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//===- tools/dsymutil/DeclContext.h - Dwarf debug info linker ---*- C++ -*-===//
// The LLVM Compiler Infrastructure
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
#include "CompileUnit.h"
#include "NonRelocatableStringpool.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DenseMapInfo.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/DebugInfo/DWARF/DWARFDie.h"
#include "llvm/Support/Path.h"
namespace llvm {
namespace dsymutil {
struct DeclMapInfo;
/// Small helper that resolves and caches file paths. This helps reduce the
/// number of calls to realpath which is expensive. We assume the input are
/// files, and cache the realpath of their parent. This way we can quickly
/// resolve different files under the same path.
class CachedPathResolver {
/// Resolve a path by calling realpath and cache its result. The returned
/// StringRef is interned in the given \p StringPool.
StringRef resolve(std::string Path, NonRelocatableStringpool &StringPool) {
StringRef FileName = sys::path::filename(Path);
SmallString<256> ParentPath = sys::path::parent_path(Path);
// If the ParentPath has not yet been resolved, resolve and cache it for
// future look-ups.
if (!ResolvedPaths.count(ParentPath)) {
SmallString<256> RealPath;
sys::fs::real_path(ParentPath, RealPath);
ResolvedPaths.insert({ParentPath, StringRef(RealPath).str()});
// Join the file name again with the resolved path.
SmallString<256> ResolvedPath(ResolvedPaths[ParentPath]);
sys::path::append(ResolvedPath, FileName);
return StringPool.internString(ResolvedPath);
StringMap<std::string> ResolvedPaths;
/// A DeclContext is a named program scope that is used for ODR uniquing of
/// types.
/// The set of DeclContext for the ODR-subject parts of a Dwarf link is
/// expanded (and uniqued) with each new object file processed. We need to
/// determine the context of each DIE in an linked object file to see if the
/// corresponding type has already been emitted.
/// The contexts are conceptually organized as a tree (eg. a function scope is
/// contained in a namespace scope that contains other scopes), but
/// storing/accessing them in an actual tree is too inefficient: we need to be
/// able to very quickly query a context for a given child context by name.
/// Storing a StringMap in each DeclContext would be too space inefficient.
/// The solution here is to give each DeclContext a link to its parent (this
/// allows to walk up the tree), but to query the existence of a specific
/// DeclContext using a separate DenseMap keyed on the hash of the fully
/// qualified name of the context.
class DeclContext {
using Map = DenseSet<DeclContext *, DeclMapInfo>;
DeclContext() : DefinedInClangModule(0), Parent(*this) {}
DeclContext(unsigned Hash, uint32_t Line, uint32_t ByteSize, uint16_t Tag,
StringRef Name, StringRef File, const DeclContext &Parent,
DWARFDie LastSeenDIE = DWARFDie(), unsigned CUId = 0)
: QualifiedNameHash(Hash), Line(Line), ByteSize(ByteSize), Tag(Tag),
DefinedInClangModule(0), Name(Name), File(File), Parent(Parent),
LastSeenDIE(LastSeenDIE), LastSeenCompileUnitID(CUId) {}
uint32_t getQualifiedNameHash() const { return QualifiedNameHash; }
bool setLastSeenDIE(CompileUnit &U, const DWARFDie &Die);
uint32_t getCanonicalDIEOffset() const { return CanonicalDIEOffset; }
void setCanonicalDIEOffset(uint32_t Offset) { CanonicalDIEOffset = Offset; }
bool isDefinedInClangModule() const { return DefinedInClangModule; }
void setDefinedInClangModule(bool Val) { DefinedInClangModule = Val; }
uint16_t getTag() const { return Tag; }
StringRef getName() const { return Name; }
friend DeclMapInfo;
unsigned QualifiedNameHash = 0;
uint32_t Line = 0;
uint32_t ByteSize = 0;
uint16_t Tag = dwarf::DW_TAG_compile_unit;
unsigned DefinedInClangModule : 1;
StringRef Name;
StringRef File;
const DeclContext &Parent;
uint32_t LastSeenCompileUnitID = 0;
uint32_t CanonicalDIEOffset = 0;
/// This class gives a tree-like API to the DenseMap that stores the
/// DeclContext objects. It holds the BumpPtrAllocator where these objects will
/// be allocated.
class DeclContextTree {
/// Get the child of \a Context described by \a DIE in \a Unit. The
/// required strings will be interned in \a StringPool.
/// \returns The child DeclContext along with one bit that is set if
/// this context is invalid.
/// An invalid context means it shouldn't be considered for uniquing, but its
/// not returning null, because some children of that context might be
/// uniquing candidates.
/// FIXME: The invalid bit along the return value is to emulate some
/// dsymutil-classic functionality.
PointerIntPair<DeclContext *, 1>
getChildDeclContext(DeclContext &Context, const DWARFDie &DIE,
CompileUnit &Unit, UniquingStringPool &StringPool,
bool InClangModule);
DeclContext &getRoot() { return Root; }
BumpPtrAllocator Allocator;
DeclContext Root;
DeclContext::Map Contexts;
/// Cache resolved paths from the line table.
CachedPathResolver PathResolver;
/// Info type for the DenseMap storing the DeclContext pointers.
struct DeclMapInfo : private DenseMapInfo<DeclContext *> {
using DenseMapInfo<DeclContext *>::getEmptyKey;
using DenseMapInfo<DeclContext *>::getTombstoneKey;
static unsigned getHashValue(const DeclContext *Ctxt) {
return Ctxt->QualifiedNameHash;
static bool isEqual(const DeclContext *LHS, const DeclContext *RHS) {
if (RHS == getEmptyKey() || RHS == getTombstoneKey())
return RHS == LHS;
return LHS->QualifiedNameHash == RHS->QualifiedNameHash &&
LHS->Line == RHS->Line && LHS->ByteSize == RHS->ByteSize &&
LHS-> == RHS-> &&
LHS-> == RHS-> &&
LHS->Parent.QualifiedNameHash == RHS->Parent.QualifiedNameHash;
} // end namespace dsymutil
} // end namespace llvm