem[2] = {
144 ConstantInt::get(Type::getInt32Ty(Mod->getContext()), 65535),
145 ConstantExpr::getBitCast(Callee, GlobalDtorElems[1])
146 };
147
148 // If llvm.global_dtors exists, make a copy of the things in its list and
149 // delete it, to replace it with one that has a larger array type.
150 std::vector<Constant *> dtors;
151 if (GlobalVariable *GlobalDtors = Mod->getNamedGlobal("llvm.global_dtors")) {
152 if (ConstantArray *InitList =
153 dyn_cast<ConstantArray>(GlobalDtors->getInitializer())) {
154 for (unsigned i = 0, e = InitList->getType()->getNumElements();
155 i != e; ++i)
156 dtors.push_back(cast<Constant>(InitList->getOperand(i)));
157 }
158 GlobalDtors->eraseFromParent();
159 }
160
161 // Build up llvm.global_dtors with our new item in it.
162 GlobalVariable *GlobalDtors = new GlobalVariable(
163 *Mod, ArrayType::get(GlobalDtorElemTy, 1), false,
164 GlobalValue::AppendingLinkage, NULL, "llvm.global_dtors");
165
166 dtors.push_back(ConstantStruct::get(GlobalDtorElemTy, Elem));
167 GlobalDtors->setInitializer(ConstantArray::get(
168 cast<ArrayType>(GlobalDtors->getType()->getElementType()), dtors));
169 }
170