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llvm-project/llvm/tools/llvm-profgen/PerfReader.cpp

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//===-- 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"
#include "llvm/DebugInfo/Symbolize/SymbolizableModule.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/Process.h"
#define DEBUG_TYPE "perf-reader"
cl::opt<bool> SkipSymbolization("skip-symbolization", cl::init(false),
cl::ZeroOrMore,
cl::desc("Dump the unsymbolized profile to the "
"output file. It will show unwinder "
"output for CS profile generation."));
static cl::opt<bool> ShowMmapEvents("show-mmap-events", cl::init(false),
cl::ZeroOrMore,
cl::desc("Print binary load events."));
static cl::opt<bool>
UseOffset("use-offset", cl::init(true), cl::ZeroOrMore,
cl::desc("Work with `--skip-symbolization` or "
"`--unsymbolized-profile` to write/read the "
"offset instead of virtual address."));
static cl::opt<bool> UseLoadableSegmentAsBase(
"use-first-loadable-segment-as-base", cl::init(false), cl::ZeroOrMore,
cl::desc("Use first loadable segment address as base address "
"for offsets in unsymbolized profile. By default "
"first executable segment address is used"));
static cl::opt<bool>
IgnoreStackSamples("ignore-stack-samples", cl::init(false), cl::ZeroOrMore,
cl::desc("Ignore call stack samples for hybrid samples "
"and produce context-insensitive profile."));
cl::opt<bool> ShowDetailedWarning("show-detailed-warning", cl::init(false),
cl::ZeroOrMore,
cl::desc("Show detailed warning message."));
extern cl::opt<std::string> PerfTraceFilename;
extern cl::opt<bool> ShowDisassemblyOnly;
extern cl::opt<bool> ShowSourceLocations;
extern cl::opt<std::string> OutputFilename;
namespace llvm {
namespace sampleprof {
void VirtualUnwinder::unwindCall(UnwindState &State) {
uint64_t Source = State.getCurrentLBRSource();
auto *ParentFrame = State.getParentFrame();
// 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.
if (ParentFrame == State.getDummyRootPtr() ||
ParentFrame->Address != Source) {
State.switchToFrame(Source);
if (ParentFrame != State.getDummyRootPtr()) {
if (Source == ExternalAddr)
NumMismatchedExtCallBranch++;
else
NumMismatchedProEpiBranch++;
}
} 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 (End == ExternalAddr && Target == ExternalAddr) {
// Filter out the case when leaf external frame matches the external LBR
// target, this is a valid state, it happens that the code run into external
// address then return back. The call frame under the external frame
// remains valid and can be unwound later, just skip recording this range.
NumPairedExtAddr++;
return;
}
if (End == ExternalAddr || Target == ExternalAddr) {
// Range is invalid if only one point is external address. This means LBR
// traces contains a standalone external address failing to pair another
// one, likely due to interrupt jmp or broken perf script. Set the
// state to invalid.
NumUnpairedExtAddr++;
State.setInvalid();
return;
}
if (!isValidFallThroughRange(Binary->virtualAddrToOffset(Target),
Binary->virtualAddrToOffset(End), Binary)) {
// Skip unwinding the rest of LBR trace when a bogus range is seen.
State.setInvalid();
return;
}
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.
// Split and record the range by different inline context. For example:
// [0x01] ... main:1 # Target
// [0x02] ... main:2
// [0x03] ... main:3 @ foo:1
// [0x04] ... main:3 @ foo:2
// [0x05] ... main:3 @ foo:3
// [0x06] ... main:4
// [0x07] ... main:5 # End
// It will be recorded:
// [main:*] : [0x06, 0x07], [0x01, 0x02]
// [main:3 @ foo:*] : [0x03, 0x05]
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) {
State.switchToFrame(PrevIP);
State.CurrentLeafFrame->recordRangeCount(PrevIP, End, Repeat);
End = IP.Address;
}
}
assert(IP.Address == Target && "The last one must be the target address.");
// Record the remaining range, [0x01, 0x02] in the example
State.switchToFrame(IP.Address);
State.CurrentLeafFrame->recordRangeCount(IP.Address, End, Repeat);
}
}
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::unwindBranch(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->getExpandedContext(Stack, KeyStr->WasLeafInlined);
return KeyStr;
}
std::shared_ptr<AddrBasedCtxKey> AddressStack::getContextKey() {
std::shared_ptr<AddrBasedCtxKey> KeyStr = std::make_shared<AddrBasedCtxKey>();
KeyStr->Context = Stack;
CSProfileGenerator::compressRecursionContext<uint64_t>(KeyStr->Context);
CSProfileGenerator::trimContext<uint64_t>(KeyStr->Context);
return KeyStr;
}
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()) {
// Truncate the context for external frame since this isn't a real call
// context the compiler will see.
if (Cur->isExternalFrame() || !Stack.pushFrame(Cur)) {
// Process truncated context
// Start a new traversal ignoring its bottom context
T EmptyStack(Binary);
collectSamplesFromFrame(Cur, EmptyStack);
for (const auto &Item : Cur->Children) {
collectSamplesFromFrameTrie(Item.second.get(), EmptyStack);
}
// Keep note of untracked call site and deduplicate them
// for warning later.
if (!Cur->isLeafFrame())
UntrackedCallsites.insert(Cur->Address);
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()) {
AddressStack Stack(Binary);
collectSamplesFromFrameTrie<AddressStack>(Cur, Stack);
} else {
FrameStack Stack(Binary);
collectSamplesFromFrameTrie<FrameStack>(Cur, Stack);
}
}
void VirtualUnwinder::recordBranchCount(const LBREntry &Branch,
UnwindState &State, uint64_t Repeat) {
if (Branch.Target == ExternalAddr)
return;
// Record external-to-internal pattern on the trie root, it later can be
// used for generating head samples.
if (Branch.Source == ExternalAddr) {
State.getDummyRootPtr()->recordBranchCount(Branch.Source, Branch.Target,
Repeat);
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 PerfSample *Sample, uint64_t Repeat) {
// Capture initial state as starting point for unwinding.
UnwindState State(Sample, Binary);
// 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;
NumTotalBranches += State.LBRStack.size();
// 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();
// Do not attempt linear unwind for the leaf range as it's incomplete.
if (!State.IsLastLBR()) {
// Unwind implicit calls/returns from inlining, along the linear path,
// break into smaller sub section each with its own calling context.
unwindLinear(State, Repeat);
}
// 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 if (isValidState(State)) {
// Unwind branches
unwindBranch(State);
} else {
// Skip unwinding the rest of LBR trace. Reset the stack and update the
// state so that the rest of the trace can still be processed as if they
// do not have stack samples.
State.clearCallStack();
State.InstPtr.update(State.getCurrentLBRSource());
State.pushFrame(State.InstPtr.Address);
}
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;
}
std::unique_ptr<PerfReaderBase>
PerfReaderBase::create(ProfiledBinary *Binary, PerfInputFile &PerfInput,
Optional<uint32_t> PIDFilter) {
std::unique_ptr<PerfReaderBase> PerfReader;
if (PerfInput.Format == PerfFormat::UnsymbolizedProfile) {
PerfReader.reset(
new UnsymbolizedProfileReader(Binary, PerfInput.InputFile));
return PerfReader;
}
// For perf data input, we need to convert them into perf script first.
if (PerfInput.Format == PerfFormat::PerfData)
PerfInput =
PerfScriptReader::convertPerfDataToTrace(Binary, PerfInput, PIDFilter);
assert((PerfInput.Format == PerfFormat::PerfScript) &&
"Should be a perfscript!");
PerfInput.Content =
PerfScriptReader::checkPerfScriptType(PerfInput.InputFile);
if (PerfInput.Content == PerfContent::LBRStack) {
PerfReader.reset(
new HybridPerfReader(Binary, PerfInput.InputFile, PIDFilter));
} else if (PerfInput.Content == PerfContent::LBR) {
PerfReader.reset(new LBRPerfReader(Binary, PerfInput.InputFile, PIDFilter));
} else {
exitWithError("Unsupported perfscript!");
}
return PerfReader;
}
PerfInputFile PerfScriptReader::convertPerfDataToTrace(
ProfiledBinary *Binary, PerfInputFile &File, Optional<uint32_t> PIDFilter) {
StringRef PerfData = File.InputFile;
// Run perf script to retrieve PIDs matching binary we're interested in.
auto PerfExecutable = sys::Process::FindInEnvPath("PATH", "perf");
if (!PerfExecutable) {
exitWithError("Perf not found.");
}
std::string PerfPath = *PerfExecutable;
std::string PerfTraceFile = PerfData.str() + ".script.tmp";
StringRef ScriptMMapArgs[] = {PerfPath, "script", "--show-mmap-events",
"-F", "comm,pid", "-i",
PerfData};
Optional<StringRef> Redirects[] = {llvm::None, // Stdin
StringRef(PerfTraceFile), // Stdout
StringRef(PerfTraceFile)}; // Stderr
sys::ExecuteAndWait(PerfPath, ScriptMMapArgs, llvm::None, Redirects);
// Collect the PIDs
TraceStream TraceIt(PerfTraceFile);
std::string PIDs;
std::unordered_set<uint32_t> PIDSet;
while (!TraceIt.isAtEoF()) {
MMapEvent MMap;
if (isMMap2Event(TraceIt.getCurrentLine()) &&
extractMMap2EventForBinary(Binary, TraceIt.getCurrentLine(), MMap)) {
auto It = PIDSet.emplace(MMap.PID);
if (It.second && (!PIDFilter || MMap.PID == *PIDFilter)) {
if (!PIDs.empty()) {
PIDs.append(",");
}
PIDs.append(utostr(MMap.PID));
}
}
TraceIt.advance();
}
if (PIDs.empty()) {
exitWithError("No relevant mmap event is found in perf data.");
}
// Run perf script again to retrieve events for PIDs collected above
StringRef ScriptSampleArgs[] = {PerfPath, "script", "--show-mmap-events",
"-F", "ip,brstack", "--pid",
PIDs, "-i", PerfData};
sys::ExecuteAndWait(PerfPath, ScriptSampleArgs, llvm::None, Redirects);
return {PerfTraceFile, PerfFormat::PerfScript, PerfContent::UnknownContent};
}
void PerfScriptReader::updateBinaryAddress(const MMapEvent &Event) {
// Drop the event which doesn't belong to user-provided binary
StringRef BinaryName = llvm::sys::path::filename(Event.BinaryPath);
if (Binary->getName() != BinaryName)
return;
// Drop the event if process does not match pid filter
if (PIDFilter && Event.PID != *PIDFilter)
return;
// Drop the event if its image is loaded at the same address
if (Event.Address == Binary->getBaseAddress()) {
Binary->setIsLoadedByMMap(true);
return;
}
if (Event.Offset == Binary->getTextSegmentOffset()) {
// A binary image could be unloaded and then reloaded at different
// place, so update binary load address.
// Only update for the first executable segment and assume all other
// segments are loaded at consecutive memory addresses, which is the case on
// X64.
Binary->setBaseAddress(Event.Address);
Binary->setIsLoadedByMMap(true);
} else {
// Verify segments are loaded consecutively.
const auto &Offsets = Binary->getTextSegmentOffsets();
auto It = std::lower_bound(Offsets.begin(), Offsets.end(), Event.Offset);
if (It != Offsets.end() && *It == Event.Offset) {
// The event is for loading a separate executable segment.
auto I = std::distance(Offsets.begin(), It);
const auto &PreferredAddrs = Binary->getPreferredTextSegmentAddresses();
if (PreferredAddrs[I] - Binary->getPreferredBaseAddress() !=
Event.Address - Binary->getBaseAddress())
exitWithError("Executable segments not loaded consecutively");
} else {
if (It == Offsets.begin())
exitWithError("File offset not found");
else {
// Find the segment the event falls in. A large segment could be loaded
// via multiple mmap calls with consecutive memory addresses.
--It;
assert(*It < Event.Offset);
if (Event.Offset - *It != Event.Address - Binary->getBaseAddress())
exitWithError("Segment not loaded by consecutive mmaps");
}
}
}
}
static std::string getContextKeyStr(ContextKey *K,
const ProfiledBinary *Binary) {
if (const auto *CtxKey = dyn_cast<StringBasedCtxKey>(K)) {
return SampleContext::getContextString(CtxKey->Context);
} else if (const auto *CtxKey = dyn_cast<AddrBasedCtxKey>(K)) {
std::ostringstream OContextStr;
for (uint32_t I = 0; I < CtxKey->Context.size(); I++) {
if (OContextStr.str().size())
OContextStr << " @ ";
OContextStr << "0x"
<< to_hexString(
Binary->virtualAddrToOffset(CtxKey->Context[I]),
false);
}
return OContextStr.str();
} else {
llvm_unreachable("unexpected key type");
}
}
void HybridPerfReader::unwindSamples() {
if (Binary->useFSDiscriminator())
exitWithError("FS discriminator is not supported in CS profile.");
VirtualUnwinder Unwinder(&SampleCounters, Binary);
for (const auto &Item : AggregatedSamples) {
const PerfSample *Sample = Item.first.getPtr();
Unwinder.unwind(Sample, Item.second);
}
// Warn about untracked frames due to missing probes.
if (ShowDetailedWarning) {
for (auto Address : Unwinder.getUntrackedCallsites())
WithColor::warning() << "Profile context truncated due to missing probe "
<< "for call instruction at "
<< format("0x%" PRIx64, Address) << "\n";
}
emitWarningSummary(Unwinder.getUntrackedCallsites().size(),
SampleCounters.size(),
"of profiled contexts are truncated due to missing probe "
"for call instruction.");
emitWarningSummary(
Unwinder.NumMismatchedExtCallBranch, Unwinder.NumTotalBranches,
"of branches'source is a call instruction but doesn't match call frame "
"stack, likely due to unwinding error of external frame.");
emitWarningSummary(Unwinder.NumPairedExtAddr * 2, Unwinder.NumTotalBranches,
"of branches containing paired external address.");
emitWarningSummary(Unwinder.NumUnpairedExtAddr, Unwinder.NumTotalBranches,
"of branches containing external address but doesn't have "
"another external address to pair, likely due to "
"interrupt jmp or broken perf script.");
emitWarningSummary(
Unwinder.NumMismatchedProEpiBranch, Unwinder.NumTotalBranches,
"of branches'source is a call instruction but doesn't match call frame "
"stack, likely due to frame in prolog/epilog.");
emitWarningSummary(Unwinder.NumMissingExternalFrame,
Unwinder.NumExtCallBranch,
"of artificial call branches but doesn't have an external "
"frame to match.");
}
bool PerfScriptReader::extractLBRStack(TraceStream &TraceIt,
SmallVectorImpl<LBREntry> &LBRStack) {
// 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, " ", -1, false);
auto WarnInvalidLBR = [](TraceStream &TraceIt) {
WithColor::warning() << "Invalid address in LBR record at line "
<< TraceIt.getLineNumber() << ": "
<< TraceIt.getCurrentLine() << "\n";
};
// Skip the leading instruction pointer.
size_t Index = 0;
uint64_t LeadingAddr;
if (!Records.empty() && !Records[0].contains('/')) {
if (Records[0].getAsInteger(16, LeadingAddr)) {
WarnInvalidLBR(TraceIt);
TraceIt.advance();
return false;
}
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.
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;
// Stop at broken LBR records.
if (Addresses.size() < 2 || Addresses[0].substr(2).getAsInteger(16, Src) ||
Addresses[1].substr(2).getAsInteger(16, Dst)) {
WarnInvalidLBR(TraceIt);
break;
}
bool SrcIsInternal = Binary->addressIsCode(Src);
bool DstIsInternal = Binary->addressIsCode(Dst);
if (!SrcIsInternal)
Src = ExternalAddr;
if (!DstIsInternal)
Dst = ExternalAddr;
// Filter external-to-external case to reduce LBR trace size.
if (!SrcIsInternal && !DstIsInternal)
continue;
LBRStack.emplace_back(LBREntry(Src, Dst));
}
TraceIt.advance();
return !LBRStack.empty();
}
bool PerfScriptReader::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
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();
// Currently intermixed frame from different binaries is not supported.
if (!Binary->addressIsCode(FrameAddr)) {
if (CallStack.empty())
NumLeafExternalFrame++;
// Push a special value(ExternalAddr) for the external frames so that
// unwinder can still work on this with artificial Call/Return branch.
// After unwinding, the context will be truncated for external frame.
// Also deduplicate the consecutive external addresses.
if (CallStack.empty() || CallStack.back() != ExternalAddr)
CallStack.emplace_back(ExternalAddr);
continue;
}
// We need to translate return address to call address for non-leaf frames.
if (!CallStack.empty()) {
auto CallAddr = Binary->getCallAddrFromFrameAddr(FrameAddr);
if (!CallAddr) {
// Stop at an invalid return address caused by bad unwinding. This could
// happen to frame-pointer-based unwinding and the callee functions that
// do not have the frame pointer chain set up.
InvalidReturnAddresses.insert(FrameAddr);
break;
}
FrameAddr = CallAddr;
}
CallStack.emplace_back(FrameAddr);
}
// Strip out the bottom external addr.
if (CallStack.size() > 1 && CallStack.back() == ExternalAddr)
CallStack.pop_back();
// 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 PerfScriptReader::warnIfMissingMMap() {
if (!Binary->getMissingMMapWarned() && !Binary->getIsLoadedByMMap()) {
WithColor::warning() << "No relevant mmap event is matched for "
<< Binary->getName()
<< ", will use preferred address ("
<< format("0x%" PRIx64,
Binary->getPreferredBaseAddress())
<< ") as the base loading address!\n";
// Avoid redundant warning, only warn at the first unmatched sample.
Binary->setMissingMMapWarned(true);
}
}
void HybridPerfReader::parseSample(TraceStream &TraceIt, uint64_t Count) {
// 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<PerfSample> Sample = std::make_shared<PerfSample>();
#ifndef NDEBUG
Sample->Linenum = TraceIt.getLineNumber();
#endif
// Parsing call stack and populate into PerfSample.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;
}
warnIfMissingMMap();
if (!TraceIt.isAtEoF() && TraceIt.getCurrentLine().startswith(" 0x")) {
// Parsing LBR stack and populate into PerfSample.LBRStack
if (extractLBRStack(TraceIt, Sample->LBRStack)) {
if (IgnoreStackSamples) {
Sample->CallStack.clear();
} else {
// Canonicalize stack leaf to avoid 'random' IP from leaf frame skew LBR
// ranges
Sample->CallStack.front() = Sample->LBRStack[0].Target;
}
// Record samples by aggregation
AggregatedSamples[Hashable<PerfSample>(Sample)] += Count;
}
} else {
// LBR sample is encoded in single line after stack sample
exitWithError("'Hybrid perf sample is corrupted, No LBR sample line");
}
}
void PerfScriptReader::writeUnsymbolizedProfile(StringRef Filename) {
std::error_code EC;
raw_fd_ostream OS(Filename, EC, llvm::sys::fs::OF_TextWithCRLF);
if (EC)
exitWithError(EC, Filename);
writeUnsymbolizedProfile(OS);
}
// Use ordered map to make the output deterministic
using OrderedCounterForPrint = std::map<std::string, SampleCounter *>;
void PerfScriptReader::writeUnsymbolizedProfile(raw_fd_ostream &OS) {
OrderedCounterForPrint OrderedCounters;
for (auto &CI : SampleCounters) {
OrderedCounters[getContextKeyStr(CI.first.getPtr(), Binary)] = &CI.second;
}
auto SCounterPrinter = [&](RangeSample &Counter, StringRef Separator,
uint32_t Indent) {
OS.indent(Indent);
OS << Counter.size() << "\n";
for (auto &I : Counter) {
uint64_t Start = I.first.first;
uint64_t End = I.first.second;
if (!UseOffset || (UseOffset && UseLoadableSegmentAsBase)) {
Start = Binary->offsetToVirtualAddr(Start);
End = Binary->offsetToVirtualAddr(End);
}
if (UseOffset && UseLoadableSegmentAsBase) {
Start -= Binary->getFirstLoadableAddress();
End -= Binary->getFirstLoadableAddress();
}
OS.indent(Indent);
OS << Twine::utohexstr(Start) << Separator << Twine::utohexstr(End) << ":"
<< I.second << "\n";
}
};
for (auto &CI : OrderedCounters) {
uint32_t Indent = 0;
if (ProfileIsCS) {
// Context string key
OS << "[" << CI.first << "]\n";
Indent = 2;
}
SampleCounter &Counter = *CI.second;
SCounterPrinter(Counter.RangeCounter, "-", Indent);
SCounterPrinter(Counter.BranchCounter, "->", Indent);
}
}
// Format of input:
// number of entries in RangeCounter
// from_1-to_1:count_1
// from_2-to_2:count_2
// ......
// from_n-to_n:count_n
// number of entries in BranchCounter
// src_1->dst_1:count_1
// src_2->dst_2:count_2
// ......
// src_n->dst_n:count_n
void UnsymbolizedProfileReader::readSampleCounters(TraceStream &TraceIt,
SampleCounter &SCounters) {
auto exitWithErrorForTraceLine = [](TraceStream &TraceIt) {
std::string Msg = TraceIt.isAtEoF()
? "Invalid raw profile!"
: "Invalid raw profile at line " +
Twine(TraceIt.getLineNumber()).str() + ": " +
TraceIt.getCurrentLine().str();
exitWithError(Msg);
};
auto ReadNumber = [&](uint64_t &Num) {
if (TraceIt.isAtEoF())
exitWithErrorForTraceLine(TraceIt);
if (TraceIt.getCurrentLine().ltrim().getAsInteger(10, Num))
exitWithErrorForTraceLine(TraceIt);
TraceIt.advance();
};
auto ReadCounter = [&](RangeSample &Counter, StringRef Separator) {
uint64_t Num = 0;
ReadNumber(Num);
while (Num--) {
if (TraceIt.isAtEoF())
exitWithErrorForTraceLine(TraceIt);
StringRef Line = TraceIt.getCurrentLine().ltrim();
uint64_t Count = 0;
auto LineSplit = Line.split(":");
if (LineSplit.second.empty() || LineSplit.second.getAsInteger(10, Count))
exitWithErrorForTraceLine(TraceIt);
uint64_t Source = 0;
uint64_t Target = 0;
auto Range = LineSplit.first.split(Separator);
if (Range.second.empty() || Range.first.getAsInteger(16, Source) ||
Range.second.getAsInteger(16, Target))
exitWithErrorForTraceLine(TraceIt);
if (!UseOffset || (UseOffset && UseLoadableSegmentAsBase)) {
uint64_t BaseAddr = 0;
if (UseOffset && UseLoadableSegmentAsBase)
BaseAddr = Binary->getFirstLoadableAddress();
Source = Binary->virtualAddrToOffset(Source + BaseAddr);
Target = Binary->virtualAddrToOffset(Target + BaseAddr);
}
Counter[{Source, Target}] += Count;
TraceIt.advance();
}
};
ReadCounter(SCounters.RangeCounter, "-");
ReadCounter(SCounters.BranchCounter, "->");
}
void UnsymbolizedProfileReader::readUnsymbolizedProfile(StringRef FileName) {
TraceStream TraceIt(FileName);
while (!TraceIt.isAtEoF()) {
std::shared_ptr<StringBasedCtxKey> Key =
std::make_shared<StringBasedCtxKey>();
StringRef Line = TraceIt.getCurrentLine();
// Read context stack for CS profile.
if (Line.startswith("[")) {
ProfileIsCS = true;
auto I = ContextStrSet.insert(Line.str());
SampleContext::createCtxVectorFromStr(*I.first, Key->Context);
TraceIt.advance();
}
auto Ret =
SampleCounters.emplace(Hashable<ContextKey>(Key), SampleCounter());
readSampleCounters(TraceIt, Ret.first->second);
}
}
void UnsymbolizedProfileReader::parsePerfTraces() {
readUnsymbolizedProfile(PerfTraceFile);
}
void PerfScriptReader::computeCounterFromLBR(const PerfSample *Sample,
uint64_t Repeat) {
SampleCounter &Counter = SampleCounters.begin()->second;
uint64_t EndOffeset = 0;
for (const LBREntry &LBR : Sample->LBRStack) {
uint64_t SourceOffset = Binary->virtualAddrToOffset(LBR.Source);
uint64_t TargetOffset = Binary->virtualAddrToOffset(LBR.Target);
// Record the branch if its sourceOffset is external. It can be the case an
// external source call an internal function, later this branch will be used
// to generate the function's head sample.
if (Binary->offsetIsCode(TargetOffset)) {
Counter.recordBranchCount(SourceOffset, TargetOffset, Repeat);
}
// If this not the first LBR, update the range count between TO of current
// LBR and FROM of next LBR.
uint64_t StartOffset = TargetOffset;
if (Binary->offsetIsCode(StartOffset) && Binary->offsetIsCode(EndOffeset) &&
isValidFallThroughRange(StartOffset, EndOffeset, Binary))
Counter.recordRangeCount(StartOffset, EndOffeset, Repeat);
EndOffeset = SourceOffset;
}
}
void LBRPerfReader::parseSample(TraceStream &TraceIt, uint64_t Count) {
std::shared_ptr<PerfSample> Sample = std::make_shared<PerfSample>();
// Parsing LBR stack and populate into PerfSample.LBRStack
if (extractLBRStack(TraceIt, Sample->LBRStack)) {
warnIfMissingMMap();
// Record LBR only samples by aggregation
AggregatedSamples[Hashable<PerfSample>(Sample)] += Count;
}
}
void PerfScriptReader::generateUnsymbolizedProfile() {
// There is no context for LBR only sample, so initialize one entry with
// fake "empty" context key.
assert(SampleCounters.empty() &&
"Sample counter map should be empty before raw profile generation");
std::shared_ptr<StringBasedCtxKey> Key =
std::make_shared<StringBasedCtxKey>();
SampleCounters.emplace(Hashable<ContextKey>(Key), SampleCounter());
for (const auto &Item : AggregatedSamples) {
const PerfSample *Sample = Item.first.getPtr();
computeCounterFromLBR(Sample, Item.second);
}
}
uint64_t PerfScriptReader::parseAggregatedCount(TraceStream &TraceIt) {
// The aggregated count is optional, so do not skip the line and return 1 if
// it's unmatched
uint64_t Count = 1;
if (!TraceIt.getCurrentLine().getAsInteger(10, Count))
TraceIt.advance();
return Count;
}
void PerfScriptReader::parseSample(TraceStream &TraceIt) {
NumTotalSample++;
uint64_t Count = parseAggregatedCount(TraceIt);
assert(Count >= 1 && "Aggregated count should be >= 1!");
parseSample(TraceIt, Count);
}
bool PerfScriptReader::extractMMap2EventForBinary(ProfiledBinary *Binary,
StringRef Line,
MMapEvent &MMap) {
// 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,
MMAPPED_ADDRESS = 2,
MMAPPED_SIZE = 3,
PAGE_OFFSET = 4,
BINARY_PATH = 5
};
Regex RegMmap2(Pattern);
SmallVector<StringRef, 6> Fields;
bool R = RegMmap2.match(Line, &Fields);
if (!R) {
std::string ErrorMsg = "Cannot parse mmap event: " + Line.str() + " \n";
exitWithError(ErrorMsg);
}
Fields[PID].getAsInteger(10, MMap.PID);
Fields[MMAPPED_ADDRESS].getAsInteger(0, MMap.Address);
Fields[MMAPPED_SIZE].getAsInteger(0, MMap.Size);
Fields[PAGE_OFFSET].getAsInteger(0, MMap.Offset);
MMap.BinaryPath = Fields[BINARY_PATH];
if (ShowMmapEvents) {
outs() << "Mmap: Binary " << MMap.BinaryPath << " loaded at "
<< format("0x%" PRIx64 ":", MMap.Address) << " \n";
}
StringRef BinaryName = llvm::sys::path::filename(MMap.BinaryPath);
return Binary->getName() == BinaryName;
}
void PerfScriptReader::parseMMap2Event(TraceStream &TraceIt) {
MMapEvent MMap;
if (extractMMap2EventForBinary(Binary, TraceIt.getCurrentLine(), MMap))
updateBinaryAddress(MMap);
TraceIt.advance();
}
void PerfScriptReader::parseEventOrSample(TraceStream &TraceIt) {
if (isMMap2Event(TraceIt.getCurrentLine()))
parseMMap2Event(TraceIt);
else
parseSample(TraceIt);
}
void PerfScriptReader::parseAndAggregateTrace() {
// Trace line iterator
TraceStream TraceIt(PerfTraceFile);
while (!TraceIt.isAtEoF())
parseEventOrSample(TraceIt);
}
// A LBR sample is like:
// 40062f 0x5c6313f/0x5c63170/P/-/-/0 0x5c630e7/0x5c63130/P/-/-/0 ...
// A heuristic for fast detection by checking whether a
// leading " 0x" and the '/' exist.
bool PerfScriptReader::isLBRSample(StringRef Line) {
// Skip the leading instruction pointer
SmallVector<StringRef, 32> Records;
Line.trim().split(Records, " ", 2, false);
if (Records.size() < 2)
return false;
if (Records[1].startswith("0x") && Records[1].contains('/'))
return true;
return false;
}
bool PerfScriptReader::isMMap2Event(StringRef Line) {
// Short cut to avoid string find is possible.
if (Line.empty() || Line.size() < 50)
return false;
if (std::isdigit(Line[0]))
return false;
// PERF_RECORD_MMAP2 does not appear at the beginning of the line
// for ` perf script --show-mmap-events -i ...`
return Line.contains("PERF_RECORD_MMAP2");
}
// The raw hybird sample is like
// 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
// Determine the perfscript contains hybrid samples(call stack + LBRs) by
// checking whether there is a non-empty call stack immediately followed by
// a LBR sample
PerfContent PerfScriptReader::checkPerfScriptType(StringRef FileName) {
TraceStream TraceIt(FileName);
uint64_t FrameAddr = 0;
while (!TraceIt.isAtEoF()) {
// Skip the aggregated count
if (!TraceIt.getCurrentLine().getAsInteger(10, FrameAddr))
TraceIt.advance();
// Detect sample with call stack
int32_t Count = 0;
while (!TraceIt.isAtEoF() &&
!TraceIt.getCurrentLine().ltrim().getAsInteger(16, FrameAddr)) {
Count++;
TraceIt.advance();
}
if (!TraceIt.isAtEoF()) {
if (isLBRSample(TraceIt.getCurrentLine())) {
if (Count > 0)
return PerfContent::LBRStack;
else
return PerfContent::LBR;
}
TraceIt.advance();
}
}
exitWithError("Invalid perf script input!");
return PerfContent::UnknownContent;
}
void HybridPerfReader::generateUnsymbolizedProfile() {
ProfileIsCS = !IgnoreStackSamples;
if (ProfileIsCS)
unwindSamples();
else
PerfScriptReader::generateUnsymbolizedProfile();
}
void PerfScriptReader::warnTruncatedStack() {
if (ShowDetailedWarning) {
for (auto Address : InvalidReturnAddresses) {
WithColor::warning()
<< "Truncated stack sample due to invalid return address at "
<< format("0x%" PRIx64, Address)
<< ", likely caused by frame pointer omission\n";
}
}
emitWarningSummary(
InvalidReturnAddresses.size(), AggregatedSamples.size(),
"of truncated stack samples due to invalid return address, "
"likely caused by frame pointer omission.");
}
void PerfScriptReader::warnInvalidRange() {
std::unordered_map<std::pair<uint64_t, uint64_t>, uint64_t,
pair_hash<uint64_t, uint64_t>>
Ranges;
for (const auto &Item : AggregatedSamples) {
const PerfSample *Sample = Item.first.getPtr();
uint64_t Count = Item.second;
uint64_t EndOffeset = 0;
for (const LBREntry &LBR : Sample->LBRStack) {
uint64_t SourceOffset = Binary->virtualAddrToOffset(LBR.Source);
uint64_t StartOffset = Binary->virtualAddrToOffset(LBR.Target);
if (EndOffeset != 0)
Ranges[{StartOffset, EndOffeset}] += Count;
EndOffeset = SourceOffset;
}
}
if (Ranges.empty()) {
WithColor::warning() << "No samples in perf script!\n";
return;
}
auto WarnInvalidRange =
[&](uint64_t StartOffset, uint64_t EndOffset, StringRef Msg) {
if (!ShowDetailedWarning)
return;
WithColor::warning()
<< "["
<< format("%8" PRIx64, Binary->offsetToVirtualAddr(StartOffset))
<< ","
<< format("%8" PRIx64, Binary->offsetToVirtualAddr(EndOffset))
<< "]: " << Msg << "\n";
};
const char *EndNotBoundaryMsg = "Range is not on instruction boundary, "
"likely due to profile and binary mismatch.";
const char *DanglingRangeMsg = "Range does not belong to any functions, "
"likely from PLT, .init or .fini section.";
const char *RangeCrossFuncMsg =
"Fall through range should not cross function boundaries, likely due to "
"profile and binary mismatch.";
const char *BogusRangeMsg = "Range start is after or too far from range end.";
uint64_t TotalRangeNum = 0;
uint64_t InstNotBoundary = 0;
uint64_t UnmatchedRange = 0;
uint64_t RangeCrossFunc = 0;
uint64_t BogusRange = 0;
for (auto &I : Ranges) {
uint64_t StartOffset = I.first.first;
uint64_t EndOffset = I.first.second;
TotalRangeNum += I.second;
if (!Binary->offsetIsCode(StartOffset) ||
!Binary->offsetIsTransfer(EndOffset)) {
InstNotBoundary += I.second;
WarnInvalidRange(StartOffset, EndOffset, EndNotBoundaryMsg);
}
auto *FRange = Binary->findFuncRangeForOffset(StartOffset);
if (!FRange) {
UnmatchedRange += I.second;
WarnInvalidRange(StartOffset, EndOffset, DanglingRangeMsg);
continue;
}
if (EndOffset >= FRange->EndOffset) {
RangeCrossFunc += I.second;
WarnInvalidRange(StartOffset, EndOffset, RangeCrossFuncMsg);
}
if (!isValidFallThroughRange(StartOffset, EndOffset, Binary)) {
BogusRange += I.second;
WarnInvalidRange(StartOffset, EndOffset, BogusRangeMsg);
}
}
emitWarningSummary(
InstNotBoundary, TotalRangeNum,
"of samples are from ranges that are not on instruction boundary.");
emitWarningSummary(
UnmatchedRange, TotalRangeNum,
"of samples are from ranges that do not belong to any functions.");
emitWarningSummary(
RangeCrossFunc, TotalRangeNum,
"of samples are from ranges that do cross function boundaries.");
emitWarningSummary(
BogusRange, TotalRangeNum,
"of samples are from ranges that have range start after or too far from "
"range end acrossing the unconditinal jmp.");
}
void PerfScriptReader::parsePerfTraces() {
// Parse perf traces and do aggregation.
parseAndAggregateTrace();
emitWarningSummary(NumLeafExternalFrame, NumTotalSample,
"of samples have leaf external frame in call stack.");
emitWarningSummary(NumLeadingOutgoingLBR, NumTotalSample,
"of samples have leading external LBR.");
// Generate unsymbolized profile.
warnTruncatedStack();
warnInvalidRange();
generateUnsymbolizedProfile();
AggregatedSamples.clear();
if (SkipSymbolization)
writeUnsymbolizedProfile(OutputFilename);
}
} // end namespace sampleprof
} // end namespace llvm
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