llvm-6502/lib/Transforms/Instrumentation/GCOVProfiling.cpp

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//===- GCOVProfiling.cpp - Insert edge counters for gcov profiling --------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This pass implements GCOV-style profiling. When this pass is run it emits
// "gcno" files next to the existing source, and instruments the code that runs
// to records the edges between blocks that run and emit a complementary "gcda"
// file on exit.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "insert-gcov-profiling"
#include "ProfilingUtils.h"
#include "llvm/Transforms/Instrumentation.h"
#include "llvm/Analysis/DebugInfo.h"
#include "llvm/Module.h"
#include "llvm/Pass.h"
#include "llvm/Instructions.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/DebugLoc.h"
#include "llvm/Support/InstIterator.h"
#include "llvm/Support/IRBuilder.h"
#include "llvm/Support/PathV2.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/UniqueVector.h"
#include <string>
#include <utility>
using namespace llvm;
namespace {
class GCOVProfiler : public ModulePass {
bool runOnModule(Module &M);
public:
static char ID;
GCOVProfiler()
: ModulePass(ID), EmitNotes(true), EmitData(true) {
initializeGCOVProfilerPass(*PassRegistry::getPassRegistry());
}
GCOVProfiler(bool EmitNotes, bool EmitData)
: ModulePass(ID), EmitNotes(EmitNotes), EmitData(EmitData) {
assert((EmitNotes || EmitData) && "GCOVProfiler asked to do nothing?");
initializeGCOVProfilerPass(*PassRegistry::getPassRegistry());
}
virtual const char *getPassName() const {
return "GCOV Profiler";
}
private:
// Create the GCNO files for the Module based on DebugInfo.
void EmitGCNO(DebugInfoFinder &DIF);
// Modify the program to track transitions along edges and call into the
// profiling runtime to emit .gcda files when run.
bool EmitProfileArcs(DebugInfoFinder &DIF);
// Get pointers to the functions in the runtime library.
Constant *getStartFileFunc();
Constant *getEmitFunctionFunc();
Constant *getEmitArcsFunc();
Constant *getEndFileFunc();
// Add the function to write out all our counters to the global destructor
// list.
void InsertCounterWriteout(DebugInfoFinder &,
SmallVector<std::pair<GlobalVariable *,
uint32_t>, 8> &);
bool EmitNotes;
bool EmitData;
Module *Mod;
LLVMContext *Ctx;
};
}
char GCOVProfiler::ID = 0;
INITIALIZE_PASS(GCOVProfiler, "insert-gcov-profiling",
"Insert instrumentation for GCOV profiling", false, false)
ModulePass *llvm::createGCOVProfilerPass(bool EmitNotes, bool EmitData) {
return new GCOVProfiler(EmitNotes, EmitData);
}
static DISubprogram FindSubprogram(DIScope scope) {
while (!scope.isSubprogram()) {
assert(scope.isLexicalBlock() &&
"Debug location not lexical block or subprogram");
scope = DILexicalBlock(scope).getContext();
}
return DISubprogram(scope);
}
namespace {
class GCOVRecord {
protected:
static const char *lines_tag;
static const char *function_tag;
static const char *block_tag;
static const char *edge_tag;
GCOVRecord() {}
void WriteBytes(const char *b, int size) {
os->write(b, size);
}
void Write(uint32_t i) {
WriteBytes(reinterpret_cast<char*>(&i), 4);
}
// Returns the length measured in 4-byte blocks that will be used to
// represent this string in a GCOV file
unsigned LengthOfGCOVString(StringRef s) {
// A GCOV string is a length, followed by a NUL, then between 0 and 3 NULs
// padding out to the next 4-byte word. The length is measured in 4-byte
// words including padding, not bytes of actual string.
return (s.size() + 5) / 4;
}
void WriteGCOVString(StringRef s) {
uint32_t len = LengthOfGCOVString(s);
Write(len);
WriteBytes(s.data(), s.size());
// Write 1 to 4 bytes of NUL padding.
assert((unsigned)(5 - ((s.size() + 1) % 4)) > 0);
assert((unsigned)(5 - ((s.size() + 1) % 4)) <= 4);
WriteBytes("\0\0\0\0", 5 - ((s.size() + 1) % 4));
}
raw_ostream *os;
};
const char *GCOVRecord::lines_tag = "\0\0\x45\x01";
const char *GCOVRecord::function_tag = "\0\0\0\1";
const char *GCOVRecord::block_tag = "\0\0\x41\x01";
const char *GCOVRecord::edge_tag = "\0\0\x43\x01";
class GCOVFunction;
class GCOVBlock;
// Constructed only by requesting it from a GCOVBlock, this object stores a
// list of line numbers and a single filename, representing lines that belong
// to the block.
class GCOVLines : public GCOVRecord {
public:
void AddLine(uint32_t line) {
lines.push_back(line);
}
uint32_t Length() {
return LengthOfGCOVString(filename) + 2 + lines.size();
}
private:
friend class GCOVBlock;
GCOVLines(std::string filename, raw_ostream *os)
: filename(filename) {
this->os = os;
}
std::string filename;
SmallVector<uint32_t, 32> lines;
};
// Represent a basic block in GCOV. Each block has a unique number in the
// function, number of lines belonging to each block, and a set of edges to
// other blocks.
class GCOVBlock : public GCOVRecord {
public:
GCOVLines &GetFile(std::string filename) {
GCOVLines *&lines = lines_by_file[filename];
if (!lines) {
lines = new GCOVLines(filename, os);
}
return *lines;
}
void AddEdge(GCOVBlock &successor) {
out_edges.push_back(&successor);
}
void WriteOut() {
uint32_t len = 3;
for (StringMap<GCOVLines *>::iterator I = lines_by_file.begin(),
E = lines_by_file.end(); I != E; ++I) {
len += I->second->Length();
}
WriteBytes(lines_tag, 4);
Write(len);
Write(number);
for (StringMap<GCOVLines *>::iterator I = lines_by_file.begin(),
E = lines_by_file.end(); I != E; ++I) {
Write(0);
WriteGCOVString(I->second->filename);
for (int i = 0, e = I->second->lines.size(); i != e; ++i) {
Write(I->second->lines[i]);
}
}
Write(0);
Write(0);
}
~GCOVBlock() {
DeleteContainerSeconds(lines_by_file);
}
private:
friend class GCOVFunction;
GCOVBlock(uint32_t number, raw_ostream *os)
: number(number) {
this->os = os;
}
uint32_t number;
BasicBlock *block;
StringMap<GCOVLines *> lines_by_file;
SmallVector<GCOVBlock *, 4> out_edges;
};
// A function has a unique identifier, a checksum (we leave as zero) and a
// set of blocks and a map of edges between blocks. This is the only GCOV
// object users can construct, the blocks and lines will be rooted here.
class GCOVFunction : public GCOVRecord {
public:
GCOVFunction(DISubprogram SP, raw_ostream *os) {
this->os = os;
Function *F = SP.getFunction();
uint32_t i = 0;
for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
blocks[BB] = new GCOVBlock(i++, os);
}
return_block = new GCOVBlock(i++, os);
WriteBytes(function_tag, 4);
uint32_t block_len = 1 + 1 + 1 + LengthOfGCOVString(SP.getName()) +
1 + LengthOfGCOVString(SP.getFilename()) + 1;
Write(block_len);
uint32_t ident = reinterpret_cast<intptr_t>((MDNode*)SP);
Write(ident);
Write(0); // checksum
WriteGCOVString(SP.getName());
WriteGCOVString(SP.getFilename());
Write(SP.getLineNumber());
}
~GCOVFunction() {
DeleteContainerSeconds(blocks);
delete return_block;
}
GCOVBlock &GetBlock(BasicBlock *BB) {
return *blocks[BB];
}
GCOVBlock &GetReturnBlock() {
return *return_block;
}
void WriteOut() {
// Emit count of blocks.
WriteBytes(block_tag, 4);
Write(blocks.size() + 1);
for (int i = 0, e = blocks.size() + 1; i != e; ++i) {
Write(0); // No flags on our blocks.
}
// Emit edges between blocks.
for (DenseMap<BasicBlock *, GCOVBlock *>::iterator I = blocks.begin(),
E = blocks.end(); I != E; ++I) {
GCOVBlock &block = *I->second;
if (block.out_edges.empty()) continue;
WriteBytes(edge_tag, 4);
Write(block.out_edges.size() * 2 + 1);
Write(block.number);
for (int i = 0, e = block.out_edges.size(); i != e; ++i) {
Write(block.out_edges[i]->number);
Write(0); // no flags
}
}
// Emit lines for each block.
for (DenseMap<BasicBlock *, GCOVBlock *>::iterator I = blocks.begin(),
E = blocks.end(); I != E; ++I) {
I->second->WriteOut();
}
}
private:
DenseMap<BasicBlock *, GCOVBlock *> blocks;
GCOVBlock *return_block;
};
}
// Replace the stem of a file, or add one if missing.
static std::string ReplaceStem(std::string orig_filename, std::string new_stem){
return (sys::path::stem(orig_filename) + "." + new_stem).str();
}
bool GCOVProfiler::runOnModule(Module &M) {
Mod = &M;
Ctx = &M.getContext();
DebugInfoFinder DIF;
DIF.processModule(*Mod);
if (EmitNotes) EmitGCNO(DIF);
if (EmitData) return EmitProfileArcs(DIF);
return false;
}
void GCOVProfiler::EmitGCNO(DebugInfoFinder &DIF) {
DenseMap<const MDNode *, raw_fd_ostream *> gcno_files;
for (DebugInfoFinder::iterator I = DIF.compile_unit_begin(),
E = DIF.compile_unit_end(); I != E; ++I) {
// Each compile unit gets its own .gcno file. This means that whether we run
// this pass over the original .o's as they're produced, or run it after
// LTO, we'll generate the same .gcno files.
DICompileUnit CU(*I);
raw_fd_ostream *&Out = gcno_files[CU];
std::string ErrorInfo;
Out = new raw_fd_ostream(ReplaceStem(CU.getFilename(), "gcno").c_str(),
ErrorInfo, raw_fd_ostream::F_Binary);
Out->write("oncg*404MVLL", 12);
}
for (DebugInfoFinder::iterator SPI = DIF.subprogram_begin(),
SPE = DIF.subprogram_end(); SPI != SPE; ++SPI) {
DISubprogram SP(*SPI);
raw_fd_ostream *&os = gcno_files[SP.getCompileUnit()];
GCOVFunction function(SP, os);
Function *F = SP.getFunction();
for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
GCOVBlock &block = function.GetBlock(BB);
TerminatorInst *TI = BB->getTerminator();
if (int successors = TI->getNumSuccessors()) {
for (int i = 0; i != successors; ++i) {
block.AddEdge(function.GetBlock(TI->getSuccessor(i)));
}
} else if (isa<ReturnInst>(TI)) {
block.AddEdge(function.GetReturnBlock());
}
uint32_t line = 0;
for (BasicBlock::iterator I = BB->begin(), IE = BB->end(); I != IE; ++I) {
const DebugLoc &loc = I->getDebugLoc();
if (loc.isUnknown()) continue;
if (line == loc.getLine()) continue;
line = loc.getLine();
if (SP != FindSubprogram(DIScope(loc.getScope(*Ctx)))) continue;
GCOVLines &lines = block.GetFile(SP.getFilename());
lines.AddLine(loc.getLine());
}
}
function.WriteOut();
}
for (DenseMap<const MDNode *, raw_fd_ostream *>::iterator
I = gcno_files.begin(), E = gcno_files.end(); I != E; ++I) {
raw_fd_ostream *&Out = I->second;
Out->write("\0\0\0\0\0\0\0\0", 8); // EOF
Out->close();
delete Out;
}
}
bool GCOVProfiler::EmitProfileArcs(DebugInfoFinder &DIF) {
if (DIF.subprogram_begin() == DIF.subprogram_end())
return false;
SmallVector<std::pair<GlobalVariable *, uint32_t>, 8> counters_by_ident;
for (DebugInfoFinder::iterator SPI = DIF.subprogram_begin(),
SPE = DIF.subprogram_end(); SPI != SPE; ++SPI) {
DISubprogram SP(*SPI);
Function *F = SP.getFunction();
unsigned edges = 0;
for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
TerminatorInst *TI = BB->getTerminator();
if (isa<ReturnInst>(TI))
++edges;
else
edges += TI->getNumSuccessors();
}
const ArrayType *counter_type =
ArrayType::get(Type::getInt64Ty(*Ctx), edges);
GlobalVariable *counter =
new GlobalVariable(*Mod, counter_type, false,
GlobalValue::InternalLinkage,
Constant::getNullValue(counter_type),
"__llvm_gcov_ctr", 0, false, 0);
counters_by_ident.push_back(
std::make_pair(counter, reinterpret_cast<intptr_t>((MDNode*)SP)));
UniqueVector<BasicBlock *> complex_edge_preds;
UniqueVector<BasicBlock *> complex_edge_succs;
unsigned edge_num = 0;
for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
TerminatorInst *TI = BB->getTerminator();
int successors = isa<ReturnInst>(TI) ? 1 : TI->getNumSuccessors();
if (successors) {
IRBuilder<> builder(TI);
if (successors == 1) {
Value *ctr = builder.CreateConstInBoundsGEP2_64(counter, 0, edge_num);
Value *count = builder.CreateLoad(ctr);
count = builder.CreateAdd(count,
ConstantInt::get(Type::getInt64Ty(*Ctx),1));
builder.CreateStore(count, ctr);
} else if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
Value *sel = builder.CreateSelect(
BI->getCondition(),
ConstantInt::get(Type::getInt64Ty(*Ctx), edge_num),
ConstantInt::get(Type::getInt64Ty(*Ctx), edge_num + 1));
SmallVector<Value *, 2> idx;
idx.push_back(Constant::getNullValue(Type::getInt64Ty(*Ctx)));
idx.push_back(sel);
Value *ctr = builder.CreateInBoundsGEP(counter,
idx.begin(), idx.end());
Value *count = builder.CreateLoad(ctr);
count = builder.CreateAdd(count,
ConstantInt::get(Type::getInt64Ty(*Ctx),1));
builder.CreateStore(count, ctr);
} else {
complex_edge_preds.insert(BB);
for (int i = 0; i != successors; ++i) {
complex_edge_succs.insert(TI->getSuccessor(i));
}
}
edge_num += successors;
}
}
// TODO: support switch, invoke, indirectbr
if (!complex_edge_preds.empty()) {
// emit a [preds x [succs x i64*]].
for (int i = 0, e = complex_edge_preds.size(); i != e; ++i) {
// call runtime to state save
}
for (int i = 0, e = complex_edge_succs.size(); i != e; ++i) {
// call runtime to perform increment
}
}
}
InsertCounterWriteout(DIF, counters_by_ident);
return true;
}
Constant *GCOVProfiler::getStartFileFunc() {
const Type *Args[1] = { Type::getInt8PtrTy(*Ctx) };
const FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx),
Args, false);
return Mod->getOrInsertFunction("llvm_gcda_start_file", FTy);
}
Constant *GCOVProfiler::getEmitFunctionFunc() {
const Type *Args[1] = { Type::getInt32Ty(*Ctx) };
const FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx),
Args, false);
return Mod->getOrInsertFunction("llvm_gcda_emit_function", FTy);
}
Constant *GCOVProfiler::getEmitArcsFunc() {
const Type *Args[] = {
Type::getInt32Ty(*Ctx), // uint32_t num_counters
Type::getInt64PtrTy(*Ctx), // uint64_t *counters
};
const FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx),
Args, false);
return Mod->getOrInsertFunction("llvm_gcda_emit_arcs", FTy);
}
Constant *GCOVProfiler::getEndFileFunc() {
const FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), false);
return Mod->getOrInsertFunction("llvm_gcda_end_file", FTy);
}
void GCOVProfiler::InsertCounterWriteout(
DebugInfoFinder &DIF,
SmallVector<std::pair<GlobalVariable *, uint32_t>, 8> &counters_by_ident) {
const FunctionType *WriteoutFTy =
FunctionType::get(Type::getVoidTy(*Ctx), false);
Function *WriteoutF = Function::Create(WriteoutFTy,
GlobalValue::InternalLinkage,
"__llvm_gcda_writeout", Mod);
WriteoutF->setUnnamedAddr(true);
BasicBlock *BB = BasicBlock::Create(*Ctx, "", WriteoutF);
IRBuilder<> builder(BB);
Constant *StartFile = getStartFileFunc();
Constant *EmitFunction = getEmitFunctionFunc();
Constant *EmitArcs = getEmitArcsFunc();
Constant *EndFile = getEndFileFunc();
for (DebugInfoFinder::iterator CUI = DIF.compile_unit_begin(),
CUE = DIF.compile_unit_end(); CUI != CUE; ++CUI) {
DICompileUnit compile_unit(*CUI);
std::string filename_gcda = ReplaceStem(compile_unit.getFilename(), "gcda");
builder.CreateCall(StartFile,
builder.CreateGlobalStringPtr(filename_gcda));
for (SmallVector<std::pair<GlobalVariable *, uint32_t>, 8>::iterator
I = counters_by_ident.begin(), E = counters_by_ident.end();
I != E; ++I) {
builder.CreateCall(EmitFunction, ConstantInt::get(Type::getInt32Ty(*Ctx),
I->second));
GlobalVariable *GV = I->first;
unsigned num_arcs =
cast<ArrayType>(GV->getType()->getElementType())->getNumElements();
builder.CreateCall2(
EmitArcs,
ConstantInt::get(Type::getInt32Ty(*Ctx), num_arcs),
builder.CreateConstGEP2_64(GV, 0, 0));
}
builder.CreateCall(EndFile);
}
builder.CreateRetVoid();
InsertProfilingShutdownCall(WriteoutF, Mod);
}