llvm-project/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.h
Michael Buch 57a7907179
[lldb][Expression] Add structor variant to LLDB's function call labels (#149827)
Depends on
* https://github.com/llvm/llvm-project/pull/148877
* https://github.com/llvm/llvm-project/pull/155483
* https://github.com/llvm/llvm-project/pull/155485
* https://github.com/llvm/llvm-project/pull/154137
* https://github.com/llvm/llvm-project/pull/154142

This patch is an implementation of [this
discussion](https://discourse.llvm.org/t/rfc-lldb-handling-abi-tagged-constructors-destructors-in-expression-evaluator/82816/7)
about handling ABI-tagged structors during expression evaluation.

**Motivation**

LLDB encodes the mangled name of a `DW_TAG_subprogram` into `AsmLabel`s
on function and method Clang AST nodes. This means that when calls to
these functions get lowered into IR (when running JITted expressions),
the address resolver can locate the appropriate symbol by mangled name
(and it is guaranteed to find the symbol because we got the mangled name
from debug-info, instead of letting Clang mangle it based on AST
structure). However, we don't do this for
`CXXConstructorDecl`s/`CXXDestructorDecl`s because these structor
declarations in DWARF don't have a linkage name. This is because there
can be multiple variants of a structor, each with a distinct mangling in
the Itanium ABI. Each structor variant has its own definition
`DW_TAG_subprogram`. So LLDB doesn't know which mangled name to put into
the `AsmLabel`.

Currently this means using ABI-tagged structors in LLDB expressions
won't work (see [this
RFC](https://discourse.llvm.org/t/rfc-lldb-handling-abi-tagged-constructors-destructors-in-expression-evaluator/82816)
for concrete examples).

**Proposed Solution**

The `FunctionCallLabel` encoding that we put into `AsmLabel`s already
supports stuffing more info about a DIE into it. So this patch extends
the `FunctionCallLabel` to contain an optional discriminator (a sequence
of bytes) which the `SymbolFileDWARF` plugin interprets as the
constructor/destructor variant of that DIE. So when searching for the
definition DIE, LLDB will include the structor variant in its heuristic
for determining a match.

There's a few subtleties here:
1. At the point at which LLDB first constructs the label, it has no way
of knowing (just by looking at the debug-info declaration), which
structor variant the expression evaluator is supposed to call. That's
something that gets decided when compiling the expression. So we let the
Clang mangler inject the correct structor variant into the `AsmLabel`
during JITing. I adjusted the `AsmLabelAttr` mangling for this in
https://github.com/llvm/llvm-project/pull/155485. An option would've
been to create a new Clang attribute which behaved like an `AsmLabel`
but with these special semantics for LLDB. My main concern there is that
we'd have to adjust all the `AsmLabelAttr` checks around Clang to also
now account for this new attribute.
2. The compiler is free to omit the `C1` variant of a constructor if the
`C2` variant is sufficient. In that case it may alias `C1` to `C2`,
leaving us with only the `C2` `DW_TAG_subprogram` in the object file.
Linux is one of the platforms where this occurs. For those cases I added
a heuristic in `SymbolFileDWARF` where we pick `C2` if we asked for `C1`
but it doesn't exist. This may not always be correct (e.g., if the
compiler decided to drop `C1` for other reasons).
3. In https://github.com/llvm/llvm-project/pull/154142 Clang will emit
`C4`/`D4` variants of ctors/dtors on declarations. When resolving the
`FunctionCallLabel` we will now substitute the actual variant that Clang
told us we need to call into the mangled name. We do this using LLDB's
`ManglingSubstitutor`. That way we find the definition DIE exactly the
same way we do for regular function calls.
4. In cases where declarations and definitions live in separate modules,
the DIE ID encoded in the function call label may not be enough to find
the definition DIE in the encoded module ID. For those cases we fall
back to how LLDB used to work: look up in all images of the target. To
make sure we don't use the unified mangled name for the fallback lookup,
we change the lookup name to whatever mangled name the FunctionCallLabel
resolved to.

rdar://104968288
2025-09-09 09:02:00 +00:00

398 lines
15 KiB
C++

//===-- SymbolFileDWARFDebugMap.h ------------------------------*- C++ -*-===//
//
// 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
//
//===----------------------------------------------------------------------===//
#ifndef LLDB_SOURCE_PLUGINS_SYMBOLFILE_DWARF_SYMBOLFILEDWARFDEBUGMAP_H
#define LLDB_SOURCE_PLUGINS_SYMBOLFILE_DWARF_SYMBOLFILEDWARFDEBUGMAP_H
#include "DIERef.h"
#include "lldb/Symbol/SymbolFile.h"
#include "lldb/Utility/RangeMap.h"
#include "llvm/Support/Chrono.h"
#include <bitset>
#include <map>
#include <optional>
#include <vector>
#include "UniqueDWARFASTType.h"
#include "lldb/Utility/StructuredData.h"
#include "lldb/lldb-private-enumerations.h"
class DWARFASTParserClang;
namespace lldb_private::plugin {
namespace dwarf {
class SymbolFileDWARF;
class DWARFCompileUnit;
class DWARFDebugAranges;
class DWARFDeclContext;
class SymbolFileDWARFDebugMap : public SymbolFileCommon {
/// LLVM RTTI support.
static char ID;
public:
/// LLVM RTTI support.
/// \{
bool isA(const void *ClassID) const override {
return ClassID == &ID || SymbolFileCommon::isA(ClassID);
}
static bool classof(const SymbolFile *obj) { return obj->isA(&ID); }
/// \}
// Static Functions
static void Initialize();
static void Terminate();
static llvm::StringRef GetPluginNameStatic() { return "dwarf-debugmap"; }
static llvm::StringRef GetPluginDescriptionStatic();
static SymbolFile *CreateInstance(lldb::ObjectFileSP objfile_sp);
// Constructors and Destructors
SymbolFileDWARFDebugMap(lldb::ObjectFileSP objfile_sp);
~SymbolFileDWARFDebugMap() override;
uint32_t CalculateAbilities() override;
void InitializeObject() override;
// Compile Unit function calls
lldb::LanguageType ParseLanguage(CompileUnit &comp_unit) override;
XcodeSDK ParseXcodeSDK(CompileUnit &comp_unit) override;
llvm::SmallSet<lldb::LanguageType, 4>
ParseAllLanguages(CompileUnit &comp_unit) override;
size_t ParseFunctions(CompileUnit &comp_unit) override;
bool ParseLineTable(CompileUnit &comp_unit) override;
bool ParseDebugMacros(CompileUnit &comp_unit) override;
bool ForEachExternalModule(CompileUnit &, llvm::DenseSet<SymbolFile *> &,
llvm::function_ref<bool(Module &)>) override;
bool ParseSupportFiles(CompileUnit &comp_unit,
SupportFileList &support_files) override;
bool ParseIsOptimized(CompileUnit &comp_unit) override;
size_t ParseTypes(CompileUnit &comp_unit) override;
bool
ParseImportedModules(const SymbolContext &sc,
std::vector<SourceModule> &imported_modules) override;
size_t ParseBlocksRecursive(Function &func) override;
size_t ParseVariablesForContext(const SymbolContext &sc) override;
Type *ResolveTypeUID(lldb::user_id_t type_uid) override;
std::optional<ArrayInfo>
GetDynamicArrayInfoForUID(lldb::user_id_t type_uid,
const ExecutionContext *exe_ctx) override;
CompilerDeclContext GetDeclContextForUID(lldb::user_id_t uid) override;
CompilerDeclContext GetDeclContextContainingUID(lldb::user_id_t uid) override;
std::vector<CompilerContext>
GetCompilerContextForUID(lldb::user_id_t uid) override;
void ParseDeclsForContext(CompilerDeclContext decl_ctx) override;
bool CompleteType(CompilerType &compiler_type) override;
uint32_t ResolveSymbolContext(const Address &so_addr,
lldb::SymbolContextItem resolve_scope,
SymbolContext &sc) override;
uint32_t ResolveSymbolContext(const SourceLocationSpec &src_location_spec,
lldb::SymbolContextItem resolve_scope,
SymbolContextList &sc_list) override;
Status CalculateFrameVariableError(StackFrame &frame) override;
void FindGlobalVariables(ConstString name,
const CompilerDeclContext &parent_decl_ctx,
uint32_t max_matches,
VariableList &variables) override;
void FindGlobalVariables(const RegularExpression &regex, uint32_t max_matches,
VariableList &variables) override;
void FindFunctions(const Module::LookupInfo &lookup_info,
const CompilerDeclContext &parent_decl_ctx,
bool include_inlines, SymbolContextList &sc_list) override;
void FindFunctions(const RegularExpression &regex, bool include_inlines,
SymbolContextList &sc_list) override;
void FindTypes(const lldb_private::TypeQuery &match,
lldb_private::TypeResults &results) override;
CompilerDeclContext FindNamespace(ConstString name,
const CompilerDeclContext &parent_decl_ctx,
bool only_root_namespaces) override;
void GetTypes(SymbolContextScope *sc_scope, lldb::TypeClass type_mask,
TypeList &type_list) override;
std::vector<std::unique_ptr<CallEdge>>
ParseCallEdgesInFunction(UserID func_id) override;
void DumpClangAST(Stream &s, llvm::StringRef filter) override;
/// List separate oso files.
bool GetSeparateDebugInfo(StructuredData::Dictionary &d, bool errors_only,
bool load_all_debug_info = false) override;
// PluginInterface protocol
llvm::StringRef GetPluginName() override { return GetPluginNameStatic(); }
// Statistics overrides.
ModuleList GetDebugInfoModules() override;
void
GetCompileOptions(std::unordered_map<lldb::CompUnitSP, Args> &args) override;
llvm::Expected<SymbolContext>
ResolveFunctionCallLabel(FunctionCallLabel &label) override;
protected:
enum { kHaveInitializedOSOs = (1 << 0), kNumFlags };
friend class DebugMapModule;
friend class ::DWARFASTParserClang;
friend class DWARFCompileUnit;
friend class SymbolFileDWARF;
struct OSOInfo {
lldb::ModuleSP module_sp;
OSOInfo() : module_sp() {}
};
typedef std::shared_ptr<OSOInfo> OSOInfoSP;
typedef RangeDataVector<lldb::addr_t, lldb::addr_t, lldb::addr_t>
FileRangeMap;
// Class specific types
struct CompileUnitInfo {
FileSpec so_file;
ConstString oso_path;
llvm::sys::TimePoint<> oso_mod_time;
Status oso_load_error;
OSOInfoSP oso_sp;
/// The compile units that an object file contains.
llvm::SmallVector<lldb::CompUnitSP, 2> compile_units_sps;
/// A map from the compile unit ID to its index in the vector.
llvm::SmallDenseMap<uint64_t, uint64_t, 2> id_to_index_map;
uint32_t first_symbol_index = UINT32_MAX;
uint32_t last_symbol_index = UINT32_MAX;
uint32_t first_symbol_id = UINT32_MAX;
uint32_t last_symbol_id = UINT32_MAX;
FileRangeMap file_range_map;
bool file_range_map_valid = false;
CompileUnitInfo() = default;
const FileRangeMap &GetFileRangeMap(SymbolFileDWARFDebugMap *exe_symfile);
};
// Protected Member Functions
void InitOSO();
/// This function actually returns the number of object files, which may be
/// less than the actual number of compile units, since an object file may
/// contain more than one compile unit. SymbolFileDWARFDebugMap looks up the
/// number of compile units by reading the nlist symbol table, which
/// currently, on macOS, only reports one compile unit per object file, and
/// there's no efficient way to calculate the actual number of compile units
/// upfront.
uint32_t CalculateNumCompileUnits() override;
/// This function actually returns the first compile unit the object file at
/// the given index contains.
lldb::CompUnitSP ParseCompileUnitAtIndex(uint32_t index) override;
static uint32_t GetOSOIndexFromUserID(lldb::user_id_t uid) {
std::optional<uint32_t> OsoNum = DIERef(uid).file_index();
lldbassert(OsoNum && "Invalid OSO Index");
return *OsoNum;
}
static SymbolFileDWARF *GetSymbolFileAsSymbolFileDWARF(SymbolFile *sym_file);
bool GetFileSpecForSO(uint32_t oso_idx, FileSpec &file_spec);
CompileUnitInfo *GetCompUnitInfo(const SymbolContext &sc);
CompileUnitInfo *GetCompUnitInfo(const CompileUnit &comp_unit);
size_t GetCompUnitInfosForModule(const Module *oso_module,
std::vector<CompileUnitInfo *> &cu_infos);
Module *GetModuleByCompUnitInfo(CompileUnitInfo *comp_unit_info);
Module *GetModuleByOSOIndex(uint32_t oso_idx);
ObjectFile *GetObjectFileByCompUnitInfo(CompileUnitInfo *comp_unit_info);
ObjectFile *GetObjectFileByOSOIndex(uint32_t oso_idx);
uint32_t GetCompUnitInfoIndex(const CompileUnitInfo *comp_unit_info);
SymbolFileDWARF *GetSymbolFile(const SymbolContext &sc);
SymbolFileDWARF *GetSymbolFile(const CompileUnit &comp_unit);
SymbolFileDWARF *GetSymbolFileByCompUnitInfo(CompileUnitInfo *comp_unit_info);
SymbolFileDWARF *GetSymbolFileByOSOIndex(uint32_t oso_idx);
/// If closure returns \ref IterationAction::Continue, iteration
/// continues. Otherwise, iteration terminates.
void
ForEachSymbolFile(std::string description,
std::function<IterationAction(SymbolFileDWARF &)> closure);
CompileUnitInfo *GetCompileUnitInfoForSymbolWithIndex(uint32_t symbol_idx,
uint32_t *oso_idx_ptr);
CompileUnitInfo *GetCompileUnitInfoForSymbolWithID(lldb::user_id_t symbol_id,
uint32_t *oso_idx_ptr);
static int
SymbolContainsSymbolWithIndex(uint32_t *symbol_idx_ptr,
const CompileUnitInfo *comp_unit_info);
static int SymbolContainsSymbolWithID(lldb::user_id_t *symbol_idx_ptr,
const CompileUnitInfo *comp_unit_info);
void
PrivateFindGlobalVariables(ConstString name,
const CompilerDeclContext &parent_decl_ctx,
const std::vector<uint32_t> &name_symbol_indexes,
uint32_t max_matches, VariableList &variables);
void SetCompileUnit(SymbolFileDWARF *oso_dwarf,
const lldb::CompUnitSP &cu_sp);
/// Returns the compile unit associated with the dwarf compile unit. This may
/// be one of the extra compile units an object file contains which isn't
/// reachable by ParseCompileUnitAtIndex(uint32_t).
lldb::CompUnitSP GetCompileUnit(SymbolFileDWARF *oso_dwarf,
DWARFCompileUnit &dwarf_cu);
CompileUnitInfo *GetCompileUnitInfo(SymbolFileDWARF *oso_dwarf);
DWARFDIE FindDefinitionDIE(const DWARFDIE &die);
lldb::TypeSP FindCompleteObjCDefinitionTypeForDIE(
const DWARFDIE &die, ConstString type_name, bool must_be_implementation);
llvm::DenseMap<lldb::opaque_compiler_type_t, DIERef> &
GetForwardDeclCompilerTypeToDIE() {
return m_forward_decl_compiler_type_to_die;
}
UniqueDWARFASTTypeMap &GetUniqueDWARFASTTypeMap() {
return m_unique_ast_type_map;
}
llvm::DenseMap<const DWARFDebugInfoEntry *, Type *> &GetDIEToType() {
return m_die_to_type;
}
// OSOEntry
class OSOEntry {
public:
OSOEntry() = default;
OSOEntry(uint32_t exe_sym_idx, lldb::addr_t oso_file_addr)
: m_exe_sym_idx(exe_sym_idx), m_oso_file_addr(oso_file_addr) {}
uint32_t GetExeSymbolIndex() const { return m_exe_sym_idx; }
bool operator<(const OSOEntry &rhs) const {
return m_exe_sym_idx < rhs.m_exe_sym_idx;
}
lldb::addr_t GetOSOFileAddress() const { return m_oso_file_addr; }
void SetOSOFileAddress(lldb::addr_t oso_file_addr) {
m_oso_file_addr = oso_file_addr;
}
protected:
uint32_t m_exe_sym_idx = UINT32_MAX;
lldb::addr_t m_oso_file_addr = LLDB_INVALID_ADDRESS;
};
typedef RangeDataVector<lldb::addr_t, lldb::addr_t, OSOEntry> DebugMap;
// Member Variables
std::bitset<kNumFlags> m_flags;
std::vector<CompileUnitInfo> m_compile_unit_infos;
std::vector<uint32_t> m_func_indexes; // Sorted by address
std::vector<uint32_t> m_glob_indexes;
std::map<std::pair<ConstString, llvm::sys::TimePoint<>>, OSOInfoSP> m_oso_map;
// A map from CompilerType to the struct/class/union/enum DIE (might be a
// declaration or a definition) that is used to construct it.
llvm::DenseMap<lldb::opaque_compiler_type_t, DIERef>
m_forward_decl_compiler_type_to_die;
UniqueDWARFASTTypeMap m_unique_ast_type_map;
llvm::DenseMap<const DWARFDebugInfoEntry *, Type *> m_die_to_type;
DebugMap m_debug_map;
// When an object file from the debug map gets parsed in
// SymbolFileDWARF, it needs to tell the debug map about the object
// files addresses by calling this function once for each N_FUN,
// N_GSYM and N_STSYM and after all entries in the debug map have
// been matched up, FinalizeOSOFileRanges() should be called.
bool AddOSOFileRange(CompileUnitInfo *cu_info, lldb::addr_t exe_file_addr,
lldb::addr_t exe_byte_size, lldb::addr_t oso_file_addr,
lldb::addr_t oso_byte_size);
// Called after calling AddOSOFileRange() for each object file debug
// map entry to finalize the info for the unlinked compile unit.
void FinalizeOSOFileRanges(CompileUnitInfo *cu_info);
/// Convert \a addr from a .o file address, to an executable address.
///
/// \param[in] addr
/// A section offset address from a .o file
///
/// \return
/// Returns true if \a addr was converted to be an executable
/// section/offset address, false otherwise.
bool LinkOSOAddress(Address &addr);
/// Convert a .o file "file address" to an executable "file address".
///
/// \param[in] oso_symfile
/// The DWARF symbol file that contains \a oso_file_addr
///
/// \param[in] oso_file_addr
/// A .o file "file address" to convert.
///
/// \return
/// LLDB_INVALID_ADDRESS if \a oso_file_addr is not in the
/// linked executable, otherwise a valid "file address" from the
/// linked executable that contains the debug map.
lldb::addr_t LinkOSOFileAddress(SymbolFileDWARF *oso_symfile,
lldb::addr_t oso_file_addr);
/// Given a line table full of lines with "file addresses" that are
/// for a .o file represented by \a oso_symfile, link a new line table
/// and return it.
///
/// \param[in] oso_symfile
/// The DWARF symbol file that produced the \a line_table
///
/// \param[in] line_table
/// A pointer to the line table.
///
/// \return
/// Returns a valid line table full of linked addresses, or NULL
/// if none of the line table addresses exist in the main
/// executable.
LineTable *LinkOSOLineTable(SymbolFileDWARF *oso_symfile,
LineTable *line_table);
size_t AddOSOARanges(SymbolFileDWARF *dwarf2Data,
DWARFDebugAranges *debug_aranges);
};
} // namespace dwarf
} // namespace lldb_private::plugin
#endif // LLDB_SOURCE_PLUGINS_SYMBOLFILE_DWARF_SYMBOLFILEDWARFDEBUGMAP_H