1 //===- BlockProfiling.cpp - Insert counters for block profiling -----------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This pass instruments the specified program with counters for basic block or
11 // function profiling. This is the most basic form of profiling, which can tell
12 // which blocks are hot, but cannot reliably detect hot paths through the CFG.
13 // Block profiling counts the number of times each basic block executes, and
14 // function profiling counts the number of times each function is called.
16 // Note that this implementation is very naive. Control equivalent regions of
17 // the CFG should not require duplicate counters, but we do put duplicate
20 //===----------------------------------------------------------------------===//
22 #include "llvm/Constants.h"
23 #include "llvm/DerivedTypes.h"
24 #include "llvm/LLVMContext.h"
25 #include "llvm/Module.h"
26 #include "llvm/Pass.h"
27 #include "llvm/Support/Compiler.h"
28 #include "llvm/Support/Streams.h"
29 #include "llvm/Transforms/Instrumentation.h"
30 #include "RSProfiling.h"
31 #include "ProfilingUtils.h"
35 class VISIBILITY_HIDDEN FunctionProfiler : public RSProfilers_std {
38 bool runOnModule(Module &M);
42 char FunctionProfiler::ID = 0;
44 static RegisterPass<FunctionProfiler>
45 X("insert-function-profiling",
46 "Insert instrumentation for function profiling");
47 static RegisterAnalysisGroup<RSProfilers> XG(X);
49 ModulePass *llvm::createFunctionProfilerPass() {
50 return new FunctionProfiler();
53 bool FunctionProfiler::runOnModule(Module &M) {
54 Function *Main = M.getFunction("main");
56 cerr << "WARNING: cannot insert function profiling into a module"
57 << " with no main function!\n";
58 return false; // No main, no instrumentation!
61 unsigned NumFunctions = 0;
62 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
63 if (!I->isDeclaration())
66 const Type *ATy = ArrayType::get(Type::Int32Ty, NumFunctions);
67 GlobalVariable *Counters =
68 new GlobalVariable(M, ATy, false, GlobalValue::InternalLinkage,
69 Constant::getNullValue(ATy), "FuncProfCounters");
71 // Instrument all of the functions...
73 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
74 if (!I->isDeclaration())
75 // Insert counter at the start of the function
76 IncrementCounterInBlock(&I->getEntryBlock(), i++, Counters);
78 // Add the initialization call to main.
79 InsertProfilingInitCall(Main, "llvm_start_func_profiling", Counters);
85 class BlockProfiler : public RSProfilers_std {
86 bool runOnModule(Module &M);
92 char BlockProfiler::ID = 0;
93 static RegisterPass<BlockProfiler>
94 Y("insert-block-profiling", "Insert instrumentation for block profiling");
95 static RegisterAnalysisGroup<RSProfilers> YG(Y);
97 ModulePass *llvm::createBlockProfilerPass() { return new BlockProfiler(); }
99 bool BlockProfiler::runOnModule(Module &M) {
100 Function *Main = M.getFunction("main");
102 cerr << "WARNING: cannot insert block profiling into a module"
103 << " with no main function!\n";
104 return false; // No main, no instrumentation!
107 unsigned NumBlocks = 0;
108 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
109 if (!I->isDeclaration())
110 NumBlocks += I->size();
112 const Type *ATy = ArrayType::get(Type::Int32Ty, NumBlocks);
113 GlobalVariable *Counters =
114 new GlobalVariable(M, ATy, false, GlobalValue::InternalLinkage,
115 Constant::getNullValue(ATy), "BlockProfCounters");
117 // Instrument all of the blocks...
119 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) {
120 if (I->isDeclaration()) continue;
121 for (Function::iterator BB = I->begin(), E = I->end(); BB != E; ++BB)
122 // Insert counter at the start of the block
123 IncrementCounterInBlock(BB, i++, Counters);
126 // Add the initialization call to main.
127 InsertProfilingInitCall(Main, "llvm_start_block_profiling", Counters);