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//===-- ProfiledBinary.h - Binary decoder -----------------------*- C++ -*-===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
#include "CallContext.h"
#include "PseudoProbe.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/DebugInfo/Symbolize/Symbolize.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCDisassembler/MCDisassembler.h"
#include "llvm/MC/MCInst.h"
#include "llvm/MC/MCInstPrinter.h"
#include "llvm/MC/MCInstrAnalysis.h"
#include "llvm/MC/MCInstrInfo.h"
#include "llvm/MC/MCObjectFileInfo.h"
#include "llvm/MC/MCRegisterInfo.h"
#include "llvm/MC/MCSubtargetInfo.h"
#include "llvm/MC/MCTargetOptions.h"
#include "llvm/Object/ELFObjectFile.h"
#include "llvm/ProfileData/SampleProf.h"
#include "llvm/Support/Path.h"
#include <list>
#include <set>
#include <sstream>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>
using namespace llvm;
using namespace sampleprof;
using namespace llvm::object;
namespace llvm {
namespace sampleprof {
class ProfiledBinary;
struct InstructionPointer {
ProfiledBinary *Binary;
union {
// Offset of the executable segment of the binary.
uint64_t Offset = 0;
// Also used as address in unwinder
uint64_t Address;
// Index to the sorted code address array of the binary.
uint64_t Index = 0;
InstructionPointer(ProfiledBinary *Binary, uint64_t Address,
bool RoundToNext = false);
void advance();
void backward();
void update(uint64_t Addr);
// PrologEpilog offset tracker, used to filter out broken stack samples
// Currently we use a heuristic size (two) to infer prolog and epilog
// based on the start address and return address. In the future,
// we will switch to Dwarf CFI based tracker
struct PrologEpilogTracker {
// A set of prolog and epilog offsets. Used by virtual unwinding.
std::unordered_set<uint64_t> PrologEpilogSet;
ProfiledBinary *Binary;
PrologEpilogTracker(ProfiledBinary *Bin) : Binary(Bin){};
// Take the two addresses from the start of function as prolog
void inferPrologOffsets(
std::unordered_map<uint64_t, std::string> &FuncStartAddrMap) {
for (auto I : FuncStartAddrMap) {
InstructionPointer IP(Binary, I.first);
// Take the last two addresses before the return address as epilog
void inferEpilogOffsets(std::unordered_set<uint64_t> &RetAddrs) {
for (auto Addr : RetAddrs) {
InstructionPointer IP(Binary, Addr);
class ProfiledBinary {
// Absolute path of the binary.
std::string Path;
// The target triple.
Triple TheTriple;
// The runtime base address that the executable sections are loaded at.
mutable uint64_t BaseAddress = 0;
// The preferred base address that the executable sections are loaded at.
uint64_t PreferredBaseAddress = 0;
// Mutiple MC component info
std::unique_ptr<const MCRegisterInfo> MRI;
std::unique_ptr<const MCAsmInfo> AsmInfo;
std::unique_ptr<const MCSubtargetInfo> STI;
std::unique_ptr<const MCInstrInfo> MII;
std::unique_ptr<MCDisassembler> DisAsm;
std::unique_ptr<const MCInstrAnalysis> MIA;
std::unique_ptr<MCInstPrinter> IPrinter;
// A list of text sections sorted by start RVA and size. Used to check
// if a given RVA is a valid code address.
std::set<std::pair<uint64_t, uint64_t>> TextSections;
// Function offset to name mapping.
std::unordered_map<uint64_t, std::string> FuncStartAddrMap;
// Offset to context location map. Used to expand the context.
std::unordered_map<uint64_t, FrameLocationStack> Offset2LocStackMap;
// An array of offsets of all instructions sorted in increasing order. The
// sorting is needed to fast advance to the next forward/backward instruction.
std::vector<uint64_t> CodeAddrs;
// A set of call instruction offsets. Used by virtual unwinding.
std::unordered_set<uint64_t> CallAddrs;
// A set of return instruction offsets. Used by virtual unwinding.
std::unordered_set<uint64_t> RetAddrs;
PrologEpilogTracker ProEpilogTracker;
// The symbolizer used to get inline context for an instruction.
std::unique_ptr<symbolize::LLVMSymbolizer> Symbolizer;
// Pseudo probe decoder
PseudoProbeDecoder ProbeDecoder;
bool UsePseudoProbes = false;
void setPreferredBaseAddress(const ELFObjectFileBase *O);
void decodePseudoProbe(const ELFObjectFileBase *Obj);
// Set up disassembler and related components.
void setUpDisassembler(const ELFObjectFileBase *Obj);
void setupSymbolizer();
/// Dissassemble the text section and build various address maps.
void disassemble(const ELFObjectFileBase *O);
/// Helper function to dissassemble the symbol and extract info for unwinding
bool dissassembleSymbol(std::size_t SI, ArrayRef<uint8_t> Bytes,
SectionSymbolsTy &Symbols, const SectionRef &Section);
/// Symbolize a given instruction pointer and return a full call context.
FrameLocationStack symbolize(const InstructionPointer &IP,
bool UseCanonicalFnName = false);
/// Decode the interesting parts of the binary and build internal data
/// structures. On high level, the parts of interest are:
/// 1. Text sections, including the main code section and the PLT
/// entries that will be used to handle cross-module call transitions.
/// 2. The .debug_line section, used by Dwarf-based profile generation.
/// 3. Pseudo probe related sections, used by probe-based profile
/// generation.
void load();
const FrameLocationStack &getFrameLocationStack(uint64_t Offset) const {
auto I = Offset2LocStackMap.find(Offset);
assert(I != Offset2LocStackMap.end() &&
"Can't find location for offset in the binary");
return I->second;
ProfiledBinary(StringRef Path) : Path(Path), ProEpilogTracker(this) {
uint64_t virtualAddrToOffset(uint64_t VitualAddress) const {
return VitualAddress - BaseAddress;
uint64_t offsetToVirtualAddr(uint64_t Offset) const {
return Offset + BaseAddress;
StringRef getPath() const { return Path; }
StringRef getName() const { return llvm::sys::path::filename(Path); }
uint64_t getBaseAddress() const { return BaseAddress; }
void setBaseAddress(uint64_t Address) { BaseAddress = Address; }
uint64_t getPreferredBaseAddress() const { return PreferredBaseAddress; }
bool addressIsCode(uint64_t Address) const {
uint64_t Offset = virtualAddrToOffset(Address);
return Offset2LocStackMap.find(Offset) != Offset2LocStackMap.end();
bool addressIsCall(uint64_t Address) const {
uint64_t Offset = virtualAddrToOffset(Address);
return CallAddrs.count(Offset);
bool addressIsReturn(uint64_t Address) const {
uint64_t Offset = virtualAddrToOffset(Address);
return RetAddrs.count(Offset);
bool addressInPrologEpilog(uint64_t Address) const {
uint64_t Offset = virtualAddrToOffset(Address);
return ProEpilogTracker.PrologEpilogSet.count(Offset);
uint64_t getAddressforIndex(uint64_t Index) const {
return offsetToVirtualAddr(CodeAddrs[Index]);
bool usePseudoProbes() const { return UsePseudoProbes; }
// Get the index in CodeAddrs for the address
// As we might get an address which is not the code
// here it would round to the next valid code address by
// using lower bound operation
uint32_t getIndexForAddr(uint64_t Address) const {
uint64_t Offset = virtualAddrToOffset(Address);
auto Low = llvm::lower_bound(CodeAddrs, Offset);
return Low - CodeAddrs.begin();
uint64_t getCallAddrFromFrameAddr(uint64_t FrameAddr) const {
return getAddressforIndex(getIndexForAddr(FrameAddr) - 1);
StringRef getFuncFromStartOffset(uint64_t Offset) {
return FuncStartAddrMap[Offset];
Optional<FrameLocation> getInlineLeafFrameLoc(uint64_t Offset) {
const auto &Stack = getFrameLocationStack(Offset);
if (Stack.empty())
return {};
return Stack.back();
// Compare two addresses' inline context
bool inlineContextEqual(uint64_t Add1, uint64_t Add2) const;
// Get the context string of the current stack with inline context filled in.
// It will search the disassembling info stored in Offset2LocStackMap. This is
// used as the key of function sample map
getExpandedContextStr(const SmallVectorImpl<uint64_t> &Stack) const;
const PseudoProbe *getCallProbeForAddr(uint64_t Address) const {
return ProbeDecoder.getCallProbeForAddr(Address);
getInlineContextForProbe(const PseudoProbe *Probe,
SmallVectorImpl<std::string> &InlineContextStack,
bool IncludeLeaf = false) const {
return ProbeDecoder.getInlineContextForProbe(Probe, InlineContextStack,
const AddressProbesMap &getAddress2ProbesMap() const {
return ProbeDecoder.getAddress2ProbesMap();
const PseudoProbeFuncDesc *getFuncDescForGUID(uint64_t GUID) {
return ProbeDecoder.getFuncDescForGUID(GUID);
const PseudoProbeFuncDesc *getInlinerDescForProbe(const PseudoProbe *Probe) {
return ProbeDecoder.getInlinerDescForProbe(Probe);
} // end namespace sampleprof
} // end namespace llvm