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//===- BlockProfiling.cpp - Insert counters for block profiling -----------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This pass instruments the specified program with counters for basic block or
// function profiling. This is the most basic form of profiling, which can tell
// which blocks are hot, but cannot reliably detect hot paths through the CFG.
// Block profiling counts the number of times each basic block executes, and
// function profiling counts the number of times each function is called.
//
// Note that this implementation is very naive. Control equivalent regions of
// the CFG should not require duplicate counters, but we do put duplicate
// counters in.
//
//===----------------------------------------------------------------------===//
#include "llvm/DerivedTypes.h"
#include "llvm/Module.h"
#include "llvm/Pass.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/Instrumentation.h"
#include "RSProfiling.h"
#include "ProfilingUtils.h"
using namespace llvm;
namespace {
class FunctionProfiler : public RSProfilers_std {
public:
static char ID;
bool runOnModule(Module &M);
};
}
char FunctionProfiler::ID = 0;
static RegisterPass<FunctionProfiler>
X("insert-function-profiling",
"Insert instrumentation for function profiling");
static RegisterAnalysisGroup<RSProfilers> XG(X);
ModulePass *llvm::createFunctionProfilerPass() {
return new FunctionProfiler();
}
bool FunctionProfiler::runOnModule(Module &M) {
Function *Main = M.getFunction("main");
if (Main == 0) {
errs() << "WARNING: cannot insert function profiling into a module"
<< " with no main function!\n";
return false; // No main, no instrumentation!
}
unsigned NumFunctions = 0;
for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
if (!I->isDeclaration())
++NumFunctions;
const Type *ATy = ArrayType::get(Type::getInt32Ty(M.getContext()),
NumFunctions);
GlobalVariable *Counters =
new GlobalVariable(M, ATy, false, GlobalValue::InternalLinkage,
Constant::getNullValue(ATy), "FuncProfCounters");
// Instrument all of the functions...
unsigned i = 0;
for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
if (!I->isDeclaration())
// Insert counter at the start of the function
IncrementCounterInBlock(&I->getEntryBlock(), i++, Counters);
// Add the initialization call to main.
InsertProfilingInitCall(Main, "llvm_start_func_profiling", Counters);
return true;
}
namespace {
class BlockProfiler : public RSProfilers_std {
bool runOnModule(Module &M);
public:
static char ID;
};
}
char BlockProfiler::ID = 0;
static RegisterPass<BlockProfiler>
Y("insert-block-profiling", "Insert instrumentation for block profiling");
static RegisterAnalysisGroup<RSProfilers> YG(Y);
ModulePass *llvm::createBlockProfilerPass() { return new BlockProfiler(); }
bool BlockProfiler::runOnModule(Module &M) {
Function *Main = M.getFunction("main");
if (Main == 0) {
errs() << "WARNING: cannot insert block profiling into a module"
<< " with no main function!\n";
return false; // No main, no instrumentation!
}
unsigned NumBlocks = 0;
for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
if (!I->isDeclaration())
NumBlocks += I->size();
const Type *ATy = ArrayType::get(Type::getInt32Ty(M.getContext()), NumBlocks);
GlobalVariable *Counters =
new GlobalVariable(M, ATy, false, GlobalValue::InternalLinkage,
Constant::getNullValue(ATy), "BlockProfCounters");
// Instrument all of the blocks...
unsigned i = 0;
for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) {
if (I->isDeclaration()) continue;
for (Function::iterator BB = I->begin(), E = I->end(); BB != E; ++BB)
// Insert counter at the start of the block
IncrementCounterInBlock(BB, i++, Counters);
}
// Add the initialization call to main.
InsertProfilingInitCall(Main, "llvm_start_block_profiling", Counters);
return true;
}
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