1 //===- BlockProfiling.cpp - Insert counters for block profiling -----------===//
3 // The LLVM Compiler Infrastructure
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.
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/Module.h"
25 #include "llvm/Pass.h"
26 #include "llvm/Transforms/Instrumentation.h"
27 #include "ProfilingUtils.h"
33 class FunctionProfiler : public ModulePass {
34 bool runOnModule(Module &M);
37 RegisterOpt<FunctionProfiler> X("insert-function-profiling",
38 "Insert instrumentation for function profiling");
41 ModulePass *llvm::createFunctionProfilerPass() {
42 return new FunctionProfiler();
45 bool FunctionProfiler::runOnModule(Module &M) {
46 Function *Main = M.getMainFunction();
48 std::cerr << "WARNING: cannot insert function profiling into a module"
49 << " with no main function!\n";
50 return false; // No main, no instrumentation!
53 unsigned NumFunctions = 0;
54 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
58 const Type *ATy = ArrayType::get(Type::UIntTy, NumFunctions);
59 GlobalVariable *Counters =
60 new GlobalVariable(ATy, false, GlobalValue::InternalLinkage,
61 Constant::getNullValue(ATy), "FuncProfCounters", &M);
63 // Instrument all of the functions...
65 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
67 // Insert counter at the start of the function
68 IncrementCounterInBlock(I->begin(), i++, Counters);
70 // Add the initialization call to main.
71 InsertProfilingInitCall(Main, "llvm_start_func_profiling", Counters);
77 class BlockProfiler : public ModulePass {
78 bool runOnModule(Module &M);
81 RegisterOpt<BlockProfiler> Y("insert-block-profiling",
82 "Insert instrumentation for block profiling");
85 ModulePass *llvm::createBlockProfilerPass() { return new BlockProfiler(); }
87 bool BlockProfiler::runOnModule(Module &M) {
88 Function *Main = M.getMainFunction();
90 std::cerr << "WARNING: cannot insert block profiling into a module"
91 << " with no main function!\n";
92 return false; // No main, no instrumentation!
95 unsigned NumBlocks = 0;
96 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
97 NumBlocks += I->size();
99 const Type *ATy = ArrayType::get(Type::UIntTy, NumBlocks);
100 GlobalVariable *Counters =
101 new GlobalVariable(ATy, false, GlobalValue::InternalLinkage,
102 Constant::getNullValue(ATy), "BlockProfCounters", &M);
104 // Instrument all of the blocks...
106 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
107 for (Function::iterator BB = I->begin(), E = I->end(); BB != E; ++BB)
108 // Insert counter at the start of the block
109 IncrementCounterInBlock(BB, i++, Counters);
111 // Add the initialization call to main.
112 InsertProfilingInitCall(Main, "llvm_start_block_profiling", Counters);