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llvm-mirror/lib/DWARFLinker/DWARFLinker.cpp
Adrian Prantl 49996d074b Add an -object-path-prefix option to dsymutil 
to remap object file paths (but no source paths) before
processing. This is meant to be used for Clang objects where the
module cache location was remapped using ``-fdebug-prefix-map``; to
help dsymutil find the Clang module cache.

<rdar://problem/55685132>

Differential Revision: https://reviews.llvm.org/D76391
2020-03-24 17:13:42 -07:00

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98 KiB
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//=== DWARFLinker.cpp -----------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "llvm/DWARFLinker/DWARFLinker.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/Triple.h"
#include "llvm/CodeGen/NonRelocatableStringpool.h"
#include "llvm/DWARFLinker/DWARFLinkerDeclContext.h"
#include "llvm/DebugInfo/DWARF/DWARFAbbreviationDeclaration.h"
#include "llvm/DebugInfo/DWARF/DWARFContext.h"
#include "llvm/DebugInfo/DWARF/DWARFDataExtractor.h"
#include "llvm/DebugInfo/DWARF/DWARFDebugLine.h"
#include "llvm/DebugInfo/DWARF/DWARFDebugRangeList.h"
#include "llvm/DebugInfo/DWARF/DWARFDie.h"
#include "llvm/DebugInfo/DWARF/DWARFFormValue.h"
#include "llvm/DebugInfo/DWARF/DWARFSection.h"
#include "llvm/DebugInfo/DWARF/DWARFUnit.h"
#include "llvm/Support/DataExtractor.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/ErrorOr.h"
#include "llvm/Support/LEB128.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/ThreadPool.h"
#include <vector>
namespace llvm {
/// Similar to DWARFUnitSection::getUnitForOffset(), but returning our
/// CompileUnit object instead.
static CompileUnit *getUnitForOffset(const UnitListTy &Units, uint64_t Offset) {
auto CU = std::upper_bound(
Units.begin(), Units.end(), Offset,
[](uint64_t LHS, const std::unique_ptr<CompileUnit> &RHS) {
return LHS < RHS->getOrigUnit().getNextUnitOffset();
});
return CU != Units.end() ? CU->get() : nullptr;
}
/// Resolve the DIE attribute reference that has been extracted in \p RefValue.
/// The resulting DIE might be in another CompileUnit which is stored into \p
/// ReferencedCU. \returns null if resolving fails for any reason.
DWARFDie DWARFLinker::resolveDIEReference(const DwarfFile &File,
const UnitListTy &Units,
const DWARFFormValue &RefValue,
const DWARFDie &DIE,
CompileUnit *&RefCU) {
assert(RefValue.isFormClass(DWARFFormValue::FC_Reference));
uint64_t RefOffset = *RefValue.getAsReference();
if ((RefCU = getUnitForOffset(Units, RefOffset)))
if (const auto RefDie = RefCU->getOrigUnit().getDIEForOffset(RefOffset)) {
// In a file with broken references, an attribute might point to a NULL
// DIE.
if (!RefDie.isNULL())
return RefDie;
}
reportWarning("could not find referenced DIE", File, &DIE);
return DWARFDie();
}
/// \returns whether the passed \a Attr type might contain a DIE reference
/// suitable for ODR uniquing.
static bool isODRAttribute(uint16_t Attr) {
switch (Attr) {
default:
return false;
case dwarf::DW_AT_type:
case dwarf::DW_AT_containing_type:
case dwarf::DW_AT_specification:
case dwarf::DW_AT_abstract_origin:
case dwarf::DW_AT_import:
return true;
}
llvm_unreachable("Improper attribute.");
}
static bool isTypeTag(uint16_t Tag) {
switch (Tag) {
case dwarf::DW_TAG_array_type:
case dwarf::DW_TAG_class_type:
case dwarf::DW_TAG_enumeration_type:
case dwarf::DW_TAG_pointer_type:
case dwarf::DW_TAG_reference_type:
case dwarf::DW_TAG_string_type:
case dwarf::DW_TAG_structure_type:
case dwarf::DW_TAG_subroutine_type:
case dwarf::DW_TAG_typedef:
case dwarf::DW_TAG_union_type:
case dwarf::DW_TAG_ptr_to_member_type:
case dwarf::DW_TAG_set_type:
case dwarf::DW_TAG_subrange_type:
case dwarf::DW_TAG_base_type:
case dwarf::DW_TAG_const_type:
case dwarf::DW_TAG_constant:
case dwarf::DW_TAG_file_type:
case dwarf::DW_TAG_namelist:
case dwarf::DW_TAG_packed_type:
case dwarf::DW_TAG_volatile_type:
case dwarf::DW_TAG_restrict_type:
case dwarf::DW_TAG_atomic_type:
case dwarf::DW_TAG_interface_type:
case dwarf::DW_TAG_unspecified_type:
case dwarf::DW_TAG_shared_type:
return true;
default:
break;
}
return false;
}
AddressesMap::~AddressesMap() {}
DwarfEmitter::~DwarfEmitter() {}
static Optional<StringRef> StripTemplateParameters(StringRef Name) {
// We are looking for template parameters to strip from Name. e.g.
//
// operator<<B>
//
// We look for > at the end but if it does not contain any < then we
// have something like operator>>. We check for the operator<=> case.
if (!Name.endswith(">") || Name.count("<") == 0 || Name.endswith("<=>"))
return {};
// How many < until we have the start of the template parameters.
size_t NumLeftAnglesToSkip = 1;
// If we have operator<=> then we need to skip its < as well.
NumLeftAnglesToSkip += Name.count("<=>");
size_t RightAngleCount = Name.count('>');
size_t LeftAngleCount = Name.count('<');
// If we have more < than > we have operator< or operator<<
// we to account for their < as well.
if (LeftAngleCount > RightAngleCount)
NumLeftAnglesToSkip += LeftAngleCount - RightAngleCount;
size_t StartOfTemplate = 0;
while (NumLeftAnglesToSkip--)
StartOfTemplate = Name.find('<', StartOfTemplate) + 1;
return Name.substr(0, StartOfTemplate - 1);
}
bool DWARFLinker::DIECloner::getDIENames(const DWARFDie &Die,
AttributesInfo &Info,
OffsetsStringPool &StringPool,
bool StripTemplate) {
// This function will be called on DIEs having low_pcs and
// ranges. As getting the name might be more expansive, filter out
// blocks directly.
if (Die.getTag() == dwarf::DW_TAG_lexical_block)
return false;
// FIXME: a bit wasteful as the first getName might return the
// short name.
if (!Info.MangledName)
if (const char *MangledName = Die.getName(DINameKind::LinkageName))
Info.MangledName = StringPool.getEntry(MangledName);
if (!Info.Name)
if (const char *Name = Die.getName(DINameKind::ShortName))
Info.Name = StringPool.getEntry(Name);
if (StripTemplate && Info.Name && Info.MangledName != Info.Name) {
StringRef Name = Info.Name.getString();
if (Optional<StringRef> StrippedName = StripTemplateParameters(Name))
Info.NameWithoutTemplate = StringPool.getEntry(*StrippedName);
}
return Info.Name || Info.MangledName;
}
/// Resolve the relative path to a build artifact referenced by DWARF by
/// applying DW_AT_comp_dir.
static void resolveRelativeObjectPath(SmallVectorImpl<char> &Buf, DWARFDie CU) {
sys::path::append(Buf, dwarf::toString(CU.find(dwarf::DW_AT_comp_dir), ""));
}
/// Collect references to parseable Swift interfaces in imported
/// DW_TAG_module blocks.
static void analyzeImportedModule(
const DWARFDie &DIE, CompileUnit &CU,
swiftInterfacesMap *ParseableSwiftInterfaces,
std::function<void(const Twine &, const DWARFDie &)> ReportWarning) {
if (CU.getLanguage() != dwarf::DW_LANG_Swift)
return;
if (!ParseableSwiftInterfaces)
return;
StringRef Path = dwarf::toStringRef(DIE.find(dwarf::DW_AT_LLVM_include_path));
if (!Path.endswith(".swiftinterface"))
return;
// Don't track interfaces that are part of the SDK.
StringRef SysRoot = dwarf::toStringRef(DIE.find(dwarf::DW_AT_LLVM_sysroot));
if (SysRoot.empty())
SysRoot = CU.getSysRoot();
if (!SysRoot.empty() && Path.startswith(SysRoot))
return;
if (Optional<DWARFFormValue> Val = DIE.find(dwarf::DW_AT_name))
if (Optional<const char *> Name = Val->getAsCString()) {
auto &Entry = (*ParseableSwiftInterfaces)[*Name];
// The prepend path is applied later when copying.
DWARFDie CUDie = CU.getOrigUnit().getUnitDIE();
SmallString<128> ResolvedPath;
if (sys::path::is_relative(Path))
resolveRelativeObjectPath(ResolvedPath, CUDie);
sys::path::append(ResolvedPath, Path);
if (!Entry.empty() && Entry != ResolvedPath)
ReportWarning(
Twine("Conflicting parseable interfaces for Swift Module ") +
*Name + ": " + Entry + " and " + Path,
DIE);
Entry = std::string(ResolvedPath.str());
}
}
/// Recursive helper to build the global DeclContext information and
/// gather the child->parent relationships in the original compile unit.
///
/// \return true when this DIE and all of its children are only
/// forward declarations to types defined in external clang modules
/// (i.e., forward declarations that are children of a DW_TAG_module).
static bool analyzeContextInfo(
const DWARFDie &DIE, unsigned ParentIdx, CompileUnit &CU,
DeclContext *CurrentDeclContext, UniquingStringPool &StringPool,
DeclContextTree &Contexts, uint64_t ModulesEndOffset,
swiftInterfacesMap *ParseableSwiftInterfaces,
std::function<void(const Twine &, const DWARFDie &)> ReportWarning,
bool InImportedModule = false) {
unsigned MyIdx = CU.getOrigUnit().getDIEIndex(DIE);
CompileUnit::DIEInfo &Info = CU.getInfo(MyIdx);
// Clang imposes an ODR on modules(!) regardless of the language:
// "The module-id should consist of only a single identifier,
// which provides the name of the module being defined. Each
// module shall have a single definition."
//
// This does not extend to the types inside the modules:
// "[I]n C, this implies that if two structs are defined in
// different submodules with the same name, those two types are
// distinct types (but may be compatible types if their
// definitions match)."
//
// We treat non-C++ modules like namespaces for this reason.
if (DIE.getTag() == dwarf::DW_TAG_module && ParentIdx == 0 &&
dwarf::toString(DIE.find(dwarf::DW_AT_name), "") !=
CU.getClangModuleName()) {
InImportedModule = true;
analyzeImportedModule(DIE, CU, ParseableSwiftInterfaces, ReportWarning);
}
Info.ParentIdx = ParentIdx;
bool InClangModule = CU.isClangModule() || InImportedModule;
if (CU.hasODR() || InClangModule) {
if (CurrentDeclContext) {
auto PtrInvalidPair = Contexts.getChildDeclContext(
*CurrentDeclContext, DIE, CU, StringPool, InClangModule);
CurrentDeclContext = PtrInvalidPair.getPointer();
Info.Ctxt =
PtrInvalidPair.getInt() ? nullptr : PtrInvalidPair.getPointer();
if (Info.Ctxt)
Info.Ctxt->setDefinedInClangModule(InClangModule);
} else
Info.Ctxt = CurrentDeclContext = nullptr;
}
Info.Prune = InImportedModule;
if (DIE.hasChildren())
for (auto Child : DIE.children())
Info.Prune &= analyzeContextInfo(Child, MyIdx, CU, CurrentDeclContext,
StringPool, Contexts, ModulesEndOffset,
ParseableSwiftInterfaces, ReportWarning,
InImportedModule);
// Prune this DIE if it is either a forward declaration inside a
// DW_TAG_module or a DW_TAG_module that contains nothing but
// forward declarations.
Info.Prune &= (DIE.getTag() == dwarf::DW_TAG_module) ||
(isTypeTag(DIE.getTag()) &&
dwarf::toUnsigned(DIE.find(dwarf::DW_AT_declaration), 0));
// Only prune forward declarations inside a DW_TAG_module for which a
// definition exists elsewhere.
if (ModulesEndOffset == 0)
Info.Prune &= Info.Ctxt && Info.Ctxt->getCanonicalDIEOffset();
else
Info.Prune &= Info.Ctxt && Info.Ctxt->getCanonicalDIEOffset() > 0 &&
Info.Ctxt->getCanonicalDIEOffset() <= ModulesEndOffset;
return Info.Prune;
}
static bool dieNeedsChildrenToBeMeaningful(uint32_t Tag) {
switch (Tag) {
default:
return false;
case dwarf::DW_TAG_class_type:
case dwarf::DW_TAG_common_block:
case dwarf::DW_TAG_lexical_block:
case dwarf::DW_TAG_structure_type:
case dwarf::DW_TAG_subprogram:
case dwarf::DW_TAG_subroutine_type:
case dwarf::DW_TAG_union_type:
return true;
}
llvm_unreachable("Invalid Tag");
}
void DWARFLinker::cleanupAuxiliarryData(LinkContext &Context) {
Context.clear();
for (auto I = DIEBlocks.begin(), E = DIEBlocks.end(); I != E; ++I)
(*I)->~DIEBlock();
for (auto I = DIELocs.begin(), E = DIELocs.end(); I != E; ++I)
(*I)->~DIELoc();
DIEBlocks.clear();
DIELocs.clear();
DIEAlloc.Reset();
}
/// Get the starting and ending (exclusive) offset for the
/// attribute with index \p Idx descibed by \p Abbrev. \p Offset is
/// supposed to point to the position of the first attribute described
/// by \p Abbrev.
/// \return [StartOffset, EndOffset) as a pair.
static std::pair<uint64_t, uint64_t>
getAttributeOffsets(const DWARFAbbreviationDeclaration *Abbrev, unsigned Idx,
uint64_t Offset, const DWARFUnit &Unit) {
DataExtractor Data = Unit.getDebugInfoExtractor();
for (unsigned I = 0; I < Idx; ++I)
DWARFFormValue::skipValue(Abbrev->getFormByIndex(I), Data, &Offset,
Unit.getFormParams());
uint64_t End = Offset;
DWARFFormValue::skipValue(Abbrev->getFormByIndex(Idx), Data, &End,
Unit.getFormParams());
return std::make_pair(Offset, End);
}
/// Check if a variable describing DIE should be kept.
/// \returns updated TraversalFlags.
unsigned DWARFLinker::shouldKeepVariableDIE(AddressesMap &RelocMgr,
const DWARFDie &DIE,
CompileUnit &Unit,
CompileUnit::DIEInfo &MyInfo,
unsigned Flags) {
const auto *Abbrev = DIE.getAbbreviationDeclarationPtr();
// Global variables with constant value can always be kept.
if (!(Flags & TF_InFunctionScope) &&
Abbrev->findAttributeIndex(dwarf::DW_AT_const_value)) {
MyInfo.InDebugMap = true;
return Flags | TF_Keep;
}
Optional<uint32_t> LocationIdx =
Abbrev->findAttributeIndex(dwarf::DW_AT_location);
if (!LocationIdx)
return Flags;
uint64_t Offset = DIE.getOffset() + getULEB128Size(Abbrev->getCode());
const DWARFUnit &OrigUnit = Unit.getOrigUnit();
uint64_t LocationOffset, LocationEndOffset;
std::tie(LocationOffset, LocationEndOffset) =
getAttributeOffsets(Abbrev, *LocationIdx, Offset, OrigUnit);
// See if there is a relocation to a valid debug map entry inside
// this variable's location. The order is important here. We want to
// always check if the variable has a valid relocation, so that the
// DIEInfo is filled. However, we don't want a static variable in a
// function to force us to keep the enclosing function.
if (!RelocMgr.hasValidRelocationAt(LocationOffset, LocationEndOffset,
MyInfo) ||
(Flags & TF_InFunctionScope))
return Flags;
if (Options.Verbose) {
outs() << "Keeping variable DIE:";
DIDumpOptions DumpOpts;
DumpOpts.ChildRecurseDepth = 0;
DumpOpts.Verbose = Options.Verbose;
DIE.dump(outs(), 8 /* Indent */, DumpOpts);
}
return Flags | TF_Keep;
}
/// Check if a function describing DIE should be kept.
/// \returns updated TraversalFlags.
unsigned DWARFLinker::shouldKeepSubprogramDIE(
AddressesMap &RelocMgr, RangesTy &Ranges, const DWARFDie &DIE,
const DwarfFile &File, CompileUnit &Unit, CompileUnit::DIEInfo &MyInfo,
unsigned Flags) {
const auto *Abbrev = DIE.getAbbreviationDeclarationPtr();
Flags |= TF_InFunctionScope;
Optional<uint32_t> LowPcIdx = Abbrev->findAttributeIndex(dwarf::DW_AT_low_pc);
if (!LowPcIdx)
return Flags;
uint64_t Offset = DIE.getOffset() + getULEB128Size(Abbrev->getCode());
DWARFUnit &OrigUnit = Unit.getOrigUnit();
uint64_t LowPcOffset, LowPcEndOffset;
std::tie(LowPcOffset, LowPcEndOffset) =
getAttributeOffsets(Abbrev, *LowPcIdx, Offset, OrigUnit);
auto LowPc = dwarf::toAddress(DIE.find(dwarf::DW_AT_low_pc));
assert(LowPc.hasValue() && "low_pc attribute is not an address.");
if (!LowPc ||
!RelocMgr.hasValidRelocationAt(LowPcOffset, LowPcEndOffset, MyInfo))
return Flags;
if (Options.Verbose) {
outs() << "Keeping subprogram DIE:";
DIDumpOptions DumpOpts;
DumpOpts.ChildRecurseDepth = 0;
DumpOpts.Verbose = Options.Verbose;
DIE.dump(outs(), 8 /* Indent */, DumpOpts);
}
if (DIE.getTag() == dwarf::DW_TAG_label) {
if (Unit.hasLabelAt(*LowPc))
return Flags;
// FIXME: dsymutil-classic compat. dsymutil-classic doesn't consider labels
// that don't fall into the CU's aranges. This is wrong IMO. Debug info
// generation bugs aside, this is really wrong in the case of labels, where
// a label marking the end of a function will have a PC == CU's high_pc.
if (dwarf::toAddress(OrigUnit.getUnitDIE().find(dwarf::DW_AT_high_pc))
.getValueOr(UINT64_MAX) <= LowPc)
return Flags;
Unit.addLabelLowPc(*LowPc, MyInfo.AddrAdjust);
return Flags | TF_Keep;
}
Flags |= TF_Keep;
Optional<uint64_t> HighPc = DIE.getHighPC(*LowPc);
if (!HighPc) {
reportWarning("Function without high_pc. Range will be discarded.\n", File,
&DIE);
return Flags;
}
// Replace the debug map range with a more accurate one.
Ranges[*LowPc] = ObjFileAddressRange(*HighPc, MyInfo.AddrAdjust);
Unit.addFunctionRange(*LowPc, *HighPc, MyInfo.AddrAdjust);
return Flags;
}
/// Check if a DIE should be kept.
/// \returns updated TraversalFlags.
unsigned DWARFLinker::shouldKeepDIE(AddressesMap &RelocMgr, RangesTy &Ranges,
const DWARFDie &DIE, const DwarfFile &File,
CompileUnit &Unit,
CompileUnit::DIEInfo &MyInfo,
unsigned Flags) {
switch (DIE.getTag()) {
case dwarf::DW_TAG_constant:
case dwarf::DW_TAG_variable:
return shouldKeepVariableDIE(RelocMgr, DIE, Unit, MyInfo, Flags);
case dwarf::DW_TAG_subprogram:
case dwarf::DW_TAG_label:
return shouldKeepSubprogramDIE(RelocMgr, Ranges, DIE, File, Unit, MyInfo,
Flags);
case dwarf::DW_TAG_base_type:
// DWARF Expressions may reference basic types, but scanning them
// is expensive. Basic types are tiny, so just keep all of them.
case dwarf::DW_TAG_imported_module:
case dwarf::DW_TAG_imported_declaration:
case dwarf::DW_TAG_imported_unit:
// We always want to keep these.
return Flags | TF_Keep;
default:
break;
}
return Flags;
}
/// Helper that updates the completeness of the current DIE based on the
/// completeness of one of its children. It depends on the incompleteness of
/// the children already being computed.
static void updateChildIncompleteness(const DWARFDie &Die, CompileUnit &CU,
CompileUnit::DIEInfo &ChildInfo) {
switch (Die.getTag()) {
case dwarf::DW_TAG_structure_type:
case dwarf::DW_TAG_class_type:
break;
default:
return;
}
unsigned Idx = CU.getOrigUnit().getDIEIndex(Die);
CompileUnit::DIEInfo &MyInfo = CU.getInfo(Idx);
if (ChildInfo.Incomplete || ChildInfo.Prune)
MyInfo.Incomplete = true;
}
/// Helper that updates the completeness of the current DIE based on the
/// completeness of the DIEs it references. It depends on the incompleteness of
/// the referenced DIE already being computed.
static void updateRefIncompleteness(const DWARFDie &Die, CompileUnit &CU,
CompileUnit::DIEInfo &RefInfo) {
switch (Die.getTag()) {
case dwarf::DW_TAG_typedef:
case dwarf::DW_TAG_member:
case dwarf::DW_TAG_reference_type:
case dwarf::DW_TAG_ptr_to_member_type:
case dwarf::DW_TAG_pointer_type:
break;
default:
return;
}
unsigned Idx = CU.getOrigUnit().getDIEIndex(Die);
CompileUnit::DIEInfo &MyInfo = CU.getInfo(Idx);
if (MyInfo.Incomplete)
return;
if (RefInfo.Incomplete)
MyInfo.Incomplete = true;
}
/// Look at the children of the given DIE and decide whether they should be
/// kept.
void DWARFLinker::lookForChildDIEsToKeep(
const DWARFDie &Die, CompileUnit &CU, unsigned Flags,
SmallVectorImpl<WorklistItem> &Worklist) {
// The TF_ParentWalk flag tells us that we are currently walking up the
// parent chain of a required DIE, and we don't want to mark all the children
// of the parents as kept (consider for example a DW_TAG_namespace node in
// the parent chain). There are however a set of DIE types for which we want
// to ignore that directive and still walk their children.
if (dieNeedsChildrenToBeMeaningful(Die.getTag()))
Flags &= ~DWARFLinker::TF_ParentWalk;
// We're finished if this DIE has no children or we're walking the parent
// chain.
if (!Die.hasChildren() || (Flags & DWARFLinker::TF_ParentWalk))
return;
// Add children in reverse order to the worklist to effectively process them
// in order.
for (auto Child : reverse(Die.children())) {
// Add a worklist item before every child to calculate incompleteness right
// after the current child is processed.
unsigned Idx = CU.getOrigUnit().getDIEIndex(Child);
CompileUnit::DIEInfo &ChildInfo = CU.getInfo(Idx);
Worklist.emplace_back(Die, CU, WorklistItemType::UpdateChildIncompleteness,
&ChildInfo);
Worklist.emplace_back(Child, CU, Flags);
}
}
/// Look at DIEs referenced by the given DIE and decide whether they should be
/// kept. All DIEs referenced though attributes should be kept.
void DWARFLinker::lookForRefDIEsToKeep(
const DWARFDie &Die, CompileUnit &CU, unsigned Flags,
const UnitListTy &Units, const DwarfFile &File,
SmallVectorImpl<WorklistItem> &Worklist) {
bool UseOdr = (Flags & DWARFLinker::TF_DependencyWalk)
? (Flags & DWARFLinker::TF_ODR)
: CU.hasODR();
DWARFUnit &Unit = CU.getOrigUnit();
DWARFDataExtractor Data = Unit.getDebugInfoExtractor();
const auto *Abbrev = Die.getAbbreviationDeclarationPtr();
uint64_t Offset = Die.getOffset() + getULEB128Size(Abbrev->getCode());
SmallVector<std::pair<DWARFDie, CompileUnit &>, 4> ReferencedDIEs;
for (const auto &AttrSpec : Abbrev->attributes()) {
DWARFFormValue Val(AttrSpec.Form);
if (!Val.isFormClass(DWARFFormValue::FC_Reference) ||
AttrSpec.Attr == dwarf::DW_AT_sibling) {
DWARFFormValue::skipValue(AttrSpec.Form, Data, &Offset,
Unit.getFormParams());
continue;
}
Val.extractValue(Data, &Offset, Unit.getFormParams(), &Unit);
CompileUnit *ReferencedCU;
if (auto RefDie =
resolveDIEReference(File, Units, Val, Die, ReferencedCU)) {
uint32_t RefIdx = ReferencedCU->getOrigUnit().getDIEIndex(RefDie);
CompileUnit::DIEInfo &Info = ReferencedCU->getInfo(RefIdx);
bool IsModuleRef = Info.Ctxt && Info.Ctxt->getCanonicalDIEOffset() &&
Info.Ctxt->isDefinedInClangModule();
// If the referenced DIE has a DeclContext that has already been
// emitted, then do not keep the one in this CU. We'll link to
// the canonical DIE in cloneDieReferenceAttribute.
//
// FIXME: compatibility with dsymutil-classic. UseODR shouldn't
// be necessary and could be advantageously replaced by
// ReferencedCU->hasODR() && CU.hasODR().
//
// FIXME: compatibility with dsymutil-classic. There is no
// reason not to unique ref_addr references.
if (AttrSpec.Form != dwarf::DW_FORM_ref_addr && (UseOdr || IsModuleRef) &&
Info.Ctxt &&
Info.Ctxt != ReferencedCU->getInfo(Info.ParentIdx).Ctxt &&
Info.Ctxt->getCanonicalDIEOffset() && isODRAttribute(AttrSpec.Attr))
continue;
// Keep a module forward declaration if there is no definition.
if (!(isODRAttribute(AttrSpec.Attr) && Info.Ctxt &&
Info.Ctxt->getCanonicalDIEOffset()))
Info.Prune = false;
ReferencedDIEs.emplace_back(RefDie, *ReferencedCU);
}
}
unsigned ODRFlag = UseOdr ? DWARFLinker::TF_ODR : 0;
// Add referenced DIEs in reverse order to the worklist to effectively
// process them in order.
for (auto &P : reverse(ReferencedDIEs)) {
// Add a worklist item before every child to calculate incompleteness right
// after the current child is processed.
uint32_t RefIdx = P.second.getOrigUnit().getDIEIndex(P.first);
CompileUnit::DIEInfo &Info = P.second.getInfo(RefIdx);
Worklist.emplace_back(Die, CU, WorklistItemType::UpdateRefIncompleteness,
&Info);
Worklist.emplace_back(P.first, P.second,
DWARFLinker::TF_Keep |
DWARFLinker::TF_DependencyWalk | ODRFlag);
}
}
/// Look at the parent of the given DIE and decide whether they should be kept.
void DWARFLinker::lookForParentDIEsToKeep(
unsigned AncestorIdx, CompileUnit &CU, unsigned Flags,
SmallVectorImpl<WorklistItem> &Worklist) {
// Stop if we encounter an ancestor that's already marked as kept.
if (CU.getInfo(AncestorIdx).Keep)
return;
DWARFUnit &Unit = CU.getOrigUnit();
DWARFDie ParentDIE = Unit.getDIEAtIndex(AncestorIdx);
Worklist.emplace_back(CU.getInfo(AncestorIdx).ParentIdx, CU, Flags);
Worklist.emplace_back(ParentDIE, CU, Flags);
}
/// Recursively walk the \p DIE tree and look for DIEs to keep. Store that
/// information in \p CU's DIEInfo.
///
/// This function is the entry point of the DIE selection algorithm. It is
/// expected to walk the DIE tree in file order and (though the mediation of
/// its helper) call hasValidRelocation() on each DIE that might be a 'root
/// DIE' (See DwarfLinker class comment).
///
/// While walking the dependencies of root DIEs, this function is also called,
/// but during these dependency walks the file order is not respected. The
/// TF_DependencyWalk flag tells us which kind of traversal we are currently
/// doing.
///
/// The recursive algorithm is implemented iteratively as a work list because
/// very deep recursion could exhaust the stack for large projects. The work
/// list acts as a scheduler for different types of work that need to be
/// performed.
///
/// The recursive nature of the algorithm is simulated by running the "main"
/// algorithm (LookForDIEsToKeep) followed by either looking at more DIEs
/// (LookForChildDIEsToKeep, LookForRefDIEsToKeep, LookForParentDIEsToKeep) or
/// fixing up a computed property (UpdateChildIncompleteness,
/// UpdateRefIncompleteness).
///
/// The return value indicates whether the DIE is incomplete.
void DWARFLinker::lookForDIEsToKeep(AddressesMap &AddressesMap,
RangesTy &Ranges, const UnitListTy &Units,
const DWARFDie &Die, const DwarfFile &File,
CompileUnit &Cu, unsigned Flags) {
// LIFO work list.
SmallVector<WorklistItem, 4> Worklist;
Worklist.emplace_back(Die, Cu, Flags);
while (!Worklist.empty()) {
WorklistItem Current = Worklist.back();
Worklist.pop_back();
// Look at the worklist type to decide what kind of work to perform.
switch (Current.Type) {
case WorklistItemType::UpdateChildIncompleteness:
updateChildIncompleteness(Current.Die, Current.CU, *Current.OtherInfo);
continue;
case WorklistItemType::UpdateRefIncompleteness:
updateRefIncompleteness(Current.Die, Current.CU, *Current.OtherInfo);
continue;
case WorklistItemType::LookForChildDIEsToKeep:
lookForChildDIEsToKeep(Current.Die, Current.CU, Current.Flags, Worklist);
continue;
case WorklistItemType::LookForRefDIEsToKeep:
lookForRefDIEsToKeep(Current.Die, Current.CU, Current.Flags, Units, File,
Worklist);
continue;
case WorklistItemType::LookForParentDIEsToKeep:
lookForParentDIEsToKeep(Current.AncestorIdx, Current.CU, Current.Flags,
Worklist);
continue;
case WorklistItemType::LookForDIEsToKeep:
break;
}
unsigned Idx = Current.CU.getOrigUnit().getDIEIndex(Current.Die);
CompileUnit::DIEInfo &MyInfo = Current.CU.getInfo(Idx);
if (MyInfo.Prune)
continue;
// If the Keep flag is set, we are marking a required DIE's dependencies.
// If our target is already marked as kept, we're all set.
bool AlreadyKept = MyInfo.Keep;
if ((Current.Flags & TF_DependencyWalk) && AlreadyKept)
continue;
// We must not call shouldKeepDIE while called from keepDIEAndDependencies,
// because it would screw up the relocation finding logic.
if (!(Current.Flags & TF_DependencyWalk))
Current.Flags = shouldKeepDIE(AddressesMap, Ranges, Current.Die, File,
Current.CU, MyInfo, Current.Flags);
// Finish by looking for child DIEs. Because of the LIFO worklist we need
// to schedule that work before any subsequent items are added to the
// worklist.
Worklist.emplace_back(Current.Die, Current.CU, Current.Flags,
WorklistItemType::LookForChildDIEsToKeep);
if (AlreadyKept || !(Current.Flags & TF_Keep))
continue;
// If it is a newly kept DIE mark it as well as all its dependencies as
// kept.
MyInfo.Keep = true;
// We're looking for incomplete types.
MyInfo.Incomplete =
Current.Die.getTag() != dwarf::DW_TAG_subprogram &&
Current.Die.getTag() != dwarf::DW_TAG_member &&
dwarf::toUnsigned(Current.Die.find(dwarf::DW_AT_declaration), 0);
// After looking at the parent chain, look for referenced DIEs. Because of
// the LIFO worklist we need to schedule that work before any subsequent
// items are added to the worklist.
Worklist.emplace_back(Current.Die, Current.CU, Current.Flags,
WorklistItemType::LookForRefDIEsToKeep);
bool UseOdr = (Current.Flags & TF_DependencyWalk) ? (Current.Flags & TF_ODR)
: Current.CU.hasODR();
unsigned ODRFlag = UseOdr ? TF_ODR : 0;
unsigned ParFlags = TF_ParentWalk | TF_Keep | TF_DependencyWalk | ODRFlag;
// Now schedule the parent walk.
Worklist.emplace_back(MyInfo.ParentIdx, Current.CU, ParFlags);
}
}
/// Assign an abbreviation number to \p Abbrev.
///
/// Our DIEs get freed after every DebugMapObject has been processed,
/// thus the FoldingSet we use to unique DIEAbbrevs cannot refer to
/// the instances hold by the DIEs. When we encounter an abbreviation
/// that we don't know, we create a permanent copy of it.
void DWARFLinker::assignAbbrev(DIEAbbrev &Abbrev) {
// Check the set for priors.
FoldingSetNodeID ID;
Abbrev.Profile(ID);
void *InsertToken;
DIEAbbrev *InSet = AbbreviationsSet.FindNodeOrInsertPos(ID, InsertToken);
// If it's newly added.
if (InSet) {
// Assign existing abbreviation number.
Abbrev.setNumber(InSet->getNumber());
} else {
// Add to abbreviation list.
Abbreviations.push_back(
std::make_unique<DIEAbbrev>(Abbrev.getTag(), Abbrev.hasChildren()));
for (const auto &Attr : Abbrev.getData())
Abbreviations.back()->AddAttribute(Attr.getAttribute(), Attr.getForm());
AbbreviationsSet.InsertNode(Abbreviations.back().get(), InsertToken);
// Assign the unique abbreviation number.
Abbrev.setNumber(Abbreviations.size());
Abbreviations.back()->setNumber(Abbreviations.size());
}
}
unsigned DWARFLinker::DIECloner::cloneStringAttribute(
DIE &Die, AttributeSpec AttrSpec, const DWARFFormValue &Val,
const DWARFUnit &U, OffsetsStringPool &StringPool, AttributesInfo &Info) {
// Switch everything to out of line strings.
const char *String = *Val.getAsCString();
auto StringEntry = StringPool.getEntry(String);
// Update attributes info.
if (AttrSpec.Attr == dwarf::DW_AT_name)
Info.Name = StringEntry;
else if (AttrSpec.Attr == dwarf::DW_AT_MIPS_linkage_name ||
AttrSpec.Attr == dwarf::DW_AT_linkage_name)
Info.MangledName = StringEntry;
Die.addValue(DIEAlloc, dwarf::Attribute(AttrSpec.Attr), dwarf::DW_FORM_strp,
DIEInteger(StringEntry.getOffset()));
return 4;
}
unsigned DWARFLinker::DIECloner::cloneDieReferenceAttribute(
DIE &Die, const DWARFDie &InputDIE, AttributeSpec AttrSpec,
unsigned AttrSize, const DWARFFormValue &Val, const DwarfFile &File,
CompileUnit &Unit) {
const DWARFUnit &U = Unit.getOrigUnit();
uint64_t Ref = *Val.getAsReference();
DIE *NewRefDie = nullptr;
CompileUnit *RefUnit = nullptr;
DeclContext *Ctxt = nullptr;
DWARFDie RefDie =
Linker.resolveDIEReference(File, CompileUnits, Val, InputDIE, RefUnit);
// If the referenced DIE is not found, drop the attribute.
if (!RefDie || AttrSpec.Attr == dwarf::DW_AT_sibling)
return 0;
unsigned Idx = RefUnit->getOrigUnit().getDIEIndex(RefDie);
CompileUnit::DIEInfo &RefInfo = RefUnit->getInfo(Idx);
// If we already have emitted an equivalent DeclContext, just point
// at it.
if (isODRAttribute(AttrSpec.Attr)) {
Ctxt = RefInfo.Ctxt;
if (Ctxt && Ctxt->getCanonicalDIEOffset()) {
DIEInteger Attr(Ctxt->getCanonicalDIEOffset());
Die.addValue(DIEAlloc, dwarf::Attribute(AttrSpec.Attr),
dwarf::DW_FORM_ref_addr, Attr);
return U.getRefAddrByteSize();
}
}
if (!RefInfo.Clone) {
assert(Ref > InputDIE.getOffset());
// We haven't cloned this DIE yet. Just create an empty one and
// store it. It'll get really cloned when we process it.
RefInfo.Clone = DIE::get(DIEAlloc, dwarf::Tag(RefDie.getTag()));
}
NewRefDie = RefInfo.Clone;
if (AttrSpec.Form == dwarf::DW_FORM_ref_addr ||
(Unit.hasODR() && isODRAttribute(AttrSpec.Attr))) {
// We cannot currently rely on a DIEEntry to emit ref_addr
// references, because the implementation calls back to DwarfDebug
// to find the unit offset. (We don't have a DwarfDebug)
// FIXME: we should be able to design DIEEntry reliance on
// DwarfDebug away.
uint64_t Attr;
if (Ref < InputDIE.getOffset()) {
// We must have already cloned that DIE.
uint32_t NewRefOffset =
RefUnit->getStartOffset() + NewRefDie->getOffset();
Attr = NewRefOffset;
Die.addValue(DIEAlloc, dwarf::Attribute(AttrSpec.Attr),
dwarf::DW_FORM_ref_addr, DIEInteger(Attr));
} else {
// A forward reference. Note and fixup later.
Attr = 0xBADDEF;
Unit.noteForwardReference(
NewRefDie, RefUnit, Ctxt,
Die.addValue(DIEAlloc, dwarf::Attribute(AttrSpec.Attr),
dwarf::DW_FORM_ref_addr, DIEInteger(Attr)));
}
return U.getRefAddrByteSize();
}
Die.addValue(DIEAlloc, dwarf::Attribute(AttrSpec.Attr),
dwarf::Form(AttrSpec.Form), DIEEntry(*NewRefDie));
return AttrSize;
}
void DWARFLinker::DIECloner::cloneExpression(
DataExtractor &Data, DWARFExpression Expression, const DwarfFile &File,
CompileUnit &Unit, SmallVectorImpl<uint8_t> &OutputBuffer) {
using Encoding = DWARFExpression::Operation::Encoding;
uint64_t OpOffset = 0;
for (auto &Op : Expression) {
auto Description = Op.getDescription();
// DW_OP_const_type is variable-length and has 3
// operands. DWARFExpression thus far only supports 2.
auto Op0 = Description.Op[0];
auto Op1 = Description.Op[1];
if ((Op0 == Encoding::BaseTypeRef && Op1 != Encoding::SizeNA) ||
(Op1 == Encoding::BaseTypeRef && Op0 != Encoding::Size1))
Linker.reportWarning("Unsupported DW_OP encoding.", File);
if ((Op0 == Encoding::BaseTypeRef && Op1 == Encoding::SizeNA) ||
(Op1 == Encoding::BaseTypeRef && Op0 == Encoding::Size1)) {
// This code assumes that the other non-typeref operand fits into 1 byte.
assert(OpOffset < Op.getEndOffset());
uint32_t ULEBsize = Op.getEndOffset() - OpOffset - 1;
assert(ULEBsize <= 16);
// Copy over the operation.
OutputBuffer.push_back(Op.getCode());
uint64_t RefOffset;
if (Op1 == Encoding::SizeNA) {
RefOffset = Op.getRawOperand(0);
} else {
OutputBuffer.push_back(Op.getRawOperand(0));
RefOffset = Op.getRawOperand(1);
}
uint32_t Offset = 0;
// Look up the base type. For DW_OP_convert, the operand may be 0 to
// instead indicate the generic type. The same holds for
// DW_OP_reinterpret, which is currently not supported.
if (RefOffset > 0 || Op.getCode() != dwarf::DW_OP_convert) {
auto RefDie = Unit.getOrigUnit().getDIEForOffset(RefOffset);
uint32_t RefIdx = Unit.getOrigUnit().getDIEIndex(RefDie);
CompileUnit::DIEInfo &Info = Unit.getInfo(RefIdx);
if (DIE *Clone = Info.Clone)
Offset = Clone->getOffset();
else
Linker.reportWarning(
"base type ref doesn't point to DW_TAG_base_type.", File);
}
uint8_t ULEB[16];
unsigned RealSize = encodeULEB128(Offset, ULEB, ULEBsize);
if (RealSize > ULEBsize) {
// Emit the generic type as a fallback.
RealSize = encodeULEB128(0, ULEB, ULEBsize);
Linker.reportWarning("base type ref doesn't fit.", File);
}
assert(RealSize == ULEBsize && "padding failed");
ArrayRef<uint8_t> ULEBbytes(ULEB, ULEBsize);
OutputBuffer.append(ULEBbytes.begin(), ULEBbytes.end());
} else {
// Copy over everything else unmodified.
StringRef Bytes = Data.getData().slice(OpOffset, Op.getEndOffset());
OutputBuffer.append(Bytes.begin(), Bytes.end());
}
OpOffset = Op.getEndOffset();
}
}
unsigned DWARFLinker::DIECloner::cloneBlockAttribute(
DIE &Die, const DwarfFile &File, CompileUnit &Unit, AttributeSpec AttrSpec,
const DWARFFormValue &Val, unsigned AttrSize, bool IsLittleEndian) {
DIEValueList *Attr;
DIEValue Value;
DIELoc *Loc = nullptr;
DIEBlock *Block = nullptr;
if (AttrSpec.Form == dwarf::DW_FORM_exprloc) {
Loc = new (DIEAlloc) DIELoc;
Linker.DIELocs.push_back(Loc);
} else {
Block = new (DIEAlloc) DIEBlock;
Linker.DIEBlocks.push_back(Block);
}
Attr = Loc ? static_cast<DIEValueList *>(Loc)
: static_cast<DIEValueList *>(Block);
if (Loc)
Value = DIEValue(dwarf::Attribute(AttrSpec.Attr),
dwarf::Form(AttrSpec.Form), Loc);
else
Value = DIEValue(dwarf::Attribute(AttrSpec.Attr),
dwarf::Form(AttrSpec.Form), Block);
// If the block is a DWARF Expression, clone it into the temporary
// buffer using cloneExpression(), otherwise copy the data directly.
SmallVector<uint8_t, 32> Buffer;
ArrayRef<uint8_t> Bytes = *Val.getAsBlock();
if (DWARFAttribute::mayHaveLocationDescription(AttrSpec.Attr) &&
(Val.isFormClass(DWARFFormValue::FC_Block) ||
Val.isFormClass(DWARFFormValue::FC_Exprloc))) {
DWARFUnit &OrigUnit = Unit.getOrigUnit();
DataExtractor Data(StringRef((const char *)Bytes.data(), Bytes.size()),
IsLittleEndian, OrigUnit.getAddressByteSize());
DWARFExpression Expr(Data, OrigUnit.getAddressByteSize());
cloneExpression(Data, Expr, File, Unit, Buffer);
Bytes = Buffer;
}
for (auto Byte : Bytes)
Attr->addValue(DIEAlloc, static_cast<dwarf::Attribute>(0),
dwarf::DW_FORM_data1, DIEInteger(Byte));
// FIXME: If DIEBlock and DIELoc just reuses the Size field of
// the DIE class, this "if" could be replaced by
// Attr->setSize(Bytes.size()).
if (Loc)
Loc->setSize(Bytes.size());
else
Block->setSize(Bytes.size());
Die.addValue(DIEAlloc, Value);
return AttrSize;
}
unsigned DWARFLinker::DIECloner::cloneAddressAttribute(
DIE &Die, AttributeSpec AttrSpec, const DWARFFormValue &Val,
const CompileUnit &Unit, AttributesInfo &Info) {
uint64_t Addr = *Val.getAsAddress();
if (LLVM_UNLIKELY(Linker.Options.Update)) {
if (AttrSpec.Attr == dwarf::DW_AT_low_pc)
Info.HasLowPc = true;
Die.addValue(DIEAlloc, dwarf::Attribute(AttrSpec.Attr),
dwarf::Form(AttrSpec.Form), DIEInteger(Addr));
return Unit.getOrigUnit().getAddressByteSize();
}
if (AttrSpec.Attr == dwarf::DW_AT_low_pc) {
if (Die.getTag() == dwarf::DW_TAG_inlined_subroutine ||
Die.getTag() == dwarf::DW_TAG_lexical_block)
// The low_pc of a block or inline subroutine might get
// relocated because it happens to match the low_pc of the
// enclosing subprogram. To prevent issues with that, always use
// the low_pc from the input DIE if relocations have been applied.
Addr = (Info.OrigLowPc != std::numeric_limits<uint64_t>::max()
? Info.OrigLowPc
: Addr) +
Info.PCOffset;
else if (Die.getTag() == dwarf::DW_TAG_compile_unit) {
Addr = Unit.getLowPc();
if (Addr == std::numeric_limits<uint64_t>::max())
return 0;
}
Info.HasLowPc = true;
} else if (AttrSpec.Attr == dwarf::DW_AT_high_pc) {
if (Die.getTag() == dwarf::DW_TAG_compile_unit) {
if (uint64_t HighPc = Unit.getHighPc())
Addr = HighPc;
else
return 0;
} else
// If we have a high_pc recorded for the input DIE, use
// it. Otherwise (when no relocations where applied) just use the
// one we just decoded.
Addr = (Info.OrigHighPc ? Info.OrigHighPc : Addr) + Info.PCOffset;
} else if (AttrSpec.Attr == dwarf::DW_AT_call_return_pc) {
// Relocate a return PC address within a call site entry.
if (Die.getTag() == dwarf::DW_TAG_call_site)
Addr = (Info.OrigCallReturnPc ? Info.OrigCallReturnPc : Addr) +
Info.PCOffset;
} else if (AttrSpec.Attr == dwarf::DW_AT_call_pc) {
// Relocate the address of a branch instruction within a call site entry.
if (Die.getTag() == dwarf::DW_TAG_call_site)
Addr = (Info.OrigCallPc ? Info.OrigCallPc : Addr) + Info.PCOffset;
}
Die.addValue(DIEAlloc, static_cast<dwarf::Attribute>(AttrSpec.Attr),
static_cast<dwarf::Form>(AttrSpec.Form), DIEInteger(Addr));
return Unit.getOrigUnit().getAddressByteSize();
}
unsigned DWARFLinker::DIECloner::cloneScalarAttribute(
DIE &Die, const DWARFDie &InputDIE, const DwarfFile &File,
CompileUnit &Unit, AttributeSpec AttrSpec, const DWARFFormValue &Val,
unsigned AttrSize, AttributesInfo &Info) {
uint64_t Value;
if (LLVM_UNLIKELY(Linker.Options.Update)) {
if (auto OptionalValue = Val.getAsUnsignedConstant())
Value = *OptionalValue;
else if (auto OptionalValue = Val.getAsSignedConstant())
Value = *OptionalValue;
else if (auto OptionalValue = Val.getAsSectionOffset())
Value = *OptionalValue;
else {
Linker.reportWarning(
"Unsupported scalar attribute form. Dropping attribute.", File,
&InputDIE);
return 0;
}
if (AttrSpec.Attr == dwarf::DW_AT_declaration && Value)
Info.IsDeclaration = true;
Die.addValue(DIEAlloc, dwarf::Attribute(AttrSpec.Attr),
dwarf::Form(AttrSpec.Form), DIEInteger(Value));
return AttrSize;
}
if (AttrSpec.Attr == dwarf::DW_AT_high_pc &&
Die.getTag() == dwarf::DW_TAG_compile_unit) {
if (Unit.getLowPc() == -1ULL)
return 0;
// Dwarf >= 4 high_pc is an size, not an address.
Value = Unit.getHighPc() - Unit.getLowPc();
} else if (AttrSpec.Form == dwarf::DW_FORM_sec_offset)
Value = *Val.getAsSectionOffset();
else if (AttrSpec.Form == dwarf::DW_FORM_sdata)
Value = *Val.getAsSignedConstant();
else if (auto OptionalValue = Val.getAsUnsignedConstant())
Value = *OptionalValue;
else {
Linker.reportWarning(
"Unsupported scalar attribute form. Dropping attribute.", File,
&InputDIE);
return 0;
}
PatchLocation Patch =
Die.addValue(DIEAlloc, dwarf::Attribute(AttrSpec.Attr),
dwarf::Form(AttrSpec.Form), DIEInteger(Value));
if (AttrSpec.Attr == dwarf::DW_AT_ranges) {
Unit.noteRangeAttribute(Die, Patch);
Info.HasRanges = true;
}
// A more generic way to check for location attributes would be
// nice, but it's very unlikely that any other attribute needs a
// location list.
// FIXME: use DWARFAttribute::mayHaveLocationDescription().
else if (AttrSpec.Attr == dwarf::DW_AT_location ||
AttrSpec.Attr == dwarf::DW_AT_frame_base) {
Unit.noteLocationAttribute(Patch, Info.PCOffset);
} else if (AttrSpec.Attr == dwarf::DW_AT_declaration && Value)
Info.IsDeclaration = true;
return AttrSize;
}
/// Clone \p InputDIE's attribute described by \p AttrSpec with
/// value \p Val, and add it to \p Die.
/// \returns the size of the cloned attribute.
unsigned DWARFLinker::DIECloner::cloneAttribute(
DIE &Die, const DWARFDie &InputDIE, const DwarfFile &File,
CompileUnit &Unit, OffsetsStringPool &StringPool, const DWARFFormValue &Val,
const AttributeSpec AttrSpec, unsigned AttrSize, AttributesInfo &Info,
bool IsLittleEndian) {
const DWARFUnit &U = Unit.getOrigUnit();
switch (AttrSpec.Form) {
case dwarf::DW_FORM_strp:
case dwarf::DW_FORM_string:
return cloneStringAttribute(Die, AttrSpec, Val, U, StringPool, Info);
case dwarf::DW_FORM_ref_addr:
case dwarf::DW_FORM_ref1:
case dwarf::DW_FORM_ref2:
case dwarf::DW_FORM_ref4:
case dwarf::DW_FORM_ref8:
return cloneDieReferenceAttribute(Die, InputDIE, AttrSpec, AttrSize, Val,
File, Unit);
case dwarf::DW_FORM_block:
case dwarf::DW_FORM_block1:
case dwarf::DW_FORM_block2:
case dwarf::DW_FORM_block4:
case dwarf::DW_FORM_exprloc:
return cloneBlockAttribute(Die, File, Unit, AttrSpec, Val, AttrSize,
IsLittleEndian);
case dwarf::DW_FORM_addr:
return cloneAddressAttribute(Die, AttrSpec, Val, Unit, Info);
case dwarf::DW_FORM_data1:
case dwarf::DW_FORM_data2:
case dwarf::DW_FORM_data4:
case dwarf::DW_FORM_data8:
case dwarf::DW_FORM_udata:
case dwarf::DW_FORM_sdata:
case dwarf::DW_FORM_sec_offset:
case dwarf::DW_FORM_flag:
case dwarf::DW_FORM_flag_present:
return cloneScalarAttribute(Die, InputDIE, File, Unit, AttrSpec, Val,
AttrSize, Info);
default:
Linker.reportWarning(
"Unsupported attribute form in cloneAttribute. Dropping.", File,
&InputDIE);
}
return 0;
}
static bool isObjCSelector(StringRef Name) {
return Name.size() > 2 && (Name[0] == '-' || Name[0] == '+') &&
(Name[1] == '[');
}
void DWARFLinker::DIECloner::addObjCAccelerator(CompileUnit &Unit,
const DIE *Die,
DwarfStringPoolEntryRef Name,
OffsetsStringPool &StringPool,
bool SkipPubSection) {
assert(isObjCSelector(Name.getString()) && "not an objc selector");
// Objective C method or class function.
// "- [Class(Category) selector :withArg ...]"
StringRef ClassNameStart(Name.getString().drop_front(2));
size_t FirstSpace = ClassNameStart.find(' ');
if (FirstSpace == StringRef::npos)
return;
StringRef SelectorStart(ClassNameStart.data() + FirstSpace + 1);
if (!SelectorStart.size())
return;
StringRef Selector(SelectorStart.data(), SelectorStart.size() - 1);
Unit.addNameAccelerator(Die, StringPool.getEntry(Selector), SkipPubSection);
// Add an entry for the class name that points to this
// method/class function.
StringRef ClassName(ClassNameStart.data(), FirstSpace);
Unit.addObjCAccelerator(Die, StringPool.getEntry(ClassName), SkipPubSection);
if (ClassName[ClassName.size() - 1] == ')') {
size_t OpenParens = ClassName.find('(');
if (OpenParens != StringRef::npos) {
StringRef ClassNameNoCategory(ClassName.data(), OpenParens);
Unit.addObjCAccelerator(Die, StringPool.getEntry(ClassNameNoCategory),
SkipPubSection);
std::string MethodNameNoCategory(Name.getString().data(), OpenParens + 2);
// FIXME: The missing space here may be a bug, but
// dsymutil-classic also does it this way.
MethodNameNoCategory.append(std::string(SelectorStart));
Unit.addNameAccelerator(Die, StringPool.getEntry(MethodNameNoCategory),
SkipPubSection);
}
}
}
static bool
shouldSkipAttribute(DWARFAbbreviationDeclaration::AttributeSpec AttrSpec,
uint16_t Tag, bool InDebugMap, bool SkipPC,
bool InFunctionScope) {
switch (AttrSpec.Attr) {
default:
return false;
case dwarf::DW_AT_low_pc:
case dwarf::DW_AT_high_pc:
case dwarf::DW_AT_ranges:
return SkipPC;
case dwarf::DW_AT_location:
case dwarf::DW_AT_frame_base:
// FIXME: for some reason dsymutil-classic keeps the location attributes
// when they are of block type (i.e. not location lists). This is totally
// wrong for globals where we will keep a wrong address. It is mostly
// harmless for locals, but there is no point in keeping these anyway when
// the function wasn't linked.
return (SkipPC || (!InFunctionScope && Tag == dwarf::DW_TAG_variable &&
!InDebugMap)) &&
!DWARFFormValue(AttrSpec.Form).isFormClass(DWARFFormValue::FC_Block);
}
}
DIE *DWARFLinker::DIECloner::cloneDIE(const DWARFDie &InputDIE,
const DwarfFile &File, CompileUnit &Unit,
OffsetsStringPool &StringPool,
int64_t PCOffset, uint32_t OutOffset,
unsigned Flags, bool IsLittleEndian,
DIE *Die) {
DWARFUnit &U = Unit.getOrigUnit();
unsigned Idx = U.getDIEIndex(InputDIE);
CompileUnit::DIEInfo &Info = Unit.getInfo(Idx);
// Should the DIE appear in the output?
if (!Unit.getInfo(Idx).Keep)
return nullptr;
uint64_t Offset = InputDIE.getOffset();
assert(!(Die && Info.Clone) && "Can't supply a DIE and a cloned DIE");
if (!Die) {
// The DIE might have been already created by a forward reference
// (see cloneDieReferenceAttribute()).
if (!Info.Clone)
Info.Clone = DIE::get(DIEAlloc, dwarf::Tag(InputDIE.getTag()));
Die = Info.Clone;
}
assert(Die->getTag() == InputDIE.getTag());
Die->setOffset(OutOffset);
if ((Unit.hasODR() || Unit.isClangModule()) && !Info.Incomplete &&
Die->getTag() != dwarf::DW_TAG_namespace && Info.Ctxt &&
Info.Ctxt != Unit.getInfo(Info.ParentIdx).Ctxt &&
!Info.Ctxt->getCanonicalDIEOffset()) {
// We are about to emit a DIE that is the root of its own valid
// DeclContext tree. Make the current offset the canonical offset
// for this context.
Info.Ctxt->setCanonicalDIEOffset(OutOffset + Unit.getStartOffset());
}
// Extract and clone every attribute.
DWARFDataExtractor Data = U.getDebugInfoExtractor();
// Point to the next DIE (generally there is always at least a NULL
// entry after the current one). If this is a lone
// DW_TAG_compile_unit without any children, point to the next unit.
uint64_t NextOffset = (Idx + 1 < U.getNumDIEs())
? U.getDIEAtIndex(Idx + 1).getOffset()
: U.getNextUnitOffset();
AttributesInfo AttrInfo;
// We could copy the data only if we need to apply a relocation to it. After
// testing, it seems there is no performance downside to doing the copy
// unconditionally, and it makes the code simpler.
SmallString<40> DIECopy(Data.getData().substr(Offset, NextOffset - Offset));
Data =
DWARFDataExtractor(DIECopy, Data.isLittleEndian(), Data.getAddressSize());
// Modify the copy with relocated addresses.
if (ObjFile.Addresses->areRelocationsResolved() &&
ObjFile.Addresses->applyValidRelocs(DIECopy, Offset,
Data.isLittleEndian())) {
// If we applied relocations, we store the value of high_pc that was
// potentially stored in the input DIE. If high_pc is an address
// (Dwarf version == 2), then it might have been relocated to a
// totally unrelated value (because the end address in the object
// file might be start address of another function which got moved
// independently by the linker). The computation of the actual
// high_pc value is done in cloneAddressAttribute().
AttrInfo.OrigHighPc =
dwarf::toAddress(InputDIE.find(dwarf::DW_AT_high_pc), 0);
// Also store the low_pc. It might get relocated in an
// inline_subprogram that happens at the beginning of its
// inlining function.
AttrInfo.OrigLowPc = dwarf::toAddress(InputDIE.find(dwarf::DW_AT_low_pc),
std::numeric_limits<uint64_t>::max());
AttrInfo.OrigCallReturnPc =
dwarf::toAddress(InputDIE.find(dwarf::DW_AT_call_return_pc), 0);
}
// Reset the Offset to 0 as we will be working on the local copy of
// the data.
Offset = 0;
const auto *Abbrev = InputDIE.getAbbreviationDeclarationPtr();
Offset += getULEB128Size(Abbrev->getCode());
// We are entering a subprogram. Get and propagate the PCOffset.
if (Die->getTag() == dwarf::DW_TAG_subprogram)
PCOffset = Info.AddrAdjust;
AttrInfo.PCOffset = PCOffset;
if (Abbrev->getTag() == dwarf::DW_TAG_subprogram) {
Flags |= TF_InFunctionScope;
if (!Info.InDebugMap && LLVM_LIKELY(!Update))
Flags |= TF_SkipPC;
}
bool Copied = false;
for (const auto &AttrSpec : Abbrev->attributes()) {
if (LLVM_LIKELY(!Update) &&
shouldSkipAttribute(AttrSpec, Die->getTag(), Info.InDebugMap,
Flags & TF_SkipPC, Flags & TF_InFunctionScope)) {
DWARFFormValue::skipValue(AttrSpec.Form, Data, &Offset,
U.getFormParams());
// FIXME: dsymutil-classic keeps the old abbreviation around
// even if it's not used. We can remove this (and the copyAbbrev
// helper) as soon as bit-for-bit compatibility is not a goal anymore.
if (!Copied) {
copyAbbrev(*InputDIE.getAbbreviationDeclarationPtr(), Unit.hasODR());
Copied = true;
}
continue;
}
DWARFFormValue Val(AttrSpec.Form);
uint64_t AttrSize = Offset;
Val.extractValue(Data, &Offset, U.getFormParams(), &U);
AttrSize = Offset - AttrSize;
OutOffset += cloneAttribute(*Die, InputDIE, File, Unit, StringPool, Val,
AttrSpec, AttrSize, AttrInfo, IsLittleEndian);
}
// Look for accelerator entries.
uint16_t Tag = InputDIE.getTag();
// FIXME: This is slightly wrong. An inline_subroutine without a
// low_pc, but with AT_ranges might be interesting to get into the
// accelerator tables too. For now stick with dsymutil's behavior.
if ((Info.InDebugMap || AttrInfo.HasLowPc || AttrInfo.HasRanges) &&
Tag != dwarf::DW_TAG_compile_unit &&
getDIENames(InputDIE, AttrInfo, StringPool,
Tag != dwarf::DW_TAG_inlined_subroutine)) {
if (AttrInfo.MangledName && AttrInfo.MangledName != AttrInfo.Name)
Unit.addNameAccelerator(Die, AttrInfo.MangledName,
Tag == dwarf::DW_TAG_inlined_subroutine);
if (AttrInfo.Name) {
if (AttrInfo.NameWithoutTemplate)
Unit.addNameAccelerator(Die, AttrInfo.NameWithoutTemplate,
/* SkipPubSection */ true);
Unit.addNameAccelerator(Die, AttrInfo.Name,
Tag == dwarf::DW_TAG_inlined_subroutine);
}
if (AttrInfo.Name && isObjCSelector(AttrInfo.Name.getString()))
addObjCAccelerator(Unit, Die, AttrInfo.Name, StringPool,
/* SkipPubSection =*/true);
} else if (Tag == dwarf::DW_TAG_namespace) {
if (!AttrInfo.Name)
AttrInfo.Name = StringPool.getEntry("(anonymous namespace)");
Unit.addNamespaceAccelerator(Die, AttrInfo.Name);
} else if (isTypeTag(Tag) && !AttrInfo.IsDeclaration &&
getDIENames(InputDIE, AttrInfo, StringPool) && AttrInfo.Name &&
AttrInfo.Name.getString()[0]) {
uint32_t Hash = hashFullyQualifiedName(InputDIE, Unit, File);
uint64_t RuntimeLang =
dwarf::toUnsigned(InputDIE.find(dwarf::DW_AT_APPLE_runtime_class))
.getValueOr(0);
bool ObjCClassIsImplementation =
(RuntimeLang == dwarf::DW_LANG_ObjC ||
RuntimeLang == dwarf::DW_LANG_ObjC_plus_plus) &&
dwarf::toUnsigned(InputDIE.find(dwarf::DW_AT_APPLE_objc_complete_type))
.getValueOr(0);
Unit.addTypeAccelerator(Die, AttrInfo.Name, ObjCClassIsImplementation,
Hash);
}
// Determine whether there are any children that we want to keep.
bool HasChildren = false;
for (auto Child : InputDIE.children()) {
unsigned Idx = U.getDIEIndex(Child);
if (Unit.getInfo(Idx).Keep) {
HasChildren = true;
break;
}
}
DIEAbbrev NewAbbrev = Die->generateAbbrev();
if (HasChildren)
NewAbbrev.setChildrenFlag(dwarf::DW_CHILDREN_yes);
// Assign a permanent abbrev number
Linker.assignAbbrev(NewAbbrev);
Die->setAbbrevNumber(NewAbbrev.getNumber());
// Add the size of the abbreviation number to the output offset.
OutOffset += getULEB128Size(Die->getAbbrevNumber());
if (!HasChildren) {
// Update our size.
Die->setSize(OutOffset - Die->getOffset());
return Die;
}
// Recursively clone children.
for (auto Child : InputDIE.children()) {
if (DIE *Clone = cloneDIE(Child, File, Unit, StringPool, PCOffset,
OutOffset, Flags, IsLittleEndian)) {
Die->addChild(Clone);
OutOffset = Clone->getOffset() + Clone->getSize();
}
}
// Account for the end of children marker.
OutOffset += sizeof(int8_t);
// Update our size.
Die->setSize(OutOffset - Die->getOffset());
return Die;
}
/// Patch the input object file relevant debug_ranges entries
/// and emit them in the output file. Update the relevant attributes
/// to point at the new entries.
void DWARFLinker::patchRangesForUnit(const CompileUnit &Unit,
DWARFContext &OrigDwarf,
const DwarfFile &File) const {
DWARFDebugRangeList RangeList;
const auto &FunctionRanges = Unit.getFunctionRanges();
unsigned AddressSize = Unit.getOrigUnit().getAddressByteSize();
DWARFDataExtractor RangeExtractor(OrigDwarf.getDWARFObj(),
OrigDwarf.getDWARFObj().getRangesSection(),
OrigDwarf.isLittleEndian(), AddressSize);
auto InvalidRange = FunctionRanges.end(), CurrRange = InvalidRange;
DWARFUnit &OrigUnit = Unit.getOrigUnit();
auto OrigUnitDie = OrigUnit.getUnitDIE(false);
uint64_t OrigLowPc =
dwarf::toAddress(OrigUnitDie.find(dwarf::DW_AT_low_pc), -1ULL);
// Ranges addresses are based on the unit's low_pc. Compute the
// offset we need to apply to adapt to the new unit's low_pc.
int64_t UnitPcOffset = 0;
if (OrigLowPc != -1ULL)
UnitPcOffset = int64_t(OrigLowPc) - Unit.getLowPc();
for (const auto &RangeAttribute : Unit.getRangesAttributes()) {
uint64_t Offset = RangeAttribute.get();
RangeAttribute.set(TheDwarfEmitter->getRangesSectionSize());
if (Error E = RangeList.extract(RangeExtractor, &Offset)) {
llvm::consumeError(std::move(E));
reportWarning("invalid range list ignored.", File);
RangeList.clear();
}
const auto &Entries = RangeList.getEntries();
if (!Entries.empty()) {
const DWARFDebugRangeList::RangeListEntry &First = Entries.front();
if (CurrRange == InvalidRange ||
First.StartAddress + OrigLowPc < CurrRange.start() ||
First.StartAddress + OrigLowPc >= CurrRange.stop()) {
CurrRange = FunctionRanges.find(First.StartAddress + OrigLowPc);
if (CurrRange == InvalidRange ||
CurrRange.start() > First.StartAddress + OrigLowPc) {
reportWarning("no mapping for range.", File);
continue;
}
}
}
TheDwarfEmitter->emitRangesEntries(UnitPcOffset, OrigLowPc, CurrRange,
Entries, AddressSize);
}
}
/// Generate the debug_aranges entries for \p Unit and if the
/// unit has a DW_AT_ranges attribute, also emit the debug_ranges
/// contribution for this attribute.
/// FIXME: this could actually be done right in patchRangesForUnit,
/// but for the sake of initial bit-for-bit compatibility with legacy
/// dsymutil, we have to do it in a delayed pass.
void DWARFLinker::generateUnitRanges(CompileUnit &Unit) const {
auto Attr = Unit.getUnitRangesAttribute();
if (Attr)
Attr->set(TheDwarfEmitter->getRangesSectionSize());
TheDwarfEmitter->emitUnitRangesEntries(Unit, static_cast<bool>(Attr));
}
/// Insert the new line info sequence \p Seq into the current
/// set of already linked line info \p Rows.
static void insertLineSequence(std::vector<DWARFDebugLine::Row> &Seq,
std::vector<DWARFDebugLine::Row> &Rows) {
if (Seq.empty())
return;
if (!Rows.empty() && Rows.back().Address < Seq.front().Address) {
Rows.insert(Rows.end(), Seq.begin(), Seq.end());
Seq.clear();
return;
}
object::SectionedAddress Front = Seq.front().Address;
auto InsertPoint = partition_point(
Rows, [=](const DWARFDebugLine::Row &O) { return O.Address < Front; });
// FIXME: this only removes the unneeded end_sequence if the
// sequences have been inserted in order. Using a global sort like
// described in patchLineTableForUnit() and delaying the end_sequene
// elimination to emitLineTableForUnit() we can get rid of all of them.
if (InsertPoint != Rows.end() && InsertPoint->Address == Front &&
InsertPoint->EndSequence) {
*InsertPoint = Seq.front();
Rows.insert(InsertPoint + 1, Seq.begin() + 1, Seq.end());
} else {
Rows.insert(InsertPoint, Seq.begin(), Seq.end());
}
Seq.clear();
}
static void patchStmtList(DIE &Die, DIEInteger Offset) {
for (auto &V : Die.values())
if (V.getAttribute() == dwarf::DW_AT_stmt_list) {
V = DIEValue(V.getAttribute(), V.getForm(), Offset);
return;
}
llvm_unreachable("Didn't find DW_AT_stmt_list in cloned DIE!");
}
/// Extract the line table for \p Unit from \p OrigDwarf, and
/// recreate a relocated version of these for the address ranges that
/// are present in the binary.
void DWARFLinker::patchLineTableForUnit(CompileUnit &Unit,
DWARFContext &OrigDwarf,
const DwarfFile &File) {
DWARFDie CUDie = Unit.getOrigUnit().getUnitDIE();
auto StmtList = dwarf::toSectionOffset(CUDie.find(dwarf::DW_AT_stmt_list));
if (!StmtList)
return;
// Update the cloned DW_AT_stmt_list with the correct debug_line offset.
if (auto *OutputDIE = Unit.getOutputUnitDIE())
patchStmtList(*OutputDIE,
DIEInteger(TheDwarfEmitter->getLineSectionSize()));
RangesTy &Ranges = File.Addresses->getValidAddressRanges();
// Parse the original line info for the unit.
DWARFDebugLine::LineTable LineTable;
uint64_t StmtOffset = *StmtList;
DWARFDataExtractor LineExtractor(
OrigDwarf.getDWARFObj(), OrigDwarf.getDWARFObj().getLineSection(),
OrigDwarf.isLittleEndian(), Unit.getOrigUnit().getAddressByteSize());
if (needToTranslateStrings())
return TheDwarfEmitter->translateLineTable(LineExtractor, StmtOffset);
if (Error Err =
LineTable.parse(LineExtractor, &StmtOffset, OrigDwarf,
&Unit.getOrigUnit(), OrigDwarf.getWarningHandler()))
OrigDwarf.getWarningHandler()(std::move(Err));
// This vector is the output line table.
std::vector<DWARFDebugLine::Row> NewRows;
NewRows.reserve(LineTable.Rows.size());
// Current sequence of rows being extracted, before being inserted
// in NewRows.
std::vector<DWARFDebugLine::Row> Seq;
const auto &FunctionRanges = Unit.getFunctionRanges();
auto InvalidRange = FunctionRanges.end(), CurrRange = InvalidRange;
// FIXME: This logic is meant to generate exactly the same output as
// Darwin's classic dsymutil. There is a nicer way to implement this
// by simply putting all the relocated line info in NewRows and simply
// sorting NewRows before passing it to emitLineTableForUnit. This
// should be correct as sequences for a function should stay
// together in the sorted output. There are a few corner cases that
// look suspicious though, and that required to implement the logic
// this way. Revisit that once initial validation is finished.
// Iterate over the object file line info and extract the sequences
// that correspond to linked functions.
for (auto &Row : LineTable.Rows) {
// Check whether we stepped out of the range. The range is
// half-open, but consider accept the end address of the range if
// it is marked as end_sequence in the input (because in that
// case, the relocation offset is accurate and that entry won't
// serve as the start of another function).
if (CurrRange == InvalidRange || Row.Address.Address < CurrRange.start() ||
Row.Address.Address > CurrRange.stop() ||
(Row.Address.Address == CurrRange.stop() && !Row.EndSequence)) {
// We just stepped out of a known range. Insert a end_sequence
// corresponding to the end of the range.
uint64_t StopAddress = CurrRange != InvalidRange
? CurrRange.stop() + CurrRange.value()
: -1ULL;
CurrRange = FunctionRanges.find(Row.Address.Address);
bool CurrRangeValid =
CurrRange != InvalidRange && CurrRange.start() <= Row.Address.Address;
if (!CurrRangeValid) {
CurrRange = InvalidRange;
if (StopAddress != -1ULL) {
// Try harder by looking in the Address ranges map.
// There are corner cases where this finds a
// valid entry. It's unclear if this is right or wrong, but
// for now do as dsymutil.
// FIXME: Understand exactly what cases this addresses and
// potentially remove it along with the Ranges map.
auto Range = Ranges.lower_bound(Row.Address.Address);
if (Range != Ranges.begin() && Range != Ranges.end())
--Range;
if (Range != Ranges.end() && Range->first <= Row.Address.Address &&
Range->second.HighPC >= Row.Address.Address) {
StopAddress = Row.Address.Address + Range->second.Offset;
}
}
}
if (StopAddress != -1ULL && !Seq.empty()) {
// Insert end sequence row with the computed end address, but
// the same line as the previous one.
auto NextLine = Seq.back();
NextLine.Address.Address = StopAddress;
NextLine.EndSequence = 1;
NextLine.PrologueEnd = 0;
NextLine.BasicBlock = 0;
NextLine.EpilogueBegin = 0;
Seq.push_back(NextLine);
insertLineSequence(Seq, NewRows);
}
if (!CurrRangeValid)
continue;
}
// Ignore empty sequences.
if (Row.EndSequence && Seq.empty())
continue;
// Relocate row address and add it to the current sequence.
Row.Address.Address += CurrRange.value();
Seq.emplace_back(Row);
if (Row.EndSequence)
insertLineSequence(Seq, NewRows);
}
// Finished extracting, now emit the line tables.
// FIXME: LLVM hard-codes its prologue values. We just copy the
// prologue over and that works because we act as both producer and
// consumer. It would be nicer to have a real configurable line
// table emitter.
if (LineTable.Prologue.getVersion() < 2 ||
LineTable.Prologue.getVersion() > 5 ||
LineTable.Prologue.DefaultIsStmt != DWARF2_LINE_DEFAULT_IS_STMT ||
LineTable.Prologue.OpcodeBase > 13)
reportWarning("line table parameters mismatch. Cannot emit.", File);
else {
uint32_t PrologueEnd = *StmtList + 10 + LineTable.Prologue.PrologueLength;
// DWARF v5 has an extra 2 bytes of information before the header_length
// field.
if (LineTable.Prologue.getVersion() == 5)
PrologueEnd += 2;
StringRef LineData = OrigDwarf.getDWARFObj().getLineSection().Data;
MCDwarfLineTableParams Params;
Params.DWARF2LineOpcodeBase = LineTable.Prologue.OpcodeBase;
Params.DWARF2LineBase = LineTable.Prologue.LineBase;
Params.DWARF2LineRange = LineTable.Prologue.LineRange;
TheDwarfEmitter->emitLineTableForUnit(
Params, LineData.slice(*StmtList + 4, PrologueEnd),
LineTable.Prologue.MinInstLength, NewRows,
Unit.getOrigUnit().getAddressByteSize());
}
}
void DWARFLinker::emitAcceleratorEntriesForUnit(CompileUnit &Unit) {
switch (Options.TheAccelTableKind) {
case AccelTableKind::Apple:
emitAppleAcceleratorEntriesForUnit(Unit);
break;
case AccelTableKind::Dwarf:
emitDwarfAcceleratorEntriesForUnit(Unit);
break;
case AccelTableKind::Default:
llvm_unreachable("The default must be updated to a concrete value.");
break;
}
}
void DWARFLinker::emitAppleAcceleratorEntriesForUnit(CompileUnit &Unit) {
// Add namespaces.
for (const auto &Namespace : Unit.getNamespaces())
AppleNamespaces.addName(Namespace.Name,
Namespace.Die->getOffset() + Unit.getStartOffset());
/// Add names.
TheDwarfEmitter->emitPubNamesForUnit(Unit);
for (const auto &Pubname : Unit.getPubnames())
AppleNames.addName(Pubname.Name,
Pubname.Die->getOffset() + Unit.getStartOffset());
/// Add types.
TheDwarfEmitter->emitPubTypesForUnit(Unit);
for (const auto &Pubtype : Unit.getPubtypes())
AppleTypes.addName(
Pubtype.Name, Pubtype.Die->getOffset() + Unit.getStartOffset(),
Pubtype.Die->getTag(),
Pubtype.ObjcClassImplementation ? dwarf::DW_FLAG_type_implementation
: 0,
Pubtype.QualifiedNameHash);
/// Add ObjC names.
for (const auto &ObjC : Unit.getObjC())
AppleObjc.addName(ObjC.Name, ObjC.Die->getOffset() + Unit.getStartOffset());
}
void DWARFLinker::emitDwarfAcceleratorEntriesForUnit(CompileUnit &Unit) {
for (const auto &Namespace : Unit.getNamespaces())
DebugNames.addName(Namespace.Name, Namespace.Die->getOffset(),
Namespace.Die->getTag(), Unit.getUniqueID());
for (const auto &Pubname : Unit.getPubnames())
DebugNames.addName(Pubname.Name, Pubname.Die->getOffset(),
Pubname.Die->getTag(), Unit.getUniqueID());
for (const auto &Pubtype : Unit.getPubtypes())
DebugNames.addName(Pubtype.Name, Pubtype.Die->getOffset(),
Pubtype.Die->getTag(), Unit.getUniqueID());
}
/// Read the frame info stored in the object, and emit the
/// patched frame descriptions for the resulting file.
///
/// This is actually pretty easy as the data of the CIEs and FDEs can
/// be considered as black boxes and moved as is. The only thing to do
/// is to patch the addresses in the headers.
void DWARFLinker::patchFrameInfoForObject(const DwarfFile &File,
RangesTy &Ranges,
DWARFContext &OrigDwarf,
unsigned AddrSize) {
StringRef FrameData = OrigDwarf.getDWARFObj().getFrameSection().Data;
if (FrameData.empty())
return;
DataExtractor Data(FrameData, OrigDwarf.isLittleEndian(), 0);
uint64_t InputOffset = 0;
// Store the data of the CIEs defined in this object, keyed by their
// offsets.
DenseMap<uint64_t, StringRef> LocalCIES;
while (Data.isValidOffset(InputOffset)) {
uint64_t EntryOffset = InputOffset;
uint32_t InitialLength = Data.getU32(&InputOffset);
if (InitialLength == 0xFFFFFFFF)
return reportWarning("Dwarf64 bits no supported", File);
uint32_t CIEId = Data.getU32(&InputOffset);
if (CIEId == 0xFFFFFFFF) {
// This is a CIE, store it.
StringRef CIEData = FrameData.substr(EntryOffset, InitialLength + 4);
LocalCIES[EntryOffset] = CIEData;
// The -4 is to account for the CIEId we just read.
InputOffset += InitialLength - 4;
continue;
}
uint32_t Loc = Data.getUnsigned(&InputOffset, AddrSize);
// Some compilers seem to emit frame info that doesn't start at
// the function entry point, thus we can't just lookup the address
// in the debug map. Use the AddressInfo's range map to see if the FDE
// describes something that we can relocate.
auto Range = Ranges.upper_bound(Loc);
if (Range != Ranges.begin())
--Range;
if (Range == Ranges.end() || Range->first > Loc ||
Range->second.HighPC <= Loc) {
// The +4 is to account for the size of the InitialLength field itself.
InputOffset = EntryOffset + InitialLength + 4;
continue;
}
// This is an FDE, and we have a mapping.
// Have we already emitted a corresponding CIE?
StringRef CIEData = LocalCIES[CIEId];
if (CIEData.empty())
return reportWarning("Inconsistent debug_frame content. Dropping.", File);
// Look if we already emitted a CIE that corresponds to the
// referenced one (the CIE data is the key of that lookup).
auto IteratorInserted = EmittedCIEs.insert(
std::make_pair(CIEData, TheDwarfEmitter->getFrameSectionSize()));
// If there is no CIE yet for this ID, emit it.
if (IteratorInserted.second ||
// FIXME: dsymutil-classic only caches the last used CIE for
// reuse. Mimic that behavior for now. Just removing that
// second half of the condition and the LastCIEOffset variable
// makes the code DTRT.
LastCIEOffset != IteratorInserted.first->getValue()) {
LastCIEOffset = TheDwarfEmitter->getFrameSectionSize();
IteratorInserted.first->getValue() = LastCIEOffset;
TheDwarfEmitter->emitCIE(CIEData);
}
// Emit the FDE with updated address and CIE pointer.
// (4 + AddrSize) is the size of the CIEId + initial_location
// fields that will get reconstructed by emitFDE().
unsigned FDERemainingBytes = InitialLength - (4 + AddrSize);
TheDwarfEmitter->emitFDE(IteratorInserted.first->getValue(), AddrSize,
Loc + Range->second.Offset,
FrameData.substr(InputOffset, FDERemainingBytes));
InputOffset += FDERemainingBytes;
}
}
void DWARFLinker::DIECloner::copyAbbrev(
const DWARFAbbreviationDeclaration &Abbrev, bool HasODR) {
DIEAbbrev Copy(dwarf::Tag(Abbrev.getTag()),
dwarf::Form(Abbrev.hasChildren()));
for (const auto &Attr : Abbrev.attributes()) {
uint16_t Form = Attr.Form;
if (HasODR && isODRAttribute(Attr.Attr))
Form = dwarf::DW_FORM_ref_addr;
Copy.AddAttribute(dwarf::Attribute(Attr.Attr), dwarf::Form(Form));
}
Linker.assignAbbrev(Copy);
}
uint32_t DWARFLinker::DIECloner::hashFullyQualifiedName(DWARFDie DIE,
CompileUnit &U,
const DwarfFile &File,
int ChildRecurseDepth) {
const char *Name = nullptr;
DWARFUnit *OrigUnit = &U.getOrigUnit();
CompileUnit *CU = &U;
Optional<DWARFFormValue> Ref;
while (1) {
if (const char *CurrentName = DIE.getName(DINameKind::ShortName))
Name = CurrentName;
if (!(Ref = DIE.find(dwarf::DW_AT_specification)) &&
!(Ref = DIE.find(dwarf::DW_AT_abstract_origin)))
break;
if (!Ref->isFormClass(DWARFFormValue::FC_Reference))
break;
CompileUnit *RefCU;
if (auto RefDIE =
Linker.resolveDIEReference(File, CompileUnits, *Ref, DIE, RefCU)) {
CU = RefCU;
OrigUnit = &RefCU->getOrigUnit();
DIE = RefDIE;
}
}
unsigned Idx = OrigUnit->getDIEIndex(DIE);
if (!Name && DIE.getTag() == dwarf::DW_TAG_namespace)
Name = "(anonymous namespace)";
if (CU->getInfo(Idx).ParentIdx == 0 ||
// FIXME: dsymutil-classic compatibility. Ignore modules.
CU->getOrigUnit().getDIEAtIndex(CU->getInfo(Idx).ParentIdx).getTag() ==
dwarf::DW_TAG_module)
return djbHash(Name ? Name : "", djbHash(ChildRecurseDepth ? "" : "::"));
DWARFDie Die = OrigUnit->getDIEAtIndex(CU->getInfo(Idx).ParentIdx);
return djbHash(
(Name ? Name : ""),
djbHash((Name ? "::" : ""),
hashFullyQualifiedName(Die, *CU, File, ++ChildRecurseDepth)));
}
static uint64_t getDwoId(const DWARFDie &CUDie, const DWARFUnit &Unit) {
auto DwoId = dwarf::toUnsigned(
CUDie.find({dwarf::DW_AT_dwo_id, dwarf::DW_AT_GNU_dwo_id}));
if (DwoId)
return *DwoId;
return 0;
}
static std::string remapPath(StringRef Path,
const objectPrefixMap &ObjectPrefixMap) {
for (const auto &Entry : ObjectPrefixMap)
if (Path.startswith(Entry.first))
return (Twine(Entry.second) + Path.substr(Entry.first.size())).str();
return Path.str();
}
bool DWARFLinker::registerModuleReference(
DWARFDie CUDie, const DWARFUnit &Unit, const DwarfFile &File,
OffsetsStringPool &StringPool, UniquingStringPool &UniquingStringPool,
DeclContextTree &ODRContexts, uint64_t ModulesEndOffset, unsigned &UnitID,
bool IsLittleEndian, unsigned Indent, bool Quiet) {
std::string PCMfile = dwarf::toString(
CUDie.find({dwarf::DW_AT_dwo_name, dwarf::DW_AT_GNU_dwo_name}), "");
if (PCMfile.empty())
return false;
if (Options.ObjectPrefixMap)
PCMfile = remapPath(PCMfile, *Options.ObjectPrefixMap);
// Clang module DWARF skeleton CUs abuse this for the path to the module.
uint64_t DwoId = getDwoId(CUDie, Unit);
std::string Name = dwarf::toString(CUDie.find(dwarf::DW_AT_name), "");
if (Name.empty()) {
if (!Quiet)
reportWarning("Anonymous module skeleton CU for " + PCMfile, File);
return true;
}
if (!Quiet && Options.Verbose) {
outs().indent(Indent);
outs() << "Found clang module reference " << PCMfile;
}
auto Cached = ClangModules.find(PCMfile);
if (Cached != ClangModules.end()) {
// FIXME: Until PR27449 (https://llvm.org/bugs/show_bug.cgi?id=27449) is
// fixed in clang, only warn about DWO_id mismatches in verbose mode.
// ASTFileSignatures will change randomly when a module is rebuilt.
if (!Quiet && Options.Verbose && (Cached->second != DwoId))
reportWarning(Twine("hash mismatch: this object file was built against a "
"different version of the module ") +
PCMfile,
File);
if (!Quiet && Options.Verbose)
outs() << " [cached].\n";
return true;
}
if (!Quiet && Options.Verbose)
outs() << " ...\n";
// Cyclic dependencies are disallowed by Clang, but we still
// shouldn't run into an infinite loop, so mark it as processed now.
ClangModules.insert({PCMfile, DwoId});
if (Error E =
loadClangModule(CUDie, PCMfile, Name, DwoId, File, StringPool,
UniquingStringPool, ODRContexts, ModulesEndOffset,
UnitID, IsLittleEndian, Indent + 2, Quiet)) {
consumeError(std::move(E));
return false;
}
return true;
}
Error DWARFLinker::loadClangModule(
DWARFDie CUDie, StringRef Filename, StringRef ModuleName, uint64_t DwoId,
const DwarfFile &File, OffsetsStringPool &StringPool,
UniquingStringPool &UniquingStringPool, DeclContextTree &ODRContexts,
uint64_t ModulesEndOffset, unsigned &UnitID, bool IsLittleEndian,
unsigned Indent, bool Quiet) {
/// Using a SmallString<0> because loadClangModule() is recursive.
SmallString<0> Path(Options.PrependPath);
if (sys::path::is_relative(Filename))
resolveRelativeObjectPath(Path, CUDie);
sys::path::append(Path, Filename);
// Don't use the cached binary holder because we have no thread-safety
// guarantee and the lifetime is limited.
if (Options.ObjFileLoader == nullptr)
return Error::success();
auto ErrOrObj = Options.ObjFileLoader(File.FileName, Path);
if (!ErrOrObj)
return Error::success();
std::unique_ptr<CompileUnit> Unit;
for (const auto &CU : ErrOrObj->Dwarf->compile_units()) {
updateDwarfVersion(CU->getVersion());
// Recursively get all modules imported by this one.
auto CUDie = CU->getUnitDIE(false);
if (!CUDie)
continue;
if (!registerModuleReference(
CUDie, *CU, File, StringPool, UniquingStringPool, ODRContexts,
ModulesEndOffset, UnitID, IsLittleEndian, Indent, Quiet)) {
if (Unit) {
std::string Err =
(Filename +
": Clang modules are expected to have exactly 1 compile unit.\n")
.str();
reportError(Err, File);
return make_error<StringError>(Err, inconvertibleErrorCode());
}
// FIXME: Until PR27449 (https://llvm.org/bugs/show_bug.cgi?id=27449) is
// fixed in clang, only warn about DWO_id mismatches in verbose mode.
// ASTFileSignatures will change randomly when a module is rebuilt.
uint64_t PCMDwoId = getDwoId(CUDie, *CU);
if (PCMDwoId != DwoId) {
if (!Quiet && Options.Verbose)
reportWarning(
Twine("hash mismatch: this object file was built against a "
"different version of the module ") +
Filename,
File);
// Update the cache entry with the DwoId of the module loaded from disk.
ClangModules[Filename] = PCMDwoId;
}
// Add this module.
Unit = std::make_unique<CompileUnit>(*CU, UnitID++, !Options.NoODR,
ModuleName);
Unit->setHasInterestingContent();
analyzeContextInfo(CUDie, 0, *Unit, &ODRContexts.getRoot(),
UniquingStringPool, ODRContexts, ModulesEndOffset,
Options.ParseableSwiftInterfaces,
[&](const Twine &Warning, const DWARFDie &DIE) {
reportWarning(Warning, File, &DIE);
});
// Keep everything.
Unit->markEverythingAsKept();
}
}
if (!Unit->getOrigUnit().getUnitDIE().hasChildren())
return Error::success();
if (!Quiet && Options.Verbose) {
outs().indent(Indent);
outs() << "cloning .debug_info from " << Filename << "\n";
}
UnitListTy CompileUnits;
CompileUnits.push_back(std::move(Unit));
assert(TheDwarfEmitter);
DIECloner(*this, TheDwarfEmitter, *ErrOrObj, DIEAlloc, CompileUnits,
Options.Update)
.cloneAllCompileUnits(*(ErrOrObj->Dwarf), File, StringPool,
IsLittleEndian);
return Error::success();
}
void DWARFLinker::DIECloner::cloneAllCompileUnits(DWARFContext &DwarfContext,
const DwarfFile &File,
OffsetsStringPool &StringPool,
bool IsLittleEndian) {
uint64_t OutputDebugInfoSize =
Linker.Options.NoOutput ? 0 : Emitter->getDebugInfoSectionSize();
for (auto &CurrentUnit : CompileUnits) {
auto InputDIE = CurrentUnit->getOrigUnit().getUnitDIE();
CurrentUnit->setStartOffset(OutputDebugInfoSize);
if (!InputDIE) {
OutputDebugInfoSize = CurrentUnit->computeNextUnitOffset();
continue;
}
if (CurrentUnit->getInfo(0).Keep) {
// Clone the InputDIE into your Unit DIE in our compile unit since it
// already has a DIE inside of it.
CurrentUnit->createOutputDIE();
cloneDIE(InputDIE, File, *CurrentUnit, StringPool, 0 /* PC offset */,
11 /* Unit Header size */, 0, IsLittleEndian,
CurrentUnit->getOutputUnitDIE());
}
OutputDebugInfoSize = CurrentUnit->computeNextUnitOffset();
if (!Linker.Options.NoOutput) {
assert(Emitter);
if (LLVM_LIKELY(!Linker.Options.Update) ||
Linker.needToTranslateStrings())
Linker.patchLineTableForUnit(*CurrentUnit, DwarfContext, File);
Linker.emitAcceleratorEntriesForUnit(*CurrentUnit);
if (LLVM_UNLIKELY(Linker.Options.Update))
continue;
Linker.patchRangesForUnit(*CurrentUnit, DwarfContext, File);
auto ProcessExpr = [&](StringRef Bytes,
SmallVectorImpl<uint8_t> &Buffer) {
DWARFUnit &OrigUnit = CurrentUnit->getOrigUnit();
DataExtractor Data(Bytes, IsLittleEndian,
OrigUnit.getAddressByteSize());
cloneExpression(Data,
DWARFExpression(Data, OrigUnit.getAddressByteSize()),
File, *CurrentUnit, Buffer);
};
Emitter->emitLocationsForUnit(*CurrentUnit, DwarfContext, ProcessExpr);
}
}
if (!Linker.Options.NoOutput) {
assert(Emitter);
// Emit all the compile unit's debug information.
for (auto &CurrentUnit : CompileUnits) {
if (LLVM_LIKELY(!Linker.Options.Update))
Linker.generateUnitRanges(*CurrentUnit);
CurrentUnit->fixupForwardReferences();
if (!CurrentUnit->getOutputUnitDIE())
continue;
assert(Emitter->getDebugInfoSectionSize() ==
CurrentUnit->getStartOffset());
Emitter->emitCompileUnitHeader(*CurrentUnit);
Emitter->emitDIE(*CurrentUnit->getOutputUnitDIE());
assert(Emitter->getDebugInfoSectionSize() ==
CurrentUnit->computeNextUnitOffset());
}
}
}
void DWARFLinker::updateAccelKind(DWARFContext &Dwarf) {
if (Options.TheAccelTableKind != AccelTableKind::Default)
return;
auto &DwarfObj = Dwarf.getDWARFObj();
if (!AtLeastOneDwarfAccelTable &&
(!DwarfObj.getAppleNamesSection().Data.empty() ||
!DwarfObj.getAppleTypesSection().Data.empty() ||
!DwarfObj.getAppleNamespacesSection().Data.empty() ||
!DwarfObj.getAppleObjCSection().Data.empty())) {
AtLeastOneAppleAccelTable = true;
}
if (!AtLeastOneDwarfAccelTable && !DwarfObj.getNamesSection().Data.empty()) {
AtLeastOneDwarfAccelTable = true;
}
}
bool DWARFLinker::emitPaperTrailWarnings(const DwarfFile &File,
OffsetsStringPool &StringPool) {
if (File.Warnings.empty())
return false;
DIE *CUDie = DIE::get(DIEAlloc, dwarf::DW_TAG_compile_unit);
CUDie->setOffset(11);
StringRef Producer;
StringRef WarningHeader;
switch (DwarfLinkerClientID) {
case DwarfLinkerClient::Dsymutil:
Producer = StringPool.internString("dsymutil");
WarningHeader = "dsymutil_warning";
break;
default:
Producer = StringPool.internString("dwarfopt");
WarningHeader = "dwarfopt_warning";
break;
}
StringRef FileName = StringPool.internString(File.FileName);
CUDie->addValue(DIEAlloc, dwarf::DW_AT_producer, dwarf::DW_FORM_strp,
DIEInteger(StringPool.getStringOffset(Producer)));
DIEBlock *String = new (DIEAlloc) DIEBlock();
DIEBlocks.push_back(String);
for (auto &C : FileName)
String->addValue(DIEAlloc, dwarf::Attribute(0), dwarf::DW_FORM_data1,
DIEInteger(C));
String->addValue(DIEAlloc, dwarf::Attribute(0), dwarf::DW_FORM_data1,
DIEInteger(0));
CUDie->addValue(DIEAlloc, dwarf::DW_AT_name, dwarf::DW_FORM_string, String);
for (const auto &Warning : File.Warnings) {
DIE &ConstDie = CUDie->addChild(DIE::get(DIEAlloc, dwarf::DW_TAG_constant));
ConstDie.addValue(DIEAlloc, dwarf::DW_AT_name, dwarf::DW_FORM_strp,
DIEInteger(StringPool.getStringOffset(WarningHeader)));
ConstDie.addValue(DIEAlloc, dwarf::DW_AT_artificial, dwarf::DW_FORM_flag,
DIEInteger(1));
ConstDie.addValue(DIEAlloc, dwarf::DW_AT_const_value, dwarf::DW_FORM_strp,
DIEInteger(StringPool.getStringOffset(Warning)));
}
unsigned Size = 4 /* FORM_strp */ + FileName.size() + 1 +
File.Warnings.size() * (4 + 1 + 4) + 1 /* End of children */;
DIEAbbrev Abbrev = CUDie->generateAbbrev();
assignAbbrev(Abbrev);
CUDie->setAbbrevNumber(Abbrev.getNumber());
Size += getULEB128Size(Abbrev.getNumber());
// Abbreviation ordering needed for classic compatibility.
for (auto &Child : CUDie->children()) {
Abbrev = Child.generateAbbrev();
assignAbbrev(Abbrev);
Child.setAbbrevNumber(Abbrev.getNumber());
Size += getULEB128Size(Abbrev.getNumber());
}
CUDie->setSize(Size);
TheDwarfEmitter->emitPaperTrailWarningsDie(*CUDie);
return true;
}
void DWARFLinker::copyInvariantDebugSection(DWARFContext &Dwarf) {
if (!needToTranslateStrings())
TheDwarfEmitter->emitSectionContents(
Dwarf.getDWARFObj().getLineSection().Data, "debug_line");
TheDwarfEmitter->emitSectionContents(Dwarf.getDWARFObj().getLocSection().Data,
"debug_loc");
TheDwarfEmitter->emitSectionContents(
Dwarf.getDWARFObj().getRangesSection().Data, "debug_ranges");
TheDwarfEmitter->emitSectionContents(
Dwarf.getDWARFObj().getFrameSection().Data, "debug_frame");
TheDwarfEmitter->emitSectionContents(Dwarf.getDWARFObj().getArangesSection(),
"debug_aranges");
}
void DWARFLinker::addObjectFile(DwarfFile &File) {
ObjectContexts.emplace_back(LinkContext(File));
if (ObjectContexts.back().File.Dwarf)
updateAccelKind(*ObjectContexts.back().File.Dwarf);
}
bool DWARFLinker::link() {
assert(Options.NoOutput || TheDwarfEmitter);
// A unique ID that identifies each compile unit.
unsigned UnitID = 0;
// First populate the data structure we need for each iteration of the
// parallel loop.
unsigned NumObjects = ObjectContexts.size();
// This Dwarf string pool which is only used for uniquing. This one should
// never be used for offsets as its not thread-safe or predictable.
UniquingStringPool UniquingStringPool(nullptr, true);
// This Dwarf string pool which is used for emission. It must be used
// serially as the order of calling getStringOffset matters for
// reproducibility.
OffsetsStringPool OffsetsStringPool(StringsTranslator, true);
// ODR Contexts for the optimize.
DeclContextTree ODRContexts;
// If we haven't decided on an accelerator table kind yet, we base ourselves
// on the DWARF we have seen so far. At this point we haven't pulled in debug
// information from modules yet, so it is technically possible that they
// would affect the decision. However, as they're built with the same
// compiler and flags, it is safe to assume that they will follow the
// decision made here.
if (Options.TheAccelTableKind == AccelTableKind::Default) {
if (AtLeastOneDwarfAccelTable && !AtLeastOneAppleAccelTable)
Options.TheAccelTableKind = AccelTableKind::Dwarf;
else
Options.TheAccelTableKind = AccelTableKind::Apple;
}
for (LinkContext &OptContext : ObjectContexts) {
if (Options.Verbose) {
if (DwarfLinkerClientID == DwarfLinkerClient::Dsymutil)
outs() << "DEBUG MAP OBJECT: " << OptContext.File.FileName << "\n";
else
outs() << "OBJECT FILE: " << OptContext.File.FileName << "\n";
}
if (emitPaperTrailWarnings(OptContext.File, OffsetsStringPool))
continue;
if (!OptContext.File.Dwarf)
continue;
// Look for relocations that correspond to address map entries.
// there was findvalidrelocations previously ... probably we need to gather
// info here
if (LLVM_LIKELY(!Options.Update) &&
!OptContext.File.Addresses->hasValidRelocs()) {
if (Options.Verbose)
outs() << "No valid relocations found. Skipping.\n";
// Set "Skip" flag as a signal to other loops that we should not
// process this iteration.
OptContext.Skip = true;
continue;
}
// Setup access to the debug info.
if (!OptContext.File.Dwarf)
continue;
// In a first phase, just read in the debug info and load all clang modules.
OptContext.CompileUnits.reserve(
OptContext.File.Dwarf->getNumCompileUnits());
for (const auto &CU : OptContext.File.Dwarf->compile_units()) {
updateDwarfVersion(CU->getVersion());
auto CUDie = CU->getUnitDIE(false);
if (Options.Verbose) {
outs() << "Input compilation unit:";
DIDumpOptions DumpOpts;
DumpOpts.ChildRecurseDepth = 0;
DumpOpts.Verbose = Options.Verbose;
CUDie.dump(outs(), 0, DumpOpts);
}
if (CUDie && !LLVM_UNLIKELY(Options.Update))
registerModuleReference(CUDie, *CU, OptContext.File, OffsetsStringPool,
UniquingStringPool, ODRContexts, 0, UnitID,
OptContext.File.Dwarf->isLittleEndian());
}
}
// If we haven't seen any CUs, pick an arbitrary valid Dwarf version anyway.
if (MaxDwarfVersion == 0)
MaxDwarfVersion = 3;
// At this point we know how much data we have emitted. We use this value to
// compare canonical DIE offsets in analyzeContextInfo to see if a definition
// is already emitted, without being affected by canonical die offsets set
// later. This prevents undeterminism when analyze and clone execute
// concurrently, as clone set the canonical DIE offset and analyze reads it.
const uint64_t ModulesEndOffset =
Options.NoOutput ? 0 : TheDwarfEmitter->getDebugInfoSectionSize();
// These variables manage the list of processed object files.
// The mutex and condition variable are to ensure that this is thread safe.
std::mutex ProcessedFilesMutex;
std::condition_variable ProcessedFilesConditionVariable;
BitVector ProcessedFiles(NumObjects, false);
// Analyzing the context info is particularly expensive so it is executed in
// parallel with emitting the previous compile unit.
auto AnalyzeLambda = [&](size_t I) {
auto &Context = ObjectContexts[I];
if (Context.Skip || !Context.File.Dwarf)
return;
for (const auto &CU : Context.File.Dwarf->compile_units()) {
updateDwarfVersion(CU->getVersion());
// The !registerModuleReference() condition effectively skips
// over fully resolved skeleton units. This second pass of
// registerModuleReferences doesn't do any new work, but it
// will collect top-level errors, which are suppressed. Module
// warnings were already displayed in the first iteration.
bool Quiet = true;
auto CUDie = CU->getUnitDIE(false);
if (!CUDie || LLVM_UNLIKELY(Options.Update) ||
!registerModuleReference(CUDie, *CU, Context.File, OffsetsStringPool,
UniquingStringPool, ODRContexts,
ModulesEndOffset, UnitID, Quiet)) {
Context.CompileUnits.push_back(std::make_unique<CompileUnit>(
*CU, UnitID++, !Options.NoODR && !Options.Update, ""));
}
}
// Now build the DIE parent links that we will use during the next phase.
for (auto &CurrentUnit : Context.CompileUnits) {
auto CUDie = CurrentUnit->getOrigUnit().getUnitDIE();
if (!CUDie)
continue;
analyzeContextInfo(CurrentUnit->getOrigUnit().getUnitDIE(), 0,
*CurrentUnit, &ODRContexts.getRoot(),
UniquingStringPool, ODRContexts, ModulesEndOffset,
Options.ParseableSwiftInterfaces,
[&](const Twine &Warning, const DWARFDie &DIE) {
reportWarning(Warning, Context.File, &DIE);
});
}
};
// And then the remaining work in serial again.
// Note, although this loop runs in serial, it can run in parallel with
// the analyzeContextInfo loop so long as we process files with indices >=
// than those processed by analyzeContextInfo.
auto CloneLambda = [&](size_t I) {
auto &OptContext = ObjectContexts[I];
if (OptContext.Skip || !OptContext.File.Dwarf)
return;
// Then mark all the DIEs that need to be present in the generated output
// and collect some information about them.
// Note that this loop can not be merged with the previous one because
// cross-cu references require the ParentIdx to be setup for every CU in
// the object file before calling this.
if (LLVM_UNLIKELY(Options.Update)) {
for (auto &CurrentUnit : OptContext.CompileUnits)
CurrentUnit->markEverythingAsKept();
copyInvariantDebugSection(*OptContext.File.Dwarf);
} else {
for (auto &CurrentUnit : OptContext.CompileUnits)
lookForDIEsToKeep(*OptContext.File.Addresses,
OptContext.File.Addresses->getValidAddressRanges(),
OptContext.CompileUnits,
CurrentUnit->getOrigUnit().getUnitDIE(),
OptContext.File, *CurrentUnit, 0);
}
// The calls to applyValidRelocs inside cloneDIE will walk the reloc
// array again (in the same way findValidRelocsInDebugInfo() did). We
// need to reset the NextValidReloc index to the beginning.
if (OptContext.File.Addresses->hasValidRelocs() ||
LLVM_UNLIKELY(Options.Update)) {
DIECloner(*this, TheDwarfEmitter, OptContext.File, DIEAlloc,
OptContext.CompileUnits, Options.Update)
.cloneAllCompileUnits(*OptContext.File.Dwarf, OptContext.File,
OffsetsStringPool,
OptContext.File.Dwarf->isLittleEndian());
}
if (!Options.NoOutput && !OptContext.CompileUnits.empty() &&
LLVM_LIKELY(!Options.Update))
patchFrameInfoForObject(
OptContext.File, OptContext.File.Addresses->getValidAddressRanges(),
*OptContext.File.Dwarf,
OptContext.CompileUnits[0]->getOrigUnit().getAddressByteSize());
// Clean-up before starting working on the next object.
cleanupAuxiliarryData(OptContext);
};
auto EmitLambda = [&]() {
// Emit everything that's global.
if (!Options.NoOutput) {
TheDwarfEmitter->emitAbbrevs(Abbreviations, MaxDwarfVersion);
TheDwarfEmitter->emitStrings(OffsetsStringPool);
switch (Options.TheAccelTableKind) {
case AccelTableKind::Apple:
TheDwarfEmitter->emitAppleNames(AppleNames);
TheDwarfEmitter->emitAppleNamespaces(AppleNamespaces);
TheDwarfEmitter->emitAppleTypes(AppleTypes);
TheDwarfEmitter->emitAppleObjc(AppleObjc);
break;
case AccelTableKind::Dwarf:
TheDwarfEmitter->emitDebugNames(DebugNames);
break;
case AccelTableKind::Default:
llvm_unreachable("Default should have already been resolved.");
break;
}
}
};
auto AnalyzeAll = [&]() {
for (unsigned I = 0, E = NumObjects; I != E; ++I) {
AnalyzeLambda(I);
std::unique_lock<std::mutex> LockGuard(ProcessedFilesMutex);
ProcessedFiles.set(I);
ProcessedFilesConditionVariable.notify_one();
}
};
auto CloneAll = [&]() {
for (unsigned I = 0, E = NumObjects; I != E; ++I) {
{
std::unique_lock<std::mutex> LockGuard(ProcessedFilesMutex);
if (!ProcessedFiles[I]) {
ProcessedFilesConditionVariable.wait(
LockGuard, [&]() { return ProcessedFiles[I]; });
}
}
CloneLambda(I);
}
EmitLambda();
};
// To limit memory usage in the single threaded case, analyze and clone are
// run sequentially so the OptContext is freed after processing each object
// in endDebugObject.
if (Options.Threads == 1) {
for (unsigned I = 0, E = NumObjects; I != E; ++I) {
AnalyzeLambda(I);
CloneLambda(I);
}
EmitLambda();
} else {
ThreadPool Pool(hardware_concurrency(2));
Pool.async(AnalyzeAll);
Pool.async(CloneAll);
Pool.wait();
}
return true;
}
} // namespace llvm
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