/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/llvm/include/llvm/Support/Alignment.h

Bug Summary

File:	llvm/include/llvm/Support/Alignment.h
Warning:	line 85, column 47 The result of the left shift is undefined due to shifting by '255', which is greater or equal to the width of type 'uint64_t'

Annotated Source Code

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clang -cc1 -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name MCAssembler.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mframe-pointer=none -fmath-errno -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -ffunction-sections -fdata-sections -fcoverage-compilation-dir=/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/lib/MC -resource-dir /usr/lib/llvm-14/lib/clang/14.0.0 -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/lib/MC -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/llvm/lib/MC -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/include -I /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/llvm/include -D NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/x86_64-linux-gnu/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/backward -internal-isystem /usr/lib/llvm-14/lib/clang/14.0.0/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-class-memaccess -Wno-redundant-move -Wno-pessimizing-move -Wno-noexcept-type -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir=/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/build-llvm/lib/MC -fdebug-prefix-map=/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e=. -ferror-limit 19 -fvisibility-inlines-hidden -stack-protector 2 -fgnuc-version=4.2.1 -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/scan-build-2021-09-04-040900-46481-1 -x c++ /build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/llvm/lib/MC/MCAssembler.cpp

/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/llvm/lib/MC/MCAssembler.cpp

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1//===- lib/MC/MCAssembler.cpp - Assembler Backend Implementation ----------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//

9#include "llvm/MC/MCAssembler.h"
10#include "llvm/ADT/ArrayRef.h"
11#include "llvm/ADT/SmallString.h"
12#include "llvm/ADT/SmallVector.h"
13#include "llvm/ADT/Statistic.h"
14#include "llvm/ADT/StringRef.h"
15#include "llvm/ADT/Twine.h"
16#include "llvm/MC/MCAsmBackend.h"
17#include "llvm/MC/MCAsmInfo.h"
18#include "llvm/MC/MCAsmLayout.h"
19#include "llvm/MC/MCCodeEmitter.h"
20#include "llvm/MC/MCCodeView.h"
21#include "llvm/MC/MCContext.h"
22#include "llvm/MC/MCDwarf.h"
23#include "llvm/MC/MCExpr.h"
24#include "llvm/MC/MCFixup.h"
25#include "llvm/MC/MCFixupKindInfo.h"
26#include "llvm/MC/MCFragment.h"
27#include "llvm/MC/MCInst.h"
28#include "llvm/MC/MCObjectWriter.h"
29#include "llvm/MC/MCSection.h"
30#include "llvm/MC/MCSectionELF.h"
31#include "llvm/MC/MCSymbol.h"
32#include "llvm/MC/MCValue.h"
33#include "llvm/Support/Alignment.h"
34#include "llvm/Support/Casting.h"
35#include "llvm/Support/Debug.h"
36#include "llvm/Support/EndianStream.h"
37#include "llvm/Support/ErrorHandling.h"
38#include "llvm/Support/LEB128.h"
39#include "llvm/Support/MathExtras.h"
40#include "llvm/Support/raw_ostream.h"
41#include <cassert>
42#include <cstdint>
43#include <cstring>
44#include <tuple>
45#include <utility>

47using namespace llvm;

49#define DEBUG_TYPE"assembler" "assembler"

51namespace {
52namespace stats {

54STATISTIC(EmittedFragments, "Number of emitted assembler fragments - total")static llvm::Statistic EmittedFragments = {"assembler", "EmittedFragments"
, "Number of emitted assembler fragments - total"};
55STATISTIC(EmittedRelaxableFragments,static llvm::Statistic EmittedRelaxableFragments = {"assembler"
, "EmittedRelaxableFragments", "Number of emitted assembler fragments - relaxable"
}
        "Number of emitted assembler fragments - relaxable")static llvm::Statistic EmittedRelaxableFragments = {"assembler"
, "EmittedRelaxableFragments", "Number of emitted assembler fragments - relaxable"
};
57STATISTIC(EmittedDataFragments,static llvm::Statistic EmittedDataFragments = {"assembler", "EmittedDataFragments"
, "Number of emitted assembler fragments - data"}
        "Number of emitted assembler fragments - data")static llvm::Statistic EmittedDataFragments = {"assembler", "EmittedDataFragments"
, "Number of emitted assembler fragments - data"};
59STATISTIC(EmittedCompactEncodedInstFragments,static llvm::Statistic EmittedCompactEncodedInstFragments = {
"assembler", "EmittedCompactEncodedInstFragments", "Number of emitted assembler fragments - compact encoded inst"
}
        "Number of emitted assembler fragments - compact encoded inst")static llvm::Statistic EmittedCompactEncodedInstFragments = {
"assembler", "EmittedCompactEncodedInstFragments", "Number of emitted assembler fragments - compact encoded inst"
};
61STATISTIC(EmittedAlignFragments,static llvm::Statistic EmittedAlignFragments = {"assembler", "EmittedAlignFragments"
, "Number of emitted assembler fragments - align"}
        "Number of emitted assembler fragments - align")static llvm::Statistic EmittedAlignFragments = {"assembler", "EmittedAlignFragments"
, "Number of emitted assembler fragments - align"};
63STATISTIC(EmittedFillFragments,static llvm::Statistic EmittedFillFragments = {"assembler", "EmittedFillFragments"
, "Number of emitted assembler fragments - fill"}
        "Number of emitted assembler fragments - fill")static llvm::Statistic EmittedFillFragments = {"assembler", "EmittedFillFragments"
, "Number of emitted assembler fragments - fill"};
65STATISTIC(EmittedNopsFragments, "Number of emitted assembler fragments - nops")static llvm::Statistic EmittedNopsFragments = {"assembler", "EmittedNopsFragments"
, "Number of emitted assembler fragments - nops"};
66STATISTIC(EmittedOrgFragments, "Number of emitted assembler fragments - org")static llvm::Statistic EmittedOrgFragments = {"assembler", "EmittedOrgFragments"
, "Number of emitted assembler fragments - org"};
67STATISTIC(evaluateFixup, "Number of evaluated fixups")static llvm::Statistic evaluateFixup = {"assembler", "evaluateFixup"
, "Number of evaluated fixups"};
68STATISTIC(FragmentLayouts, "Number of fragment layouts")static llvm::Statistic FragmentLayouts = {"assembler", "FragmentLayouts"
, "Number of fragment layouts"};
69STATISTIC(ObjectBytes, "Number of emitted object file bytes")static llvm::Statistic ObjectBytes = {"assembler", "ObjectBytes"
, "Number of emitted object file bytes"};
70STATISTIC(RelaxationSteps, "Number of assembler layout and relaxation steps")static llvm::Statistic RelaxationSteps = {"assembler", "RelaxationSteps"
, "Number of assembler layout and relaxation steps"};
71STATISTIC(RelaxedInstructions, "Number of relaxed instructions")static llvm::Statistic RelaxedInstructions = {"assembler", "RelaxedInstructions"
, "Number of relaxed instructions"};

73} // end namespace stats
74} // end anonymous namespace

76// FIXME FIXME FIXME: There are number of places in this file where we convert
77// what is a 64-bit assembler value used for computation into a value in the
78// object file, which may truncate it. We should detect that truncation where
79// invalid and report errors back.

81/* *** */

83MCAssembler::MCAssembler(MCContext &Context,
                       std::unique_ptr<MCAsmBackend> Backend,
                       std::unique_ptr<MCCodeEmitter> Emitter,
                       std::unique_ptr<MCObjectWriter> Writer)
  : Context(Context), Backend(std::move(Backend)),
    Emitter(std::move(Emitter)), Writer(std::move(Writer)),
    BundleAlignSize(0), RelaxAll(false), SubsectionsViaSymbols(false),
    IncrementalLinkerCompatible(false), ELFHeaderEFlags(0) {
VersionInfo.Major = 0; // Major version == 0 for "none specified"
92}

94MCAssembler::~MCAssembler() = default;

96void MCAssembler::reset() {
Sections.clear();
Symbols.clear();
IndirectSymbols.clear();
DataRegions.clear();
LinkerOptions.clear();
FileNames.clear();
ThumbFuncs.clear();
BundleAlignSize = 0;
RelaxAll = false;
SubsectionsViaSymbols = false;
IncrementalLinkerCompatible = false;
ELFHeaderEFlags = 0;
LOHContainer.reset();
VersionInfo.Major = 0;
VersionInfo.SDKVersion = VersionTuple();

// reset objects owned by us
if (getBackendPtr())
  getBackendPtr()->reset();
if (getEmitterPtr())
  getEmitterPtr()->reset();
if (getWriterPtr())
  getWriterPtr()->reset();
getLOHContainer().reset();
121}

123bool MCAssembler::registerSection(MCSection &Section) {
if (Section.isRegistered())
  return false;
Sections.push_back(&Section);
Section.setIsRegistered(true);
return true;
129}

131bool MCAssembler::isThumbFunc(const MCSymbol *Symbol) const {
if (ThumbFuncs.count(Symbol))
  return true;

if (!Symbol->isVariable())
  return false;

const MCExpr *Expr = Symbol->getVariableValue();

MCValue V;
if (!Expr->evaluateAsRelocatable(V, nullptr, nullptr))
  return false;

if (V.getSymB() || V.getRefKind() != MCSymbolRefExpr::VK_None)
  return false;

const MCSymbolRefExpr *Ref = V.getSymA();
if (!Ref)
  return false;

if (Ref->getKind() != MCSymbolRefExpr::VK_None)
  return false;

const MCSymbol &Sym = Ref->getSymbol();
if (!isThumbFunc(&Sym))
  return false;

ThumbFuncs.insert(Symbol); // Cache it.
return true;
160}

162bool MCAssembler::isSymbolLinkerVisible(const MCSymbol &Symbol) const {
// Non-temporary labels should always be visible to the linker.
if (!Symbol.isTemporary())
  return true;

if (Symbol.isUsedInReloc())
  return true;

return false;
171}

173const MCSymbol *MCAssembler::getAtom(const MCSymbol &S) const {
// Linker visible symbols define atoms.
if (isSymbolLinkerVisible(S))
  return &S;

// Absolute and undefined symbols have no defining atom.
if (!S.isInSection())
  return nullptr;

// Non-linker visible symbols in sections which can't be atomized have no
// defining atom.
if (!getContext().getAsmInfo()->isSectionAtomizableBySymbols(
        *S.getFragment()->getParent()))
  return nullptr;

// Otherwise, return the atom for the containing fragment.
return S.getFragment()->getAtom();
190}

192bool MCAssembler::evaluateFixup(const MCAsmLayout &Layout,
                              const MCFixup &Fixup, const MCFragment *DF,
                              MCValue &Target, uint64_t &Value,
                              bool &WasForced) const {
++stats::evaluateFixup;

// FIXME: This code has some duplication with recordRelocation. We should
// probably merge the two into a single callback that tries to evaluate a
// fixup and records a relocation if one is needed.

// On error claim to have completely evaluated the fixup, to prevent any
// further processing from being done.
const MCExpr *Expr = Fixup.getValue();
MCContext &Ctx = getContext();
Value = 0;
WasForced = false;
if (!Expr->evaluateAsRelocatable(Target, &Layout, &Fixup)) {
  Ctx.reportError(Fixup.getLoc(), "expected relocatable expression");
  return true;
}
if (const MCSymbolRefExpr *RefB = Target.getSymB()) {
  if (RefB->getKind() != MCSymbolRefExpr::VK_None) {
    Ctx.reportError(Fixup.getLoc(),
                    "unsupported subtraction of qualified symbol");
    return true;
  }
}

assert(getBackendPtr() && "Expected assembler backend")(static_cast<void> (0));
bool IsTarget = getBackendPtr()->getFixupKindInfo(Fixup.getKind()).Flags &
                MCFixupKindInfo::FKF_IsTarget;

if (IsTarget)
  return getBackend().evaluateTargetFixup(*this, Layout, Fixup, DF, Target,
                                          Value, WasForced);

unsigned FixupFlags = getBackendPtr()->getFixupKindInfo(Fixup.getKind()).Flags;
bool IsPCRel = getBackendPtr()->getFixupKindInfo(Fixup.getKind()).Flags &
               MCFixupKindInfo::FKF_IsPCRel;

bool IsResolved = false;
if (IsPCRel) {
  if (Target.getSymB()) {
    IsResolved = false;
  } else if (!Target.getSymA()) {
    IsResolved = false;
  } else {
    const MCSymbolRefExpr *A = Target.getSymA();
    const MCSymbol &SA = A->getSymbol();
    if (A->getKind() != MCSymbolRefExpr::VK_None || SA.isUndefined()) {
      IsResolved = false;
    } else if (auto *Writer = getWriterPtr()) {
      IsResolved = (FixupFlags & MCFixupKindInfo::FKF_Constant) ||
                   Writer->isSymbolRefDifferenceFullyResolvedImpl(
                       *this, SA, *DF, false, true);
    }
  }
} else {
  IsResolved = Target.isAbsolute();
}

Value = Target.getConstant();

if (const MCSymbolRefExpr *A = Target.getSymA()) {
  const MCSymbol &Sym = A->getSymbol();
  if (Sym.isDefined())
    Value += Layout.getSymbolOffset(Sym);
}
if (const MCSymbolRefExpr *B = Target.getSymB()) {
  const MCSymbol &Sym = B->getSymbol();
  if (Sym.isDefined())
    Value -= Layout.getSymbolOffset(Sym);
}

bool ShouldAlignPC = getBackend().getFixupKindInfo(Fixup.getKind()).Flags &
                     MCFixupKindInfo::FKF_IsAlignedDownTo32Bits;
assert((ShouldAlignPC ? IsPCRel : true) &&(static_cast<void> (0))
  "FKF_IsAlignedDownTo32Bits is only allowed on PC-relative fixups!")(static_cast<void> (0));

if (IsPCRel) {
  uint32_t Offset = Layout.getFragmentOffset(DF) + Fixup.getOffset();

  // A number of ARM fixups in Thumb mode require that the effective PC
  // address be determined as the 32-bit aligned version of the actual offset.
  if (ShouldAlignPC) Offset &= ~0x3;
  Value -= Offset;
}

// Let the backend force a relocation if needed.
if (IsResolved && getBackend().shouldForceRelocation(*this, Fixup, Target)) {
  IsResolved = false;
  WasForced = true;
}

return IsResolved;
287}

289uint64_t MCAssembler::computeFragmentSize(const MCAsmLayout &Layout,
                                        const MCFragment &F) const {
assert(getBackendPtr() && "Requires assembler backend")(static_cast<void> (0));
switch (F.getKind()) {
13
←
Control jumps to 'case FT_Align:'  at line 327→
case MCFragment::FT_Data:
  return cast<MCDataFragment>(F).getContents().size();
case MCFragment::FT_Relaxable:
  return cast<MCRelaxableFragment>(F).getContents().size();
case MCFragment::FT_CompactEncodedInst:
  return cast<MCCompactEncodedInstFragment>(F).getContents().size();
case MCFragment::FT_Fill: {
  auto &FF = cast<MCFillFragment>(F);
  int64_t NumValues = 0;
  if (!FF.getNumValues().evaluateAsAbsolute(NumValues, Layout)) {
    getContext().reportError(FF.getLoc(),
                             "expected assembly-time absolute expression");
    return 0;
  }
  int64_t Size = NumValues * FF.getValueSize();
  if (Size < 0) {
    getContext().reportError(FF.getLoc(), "invalid number of bytes");
    return 0;
  }
  return Size;
}

case MCFragment::FT_Nops:
  return cast<MCNopsFragment>(F).getNumBytes();

case MCFragment::FT_LEB:
  return cast<MCLEBFragment>(F).getContents().size();

case MCFragment::FT_BoundaryAlign:
  return cast<MCBoundaryAlignFragment>(F).getSize();

case MCFragment::FT_SymbolId:
  return 4;

case MCFragment::FT_Align: {
  const MCAlignFragment &AF = cast<MCAlignFragment>(F);
14
←
'F' is a 'MCAlignFragment'→
  unsigned Offset = Layout.getFragmentOffset(&AF);
  unsigned Size = offsetToAlignment(Offset, Align(AF.getAlignment()));
15
←
Calling 'offsetToAlignment'→

  // Insert extra Nops for code alignment if the target define
  // shouldInsertExtraNopBytesForCodeAlign target hook.
  if (AF.getParent()->UseCodeAlign() && AF.hasEmitNops() &&
      getBackend().shouldInsertExtraNopBytesForCodeAlign(AF, Size))
    return Size;

  // If we are padding with nops, force the padding to be larger than the
  // minimum nop size.
  if (Size > 0 && AF.hasEmitNops()) {
    while (Size % getBackend().getMinimumNopSize())
      Size += AF.getAlignment();
  }
  if (Size > AF.getMaxBytesToEmit())
    return 0;
  return Size;
}

case MCFragment::FT_Org: {
  const MCOrgFragment &OF = cast<MCOrgFragment>(F);
  MCValue Value;
  if (!OF.getOffset().evaluateAsValue(Value, Layout)) {
    getContext().reportError(OF.getLoc(),
                             "expected assembly-time absolute expression");
      return 0;
  }

  uint64_t FragmentOffset = Layout.getFragmentOffset(&OF);
  int64_t TargetLocation = Value.getConstant();
  if (const MCSymbolRefExpr *A = Value.getSymA()) {
    uint64_t Val;
    if (!Layout.getSymbolOffset(A->getSymbol(), Val)) {
      getContext().reportError(OF.getLoc(), "expected absolute expression");
      return 0;
    }
    TargetLocation += Val;
  }
  int64_t Size = TargetLocation - FragmentOffset;
  if (Size < 0 || Size >= 0x40000000) {
    getContext().reportError(
        OF.getLoc(), "invalid .org offset '" + Twine(TargetLocation) +
                         "' (at offset '" + Twine(FragmentOffset) + "')");
    return 0;
  }
  return Size;
}

case MCFragment::FT_Dwarf:
  return cast<MCDwarfLineAddrFragment>(F).getContents().size();
case MCFragment::FT_DwarfFrame:
  return cast<MCDwarfCallFrameFragment>(F).getContents().size();
case MCFragment::FT_CVInlineLines:
  return cast<MCCVInlineLineTableFragment>(F).getContents().size();
case MCFragment::FT_CVDefRange:
  return cast<MCCVDefRangeFragment>(F).getContents().size();
case MCFragment::FT_PseudoProbe:
  return cast<MCPseudoProbeAddrFragment>(F).getContents().size();
case MCFragment::FT_Dummy:
  llvm_unreachable("Should not have been added")__builtin_unreachable();
}

llvm_unreachable("invalid fragment kind")__builtin_unreachable();
393}

395void MCAsmLayout::layoutFragment(MCFragment *F) {
MCFragment *Prev = F->getPrevNode();

// We should never try to recompute something which is valid.
assert(!isFragmentValid(F) && "Attempt to recompute a valid fragment!")(static_cast<void> (0));
// We should never try to compute the fragment layout if its predecessor
// isn't valid.
assert((!Prev || isFragmentValid(Prev)) &&(static_cast<void> (0))
       "Attempt to compute fragment before its predecessor!")(static_cast<void> (0));

assert(!F->IsBeingLaidOut && "Already being laid out!")(static_cast<void> (0));
F->IsBeingLaidOut = true;

++stats::FragmentLayouts;

// Compute fragment offset and size.
if (Prev)
  F->Offset = Prev->Offset + getAssembler().computeFragmentSize(*this, *Prev);
else
  F->Offset = 0;
F->IsBeingLaidOut = false;
LastValidFragment[F->getParent()] = F;

// If bundling is enabled and this fragment has instructions in it, it has to
// obey the bundling restrictions. With padding, we'll have:
//
//
//        BundlePadding
//             |||
// -------------------------------------
//   Prev  |##########|       F        |
// -------------------------------------
//                    ^
//                    |
//                    F->Offset
//
// The fragment's offset will point to after the padding, and its computed
// size won't include the padding.
//
// When the -mc-relax-all flag is used, we optimize bundling by writting the
// padding directly into fragments when the instructions are emitted inside
// the streamer. When the fragment is larger than the bundle size, we need to
// ensure that it's bundle aligned. This means that if we end up with
// multiple fragments, we must emit bundle padding between fragments.
//
// ".align N" is an example of a directive that introduces multiple
// fragments. We could add a special case to handle ".align N" by emitting
// within-fragment padding (which would produce less padding when N is less
// than the bundle size), but for now we don't.
//
if (Assembler.isBundlingEnabled() && F->hasInstructions()) {
  assert(isa<MCEncodedFragment>(F) &&(static_cast<void> (0))
         "Only MCEncodedFragment implementations have instructions")(static_cast<void> (0));
  MCEncodedFragment *EF = cast<MCEncodedFragment>(F);
  uint64_t FSize = Assembler.computeFragmentSize(*this, *EF);

  if (!Assembler.getRelaxAll() && FSize > Assembler.getBundleAlignSize())
    report_fatal_error("Fragment can't be larger than a bundle size");

  uint64_t RequiredBundlePadding =
      computeBundlePadding(Assembler, EF, EF->Offset, FSize);
  if (RequiredBundlePadding > UINT8_MAX(255))
    report_fatal_error("Padding cannot exceed 255 bytes");
  EF->setBundlePadding(static_cast<uint8_t>(RequiredBundlePadding));
  EF->Offset += RequiredBundlePadding;
}
461}

463void MCAssembler::registerSymbol(const MCSymbol &Symbol, bool *Created) {
bool New = !Symbol.isRegistered();
if (Created)
  *Created = New;
if (New) {
  Symbol.setIsRegistered(true);
  Symbols.push_back(&Symbol);
}
471}

473void MCAssembler::writeFragmentPadding(raw_ostream &OS,
                                     const MCEncodedFragment &EF,
                                     uint64_t FSize) const {
assert(getBackendPtr() && "Expected assembler backend")(static_cast<void> (0));
// Should NOP padding be written out before this fragment?
unsigned BundlePadding = EF.getBundlePadding();
if (BundlePadding > 0) {
  assert(isBundlingEnabled() &&(static_cast<void> (0))
         "Writing bundle padding with disabled bundling")(static_cast<void> (0));
  assert(EF.hasInstructions() &&(static_cast<void> (0))
         "Writing bundle padding for a fragment without instructions")(static_cast<void> (0));

  unsigned TotalLength = BundlePadding + static_cast<unsigned>(FSize);
  if (EF.alignToBundleEnd() && TotalLength > getBundleAlignSize()) {
    // If the padding itself crosses a bundle boundary, it must be emitted
    // in 2 pieces, since even nop instructions must not cross boundaries.
    //             v--------------v   <- BundleAlignSize
    //        v---------v             <- BundlePadding
    // ----------------------------
    // | Prev |####|####|    F    |
    // ----------------------------
    //        ^-------------------^   <- TotalLength
    unsigned DistanceToBoundary = TotalLength - getBundleAlignSize();
    if (!getBackend().writeNopData(OS, DistanceToBoundary))
      report_fatal_error("unable to write NOP sequence of " +
                         Twine(DistanceToBoundary) + " bytes");
    BundlePadding -= DistanceToBoundary;
  }
  if (!getBackend().writeNopData(OS, BundlePadding))
    report_fatal_error("unable to write NOP sequence of " +
                       Twine(BundlePadding) + " bytes");
}
505}

507/// Write the fragment \p F to the output file.
508static void writeFragment(raw_ostream &OS, const MCAssembler &Asm,
                        const MCAsmLayout &Layout, const MCFragment &F) {
// FIXME: Embed in fragments instead?
uint64_t FragmentSize = Asm.computeFragmentSize(Layout, F);

support::endianness Endian = Asm.getBackend().Endian;

if (const MCEncodedFragment *EF = dyn_cast<MCEncodedFragment>(&F))
  Asm.writeFragmentPadding(OS, *EF, FragmentSize);

// This variable (and its dummy usage) is to participate in the assert at
// the end of the function.
uint64_t Start = OS.tell();
(void) Start;

++stats::EmittedFragments;

switch (F.getKind()) {
case MCFragment::FT_Align: {
  ++stats::EmittedAlignFragments;
  const MCAlignFragment &AF = cast<MCAlignFragment>(F);
  assert(AF.getValueSize() && "Invalid virtual align in concrete fragment!")(static_cast<void> (0));

  uint64_t Count = FragmentSize / AF.getValueSize();

  // FIXME: This error shouldn't actually occur (the front end should emit
  // multiple .align directives to enforce the semantics it wants), but is
  // severe enough that we want to report it. How to handle this?
  if (Count * AF.getValueSize() != FragmentSize)
    report_fatal_error("undefined .align directive, value size '" +
                      Twine(AF.getValueSize()) +
                      "' is not a divisor of padding size '" +
                      Twine(FragmentSize) + "'");

  // See if we are aligning with nops, and if so do that first to try to fill
  // the Count bytes.  Then if that did not fill any bytes or there are any
  // bytes left to fill use the Value and ValueSize to fill the rest.
  // If we are aligning with nops, ask that target to emit the right data.
  if (AF.hasEmitNops()) {
    if (!Asm.getBackend().writeNopData(OS, Count))
      report_fatal_error("unable to write nop sequence of " +
                        Twine(Count) + " bytes");
    break;
  }

  // Otherwise, write out in multiples of the value size.
  for (uint64_t i = 0; i != Count; ++i) {
    switch (AF.getValueSize()) {
    default: llvm_unreachable("Invalid size!")__builtin_unreachable();
    case 1: OS << char(AF.getValue()); break;
    case 2:
      support::endian::write<uint16_t>(OS, AF.getValue(), Endian);
      break;
    case 4:
      support::endian::write<uint32_t>(OS, AF.getValue(), Endian);
      break;
    case 8:
      support::endian::write<uint64_t>(OS, AF.getValue(), Endian);
      break;
    }
  }
  break;
}

case MCFragment::FT_Data:
  ++stats::EmittedDataFragments;
  OS << cast<MCDataFragment>(F).getContents();
  break;

case MCFragment::FT_Relaxable:
  ++stats::EmittedRelaxableFragments;
  OS << cast<MCRelaxableFragment>(F).getContents();
  break;

case MCFragment::FT_CompactEncodedInst:
  ++stats::EmittedCompactEncodedInstFragments;
  OS << cast<MCCompactEncodedInstFragment>(F).getContents();
  break;

case MCFragment::FT_Fill: {
  ++stats::EmittedFillFragments;
  const MCFillFragment &FF = cast<MCFillFragment>(F);
  uint64_t V = FF.getValue();
  unsigned VSize = FF.getValueSize();
  const unsigned MaxChunkSize = 16;
  char Data[MaxChunkSize];
  assert(0 < VSize && VSize <= MaxChunkSize && "Illegal fragment fill size")(static_cast<void> (0));
  // Duplicate V into Data as byte vector to reduce number of
  // writes done. As such, do endian conversion here.
  for (unsigned I = 0; I != VSize; ++I) {
    unsigned index = Endian == support::little ? I : (VSize - I - 1);
    Data[I] = uint8_t(V >> (index * 8));
  }
  for (unsigned I = VSize; I < MaxChunkSize; ++I)
    Data[I] = Data[I - VSize];

  // Set to largest multiple of VSize in Data.
  const unsigned NumPerChunk = MaxChunkSize / VSize;
  // Set ChunkSize to largest multiple of VSize in Data
  const unsigned ChunkSize = VSize * NumPerChunk;

  // Do copies by chunk.
  StringRef Ref(Data, ChunkSize);
  for (uint64_t I = 0, E = FragmentSize / ChunkSize; I != E; ++I)
    OS << Ref;

  // do remainder if needed.
  unsigned TrailingCount = FragmentSize % ChunkSize;
  if (TrailingCount)
    OS.write(Data, TrailingCount);
  break;
}

case MCFragment::FT_Nops: {
  ++stats::EmittedNopsFragments;
  const MCNopsFragment &NF = cast<MCNopsFragment>(F);
  int64_t NumBytes = NF.getNumBytes();
  int64_t ControlledNopLength = NF.getControlledNopLength();
  int64_t MaximumNopLength = Asm.getBackend().getMaximumNopSize();

  assert(NumBytes > 0 && "Expected positive NOPs fragment size")(static_cast<void> (0));
  assert(ControlledNopLength >= 0 && "Expected non-negative NOP size")(static_cast<void> (0));

  if (ControlledNopLength > MaximumNopLength) {
    Asm.getContext().reportError(NF.getLoc(),
                                 "illegal NOP size " +
                                     std::to_string(ControlledNopLength) +
                                     ". (expected within [0, " +
                                     std::to_string(MaximumNopLength) + "])");
    // Clamp the NOP length as reportError does not stop the execution
    // immediately.
    ControlledNopLength = MaximumNopLength;
  }

  // Use maximum value if the size of each NOP is not specified
  if (!ControlledNopLength)
    ControlledNopLength = MaximumNopLength;

  while (NumBytes) {
    uint64_t NumBytesToEmit =
        (uint64_t)std::min(NumBytes, ControlledNopLength);
    assert(NumBytesToEmit && "try to emit empty NOP instruction")(static_cast<void> (0));
    if (!Asm.getBackend().writeNopData(OS, NumBytesToEmit)) {
      report_fatal_error("unable to write nop sequence of the remaining " +
                         Twine(NumBytesToEmit) + " bytes");
      break;
    }
    NumBytes -= NumBytesToEmit;
  }
  break;
}

case MCFragment::FT_LEB: {
  const MCLEBFragment &LF = cast<MCLEBFragment>(F);
  OS << LF.getContents();
  break;
}

case MCFragment::FT_BoundaryAlign: {
  if (!Asm.getBackend().writeNopData(OS, FragmentSize))
    report_fatal_error("unable to write nop sequence of " +
                       Twine(FragmentSize) + " bytes");
  break;
}

case MCFragment::FT_SymbolId: {
  const MCSymbolIdFragment &SF = cast<MCSymbolIdFragment>(F);
  support::endian::write<uint32_t>(OS, SF.getSymbol()->getIndex(), Endian);
  break;
}

case MCFragment::FT_Org: {
  ++stats::EmittedOrgFragments;
  const MCOrgFragment &OF = cast<MCOrgFragment>(F);

  for (uint64_t i = 0, e = FragmentSize; i != e; ++i)
    OS << char(OF.getValue());

  break;
}

case MCFragment::FT_Dwarf: {
  const MCDwarfLineAddrFragment &OF = cast<MCDwarfLineAddrFragment>(F);
  OS << OF.getContents();
  break;
}
case MCFragment::FT_DwarfFrame: {
  const MCDwarfCallFrameFragment &CF = cast<MCDwarfCallFrameFragment>(F);
  OS << CF.getContents();
  break;
}
case MCFragment::FT_CVInlineLines: {
  const auto &OF = cast<MCCVInlineLineTableFragment>(F);
  OS << OF.getContents();
  break;
}
case MCFragment::FT_CVDefRange: {
  const auto &DRF = cast<MCCVDefRangeFragment>(F);
  OS << DRF.getContents();
  break;
}
case MCFragment::FT_PseudoProbe: {
  const MCPseudoProbeAddrFragment &PF = cast<MCPseudoProbeAddrFragment>(F);
  OS << PF.getContents();
  break;
}
case MCFragment::FT_Dummy:
  llvm_unreachable("Should not have been added")__builtin_unreachable();
}

assert(OS.tell() - Start == FragmentSize &&(static_cast<void> (0))
       "The stream should advance by fragment size")(static_cast<void> (0));
720}

722void MCAssembler::writeSectionData(raw_ostream &OS, const MCSection *Sec,
                                 const MCAsmLayout &Layout) const {
assert(getBackendPtr() && "Expected assembler backend")(static_cast<void> (0));

// Ignore virtual sections.
if (Sec->isVirtualSection()) {
  assert(Layout.getSectionFileSize(Sec) == 0 && "Invalid size for section!")(static_cast<void> (0));

  // Check that contents are only things legal inside a virtual section.
  for (const MCFragment &F : *Sec) {
    switch (F.getKind()) {
    default: llvm_unreachable("Invalid fragment in virtual section!")__builtin_unreachable();
    case MCFragment::FT_Data: {
      // Check that we aren't trying to write a non-zero contents (or fixups)
      // into a virtual section. This is to support clients which use standard
      // directives to fill the contents of virtual sections.
      const MCDataFragment &DF = cast<MCDataFragment>(F);
      if (DF.fixup_begin() != DF.fixup_end())
        getContext().reportError(SMLoc(), Sec->getVirtualSectionKind() +
                                              " section '" + Sec->getName() +
                                              "' cannot have fixups");
      for (unsigned i = 0, e = DF.getContents().size(); i != e; ++i)
        if (DF.getContents()[i]) {
          getContext().reportError(SMLoc(),
                                   Sec->getVirtualSectionKind() +
                                       " section '" + Sec->getName() +
                                       "' cannot have non-zero initializers");
          break;
        }
      break;
    }
    case MCFragment::FT_Align:
      // Check that we aren't trying to write a non-zero value into a virtual
      // section.
      assert((cast<MCAlignFragment>(F).getValueSize() == 0 ||(static_cast<void> (0))
              cast<MCAlignFragment>(F).getValue() == 0) &&(static_cast<void> (0))
             "Invalid align in virtual section!")(static_cast<void> (0));
      break;
    case MCFragment::FT_Fill:
      assert((cast<MCFillFragment>(F).getValue() == 0) &&(static_cast<void> (0))
             "Invalid fill in virtual section!")(static_cast<void> (0));
      break;
    case MCFragment::FT_Org:
      break;
    }
  }

  return;
}

uint64_t Start = OS.tell();
(void)Start;

for (const MCFragment &F : *Sec)
  writeFragment(OS, *this, Layout, F);

assert(getContext().hadError() ||(static_cast<void> (0))
       OS.tell() - Start == Layout.getSectionAddressSize(Sec))(static_cast<void> (0));
780}

782std::tuple<MCValue, uint64_t, bool>
783MCAssembler::handleFixup(const MCAsmLayout &Layout, MCFragment &F,
                       const MCFixup &Fixup) {
// Evaluate the fixup.
MCValue Target;
uint64_t FixedValue;
bool WasForced;
bool IsResolved = evaluateFixup(Layout, Fixup, &F, Target, FixedValue,
                                WasForced);
if (!IsResolved) {
  // The fixup was unresolved, we need a relocation. Inform the object
  // writer of the relocation, and give it an opportunity to adjust the
  // fixup value if need be.
  getWriter().recordRelocation(*this, Layout, &F, Fixup, Target, FixedValue);
}
return std::make_tuple(Target, FixedValue, IsResolved);
798}

800void MCAssembler::layout(MCAsmLayout &Layout) {
assert(getBackendPtr() && "Expected assembler backend")(static_cast<void> (0));
DEBUG_WITH_TYPE("mc-dump", {do { } while (false)
2
←
Loop condition is false.  Exiting loop→
    errs() << "assembler backend - pre-layout\n--\n";do { } while (false)
    dump(); })do { } while (false);

// Create dummy fragments and assign section ordinals.
unsigned SectionIndex = 0;
for (MCSection &Sec : *this) {
  // Create dummy fragments to eliminate any empty sections, this simplifies
  // layout.
  if (Sec.getFragmentList().empty())
    new MCDataFragment(&Sec);

  Sec.setOrdinal(SectionIndex++);
}

// Assign layout order indices to sections and fragments.
for (unsigned i = 0, e = Layout.getSectionOrder().size(); i != e; ++i) {
3
←
Assuming 'i' is not equal to 'e'→
4
←
Loop condition is true.  Entering loop body→
5
←
Assuming 'i' is equal to 'e'→
6
←
Loop condition is false. Execution continues on line 828→
  MCSection *Sec = Layout.getSectionOrder()[i];
  Sec->setLayoutOrder(i);

  unsigned FragmentIndex = 0;
  for (MCFragment &Frag : *Sec)
    Frag.setLayoutOrder(FragmentIndex++);
}

// Layout until everything fits.
while (layoutOnce(Layout)) {
7
←
Loop condition is false. Execution continues on line 838→
  if (getContext().hadError())
    return;
  // Size of fragments in one section can depend on the size of fragments in
  // another. If any fragment has changed size, we have to re-layout (and
  // as a result possibly further relax) all.
  for (MCSection &Sec : *this)
    Layout.invalidateFragmentsFrom(&*Sec.begin());
}

DEBUG_WITH_TYPE("mc-dump", {do { } while (false)
8
←
Loop condition is false.  Exiting loop→
    errs() << "assembler backend - post-relaxation\n--\n";do { } while (false)
    dump(); })do { } while (false);

// Finalize the layout, including fragment lowering.
finishLayout(Layout);
9
←
Calling 'MCAssembler::finishLayout'→

DEBUG_WITH_TYPE("mc-dump", {do { } while (false)
    errs() << "assembler backend - final-layout\n--\n";do { } while (false)
    dump(); })do { } while (false);

// Allow the object writer a chance to perform post-layout binding (for
// example, to set the index fields in the symbol data).
getWriter().executePostLayoutBinding(*this, Layout);

// Evaluate and apply the fixups, generating relocation entries as necessary.
for (MCSection &Sec : *this) {
  for (MCFragment &Frag : Sec) {
    ArrayRef<MCFixup> Fixups;
    MutableArrayRef<char> Contents;
    const MCSubtargetInfo *STI = nullptr;

    // Process MCAlignFragment and MCEncodedFragmentWithFixups here.
    switch (Frag.getKind()) {
    default:
      continue;
    case MCFragment::FT_Align: {
      MCAlignFragment &AF = cast<MCAlignFragment>(Frag);
      // Insert fixup type for code alignment if the target define
      // shouldInsertFixupForCodeAlign target hook.
      if (Sec.UseCodeAlign() && AF.hasEmitNops())
        getBackend().shouldInsertFixupForCodeAlign(*this, Layout, AF);
      continue;
    }
    case MCFragment::FT_Data: {
      MCDataFragment &DF = cast<MCDataFragment>(Frag);
      Fixups = DF.getFixups();
      Contents = DF.getContents();
      STI = DF.getSubtargetInfo();
      assert(!DF.hasInstructions() || STI != nullptr)(static_cast<void> (0));
      break;
    }
    case MCFragment::FT_Relaxable: {
      MCRelaxableFragment &RF = cast<MCRelaxableFragment>(Frag);
      Fixups = RF.getFixups();
      Contents = RF.getContents();
      STI = RF.getSubtargetInfo();
      assert(!RF.hasInstructions() || STI != nullptr)(static_cast<void> (0));
      break;
    }
    case MCFragment::FT_CVDefRange: {
      MCCVDefRangeFragment &CF = cast<MCCVDefRangeFragment>(Frag);
      Fixups = CF.getFixups();
      Contents = CF.getContents();
      break;
    }
    case MCFragment::FT_Dwarf: {
      MCDwarfLineAddrFragment &DF = cast<MCDwarfLineAddrFragment>(Frag);
      Fixups = DF.getFixups();
      Contents = DF.getContents();
      break;
    }
    case MCFragment::FT_DwarfFrame: {
      MCDwarfCallFrameFragment &DF = cast<MCDwarfCallFrameFragment>(Frag);
      Fixups = DF.getFixups();
      Contents = DF.getContents();
      break;
    }
    case MCFragment::FT_PseudoProbe: {
      MCPseudoProbeAddrFragment &PF = cast<MCPseudoProbeAddrFragment>(Frag);
      Fixups = PF.getFixups();
      Contents = PF.getContents();
      break;
    }
    }
    for (const MCFixup &Fixup : Fixups) {
      uint64_t FixedValue;
      bool IsResolved;
      MCValue Target;
      std::tie(Target, FixedValue, IsResolved) =
          handleFixup(Layout, Frag, Fixup);
      getBackend().applyFixup(*this, Fixup, Target, Contents, FixedValue,
                              IsResolved, STI);
    }
  }
}
924}

926void MCAssembler::Finish() {
// Create the layout object.
MCAsmLayout Layout(*this);
layout(Layout);
1
Calling 'MCAssembler::layout'→

// Write the object file.
stats::ObjectBytes += getWriter().writeObject(*this, Layout);
933}

935bool MCAssembler::fixupNeedsRelaxation(const MCFixup &Fixup,
                                     const MCRelaxableFragment *DF,
                                     const MCAsmLayout &Layout) const {
assert(getBackendPtr() && "Expected assembler backend")(static_cast<void> (0));
MCValue Target;
uint64_t Value;
bool WasForced;
bool Resolved = evaluateFixup(Layout, Fixup, DF, Target, Value, WasForced);
if (Target.getSymA() &&
    Target.getSymA()->getKind() == MCSymbolRefExpr::VK_X86_ABS8 &&
    Fixup.getKind() == FK_Data_1)
  return false;
return getBackend().fixupNeedsRelaxationAdvanced(Fixup, Resolved, Value, DF,
                                                 Layout, WasForced);
949}

951bool MCAssembler::fragmentNeedsRelaxation(const MCRelaxableFragment *F,
                                        const MCAsmLayout &Layout) const {
assert(getBackendPtr() && "Expected assembler backend")(static_cast<void> (0));
// If this inst doesn't ever need relaxation, ignore it. This occurs when we
// are intentionally pushing out inst fragments, or because we relaxed a
// previous instruction to one that doesn't need relaxation.
if (!getBackend().mayNeedRelaxation(F->getInst(), *F->getSubtargetInfo()))
  return false;

for (const MCFixup &Fixup : F->getFixups())
  if (fixupNeedsRelaxation(Fixup, F, Layout))
    return true;

return false;
965}

967bool MCAssembler::relaxInstruction(MCAsmLayout &Layout,
                                 MCRelaxableFragment &F) {
assert(getEmitterPtr() &&(static_cast<void> (0))
       "Expected CodeEmitter defined for relaxInstruction")(static_cast<void> (0));
if (!fragmentNeedsRelaxation(&F, Layout))
  return false;

++stats::RelaxedInstructions;

// FIXME-PERF: We could immediately lower out instructions if we can tell
// they are fully resolved, to avoid retesting on later passes.

// Relax the fragment.

MCInst Relaxed = F.getInst();
getBackend().relaxInstruction(Relaxed, *F.getSubtargetInfo());

// Encode the new instruction.
//
// FIXME-PERF: If it matters, we could let the target do this. It can
// probably do so more efficiently in many cases.
SmallVector<MCFixup, 4> Fixups;
SmallString<256> Code;
raw_svector_ostream VecOS(Code);
getEmitter().encodeInstruction(Relaxed, VecOS, Fixups, *F.getSubtargetInfo());

// Update the fragment.
F.setInst(Relaxed);
F.getContents() = Code;
F.getFixups() = Fixups;

return true;
999}

1001bool MCAssembler::relaxLEB(MCAsmLayout &Layout, MCLEBFragment &LF) {
uint64_t OldSize = LF.getContents().size();
int64_t Value;
bool Abs = LF.getValue().evaluateKnownAbsolute(Value, Layout);
if (!Abs)
  report_fatal_error("sleb128 and uleb128 expressions must be absolute");
SmallString<8> &Data = LF.getContents();
Data.clear();
raw_svector_ostream OSE(Data);
// The compiler can generate EH table assembly that is impossible to assemble
// without either adding padding to an LEB fragment or adding extra padding
// to a later alignment fragment. To accommodate such tables, relaxation can
// only increase an LEB fragment size here, not decrease it. See PR35809.
if (LF.isSigned())
  encodeSLEB128(Value, OSE, OldSize);
else
  encodeULEB128(Value, OSE, OldSize);
return OldSize != LF.getContents().size();
1019}

1021/// Check if the branch crosses the boundary.
1022///
1023/// \param StartAddr start address of the fused/unfused branch.
1024/// \param Size size of the fused/unfused branch.
1025/// \param BoundaryAlignment alignment requirement of the branch.
1026/// \returns true if the branch cross the boundary.
1027static bool mayCrossBoundary(uint64_t StartAddr, uint64_t Size,
                           Align BoundaryAlignment) {
uint64_t EndAddr = StartAddr + Size;
return (StartAddr >> Log2(BoundaryAlignment)) !=
       ((EndAddr - 1) >> Log2(BoundaryAlignment));
1032}

1034/// Check if the branch is against the boundary.
1035///
1036/// \param StartAddr start address of the fused/unfused branch.
1037/// \param Size size of the fused/unfused branch.
1038/// \param BoundaryAlignment alignment requirement of the branch.
1039/// \returns true if the branch is against the boundary.
1040static bool isAgainstBoundary(uint64_t StartAddr, uint64_t Size,
                            Align BoundaryAlignment) {
uint64_t EndAddr = StartAddr + Size;
return (EndAddr & (BoundaryAlignment.value() - 1)) == 0;
1044}

1046/// Check if the branch needs padding.
1047///
1048/// \param StartAddr start address of the fused/unfused branch.
1049/// \param Size size of the fused/unfused branch.
1050/// \param BoundaryAlignment alignment requirement of the branch.
1051/// \returns true if the branch needs padding.
1052static bool needPadding(uint64_t StartAddr, uint64_t Size,
                      Align BoundaryAlignment) {
return mayCrossBoundary(StartAddr, Size, BoundaryAlignment) ||
       isAgainstBoundary(StartAddr, Size, BoundaryAlignment);
1056}

1058bool MCAssembler::relaxBoundaryAlign(MCAsmLayout &Layout,
                                   MCBoundaryAlignFragment &BF) {
// BoundaryAlignFragment that doesn't need to align any fragment should not be
// relaxed.
if (!BF.getLastFragment())
  return false;

uint64_t AlignedOffset = Layout.getFragmentOffset(&BF);
uint64_t AlignedSize = 0;
for (const MCFragment *F = BF.getLastFragment(); F != &BF;
     F = F->getPrevNode())
  AlignedSize += computeFragmentSize(Layout, *F);

Align BoundaryAlignment = BF.getAlignment();
uint64_t NewSize = needPadding(AlignedOffset, AlignedSize, BoundaryAlignment)
                       ? offsetToAlignment(AlignedOffset, BoundaryAlignment)
                       : 0U;
if (NewSize == BF.getSize())
  return false;
BF.setSize(NewSize);
Layout.invalidateFragmentsFrom(&BF);
return true;
1080}

1082bool MCAssembler::relaxDwarfLineAddr(MCAsmLayout &Layout,
                                   MCDwarfLineAddrFragment &DF) {

bool WasRelaxed;
if (getBackend().relaxDwarfLineAddr(DF, Layout, WasRelaxed))
  return WasRelaxed;

MCContext &Context = Layout.getAssembler().getContext();
uint64_t OldSize = DF.getContents().size();
int64_t AddrDelta;
bool Abs = DF.getAddrDelta().evaluateKnownAbsolute(AddrDelta, Layout);
assert(Abs && "We created a line delta with an invalid expression")(static_cast<void> (0));
(void)Abs;
int64_t LineDelta;
LineDelta = DF.getLineDelta();
SmallVectorImpl<char> &Data = DF.getContents();
Data.clear();
raw_svector_ostream OSE(Data);
DF.getFixups().clear();

MCDwarfLineAddr::Encode(Context, getDWARFLinetableParams(), LineDelta,
                        AddrDelta, OSE);
return OldSize != Data.size();
1105}

1107bool MCAssembler::relaxDwarfCallFrameFragment(MCAsmLayout &Layout,
                                            MCDwarfCallFrameFragment &DF) {
bool WasRelaxed;
if (getBackend().relaxDwarfCFA(DF, Layout, WasRelaxed))
  return WasRelaxed;

MCContext &Context = Layout.getAssembler().getContext();
uint64_t OldSize = DF.getContents().size();
int64_t AddrDelta;
bool Abs = DF.getAddrDelta().evaluateKnownAbsolute(AddrDelta, Layout);
assert(Abs && "We created call frame with an invalid expression")(static_cast<void> (0));
(void) Abs;
SmallVectorImpl<char> &Data = DF.getContents();
Data.clear();
raw_svector_ostream OSE(Data);
DF.getFixups().clear();

MCDwarfFrameEmitter::EncodeAdvanceLoc(Context, AddrDelta, OSE);
return OldSize != Data.size();
1126}

1128bool MCAssembler::relaxCVInlineLineTable(MCAsmLayout &Layout,
                                       MCCVInlineLineTableFragment &F) {
unsigned OldSize = F.getContents().size();
getContext().getCVContext().encodeInlineLineTable(Layout, F);
return OldSize != F.getContents().size();
1133}

1135bool MCAssembler::relaxCVDefRange(MCAsmLayout &Layout,
                                MCCVDefRangeFragment &F) {
unsigned OldSize = F.getContents().size();
getContext().getCVContext().encodeDefRange(Layout, F);
return OldSize != F.getContents().size();
1140}

1142bool MCAssembler::relaxPseudoProbeAddr(MCAsmLayout &Layout,
                                     MCPseudoProbeAddrFragment &PF) {
uint64_t OldSize = PF.getContents().size();
int64_t AddrDelta;
bool Abs = PF.getAddrDelta().evaluateKnownAbsolute(AddrDelta, Layout);
assert(Abs && "We created a pseudo probe with an invalid expression")(static_cast<void> (0));
(void)Abs;
SmallVectorImpl<char> &Data = PF.getContents();
Data.clear();
raw_svector_ostream OSE(Data);
PF.getFixups().clear();

// AddrDelta is a signed integer
encodeSLEB128(AddrDelta, OSE, OldSize);
return OldSize != Data.size();
1157}

1159bool MCAssembler::relaxFragment(MCAsmLayout &Layout, MCFragment &F) {
switch(F.getKind()) {
default:
  return false;
case MCFragment::FT_Relaxable:
  assert(!getRelaxAll() &&(static_cast<void> (0))
         "Did not expect a MCRelaxableFragment in RelaxAll mode")(static_cast<void> (0));
  return relaxInstruction(Layout, cast<MCRelaxableFragment>(F));
case MCFragment::FT_Dwarf:
  return relaxDwarfLineAddr(Layout, cast<MCDwarfLineAddrFragment>(F));
case MCFragment::FT_DwarfFrame:
  return relaxDwarfCallFrameFragment(Layout,
                                     cast<MCDwarfCallFrameFragment>(F));
case MCFragment::FT_LEB:
  return relaxLEB(Layout, cast<MCLEBFragment>(F));
case MCFragment::FT_BoundaryAlign:
  return relaxBoundaryAlign(Layout, cast<MCBoundaryAlignFragment>(F));
case MCFragment::FT_CVInlineLines:
  return relaxCVInlineLineTable(Layout, cast<MCCVInlineLineTableFragment>(F));
case MCFragment::FT_CVDefRange:
  return relaxCVDefRange(Layout, cast<MCCVDefRangeFragment>(F));
case MCFragment::FT_PseudoProbe:
  return relaxPseudoProbeAddr(Layout, cast<MCPseudoProbeAddrFragment>(F));
}
1183}

1185bool MCAssembler::layoutSectionOnce(MCAsmLayout &Layout, MCSection &Sec) {
// Holds the first fragment which needed relaxing during this layout. It will
// remain NULL if none were relaxed.
// When a fragment is relaxed, all the fragments following it should get
// invalidated because their offset is going to change.
MCFragment *FirstRelaxedFragment = nullptr;

// Attempt to relax all the fragments in the section.
for (MCFragment &Frag : Sec) {
  // Check if this is a fragment that needs relaxation.
  bool RelaxedFrag = relaxFragment(Layout, Frag);
  if (RelaxedFrag && !FirstRelaxedFragment)
    FirstRelaxedFragment = &Frag;
}
if (FirstRelaxedFragment) {
  Layout.invalidateFragmentsFrom(FirstRelaxedFragment);
  return true;
}
return false;
1204}

1206bool MCAssembler::layoutOnce(MCAsmLayout &Layout) {
++stats::RelaxationSteps;

bool WasRelaxed = false;
for (MCSection &Sec : *this) {
  while (layoutSectionOnce(Layout, Sec))
    WasRelaxed = true;
}

return WasRelaxed;
1216}

1218void MCAssembler::finishLayout(MCAsmLayout &Layout) {
assert(getBackendPtr() && "Expected assembler backend")(static_cast<void> (0));
// The layout is done. Mark every fragment as valid.
for (unsigned int i = 0, n = Layout.getSectionOrder().size(); i != n; ++i) {
10
←
Assuming 'i' is not equal to 'n'→
11
←
Loop condition is true.  Entering loop body→
  MCSection &Section = *Layout.getSectionOrder()[i];
  Layout.getFragmentOffset(&*Section.getFragmentList().rbegin());
  computeFragmentSize(Layout, *Section.getFragmentList().rbegin());
12
←
Calling 'MCAssembler::computeFragmentSize'→
}
getBackend().finishLayout(*this, Layout);
1227}

1229#if !defined(NDEBUG1) || defined(LLVM_ENABLE_DUMP)
1230LLVM_DUMP_METHOD__attribute__((noinline)) __attribute__((__used__)) void MCAssembler::dump() const{
raw_ostream &OS = errs();

OS << "<MCAssembler\n";
OS << "  Sections:[\n    ";
for (const_iterator it = begin(), ie = end(); it != ie; ++it) {
  if (it != begin()) OS << ",\n    ";
  it->dump();
}
OS << "],\n";
OS << "  Symbols:[";

for (const_symbol_iterator it = symbol_begin(), ie = symbol_end(); it != ie; ++it) {
  if (it != symbol_begin()) OS << ",\n           ";
  OS << "(";
  it->dump();
  OS << ", Index:" << it->getIndex() << ", ";
  OS << ")";
}
OS << "]>\n";
1250}
1251#endif

←

/build/llvm-toolchain-snapshot-14~++20210903100615+fd66b44ec19e/llvm/include/llvm/Support/Alignment.h

1//===-- llvm/Support/Alignment.h - Useful alignment functions ---*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file contains types to represent alignments.
10// They are instrumented to guarantee some invariants are preserved and prevent
11// invalid manipulations.
12//
13// - Align represents an alignment in bytes, it is always set and always a valid
14// power of two, its minimum value is 1 which means no alignment requirements.
15//
16// - MaybeAlign is an optional type, it may be undefined or set. When it's set
17// you can get the underlying Align type by using the getValue() method.
18//
19//===----------------------------------------------------------------------===//
20 
21#ifndef LLVM_SUPPORT_ALIGNMENT_H_
22#define LLVM_SUPPORT_ALIGNMENT_H_
23 
24#include "llvm/ADT/Optional.h"
25#include "llvm/Support/MathExtras.h"
26#include <cassert>
27#ifndef NDEBUG1
28#include <string>
29#endif // NDEBUG
30 
31namespace llvm {
32 
33#define ALIGN_CHECK_ISPOSITIVE(decl)                                           \
34  assert(decl > 0 && (#decl " should be defined"))(static_cast<void> (0))
35 
36/// This struct is a compact representation of a valid (non-zero power of two)
37/// alignment.
38/// It is suitable for use as static global constants.
39struct Align {
40private:
41  uint8_t ShiftValue = 0; /// The log2 of the required alignment.
42                          /// ShiftValue is less than 64 by construction.
43 
44  friend struct MaybeAlign;
45  friend unsigned Log2(Align);
46  friend bool operator==(Align Lhs, Align Rhs);
47  friend bool operator!=(Align Lhs, Align Rhs);
48  friend bool operator<=(Align Lhs, Align Rhs);
49  friend bool operator>=(Align Lhs, Align Rhs);
50  friend bool operator<(Align Lhs, Align Rhs);
51  friend bool operator>(Align Lhs, Align Rhs);
52  friend unsigned encode(struct MaybeAlign A);
53  friend struct MaybeAlign decodeMaybeAlign(unsigned Value);
54 
55  /// A trivial type to allow construction of constexpr Align.
56  /// This is currently needed to workaround a bug in GCC 5.3 which prevents
57  /// definition of constexpr assign operators.
58  /// https://stackoverflow.com/questions/46756288/explicitly-defaulted-function-cannot-be-declared-as-constexpr-because-the-implic
59  /// FIXME: Remove this, make all assign operators constexpr and introduce user
60  /// defined literals when we don't have to support GCC 5.3 anymore.
61  /// https://llvm.org/docs/GettingStarted.html#getting-a-modern-host-c-toolchain
62  struct LogValue {
63    uint8_t Log;
64  };
65 
66public:
67  /// Default is byte-aligned.
68  constexpr Align() = default;
69  /// Do not perform checks in case of copy/move construct/assign, because the
70  /// checks have been performed when building `Other`.
71  constexpr Align(const Align &Other) = default;
72  constexpr Align(Align &&Other) = default;
73  Align &operator=(const Align &Other) = default;
74  Align &operator=(Align &&Other) = default;
75 
76  explicit Align(uint64_t Value) {
77    assert(Value > 0 && "Value must not be 0")(static_cast<void> (0));
78    assert(llvm::isPowerOf2_64(Value) && "Alignment is not a power of 2")(static_cast<void> (0));
79    ShiftValue = Log2_64(Value);
80    assert(ShiftValue < 64 && "Broken invariant")(static_cast<void> (0));
81  }
82 
83  /// This is a hole in the type system and should not be abused.
84  /// Needed to interact with C for instance.
85  uint64_t value() const { return uint64_t(1) << ShiftValue; }
19
←
The result of the left shift is undefined due to shifting by '255', which is greater or equal to the width of type 'uint64_t'
86 
87  /// Allow constructions of constexpr Align.
88  template <size_t kValue> constexpr static LogValue Constant() {
89    return LogValue{static_cast<uint8_t>(CTLog2<kValue>())};
90  }
91 
92  /// Allow constructions of constexpr Align from types.
93  /// Compile time equivalent to Align(alignof(T)).
94  template <typename T> constexpr static LogValue Of() {
95    return Constant<std::alignment_of<T>::value>();
96  }
97 
98  /// Constexpr constructor from LogValue type.
99  constexpr Align(LogValue CA) : ShiftValue(CA.Log) {}
100};
101 
102/// Treats the value 0 as a 1, so Align is always at least 1.
103inline Align assumeAligned(uint64_t Value) {
104  return Value ? Align(Value) : Align();
105}
106 
107/// This struct is a compact representation of a valid (power of two) or
108/// undefined (0) alignment.
109struct MaybeAlign : public llvm::Optional<Align> {
110private:
111  using UP = llvm::Optional<Align>;
112 
113public:
114  /// Default is undefined.
115  MaybeAlign() = default;
116  /// Do not perform checks in case of copy/move construct/assign, because the
117  /// checks have been performed when building `Other`.
118  MaybeAlign(const MaybeAlign &Other) = default;
119  MaybeAlign &operator=(const MaybeAlign &Other) = default;
120  MaybeAlign(MaybeAlign &&Other) = default;
121  MaybeAlign &operator=(MaybeAlign &&Other) = default;
122 
123  /// Use llvm::Optional<Align> constructor.
124  using UP::UP;
125 
126  explicit MaybeAlign(uint64_t Value) {
127    assert((Value == 0 || llvm::isPowerOf2_64(Value)) &&(static_cast<void> (0))
128           "Alignment is neither 0 nor a power of 2")(static_cast<void> (0));
129    if (Value)
130      emplace(Value);
131  }
132 
133  /// For convenience, returns a valid alignment or 1 if undefined.
134  Align valueOrOne() const { return hasValue() ? getValue() : Align(); }
135};
136 
137/// Checks that SizeInBytes is a multiple of the alignment.
138inline bool isAligned(Align Lhs, uint64_t SizeInBytes) {
139  return SizeInBytes % Lhs.value() == 0;
140}
141 
142/// Checks that Addr is a multiple of the alignment.
143inline bool isAddrAligned(Align Lhs, const void *Addr) {
144  return isAligned(Lhs, reinterpret_cast<uintptr_t>(Addr));
145}
146 
147/// Returns a multiple of A needed to store `Size` bytes.
148inline uint64_t alignTo(uint64_t Size, Align A) {
149  const uint64_t Value = A.value();
18
←
Calling 'Align::value'→
150  // The following line is equivalent to `(Size + Value - 1) / Value * Value`.
151 
152  // The division followed by a multiplication can be thought of as a right
153  // shift followed by a left shift which zeros out the extra bits produced in
154  // the bump; `~(Value - 1)` is a mask where all those bits being zeroed out
155  // are just zero.
156 
157  // Most compilers can generate this code but the pattern may be missed when
158  // multiple functions gets inlined.
159  return (Size + Value - 1) & ~(Value - 1U);
160}
161 
162/// If non-zero \p Skew is specified, the return value will be a minimal integer
163/// that is greater than or equal to \p Size and equal to \p A * N + \p Skew for
164/// some integer N. If \p Skew is larger than \p A, its value is adjusted to '\p
165/// Skew mod \p A'.
166///
167/// Examples:
168/// \code
169///   alignTo(5, Align(8), 7) = 7
170///   alignTo(17, Align(8), 1) = 17
171///   alignTo(~0LL, Align(8), 3) = 3
172/// \endcode
173inline uint64_t alignTo(uint64_t Size, Align A, uint64_t Skew) {
174  const uint64_t Value = A.value();
175  Skew %= Value;
176  return ((Size + Value - 1 - Skew) & ~(Value - 1U)) + Skew;
177}
178 
179/// Returns a multiple of A needed to store `Size` bytes.
180/// Returns `Size` if current alignment is undefined.
181inline uint64_t alignTo(uint64_t Size, MaybeAlign A) {
182  return A ? alignTo(Size, A.getValue()) : Size;
183}
184 
185/// Aligns `Addr` to `Alignment` bytes, rounding up.
186inline uintptr_t alignAddr(const void *Addr, Align Alignment) {
187  uintptr_t ArithAddr = reinterpret_cast<uintptr_t>(Addr);
188  assert(static_cast<uintptr_t>(ArithAddr + Alignment.value() - 1) >=(static_cast<void> (0))
189             ArithAddr &&(static_cast<void> (0))
190         "Overflow")(static_cast<void> (0));
191  return alignTo(ArithAddr, Alignment);
192}
193 
194/// Returns the offset to the next integer (mod 2**64) that is greater than
195/// or equal to \p Value and is a multiple of \p Align.
196inline uint64_t offsetToAlignment(uint64_t Value, Align Alignment) {
197  return alignTo(Value, Alignment) - Value;
16
←
The value 255 is assigned to 'A.ShiftValue'→
17
←
Calling 'alignTo'→
198}
199 
200/// Returns the necessary adjustment for aligning `Addr` to `Alignment`
201/// bytes, rounding up.
202inline uint64_t offsetToAlignedAddr(const void *Addr, Align Alignment) {
203  return offsetToAlignment(reinterpret_cast<uintptr_t>(Addr), Alignment);
204}
205 
206/// Returns the log2 of the alignment.
207inline unsigned Log2(Align A) { return A.ShiftValue; }
208 
209/// Returns the alignment that satisfies both alignments.
210/// Same semantic as MinAlign.
211inline Align commonAlignment(Align A, Align B) { return std::min(A, B); }
212 
213/// Returns the alignment that satisfies both alignments.
214/// Same semantic as MinAlign.
215inline Align commonAlignment(Align A, uint64_t Offset) {
216  return Align(MinAlign(A.value(), Offset));
217}
218 
219/// Returns the alignment that satisfies both alignments.
220/// Same semantic as MinAlign.
221inline MaybeAlign commonAlignment(MaybeAlign A, MaybeAlign B) {
222  return A && B ? commonAlignment(*A, *B) : A ? A : B;
223}
224 
225/// Returns the alignment that satisfies both alignments.
226/// Same semantic as MinAlign.
227inline MaybeAlign commonAlignment(MaybeAlign A, uint64_t Offset) {
228  return MaybeAlign(MinAlign((*A).value(), Offset));
229}
230 
231/// Returns a representation of the alignment that encodes undefined as 0.
232inline unsigned encode(MaybeAlign A) { return A ? A->ShiftValue + 1 : 0; }
233 
234/// Dual operation of the encode function above.
235inline MaybeAlign decodeMaybeAlign(unsigned Value) {
236  if (Value == 0)
237    return MaybeAlign();
238  Align Out;
239  Out.ShiftValue = Value - 1;
240  return Out;
241}
242 
243/// Returns a representation of the alignment, the encoded value is positive by
244/// definition.
245inline unsigned encode(Align A) { return encode(MaybeAlign(A)); }
246 
247/// Comparisons between Align and scalars. Rhs must be positive.
248inline bool operator==(Align Lhs, uint64_t Rhs) {
249  ALIGN_CHECK_ISPOSITIVE(Rhs);
250  return Lhs.value() == Rhs;
251}
252inline bool operator!=(Align Lhs, uint64_t Rhs) {
253  ALIGN_CHECK_ISPOSITIVE(Rhs);
254  return Lhs.value() != Rhs;
255}
256inline bool operator<=(Align Lhs, uint64_t Rhs) {
257  ALIGN_CHECK_ISPOSITIVE(Rhs);
258  return Lhs.value() <= Rhs;
259}
260inline bool operator>=(Align Lhs, uint64_t Rhs) {
261  ALIGN_CHECK_ISPOSITIVE(Rhs);
262  return Lhs.value() >= Rhs;
263}
264inline bool operator<(Align Lhs, uint64_t Rhs) {
265  ALIGN_CHECK_ISPOSITIVE(Rhs);
266  return Lhs.value() < Rhs;
267}
268inline bool operator>(Align Lhs, uint64_t Rhs) {
269  ALIGN_CHECK_ISPOSITIVE(Rhs);
270  return Lhs.value() > Rhs;
271}
272 
273/// Comparisons between MaybeAlign and scalars.
274inline bool operator==(MaybeAlign Lhs, uint64_t Rhs) {
275  return Lhs ? (*Lhs).value() == Rhs : Rhs == 0;
276}
277inline bool operator!=(MaybeAlign Lhs, uint64_t Rhs) {
278  return Lhs ? (*Lhs).value() != Rhs : Rhs != 0;
279}
280 
281/// Comparisons operators between Align.
282inline bool operator==(Align Lhs, Align Rhs) {
283  return Lhs.ShiftValue == Rhs.ShiftValue;
284}
285inline bool operator!=(Align Lhs, Align Rhs) {
286  return Lhs.ShiftValue != Rhs.ShiftValue;
287}
288inline bool operator<=(Align Lhs, Align Rhs) {
289  return Lhs.ShiftValue <= Rhs.ShiftValue;
290}
291inline bool operator>=(Align Lhs, Align Rhs) {
292  return Lhs.ShiftValue >= Rhs.ShiftValue;
293}
294inline bool operator<(Align Lhs, Align Rhs) {
295  return Lhs.ShiftValue < Rhs.ShiftValue;
296}
297inline bool operator>(Align Lhs, Align Rhs) {
298  return Lhs.ShiftValue > Rhs.ShiftValue;
299}
300 
301// Don't allow relational comparisons with MaybeAlign.
302bool operator<=(Align Lhs, MaybeAlign Rhs) = delete;
303bool operator>=(Align Lhs, MaybeAlign Rhs) = delete;
304bool operator<(Align Lhs, MaybeAlign Rhs) = delete;
305bool operator>(Align Lhs, MaybeAlign Rhs) = delete;
306 
307bool operator<=(MaybeAlign Lhs, Align Rhs) = delete;
308bool operator>=(MaybeAlign Lhs, Align Rhs) = delete;
309bool operator<(MaybeAlign Lhs, Align Rhs) = delete;
310bool operator>(MaybeAlign Lhs, Align Rhs) = delete;
311 
312bool operator<=(MaybeAlign Lhs, MaybeAlign Rhs) = delete;
313bool operator>=(MaybeAlign Lhs, MaybeAlign Rhs) = delete;
314bool operator<(MaybeAlign Lhs, MaybeAlign Rhs) = delete;
315bool operator>(MaybeAlign Lhs, MaybeAlign Rhs) = delete;
316 
317inline Align operator*(Align Lhs, uint64_t Rhs) {
318  assert(Rhs > 0 && "Rhs must be positive")(static_cast<void> (0));
319  return Align(Lhs.value() * Rhs);
320}
321 
322inline MaybeAlign operator*(MaybeAlign Lhs, uint64_t Rhs) {
323  assert(Rhs > 0 && "Rhs must be positive")(static_cast<void> (0));
324  return Lhs ? Lhs.getValue() * Rhs : MaybeAlign();
325}
326 
327inline Align operator/(Align Lhs, uint64_t Divisor) {
328  assert(llvm::isPowerOf2_64(Divisor) &&(static_cast<void> (0))
329         "Divisor must be positive and a power of 2")(static_cast<void> (0));
330  assert(Lhs != 1 && "Can't halve byte alignment")(static_cast<void> (0));
331  return Align(Lhs.value() / Divisor);
332}
333 
334inline MaybeAlign operator/(MaybeAlign Lhs, uint64_t Divisor) {
335  assert(llvm::isPowerOf2_64(Divisor) &&(static_cast<void> (0))
336         "Divisor must be positive and a power of 2")(static_cast<void> (0));
337  return Lhs ? Lhs.getValue() / Divisor : MaybeAlign();
338}
339 
340inline Align max(MaybeAlign Lhs, Align Rhs) {
341  return Lhs && *Lhs > Rhs ? *Lhs : Rhs;
342}
343 
344inline Align max(Align Lhs, MaybeAlign Rhs) {
345  return Rhs && *Rhs > Lhs ? *Rhs : Lhs;
346}
347 
348#ifndef NDEBUG1
349// For usage in LLVM_DEBUG macros.
350inline std::string DebugStr(const Align &A) {
351  return std::to_string(A.value());
352}
353// For usage in LLVM_DEBUG macros.
354inline std::string DebugStr(const MaybeAlign &MA) {
355  if (MA)
356    return std::to_string(MA->value());
357  return "None";
358}
359#endif // NDEBUG
360 
361#undef ALIGN_CHECK_ISPOSITIVE
362 
363} // namespace llvm
364 
365#endif // LLVM_SUPPORT_ALIGNMENT_H_