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llvm-mirror/lib/Transforms/Instrumentation/GCOVProfiling.cpp
Peter Collingbourne 5dcb77e9fb IR: Introduce local_unnamed_addr attribute. 
If a local_unnamed_addr attribute is attached to a global, the address
is known to be insignificant within the module. It is distinct from the
existing unnamed_addr attribute in that it only describes a local property
of the module rather than a global property of the symbol.

This attribute is intended to be used by the code generator and LTO to allow
the linker to decide whether the global needs to be in the symbol table. It is
possible to exclude a global from the symbol table if three things are true:
- This attribute is present on every instance of the global (which means that
  the normal rule that the global must have a unique address can be broken without
  being observable by the program by performing comparisons against the global's
  address)
- The global has linkonce_odr linkage (which means that each linkage unit must have
  its own copy of the global if it requires one, and the copy in each linkage unit
  must be the same)
- It is a constant or a function (which means that the program cannot observe that
  the unique-address rule has been broken by writing to the global)

Although this attribute could in principle be computed from the module
contents, LTO clients (i.e. linkers) will normally need to be able to compute
this property as part of symbol resolution, and it would be inefficient to
materialize every module just to compute it.

See:
http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20160509/356401.html
http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20160516/356738.html
for earlier discussion.

Part of the fix for PR27553.

Differential Revision: http://reviews.llvm.org/D20348

llvm-svn: 272709
2016-06-14 21:01:22 +00:00

1006 lines
35 KiB
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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 *getDeleteWriteoutFunctionListFunc();
Constant *getDeleteFlushFunctionListFunc();
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::getDeleteWriteoutFunctionListFunc() {
FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), false);
return M->getOrInsertFunction("llvm_delete_writeout_function_list", FTy);
}
Constant *GCOVProfiler::getDeleteFlushFunctionListFunc() {
FunctionType *FTy = FunctionType::get(Type::getVoidTy(*Ctx), false);
return M->getOrInsertFunction("llvm_delete_flush_function_list", 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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