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llvm-project/llvm/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.
//
//===----------------------------------------------------------------------===//
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/Hashing.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/UniqueVector.h"
#include "llvm/IR/DebugInfo.h"
#include "llvm/IR/DebugLoc.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/InstIterator.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Module.h"
#include "llvm/Pass.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/GCOVProfiler.h"
#include "llvm/Transforms/Instrumentation.h"
#include "llvm/Transforms/Utils/ModuleUtils.h"
#include <algorithm>
#include <memory>
#include <string>
#include <utility>
using namespace llvm;
#define DEBUG_TYPE "insert-gcov-profiling"
static cl::opt<std::string>
DefaultGCOVVersion("default-gcov-version", cl::init("402*"), cl::Hidden,
cl::ValueRequired);
static cl::opt<bool> DefaultExitBlockBeforeBody("gcov-exit-block-before-body",
cl::init(false), cl::Hidden);
GCOVOptions GCOVOptions::getDefault() {
GCOVOptions Options;
Options.EmitNotes = true;
Options.EmitData = true;
Options.UseCfgChecksum = false;
Options.NoRedZone = false;
Options.FunctionNamesInData = true;
Options.ExitBlockBeforeBody = DefaultExitBlockBeforeBody;
if (DefaultGCOVVersion.size() != 4) {
llvm::report_fatal_error(std::string("Invalid -default-gcov-version: ") +
DefaultGCOVVersion);
}
memcpy(Options.Version, DefaultGCOVVersion.c_str(), 4);
return Options;
}
namespace {
class GCOVFunction;
class GCOVProfiler {
public:
GCOVProfiler() : GCOVProfiler(GCOVOptions::getDefault()) {}
GCOVProfiler(const GCOVOptions &Opts) : Options(Opts) {
assert((Options.EmitNotes || Options.EmitData) &&
"GCOVProfiler asked to do nothing?");
ReversedVersion[0] = Options.Version[3];
ReversedVersion[1] = Options.Version[2];
ReversedVersion[2] = Options.Version[1];
ReversedVersion[3] = Options.Version[0];
ReversedVersion[4] = '\0';
}
bool runOnModule(Module &M);
private:
// Create the .gcno files for the Module based on DebugInfo.
void emitProfileNotes();
// Modify the program to track transitions along edges and call into the
// profiling runtime to emit .gcda files when run.
bool emitProfileArcs();
// Get pointers to the functions in the runtime library.
Constant *getStartFileFunc();
Constant *getIncrementIndirectCounterFunc();
Constant *getEmitFunctionFunc();
Constant *getEmitArcsFunc();
Constant *getSummaryInfoFunc();
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.
Function *
insertCounterWriteout(ArrayRef<std::pair<GlobalVariable *, MDNode *>>);
Function *insertFlush(ArrayRef<std::pair<GlobalVariable *, MDNode *>>);
void insertIndirectCounterIncrement();
std::string mangleName(const DICompileUnit *CU, const char *NewStem);
GCOVOptions Options;
// Reversed, NUL-terminated copy of Options.Version.
char ReversedVersion[5];
// Checksum, produced by hash of EdgeDestinations
SmallVector<uint32_t, 4> FileChecksums;
Module *M;
LLVMContext *Ctx;
SmallVector<std::unique_ptr<GCOVFunction>, 16> Funcs;
};
class GCOVProfilerLegacyPass : public ModulePass {
public:
static char ID;
GCOVProfilerLegacyPass()
: GCOVProfilerLegacyPass(GCOVOptions::getDefault()) {}
GCOVProfilerLegacyPass(const GCOVOptions &Opts)
: ModulePass(ID), Profiler(Opts) {
initializeGCOVProfilerLegacyPassPass(*PassRegistry::getPassRegistry());
}
const char *getPassName() const override { return "GCOV Profiler"; }
bool runOnModule(Module &M) override { return Profiler.runOnModule(M); }
private:
GCOVProfiler Profiler;
};
}
char GCOVProfilerLegacyPass::ID = 0;
INITIALIZE_PASS(GCOVProfilerLegacyPass, "insert-gcov-profiling",
"Insert instrumentation for GCOV profiling", false, false)
ModulePass *llvm::createGCOVProfilerPass(const GCOVOptions &Options) {
return new GCOVProfilerLegacyPass(Options);
}
static StringRef getFunctionName(const DISubprogram *SP) {
if (!SP->getLinkageName().empty())
return SP->getLinkageName();
return SP->getName();
}
namespace {
class GCOVRecord {
protected:
static const char *const LinesTag;
static const char *const FunctionTag;
static const char *const BlockTag;
static const char *const EdgeTag;
GCOVRecord() = default;
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
static 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() / 4) + 1;
}
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 *const GCOVRecord::LinesTag = "\0\0\x45\x01";
const char *const GCOVRecord::FunctionTag = "\0\0\0\1";
const char *const GCOVRecord::BlockTag = "\0\0\x41\x01";
const char *const 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) {
assert(Line != 0 && "Line zero is not a valid real line number.");
Lines.push_back(Line);
}
uint32_t length() const {
// Here 2 = 1 for string length + 1 for '0' id#.
return lengthOfGCOVString(Filename) + 2 + Lines.size();
}
void writeOut() {
write(0);
writeGCOVString(Filename);
for (int i = 0, e = Lines.size(); i != e; ++i)
write(Lines[i]);
}
GCOVLines(StringRef F, raw_ostream *os)
: Filename(F) {
this->os = os;
}
private:
StringRef 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(StringRef 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;
SmallVector<StringMapEntry<GCOVLines *> *, 32> SortedLinesByFile;
for (StringMap<GCOVLines *>::iterator I = LinesByFile.begin(),
E = LinesByFile.end(); I != E; ++I) {
Len += I->second->length();
SortedLinesByFile.push_back(&*I);
}
writeBytes(LinesTag, 4);
write(Len);
write(Number);
std::sort(SortedLinesByFile.begin(), SortedLinesByFile.end(),
[](StringMapEntry<GCOVLines *> *LHS,
StringMapEntry<GCOVLines *> *RHS) {
return LHS->getKey() < RHS->getKey();
});
for (SmallVectorImpl<StringMapEntry<GCOVLines *> *>::iterator
I = SortedLinesByFile.begin(), E = SortedLinesByFile.end();
I != E; ++I)
(*I)->getValue()->writeOut();
write(0);
write(0);
}
~GCOVBlock() {
DeleteContainerSeconds(LinesByFile);
}
GCOVBlock(const GCOVBlock &RHS) : GCOVRecord(RHS), Number(RHS.Number) {
// Only allow copy before edges and lines have been added. After that,
// there are inter-block pointers (eg: edges) that won't take kindly to
// blocks being copied or moved around.
assert(LinesByFile.empty());
assert(OutEdges.empty());
}
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(const DISubprogram *SP, Function *F, raw_ostream *os,
uint32_t Ident, bool UseCfgChecksum, bool ExitBlockBeforeBody)
: SP(SP), Ident(Ident), UseCfgChecksum(UseCfgChecksum), CfgChecksum(0),
ReturnBlock(1, os) {
this->os = os;
DEBUG(dbgs() << "Function: " << getFunctionName(SP) << "\n");
uint32_t i = 0;
for (auto &BB : *F) {
// Skip index 1 if it's assigned to the ReturnBlock.
if (i == 1 && ExitBlockBeforeBody)
++i;
Blocks.insert(std::make_pair(&BB, GCOVBlock(i++, os)));
}
if (!ExitBlockBeforeBody)
ReturnBlock.Number = i;
std::string FunctionNameAndLine;
raw_string_ostream FNLOS(FunctionNameAndLine);
FNLOS << getFunctionName(SP) << SP->getLine();
FNLOS.flush();
FuncChecksum = hash_value(FunctionNameAndLine);
}
GCOVBlock &getBlock(BasicBlock *BB) {
return Blocks.find(BB)->second;
}
GCOVBlock &getReturnBlock() {
return ReturnBlock;
}
std::string getEdgeDestinations() {
std::string EdgeDestinations;
raw_string_ostream EDOS(EdgeDestinations);
Function *F = Blocks.begin()->first->getParent();
for (BasicBlock &I : *F) {
GCOVBlock &Block = getBlock(&I);
for (int i = 0, e = Block.OutEdges.size(); i != e; ++i)
EDOS << Block.OutEdges[i]->Number;
}
return EdgeDestinations;
}
uint32_t getFuncChecksum() {
return FuncChecksum;
}
void setCfgChecksum(uint32_t Checksum) {
CfgChecksum = Checksum;
}
void writeOut() {
writeBytes(FunctionTag, 4);
uint32_t BlockLen = 1 + 1 + 1 + lengthOfGCOVString(getFunctionName(SP)) +
1 + lengthOfGCOVString(SP->getFilename()) + 1;
if (UseCfgChecksum)
++BlockLen;
write(BlockLen);
write(Ident);
write(FuncChecksum);
if (UseCfgChecksum)
write(CfgChecksum);
writeGCOVString(getFunctionName(SP));
writeGCOVString(SP->getFilename());
write(SP->getLine());
// 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.
}
DEBUG(dbgs() << Blocks.size() << " blocks.\n");
// Emit edges between blocks.
if (Blocks.empty()) return;
Function *F = Blocks.begin()->first->getParent();
for (BasicBlock &I : *F) {
GCOVBlock &Block = getBlock(&I);
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) {
DEBUG(dbgs() << Block.Number << " -> " << Block.OutEdges[i]->Number
<< "\n");
write(Block.OutEdges[i]->Number);
write(0); // no flags
}
}
// Emit lines for each block.
for (BasicBlock &I : *F)
getBlock(&I).writeOut();
}
private:
const DISubprogram *SP;
uint32_t Ident;
uint32_t FuncChecksum;
bool UseCfgChecksum;
uint32_t CfgChecksum;
DenseMap<BasicBlock *, GCOVBlock> Blocks;
GCOVBlock ReturnBlock;
};
}
std::string GCOVProfiler::mangleName(const DICompileUnit *CU,
const char *NewStem) {
if (NamedMDNode *GCov = M->getNamedMetadata("llvm.gcov")) {
for (int i = 0, e = GCov->getNumOperands(); i != e; ++i) {
MDNode *N = GCov->getOperand(i);
if (N->getNumOperands() != 2) continue;
MDString *GCovFile = dyn_cast<MDString>(N->getOperand(0));
MDNode *CompileUnit = dyn_cast<MDNode>(N->getOperand(1));
if (!GCovFile || !CompileUnit) continue;
if (CompileUnit == CU) {
SmallString<128> Filename = GCovFile->getString();
sys::path::replace_extension(Filename, NewStem);
return Filename.str();
}
}
}
SmallString<128> Filename = CU->getFilename();
sys::path::replace_extension(Filename, NewStem);
StringRef FName = sys::path::filename(Filename);
SmallString<128> CurPath;
if (sys::fs::current_path(CurPath)) return FName;
sys::path::append(CurPath, FName);
return CurPath.str();
}
bool GCOVProfiler::runOnModule(Module &M) {
this->M = &M;
Ctx = &M.getContext();
if (Options.EmitNotes) emitProfileNotes();
if (Options.EmitData) return emitProfileArcs();
return false;
}
PreservedAnalyses GCOVProfilerPass::run(Module &M,
AnalysisManager<Module> &AM) {
GCOVProfiler Profiler(GCOVOpts);
if (!Profiler.runOnModule(M))
return PreservedAnalyses::all();
return PreservedAnalyses::none();
}
static bool functionHasLines(Function &F) {
// Check whether this function actually has any source lines. Not only
// do these waste space, they also can crash gcov.
for (auto &BB : F) {
for (auto &I : BB) {
// Debug intrinsic locations correspond to the location of the
// declaration, not necessarily any statements or expressions.
if (isa<DbgInfoIntrinsic>(&I)) continue;
const DebugLoc &Loc = I.getDebugLoc();
if (!Loc)
continue;
// Artificial lines such as calls to the global constructors.
if (Loc.getLine() == 0) continue;
return true;
}
}
return false;
}
void GCOVProfiler::emitProfileNotes() {
NamedMDNode *CU_Nodes = M->getNamedMetadata("llvm.dbg.cu");
if (!CU_Nodes) return;
for (unsigned i = 0, e = CU_Nodes->getNumOperands(); 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.
auto *CU = cast<DICompileUnit>(CU_Nodes->getOperand(i));
// Skip module skeleton (and module) CUs.
if (CU->getDWOId())
continue;
std::error_code EC;
raw_fd_ostream out(mangleName(CU, "gcno"), EC, sys::fs::F_None);
std::string EdgeDestinations;
unsigned FunctionIdent = 0;
for (auto &F : M->functions()) {
DISubprogram *SP = F.getSubprogram();
if (!SP) continue;
if (!functionHasLines(F)) continue;
// gcov expects every function to start with an entry block that has a
// single successor, so split the entry block to make sure of that.
BasicBlock &EntryBlock = F.getEntryBlock();
BasicBlock::iterator It = EntryBlock.begin();
while (isa<AllocaInst>(*It) || isa<DbgInfoIntrinsic>(*It))
++It;
EntryBlock.splitBasicBlock(It);
Funcs.push_back(make_unique<GCOVFunction>(SP, &F, &out, FunctionIdent++,
Options.UseCfgChecksum,
Options.ExitBlockBeforeBody));
GCOVFunction &Func = *Funcs.back();
for (auto &BB : F) {
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 (auto &I : BB) {
// Debug intrinsic locations correspond to the location of the
// declaration, not necessarily any statements or expressions.
if (isa<DbgInfoIntrinsic>(&I)) continue;
const DebugLoc &Loc = I.getDebugLoc();
if (!Loc)
continue;
// Artificial lines such as calls to the global constructors.
if (Loc.getLine() == 0) continue;
if (Line == Loc.getLine()) continue;
Line = Loc.getLine();
if (SP != getDISubprogram(Loc.getScope()))
continue;
GCOVLines &Lines = Block.getFile(SP->getFilename());
Lines.addLine(Loc.getLine());
}
}
EdgeDestinations += Func.getEdgeDestinations();
}
FileChecksums.push_back(hash_value(EdgeDestinations));
out.write("oncg", 4);
out.write(ReversedVersion, 4);
out.write(reinterpret_cast<char*>(&FileChecksums.back()), 4);
for (auto &Func : Funcs) {
Func->setCfgChecksum(FileChecksums.back());
Func->writeOut();
}
out.write("\0\0\0\0\0\0\0\0", 8); // EOF
out.close();
}
}
bool GCOVProfiler::emitProfileArcs() {
NamedMDNode *CU_Nodes = M->getNamedMetadata("llvm.dbg.cu");
if (!CU_Nodes) return false;
bool Result = false;
bool InsertIndCounterIncrCode = false;
for (unsigned i = 0, e = CU_Nodes->getNumOperands(); i != e; ++i) {
SmallVector<std::pair<GlobalVariable *, MDNode *>, 8> CountersBySP;
for (auto &F : M->functions()) {
DISubprogram *SP = F.getSubprogram();
if (!SP) continue;
if (!functionHasLines(F)) continue;
if (!Result) Result = true;
unsigned Edges = 0;
for (auto &BB : F) {
TerminatorInst *TI = BB.getTerminator();
if (isa<ReturnInst>(TI))
++Edges;
else
Edges += TI->getNumSuccessors();
}
ArrayType *CounterTy =
ArrayType::get(Type::getInt64Ty(*Ctx), Edges);
GlobalVariable *Counters =
new GlobalVariable(*M, CounterTy, false,
GlobalValue::InternalLinkage,
Constant::getNullValue(CounterTy),
"__llvm_gcov_ctr");
CountersBySP.push_back(std::make_pair(Counters, SP));
UniqueVector<BasicBlock *> ComplexEdgePreds;
UniqueVector<BasicBlock *> ComplexEdgeSuccs;
unsigned Edge = 0;
for (auto &BB : F) {
TerminatorInst *TI = BB.getTerminator();
int Successors = isa<ReturnInst>(TI) ? 1 : TI->getNumSuccessors();
if (Successors) {
if (Successors == 1) {
IRBuilder<> Builder(&*BB.getFirstInsertionPt());
Value *Counter = Builder.CreateConstInBoundsGEP2_64(Counters, 0,
Edge);
Value *Count = Builder.CreateLoad(Counter);
Count = Builder.CreateAdd(Count, Builder.getInt64(1));
Builder.CreateStore(Count, Counter);
} else if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
IRBuilder<> Builder(BI);
Value *Sel = Builder.CreateSelect(BI->getCondition(),
Builder.getInt64(Edge),
Builder.getInt64(Edge + 1));
SmallVector<Value *, 2> Idx;
Idx.push_back(Builder.getInt64(0));
Idx.push_back(Sel);
Value *Counter = Builder.CreateInBoundsGEP(Counters->getValueType(),
Counters, Idx);
Value *Count = Builder.CreateLoad(Counter);
Count = Builder.CreateAdd(Count, Builder.getInt64(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();
for (int i = 0, e = ComplexEdgePreds.size(); i != e; ++i) {
IRBuilder<> Builder(&*ComplexEdgePreds[i + 1]->getFirstInsertionPt());
Builder.CreateStore(Builder.getInt32(i), EdgeState);
}
for (int i = 0, e = ComplexEdgeSuccs.size(); i != e; ++i) {
// Call runtime to perform increment.
IRBuilder<> Builder(&*ComplexEdgeSuccs[i + 1]->getFirstInsertionPt());
Value *CounterPtrArray =
Builder.CreateConstInBoundsGEP2_64(EdgeTable, 0,
i * ComplexEdgePreds.size());
// Build code to increment the counter.
InsertIndCounterIncrCode = true;
Builder.CreateCall(getIncrementIndirectCounterFunc(),
{EdgeState, CounterPtrArray});
}
}
}
Function *WriteoutF = insertCounterWriteout(CountersBySP);
Function *FlushF = insertFlush(CountersBySP);
// Create a small bit of code that registers the "__llvm_gcov_writeout" to
// be executed at exit and the "__llvm_gcov_flush" function to be executed
// when "__gcov_flush" is called.
FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), false);
Function *F = Function::Create(FTy, GlobalValue::InternalLinkage,
"__llvm_gcov_init", M);
F->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
F->setLinkage(GlobalValue::InternalLinkage);
F->addFnAttr(Attribute::NoInline);
if (Options.NoRedZone)
F->addFnAttr(Attribute::NoRedZone);
BasicBlock *BB = BasicBlock::Create(*Ctx, "entry", F);
IRBuilder<> Builder(BB);
FTy = FunctionType::get(Type::getVoidTy(*Ctx), false);
Type *Params[] = {
PointerType::get(FTy, 0),
PointerType::get(FTy, 0)
};
FTy = FunctionType::get(Builder.getVoidTy(), Params, false);
// Initialize the environment and register the local writeout and flush
// functions.
Constant *GCOVInit = M->getOrInsertFunction("llvm_gcov_init", FTy);
Builder.CreateCall(GCOVInit, {WriteoutF, FlushF});
Builder.CreateRetVoid();
appendToGlobalCtors(*M, F, 0);
}
if (InsertIndCounterIncrCode)
insertIndirectCounterIncrement();
return Result;
}
// 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*]].
size_t TableSize = Succs.size() * Preds.size();
Type *Int64PtrTy = Type::getInt64PtrTy(*Ctx);
ArrayType *EdgeTableTy = ArrayType::get(Int64PtrTy, TableSize);
std::unique_ptr<Constant * []> EdgeTable(new Constant *[TableSize]);
Constant *NullValue = Constant::getNullValue(Int64PtrTy);
for (size_t i = 0; i != TableSize; ++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,
makeArrayRef(&EdgeTable[0],TableSize)),
"__llvm_gcda_edge_table");
EdgeTableGV->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
return EdgeTableGV;
}
Constant *GCOVProfiler::getStartFileFunc() {
Type *Args[] = {
Type::getInt8PtrTy(*Ctx), // const char *orig_filename
Type::getInt8PtrTy(*Ctx), // const char version[4]
Type::getInt32Ty(*Ctx), // uint32_t checksum
};
FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), Args, false);
return M->getOrInsertFunction("llvm_gcda_start_file", FTy);
}
Constant *GCOVProfiler::getIncrementIndirectCounterFunc() {
Type *Int32Ty = Type::getInt32Ty(*Ctx);
Type *Int64Ty = Type::getInt64Ty(*Ctx);
Type *Args[] = {
Int32Ty->getPointerTo(), // uint32_t *predecessor
Int64Ty->getPointerTo()->getPointerTo() // uint64_t **counters
};
FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), Args, false);
return M->getOrInsertFunction("__llvm_gcov_indirect_counter_increment", FTy);
}
Constant *GCOVProfiler::getEmitFunctionFunc() {
Type *Args[] = {
Type::getInt32Ty(*Ctx), // uint32_t ident
Type::getInt8PtrTy(*Ctx), // const char *function_name
Type::getInt32Ty(*Ctx), // uint32_t func_checksum
Type::getInt8Ty(*Ctx), // uint8_t use_extra_checksum
Type::getInt32Ty(*Ctx), // uint32_t cfg_checksum
};
FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), Args, false);
return M->getOrInsertFunction("llvm_gcda_emit_function", FTy);
}
Constant *GCOVProfiler::getEmitArcsFunc() {
Type *Args[] = {
Type::getInt32Ty(*Ctx), // uint32_t num_counters
Type::getInt64PtrTy(*Ctx), // uint64_t *counters
};
FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), Args, false);
return M->getOrInsertFunction("llvm_gcda_emit_arcs", FTy);
}
Constant *GCOVProfiler::getSummaryInfoFunc() {
FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), false);
return M->getOrInsertFunction("llvm_gcda_summary_info", FTy);
}
Constant *GCOVProfiler::getEndFileFunc() {
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(GlobalValue::UnnamedAddr::Global);
}
return GV;
}
Function *GCOVProfiler::insertCounterWriteout(
ArrayRef<std::pair<GlobalVariable *, MDNode *> > CountersBySP) {
FunctionType *WriteoutFTy = FunctionType::get(Type::getVoidTy(*Ctx), false);
Function *WriteoutF = M->getFunction("__llvm_gcov_writeout");
if (!WriteoutF)
WriteoutF = Function::Create(WriteoutFTy, GlobalValue::InternalLinkage,
"__llvm_gcov_writeout", M);
WriteoutF->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
WriteoutF->addFnAttr(Attribute::NoInline);
if (Options.NoRedZone)
WriteoutF->addFnAttr(Attribute::NoRedZone);
BasicBlock *BB = BasicBlock::Create(*Ctx, "entry", WriteoutF);
IRBuilder<> Builder(BB);
Constant *StartFile = getStartFileFunc();
Constant *EmitFunction = getEmitFunctionFunc();
Constant *EmitArcs = getEmitArcsFunc();
Constant *SummaryInfo = getSummaryInfoFunc();
Constant *EndFile = getEndFileFunc();
NamedMDNode *CU_Nodes = M->getNamedMetadata("llvm.dbg.cu");
if (CU_Nodes) {
for (unsigned i = 0, e = CU_Nodes->getNumOperands(); i != e; ++i) {
auto *CU = cast<DICompileUnit>(CU_Nodes->getOperand(i));
// Skip module skeleton (and module) CUs.
if (CU->getDWOId())
continue;
std::string FilenameGcda = mangleName(CU, "gcda");
uint32_t CfgChecksum = FileChecksums.empty() ? 0 : FileChecksums[i];
Builder.CreateCall(StartFile,
{Builder.CreateGlobalStringPtr(FilenameGcda),
Builder.CreateGlobalStringPtr(ReversedVersion),
Builder.getInt32(CfgChecksum)});
for (unsigned j = 0, e = CountersBySP.size(); j != e; ++j) {
auto *SP = cast_or_null<DISubprogram>(CountersBySP[j].second);
uint32_t FuncChecksum = Funcs.empty() ? 0 : Funcs[j]->getFuncChecksum();
Builder.CreateCall(
EmitFunction,
{Builder.getInt32(j),
Options.FunctionNamesInData
? Builder.CreateGlobalStringPtr(getFunctionName(SP))
: Constant::getNullValue(Builder.getInt8PtrTy()),
Builder.getInt32(FuncChecksum),
Builder.getInt8(Options.UseCfgChecksum),
Builder.getInt32(CfgChecksum)});
GlobalVariable *GV = CountersBySP[j].first;
unsigned Arcs =
cast<ArrayType>(GV->getValueType())->getNumElements();
Builder.CreateCall(EmitArcs, {Builder.getInt32(Arcs),
Builder.CreateConstGEP2_64(GV, 0, 0)});
}
Builder.CreateCall(SummaryInfo, {});
Builder.CreateCall(EndFile, {});
}
}
Builder.CreateRetVoid();
return WriteoutF;
}
void GCOVProfiler::insertIndirectCounterIncrement() {
Function *Fn =
cast<Function>(GCOVProfiler::getIncrementIndirectCounterFunc());
Fn->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
Fn->setLinkage(GlobalValue::InternalLinkage);
Fn->addFnAttr(Attribute::NoInline);
if (Options.NoRedZone)
Fn->addFnAttr(Attribute::NoRedZone);
// Create basic blocks for function.
BasicBlock *BB = BasicBlock::Create(*Ctx, "entry", Fn);
IRBuilder<> Builder(BB);
BasicBlock *PredNotNegOne = BasicBlock::Create(*Ctx, "", Fn);
BasicBlock *CounterEnd = BasicBlock::Create(*Ctx, "", Fn);
BasicBlock *Exit = BasicBlock::Create(*Ctx, "exit", Fn);
// uint32_t pred = *predecessor;
// if (pred == 0xffffffff) return;
Argument *Arg = &*Fn->arg_begin();
Arg->setName("predecessor");
Value *Pred = Builder.CreateLoad(Arg, "pred");
Value *Cond = Builder.CreateICmpEQ(Pred, Builder.getInt32(0xffffffff));
BranchInst::Create(Exit, PredNotNegOne, Cond, BB);
Builder.SetInsertPoint(PredNotNegOne);
// uint64_t *counter = counters[pred];
// if (!counter) return;
Value *ZExtPred = Builder.CreateZExt(Pred, Builder.getInt64Ty());
Arg = &*std::next(Fn->arg_begin());
Arg->setName("counters");
Value *GEP = Builder.CreateGEP(Type::getInt64PtrTy(*Ctx), Arg, ZExtPred);
Value *Counter = Builder.CreateLoad(GEP, "counter");
Cond = Builder.CreateICmpEQ(Counter,
Constant::getNullValue(
Builder.getInt64Ty()->getPointerTo()));
Builder.CreateCondBr(Cond, Exit, CounterEnd);
// ++*counter;
Builder.SetInsertPoint(CounterEnd);
Value *Add = Builder.CreateAdd(Builder.CreateLoad(Counter),
Builder.getInt64(1));
Builder.CreateStore(Add, Counter);
Builder.CreateBr(Exit);
// Fill in the exit block.
Builder.SetInsertPoint(Exit);
Builder.CreateRetVoid();
}
Function *GCOVProfiler::
insertFlush(ArrayRef<std::pair<GlobalVariable*, MDNode*> > CountersBySP) {
FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), false);
Function *FlushF = M->getFunction("__llvm_gcov_flush");
if (!FlushF)
FlushF = Function::Create(FTy, GlobalValue::InternalLinkage,
"__llvm_gcov_flush", M);
else
FlushF->setLinkage(GlobalValue::InternalLinkage);
FlushF->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
FlushF->addFnAttr(Attribute::NoInline);
if (Options.NoRedZone)
FlushF->addFnAttr(Attribute::NoRedZone);
BasicBlock *Entry = BasicBlock::Create(*Ctx, "entry", FlushF);
// Write out the current counters.
Constant *WriteoutF = M->getFunction("__llvm_gcov_writeout");
assert(WriteoutF && "Need to create the writeout function first!");
IRBuilder<> Builder(Entry);
Builder.CreateCall(WriteoutF, {});
// Zero out the counters.
for (ArrayRef<std::pair<GlobalVariable *, MDNode *> >::iterator
I = CountersBySP.begin(), E = CountersBySP.end();
I != E; ++I) {
GlobalVariable *GV = I->first;
Constant *Null = Constant::getNullValue(GV->getValueType());
Builder.CreateStore(Null, GV);
}
Type *RetTy = FlushF->getReturnType();
if (RetTy == Type::getVoidTy(*Ctx))
Builder.CreateRetVoid();
else if (RetTy->isIntegerTy())
// Used if __llvm_gcov_flush was implicitly declared.
Builder.CreateRet(ConstantInt::get(RetTy, 0));
else
report_fatal_error("invalid return type for __llvm_gcov_flush");
return FlushF;
}
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