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 "ProfilingUtils.h"
32 class FunctionProfiler : public ModulePass {
33 bool runOnModule(Module &M);
36 RegisterOpt<FunctionProfiler> X("insert-function-profiling",
37 "Insert instrumentation for function profiling");
40 bool FunctionProfiler::runOnModule(Module &M) {
41 Function *Main = M.getMainFunction();
43 std::cerr << "WARNING: cannot insert function profiling into a module"
44 << " with no main function!\n";
45 return false; // No main, no instrumentation!
48 unsigned NumFunctions = 0;
49 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
53 const Type *ATy = ArrayType::get(Type::UIntTy, NumFunctions);
54 GlobalVariable *Counters =
55 new GlobalVariable(ATy, false, GlobalValue::InternalLinkage,
56 Constant::getNullValue(ATy), "FuncProfCounters", &M);
58 // Instrument all of the functions...
60 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
62 // Insert counter at the start of the function
63 IncrementCounterInBlock(I->begin(), i++, Counters);
65 // Add the initialization call to main.
66 InsertProfilingInitCall(Main, "llvm_start_func_profiling", Counters);
72 class BlockProfiler : public ModulePass {
73 bool runOnModule(Module &M);
76 RegisterOpt<BlockProfiler> Y("insert-block-profiling",
77 "Insert instrumentation for block profiling");
80 bool BlockProfiler::runOnModule(Module &M) {
81 Function *Main = M.getMainFunction();
83 std::cerr << "WARNING: cannot insert block profiling into a module"
84 << " with no main function!\n";
85 return false; // No main, no instrumentation!
88 unsigned NumBlocks = 0;
89 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
90 NumBlocks += I->size();
92 const Type *ATy = ArrayType::get(Type::UIntTy, NumBlocks);
93 GlobalVariable *Counters =
94 new GlobalVariable(ATy, false, GlobalValue::InternalLinkage,
95 Constant::getNullValue(ATy), "BlockProfCounters", &M);
97 // Instrument all of the blocks...
99 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
100 for (Function::iterator BB = I->begin(), E = I->end(); BB != E; ++BB)
101 // Insert counter at the start of the block
102 IncrementCounterInBlock(BB, i++, Counters);
104 // Add the initialization call to main.
105 InsertProfilingInitCall(Main, "llvm_start_block_profiling", Counters);