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//===- DWARFLinkerDeclContext.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/DWARFLinkerDeclContext.h"
#include "llvm/DWARFLinker/DWARFLinkerCompileUnit.h"
#include "llvm/DebugInfo/DWARF/DWARFContext.h"
#include "llvm/DebugInfo/DWARF/DWARFDie.h"
#include "llvm/DebugInfo/DWARF/DWARFUnit.h"
namespace llvm {
/// Set the last DIE/CU a context was seen in and, possibly invalidate the
/// context if it is ambiguous.
///
/// In the current implementation, we don't handle overloaded functions well,
/// because the argument types are not taken into account when computing the
/// DeclContext tree.
///
/// Some of this is mitigated byt using mangled names that do contain the
/// arguments types, but sometimes (e.g. with function templates) we don't have
/// that. In that case, just do not unique anything that refers to the contexts
/// we are not able to distinguish.
///
/// If a context that is not a namespace appears twice in the same CU, we know
/// it is ambiguous. Make it invalid.
bool DeclContext::setLastSeenDIE(CompileUnit &U, const DWARFDie &Die) {
if (LastSeenCompileUnitID == U.getUniqueID()) {
DWARFUnit &OrigUnit = U.getOrigUnit();
uint32_t FirstIdx = OrigUnit.getDIEIndex(LastSeenDIE);
U.getInfo(FirstIdx).Ctxt = nullptr;
return false;
}
LastSeenCompileUnitID = U.getUniqueID();
LastSeenDIE = Die;
return true;
}
PointerIntPair<DeclContext *, 1>
DeclContextTree::getChildDeclContext(DeclContext &Context, const DWARFDie &DIE,
CompileUnit &U, bool InClangModule) {
unsigned Tag = DIE.getTag();
// FIXME: dsymutil-classic compat: We should bail out here if we
// have a specification or an abstract_origin. We will get the
// parent context wrong here.
switch (Tag) {
default:
// By default stop gathering child contexts.
return PointerIntPair<DeclContext *, 1>(nullptr);
case dwarf::DW_TAG_module:
break;
case dwarf::DW_TAG_compile_unit:
return PointerIntPair<DeclContext *, 1>(&Context);
case dwarf::DW_TAG_subprogram:
// Do not unique anything inside CU local functions.
if ((Context.getTag() == dwarf::DW_TAG_namespace ||
Context.getTag() == dwarf::DW_TAG_compile_unit) &&
!dwarf::toUnsigned(DIE.find(dwarf::DW_AT_external), 0))
return PointerIntPair<DeclContext *, 1>(nullptr);
[[fallthrough]];
case dwarf::DW_TAG_member:
case dwarf::DW_TAG_namespace:
case dwarf::DW_TAG_structure_type:
case dwarf::DW_TAG_class_type:
case dwarf::DW_TAG_union_type:
case dwarf::DW_TAG_enumeration_type:
case dwarf::DW_TAG_typedef:
// Artificial things might be ambiguous, because they might be created on
// demand. For example implicitly defined constructors are ambiguous
// because of the way we identify contexts, and they won't be generated
// every time everywhere.
if (dwarf::toUnsigned(DIE.find(dwarf::DW_AT_artificial), 0))
return PointerIntPair<DeclContext *, 1>(nullptr);
break;
}
StringRef NameRef;
StringRef FileRef;
if (const char *LinkageName = DIE.getLinkageName())
NameRef = StringPool.internString(LinkageName);
else if (const char *ShortName = DIE.getShortName())
NameRef = StringPool.internString(ShortName);
bool IsAnonymousNamespace = NameRef.empty() && Tag == dwarf::DW_TAG_namespace;
if (IsAnonymousNamespace) {
// FIXME: For dsymutil-classic compatibility. I think uniquing within
// anonymous namespaces is wrong. There is no ODR guarantee there.
NameRef = "(anonymous namespace)";
}
if (Tag != dwarf::DW_TAG_class_type && Tag != dwarf::DW_TAG_structure_type &&
Tag != dwarf::DW_TAG_union_type &&
Tag != dwarf::DW_TAG_enumeration_type && NameRef.empty())
return PointerIntPair<DeclContext *, 1>(nullptr);
unsigned Line = 0;
unsigned ByteSize = std::numeric_limits<uint32_t>::max();
if (!InClangModule) {
// Gather some discriminating data about the DeclContext we will be
// creating: File, line number and byte size. This shouldn't be necessary,
// because the ODR is just about names, but given that we do some
// approximations with overloaded functions and anonymous namespaces, use
// these additional data points to make the process safer.
//
// This is disabled for clang modules, because forward declarations of
// module-defined types do not have a file and line.
ByteSize = dwarf::toUnsigned(DIE.find(dwarf::DW_AT_byte_size),
std::numeric_limits<uint64_t>::max());
if (Tag != dwarf::DW_TAG_namespace || IsAnonymousNamespace) {
if (unsigned FileNum =
dwarf::toUnsigned(DIE.find(dwarf::DW_AT_decl_file), 0)) {
if (const auto *LT = U.getOrigUnit().getContext().getLineTableForUnit(
&U.getOrigUnit())) {
// FIXME: dsymutil-classic compatibility. I'd rather not
// unique anything in anonymous namespaces, but if we do, then
// verify that the file and line correspond.
if (IsAnonymousNamespace)
FileNum = 1;
if (LT->hasFileAtIndex(FileNum)) {
Line = dwarf::toUnsigned(DIE.find(dwarf::DW_AT_decl_line), 0);
// Cache the resolved paths based on the index in the line table,
// because calling realpath is expensive.
FileRef = getResolvedPath(U, FileNum, *LT);
}
}
}
}
}
if (!Line && NameRef.empty())
return PointerIntPair<DeclContext *, 1>(nullptr);
// We hash NameRef, which is the mangled name, in order to get most
// overloaded functions resolve correctly.
//
// Strictly speaking, hashing the Tag is only necessary for a
// DW_TAG_module, to prevent uniquing of a module and a namespace
// with the same name.
//
// FIXME: dsymutil-classic won't unique the same type presented
// once as a struct and once as a class. Using the Tag in the fully
// qualified name hash to get the same effect.
unsigned Hash = hash_combine(Context.getQualifiedNameHash(), Tag, NameRef);
// FIXME: dsymutil-classic compatibility: when we don't have a name,
// use the filename.
if (IsAnonymousNamespace)
Hash = hash_combine(Hash, FileRef);
// Now look if this context already exists.
DeclContext Key(Hash, Line, ByteSize, Tag, NameRef, FileRef, Context);
auto ContextIter = Contexts.find(&Key);
if (ContextIter == Contexts.end()) {
// The context wasn't found.
bool Inserted;
DeclContext *NewContext =
new (Allocator) DeclContext(Hash, Line, ByteSize, Tag, NameRef, FileRef,
Context, DIE, U.getUniqueID());
std::tie(ContextIter, Inserted) = Contexts.insert(NewContext);
assert(Inserted && "Failed to insert DeclContext");
(void)Inserted;
} else if (Tag != dwarf::DW_TAG_namespace &&
!(*ContextIter)->setLastSeenDIE(U, DIE)) {
// The context was found, but it is ambiguous with another context
// in the same file. Mark it invalid.
return PointerIntPair<DeclContext *, 1>(*ContextIter, /* IntVal= */ 1);
}
assert(ContextIter != Contexts.end());
// FIXME: dsymutil-classic compatibility. Union types aren't
// uniques, but their children might be.
if ((Tag == dwarf::DW_TAG_subprogram &&
Context.getTag() != dwarf::DW_TAG_structure_type &&
Context.getTag() != dwarf::DW_TAG_class_type) ||
(Tag == dwarf::DW_TAG_union_type))
return PointerIntPair<DeclContext *, 1>(*ContextIter, /* IntVal= */ 1);
return PointerIntPair<DeclContext *, 1>(*ContextIter);
}
StringRef
DeclContextTree::getResolvedPath(CompileUnit &CU, unsigned FileNum,
const DWARFDebugLine::LineTable &LineTable) {
std::pair<unsigned, unsigned> Key = {CU.getUniqueID(), FileNum};
ResolvedPathsMap::const_iterator It = ResolvedPaths.find(Key);
if (It == ResolvedPaths.end()) {
std::string FileName;
bool FoundFileName = LineTable.getFileNameByIndex(
FileNum, CU.getOrigUnit().getCompilationDir(),
DILineInfoSpecifier::FileLineInfoKind::AbsoluteFilePath, FileName);
(void)FoundFileName;
assert(FoundFileName && "Must get file name from line table");
// Second level of caching, this time based on the file's parent
// path.
StringRef ResolvedPath = PathResolver.resolve(FileName, StringPool);
It = ResolvedPaths.insert(std::make_pair(Key, ResolvedPath)).first;
}
return It->second;
}
} // namespace llvm
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