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llvm-6502/lib/Transforms/Instrumentation/GCOVProfiling.cpp
Nick Lewycky 7a2ba2fbe4 Only read *predecessor once so as to fix a theoretical issue where it changes 
between two reads (threading).

Fix an off-by-one in the indirect counter table that I meant to revert after an
earlier experiment. Whoops!

Implement GCOV_PREFIX. Doesn't handle GCOV_PREFIX_STRIP yet.

Fix an off-by-one in string emission. Extra whoops!

Tolerate DISubprograms that have null Function*'s attached to them. I don't yet
understand what this means, but it happens when you have a global static with
a non-trivial constructor/destructor.

Fix a crash on switch statements with a single successor (default-only).


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130443 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-28 21:35:49 +00:00

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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 *getIncrementIndirectCounterFunc();
Constant *getEmitFunctionFunc();
Constant *getEmitArcsFunc();
Constant *getEndFileFunc();
// Create or retrieve an i32 state value that is used to represent the
// pred block number for certain non-trivial edges.
GlobalVariable *getEdgeStateValue();
// Produce a table of pointers to counters, by predecessor and successor
// block number.
GlobalVariable *buildEdgeLookupTable(Function *F,
GlobalVariable *Counter,
const UniqueVector<BasicBlock *> &Preds,
const UniqueVector<BasicBlock *> &Succs);
// 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 *M;
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 *LinesTag;
static const char *FunctionTag;
static const char *BlockTag;
static const char *EdgeTag;
GCOVRecord() {}
void writeBytes(const char *Bytes, int Size) {
os->write(Bytes, 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)(4 - (s.size() % 4)) > 0);
assert((unsigned)(4 - (s.size() % 4)) <= 4);
writeBytes("\0\0\0\0", 4 - (s.size() % 4));
}
raw_ostream *os;
};
const char *GCOVRecord::LinesTag = "\0\0\x45\x01";
const char *GCOVRecord::FunctionTag = "\0\0\0\1";
const char *GCOVRecord::BlockTag = "\0\0\x41\x01";
const char *GCOVRecord::EdgeTag = "\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 = LinesByFile[Filename];
if (!Lines) {
Lines = new GCOVLines(Filename, os);
}
return *Lines;
}
void addEdge(GCOVBlock &Successor) {
OutEdges.push_back(&Successor);
}
void writeOut() {
uint32_t Len = 3;
for (StringMap<GCOVLines *>::iterator I = LinesByFile.begin(),
E = LinesByFile.end(); I != E; ++I) {
Len += I->second->length();
}
writeBytes(LinesTag, 4);
write(Len);
write(Number);
for (StringMap<GCOVLines *>::iterator I = LinesByFile.begin(),
E = LinesByFile.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(LinesByFile);
}
private:
friend class GCOVFunction;
GCOVBlock(uint32_t Number, raw_ostream *os)
: Number(Number) {
this->os = os;
}
uint32_t Number;
StringMap<GCOVLines *> LinesByFile;
SmallVector<GCOVBlock *, 4> OutEdges;
};
// 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);
}
ReturnBlock = new GCOVBlock(i++, os);
writeBytes(FunctionTag, 4);
uint32_t BlockLen = 1 + 1 + 1 + lengthOfGCOVString(SP.getName()) +
1 + lengthOfGCOVString(SP.getFilename()) + 1;
write(BlockLen);
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 ReturnBlock;
}
GCOVBlock &getBlock(BasicBlock *BB) {
return *Blocks[BB];
}
GCOVBlock &getReturnBlock() {
return *ReturnBlock;
}
void writeOut() {
// Emit count of blocks.
writeBytes(BlockTag, 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.OutEdges.empty()) continue;
writeBytes(EdgeTag, 4);
write(Block.OutEdges.size() * 2 + 1);
write(Block.Number);
for (int i = 0, e = Block.OutEdges.size(); i != e; ++i) {
write(Block.OutEdges[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 *ReturnBlock;
};
}
// Replace the stem of a file, or add one if missing.
static std::string replaceStem(std::string OrigFilename, std::string NewStem) {
return (sys::path::stem(OrigFilename) + "." + NewStem).str();
}
bool GCOVProfiler::runOnModule(Module &M) {
this->M = &M;
Ctx = &M.getContext();
DebugInfoFinder DIF;
DIF.processModule(M);
if (EmitNotes) emitGCNO(DIF);
if (EmitData) return emitProfileArcs(DIF);
return false;
}
void GCOVProfiler::emitGCNO(DebugInfoFinder &DIF) {
DenseMap<const MDNode *, raw_fd_ostream *> GcnoFiles;
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 = GcnoFiles[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 = GcnoFiles[SP.getCompileUnit()];
Function *F = SP.getFunction();
if (!F) continue;
GCOVFunction Func(SP, os);
for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
GCOVBlock &Block = Func.getBlock(BB);
TerminatorInst *TI = BB->getTerminator();
if (int successors = TI->getNumSuccessors()) {
for (int i = 0; i != successors; ++i) {
Block.addEdge(Func.getBlock(TI->getSuccessor(i)));
}
} else if (isa<ReturnInst>(TI)) {
Block.addEdge(Func.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());
}
}
Func.writeOut();
}
for (DenseMap<const MDNode *, raw_fd_ostream *>::iterator
I = GcnoFiles.begin(), E = GcnoFiles.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> CountersByIdent;
for (DebugInfoFinder::iterator SPI = DIF.subprogram_begin(),
SPE = DIF.subprogram_end(); SPI != SPE; ++SPI) {
DISubprogram SP(*SPI);
Function *F = SP.getFunction();
if (!F) continue;
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 *CounterTy =
ArrayType::get(Type::getInt64Ty(*Ctx), Edges);
GlobalVariable *Counters =
new GlobalVariable(*M, CounterTy, false,
GlobalValue::InternalLinkage,
Constant::getNullValue(CounterTy),
"__llvm_gcov_ctr", 0, false, 0);
CountersByIdent.push_back(
std::make_pair(Counters, reinterpret_cast<intptr_t>((MDNode*)SP)));
UniqueVector<BasicBlock *> ComplexEdgePreds;
UniqueVector<BasicBlock *> ComplexEdgeSuccs;
unsigned Edge = 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 *Counter = Builder.CreateConstInBoundsGEP2_64(Counters, 0,
Edge);
Value *Count = Builder.CreateLoad(Counter);
Count = Builder.CreateAdd(Count,
ConstantInt::get(Type::getInt64Ty(*Ctx),1));
Builder.CreateStore(Count, Counter);
} else if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
Value *Sel = Builder.CreateSelect(
BI->getCondition(),
ConstantInt::get(Type::getInt64Ty(*Ctx), Edge),
ConstantInt::get(Type::getInt64Ty(*Ctx), Edge + 1));
SmallVector<Value *, 2> Idx;
Idx.push_back(Constant::getNullValue(Type::getInt64Ty(*Ctx)));
Idx.push_back(Sel);
Value *Counter = Builder.CreateInBoundsGEP(Counters,
Idx.begin(), Idx.end());
Value *Count = Builder.CreateLoad(Counter);
Count = Builder.CreateAdd(Count,
ConstantInt::get(Type::getInt64Ty(*Ctx),1));
Builder.CreateStore(Count, Counter);
} else {
ComplexEdgePreds.insert(BB);
for (int i = 0; i != Successors; ++i)
ComplexEdgeSuccs.insert(TI->getSuccessor(i));
}
Edge += Successors;
}
}
if (!ComplexEdgePreds.empty()) {
GlobalVariable *EdgeTable =
buildEdgeLookupTable(F, Counters,
ComplexEdgePreds, ComplexEdgeSuccs);
GlobalVariable *EdgeState = getEdgeStateValue();
const Type *Int32Ty = Type::getInt32Ty(*Ctx);
for (int i = 0, e = ComplexEdgePreds.size(); i != e; ++i) {
IRBuilder<> Builder(ComplexEdgePreds[i+1]->getTerminator());
Builder.CreateStore(ConstantInt::get(Int32Ty, i), EdgeState);
}
for (int i = 0, e = ComplexEdgeSuccs.size(); i != e; ++i) {
// call runtime to perform increment
IRBuilder<> Builder(ComplexEdgeSuccs[i+1]->getFirstNonPHI());
Value *CounterPtrArray =
Builder.CreateConstInBoundsGEP2_64(EdgeTable, 0,
i * ComplexEdgePreds.size());
Builder.CreateCall2(getIncrementIndirectCounterFunc(),
EdgeState, CounterPtrArray);
// clear the predecessor number
Builder.CreateStore(ConstantInt::get(Int32Ty, 0xffffffff), EdgeState);
}
}
}
insertCounterWriteout(DIF, CountersByIdent);
return true;
}
// All edges with successors that aren't branches are "complex", because it
// requires complex logic to pick which counter to update.
GlobalVariable *GCOVProfiler::buildEdgeLookupTable(
Function *F,
GlobalVariable *Counters,
const UniqueVector<BasicBlock *> &Preds,
const UniqueVector<BasicBlock *> &Succs) {
// TODO: support invoke, threads. We rely on the fact that nothing can modify
// the whole-Module pred edge# between the time we set it and the time we next
// read it. Threads and invoke make this untrue.
// emit [(succs * preds) x i64*], logically [succ x [pred x i64*]].
const Type *Int64PtrTy = Type::getInt64PtrTy(*Ctx);
const ArrayType *EdgeTableTy = ArrayType::get(
Int64PtrTy, Succs.size() * Preds.size());
Constant **EdgeTable = new Constant*[Succs.size() * Preds.size()];
Constant *NullValue = Constant::getNullValue(Int64PtrTy);
for (int i = 0, ie = Succs.size() * Preds.size(); i != ie; ++i)
EdgeTable[i] = NullValue;
unsigned Edge = 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 > 1 && !isa<BranchInst>(TI) && !isa<ReturnInst>(TI)) {
for (int i = 0; i != Successors; ++i) {
BasicBlock *Succ = TI->getSuccessor(i);
IRBuilder<> builder(Succ);
Value *Counter = builder.CreateConstInBoundsGEP2_64(Counters, 0,
Edge + i);
EdgeTable[((Succs.idFor(Succ)-1) * Preds.size()) +
(Preds.idFor(BB)-1)] = cast<Constant>(Counter);
}
}
Edge += Successors;
}
GlobalVariable *EdgeTableGV =
new GlobalVariable(
*M, EdgeTableTy, true, GlobalValue::InternalLinkage,
ConstantArray::get(EdgeTableTy,
&EdgeTable[0], Succs.size() * Preds.size()),
"__llvm_gcda_edge_table");
EdgeTableGV->setUnnamedAddr(true);
return EdgeTableGV;
}
Constant *GCOVProfiler::getStartFileFunc() {
const Type *Args[] = { Type::getInt8PtrTy(*Ctx) };
const FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx),
Args, false);
return M->getOrInsertFunction("llvm_gcda_start_file", FTy);
}
Constant *GCOVProfiler::getIncrementIndirectCounterFunc() {
const Type *Args[] = {
Type::getInt32PtrTy(*Ctx), // uint32_t *predecessor
Type::getInt64PtrTy(*Ctx)->getPointerTo(), // uint64_t **state_table_row
};
const FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx),
Args, false);
return M->getOrInsertFunction("llvm_gcda_increment_indirect_counter", FTy);
}
Constant *GCOVProfiler::getEmitFunctionFunc() {
const Type *Args[] = { Type::getInt32Ty(*Ctx) };
const FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx),
Args, false);
return M->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 M->getOrInsertFunction("llvm_gcda_emit_arcs", FTy);
}
Constant *GCOVProfiler::getEndFileFunc() {
const FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), false);
return M->getOrInsertFunction("llvm_gcda_end_file", FTy);
}
GlobalVariable *GCOVProfiler::getEdgeStateValue() {
GlobalVariable *GV = M->getGlobalVariable("__llvm_gcov_global_state_pred");
if (!GV) {
GV = new GlobalVariable(*M, Type::getInt32Ty(*Ctx), false,
GlobalValue::InternalLinkage,
ConstantInt::get(Type::getInt32Ty(*Ctx),
0xffffffff),
"__llvm_gcov_global_state_pred");
GV->setUnnamedAddr(true);
}
return GV;
}
void GCOVProfiler::insertCounterWriteout(
DebugInfoFinder &DIF,
SmallVector<std::pair<GlobalVariable *, uint32_t>, 8> &CountersByIdent) {
const FunctionType *WriteoutFTy =
FunctionType::get(Type::getVoidTy(*Ctx), false);
Function *WriteoutF = Function::Create(WriteoutFTy,
GlobalValue::InternalLinkage,
"__llvm_gcov_writeout", M);
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 FilenameGcda = replaceStem(compile_unit.getFilename(), "gcda");
Builder.CreateCall(StartFile,
Builder.CreateGlobalStringPtr(FilenameGcda));
for (SmallVector<std::pair<GlobalVariable *, uint32_t>, 8>::iterator
I = CountersByIdent.begin(), E = CountersByIdent.end();
I != E; ++I) {
Builder.CreateCall(EmitFunction, ConstantInt::get(Type::getInt32Ty(*Ctx),
I->second));
GlobalVariable *GV = I->first;
unsigned Arcs =
cast<ArrayType>(GV->getType()->getElementType())->getNumElements();
Builder.CreateCall2(EmitArcs,
ConstantInt::get(Type::getInt32Ty(*Ctx), Arcs),
Builder.CreateConstGEP2_64(GV, 0, 0));
}
Builder.CreateCall(EndFile);
}
Builder.CreateRetVoid();
InsertProfilingShutdownCall(WriteoutF, M);
}
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