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::getInt32Ty(M.getContext()),
68 GlobalVariable *Counters =
69 new GlobalVariable(M, ATy, false, GlobalValue::InternalLinkage,
70 Constant::getNullValue(ATy), "FuncProfCounters");
72 // Instrument all of the functions...
74 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
75 if (!I->isDeclaration())
76 // Insert counter at the start of the function
77 IncrementCounterInBlock(&I->getEntryBlock(), i++, Counters);
79 // Add the initialization call to main.
80 InsertProfilingInitCall(Main, "llvm_start_func_profiling", Counters);
86 class BlockProfiler : public RSProfilers_std {
87 bool runOnModule(Module &M);
93 char BlockProfiler::ID = 0;
94 static RegisterPass<BlockProfiler>
95 Y("insert-block-profiling", "Insert instrumentation for block profiling");
96 static RegisterAnalysisGroup<RSProfilers> YG(Y);
98 ModulePass *llvm::createBlockProfilerPass() { return new BlockProfiler(); }
100 bool BlockProfiler::runOnModule(Module &M) {
101 Function *Main = M.getFunction("main");
103 cerr << "WARNING: cannot insert block profiling into a module"
104 << " with no main function!\n";
105 return false; // No main, no instrumentation!
108 unsigned NumBlocks = 0;
109 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
110 if (!I->isDeclaration())
111 NumBlocks += I->size();
113 const Type *ATy = ArrayType::get(Type::getInt32Ty(M.getContext()), NumBlocks);
114 GlobalVariable *Counters =
115 new GlobalVariable(M, ATy, false, GlobalValue::InternalLinkage,
116 Constant::getNullValue(ATy), "BlockProfCounters");
118 // Instrument all of the blocks...
120 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) {
121 if (I->isDeclaration()) continue;
122 for (Function::iterator BB = I->begin(), E = I->end(); BB != E; ++BB)
123 // Insert counter at the start of the block
124 IncrementCounterInBlock(BB, i++, Counters);
127 // Add the initialization call to main.
128 InsertProfilingInitCall(Main, "llvm_start_block_profiling", Counters);