cf3524a574
Introduce a new object and symbol file format with the goal of mapping
addresses to symbol names. I'd like to think of is as an extremely
simple textual symtab. The file format consists of a triple, a UUID and
a list of symbols. JSON is used for the encoding, but that's mostly an
implementation detail. The goal of the format was to be simple and human
readable.
The new file format is motivated by two use cases:
- Stripped binaries: when a binary is stripped, you lose the ability to
do thing like setting symbolic breakpoints. You can keep the
unstripped binary around, but if all you need is the stripped
symbols then that's a lot of overhead. Instead, we could save the
stripped symbols to a file and load them in the debugger when
needed. I want to extend llvm-strip to have a mode where it emits
this new file format.
- Interactive crashlogs: with interactive crashlogs, if we don't have
the binary or the dSYM for a particular module, we currently show an
unnamed symbol for those frames. This is a regression compared to the
textual format, that has these frames pre-symbolicated. Given that
this information is available in the JSON crashlog, we need a way to
tell LLDB about it. With the new symbol file format, we can easily
synthesize a symbol file for each of those modules and load them to
symbolicate those frames.
Here's an example of the file format:
{
"triple": "arm64-apple-macosx13.0.0",
"uuid": "36D0CCE7-8ED2-3CA3-96B0-48C1764DA908",
"symbols": [
{
"name": "main",
"type": "code",
"size": 32,
"address": 4294983568
},
{
"name": "foo",
"type": "code",
"size": 8,
"address": 4294983560
}
]
}
Differential revision: https://reviews.llvm.org/D145180
106 lines
3.1 KiB
C++
106 lines
3.1 KiB
C++
//===-- SymbolFileJSON.cpp ----------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "SymbolFileJSON.h"
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#include "Plugins/ObjectFile/JSON/ObjectFileJSON.h"
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#include "lldb/Core/Module.h"
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#include "lldb/Core/PluginManager.h"
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#include "lldb/Symbol/CompileUnit.h"
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#include "lldb/Symbol/Function.h"
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#include "lldb/Symbol/ObjectFile.h"
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#include "lldb/Symbol/Symbol.h"
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#include "lldb/Symbol/SymbolContext.h"
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#include "lldb/Symbol/Symtab.h"
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#include "lldb/Symbol/TypeList.h"
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#include "lldb/Utility/LLDBLog.h"
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#include "lldb/Utility/Log.h"
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#include "lldb/Utility/RegularExpression.h"
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#include "lldb/Utility/Timer.h"
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#include "llvm/Support/MemoryBuffer.h"
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#include <memory>
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#include <optional>
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using namespace llvm;
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using namespace lldb;
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using namespace lldb_private;
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LLDB_PLUGIN_DEFINE(SymbolFileJSON)
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char SymbolFileJSON::ID;
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SymbolFileJSON::SymbolFileJSON(lldb::ObjectFileSP objfile_sp)
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: SymbolFileCommon(std::move(objfile_sp)) {}
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void SymbolFileJSON::Initialize() {
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PluginManager::RegisterPlugin(GetPluginNameStatic(),
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GetPluginDescriptionStatic(), CreateInstance);
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}
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void SymbolFileJSON::Terminate() {
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PluginManager::UnregisterPlugin(CreateInstance);
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}
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llvm::StringRef SymbolFileJSON::GetPluginDescriptionStatic() {
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return "Reads debug symbols from a textual symbol table.";
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}
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SymbolFile *SymbolFileJSON::CreateInstance(ObjectFileSP objfile_sp) {
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return new SymbolFileJSON(std::move(objfile_sp));
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}
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uint32_t SymbolFileJSON::CalculateAbilities() {
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if (!m_objfile_sp || !llvm::isa<ObjectFileJSON>(*m_objfile_sp))
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return 0;
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return GlobalVariables | Functions;
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}
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uint32_t SymbolFileJSON::ResolveSymbolContext(const Address &so_addr,
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SymbolContextItem resolve_scope,
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SymbolContext &sc) {
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std::lock_guard<std::recursive_mutex> guard(GetModuleMutex());
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if (m_objfile_sp->GetSymtab() == nullptr)
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return 0;
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uint32_t resolved_flags = 0;
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if (resolve_scope & eSymbolContextSymbol) {
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sc.symbol = m_objfile_sp->GetSymtab()->FindSymbolContainingFileAddress(
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so_addr.GetFileAddress());
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if (sc.symbol)
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resolved_flags |= eSymbolContextSymbol;
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}
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return resolved_flags;
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}
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CompUnitSP SymbolFileJSON::ParseCompileUnitAtIndex(uint32_t idx) { return {}; }
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void SymbolFileJSON::GetTypes(SymbolContextScope *sc_scope, TypeClass type_mask,
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lldb_private::TypeList &type_list) {}
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void SymbolFileJSON::AddSymbols(Symtab &symtab) {
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if (!m_objfile_sp)
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return;
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Symtab *json_symtab = m_objfile_sp->GetSymtab();
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if (!json_symtab)
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return;
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if (&symtab == json_symtab)
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return;
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// Merge the two symbol tables.
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const size_t num_new_symbols = json_symtab->GetNumSymbols();
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for (size_t i = 0; i < num_new_symbols; ++i) {
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Symbol *s = json_symtab->SymbolAtIndex(i);
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symtab.AddSymbol(*s);
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}
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symtab.Finalize();
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}
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