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d15b93badec2ffdfc6e5a01b9386cdefb4ea59ac
clang-p2996/bolt/BinaryFunction.cpp
Maksim Panchenko d15b93bade [BOLT] Major overhaul of profiling in BOLT 
Summary:
Profile reading was tightly coupled with building CFG. Since I plan
to move to a new profile format that will be associated with CFG
it is critical to decouple the two phases.

We now have read profile right after the cfg was constructed, but
before it is "canonicalized", i.e. CTCs will till be there.

After reading the profile, we do a post-processing pass that fixes
CFG and does some post-processing for debug info, such as
inference of fall-throughs, which is still required with the current
format.

Another good reason for decoupling is that we can use profile with
CFG to more accurately record fall-through branches during
aggregation.

At the moment we use "Offset" annotations to facilitate location
of instructions corresponding to the profile. This might not be
super efficient. However, once we switch to the new profile format
the offsets would be no longer needed. We might keep them for
the aggregator, but if we have to trust LBR data that might
not be strictly necessary.

I've tried to make changes while keeping backwards compatibly. This makes
it easier to verify correctness of the changes, but that also means
that we lose accuracy of the profile.

Some refactoring is included.

Flag "-prof-compat-mode" (on by default) is used for bug-level
backwards compatibility. Disable it for more accurate tracing.

(cherry picked from FBD6506156)
2017-11-28 09:57:21 -08:00

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//===--- BinaryFunction.cpp - Interface for machine-level function --------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
//===----------------------------------------------------------------------===//
#include "BinaryBasicBlock.h"
#include "BinaryFunction.h"
#include "DataReader.h"
#include "llvm/ADT/edit_distance.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/DebugInfo/DWARF/DWARFContext.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCInst.h"
#include "llvm/MC/MCInstPrinter.h"
#include "llvm/MC/MCSection.h"
#include "llvm/MC/MCSectionELF.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/Object/ObjectFile.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/GraphWriter.h"
#include "llvm/Support/Timer.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Support/Regex.h"
#include <limits>
#include <queue>
#include <string>
#include <functional>
#undef DEBUG_TYPE
#define DEBUG_TYPE "bolt"
using namespace llvm;
using namespace bolt;
namespace opts {
extern cl::OptionCategory BoltCategory;
extern cl::OptionCategory BoltOptCategory;
extern cl::OptionCategory BoltRelocCategory;
extern bool shouldProcess(const BinaryFunction &);
extern cl::opt<bool> UpdateDebugSections;
extern cl::opt<unsigned> Verbosity;
static cl::opt<bool>
AlignBlocks("align-blocks",
cl::desc("try to align BBs inserting nops"),
cl::ZeroOrMore,
cl::cat(BoltOptCategory));
static cl::opt<bool>
DotToolTipCode("dot-tooltip-code",
cl::desc("add basic block instructions as tool tips on nodes"),
cl::ZeroOrMore,
cl::Hidden,
cl::cat(BoltCategory));
static cl::opt<uint32_t>
DynoStatsScale("dyno-stats-scale",
cl::desc("scale to be applied while reporting dyno stats"),
cl::Optional,
cl::init(1),
cl::Hidden,
cl::cat(BoltCategory));
cl::opt<JumpTableSupportLevel>
JumpTables("jump-tables",
cl::desc("jump tables support (default=basic)"),
cl::init(JTS_BASIC),
cl::values(
clEnumValN(JTS_NONE, "none",
"do not optimize functions with jump tables"),
clEnumValN(JTS_BASIC, "basic",
"optimize functions with jump tables"),
clEnumValN(JTS_MOVE, "move",
"move jump tables to a separate section"),
clEnumValN(JTS_SPLIT, "split",
"split jump tables section into hot and cold based on "
"function execution frequency"),
clEnumValN(JTS_AGGRESSIVE, "aggressive",
"aggressively split jump tables section based on usage "
"of the tables"),
clEnumValEnd),
cl::ZeroOrMore,
cl::cat(BoltOptCategory));
cl::opt<bool>
PrintDynoStats("dyno-stats",
cl::desc("print execution info based on profile"),
cl::cat(BoltCategory));
static cl::opt<bool>
PrintDynoStatsOnly("print-dyno-stats-only",
cl::desc("while printing functions output dyno-stats and skip instructions"),
cl::init(false),
cl::Hidden,
cl::cat(BoltCategory));
static cl::opt<bool>
PrintJumpTables("print-jump-tables",
cl::desc("print jump tables"),
cl::ZeroOrMore,
cl::Hidden,
cl::cat(BoltCategory));
static cl::list<std::string>
PrintOnly("print-only",
cl::CommaSeparated,
cl::desc("list of functions to print"),
cl::value_desc("func1,func2,func3,..."),
cl::Hidden,
cl::cat(BoltCategory));
static cl::list<std::string>
PrintOnlyRegex("print-only-regex",
cl::CommaSeparated,
cl::desc("list of function regexes to print"),
cl::value_desc("func1,func2,func3,..."),
cl::Hidden,
cl::cat(BoltCategory));
cl::opt<bool>
TimeBuild("time-build",
cl::desc("print time spent constructing binary functions"),
cl::ZeroOrMore,
cl::Hidden,
cl::cat(BoltCategory));
bool shouldPrint(const BinaryFunction &Function) {
if (PrintOnly.empty() && PrintOnlyRegex.empty())
return true;
for (auto &Name : opts::PrintOnly) {
if (Function.hasName(Name)) {
return true;
}
}
for (auto &Name : opts::PrintOnlyRegex) {
if (Function.hasNameRegex(Name)) {
return true;
}
}
return false;
}
} // namespace opts
namespace llvm {
namespace bolt {
constexpr const char *DynoStats::Desc[];
constexpr unsigned BinaryFunction::MinAlign;
const char BinaryFunction::TimerGroupName[] = "Build binary functions";
namespace {
template <typename R>
bool emptyRange(const R &Range) {
return Range.begin() == Range.end();
}
/// Gets debug line information for the instruction located at the given
/// address in the original binary. The SMLoc's pointer is used
/// to point to this information, which is represented by a
/// DebugLineTableRowRef. The returned pointer is null if no debug line
/// information for this instruction was found.
SMLoc findDebugLineInformationForInstructionAt(
uint64_t Address,
DWARFUnitLineTable &ULT) {
// We use the pointer in SMLoc to store an instance of DebugLineTableRowRef,
// which occupies 64 bits. Thus, we can only proceed if the struct fits into
// the pointer itself.
assert(
sizeof(decltype(SMLoc().getPointer())) >= sizeof(DebugLineTableRowRef) &&
"Cannot fit instruction debug line information into SMLoc's pointer");
SMLoc NullResult = DebugLineTableRowRef::NULL_ROW.toSMLoc();
auto &LineTable = ULT.second;
if (!LineTable)
return NullResult;
uint32_t RowIndex = LineTable->lookupAddress(Address);
if (RowIndex == LineTable->UnknownRowIndex)
return NullResult;
assert(RowIndex < LineTable->Rows.size() &&
"Line Table lookup returned invalid index.");
decltype(SMLoc().getPointer()) Ptr;
DebugLineTableRowRef *InstructionLocation =
reinterpret_cast<DebugLineTableRowRef *>(&Ptr);
InstructionLocation->DwCompileUnitIndex = ULT.first->getOffset();
InstructionLocation->RowIndex = RowIndex + 1;
return SMLoc::getFromPointer(Ptr);
}
} // namespace
bool DynoStats::operator<(const DynoStats &Other) const {
return std::lexicographical_compare(
&Stats[FIRST_DYNO_STAT], &Stats[LAST_DYNO_STAT],
&Other.Stats[FIRST_DYNO_STAT], &Other.Stats[LAST_DYNO_STAT]
);
}
bool DynoStats::operator==(const DynoStats &Other) const {
return std::equal(
&Stats[FIRST_DYNO_STAT], &Stats[LAST_DYNO_STAT],
&Other.Stats[FIRST_DYNO_STAT]
);
}
bool DynoStats::lessThan(const DynoStats &Other,
ArrayRef<Category> Keys) const {
return std::lexicographical_compare(
Keys.begin(), Keys.end(),
Keys.begin(), Keys.end(),
[this,&Other](const Category A, const Category) {
return Stats[A] < Other.Stats[A];
}
);
}
uint64_t BinaryFunction::Count = 0;
bool BinaryFunction::hasNameRegex(const std::string &NameRegex) const {
Regex MatchName(NameRegex);
for (auto &Name : Names)
if (MatchName.match(Name))
return true;
return false;
}
BinaryBasicBlock *
BinaryFunction::getBasicBlockContainingOffset(uint64_t Offset) {
if (Offset > Size)
return nullptr;
if (BasicBlockOffsets.empty())
return nullptr;
/*
* This is commented out because it makes BOLT too slow.
* assert(std::is_sorted(BasicBlockOffsets.begin(),
* BasicBlockOffsets.end(),
* CompareBasicBlockOffsets())));
*/
auto I = std::upper_bound(BasicBlockOffsets.begin(),
BasicBlockOffsets.end(),
BasicBlockOffset(Offset, nullptr),
CompareBasicBlockOffsets());
assert(I != BasicBlockOffsets.begin() && "first basic block not at offset 0");
--I;
auto *BB = I->second;
return (Offset < BB->getOffset() + BB->getOriginalSize()) ? BB : nullptr;
}
void BinaryFunction::markUnreachable() {
std::stack<BinaryBasicBlock *> Stack;
for (auto *BB : layout()) {
BB->markValid(false);
}
// Add all entries and landing pads as roots.
for (auto *BB : BasicBlocks) {
if (BB->isEntryPoint() || BB->isLandingPad()) {
Stack.push(BB);
BB->markValid(true);
}
}
// Determine reachable BBs from the entry point
while (!Stack.empty()) {
auto BB = Stack.top();
Stack.pop();
for (auto Succ : BB->successors()) {
if (Succ->isValid())
continue;
Succ->markValid(true);
Stack.push(Succ);
}
}
}
// Any unnecessary fallthrough jumps revealed after calling eraseInvalidBBs
// will be cleaned up by fixBranches().
std::pair<unsigned, uint64_t> BinaryFunction::eraseInvalidBBs() {
BasicBlockOrderType NewLayout;
unsigned Count = 0;
uint64_t Bytes = 0;
for (auto *BB : layout()) {
assert((!BB->isEntryPoint() || BB->isValid()) &&
"all entry blocks must be valid");
if (BB->isValid()) {
NewLayout.push_back(BB);
} else {
++Count;
Bytes += BC.computeCodeSize(BB->begin(), BB->end());
}
}
BasicBlocksLayout = std::move(NewLayout);
BasicBlockListType NewBasicBlocks;
for (auto I = BasicBlocks.begin(), E = BasicBlocks.end(); I != E; ++I) {
if ((*I)->isValid()) {
NewBasicBlocks.push_back(*I);
} else {
DeletedBasicBlocks.push_back(*I);
}
}
BasicBlocks = std::move(NewBasicBlocks);
assert(BasicBlocks.size() == BasicBlocksLayout.size());
// Update CFG state if needed
if (Count > 0)
recomputeLandingPads();
return std::make_pair(Count, Bytes);
}
bool BinaryFunction::isForwardCall(const MCSymbol *CalleeSymbol) const {
// This function should work properly before and after function reordering.
// In order to accomplish this, we use the function index (if it is valid).
// If the function indices are not valid, we fall back to the original
// addresses. This should be ok because the functions without valid indices
// should have been ordered with a stable sort.
const auto *CalleeBF = BC.getFunctionForSymbol(CalleeSymbol);
if (CalleeBF) {
if (hasValidIndex() && CalleeBF->hasValidIndex()) {
return getIndex() < CalleeBF->getIndex();
} else if (hasValidIndex() && !CalleeBF->hasValidIndex()) {
return true;
} else if (!hasValidIndex() && CalleeBF->hasValidIndex()) {
return false;
} else {
return getAddress() < CalleeBF->getAddress();
}
} else {
// Absolute symbol.
auto const CalleeSI = BC.GlobalSymbols.find(CalleeSymbol->getName());
assert(CalleeSI != BC.GlobalSymbols.end() && "unregistered symbol found");
return CalleeSI->second > getAddress();
}
}
void BinaryFunction::dump(bool PrintInstructions) const {
print(dbgs(), "", PrintInstructions);
}
void BinaryFunction::print(raw_ostream &OS, std::string Annotation,
bool PrintInstructions) const {
// FIXME: remove after #15075512 is done.
if (!opts::shouldProcess(*this) || !opts::shouldPrint(*this))
return;
StringRef SectionName;
Section.getName(SectionName);
OS << "Binary Function \"" << *this << "\" " << Annotation << " {";
if (Names.size() > 1) {
OS << "\n Other names : ";
auto Sep = "";
for (unsigned i = 0; i < Names.size() - 1; ++i) {
OS << Sep << Names[i];
Sep = "\n ";
}
}
OS << "\n Number : " << FunctionNumber
<< "\n State : " << CurrentState
<< "\n Address : 0x" << Twine::utohexstr(Address)
<< "\n Size : 0x" << Twine::utohexstr(Size)
<< "\n MaxSize : 0x" << Twine::utohexstr(MaxSize)
<< "\n Offset : 0x" << Twine::utohexstr(FileOffset)
<< "\n Section : " << SectionName
<< "\n Orc Section : " << getCodeSectionName()
<< "\n LSDA : 0x" << Twine::utohexstr(getLSDAAddress())
<< "\n IsSimple : " << IsSimple
<< "\n IsSplit : " << isSplit()
<< "\n BB Count : " << size();
if (hasCFG()) {
OS << "\n Hash : " << Twine::utohexstr(hash());
}
if (FrameInstructions.size()) {
OS << "\n CFI Instrs : " << FrameInstructions.size();
}
if (BasicBlocksLayout.size()) {
OS << "\n BB Layout : ";
auto Sep = "";
for (auto BB : BasicBlocksLayout) {
OS << Sep << BB->getName();
Sep = ", ";
}
}
if (ImageAddress)
OS << "\n Image : 0x" << Twine::utohexstr(ImageAddress);
if (ExecutionCount != COUNT_NO_PROFILE) {
OS << "\n Exec Count : " << ExecutionCount;
OS << "\n Profile Acc : " << format("%.1f%%", ProfileMatchRatio * 100.0f);
}
if (opts::PrintDynoStats && !BasicBlocksLayout.empty()) {
OS << '\n';
DynoStats dynoStats = getDynoStats();
OS << dynoStats;
}
OS << "\n}\n";
if (opts::PrintDynoStatsOnly || !PrintInstructions || !BC.InstPrinter)
return;
// Offset of the instruction in function.
uint64_t Offset{0};
if (BasicBlocks.empty() && !Instructions.empty()) {
// Print before CFG was built.
for (const auto &II : Instructions) {
Offset = II.first;
// Print label if exists at this offset.
auto LI = Labels.find(Offset);
if (LI != Labels.end())
OS << LI->second->getName() << ":\n";
BC.printInstruction(OS, II.second, Offset, this);
}
}
for (uint32_t I = 0, E = BasicBlocksLayout.size(); I != E; ++I) {
auto BB = BasicBlocksLayout[I];
if (I != 0 &&
BB->isCold() != BasicBlocksLayout[I - 1]->isCold())
OS << "------- HOT-COLD SPLIT POINT -------\n\n";
OS << BB->getName() << " ("
<< BB->size() << " instructions, align : " << BB->getAlignment()
<< ")\n";
if (BB->isEntryPoint())
OS << " Entry Point\n";
if (BB->isLandingPad())
OS << " Landing Pad\n";
uint64_t BBExecCount = BB->getExecutionCount();
if (hasValidProfile()) {
OS << " Exec Count : " << BBExecCount << '\n';
}
if (BB->getCFIState() >= 0) {
OS << " CFI State : " << BB->getCFIState() << '\n';
}
if (!BB->pred_empty()) {
OS << " Predecessors: ";
auto Sep = "";
for (auto Pred : BB->predecessors()) {
OS << Sep << Pred->getName();
Sep = ", ";
}
OS << '\n';
}
if (!BB->throw_empty()) {
OS << " Throwers: ";
auto Sep = "";
for (auto Throw : BB->throwers()) {
OS << Sep << Throw->getName();
Sep = ", ";
}
OS << '\n';
}
Offset = RoundUpToAlignment(Offset, BB->getAlignment());
// Note: offsets are imprecise since this is happening prior to relaxation.
Offset = BC.printInstructions(OS, BB->begin(), BB->end(), Offset, this);
if (!BB->succ_empty()) {
OS << " Successors: ";
auto BI = BB->branch_info_begin();
auto Sep = "";
for (auto Succ : BB->successors()) {
assert(BI != BB->branch_info_end() && "missing BranchInfo entry");
OS << Sep << Succ->getName();
if (ExecutionCount != COUNT_NO_PROFILE &&
BI->MispredictedCount != BinaryBasicBlock::COUNT_INFERRED) {
OS << " (mispreds: " << BI->MispredictedCount
<< ", count: " << BI->Count << ")";
} else if (ExecutionCount != COUNT_NO_PROFILE &&
BI->Count != BinaryBasicBlock::COUNT_NO_PROFILE) {
OS << " (inferred count: " << BI->Count << ")";
}
Sep = ", ";
++BI;
}
OS << '\n';
}
if (!BB->lp_empty()) {
OS << " Landing Pads: ";
auto Sep = "";
for (auto LP : BB->landing_pads()) {
OS << Sep << LP->getName();
if (ExecutionCount != COUNT_NO_PROFILE) {
OS << " (count: " << LP->getExecutionCount() << ")";
}
Sep = ", ";
}
OS << '\n';
}
// In CFG_Finalized state we can miscalculate CFI state at exit.
if (CurrentState == State::CFG) {
const auto CFIStateAtExit = BB->getCFIStateAtExit();
if (CFIStateAtExit >= 0)
OS << " CFI State: " << CFIStateAtExit << '\n';
}
OS << '\n';
}
// Dump new exception ranges for the function.
if (!CallSites.empty()) {
OS << "EH table:\n";
for (auto &CSI : CallSites) {
OS << " [" << *CSI.Start << ", " << *CSI.End << ") landing pad : ";
if (CSI.LP)
OS << *CSI.LP;
else
OS << "0";
OS << ", action : " << CSI.Action << '\n';
}
OS << '\n';
}
// Print all jump tables.
for (auto &JTI : JumpTables) {
JTI.second.print(OS);
}
OS << "DWARF CFI Instructions:\n";
if (OffsetToCFI.size()) {
// Pre-buildCFG information
for (auto &Elmt : OffsetToCFI) {
OS << format(" %08x:\t", Elmt.first);
assert(Elmt.second < FrameInstructions.size() && "Incorrect CFI offset");
BinaryContext::printCFI(OS, FrameInstructions[Elmt.second]);
OS << "\n";
}
} else {
// Post-buildCFG information
for (uint32_t I = 0, E = FrameInstructions.size(); I != E; ++I) {
const MCCFIInstruction &CFI = FrameInstructions[I];
OS << format(" %d:\t", I);
BinaryContext::printCFI(OS, CFI);
OS << "\n";
}
}
if (FrameInstructions.empty())
OS << " <empty>\n";
OS << "End of Function \"" << *this << "\"\n\n";
}
void BinaryFunction::printRelocations(raw_ostream &OS,
uint64_t Offset,
uint64_t Size) const {
const char* Sep = " # Relocs: ";
auto RI = Relocations.lower_bound(Offset);
while (RI != Relocations.end() && RI->first < Offset + Size) {
OS << Sep << "(R: " << RI->second << ")";
Sep = ", ";
++RI;
}
RI = MoveRelocations.lower_bound(Offset);
while (RI != MoveRelocations.end() && RI->first < Offset + Size) {
OS << Sep << "(M: " << RI->second << ")";
Sep = ", ";
++RI;
}
auto PI = PCRelativeRelocationOffsets.lower_bound(Offset);
if (PI != PCRelativeRelocationOffsets.end() && *PI < Offset + Size) {
OS << Sep << "(pcrel)";
}
}
IndirectBranchType BinaryFunction::processIndirectBranch(MCInst &Instruction,
unsigned Size,
uint64_t Offset) {
const auto PtrSize = BC.AsmInfo->getPointerSize();
// An instruction referencing memory used by jump instruction (directly or
// via register). This location could be an array of function pointers
// in case of indirect tail call, or a jump table.
MCInst *MemLocInstr;
// Address of the table referenced by MemLocInstr. Could be either an
// array of function pointers, or a jump table.
uint64_t ArrayStart = 0;
unsigned BaseRegNum, IndexRegNum;
int64_t DispValue;
const MCExpr *DispExpr;
// In AArch, identify the instruction adding the PC-relative offset to
// jump table entries to correctly decode it.
MCInst *PCRelBaseInstr;
uint64_t PCRelAddr = 0;
auto Begin = Instructions.begin();
auto End = Instructions.end();
if (BC.TheTriple->getArch() == llvm::Triple::aarch64) {
PreserveNops = BC.HasRelocations;
// Start at the last label as an approximation of the current basic block.
// This is a heuristic, since the full set of labels have yet to be
// determined
for (auto LI = Labels.rbegin(); LI != Labels.rend(); ++LI) {
auto II = Instructions.find(LI->first);
if (II != Instructions.end()) {
Begin = II;
break;
}
}
}
auto Type = BC.MIA->analyzeIndirectBranch(Instruction,
Begin,
End,
PtrSize,
MemLocInstr,
BaseRegNum,
IndexRegNum,
DispValue,
DispExpr,
PCRelBaseInstr);
if (Type == IndirectBranchType::UNKNOWN && !MemLocInstr)
return Type;
if (MemLocInstr != &Instruction)
IndexRegNum = 0;
if (BC.TheTriple->getArch() == llvm::Triple::aarch64) {
const auto *Sym = BC.MIA->getTargetSymbol(*PCRelBaseInstr, 1);
assert (Sym && "Symbol extraction failed");
auto SI = BC.GlobalSymbols.find(Sym->getName());
if (SI != BC.GlobalSymbols.end()) {
PCRelAddr = SI->second;
} else {
for (auto &Elmt : Labels) {
if (Elmt.second == Sym) {
PCRelAddr = Elmt.first + getAddress();
break;
}
}
}
uint64_t InstrAddr = 0;
for (auto II = Instructions.rbegin(); II != Instructions.rend(); ++II) {
if (&II->second == PCRelBaseInstr) {
InstrAddr = II->first + getAddress();
break;
}
}
assert(InstrAddr != 0 && "instruction not found");
// We do this to avoid spurious references to code locations outside this
// function (for example, if the indirect jump lives in the last basic
// block of the function, it will create a reference to the next function).
// This replaces a symbol reference with an immediate.
BC.MIA->replaceMemOperandDisp(*PCRelBaseInstr,
MCOperand::createImm(PCRelAddr - InstrAddr));
// FIXME: Disable full jump table processing for AArch64 until we have a
// proper way of determining the jump table limits.
return IndirectBranchType::UNKNOWN;
}
// RIP-relative addressing should be converted to symbol form by now
// in processed instructions (but not in jump).
if (DispExpr) {
auto SI =
BC.GlobalSymbols.find(BC.MIA->getTargetSymbol(DispExpr)->getName());
assert(SI != BC.GlobalSymbols.end() && "global symbol needs a value");
ArrayStart = SI->second;
BaseRegNum = 0;
if (BC.TheTriple->getArch() == llvm::Triple::aarch64) {
ArrayStart &= ~0xFFFULL;
ArrayStart += DispValue & 0xFFFULL;
}
} else {
ArrayStart = static_cast<uint64_t>(DispValue);
}
if (BaseRegNum == BC.MRI->getProgramCounter())
ArrayStart += getAddress() + Offset + Size;
DEBUG(dbgs() << "BOLT-DEBUG: addressed memory is 0x"
<< Twine::utohexstr(ArrayStart) << '\n');
// Check if there's already a jump table registered at this address.
if (auto *JT = getJumpTableContainingAddress(ArrayStart)) {
auto JTOffset = ArrayStart - JT->Address;
if (Type == IndirectBranchType::POSSIBLE_PIC_JUMP_TABLE && JTOffset != 0) {
// Adjust the size of this jump table and create a new one if necessary.
// We cannot re-use the entries since the offsets are relative to the
// table start.
DEBUG(dbgs() << "BOLT-DEBUG: adjusting size of jump table at 0x"
<< Twine::utohexstr(JT->Address) << '\n');
JT->OffsetEntries.resize(JTOffset / JT->EntrySize);
} else {
// Re-use an existing jump table. Perhaps parts of it.
if (Type != IndirectBranchType::POSSIBLE_PIC_JUMP_TABLE) {
assert(JT->Type == JumpTable::JTT_NORMAL &&
"normal jump table expected");
Type = IndirectBranchType::POSSIBLE_JUMP_TABLE;
} else {
assert(JT->Type == JumpTable::JTT_PIC && "PIC jump table expected");
}
// Get or create a new label for the table.
auto LI = JT->Labels.find(JTOffset);
if (LI == JT->Labels.end()) {
auto *JTStartLabel = BC.getOrCreateGlobalSymbol(ArrayStart,
"JUMP_TABLEat");
auto Result = JT->Labels.emplace(JTOffset, JTStartLabel);
assert(Result.second && "error adding jump table label");
LI = Result.first;
}
BC.MIA->replaceMemOperandDisp(const_cast<MCInst &>(*MemLocInstr),
LI->second, BC.Ctx.get());
BC.MIA->setJumpTable(BC.Ctx.get(), Instruction, ArrayStart, IndexRegNum);
JTSites.emplace_back(Offset, ArrayStart);
return Type;
}
}
auto SectionOrError = BC.getSectionForAddress(ArrayStart);
if (!SectionOrError) {
// No section - possibly an absolute address. Since we don't allow
// internal function addresses to escape the function scope - we
// consider it a tail call.
if (opts::Verbosity >= 1) {
errs() << "BOLT-WARNING: no section for address 0x"
<< Twine::utohexstr(ArrayStart) << " referenced from function "
<< *this << '\n';
}
return IndirectBranchType::POSSIBLE_TAIL_CALL;
}
auto &Section = *SectionOrError;
if (Section.isVirtual()) {
// The contents are filled at runtime.
return IndirectBranchType::POSSIBLE_TAIL_CALL;
}
// Extract the value at the start of the array.
StringRef SectionContents;
Section.getContents(SectionContents);
const auto EntrySize =
Type == IndirectBranchType::POSSIBLE_PIC_JUMP_TABLE ? 4 : PtrSize;
DataExtractor DE(SectionContents, BC.AsmInfo->isLittleEndian(), EntrySize);
auto ValueOffset = static_cast<uint32_t>(ArrayStart - Section.getAddress());
uint64_t Value = 0;
std::vector<uint64_t> JTOffsetCandidates;
while (ValueOffset <= Section.getSize() - EntrySize) {
DEBUG(dbgs() << "BOLT-DEBUG: indirect jmp at 0x"
<< Twine::utohexstr(getAddress() + Offset)
<< " is referencing address 0x"
<< Twine::utohexstr(Section.getAddress() + ValueOffset));
// Extract the value and increment the offset.
if (BC.TheTriple->getArch() == llvm::Triple::aarch64) {
Value = PCRelAddr + DE.getSigned(&ValueOffset, EntrySize);
} else if (Type == IndirectBranchType::POSSIBLE_PIC_JUMP_TABLE) {
Value = ArrayStart + DE.getSigned(&ValueOffset, 4);
} else {
Value = DE.getAddress(&ValueOffset);
}
DEBUG(dbgs() << ", which contains value "
<< Twine::utohexstr(Value) << '\n');
if (containsAddress(Value) && Value != getAddress()) {
// Is it possible to have a jump table with function start as an entry?
JTOffsetCandidates.push_back(Value - getAddress());
if (Type == IndirectBranchType::UNKNOWN)
Type = IndirectBranchType::POSSIBLE_JUMP_TABLE;
continue;
}
// Potentially a switch table can contain __builtin_unreachable() entry
// pointing just right after the function. In this case we have to check
// another entry. Otherwise the entry is outside of this function scope
// and it's not a switch table.
if (Value == getAddress() + getSize()) {
JTOffsetCandidates.push_back(Value - getAddress());
} else {
break;
}
}
if (Type == IndirectBranchType::POSSIBLE_JUMP_TABLE ||
Type == IndirectBranchType::POSSIBLE_PIC_JUMP_TABLE) {
assert(JTOffsetCandidates.size() > 2 &&
"expected more than 2 jump table entries");
auto *JTStartLabel = BC.getOrCreateGlobalSymbol(ArrayStart, "JUMP_TABLEat");
DEBUG(dbgs() << "BOLT-DEBUG: creating jump table "
<< JTStartLabel->getName()
<< " in function " << *this << " with "
<< JTOffsetCandidates.size() << " entries.\n");
auto JumpTableType =
Type == IndirectBranchType::POSSIBLE_JUMP_TABLE
? JumpTable::JTT_NORMAL
: JumpTable::JTT_PIC;
JumpTables.emplace(ArrayStart, JumpTable{ArrayStart,
EntrySize,
JumpTableType,
std::move(JTOffsetCandidates),
{{0, JTStartLabel}}});
BC.MIA->replaceMemOperandDisp(const_cast<MCInst &>(*MemLocInstr),
JTStartLabel, BC.Ctx.get());
BC.MIA->setJumpTable(BC.Ctx.get(), Instruction, ArrayStart, IndexRegNum);
JTSites.emplace_back(Offset, ArrayStart);
return Type;
}
BC.InterproceduralReferences.insert(Value);
return IndirectBranchType::POSSIBLE_TAIL_CALL;
}
MCSymbol *BinaryFunction::getOrCreateLocalLabel(uint64_t Address,
bool CreatePastEnd) {
MCSymbol *Result;
// Check if there's already a registered label.
auto Offset = Address - getAddress();
if ((Offset == getSize()) && CreatePastEnd)
return getFunctionEndLabel();
// Check if there's a global symbol registered at given address.
// If so - reuse it since we want to keep the symbol value updated.
if (Offset != 0) {
if (auto *Symbol = BC.getGlobalSymbolAtAddress(Address)) {
Labels[Offset] = Symbol;
return Symbol;
}
}
auto LI = Labels.find(Offset);
if (LI == Labels.end()) {
Result = BC.Ctx->createTempSymbol();
Labels[Offset] = Result;
} else {
Result = LI->second;
}
return Result;
}
void BinaryFunction::disassemble(ArrayRef<uint8_t> FunctionData) {
NamedRegionTimer T("disassemble", TimerGroupName, opts::TimeBuild);
assert(FunctionData.size() == getSize() &&
"function size does not match raw data size");
auto &Ctx = BC.Ctx;
auto &MIA = BC.MIA;
DWARFUnitLineTable ULT = getDWARFUnitLineTable();
matchProfileMemData();
// Insert a label at the beginning of the function. This will be our first
// basic block.
Labels[0] = Ctx->createTempSymbol("BB0", false);
addEntryPointAtOffset(0);
auto handlePCRelOperand =
[&](MCInst &Instruction, uint64_t Address, uint64_t Size) {
uint64_t TargetAddress{0};
MCSymbol *TargetSymbol{nullptr};
if (!MIA->evaluateMemOperandTarget(Instruction, TargetAddress, Address,
Size)) {
errs() << "BOLT-ERROR: PC-relative operand can't be evaluated:\n";
BC.InstPrinter->printInst(&Instruction, errs(), "", *BC.STI);
errs() << '\n';
Instruction.dump_pretty(errs(), BC.InstPrinter.get());
errs() << '\n';
return false;
}
if (TargetAddress == 0) {
if (opts::Verbosity >= 1) {
outs() << "BOLT-INFO: PC-relative operand is zero in function "
<< *this << ".\n";
}
}
if (BC.TheTriple->getArch() == llvm::Triple::aarch64 &&
isInConstantIsland(TargetAddress)) {
TargetSymbol = BC.getOrCreateGlobalSymbol(TargetAddress, "ISLANDat");
IslandSymbols[TargetAddress - getAddress()] = TargetSymbol;
}
// Note that the address does not necessarily have to reside inside
// a section, it could be an absolute address too.
auto Section = BC.getSectionForAddress(TargetAddress);
// Assume AArch64's ADRP never references code - it does, but this is fixed
// after reading relocations. ADRP contents now are not really meaningful
// without its supporting relocation.
if (!TargetSymbol && Section && Section->isText() &&
(BC.TheTriple->getArch() != llvm::Triple::aarch64 ||
!BC.MIA->isADRP(Instruction))) {
if (containsAddress(TargetAddress, /*UseMaxSize=*/
BC.TheTriple->getArch() == llvm::Triple::aarch64)) {
if (TargetAddress != getAddress()) {
// The address could potentially escape. Mark it as another entry
// point into the function.
DEBUG(dbgs() << "BOLT-DEBUG: potentially escaped address 0x"
<< Twine::utohexstr(TargetAddress) << " in function "
<< *this << '\n');
TargetSymbol = getOrCreateLocalLabel(TargetAddress);
addEntryPointAtOffset(TargetAddress - getAddress());
}
} else {
BC.InterproceduralReferences.insert(TargetAddress);
}
}
if (!TargetSymbol)
TargetSymbol = BC.getOrCreateGlobalSymbol(TargetAddress, "DATAat");
MIA->replaceMemOperandDisp(
Instruction, MCOperand::createExpr(BC.MIA->getTargetExprFor(
Instruction,
MCSymbolRefExpr::create(
TargetSymbol, MCSymbolRefExpr::VK_None, *BC.Ctx),
*BC.Ctx, 0)));
return true;
};
uint64_t Size = 0; // instruction size
for (uint64_t Offset = 0; Offset < getSize(); Offset += Size) {
MCInst Instruction;
const uint64_t AbsoluteInstrAddr = getAddress() + Offset;
// Check for data inside code and ignore it
if (DataOffsets.find(Offset) != DataOffsets.end()) {
auto Iter = CodeOffsets.upper_bound(Offset);
if (Iter != CodeOffsets.end()) {
Size = *Iter - Offset;
continue;
}
break;
}
if (!BC.DisAsm->getInstruction(Instruction,
Size,
FunctionData.slice(Offset),
AbsoluteInstrAddr,
nulls(),
nulls())) {
// Functions with "soft" boundaries, e.g. coming from assembly source,
// can have 0-byte padding at the end.
bool IsZeroPadding = true;
for (auto I = Offset; I < getSize(); ++I) {
if (FunctionData[I] != 0) {
IsZeroPadding = false;
break;
}
}
if (!IsZeroPadding) {
// Ignore this function. Skip to the next one in non-relocs mode.
errs() << "BOLT-WARNING: unable to disassemble instruction at offset 0x"
<< Twine::utohexstr(Offset) << " (address 0x"
<< Twine::utohexstr(AbsoluteInstrAddr) << ") in function "
<< *this << '\n';
IsSimple = false;
}
break;
}
// Cannot process functions with AVX-512 instructions.
if (MIA->hasEVEXEncoding(Instruction)) {
if (opts::Verbosity >= 1) {
errs() << "BOLT-WARNING: function " << *this << " uses instruction"
" encoded with EVEX (AVX-512) at offset 0x"
<< Twine::utohexstr(Offset) << ". Disassembly could be wrong."
" Skipping further processing.\n";
}
IsSimple = false;
break;
}
// Check if there's a relocation associated with this instruction.
bool UsedReloc{false};
if (!Relocations.empty()) {
auto RI = Relocations.lower_bound(Offset);
if (RI != Relocations.end() && RI->first < Offset + Size) {
const auto &Relocation = RI->second;
DEBUG(dbgs() << "BOLT-DEBUG: replacing immediate with relocation"
" against " << Relocation.Symbol->getName()
<< " in function " << *this
<< " for instruction at offset 0x"
<< Twine::utohexstr(Offset) << '\n');
int64_t Value;
const auto Result = BC.MIA->replaceImmWithSymbol(
Instruction, Relocation.Symbol, Relocation.Addend, Ctx.get(), Value,
Relocation.Type);
(void)Result;
assert(Result && "cannot replace immediate with relocation");
// For aarch, if we replaced an immediate with a symbol from a
// relocation, we mark it so we do not try to further process a
// pc-relative operand. All we need is the symbol.
if (BC.TheTriple->getArch() == llvm::Triple::aarch64)
UsedReloc = true;
// Make sure we replaced the correct immediate (instruction
// can have multiple immediate operands).
assert((BC.TheTriple->getArch() == llvm::Triple::aarch64 ||
static_cast<uint64_t>(Value) == Relocation.Value) &&
"immediate value mismatch in function");
}
}
// Convert instruction to a shorter version that could be relaxed if needed.
MIA->shortenInstruction(Instruction);
if (MIA->isBranch(Instruction) || MIA->isCall(Instruction)) {
uint64_t TargetAddress = 0;
if (MIA->evaluateBranch(Instruction,
AbsoluteInstrAddr,
Size,
TargetAddress)) {
// Check if the target is within the same function. Otherwise it's
// a call, possibly a tail call.
//
// If the target *is* the function address it could be either a branch
// or a recursive call.
bool IsCall = MIA->isCall(Instruction);
const bool IsCondBranch = MIA->isConditionalBranch(Instruction);
MCSymbol *TargetSymbol = nullptr;
if (IsCall && containsAddress(TargetAddress)) {
if (TargetAddress == getAddress()) {
// Recursive call.
TargetSymbol = getSymbol();
} else {
// Possibly an old-style PIC code
errs() << "BOLT-WARNING: internal call detected at 0x"
<< Twine::utohexstr(AbsoluteInstrAddr)
<< " in function " << *this << ". Skipping.\n";
IsSimple = false;
}
}
if (!TargetSymbol) {
// Create either local label or external symbol.
if (containsAddress(TargetAddress)) {
TargetSymbol = getOrCreateLocalLabel(TargetAddress);
} else {
if (TargetAddress == getAddress() + getSize() &&
TargetAddress < getAddress() + getMaxSize()) {
// Result of __builtin_unreachable().
DEBUG(dbgs() << "BOLT-DEBUG: jump past end detected at 0x"
<< Twine::utohexstr(AbsoluteInstrAddr)
<< " in function " << *this
<< " : replacing with nop.\n");
BC.MIA->createNoop(Instruction);
if (IsCondBranch) {
// Register branch offset for profile validation.
IgnoredBranches.emplace_back(Offset, Offset + Size);
}
goto add_instruction;
}
BC.InterproceduralReferences.insert(TargetAddress);
if (opts::Verbosity >= 2 && !IsCall && Size == 2 &&
!BC.HasRelocations) {
errs() << "BOLT-WARNING: relaxed tail call detected at 0x"
<< Twine::utohexstr(AbsoluteInstrAddr)
<< " in function " << *this
<< ". Code size will be increased.\n";
}
assert(!MIA->isTailCall(Instruction) &&
"synthetic tail call instruction found");
// This is a call regardless of the opcode.
// Assign proper opcode for tail calls, so that they could be
// treated as calls.
if (!IsCall) {
if (!MIA->convertJmpToTailCall(Instruction, BC.Ctx.get())) {
assert(IsCondBranch && "unknown tail call instruction");
if (opts::Verbosity >= 2) {
errs() << "BOLT-WARNING: conditional tail call detected in "
<< "function " << *this << " at 0x"
<< Twine::utohexstr(AbsoluteInstrAddr) << ".\n";
}
}
IsCall = true;
}
TargetSymbol = BC.getOrCreateGlobalSymbol(TargetAddress,
"FUNCat");
if (TargetAddress == 0) {
// We actually see calls to address 0 in presence of weak symbols
// originating from libraries. This code is never meant to be
// executed.
if (opts::Verbosity >= 2) {
outs() << "BOLT-INFO: Function " << *this
<< " has a call to address zero.\n";
}
}
if (BC.HasRelocations) {
// Check if we need to create relocation to move this function's
// code without re-assembly.
size_t RelSize = (Size < 5) ? 1 : 4;
auto RelOffset = Offset + Size - RelSize;
if (BC.TheTriple->getArch() == llvm::Triple::aarch64) {
RelSize = 0;
RelOffset = Offset;
}
auto RI = MoveRelocations.find(RelOffset);
if (RI == MoveRelocations.end()) {
uint64_t RelType = (RelSize == 1) ? ELF::R_X86_64_PC8
: ELF::R_X86_64_PC32;
if (BC.TheTriple->getArch() == llvm::Triple::aarch64)
RelType = ELF::R_AARCH64_CALL26;
DEBUG(dbgs() << "BOLT-DEBUG: creating relocation for static"
<< " function call to " << TargetSymbol->getName()
<< " at offset 0x"
<< Twine::utohexstr(RelOffset)
<< " with size " << RelSize
<< " for function " << *this << '\n');
addRelocation(getAddress() + RelOffset, TargetSymbol, RelType,
-RelSize, 0);
}
auto OI = PCRelativeRelocationOffsets.find(RelOffset);
if (OI != PCRelativeRelocationOffsets.end()) {
PCRelativeRelocationOffsets.erase(OI);
}
}
}
}
if (!IsCall) {
// Add taken branch info.
TakenBranches.emplace_back(Offset, TargetAddress - getAddress());
}
BC.MIA->replaceBranchTarget(Instruction, TargetSymbol, &*Ctx);
// Mark CTC.
if (IsCondBranch && IsCall) {
MIA->setConditionalTailCall(Instruction, TargetAddress);
}
} else {
// Could not evaluate branch. Should be an indirect call or an
// indirect branch. Bail out on the latter case.
if (MIA->isIndirectBranch(Instruction)) {
auto Result = processIndirectBranch(Instruction, Size, Offset);
switch (Result) {
default:
llvm_unreachable("unexpected result");
case IndirectBranchType::POSSIBLE_TAIL_CALL:
{
auto Result =
MIA->convertJmpToTailCall(Instruction, BC.Ctx.get());
(void)Result;
assert(Result);
}
break;
case IndirectBranchType::POSSIBLE_JUMP_TABLE:
case IndirectBranchType::POSSIBLE_PIC_JUMP_TABLE:
if (opts::JumpTables == JTS_NONE)
IsSimple = false;
break;
case IndirectBranchType::UNKNOWN:
// Keep processing. We'll do more checks and fixes in
// postProcessIndirectBranches().
break;
};
}
// Indirect call. We only need to fix it if the operand is RIP-relative
if (IsSimple && MIA->hasPCRelOperand(Instruction)) {
if (!handlePCRelOperand(Instruction, AbsoluteInstrAddr, Size)) {
errs() << "BOLT-ERROR: cannot handle PC-relative operand at 0x"
<< Twine::utohexstr(AbsoluteInstrAddr)
<< ". Skipping function " << *this << ".\n";
if (BC.HasRelocations)
exit(1);
IsSimple = false;
}
}
}
} else {
if (MIA->hasPCRelOperand(Instruction) && !UsedReloc) {
if (!handlePCRelOperand(Instruction, AbsoluteInstrAddr, Size)) {
errs() << "BOLT-ERROR: cannot handle PC-relative operand at 0x"
<< Twine::utohexstr(AbsoluteInstrAddr)
<< ". Skipping function " << *this << ".\n";
if (BC.HasRelocations)
exit(1);
IsSimple = false;
}
}
}
add_instruction:
if (ULT.first && ULT.second) {
Instruction.setLoc(
findDebugLineInformationForInstructionAt(AbsoluteInstrAddr, ULT));
}
// Record offset of the instruction for profile matching.
MIA->addAnnotation(Ctx.get(), Instruction, "Offset", Offset);
if (MemData && !emptyRange(MemData->getMemInfoRange(Offset))) {
MIA->addAnnotation(Ctx.get(), Instruction, "MemDataOffset", Offset);
}
addInstruction(Offset, std::move(Instruction));
}
postProcessJumpTables();
updateState(State::Disassembled);
}
void BinaryFunction::postProcessJumpTables() {
// Create labels for all entries.
for (auto &JTI : JumpTables) {
auto &JT = JTI.second;
for (auto Offset : JT.OffsetEntries) {
auto *Label = getOrCreateLocalLabel(getAddress() + Offset,
/*CreatePastEnd*/ true);
JT.Entries.push_back(Label);
}
}
// Add TakenBranches from JumpTables.
//
// We want to do it after initial processing since we don't know jump tables'
// boundaries until we process them all.
for (auto &JTSite : JTSites) {
const auto JTSiteOffset = JTSite.first;
const auto JTAddress = JTSite.second;
const auto *JT = getJumpTableContainingAddress(JTAddress);
assert(JT && "cannot find jump table for address");
auto EntryOffset = JTAddress - JT->Address;
while (EntryOffset < JT->getSize()) {
auto TargetOffset = JT->OffsetEntries[EntryOffset / JT->EntrySize];
if (TargetOffset < getSize())
TakenBranches.emplace_back(JTSiteOffset, TargetOffset);
// Take ownership of jump table relocations.
if (BC.HasRelocations)
BC.removeRelocationAt(JT->Address + EntryOffset);
EntryOffset += JT->EntrySize;
// A label at the next entry means the end of this jump table.
if (JT->Labels.count(EntryOffset))
break;
}
}
// Free memory used by jump table offsets.
for (auto &JTI : JumpTables) {
auto &JT = JTI.second;
clearList(JT.OffsetEntries);
}
// Remove duplicates branches. We can get a bunch of them from jump tables.
// Without doing jump table value profiling we don't have use for extra
// (duplicate) branches.
std::sort(TakenBranches.begin(), TakenBranches.end());
auto NewEnd = std::unique(TakenBranches.begin(), TakenBranches.end());
TakenBranches.erase(NewEnd, TakenBranches.end());
}
bool BinaryFunction::postProcessIndirectBranches() {
for (auto *BB : layout()) {
for (auto &Instr : *BB) {
if (!BC.MIA->isIndirectBranch(Instr))
continue;
// If there's an indirect branch in a single-block function -
// it must be a tail call.
if (layout_size() == 1) {
BC.MIA->convertJmpToTailCall(Instr, BC.Ctx.get());
return true;
}
// Validate the tail call or jump table assumptions.
if (BC.MIA->isTailCall(Instr) || BC.MIA->getJumpTable(Instr)) {
if (BC.MIA->getMemoryOperandNo(Instr) != -1) {
// We have validated memory contents addressed by the jump
// instruction already.
continue;
}
// This is jump on register. Just make sure the register is defined
// in the containing basic block. Other assumptions were checked
// earlier.
assert(Instr.getOperand(0).isReg() && "register operand expected");
const auto R1 = Instr.getOperand(0).getReg();
auto PrevInstr = BB->rbegin();
while (PrevInstr != BB->rend()) {
const auto &PrevInstrDesc = BC.MII->get(PrevInstr->getOpcode());
if (PrevInstrDesc.hasDefOfPhysReg(*PrevInstr, R1, *BC.MRI)) {
break;
}
++PrevInstr;
}
if (PrevInstr == BB->rend()) {
if (opts::Verbosity >= 2) {
outs() << "BOLT-INFO: rejected potential "
<< (BC.MIA->isTailCall(Instr) ? "indirect tail call"
: "jump table")
<< " in function " << *this
<< " because the jump-on register was not defined in "
<< " basic block " << BB->getName() << ".\n";
DEBUG(dbgs() << BC.printInstructions(dbgs(), BB->begin(), BB->end(),
BB->getOffset(), this, true));
}
return false;
}
// In case of PIC jump table we need to do more checks.
if (BC.MIA->isMoveMem2Reg(*PrevInstr))
continue;
assert(BC.MIA->isADD64rr(*PrevInstr) && "add instruction expected");
auto R2 = PrevInstr->getOperand(2).getReg();
// Make sure both regs are set in the same basic block prior to ADD.
bool IsR1Set = false;
bool IsR2Set = false;
while ((++PrevInstr != BB->rend()) && !(IsR1Set && IsR2Set)) {
const auto &PrevInstrDesc = BC.MII->get(PrevInstr->getOpcode());
if (PrevInstrDesc.hasDefOfPhysReg(*PrevInstr, R1, *BC.MRI))
IsR1Set = true;
else if (PrevInstrDesc.hasDefOfPhysReg(*PrevInstr, R2, *BC.MRI))
IsR2Set = true;
}
if (!IsR1Set || !IsR2Set)
return false;
continue;
}
// If this block contains an epilogue code and has an indirect branch,
// then most likely it's a tail call. Otherwise, we cannot tell for sure
// what it is and conservatively reject the function's CFG.
bool IsEpilogue = false;
for (const auto &Instr : *BB) {
if (BC.MIA->isLeave(Instr) || BC.MIA->isPop(Instr)) {
IsEpilogue = true;
break;
}
}
if (!IsEpilogue) {
if (opts::Verbosity >= 2) {
outs() << "BOLT-INFO: rejected potential indirect tail call in "
<< "function " << *this << " in basic block "
<< BB->getName() << ".\n";
DEBUG(BC.printInstructions(dbgs(), BB->begin(), BB->end(),
BB->getOffset(), this, true));
}
return false;
}
BC.MIA->convertJmpToTailCall(Instr, BC.Ctx.get());
}
}
return true;
}
void BinaryFunction::recomputeLandingPads() {
updateBBIndices(0);
for (auto *BB : BasicBlocks) {
BB->LandingPads.clear();
BB->Throwers.clear();
}
for (auto *BB : BasicBlocks) {
std::unordered_set<const BinaryBasicBlock *> BBLandingPads;
for (auto &Instr : *BB) {
if (!BC.MIA->isInvoke(Instr))
continue;
const MCSymbol *LPLabel;
uint64_t Action;
std::tie(LPLabel, Action) = BC.MIA->getEHInfo(Instr);
if (!LPLabel)
continue;
auto *LPBlock = getBasicBlockForLabel(LPLabel);
if (!BBLandingPads.count(LPBlock)) {
BBLandingPads.insert(LPBlock);
BB->LandingPads.emplace_back(LPBlock);
LPBlock->Throwers.emplace_back(BB);
}
}
}
}
bool BinaryFunction::buildCFG() {
NamedRegionTimer T("build cfg", TimerGroupName, opts::TimeBuild);
auto &MIA = BC.MIA;
if (!isSimple()) {
assert(!BC.HasRelocations &&
"cannot process file with non-simple function in relocs mode");
return false;
}
if (!(CurrentState == State::Disassembled))
return false;
assert(BasicBlocks.empty() && "basic block list should be empty");
assert((Labels.find(0) != Labels.end()) &&
"first instruction should always have a label");
// Create basic blocks in the original layout order:
//
// * Every instruction with associated label marks
// the beginning of a basic block.
// * Conditional instruction marks the end of a basic block,
// except when the following instruction is an
// unconditional branch, and the unconditional branch is not
// a destination of another branch. In the latter case, the
// basic block will consist of a single unconditional branch
// (missed "double-jump" optimization).
//
// Created basic blocks are sorted in layout order since they are
// created in the same order as instructions, and instructions are
// sorted by offsets.
BinaryBasicBlock *InsertBB{nullptr};
BinaryBasicBlock *PrevBB{nullptr};
bool IsLastInstrNop{false};
const MCInst *PrevInstr{nullptr};
auto addCFIPlaceholders =
[this](uint64_t CFIOffset, BinaryBasicBlock *InsertBB) {
for (auto FI = OffsetToCFI.lower_bound(CFIOffset),
FE = OffsetToCFI.upper_bound(CFIOffset);
FI != FE; ++FI) {
addCFIPseudo(InsertBB, InsertBB->end(), FI->second);
}
};
for (auto I = Instructions.begin(), E = Instructions.end(); I != E; ++I) {
const auto Offset = I->first;
const auto &Instr = I->second;
auto LI = Labels.find(Offset);
if (LI != Labels.end()) {
// Always create new BB at branch destination.
PrevBB = InsertBB;
InsertBB = addBasicBlock(LI->first, LI->second,
/* DeriveAlignment = */ IsLastInstrNop);
if (hasEntryPointAtOffset(Offset))
InsertBB->setEntryPoint();
}
// Ignore nops. We use nops to derive alignment of the next basic block.
// It will not always work, as some blocks are naturally aligned, but
// it's just part of heuristic for block alignment.
if (MIA->isNoop(Instr) && !PreserveNops) {
IsLastInstrNop = true;
continue;
}
if (!InsertBB) {
// It must be a fallthrough or unreachable code. Create a new block unless
// we see an unconditional branch following a conditional one. The latter
// should not be a conditional tail call.
assert(PrevBB && "no previous basic block for a fall through");
assert(PrevInstr && "no previous instruction for a fall through");
if (MIA->isUnconditionalBranch(Instr) &&
!MIA->isUnconditionalBranch(*PrevInstr) &&
!MIA->getConditionalTailCall(*PrevInstr)) {
// Temporarily restore inserter basic block.
InsertBB = PrevBB;
} else {
InsertBB = addBasicBlock(Offset,
BC.Ctx->createTempSymbol("FT", true),
/* DeriveAlignment = */ IsLastInstrNop);
}
}
if (Offset == 0) {
// Add associated CFI pseudos in the first offset (0)
addCFIPlaceholders(0, InsertBB);
}
IsLastInstrNop = false;
InsertBB->addInstruction(Instr);
PrevInstr = &Instr;
// Add associated CFI instrs. We always add the CFI instruction that is
// located immediately after this instruction, since the next CFI
// instruction reflects the change in state caused by this instruction.
auto NextInstr = std::next(I);
uint64_t CFIOffset;
if (NextInstr != E)
CFIOffset = NextInstr->first;
else
CFIOffset = getSize();
addCFIPlaceholders(CFIOffset, InsertBB);
if (MIA->isTerminator(Instr)) {
PrevBB = InsertBB;
InsertBB = nullptr;
}
}
if (BasicBlocks.empty()) {
setSimple(false);
return false;
}
// Intermediate dump.
DEBUG(print(dbgs(), "after creating basic blocks"));
// TODO: handle properly calls to no-return functions,
// e.g. exit(3), etc. Otherwise we'll see a false fall-through
// blocks.
for (auto &Branch : TakenBranches) {
DEBUG(dbgs() << "registering branch [0x" << Twine::utohexstr(Branch.first)
<< "] -> [0x" << Twine::utohexstr(Branch.second) << "]\n");
auto *FromBB = getBasicBlockContainingOffset(Branch.first);
assert(FromBB && "cannot find BB containing FROM branch");
auto *ToBB = getBasicBlockAtOffset(Branch.second);
assert(ToBB && "cannot find BB containing TO branch");
FromBB->addSuccessor(ToBB);
}
// Add fall-through branches.
PrevBB = nullptr;
bool IsPrevFT = false; // Is previous block a fall-through.
for (auto BB : BasicBlocks) {
if (IsPrevFT) {
PrevBB->addSuccessor(BB);
}
if (BB->empty()) {
IsPrevFT = true;
PrevBB = BB;
continue;
}
auto LastInstr = BB->getLastNonPseudoInstr();
assert(LastInstr &&
"should have non-pseudo instruction in non-empty block");
if (BB->succ_size() == 0) {
// Since there's no existing successors, we know the last instruction is
// not a conditional branch. Thus if it's a terminator, it shouldn't be a
// fall-through.
//
// Conditional tail call is a special case since we don't add a taken
// branch successor for it.
IsPrevFT = !MIA->isTerminator(*LastInstr) ||
MIA->getConditionalTailCall(*LastInstr);
} else if (BB->succ_size() == 1) {
IsPrevFT = MIA->isConditionalBranch(*LastInstr);
} else {
IsPrevFT = false;
}
PrevBB = BB;
}
if (!IsPrevFT) {
// Possibly a call that does not return.
DEBUG(dbgs() << "last block was marked as a fall-through in " << *this
<< '\n');
}
// Assign landing pads and throwers info.
recomputeLandingPads();
// Assign CFI information to each BB entry.
annotateCFIState();
// Annotate invoke instructions with GNU_args_size data.
propagateGnuArgsSizeInfo();
// Set the basic block layout to the original order and set end offsets.
PrevBB = nullptr;
for (auto BB : BasicBlocks) {
BasicBlocksLayout.emplace_back(BB);
if (PrevBB)
PrevBB->setEndOffset(BB->getOffset());
PrevBB = BB;
}
PrevBB->setEndOffset(getSize());
updateLayoutIndices();
// Update the state.
CurrentState = State::CFG;
return true;
}
void BinaryFunction::postProcessCFG() {
if (isSimple() && !BasicBlocks.empty()) {
// Convert conditional tail call branches to conditional branches that jump
// to a tail call.
removeConditionalTailCalls();
// Make any necessary adjustments for indirect branches.
if (!postProcessIndirectBranches()) {
if (opts::Verbosity) {
errs() << "BOLT-WARNING: failed to post-process indirect branches for "
<< *this << '\n';
}
// In relocation mode we want to keep processing the function but avoid
// optimizing it.
setSimple(false);
} else {
postProcessProfile();
// Eliminate inconsistencies between branch instructions and CFG.
postProcessBranches();
}
}
// Clean-up memory taken by instructions and labels.
//
// NB: don't clear Labels list as we may need them if we mark the function
// as non-simple later in the process of discovering extra entry points.
clearList(Instructions);
clearList(OffsetToCFI);
clearList(TakenBranches);
clearList(IgnoredBranches);
clearList(EntryOffsets);
// Remove "Offset" annotations from instructions that don't need those.
for (auto *BB : layout()) {
for (auto &Inst : *BB) {
if (BC.MIA->isCall(Inst) || BC.MIA->isIndirectBranch(Inst))
continue;
BC.MIA->removeAnnotation(Inst, "Offset");
}
}
assert((!isSimple() || validateCFG())
&& "Invalid CFG detected after post-processing CFG");
}
void BinaryFunction::removeTagsFromProfile() {
for (auto *BB : BasicBlocks) {
if (BB->ExecutionCount == BinaryBasicBlock::COUNT_NO_PROFILE)
BB->ExecutionCount = 0;
for (auto &BI : BB->branch_info()) {
if (BI.Count != BinaryBasicBlock::COUNT_NO_PROFILE &&
BI.MispredictedCount != BinaryBasicBlock::COUNT_NO_PROFILE)
continue;
BI.Count = 0;
BI.MispredictedCount = 0;
}
}
}
void BinaryFunction::addEntryPoint(uint64_t Address) {
assert(containsAddress(Address) && "address does not belong to the function");
auto Offset = Address - getAddress();
DEBUG(dbgs() << "BOLT-INFO: adding external entry point to function " << *this
<< " at offset 0x" << Twine::utohexstr(Address - getAddress())
<< '\n');
auto *EntrySymbol = BC.getGlobalSymbolAtAddress(Address);
// If we haven't disassembled the function yet we can add a new entry point
// even if it doesn't have an associated entry in the symbol table.
if (CurrentState == State::Empty) {
if (!EntrySymbol) {
DEBUG(dbgs() << "creating local label\n");
EntrySymbol = getOrCreateLocalLabel(Address);
} else {
DEBUG(dbgs() << "using global symbol " << EntrySymbol->getName() << '\n');
}
addEntryPointAtOffset(Address - getAddress());
Labels.emplace(Offset, EntrySymbol);
return;
}
assert(EntrySymbol && "expected symbol at address");
if (isSimple()) {
// Find basic block corresponding to the address and substitute label.
auto *BB = getBasicBlockAtOffset(Offset);
if (!BB) {
// TODO #14762450: split basic block and process function.
if (opts::Verbosity || BC.HasRelocations) {
errs() << "BOLT-WARNING: no basic block at offset 0x"
<< Twine::utohexstr(Offset) << " in function " << *this
<< ". Marking non-simple.\n";
}
setSimple(false);
} else {
BB->setLabel(EntrySymbol);
BB->setEntryPoint(true);
}
}
// Fix/append labels list.
auto LI = Labels.find(Offset);
if (LI != Labels.end()) {
LI->second = EntrySymbol;
} else {
Labels.emplace(Offset, EntrySymbol);
}
}
void BinaryFunction::removeConditionalTailCalls() {
// Blocks to be appended at the end.
std::vector<std::unique_ptr<BinaryBasicBlock>> NewBlocks;
for (auto BBI = begin(); BBI != end(); ++BBI) {
auto &BB = *BBI;
auto *CTCInstr = BB.getLastNonPseudoInstr();
if (!CTCInstr)
continue;
auto TargetAddressOrNone = BC.MIA->getConditionalTailCall(*CTCInstr);
if (!TargetAddressOrNone)
continue;
// Gather all necessary information about CTC instruction before
// annotations are destroyed.
const auto CFIStateBeforeCTC = BB.getCFIStateAtInstr(CTCInstr);
uint64_t CTCTakenCount = BinaryBasicBlock::COUNT_NO_PROFILE;
uint64_t CTCMispredCount = BinaryBasicBlock::COUNT_NO_PROFILE;
if (hasValidProfile()) {
CTCTakenCount =
BC.MIA->getAnnotationWithDefault<uint64_t>(*CTCInstr, "CTCTakenCount");
CTCMispredCount =
BC.MIA->getAnnotationWithDefault<uint64_t>(*CTCInstr,
"CTCMispredCount");
}
// Assert that the tail call does not throw.
const MCSymbol *LP;
uint64_t Action;
std::tie(LP, Action) = BC.MIA->getEHInfo(*CTCInstr);
assert(!LP && "found tail call with associated landing pad");
// Create a basic block with an unconditional tail call instruction using
// the same destination.
const auto *CTCTargetLabel = BC.MIA->getTargetSymbol(*CTCInstr);
assert(CTCTargetLabel && "symbol expected for conditional tail call");
MCInst TailCallInstr;
BC.MIA->createTailCall(TailCallInstr, CTCTargetLabel, BC.Ctx.get());
auto TailCallBB = createBasicBlock(BinaryBasicBlock::INVALID_OFFSET,
BC.Ctx->createTempSymbol("TC", true));
TailCallBB->addInstruction(TailCallInstr);
TailCallBB->setCFIState(CFIStateBeforeCTC);
// Add CFG edge with profile info from BB to TailCallBB.
BB.addSuccessor(TailCallBB.get(), CTCTakenCount, CTCMispredCount);
// Add execution count for the block.
TailCallBB->setExecutionCount(CTCTakenCount);
// In attempt to preserve the direction of the original conditional jump,
// we will either create an unconditional jump in a separate basic block
// at the end of the function, or reverse a condition of the jump
// and create a fall-through block right after the original tail call.
if (getAddress() >= *TargetAddressOrNone) {
// Insert the basic block right after the current one.
std::vector<std::unique_ptr<BinaryBasicBlock>> TCBB;
TCBB.emplace_back(std::move(TailCallBB));
BBI = insertBasicBlocks(BBI,
std::move(TCBB),
/* UpdateLayout */ true,
/* UpdateCFIState */ false);
BC.MIA->reverseBranchCondition(
*CTCInstr, (*std::next(BBI)).getLabel(), BC.Ctx.get());
} else {
BC.MIA->replaceBranchTarget(*CTCInstr, TailCallBB->getLabel(),
BC.Ctx.get());
// Add basic block to the list that will be added to the end.
NewBlocks.emplace_back(std::move(TailCallBB));
// Swap edges as the TailCallBB corresponds to the taken branch.
BB.swapConditionalSuccessors();
}
// This branch is no longer a conditional tail call.
BC.MIA->unsetConditionalTailCall(*CTCInstr);
}
insertBasicBlocks(std::prev(end()),
std::move(NewBlocks),
/* UpdateLayout */ true,
/* UpdateCFIState */ false);
}
uint64_t BinaryFunction::getFunctionScore() {
if (FunctionScore != -1)
return FunctionScore;
uint64_t TotalScore = 0ULL;
for (auto BB : layout()) {
uint64_t BBExecCount = BB->getExecutionCount();
if (BBExecCount == BinaryBasicBlock::COUNT_NO_PROFILE)
continue;
BBExecCount *= BB->getNumNonPseudos();
TotalScore += BBExecCount;
}
FunctionScore = TotalScore;
return FunctionScore;
}
void BinaryFunction::annotateCFIState() {
assert(CurrentState == State::Disassembled && "unexpected function state");
assert(!BasicBlocks.empty() && "basic block list should not be empty");
// This is an index of the last processed CFI in FDE CFI program.
uint32_t State = 0;
// This is an index of RememberState CFI reflecting effective state right
// after execution of RestoreState CFI.
//
// It differs from State iff the CFI at (State-1)
// was RestoreState (modulo GNU_args_size CFIs, which are ignored).
//
// This allows us to generate shorter replay sequences when producing new
// CFI programs.
uint32_t EffectiveState = 0;
// For tracking RememberState/RestoreState sequences.
std::stack<uint32_t> StateStack;
for (auto *BB : BasicBlocks) {
BB->setCFIState(EffectiveState);
for (const auto &Instr : *BB) {
const auto *CFI = getCFIFor(Instr);
if (!CFI)
continue;
++State;
switch (CFI->getOperation()) {
case MCCFIInstruction::OpRememberState:
StateStack.push(EffectiveState);
EffectiveState = State;
break;
case MCCFIInstruction::OpRestoreState:
assert(!StateStack.empty() && "corrupt CFI stack");
EffectiveState = StateStack.top();
StateStack.pop();
break;
case MCCFIInstruction::OpGnuArgsSize:
// OpGnuArgsSize CFIs do not affect the CFI state.
break;
default:
// Any other CFI updates the state.
EffectiveState = State;
break;
}
}
}
assert(StateStack.empty() && "corrupt CFI stack");
}
bool BinaryFunction::fixCFIState() {
DEBUG(dbgs() << "Trying to fix CFI states for each BB after reordering.\n");
DEBUG(dbgs() << "This is the list of CFI states for each BB of " << *this
<< ": ");
auto replayCFIInstrs =
[this](int32_t FromState, int32_t ToState, BinaryBasicBlock *InBB,
BinaryBasicBlock::iterator InsertIt) -> bool {
if (FromState == ToState)
return true;
assert(FromState < ToState && "can only replay CFIs forward");
std::vector<uint32_t> NewCFIs;
uint32_t NestedLevel = 0;
for (auto CurState = FromState; CurState < ToState; ++CurState) {
MCCFIInstruction *Instr = &FrameInstructions[CurState];
if (Instr->getOperation() == MCCFIInstruction::OpRememberState)
++NestedLevel;
if (!NestedLevel)
NewCFIs.push_back(CurState);
if (Instr->getOperation() == MCCFIInstruction::OpRestoreState)
--NestedLevel;
}
// TODO: If in replaying the CFI instructions to reach this state we
// have state stack instructions, we could still work out the logic
// to extract only the necessary instructions to reach this state
// without using the state stack. Not sure if it is worth the effort
// because this happens rarely.
if (NestedLevel != 0) {
errs() << "BOLT-WARNING: CFI rewriter detected nested CFI state"
<< " while replaying CFI instructions for BB "
<< InBB->getName() << " in function " << *this << '\n';
return false;
}
for (auto CFI : NewCFIs) {
// Ignore GNU_args_size instructions.
if (FrameInstructions[CFI].getOperation() !=
MCCFIInstruction::OpGnuArgsSize) {
InsertIt = addCFIPseudo(InBB, InsertIt, CFI);
++InsertIt;
}
}
return true;
};
int32_t State = 0;
auto *FDEStartBB = BasicBlocksLayout[0];
bool SeenCold = false;
auto Sep = "";
(void)Sep;
for (auto *BB : BasicBlocksLayout) {
const auto CFIStateAtExit = BB->getCFIStateAtExit();
// Hot-cold border: check if this is the first BB to be allocated in a cold
// region (with a different FDE). If yes, we need to reset the CFI state and
// the FDEStartBB that is used to insert remember_state CFIs.
if (!SeenCold && BB->isCold()) {
State = 0;
FDEStartBB = BB;
SeenCold = true;
}
// We need to recover the correct state if it doesn't match expected
// state at BB entry point.
if (BB->getCFIState() < State) {
// In this case, State is currently higher than what this BB expect it
// to be. To solve this, we need to insert a CFI instruction to remember
// the old state at function entry, then another CFI instruction to
// restore it at the entry of this BB and replay CFI instructions to
// reach the desired state.
int32_t OldState = BB->getCFIState();
// Remember state at function entry point (our reference state).
auto InsertIt = FDEStartBB->begin();
while (InsertIt != FDEStartBB->end() && BC.MIA->isCFI(*InsertIt))
++InsertIt;
addCFIPseudo(FDEStartBB, InsertIt, FrameInstructions.size());
FrameInstructions.emplace_back(
MCCFIInstruction::createRememberState(nullptr));
// Restore state
InsertIt = addCFIPseudo(BB, BB->begin(), FrameInstructions.size());
++InsertIt;
FrameInstructions.emplace_back(
MCCFIInstruction::createRestoreState(nullptr));
if (!replayCFIInstrs(0, OldState, BB, InsertIt))
return false;
// Check if we messed up the stack in this process
int StackOffset = 0;
for (BinaryBasicBlock *CurBB : BasicBlocksLayout) {
if (CurBB == BB)
break;
for (auto &Instr : *CurBB) {
if (auto *CFI = getCFIFor(Instr)) {
if (CFI->getOperation() == MCCFIInstruction::OpRememberState)
++StackOffset;
if (CFI->getOperation() == MCCFIInstruction::OpRestoreState)
--StackOffset;
}
}
}
auto Pos = BB->begin();
while (Pos != BB->end() && BC.MIA->isCFI(*Pos)) {
auto CFI = getCFIFor(*Pos);
if (CFI->getOperation() == MCCFIInstruction::OpRememberState)
++StackOffset;
if (CFI->getOperation() == MCCFIInstruction::OpRestoreState)
--StackOffset;
++Pos;
}
if (StackOffset != 0) {
errs() << "BOLT-WARNING: not possible to remember/recover state"
<< " without corrupting CFI state stack in function "
<< *this << " @ " << BB->getName() << "\n";
return false;
}
} else if (BB->getCFIState() > State) {
// If BB's CFI state is greater than State, it means we are behind in the
// state. Just emit all instructions to reach this state at the
// beginning of this BB. If this sequence of instructions involve
// remember state or restore state, bail out.
if (!replayCFIInstrs(State, BB->getCFIState(), BB, BB->begin()))
return false;
}
State = CFIStateAtExit;
DEBUG(dbgs() << Sep << State; Sep = ", ");
}
DEBUG(dbgs() << "\n");
return true;
}
uint64_t BinaryFunction::getInstructionCount() const {
uint64_t Count = 0;
for (auto &Block : BasicBlocksLayout) {
Count += Block->getNumNonPseudos();
}
return Count;
}
bool BinaryFunction::hasLayoutChanged() const {
return BasicBlocksPreviousLayout != BasicBlocksLayout;
}
uint64_t BinaryFunction::getEditDistance() const {
return ComputeEditDistance<BinaryBasicBlock *>(BasicBlocksPreviousLayout,
BasicBlocksLayout);
}
void BinaryFunction::emitBody(MCStreamer &Streamer, bool EmitColdPart) {
int64_t CurrentGnuArgsSize = 0;
for (auto BB : layout()) {
if (EmitColdPart != BB->isCold())
continue;
if (opts::AlignBlocks && BB->getAlignment() > 1)
Streamer.EmitCodeAlignment(BB->getAlignment());
Streamer.EmitLabel(BB->getLabel());
// Remember if last instruction emitted was a prefix
bool LastIsPrefix = false;
SMLoc LastLocSeen;
for (auto I = BB->begin(), E = BB->end(); I != E; ++I) {
auto &Instr = *I;
// Handle pseudo instructions.
if (BC.MIA->isEHLabel(Instr)) {
const auto *Label = BC.MIA->getTargetSymbol(Instr);
assert(Instr.getNumOperands() == 1 && Label &&
"bad EH_LABEL instruction");
Streamer.EmitLabel(const_cast<MCSymbol *>(Label));
continue;
}
if (BC.MIA->isCFI(Instr)) {
Streamer.EmitCFIInstruction(*getCFIFor(Instr));
continue;
}
if (opts::UpdateDebugSections && UnitLineTable.first) {
LastLocSeen = emitLineInfo(Instr.getLoc(), LastLocSeen);
}
// Emit GNU_args_size CFIs as necessary.
if (usesGnuArgsSize() && BC.MIA->isInvoke(Instr)) {
auto NewGnuArgsSize = BC.MIA->getGnuArgsSize(Instr);
assert(NewGnuArgsSize >= 0 && "expected non-negative GNU_args_size");
if (NewGnuArgsSize != CurrentGnuArgsSize) {
CurrentGnuArgsSize = NewGnuArgsSize;
Streamer.EmitCFIGnuArgsSize(CurrentGnuArgsSize);
}
}
Streamer.EmitInstruction(Instr, *BC.STI);
LastIsPrefix = BC.MIA->isPrefix(Instr);
}
}
if (!EmitColdPart)
emitConstantIslands(Streamer);
}
void BinaryFunction::emitBodyRaw(MCStreamer *Streamer) {
// #14998851: Fix gold linker's '--emit-relocs'.
assert(false &&
"cannot emit raw body unless relocation accuracy is guaranteed");
// Raw contents of the function.
StringRef SectionContents;
Section.getContents(SectionContents);
// Raw contents of the function.
StringRef FunctionContents =
SectionContents.substr(getAddress() - Section.getAddress(),
getSize());
if (opts::Verbosity)
outs() << "BOLT-INFO: emitting function " << *this << " in raw ("
<< getSize() << " bytes).\n";
// We split the function blob into smaller blocks and output relocations
// and/or labels between them.
uint64_t FunctionOffset = 0;
auto LI = Labels.begin();
auto RI = MoveRelocations.begin();
while (LI != Labels.end() ||
RI != MoveRelocations.end()) {
uint64_t NextLabelOffset = (LI == Labels.end() ? getSize() : LI->first);
uint64_t NextRelocationOffset =
(RI == MoveRelocations.end() ? getSize() : RI->first);
auto NextStop = std::min(NextLabelOffset, NextRelocationOffset);
assert(NextStop <= getSize() && "internal overflow error");
if (FunctionOffset < NextStop) {
Streamer->EmitBytes(
FunctionContents.slice(FunctionOffset, NextStop));
FunctionOffset = NextStop;
}
if (LI != Labels.end() && FunctionOffset == LI->first) {
Streamer->EmitLabel(LI->second);
DEBUG(dbgs() << "BOLT-DEBUG: emitted label " << LI->second->getName()
<< " at offset 0x" << Twine::utohexstr(LI->first) << '\n');
++LI;
}
if (RI != MoveRelocations.end() && FunctionOffset == RI->first) {
auto RelocationSize = RI->second.emit(Streamer);
DEBUG(dbgs() << "BOLT-DEBUG: emitted relocation for symbol "
<< RI->second.Symbol->getName() << " at offset 0x"
<< Twine::utohexstr(RI->first)
<< " with size " << RelocationSize << '\n');
FunctionOffset += RelocationSize;
++RI;
}
}
assert(FunctionOffset <= getSize() && "overflow error");
if (FunctionOffset < getSize()) {
Streamer->EmitBytes(FunctionContents.substr(FunctionOffset));
}
}
void BinaryFunction::emitConstantIslands(MCStreamer &Streamer) {
if (DataOffsets.empty())
return;
Streamer.EmitLabel(getFunctionConstantIslandLabel());
// Raw contents of the function.
StringRef SectionContents;
Section.getContents(SectionContents);
// Raw contents of the function.
StringRef FunctionContents =
SectionContents.substr(getAddress() - Section.getAddress(),
getMaxSize());
if (opts::Verbosity)
outs() << "BOLT-INFO: emitting constant island for function " << *this
<< "\n";
// We split the island into smaller blocks and output labels between them.
auto IS = IslandSymbols.begin();
for (auto DataIter = DataOffsets.begin(); DataIter != DataOffsets.end();
++DataIter) {
uint64_t FunctionOffset = *DataIter;
uint64_t EndOffset = 0ULL;
// Determine size of this data chunk
auto NextData = std::next(DataIter);
auto CodeIter = CodeOffsets.lower_bound(*DataIter);
if (CodeIter == CodeOffsets.end() && NextData == DataOffsets.end()) {
EndOffset = getMaxSize();
} else if (CodeIter == CodeOffsets.end()) {
EndOffset = *NextData;
} else if (NextData == DataOffsets.end()) {
EndOffset = *CodeIter;
} else {
EndOffset = (*CodeIter > *NextData) ? *NextData : *CodeIter;
}
if (FunctionOffset == EndOffset)
continue; // Size is zero, nothing to emit
// Emit labels, relocs and data
auto RI = MoveRelocations.lower_bound(FunctionOffset);
while ((IS != IslandSymbols.end() && IS->first < EndOffset) ||
(RI != MoveRelocations.end() && RI->first < EndOffset)) {
auto NextLabelOffset = IS == IslandSymbols.end() ? EndOffset : IS->first;
auto NextRelOffset = RI == MoveRelocations.end() ? EndOffset : RI->first;
auto NextStop = std::min(NextLabelOffset, NextRelOffset);
assert(NextStop <= EndOffset && "internal overflow error");
if (FunctionOffset < NextStop) {
Streamer.EmitBytes(FunctionContents.slice(FunctionOffset, NextStop));
FunctionOffset = NextStop;
}
if (IS != IslandSymbols.end() && FunctionOffset == IS->first) {
DEBUG(dbgs() << "BOLT-DEBUG: emitted label " << IS->second->getName()
<< " at offset 0x" << Twine::utohexstr(IS->first) << '\n');
Streamer.EmitLabel(IS->second);
++IS;
}
if (RI != MoveRelocations.end() && FunctionOffset == RI->first) {
auto RelocationSize = RI->second.emit(&Streamer);
DEBUG(dbgs() << "BOLT-DEBUG: emitted relocation for symbol "
<< RI->second.Symbol->getName() << " at offset 0x"
<< Twine::utohexstr(RI->first)
<< " with size " << RelocationSize << '\n');
FunctionOffset += RelocationSize;
++RI;
}
}
assert(FunctionOffset <= EndOffset && "overflow error");
if (FunctionOffset < EndOffset) {
Streamer.EmitBytes(FunctionContents.slice(FunctionOffset, EndOffset));
}
}
assert(IS == IslandSymbols.end() && "some symbols were not emitted!");
}
namespace {
#ifndef MAX_PATH
#define MAX_PATH 255
#endif
std::string constructFilename(std::string Filename,
std::string Annotation,
std::string Suffix) {
std::replace(Filename.begin(), Filename.end(), '/', '-');
if (!Annotation.empty()) {
Annotation.insert(0, "-");
}
if (Filename.size() + Annotation.size() + Suffix.size() > MAX_PATH) {
assert(Suffix.size() + Annotation.size() <= MAX_PATH);
if (opts::Verbosity >= 1) {
errs() << "BOLT-WARNING: Filename \"" << Filename << Annotation << Suffix
<< "\" exceeds the " << MAX_PATH << " size limit, truncating.\n";
}
Filename.resize(MAX_PATH - (Suffix.size() + Annotation.size()));
}
Filename += Annotation;
Filename += Suffix;
return Filename;
}
std::string formatEscapes(const std::string& Str) {
std::string Result;
for (unsigned I = 0; I < Str.size(); ++I) {
auto C = Str[I];
switch (C) {
case '\n':
Result += "&#13;";
break;
case '"':
break;
default:
Result += C;
break;
}
}
return Result;
}
}
void BinaryFunction::dumpGraph(raw_ostream& OS) const {
OS << "strict digraph \"" << getPrintName() << "\" {\n";
uint64_t Offset = Address;
for (auto *BB : BasicBlocks) {
auto LayoutPos = std::find(BasicBlocksLayout.begin(),
BasicBlocksLayout.end(),
BB);
unsigned Layout = LayoutPos - BasicBlocksLayout.begin();
const char* ColdStr = BB->isCold() ? " (cold)" : "";
OS << format("\"%s\" [label=\"%s%s\\n(C:%lu,O:%lu,I:%u,L:%u:CFI:%u)\"]\n",
BB->getName().data(),
BB->getName().data(),
ColdStr,
(BB->ExecutionCount != BinaryBasicBlock::COUNT_NO_PROFILE
? BB->ExecutionCount
: 0),
BB->getOffset(),
getIndex(BB),
Layout,
BB->getCFIState());
OS << format("\"%s\" [shape=box]\n", BB->getName().data());
if (opts::DotToolTipCode) {
std::string Str;
raw_string_ostream CS(Str);
Offset = BC.printInstructions(CS, BB->begin(), BB->end(), Offset, this);
const auto Code = formatEscapes(CS.str());
OS << format("\"%s\" [tooltip=\"%s\"]\n",
BB->getName().data(),
Code.c_str());
}
// analyzeBranch is just used to get the names of the branch
// opcodes.
const MCSymbol *TBB = nullptr;
const MCSymbol *FBB = nullptr;
MCInst *CondBranch = nullptr;
MCInst *UncondBranch = nullptr;
const bool Success = BB->analyzeBranch(TBB,
FBB,
CondBranch,
UncondBranch);
const auto *LastInstr = BB->getLastNonPseudoInstr();
const bool IsJumpTable = LastInstr && BC.MIA->getJumpTable(*LastInstr);
auto BI = BB->branch_info_begin();
for (auto *Succ : BB->successors()) {
std::string Branch;
if (Success) {
if (Succ == BB->getConditionalSuccessor(true)) {
Branch = CondBranch
? BC.InstPrinter->getOpcodeName(CondBranch->getOpcode())
: "TB";
} else if (Succ == BB->getConditionalSuccessor(false)) {
Branch = UncondBranch
? BC.InstPrinter->getOpcodeName(UncondBranch->getOpcode())
: "FB";
} else {
Branch = "FT";
}
}
if (IsJumpTable) {
Branch = "JT";
}
OS << format("\"%s\" -> \"%s\" [label=\"%s",
BB->getName().data(),
Succ->getName().data(),
Branch.c_str());
if (BB->getExecutionCount() != COUNT_NO_PROFILE &&
BI->MispredictedCount != BinaryBasicBlock::COUNT_INFERRED) {
OS << "\\n(C:" << BI->Count << ",M:" << BI->MispredictedCount << ")";
} else if (ExecutionCount != COUNT_NO_PROFILE &&
BI->Count != BinaryBasicBlock::COUNT_NO_PROFILE) {
OS << "\\n(IC:" << BI->Count << ")";
}
OS << "\"]\n";
++BI;
}
for (auto *LP : BB->landing_pads()) {
OS << format("\"%s\" -> \"%s\" [constraint=false style=dashed]\n",
BB->getName().data(),
LP->getName().data());
}
}
OS << "}\n";
}
void BinaryFunction::viewGraph() const {
SmallString<MAX_PATH> Filename;
if (auto EC = sys::fs::createTemporaryFile("bolt-cfg", "dot", Filename)) {
errs() << "BOLT-ERROR: " << EC.message() << ", unable to create "
<< " bolt-cfg-XXXXX.dot temporary file.\n";
return;
}
dumpGraphToFile(Filename.str());
if (DisplayGraph(Filename)) {
errs() << "BOLT-ERROR: Can't display " << Filename << " with graphviz.\n";
}
if (auto EC = sys::fs::remove(Filename)) {
errs() << "BOLT-WARNING: " << EC.message() << ", failed to remove "
<< Filename << "\n";
}
}
void BinaryFunction::dumpGraphForPass(std::string Annotation) const {
auto Filename = constructFilename(getPrintName(), Annotation, ".dot");
outs() << "BOLT-DEBUG: Dumping CFG to " << Filename << "\n";
dumpGraphToFile(Filename);
}
void BinaryFunction::dumpGraphToFile(std::string Filename) const {
std::error_code EC;
raw_fd_ostream of(Filename, EC, sys::fs::F_None);
if (EC) {
if (opts::Verbosity >= 1) {
errs() << "BOLT-WARNING: " << EC.message() << ", unable to open "
<< Filename << " for output.\n";
}
return;
}
dumpGraph(of);
}
bool BinaryFunction::validateCFG() const {
bool Valid = true;
for (auto *BB : BasicBlocks) {
Valid &= BB->validateSuccessorInvariants();
}
if (!Valid)
return Valid;
for (const auto *BB : BasicBlocks) {
std::unordered_set<const BinaryBasicBlock *> BBLandingPads;
for (const auto *LP : BB->landing_pads()) {
if (BBLandingPads.count(LP)) {
errs() << "BOLT-ERROR: duplicate landing pad detected in"
<< BB->getName() << " in function " << *this << '\n';
return false;
}
BBLandingPads.insert(LP);
}
std::unordered_set<const BinaryBasicBlock *> BBThrowers;
for (const auto *Thrower : BB->throwers()) {
if (BBThrowers.count(Thrower)) {
errs() << "BOLT-ERROR: duplicate thrower detected in"
<< BB->getName() << " in function " << *this << '\n';
return false;
}
BBThrowers.insert(Thrower);
}
for (const auto *LPBlock : BB->landing_pads()) {
if (std::find(LPBlock->throw_begin(), LPBlock->throw_end(), BB)
== LPBlock->throw_end()) {
errs() << "BOLT-ERROR: inconsistent landing pad detected in "
<< *this << ": " << BB->getName()
<< " is in LandingPads but not in " << LPBlock->getName()
<< " Throwers\n";
return false;
}
}
for (const auto *Thrower : BB->throwers()) {
if (std::find(Thrower->lp_begin(), Thrower->lp_end(), BB)
== Thrower->lp_end()) {
errs() << "BOLT-ERROR: inconsistent thrower detected in "
<< *this << ": " << BB->getName()
<< " is in Throwers list but not in " << Thrower->getName()
<< " LandingPads\n";
return false;
}
}
}
return Valid;
}
void BinaryFunction::fixBranches() {
auto &MIA = BC.MIA;
auto *Ctx = BC.Ctx.get();
for (unsigned I = 0, E = BasicBlocksLayout.size(); I != E; ++I) {
BinaryBasicBlock *BB = BasicBlocksLayout[I];
const MCSymbol *TBB = nullptr;
const MCSymbol *FBB = nullptr;
MCInst *CondBranch = nullptr;
MCInst *UncondBranch = nullptr;
if (!BB->analyzeBranch(TBB, FBB, CondBranch, UncondBranch))
continue;
// We will create unconditional branch with correct destination if needed.
if (UncondBranch)
BB->eraseInstruction(UncondBranch);
// Basic block that follows the current one in the final layout.
const BinaryBasicBlock *NextBB = nullptr;
if (I + 1 != E && BB->isCold() == BasicBlocksLayout[I + 1]->isCold())
NextBB = BasicBlocksLayout[I + 1];
if (BB->succ_size() == 1) {
// __builtin_unreachable() could create a conditional branch that
// falls-through into the next function - hence the block will have only
// one valid successor. Since behaviour is undefined - we replace
// the conditional branch with an unconditional if required.
if (CondBranch)
BB->eraseInstruction(CondBranch);
if (BB->getSuccessor() == NextBB)
continue;
BB->addBranchInstruction(BB->getSuccessor());
} else if (BB->succ_size() == 2) {
assert(CondBranch && "conditional branch expected");
const auto *TSuccessor = BB->getConditionalSuccessor(true);
const auto *FSuccessor = BB->getConditionalSuccessor(false);
if (NextBB && NextBB == TSuccessor) {
std::swap(TSuccessor, FSuccessor);
MIA->reverseBranchCondition(*CondBranch, TSuccessor->getLabel(), Ctx);
BB->swapConditionalSuccessors();
} else {
MIA->replaceBranchTarget(*CondBranch, TSuccessor->getLabel(), Ctx);
}
if (TSuccessor == FSuccessor) {
BB->removeDuplicateConditionalSuccessor(CondBranch);
}
if (!NextBB || (NextBB != TSuccessor && NextBB != FSuccessor)) {
BB->addBranchInstruction(FSuccessor);
}
}
// Cases where the number of successors is 0 (block ends with a
// terminator) or more than 2 (switch table) don't require branch
// instruction adjustments.
}
assert((!isSimple() || validateCFG())
&& "Invalid CFG detected after fixing branches");
}
void BinaryFunction::propagateGnuArgsSizeInfo() {
assert(CurrentState == State::Disassembled && "unexpected function state");
if (!hasEHRanges() || !usesGnuArgsSize())
return;
// The current value of DW_CFA_GNU_args_size affects all following
// invoke instructions until the next CFI overrides it.
// It is important to iterate basic blocks in the original order when
// assigning the value.
uint64_t CurrentGnuArgsSize = 0;
for (auto BB : BasicBlocks) {
for (auto II = BB->begin(); II != BB->end(); ) {
auto &Instr = *II;
if (BC.MIA->isCFI(Instr)) {
auto CFI = getCFIFor(Instr);
if (CFI->getOperation() == MCCFIInstruction::OpGnuArgsSize) {
CurrentGnuArgsSize = CFI->getOffset();
// Delete DW_CFA_GNU_args_size instructions and only regenerate
// during the final code emission. The information is embedded
// inside call instructions.
II = BB->erasePseudoInstruction(II);
continue;
}
} else if (BC.MIA->isInvoke(Instr)) {
// Add the value of GNU_args_size as an extra operand to invokes.
BC.MIA->addGnuArgsSize(Instr, CurrentGnuArgsSize);
}
++II;
}
}
}
void BinaryFunction::postProcessBranches() {
if (!isSimple())
return;
for (auto *BB : BasicBlocksLayout) {
auto LastInstrRI = BB->getLastNonPseudo();
if (BB->succ_size() == 1) {
if (LastInstrRI != BB->rend() &&
BC.MIA->isConditionalBranch(*LastInstrRI)) {
// __builtin_unreachable() could create a conditional branch that
// falls-through into the next function - hence the block will have only
// one valid successor. Such behaviour is undefined and thus we remove
// the conditional branch while leaving a valid successor.
BB->eraseInstruction(std::next(LastInstrRI.base()));
DEBUG(dbgs() << "BOLT-DEBUG: erasing conditional branch in "
<< BB->getName() << " in function " << *this << '\n');
}
} else if (BB->succ_size() == 0) {
// Ignore unreachable basic blocks.
if (BB->pred_size() == 0 || BB->isLandingPad())
continue;
// If it's the basic block that does not end up with a terminator - we
// insert a return instruction unless it's a call instruction.
if (LastInstrRI == BB->rend()) {
DEBUG(dbgs() << "BOLT-DEBUG: at least one instruction expected in BB "
<< BB->getName() << " in function " << *this << '\n');
continue;
}
if (!BC.MIA->isTerminator(*LastInstrRI) &&
!BC.MIA->isCall(*LastInstrRI)) {
DEBUG(dbgs() << "BOLT-DEBUG: adding return to basic block "
<< BB->getName() << " in function " << *this << '\n');
MCInst ReturnInstr;
BC.MIA->createReturn(ReturnInstr);
BB->addInstruction(ReturnInstr);
}
}
}
assert(validateCFG() && "invalid CFG");
}
BinaryFunction::BasicBlockOrderType BinaryFunction::dfs() const {
BasicBlockOrderType DFS;
unsigned Index = 0;
std::stack<BinaryBasicBlock *> Stack;
// Push entry points to the stack in reverse order.
//
// NB: we rely on the original order of entries to match.
for (auto BBI = layout_rbegin(); BBI != layout_rend(); ++BBI) {
auto *BB = *BBI;
if (BB->isEntryPoint())
Stack.push(BB);
BB->setLayoutIndex(BinaryBasicBlock::InvalidIndex);
}
while (!Stack.empty()) {
auto *BB = Stack.top();
Stack.pop();
if (BB->getLayoutIndex() != BinaryBasicBlock::InvalidIndex)
continue;
BB->setLayoutIndex(Index++);
DFS.push_back(BB);
for (auto *SuccBB : BB->landing_pads()) {
Stack.push(SuccBB);
}
for (auto *SuccBB : BB->successors()) {
Stack.push(SuccBB);
}
}
return DFS;
}
bool BinaryFunction::isIdenticalWith(const BinaryFunction &OtherBF,
bool IgnoreSymbols,
bool UseDFS) const {
assert(hasCFG() && OtherBF.hasCFG() && "both functions should have CFG");
// Compare the two functions, one basic block at a time.
// Currently we require two identical basic blocks to have identical
// instruction sequences and the same index in their corresponding
// functions. The latter is important for CFG equality.
if (layout_size() != OtherBF.layout_size())
return false;
// Comparing multi-entry functions could be non-trivial.
if (isMultiEntry() || OtherBF.isMultiEntry())
return false;
// Process both functions in either DFS or existing order.
const auto &Order = UseDFS ? dfs() : BasicBlocksLayout;
const auto &OtherOrder = UseDFS ? OtherBF.dfs() : OtherBF.BasicBlocksLayout;
auto BBI = OtherOrder.begin();
for (const auto *BB : Order) {
const auto *OtherBB = *BBI;
if (BB->getLayoutIndex() != OtherBB->getLayoutIndex())
return false;
// Compare successor basic blocks.
// NOTE: the comparison for jump tables is only partially verified here.
if (BB->succ_size() != OtherBB->succ_size())
return false;
auto SuccBBI = OtherBB->succ_begin();
for (const auto *SuccBB : BB->successors()) {
const auto *SuccOtherBB = *SuccBBI;
if (SuccBB->getLayoutIndex() != SuccOtherBB->getLayoutIndex())
return false;
++SuccBBI;
}
// Compare all instructions including pseudos.
auto I = BB->begin(), E = BB->end();
auto OtherI = OtherBB->begin(), OtherE = OtherBB->end();
while (I != E && OtherI != OtherE) {
bool Identical;
if (IgnoreSymbols) {
Identical =
isInstrEquivalentWith(*I, *BB, *OtherI, *OtherBB, OtherBF,
[](const MCSymbol *A, const MCSymbol *B) {
return true;
});
} else {
// Compare symbols.
auto AreSymbolsIdentical = [&] (const MCSymbol *A, const MCSymbol *B) {
if (A == B)
return true;
// All local symbols are considered identical since they affect a
// control flow and we check the control flow separately.
// If a local symbol is escaped, then the function (potentially) has
// multiple entry points and we exclude such functions from
// comparison.
if (A->isTemporary() && B->isTemporary())
return true;
// Compare symbols as functions.
const auto *FunctionA = BC.getFunctionForSymbol(A);
const auto *FunctionB = BC.getFunctionForSymbol(B);
if (FunctionA && FunctionB) {
// Self-referencing functions and recursive calls.
if (FunctionA == this && FunctionB == &OtherBF)
return true;
return FunctionA == FunctionB;
}
// Check if symbols are jump tables.
auto SIA = BC.GlobalSymbols.find(A->getName());
if (SIA == BC.GlobalSymbols.end())
return false;
auto SIB = BC.GlobalSymbols.find(B->getName());
if (SIB == BC.GlobalSymbols.end())
return false;
assert((SIA->second != SIB->second) &&
"different symbols should not have the same value");
const auto *JumpTableA = getJumpTableContainingAddress(SIA->second);
if (!JumpTableA)
return false;
const auto *JumpTableB =
OtherBF.getJumpTableContainingAddress(SIB->second);
if (!JumpTableB)
return false;
if ((SIA->second - JumpTableA->Address) !=
(SIB->second - JumpTableB->Address))
return false;
return equalJumpTables(JumpTableA, JumpTableB, OtherBF);
};
Identical =
isInstrEquivalentWith(*I, *BB, *OtherI, *OtherBB, OtherBF,
AreSymbolsIdentical);
}
if (!Identical)
return false;
++I; ++OtherI;
}
// One of the identical blocks may have a trailing unconditional jump that
// is ignored for CFG purposes.
auto *TrailingInstr = (I != E ? &(*I)
: (OtherI != OtherE ? &(*OtherI) : 0));
if (TrailingInstr && !BC.MIA->isUnconditionalBranch(*TrailingInstr)) {
return false;
}
++BBI;
}
return true;
}
bool BinaryFunction::equalJumpTables(const JumpTable *JumpTableA,
const JumpTable *JumpTableB,
const BinaryFunction &BFB) const {
if (JumpTableA->EntrySize != JumpTableB->EntrySize)
return false;
if (JumpTableA->Type != JumpTableB->Type)
return false;
if (JumpTableA->getSize() != JumpTableB->getSize())
return false;
for (uint64_t Index = 0; Index < JumpTableA->Entries.size(); ++Index) {
const auto *LabelA = JumpTableA->Entries[Index];
const auto *LabelB = JumpTableB->Entries[Index];
const auto *TargetA = getBasicBlockForLabel(LabelA);
const auto *TargetB = BFB.getBasicBlockForLabel(LabelB);
if (!TargetA || !TargetB) {
assert((TargetA || LabelA == getFunctionEndLabel()) &&
"no target basic block found");
assert((TargetB || LabelB == BFB.getFunctionEndLabel()) &&
"no target basic block found");
if (TargetA != TargetB)
return false;
continue;
}
assert(TargetA && TargetB && "cannot locate target block(s)");
if (TargetA->getLayoutIndex() != TargetB->getLayoutIndex())
return false;
}
return true;
}
std::size_t BinaryFunction::hash(bool Recompute, bool UseDFS) const {
assert(hasCFG() && "function is expected to have CFG");
if (!Recompute)
return Hash;
const auto &Order = UseDFS ? dfs() : BasicBlocksLayout;
// The hash is computed by creating a string of all the opcodes
// in the function and hashing that string with std::hash.
std::string Opcodes;
for (const auto *BB : Order) {
for (const auto &Inst : *BB) {
unsigned Opcode = Inst.getOpcode();
if (BC.MII->get(Opcode).isPseudo())
continue;
// Ignore unconditional jumps since we check CFG consistency by processing
// basic blocks in order and do not rely on branches to be in-sync with
// CFG. Note that we still use condition code of conditional jumps.
if (BC.MIA->isUnconditionalBranch(Inst))
continue;
if (Opcode == 0) {
Opcodes.push_back(0);
continue;
}
while (Opcode) {
uint8_t LSB = Opcode & 0xff;
Opcodes.push_back(LSB);
Opcode = Opcode >> 8;
}
}
}
return Hash = std::hash<std::string>{}(Opcodes);
}
void BinaryFunction::insertBasicBlocks(
BinaryBasicBlock *Start,
std::vector<std::unique_ptr<BinaryBasicBlock>> &&NewBBs,
const bool UpdateLayout,
const bool UpdateCFIState) {
const auto StartIndex = getIndex(Start);
const auto NumNewBlocks = NewBBs.size();
BasicBlocks.insert(BasicBlocks.begin() + StartIndex + 1,
NumNewBlocks,
nullptr);
auto I = StartIndex + 1;
for (auto &BB : NewBBs) {
assert(!BasicBlocks[I]);
BasicBlocks[I++] = BB.release();
}
recomputeLandingPads();
if (UpdateLayout) {
updateLayout(Start, NumNewBlocks);
}
if (UpdateCFIState) {
updateCFIState(Start, NumNewBlocks);
}
}
BinaryFunction::iterator BinaryFunction::insertBasicBlocks(
BinaryFunction::iterator StartBB,
std::vector<std::unique_ptr<BinaryBasicBlock>> &&NewBBs,
const bool UpdateLayout,
const bool UpdateCFIState) {
const auto StartIndex = getIndex(&*StartBB);
const auto NumNewBlocks = NewBBs.size();
auto RetIter = BasicBlocks.insert(BasicBlocks.begin() + StartIndex + 1,
NumNewBlocks,
nullptr);
auto I = StartIndex + 1;
for (auto &BB : NewBBs) {
assert(!BasicBlocks[I]);
BasicBlocks[I++] = BB.release();
}
recomputeLandingPads();
if (UpdateLayout) {
updateLayout(*std::prev(RetIter), NumNewBlocks);
}
if (UpdateCFIState) {
updateCFIState(*std::prev(RetIter), NumNewBlocks);
}
return RetIter;
}
void BinaryFunction::updateBBIndices(const unsigned StartIndex) {
for (auto I = StartIndex; I < BasicBlocks.size(); ++I) {
BasicBlocks[I]->Index = I;
}
}
void BinaryFunction::updateCFIState(BinaryBasicBlock *Start,
const unsigned NumNewBlocks) {
const auto CFIState = Start->getCFIStateAtExit();
const auto StartIndex = getIndex(Start) + 1;
for (unsigned I = 0; I < NumNewBlocks; ++I) {
BasicBlocks[StartIndex + I]->setCFIState(CFIState);
}
}
void BinaryFunction::updateLayout(BinaryBasicBlock* Start,
const unsigned NumNewBlocks) {
// Insert new blocks in the layout immediately after Start.
auto Pos = std::find(layout_begin(), layout_end(), Start);
assert(Pos != layout_end());
auto Begin = &BasicBlocks[getIndex(Start) + 1];
auto End = &BasicBlocks[getIndex(Start) + NumNewBlocks + 1];
BasicBlocksLayout.insert(Pos + 1, Begin, End);
updateLayoutIndices();
}
bool BinaryFunction::replaceJumpTableEntryIn(BinaryBasicBlock *BB,
BinaryBasicBlock *OldDest,
BinaryBasicBlock *NewDest) {
auto *Instr = BB->getLastNonPseudoInstr();
if (!Instr || !BC.MIA->isIndirectBranch(*Instr))
return false;
auto JTAddress = BC.MIA->getJumpTable(*Instr);
assert(JTAddress && "Invalid jump table address");
auto *JT = getJumpTableContainingAddress(JTAddress);
assert(JT && "No jump table structure for this indirect branch");
bool Patched = JT->replaceDestination(JTAddress, OldDest->getLabel(),
NewDest->getLabel());
assert(Patched && "Invalid entry to be replaced in jump table");
return true;
}
BinaryBasicBlock *BinaryFunction::splitEdge(BinaryBasicBlock *From,
BinaryBasicBlock *To) {
// Create intermediate BB
MCSymbol *Tmp = BC.Ctx->createTempSymbol("SplitEdge", true);
auto NewBB = createBasicBlock(0, Tmp);
auto NewBBPtr = NewBB.get();
// Update "From" BB
auto I = From->succ_begin();
auto BI = From->branch_info_begin();
for (; I != From->succ_end(); ++I) {
if (*I == To)
break;
++BI;
}
assert(I != From->succ_end() && "Invalid CFG edge in splitEdge!");
uint64_t OrigCount{BI->Count};
uint64_t OrigMispreds{BI->MispredictedCount};
replaceJumpTableEntryIn(From, To, NewBBPtr);
From->replaceSuccessor(To, NewBBPtr, OrigCount, OrigMispreds);
NewBB->addSuccessor(To, OrigCount, OrigMispreds);
NewBB->setExecutionCount(OrigCount);
NewBB->setIsCold(From->isCold());
// Update CFI and BB layout with new intermediate BB
std::vector<std::unique_ptr<BinaryBasicBlock>> NewBBs;
NewBBs.emplace_back(std::move(NewBB));
insertBasicBlocks(From, std::move(NewBBs), true, true);
return NewBBPtr;
}
bool BinaryFunction::isDataMarker(const SymbolRef &Symbol,
uint64_t SymbolSize) const {
// For aarch64, the ABI defines mapping symbols so we identify data in the
// code section (see IHI0056B). $d identifies a symbol starting data contents.
if (BC.TheTriple->getArch() == llvm::Triple::aarch64 &&
Symbol.getType() == SymbolRef::ST_Unknown &&
SymbolSize == 0 &&
(!Symbol.getName().getError() && *Symbol.getName() == "$d"))
return true;
return false;
}
bool BinaryFunction::isCodeMarker(const SymbolRef &Symbol,
uint64_t SymbolSize) const {
// For aarch64, the ABI defines mapping symbols so we identify data in the
// code section (see IHI0056B). $x identifies a symbol starting code or the
// end of a data chunk inside code.
if (BC.TheTriple->getArch() == llvm::Triple::aarch64 &&
Symbol.getType() == SymbolRef::ST_Unknown &&
SymbolSize == 0 &&
(!Symbol.getName().getError() && *Symbol.getName() == "$x"))
return true;
return false;
}
bool BinaryFunction::isSymbolValidInScope(const SymbolRef &Symbol,
uint64_t SymbolSize) const {
// Some symbols are tolerated inside function bodies, others are not.
// The real function boundaries may not be known at this point.
if (isDataMarker(Symbol, SymbolSize) || isCodeMarker(Symbol, SymbolSize))
return true;
// It's okay to have a zero-sized symbol in the middle of non-zero-sized
// function.
if (SymbolSize == 0 && containsAddress(*Symbol.getAddress()))
return true;
if (Symbol.getType() != SymbolRef::ST_Unknown)
return false;
if (Symbol.getFlags() & SymbolRef::SF_Global)
return false;
return true;
}
SMLoc BinaryFunction::emitLineInfo(SMLoc NewLoc, SMLoc PrevLoc) const {
auto *FunctionCU = UnitLineTable.first;
const auto *FunctionLineTable = UnitLineTable.second;
assert(FunctionCU && "cannot emit line info for function without CU");
auto RowReference = DebugLineTableRowRef::fromSMLoc(NewLoc);
// Check if no new line info needs to be emitted.
if (RowReference == DebugLineTableRowRef::NULL_ROW ||
NewLoc.getPointer() == PrevLoc.getPointer())
return PrevLoc;
unsigned CurrentFilenum = 0;
const auto *CurrentLineTable = FunctionLineTable;
// If the CU id from the current instruction location does not
// match the CU id from the current function, it means that we
// have come across some inlined code. We must look up the CU
// for the instruction's original function and get the line table
// from that.
const auto FunctionUnitIndex = FunctionCU->getOffset();
const auto CurrentUnitIndex = RowReference.DwCompileUnitIndex;
if (CurrentUnitIndex != FunctionUnitIndex) {
CurrentLineTable = BC.DwCtx->getLineTableForUnit(
BC.DwCtx->getCompileUnitForOffset(CurrentUnitIndex));
// Add filename from the inlined function to the current CU.
CurrentFilenum =
BC.addDebugFilenameToUnit(FunctionUnitIndex, CurrentUnitIndex,
CurrentLineTable->Rows[RowReference.RowIndex - 1].File);
}
const auto &CurrentRow = CurrentLineTable->Rows[RowReference.RowIndex - 1];
if (!CurrentFilenum)
CurrentFilenum = CurrentRow.File;
BC.Ctx->setCurrentDwarfLoc(
CurrentFilenum,
CurrentRow.Line,
CurrentRow.Column,
(DWARF2_FLAG_IS_STMT * CurrentRow.IsStmt) |
(DWARF2_FLAG_BASIC_BLOCK * CurrentRow.BasicBlock) |
(DWARF2_FLAG_PROLOGUE_END * CurrentRow.PrologueEnd) |
(DWARF2_FLAG_EPILOGUE_BEGIN * CurrentRow.EpilogueBegin),
CurrentRow.Isa,
CurrentRow.Discriminator);
BC.Ctx->setDwarfCompileUnitID(FunctionUnitIndex);
return NewLoc;
}
BinaryFunction::~BinaryFunction() {
for (auto BB : BasicBlocks) {
delete BB;
}
for (auto BB : DeletedBasicBlocks) {
delete BB;
}
}
void BinaryFunction::emitJumpTables(MCStreamer *Streamer) {
if (JumpTables.empty())
return;
if (opts::PrintJumpTables) {
outs() << "BOLT-INFO: jump tables for function " << *this << ":\n";
}
for (auto &JTI : JumpTables) {
auto &JT = JTI.second;
if (opts::PrintJumpTables)
JT.print(outs());
if (opts::JumpTables == JTS_BASIC && BC.HasRelocations) {
JT.updateOriginal(BC);
} else {
MCSection *HotSection, *ColdSection;
if (opts::JumpTables == JTS_BASIC) {
JT.SectionName =
".local.JUMP_TABLEat0x" + Twine::utohexstr(JT.Address).str();
HotSection = BC.Ctx->getELFSection(JT.SectionName,
ELF::SHT_PROGBITS,
ELF::SHF_ALLOC);
ColdSection = HotSection;
} else {
HotSection = BC.MOFI->getReadOnlySection();
ColdSection = BC.MOFI->getReadOnlyColdSection();
}
JT.emit(Streamer, HotSection, ColdSection);
}
}
}
std::pair<size_t, size_t>
BinaryFunction::JumpTable::getEntriesForAddress(const uint64_t Addr) const {
const uint64_t InstOffset = Addr - Address;
size_t StartIndex = 0, EndIndex = 0;
uint64_t Offset = 0;
for (size_t I = 0; I < Entries.size(); ++I) {
auto LI = Labels.find(Offset);
if (LI != Labels.end()) {
const auto NextLI = std::next(LI);
const auto NextOffset =
NextLI == Labels.end() ? getSize() : NextLI->first;
if (InstOffset >= LI->first && InstOffset < NextOffset) {
StartIndex = I;
EndIndex = I;
while (Offset < NextOffset) {
++EndIndex;
Offset += EntrySize;
}
break;
}
}
Offset += EntrySize;
}
return std::make_pair(StartIndex, EndIndex);
}
bool BinaryFunction::JumpTable::replaceDestination(uint64_t JTAddress,
const MCSymbol *OldDest,
MCSymbol *NewDest) {
bool Patched{false};
const auto Range = getEntriesForAddress(JTAddress);
for (auto I = &Entries[Range.first], E = &Entries[Range.second];
I != E; ++I) {
auto &Entry = *I;
if (Entry == OldDest) {
Patched = true;
Entry = NewDest;
}
}
return Patched;
}
void BinaryFunction::JumpTable::updateOriginal(BinaryContext &BC) {
// In non-relocation mode we have to emit jump tables in local sections.
// This way we only overwrite them when a corresponding function is
// overwritten.
assert(BC.HasRelocations && "relocation mode expected");
auto SectionOrError = BC.getSectionForAddress(Address);
assert(SectionOrError && "section not found for jump table");
auto Section = SectionOrError.get();
uint64_t Offset = Address - Section.getAddress();
StringRef SectionName;
Section.getName(SectionName);
for (auto *Entry : Entries) {
const auto RelType = (Type == JTT_NORMAL) ? ELF::R_X86_64_64
: ELF::R_X86_64_PC32;
const uint64_t RelAddend = (Type == JTT_NORMAL)
? 0 : Offset - (Address - Section.getAddress());
DEBUG(dbgs() << "adding relocation to section " << SectionName
<< " at offset " << Twine::utohexstr(Offset) << " for symbol "
<< Entry->getName() << " with addend "
<< Twine::utohexstr(RelAddend) << '\n');
BC.addSectionRelocation(Section, Offset, Entry, RelType, RelAddend);
Offset += EntrySize;
}
}
uint64_t BinaryFunction::JumpTable::emit(MCStreamer *Streamer,
MCSection *HotSection,
MCSection *ColdSection) {
// Pre-process entries for aggressive splitting.
// Each label represents a separate switch table and gets its own count
// determining its destination.
std::map<MCSymbol *, uint64_t> LabelCounts;
if (opts::JumpTables > JTS_SPLIT && !Counts.empty()) {
MCSymbol *CurrentLabel = Labels[0];
uint64_t CurrentLabelCount = 0;
for (unsigned Index = 0; Index < Entries.size(); ++Index) {
auto LI = Labels.find(Index * EntrySize);
if (LI != Labels.end()) {
LabelCounts[CurrentLabel] = CurrentLabelCount;
CurrentLabel = LI->second;
CurrentLabelCount = 0;
}
CurrentLabelCount += Counts[Index].Count;
}
LabelCounts[CurrentLabel] = CurrentLabelCount;
} else {
Streamer->SwitchSection(Count > 0 ? HotSection : ColdSection);
Streamer->EmitValueToAlignment(EntrySize);
}
MCSymbol *LastLabel = nullptr;
uint64_t Offset = 0;
for (auto *Entry : Entries) {
auto LI = Labels.find(Offset);
if (LI != Labels.end()) {
DEBUG(dbgs() << "BOLT-DEBUG: emitting jump table "
<< LI->second->getName() << " (originally was at address 0x"
<< Twine::utohexstr(Address + Offset)
<< (Offset ? "as part of larger jump table\n" : "\n"));
if (!LabelCounts.empty()) {
DEBUG(dbgs() << "BOLT-DEBUG: jump table count: "
<< LabelCounts[LI->second] << '\n');
if (LabelCounts[LI->second] > 0) {
Streamer->SwitchSection(HotSection);
} else {
Streamer->SwitchSection(ColdSection);
}
Streamer->EmitValueToAlignment(EntrySize);
}
Streamer->EmitLabel(LI->second);
LastLabel = LI->second;
}
if (Type == JTT_NORMAL) {
Streamer->EmitSymbolValue(Entry, OutputEntrySize);
} else { // JTT_PIC
auto JT = MCSymbolRefExpr::create(LastLabel, Streamer->getContext());
auto E = MCSymbolRefExpr::create(Entry, Streamer->getContext());
auto Value = MCBinaryExpr::createSub(E, JT, Streamer->getContext());
Streamer->EmitValue(Value, EntrySize);
}
Offset += EntrySize;
}
return Offset;
}
void BinaryFunction::JumpTable::print(raw_ostream &OS) const {
uint64_t Offset = 0;
for (const auto *Entry : Entries) {
auto LI = Labels.find(Offset);
if (LI != Labels.end()) {
OS << "Jump Table " << LI->second->getName() << " at @0x"
<< Twine::utohexstr(Address+Offset);
if (Offset) {
OS << " (possibly part of larger jump table):\n";
} else {
OS << " with total count of " << Count << ":\n";
}
}
OS << format(" 0x%04" PRIx64 " : ", Offset) << Entry->getName();
if (!Counts.empty()) {
OS << " : " << Counts[Offset / EntrySize].Mispreds
<< "/" << Counts[Offset / EntrySize].Count;
}
OS << '\n';
Offset += EntrySize;
}
OS << "\n\n";
}
void BinaryFunction::calculateLoopInfo() {
// Discover loops.
BinaryDominatorTree DomTree(false);
DomTree.recalculate<BinaryFunction>(*this);
BLI.reset(new BinaryLoopInfo());
BLI->analyze(DomTree);
// Traverse discovered loops and add depth and profile information.
std::stack<BinaryLoop *> St;
for (auto I = BLI->begin(), E = BLI->end(); I != E; ++I) {
St.push(*I);
++BLI->OuterLoops;
}
while (!St.empty()) {
BinaryLoop *L = St.top();
St.pop();
++BLI->TotalLoops;
BLI->MaximumDepth = std::max(L->getLoopDepth(), BLI->MaximumDepth);
// Add nested loops in the stack.
for (BinaryLoop::iterator I = L->begin(), E = L->end(); I != E; ++I) {
St.push(*I);
}
// Skip if no valid profile is found.
if (!hasValidProfile()) {
L->EntryCount = COUNT_NO_PROFILE;
L->ExitCount = COUNT_NO_PROFILE;
L->TotalBackEdgeCount = COUNT_NO_PROFILE;
continue;
}
// Compute back edge count.
SmallVector<BinaryBasicBlock *, 1> Latches;
L->getLoopLatches(Latches);
for (BinaryBasicBlock *Latch : Latches) {
auto BI = Latch->branch_info_begin();
for (BinaryBasicBlock *Succ : Latch->successors()) {
if (Succ == L->getHeader()) {
assert(BI->Count != BinaryBasicBlock::COUNT_NO_PROFILE &&
"profile data not found");
L->TotalBackEdgeCount += BI->Count;
}
++BI;
}
}
// Compute entry count.
L->EntryCount = L->getHeader()->getExecutionCount() - L->TotalBackEdgeCount;
// Compute exit count.
SmallVector<BinaryLoop::Edge, 1> ExitEdges;
L->getExitEdges(ExitEdges);
for (BinaryLoop::Edge &Exit : ExitEdges) {
const BinaryBasicBlock *Exiting = Exit.first;
const BinaryBasicBlock *ExitTarget = Exit.second;
auto BI = Exiting->branch_info_begin();
for (BinaryBasicBlock *Succ : Exiting->successors()) {
if (Succ == ExitTarget) {
assert(BI->Count != BinaryBasicBlock::COUNT_NO_PROFILE &&
"profile data not found");
L->ExitCount += BI->Count;
}
++BI;
}
}
}
}
DWARFAddressRangesVector BinaryFunction::getOutputAddressRanges() const {
DWARFAddressRangesVector OutputRanges;
OutputRanges.emplace_back(getOutputAddress(),
getOutputAddress() + getOutputSize());
if (isSplit()) {
assert(isEmitted() && "split function should be emitted");
OutputRanges.emplace_back(cold().getAddress(),
cold().getAddress() + cold().getImageSize());
}
return OutputRanges;
}
uint64_t BinaryFunction::translateInputToOutputAddress(uint64_t Address) const {
// If the function hasn't changed return the same address.
if (!isEmitted() && !BC.HasRelocations)
return Address;
if (Address < getAddress())
return 0;
// FIXME: #18950828 - we rely on relative offsets inside basic blocks to stay
// intact. Instead we can use pseudo instructions and/or annotations.
const auto Offset = Address - getAddress();
const auto *BB = getBasicBlockContainingOffset(Offset);
if (!BB) {
// Special case for address immediately past the end of the function.
if (Offset == getSize())
return getOutputAddress() + getOutputSize();
return 0;
}
return std::min(BB->getOutputAddressRange().first + Offset - BB->getOffset(),
BB->getOutputAddressRange().second);
}
DWARFAddressRangesVector BinaryFunction::translateInputToOutputRanges(
const DWARFAddressRangesVector &InputRanges) const {
// If the function hasn't changed return the same ranges.
if (!isEmitted() && !BC.HasRelocations)
return InputRanges;
// Even though we will merge ranges in a post-processing pass, we attempt to
// merge them in a main processing loop as it improves the processing time.
uint64_t PrevEndAddress = 0;
DWARFAddressRangesVector OutputRanges;
for (const auto &Range : InputRanges) {
if (!containsAddress(Range.first)) {
DEBUG(dbgs() << "BOLT-DEBUG: invalid debug address range detected for "
<< *this << " : [0x" << Twine::utohexstr(Range.first)
<< ", 0x" << Twine::utohexstr(Range.second) << "]\n");
PrevEndAddress = 0;
continue;
}
auto InputOffset = Range.first - getAddress();
const auto InputEndOffset = std::min(Range.second - getAddress(), getSize());
auto BBI = std::upper_bound(BasicBlockOffsets.begin(),
BasicBlockOffsets.end(),
BasicBlockOffset(InputOffset, nullptr),
CompareBasicBlockOffsets());
--BBI;
do {
const auto *BB = BBI->second;
if (InputOffset < BB->getOffset() || InputOffset >= BB->getEndOffset()) {
DEBUG(dbgs() << "BOLT-DEBUG: invalid debug address range detected for "
<< *this << " : [0x" << Twine::utohexstr(Range.first)
<< ", 0x" << Twine::utohexstr(Range.second) << "]\n");
PrevEndAddress = 0;
break;
}
// Skip the range if the block was deleted.
if (const auto OutputStart = BB->getOutputAddressRange().first) {
const auto StartAddress = OutputStart + InputOffset - BB->getOffset();
auto EndAddress = BB->getOutputAddressRange().second;
if (InputEndOffset < BB->getEndOffset())
EndAddress = StartAddress + InputEndOffset - InputOffset;
if (StartAddress == PrevEndAddress) {
OutputRanges.back().second = std::max(OutputRanges.back().second,
EndAddress);
} else {
OutputRanges.emplace_back(StartAddress,
std::max(StartAddress, EndAddress));
}
PrevEndAddress = OutputRanges.back().second;
}
InputOffset = BB->getEndOffset();
++BBI;
} while (InputOffset < InputEndOffset);
}
// Post-processing pass to sort and merge ranges.
std::sort(OutputRanges.begin(), OutputRanges.end());
DWARFAddressRangesVector MergedRanges;
PrevEndAddress = 0;
for(const auto &Range : OutputRanges) {
if (Range.first <= PrevEndAddress) {
MergedRanges.back().second = std::max(MergedRanges.back().second,
Range.second);
} else {
MergedRanges.emplace_back(Range.first, Range.second);
}
PrevEndAddress = MergedRanges.back().second;
}
return MergedRanges;
}
MCInst *BinaryFunction::getInstructionAtOffset(uint64_t Offset) {
if (CurrentState == State::Disassembled) {
auto II = Instructions.find(Offset);
return (II == Instructions.end()) ? nullptr : &II->second;
} else if (CurrentState == State::CFG) {
auto *BB = getBasicBlockContainingOffset(Offset);
if (!BB)
return nullptr;
for (auto &Inst : *BB) {
constexpr auto InvalidOffset = std::numeric_limits<uint64_t>::max();
if (Offset == BC.MIA->getAnnotationWithDefault<uint64_t>(Inst, "Offset",
InvalidOffset))
return &Inst;
}
return nullptr;
} else {
llvm_unreachable("invalid CFG state to use getInstructionAtOffset()");
}
}
DWARFDebugLoc::LocationList BinaryFunction::translateInputToOutputLocationList(
const DWARFDebugLoc::LocationList &InputLL,
uint64_t BaseAddress) const {
// If the function wasn't changed - there's nothing to update.
if (!isEmitted() && !BC.HasRelocations) {
if (!BaseAddress) {
return InputLL;
} else {
auto OutputLL = std::move(InputLL);
for (auto &Entry : OutputLL.Entries) {
Entry.Begin += BaseAddress;
Entry.End += BaseAddress;
}
return OutputLL;
}
}
uint64_t PrevEndAddress = 0;
SmallVectorImpl<unsigned char> *PrevLoc = nullptr;
DWARFDebugLoc::LocationList OutputLL;
for (auto &Entry : InputLL.Entries) {
const auto Start = Entry.Begin + BaseAddress;
const auto End = Entry.End + BaseAddress;
if (!containsAddress(Start)) {
DEBUG(dbgs() << "BOLT-DEBUG: invalid debug address range detected for "
<< *this << " : [0x" << Twine::utohexstr(Start)
<< ", 0x" << Twine::utohexstr(End) << "]\n");
continue;
}
auto InputOffset = Start - getAddress();
const auto InputEndOffset = std::min(End - getAddress(), getSize());
auto BBI = std::upper_bound(BasicBlockOffsets.begin(),
BasicBlockOffsets.end(),
BasicBlockOffset(InputOffset, nullptr),
CompareBasicBlockOffsets());
--BBI;
do {
const auto *BB = BBI->second;
if (InputOffset < BB->getOffset() || InputOffset >= BB->getEndOffset()) {
DEBUG(dbgs() << "BOLT-DEBUG: invalid debug address range detected for "
<< *this << " : [0x" << Twine::utohexstr(Start)
<< ", 0x" << Twine::utohexstr(End) << "]\n");
PrevEndAddress = 0;
break;
}
// Skip the range if the block was deleted.
if (const auto OutputStart = BB->getOutputAddressRange().first) {
const auto StartAddress = OutputStart + InputOffset - BB->getOffset();
auto EndAddress = BB->getOutputAddressRange().second;
if (InputEndOffset < BB->getEndOffset())
EndAddress = StartAddress + InputEndOffset - InputOffset;
if (StartAddress == PrevEndAddress && Entry.Loc == *PrevLoc) {
OutputLL.Entries.back().End = std::max(OutputLL.Entries.back().End,
EndAddress);
} else {
OutputLL.Entries.emplace_back(
DWARFDebugLoc::Entry{StartAddress,
std::max(StartAddress, EndAddress),
Entry.Loc});
}
PrevEndAddress = OutputLL.Entries.back().End;
PrevLoc = &OutputLL.Entries.back().Loc;
}
++BBI;
InputOffset = BB->getEndOffset();
} while (InputOffset < InputEndOffset);
}
// Sort and merge adjacent entries with identical location.
std::stable_sort(OutputLL.Entries.begin(), OutputLL.Entries.end(),
[] (const DWARFDebugLoc::Entry &A, const DWARFDebugLoc::Entry &B) {
return A.Begin < B.Begin;
});
DWARFDebugLoc::LocationList MergedLL;
PrevEndAddress = 0;
PrevLoc = nullptr;
for(const auto &Entry : OutputLL.Entries) {
if (Entry.Begin <= PrevEndAddress && *PrevLoc == Entry.Loc) {
MergedLL.Entries.back().End = std::max(Entry.End,
MergedLL.Entries.back().End);
} else {
const auto Begin = std::max(Entry.Begin, PrevEndAddress);
const auto End = std::max(Begin, Entry.End);
MergedLL.Entries.emplace_back(DWARFDebugLoc::Entry{Begin,
End,
Entry.Loc});
}
PrevEndAddress = MergedLL.Entries.back().End;
PrevLoc = &MergedLL.Entries.back().Loc;
}
return MergedLL;
}
void BinaryFunction::printLoopInfo(raw_ostream &OS) const {
OS << "Loop Info for Function \"" << *this << "\"";
if (hasValidProfile()) {
OS << " (count: " << getExecutionCount() << ")";
}
OS << "\n";
std::stack<BinaryLoop *> St;
for (auto I = BLI->begin(), E = BLI->end(); I != E; ++I) {
St.push(*I);
}
while (!St.empty()) {
BinaryLoop *L = St.top();
St.pop();
for (BinaryLoop::iterator I = L->begin(), E = L->end(); I != E; ++I) {
St.push(*I);
}
if (!hasValidProfile())
continue;
OS << (L->getLoopDepth() > 1 ? "Nested" : "Outer") << " loop header: "
<< L->getHeader()->getName();
OS << "\n";
OS << "Loop basic blocks: ";
auto Sep = "";
for (auto BI = L->block_begin(), BE = L->block_end(); BI != BE; ++BI) {
OS << Sep << (*BI)->getName();
Sep = ", ";
}
OS << "\n";
if (hasValidProfile()) {
OS << "Total back edge count: " << L->TotalBackEdgeCount << "\n";
OS << "Loop entry count: " << L->EntryCount << "\n";
OS << "Loop exit count: " << L->ExitCount << "\n";
if (L->EntryCount > 0) {
OS << "Average iters per entry: "
<< format("%.4lf", (double)L->TotalBackEdgeCount / L->EntryCount)
<< "\n";
}
}
OS << "----\n";
}
OS << "Total number of loops: "<< BLI->TotalLoops << "\n";
OS << "Number of outer loops: " << BLI->OuterLoops << "\n";
OS << "Maximum nested loop depth: " << BLI->MaximumDepth << "\n\n";
}
DynoStats BinaryFunction::getDynoStats() const {
DynoStats Stats;
// Return empty-stats about the function we don't completely understand.
if (!isSimple() || !hasValidProfile())
return Stats;
// If the function was folded in non-relocation mode we keep its profile
// for optimization. However, it should be excluded from the dyno stats.
if (isFolded())
return Stats;
// Update enumeration of basic blocks for correct detection of branch'
// direction.
updateLayoutIndices();
for (const auto &BB : layout()) {
// The basic block execution count equals to the sum of incoming branch
// frequencies. This may deviate from the sum of outgoing branches of the
// basic block especially since the block may contain a function that
// does not return or a function that throws an exception.
const uint64_t BBExecutionCount = BB->getKnownExecutionCount();
// Ignore empty blocks and blocks that were not executed.
if (BB->getNumNonPseudos() == 0 || BBExecutionCount == 0)
continue;
// Count the number of calls by iterating through all instructions.
for (const auto &Instr : *BB) {
if (BC.MIA->isStore(Instr)) {
Stats[DynoStats::STORES] += BBExecutionCount;
}
if (BC.MIA->isLoad(Instr)) {
Stats[DynoStats::LOADS] += BBExecutionCount;
}
if (!BC.MIA->isCall(Instr))
continue;
uint64_t CallFreq = BBExecutionCount;
if (BC.MIA->getConditionalTailCall(Instr)) {
CallFreq =
BC.MIA->getAnnotationWithDefault<uint64_t>(Instr, "CTCTakenCount");
}
Stats[DynoStats::FUNCTION_CALLS] += CallFreq;
if (BC.MIA->isIndirectCall(Instr)) {
Stats[DynoStats::INDIRECT_CALLS] += CallFreq;
} else if (const auto *CallSymbol = BC.MIA->getTargetSymbol(Instr)) {
const auto *BF = BC.getFunctionForSymbol(CallSymbol);
if (BF && BF->isPLTFunction())
Stats[DynoStats::PLT_CALLS] += CallFreq;
// We don't process PLT functions and hence have to adjust
// relevant dynostats here.
Stats[DynoStats::LOADS] += CallFreq;
Stats[DynoStats::INDIRECT_CALLS] += CallFreq;
}
}
Stats[DynoStats::INSTRUCTIONS] += BB->getNumNonPseudos() * BBExecutionCount;
// Jump tables.
const auto *LastInstr = BB->getLastNonPseudoInstr();
if (BC.MIA->getJumpTable(*LastInstr)) {
Stats[DynoStats::JUMP_TABLE_BRANCHES] += BBExecutionCount;
DEBUG(
static uint64_t MostFrequentJT;
if (BBExecutionCount > MostFrequentJT) {
MostFrequentJT = BBExecutionCount;
dbgs() << "BOLT-INFO: most frequently executed jump table is in "
<< "function " << *this << " in basic block " << BB->getName()
<< " executed totally " << BBExecutionCount << " times.\n";
}
);
continue;
}
// Update stats for branches.
const MCSymbol *TBB = nullptr;
const MCSymbol *FBB = nullptr;
MCInst *CondBranch = nullptr;
MCInst *UncondBranch = nullptr;
if (!BB->analyzeBranch(TBB, FBB, CondBranch, UncondBranch)) {
continue;
}
if (!CondBranch && !UncondBranch) {
continue;
}
// Simple unconditional branch.
if (!CondBranch) {
Stats[DynoStats::UNCOND_BRANCHES] += BBExecutionCount;
continue;
}
// CTCs
if (BC.MIA->getConditionalTailCall(*CondBranch)) {
if (BB->branch_info_begin() != BB->branch_info_end())
Stats[DynoStats::UNCOND_BRANCHES] += BB->branch_info_begin()->Count;
continue;
}
// Conditional branch that could be followed by an unconditional branch.
uint64_t TakenCount = BB->getBranchInfo(true).Count;
if (TakenCount == COUNT_NO_PROFILE)
TakenCount = 0;
uint64_t NonTakenCount = BB->getBranchInfo(false).Count;
if (NonTakenCount == COUNT_NO_PROFILE)
NonTakenCount = 0;
if (isForwardBranch(BB, BB->getConditionalSuccessor(true))) {
Stats[DynoStats::FORWARD_COND_BRANCHES] += BBExecutionCount;
Stats[DynoStats::FORWARD_COND_BRANCHES_TAKEN] += TakenCount;
} else {
Stats[DynoStats::BACKWARD_COND_BRANCHES] += BBExecutionCount;
Stats[DynoStats::BACKWARD_COND_BRANCHES_TAKEN] += TakenCount;
}
if (UncondBranch) {
Stats[DynoStats::UNCOND_BRANCHES] += NonTakenCount;
}
}
return Stats;
}
void DynoStats::print(raw_ostream &OS, const DynoStats *Other) const {
auto printStatWithDelta = [&](const std::string &Name, uint64_t Stat,
uint64_t OtherStat) {
OS << format("%'20lld : ", Stat * opts::DynoStatsScale) << Name;
if (Other) {
if (Stat != OtherStat) {
OtherStat = std::max(OtherStat, uint64_t(1)); // to prevent divide by 0
OS << format(" (%+.1f%%)",
( (float) Stat - (float) OtherStat ) * 100.0 /
(float) (OtherStat) );
} else {
OS << " (=)";
}
}
OS << '\n';
};
for (auto Stat = DynoStats::FIRST_DYNO_STAT + 1;
Stat < DynoStats::LAST_DYNO_STAT;
++Stat) {
printStatWithDelta(Desc[Stat], Stats[Stat], Other ? (*Other)[Stat] : 0);
}
}
void DynoStats::operator+=(const DynoStats &Other) {
for (auto Stat = DynoStats::FIRST_DYNO_STAT + 1;
Stat < DynoStats::LAST_DYNO_STAT;
++Stat) {
Stats[Stat] += Other[Stat];
}
}
} // namespace bolt
} // namespace llvm
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