llvm-for-llvmta/tools/llvm-profgen/PerfReader.cpp

669 lines
24 KiB
C++

//===-- PerfReader.cpp - perfscript reader ---------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "PerfReader.h"
#include "ProfileGenerator.h"
static cl::opt<bool> ShowMmapEvents("show-mmap-events", cl::ReallyHidden,
cl::init(false), cl::ZeroOrMore,
cl::desc("Print binary load events."));
static cl::opt<bool> ShowUnwinderOutput("show-unwinder-output",
cl::ReallyHidden, cl::init(false),
cl::ZeroOrMore,
cl::desc("Print unwinder output"));
extern cl::opt<bool> ShowDisassemblyOnly;
extern cl::opt<bool> ShowSourceLocations;
namespace llvm {
namespace sampleprof {
void VirtualUnwinder::unwindCall(UnwindState &State) {
// The 2nd frame after leaf could be missing if stack sample is
// taken when IP is within prolog/epilog, as frame chain isn't
// setup yet. Fill in the missing frame in that case.
// TODO: Currently we just assume all the addr that can't match the
// 2nd frame is in prolog/epilog. In the future, we will switch to
// pro/epi tracker(Dwarf CFI) for the precise check.
uint64_t Source = State.getCurrentLBRSource();
auto *ParentFrame = State.getParentFrame();
if (ParentFrame == State.getDummyRootPtr() ||
ParentFrame->Address != Source) {
State.switchToFrame(Source);
} else {
State.popFrame();
}
State.InstPtr.update(Source);
}
void VirtualUnwinder::unwindLinear(UnwindState &State, uint64_t Repeat) {
InstructionPointer &IP = State.InstPtr;
uint64_t Target = State.getCurrentLBRTarget();
uint64_t End = IP.Address;
if (Binary->usePseudoProbes()) {
// We don't need to top frame probe since it should be extracted
// from the range.
// The outcome of the virtual unwinding with pseudo probes is a
// map from a context key to the address range being unwound.
// This means basically linear unwinding is not needed for pseudo
// probes. The range will be simply recorded here and will be
// converted to a list of pseudo probes to report in ProfileGenerator.
State.getParentFrame()->recordRangeCount(Target, End, Repeat);
} else {
// Unwind linear execution part
uint64_t LeafAddr = State.CurrentLeafFrame->Address;
while (IP.Address >= Target) {
uint64_t PrevIP = IP.Address;
IP.backward();
// Break into segments for implicit call/return due to inlining
bool SameInlinee = Binary->inlineContextEqual(PrevIP, IP.Address);
if (!SameInlinee || PrevIP == Target) {
State.switchToFrame(LeafAddr);
State.CurrentLeafFrame->recordRangeCount(PrevIP, End, Repeat);
End = IP.Address;
}
LeafAddr = IP.Address;
}
}
}
void VirtualUnwinder::unwindReturn(UnwindState &State) {
// Add extra frame as we unwind through the return
const LBREntry &LBR = State.getCurrentLBR();
uint64_t CallAddr = Binary->getCallAddrFromFrameAddr(LBR.Target);
State.switchToFrame(CallAddr);
State.pushFrame(LBR.Source);
State.InstPtr.update(LBR.Source);
}
void VirtualUnwinder::unwindBranchWithinFrame(UnwindState &State) {
// TODO: Tolerate tail call for now, as we may see tail call from libraries.
// This is only for intra function branches, excluding tail calls.
uint64_t Source = State.getCurrentLBRSource();
State.switchToFrame(Source);
State.InstPtr.update(Source);
}
std::shared_ptr<StringBasedCtxKey> FrameStack::getContextKey() {
std::shared_ptr<StringBasedCtxKey> KeyStr =
std::make_shared<StringBasedCtxKey>();
KeyStr->Context = Binary->getExpandedContextStr(Stack);
if (KeyStr->Context.empty())
return nullptr;
KeyStr->genHashCode();
return KeyStr;
}
std::shared_ptr<ProbeBasedCtxKey> ProbeStack::getContextKey() {
std::shared_ptr<ProbeBasedCtxKey> ProbeBasedKey =
std::make_shared<ProbeBasedCtxKey>();
for (auto CallProbe : Stack) {
ProbeBasedKey->Probes.emplace_back(CallProbe);
}
CSProfileGenerator::compressRecursionContext<const PseudoProbe *>(
ProbeBasedKey->Probes);
ProbeBasedKey->genHashCode();
return ProbeBasedKey;
}
template <typename T>
void VirtualUnwinder::collectSamplesFromFrame(UnwindState::ProfiledFrame *Cur,
T &Stack) {
if (Cur->RangeSamples.empty() && Cur->BranchSamples.empty())
return;
std::shared_ptr<ContextKey> Key = Stack.getContextKey();
if (Key == nullptr)
return;
auto Ret = CtxCounterMap->emplace(Hashable<ContextKey>(Key), SampleCounter());
SampleCounter &SCounter = Ret.first->second;
for (auto &Item : Cur->RangeSamples) {
uint64_t StartOffset = Binary->virtualAddrToOffset(std::get<0>(Item));
uint64_t EndOffset = Binary->virtualAddrToOffset(std::get<1>(Item));
SCounter.recordRangeCount(StartOffset, EndOffset, std::get<2>(Item));
}
for (auto &Item : Cur->BranchSamples) {
uint64_t SourceOffset = Binary->virtualAddrToOffset(std::get<0>(Item));
uint64_t TargetOffset = Binary->virtualAddrToOffset(std::get<1>(Item));
SCounter.recordBranchCount(SourceOffset, TargetOffset, std::get<2>(Item));
}
}
template <typename T>
void VirtualUnwinder::collectSamplesFromFrameTrie(
UnwindState::ProfiledFrame *Cur, T &Stack) {
if (!Cur->isDummyRoot()) {
if (!Stack.pushFrame(Cur)) {
// Process truncated context
for (const auto &Item : Cur->Children) {
// Start a new traversal ignoring its bottom context
collectSamplesFromFrameTrie(Item.second.get());
}
return;
}
}
collectSamplesFromFrame(Cur, Stack);
// Process children frame
for (const auto &Item : Cur->Children) {
collectSamplesFromFrameTrie(Item.second.get(), Stack);
}
// Recover the call stack
Stack.popFrame();
}
void VirtualUnwinder::collectSamplesFromFrameTrie(
UnwindState::ProfiledFrame *Cur) {
if (Binary->usePseudoProbes()) {
ProbeStack Stack(Binary);
collectSamplesFromFrameTrie<ProbeStack>(Cur, Stack);
} else {
FrameStack Stack(Binary);
collectSamplesFromFrameTrie<FrameStack>(Cur, Stack);
}
}
void VirtualUnwinder::recordBranchCount(const LBREntry &Branch,
UnwindState &State, uint64_t Repeat) {
if (Branch.IsArtificial)
return;
if (Binary->usePseudoProbes()) {
// Same as recordRangeCount, We don't need to top frame probe since we will
// extract it from branch's source address
State.getParentFrame()->recordBranchCount(Branch.Source, Branch.Target,
Repeat);
} else {
State.CurrentLeafFrame->recordBranchCount(Branch.Source, Branch.Target,
Repeat);
}
}
bool VirtualUnwinder::unwind(const HybridSample *Sample, uint64_t Repeat) {
// Capture initial state as starting point for unwinding.
UnwindState State(Sample);
// Sanity check - making sure leaf of LBR aligns with leaf of stack sample
// Stack sample sometimes can be unreliable, so filter out bogus ones.
if (!State.validateInitialState())
return false;
// Also do not attempt linear unwind for the leaf range as it's incomplete.
bool IsLeaf = true;
// Now process the LBR samples in parrallel with stack sample
// Note that we do not reverse the LBR entry order so we can
// unwind the sample stack as we walk through LBR entries.
while (State.hasNextLBR()) {
State.checkStateConsistency();
// Unwind implicit calls/returns from inlining, along the linear path,
// break into smaller sub section each with its own calling context.
if (!IsLeaf) {
unwindLinear(State, Repeat);
}
IsLeaf = false;
// Save the LBR branch before it gets unwound.
const LBREntry &Branch = State.getCurrentLBR();
if (isCallState(State)) {
// Unwind calls - we know we encountered call if LBR overlaps with
// transition between leaf the 2nd frame. Note that for calls that
// were not in the original stack sample, we should have added the
// extra frame when processing the return paired with this call.
unwindCall(State);
} else if (isReturnState(State)) {
// Unwind returns - check whether the IP is indeed at a return instruction
unwindReturn(State);
} else {
// Unwind branches - for regular intra function branches, we only
// need to record branch with context.
unwindBranchWithinFrame(State);
}
State.advanceLBR();
// Record `branch` with calling context after unwinding.
recordBranchCount(Branch, State, Repeat);
}
// As samples are aggregated on trie, record them into counter map
collectSamplesFromFrameTrie(State.getDummyRootPtr());
return true;
}
void PerfReader::validateCommandLine(
cl::list<std::string> &BinaryFilenames,
cl::list<std::string> &PerfTraceFilenames) {
// Allow the invalid perfscript if we only use to show binary disassembly
if (!ShowDisassemblyOnly) {
for (auto &File : PerfTraceFilenames) {
if (!llvm::sys::fs::exists(File)) {
std::string Msg = "Input perf script(" + File + ") doesn't exist!";
exitWithError(Msg);
}
}
}
if (BinaryFilenames.size() > 1) {
// TODO: remove this if everything is ready to support multiple binaries.
exitWithError(
"Currently only support one input binary, multiple binaries' "
"profile will be merged in one profile and make profile "
"summary info inaccurate. Please use `llvm-perfdata` to merge "
"profiles from multiple binaries.");
}
for (auto &Binary : BinaryFilenames) {
if (!llvm::sys::fs::exists(Binary)) {
std::string Msg = "Input binary(" + Binary + ") doesn't exist!";
exitWithError(Msg);
}
}
if (CSProfileGenerator::MaxCompressionSize < -1) {
exitWithError("Value of --compress-recursion should >= -1");
}
if (ShowSourceLocations && !ShowDisassemblyOnly) {
exitWithError("--show-source-locations should work together with "
"--show-disassembly-only!");
}
}
PerfReader::PerfReader(cl::list<std::string> &BinaryFilenames,
cl::list<std::string> &PerfTraceFilenames) {
validateCommandLine(BinaryFilenames, PerfTraceFilenames);
// Load the binaries.
for (auto Filename : BinaryFilenames)
loadBinary(Filename, /*AllowNameConflict*/ false);
}
ProfiledBinary &PerfReader::loadBinary(const StringRef BinaryPath,
bool AllowNameConflict) {
// The binary table is currently indexed by the binary name not the full
// binary path. This is because the user-given path may not match the one
// that was actually executed.
StringRef BinaryName = llvm::sys::path::filename(BinaryPath);
// Call to load the binary in the ctor of ProfiledBinary.
auto Ret = BinaryTable.insert({BinaryName, ProfiledBinary(BinaryPath)});
if (!Ret.second && !AllowNameConflict) {
std::string ErrorMsg = "Binary name conflict: " + BinaryPath.str() +
" and " + Ret.first->second.getPath().str() + " \n";
exitWithError(ErrorMsg);
}
return Ret.first->second;
}
void PerfReader::updateBinaryAddress(const MMapEvent &Event) {
// Load the binary.
StringRef BinaryPath = Event.BinaryPath;
StringRef BinaryName = llvm::sys::path::filename(BinaryPath);
auto I = BinaryTable.find(BinaryName);
// Drop the event which doesn't belong to user-provided binaries
// or if its image is loaded at the same address
if (I == BinaryTable.end() || Event.BaseAddress == I->second.getBaseAddress())
return;
ProfiledBinary &Binary = I->second;
// A binary image could be uploaded and then reloaded at different
// place, so update the address map here
AddrToBinaryMap.erase(Binary.getBaseAddress());
AddrToBinaryMap[Event.BaseAddress] = &Binary;
// Update binary load address.
Binary.setBaseAddress(Event.BaseAddress);
}
ProfiledBinary *PerfReader::getBinary(uint64_t Address) {
auto Iter = AddrToBinaryMap.lower_bound(Address);
if (Iter == AddrToBinaryMap.end() || Iter->first != Address) {
if (Iter == AddrToBinaryMap.begin())
return nullptr;
Iter--;
}
return Iter->second;
}
// Use ordered map to make the output deterministic
using OrderedCounterForPrint = std::map<std::string, RangeSample>;
static void printSampleCounter(OrderedCounterForPrint &OrderedCounter) {
for (auto Range : OrderedCounter) {
outs() << Range.first << "\n";
for (auto I : Range.second) {
outs() << " (" << format("%" PRIx64, I.first.first) << ", "
<< format("%" PRIx64, I.first.second) << "): " << I.second << "\n";
}
}
}
static std::string getContextKeyStr(ContextKey *K,
const ProfiledBinary *Binary) {
std::string ContextStr;
if (const auto *CtxKey = dyn_cast<StringBasedCtxKey>(K)) {
return CtxKey->Context;
} else if (const auto *CtxKey = dyn_cast<ProbeBasedCtxKey>(K)) {
SmallVector<std::string, 16> ContextStack;
for (const auto *Probe : CtxKey->Probes) {
Binary->getInlineContextForProbe(Probe, ContextStack, true);
}
for (const auto &Context : ContextStack) {
if (ContextStr.size())
ContextStr += " @ ";
ContextStr += Context;
}
}
return ContextStr;
}
static void printRangeCounter(ContextSampleCounterMap &Counter,
const ProfiledBinary *Binary) {
OrderedCounterForPrint OrderedCounter;
for (auto &CI : Counter) {
OrderedCounter[getContextKeyStr(CI.first.getPtr(), Binary)] =
CI.second.RangeCounter;
}
printSampleCounter(OrderedCounter);
}
static void printBranchCounter(ContextSampleCounterMap &Counter,
const ProfiledBinary *Binary) {
OrderedCounterForPrint OrderedCounter;
for (auto &CI : Counter) {
OrderedCounter[getContextKeyStr(CI.first.getPtr(), Binary)] =
CI.second.BranchCounter;
}
printSampleCounter(OrderedCounter);
}
void PerfReader::printUnwinderOutput() {
for (auto I : BinarySampleCounters) {
const ProfiledBinary *Binary = I.first;
outs() << "Binary(" << Binary->getName().str() << ")'s Range Counter:\n";
printRangeCounter(I.second, Binary);
outs() << "\nBinary(" << Binary->getName().str() << ")'s Branch Counter:\n";
printBranchCounter(I.second, Binary);
}
}
void PerfReader::unwindSamples() {
for (const auto &Item : AggregatedSamples) {
const HybridSample *Sample = dyn_cast<HybridSample>(Item.first.getPtr());
VirtualUnwinder Unwinder(&BinarySampleCounters[Sample->Binary],
Sample->Binary);
Unwinder.unwind(Sample, Item.second);
}
if (ShowUnwinderOutput)
printUnwinderOutput();
}
bool PerfReader::extractLBRStack(TraceStream &TraceIt,
SmallVectorImpl<LBREntry> &LBRStack,
ProfiledBinary *Binary) {
// The raw format of LBR stack is like:
// 0x4005c8/0x4005dc/P/-/-/0 0x40062f/0x4005b0/P/-/-/0 ...
// ... 0x4005c8/0x4005dc/P/-/-/0
// It's in FIFO order and seperated by whitespace.
SmallVector<StringRef, 32> Records;
TraceIt.getCurrentLine().split(Records, " ");
// Extract leading instruction pointer if present, use single
// list to pass out as reference.
size_t Index = 0;
if (!Records.empty() && Records[0].find('/') == StringRef::npos) {
Index = 1;
}
// Now extract LBR samples - note that we do not reverse the
// LBR entry order so we can unwind the sample stack as we walk
// through LBR entries.
uint64_t PrevTrDst = 0;
while (Index < Records.size()) {
auto &Token = Records[Index++];
if (Token.size() == 0)
continue;
SmallVector<StringRef, 8> Addresses;
Token.split(Addresses, "/");
uint64_t Src;
uint64_t Dst;
Addresses[0].substr(2).getAsInteger(16, Src);
Addresses[1].substr(2).getAsInteger(16, Dst);
bool SrcIsInternal = Binary->addressIsCode(Src);
bool DstIsInternal = Binary->addressIsCode(Dst);
bool IsArtificial = false;
// Ignore branches outside the current binary.
if (!SrcIsInternal && !DstIsInternal)
continue;
if (!SrcIsInternal && DstIsInternal) {
// For transition from external code (such as dynamic libraries) to
// the current binary, keep track of the branch target which will be
// grouped with the Source of the last transition from the current
// binary.
PrevTrDst = Dst;
continue;
}
if (SrcIsInternal && !DstIsInternal) {
// For transition to external code, group the Source with the next
// availabe transition target.
if (!PrevTrDst)
continue;
Dst = PrevTrDst;
PrevTrDst = 0;
IsArtificial = true;
}
// TODO: filter out buggy duplicate branches on Skylake
LBRStack.emplace_back(LBREntry(Src, Dst, IsArtificial));
}
TraceIt.advance();
return !LBRStack.empty();
}
bool PerfReader::extractCallstack(TraceStream &TraceIt,
SmallVectorImpl<uint64_t> &CallStack) {
// The raw format of call stack is like:
// 4005dc # leaf frame
// 400634
// 400684 # root frame
// It's in bottom-up order with each frame in one line.
// Extract stack frames from sample
ProfiledBinary *Binary = nullptr;
while (!TraceIt.isAtEoF() && !TraceIt.getCurrentLine().startswith(" 0x")) {
StringRef FrameStr = TraceIt.getCurrentLine().ltrim();
uint64_t FrameAddr = 0;
if (FrameStr.getAsInteger(16, FrameAddr)) {
// We might parse a non-perf sample line like empty line and comments,
// skip it
TraceIt.advance();
return false;
}
TraceIt.advance();
if (!Binary) {
Binary = getBinary(FrameAddr);
// we might have addr not match the MMAP, skip it
if (!Binary) {
if (AddrToBinaryMap.size() == 0)
WithColor::warning() << "No MMAP event in the perfscript, create it "
"with '--show-mmap-events'\n";
break;
}
}
// Currently intermixed frame from different binaries is not supported.
// Ignore bottom frames not from binary of interest.
if (!Binary->addressIsCode(FrameAddr))
break;
// We need to translate return address to call address
// for non-leaf frames
if (!CallStack.empty()) {
FrameAddr = Binary->getCallAddrFromFrameAddr(FrameAddr);
}
CallStack.emplace_back(FrameAddr);
}
// Skip other unrelated line, find the next valid LBR line
// Note that even for empty call stack, we should skip the address at the
// bottom, otherwise the following pass may generate a truncated callstack
while (!TraceIt.isAtEoF() && !TraceIt.getCurrentLine().startswith(" 0x")) {
TraceIt.advance();
}
// Filter out broken stack sample. We may not have complete frame info
// if sample end up in prolog/epilog, the result is dangling context not
// connected to entry point. This should be relatively rare thus not much
// impact on overall profile quality. However we do want to filter them
// out to reduce the number of different calling contexts. One instance
// of such case - when sample landed in prolog/epilog, somehow stack
// walking will be broken in an unexpected way that higher frames will be
// missing.
return !CallStack.empty() &&
!Binary->addressInPrologEpilog(CallStack.front());
}
void PerfReader::parseHybridSample(TraceStream &TraceIt) {
// The raw hybird sample started with call stack in FILO order and followed
// intermediately by LBR sample
// e.g.
// 4005dc # call stack leaf
// 400634
// 400684 # call stack root
// 0x4005c8/0x4005dc/P/-/-/0 0x40062f/0x4005b0/P/-/-/0 ...
// ... 0x4005c8/0x4005dc/P/-/-/0 # LBR Entries
//
std::shared_ptr<HybridSample> Sample = std::make_shared<HybridSample>();
// Parsing call stack and populate into HybridSample.CallStack
if (!extractCallstack(TraceIt, Sample->CallStack)) {
// Skip the next LBR line matched current call stack
if (!TraceIt.isAtEoF() && TraceIt.getCurrentLine().startswith(" 0x"))
TraceIt.advance();
return;
}
// Set the binary current sample belongs to
Sample->Binary = getBinary(Sample->CallStack.front());
if (!TraceIt.isAtEoF() && TraceIt.getCurrentLine().startswith(" 0x")) {
// Parsing LBR stack and populate into HybridSample.LBRStack
if (extractLBRStack(TraceIt, Sample->LBRStack, Sample->Binary)) {
// Canonicalize stack leaf to avoid 'random' IP from leaf frame skew LBR
// ranges
Sample->CallStack.front() = Sample->LBRStack[0].Target;
// Record samples by aggregation
Sample->genHashCode();
AggregatedSamples[Hashable<PerfSample>(Sample)]++;
}
} else {
// LBR sample is encoded in single line after stack sample
exitWithError("'Hybrid perf sample is corrupted, No LBR sample line");
}
}
void PerfReader::parseMMap2Event(TraceStream &TraceIt) {
// Parse a line like:
// PERF_RECORD_MMAP2 2113428/2113428: [0x7fd4efb57000(0x204000) @ 0
// 08:04 19532229 3585508847]: r-xp /usr/lib64/libdl-2.17.so
constexpr static const char *const Pattern =
"PERF_RECORD_MMAP2 ([0-9]+)/[0-9]+: "
"\\[(0x[a-f0-9]+)\\((0x[a-f0-9]+)\\) @ "
"(0x[a-f0-9]+|0) .*\\]: [-a-z]+ (.*)";
// Field 0 - whole line
// Field 1 - PID
// Field 2 - base address
// Field 3 - mmapped size
// Field 4 - page offset
// Field 5 - binary path
enum EventIndex {
WHOLE_LINE = 0,
PID = 1,
BASE_ADDRESS = 2,
MMAPPED_SIZE = 3,
PAGE_OFFSET = 4,
BINARY_PATH = 5
};
Regex RegMmap2(Pattern);
SmallVector<StringRef, 6> Fields;
bool R = RegMmap2.match(TraceIt.getCurrentLine(), &Fields);
if (!R) {
std::string ErrorMsg = "Cannot parse mmap event: Line" +
Twine(TraceIt.getLineNumber()).str() + ": " +
TraceIt.getCurrentLine().str() + " \n";
exitWithError(ErrorMsg);
}
MMapEvent Event;
Fields[PID].getAsInteger(10, Event.PID);
Fields[BASE_ADDRESS].getAsInteger(0, Event.BaseAddress);
Fields[MMAPPED_SIZE].getAsInteger(0, Event.Size);
Fields[PAGE_OFFSET].getAsInteger(0, Event.Offset);
Event.BinaryPath = Fields[BINARY_PATH];
updateBinaryAddress(Event);
if (ShowMmapEvents) {
outs() << "Mmap: Binary " << Event.BinaryPath << " loaded at "
<< format("0x%" PRIx64 ":", Event.BaseAddress) << " \n";
}
TraceIt.advance();
}
void PerfReader::parseEventOrSample(TraceStream &TraceIt) {
if (TraceIt.getCurrentLine().startswith("PERF_RECORD_MMAP2"))
parseMMap2Event(TraceIt);
else if (getPerfScriptType() == PERF_LBR_STACK)
parseHybridSample(TraceIt);
else {
// TODO: parse other type sample
TraceIt.advance();
}
}
void PerfReader::parseAndAggregateTrace(StringRef Filename) {
// Trace line iterator
TraceStream TraceIt(Filename);
while (!TraceIt.isAtEoF())
parseEventOrSample(TraceIt);
}
void PerfReader::checkAndSetPerfType(
cl::list<std::string> &PerfTraceFilenames) {
for (auto FileName : PerfTraceFilenames) {
PerfScriptType Type = checkPerfScriptType(FileName);
if (Type == PERF_INVALID)
exitWithError("Invalid perf script input!");
if (PerfType != PERF_UNKNOWN && PerfType != Type)
exitWithError("Inconsistent sample among different perf scripts");
PerfType = Type;
}
}
void PerfReader::generateRawProfile() {
if (getPerfScriptType() == PERF_LBR_STACK) {
// Unwind samples if it's hybird sample
unwindSamples();
} else if (getPerfScriptType() == PERF_LBR) {
// TODO: range overlap computation for regular AutoFDO
}
}
void PerfReader::parsePerfTraces(cl::list<std::string> &PerfTraceFilenames) {
// Check and set current perfscript type
checkAndSetPerfType(PerfTraceFilenames);
// Parse perf traces and do aggregation.
for (auto Filename : PerfTraceFilenames)
parseAndAggregateTrace(Filename);
generateRawProfile();
}
} // end namespace sampleprof
} // end namespace llvm