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[lldb][gnustep] Add minimal GNUstepObjCRuntime plugin for LanguageTypeObjC on non-Apple platforms
This is the next patch after D146058. We can now parse expressions to print instance variables from ObjC classes. Until now the expression parser would bail out with an error like this: ``` error: expression failed to parse: error: Error [IRForTarget]: Couldn't find Objective-C indirect ivar symbol OBJC_IVAR_$_TestObj._int ``` Reviewed By: aprantl Differential Revision: https://reviews.llvm.org/D146154
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8 files changed

+417
-12
lines changed

8 files changed

+417
-12
lines changed

‎lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp

Lines changed: 10 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -587,12 +587,19 @@ ClangExpressionParser::ClangExpressionParser(
587587

588588
if (process_sp && lang_opts.ObjC) {
589589
if (auto *runtime = ObjCLanguageRuntime::Get(*process_sp)) {
590-
if (runtime->GetRuntimeVersion() ==
591-
ObjCLanguageRuntime::ObjCRuntimeVersions::eAppleObjC_V2)
590+
switch (runtime->GetRuntimeVersion()) {
591+
case ObjCLanguageRuntime::ObjCRuntimeVersions::eAppleObjC_V2:
592592
lang_opts.ObjCRuntime.set(ObjCRuntime::MacOSX, VersionTuple(10, 7));
593-
else
593+
break;
594+
case ObjCLanguageRuntime::ObjCRuntimeVersions::eObjC_VersionUnknown:
595+
case ObjCLanguageRuntime::ObjCRuntimeVersions::eAppleObjC_V1:
594596
lang_opts.ObjCRuntime.set(ObjCRuntime::FragileMacOSX,
595597
VersionTuple(10, 7));
598+
break;
599+
case ObjCLanguageRuntime::ObjCRuntimeVersions::eGNUstep_libobjc2:
600+
lang_opts.ObjCRuntime.set(ObjCRuntime::GNUstep, VersionTuple(2, 0));
601+
break;
602+
}
596603

597604
if (runtime->HasNewLiteralsAndIndexing())
598605
lang_opts.DebuggerObjCLiteral = true;

‎lldb/source/Plugins/LanguageRuntime/ObjC/CMakeLists.txt

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -7,4 +7,6 @@ add_lldb_library(lldbPluginObjCRuntime
77
lldbTarget
88
lldbUtility
99
)
10+
1011
add_subdirectory(AppleObjCRuntime)
12+
add_subdirectory(GNUstepObjCRuntime)

‎lldb/source/Plugins/LanguageRuntime/ObjC/GNUstepObjCRuntime/CMakeLists.txt

Lines changed: 19 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,19 @@
1+
add_lldb_library(lldbPluginGNUstepObjCRuntime PLUGIN
2+
GNUstepObjCRuntime.cpp
3+
4+
LINK_LIBS
5+
lldbBreakpoint
6+
lldbCore
7+
lldbExpression
8+
lldbHost
9+
lldbInterpreter
10+
lldbSymbol
11+
lldbTarget
12+
lldbUtility
13+
lldbPluginExpressionParserClang
14+
lldbPluginTypeSystemClang
15+
CLANG_LIBS
16+
clangAST
17+
LINK_COMPONENTS
18+
Support
19+
)

‎lldb/source/Plugins/LanguageRuntime/ObjC/GNUstepObjCRuntime/GNUstepObjCRuntime.cpp

Lines changed: 204 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,204 @@
1+
//===-- GNUstepObjCRuntime.cpp --------------------------------------------===//
2+
//
3+
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4+
// See https://llvm.org/LICENSE.txt for license information.
5+
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6+
//
7+
//===----------------------------------------------------------------------===//
8+
9+
#include "GNUstepObjCRuntime.h"
10+
11+
#include "Plugins/TypeSystem/Clang/TypeSystemClang.h"
12+
13+
#include "lldb/Core/Module.h"
14+
#include "lldb/Core/PluginManager.h"
15+
#include "lldb/Core/ValueObject.h"
16+
#include "lldb/Expression/UtilityFunction.h"
17+
#include "lldb/Target/ExecutionContext.h"
18+
#include "lldb/Target/Process.h"
19+
#include "lldb/Target/Target.h"
20+
#include "lldb/Utility/ArchSpec.h"
21+
#include "lldb/Utility/ConstString.h"
22+
23+
using namespace lldb;
24+
using namespace lldb_private;
25+
26+
LLDB_PLUGIN_DEFINE(GNUstepObjCRuntime)
27+
28+
char GNUstepObjCRuntime::ID = 0;
29+
30+
void GNUstepObjCRuntime::Initialize() {
31+
PluginManager::RegisterPlugin(
32+
GetPluginNameStatic(), "GNUstep Objective-C Language Runtime - libobjc2",
33+
CreateInstance);
34+
}
35+
36+
void GNUstepObjCRuntime::Terminate() {
37+
PluginManager::UnregisterPlugin(CreateInstance);
38+
}
39+
40+
LanguageRuntime *GNUstepObjCRuntime::CreateInstance(Process *process,
41+
LanguageType language) {
42+
if (language != eLanguageTypeObjC)
43+
return nullptr;
44+
if (!process)
45+
return nullptr;
46+
47+
Target &target = process->GetTarget();
48+
const llvm::Triple &TT = target.GetArchitecture().GetTriple();
49+
if (TT.getVendor() == llvm::Triple::VendorType::Apple)
50+
return nullptr;
51+
52+
const ModuleList &images = target.GetImages();
53+
if (TT.isOSBinFormatELF()) {
54+
SymbolContextList eh_pers;
55+
RegularExpression regex("__gnustep_objc[x]*_personality_v[0-9]+");
56+
images.FindSymbolsMatchingRegExAndType(regex, eSymbolTypeCode, eh_pers);
57+
if (eh_pers.GetSize() == 0)
58+
return nullptr;
59+
} else if (TT.isOSWindows()) {
60+
SymbolContextList objc_mandatory;
61+
images.FindSymbolsWithNameAndType(ConstString("__objc_load"),
62+
eSymbolTypeCode, objc_mandatory);
63+
if (objc_mandatory.GetSize() == 0)
64+
return nullptr;
65+
}
66+
67+
return new GNUstepObjCRuntime(process);
68+
}
69+
70+
GNUstepObjCRuntime::~GNUstepObjCRuntime() = default;
71+
72+
GNUstepObjCRuntime::GNUstepObjCRuntime(Process *process)
73+
: ObjCLanguageRuntime(process), m_objc_module_sp(nullptr) {
74+
ReadObjCLibraryIfNeeded(process->GetTarget().GetImages());
75+
}
76+
77+
bool GNUstepObjCRuntime::GetObjectDescription(Stream &str,
78+
ValueObject &valobj) {
79+
// TODO: ObjC has a generic way to do this
80+
return false;
81+
}
82+
bool GNUstepObjCRuntime::GetObjectDescription(
83+
Stream &strm, Value &value, ExecutionContextScope *exe_scope) {
84+
// TODO: ObjC has a generic way to do this
85+
return false;
86+
}
87+
88+
bool GNUstepObjCRuntime::CouldHaveDynamicValue(ValueObject &in_value) {
89+
static constexpr bool check_cxx = false;
90+
static constexpr bool check_objc = true;
91+
return in_value.GetCompilerType().IsPossibleDynamicType(nullptr, check_cxx,
92+
check_objc);
93+
}
94+
95+
bool GNUstepObjCRuntime::GetDynamicTypeAndAddress(
96+
ValueObject &in_value, DynamicValueType use_dynamic,
97+
TypeAndOrName &class_type_or_name, Address &address,
98+
Value::ValueType &value_type) {
99+
return false;
100+
}
101+
102+
TypeAndOrName
103+
GNUstepObjCRuntime::FixUpDynamicType(const TypeAndOrName &type_and_or_name,
104+
ValueObject &static_value) {
105+
CompilerType static_type(static_value.GetCompilerType());
106+
Flags static_type_flags(static_type.GetTypeInfo());
107+
108+
TypeAndOrName ret(type_and_or_name);
109+
if (type_and_or_name.HasType()) {
110+
// The type will always be the type of the dynamic object. If our parent's
111+
// type was a pointer, then our type should be a pointer to the type of the
112+
// dynamic object. If a reference, then the original type should be
113+
// okay...
114+
CompilerType orig_type = type_and_or_name.GetCompilerType();
115+
CompilerType corrected_type = orig_type;
116+
if (static_type_flags.AllSet(eTypeIsPointer))
117+
corrected_type = orig_type.GetPointerType();
118+
ret.SetCompilerType(corrected_type);
119+
} else {
120+
// If we are here we need to adjust our dynamic type name to include the
121+
// correct & or * symbol
122+
std::string corrected_name(type_and_or_name.GetName().GetCString());
123+
if (static_type_flags.AllSet(eTypeIsPointer))
124+
corrected_name.append(" *");
125+
// the parent type should be a correctly pointer'ed or referenc'ed type
126+
ret.SetCompilerType(static_type);
127+
ret.SetName(corrected_name.c_str());
128+
}
129+
return ret;
130+
}
131+
132+
BreakpointResolverSP
133+
GNUstepObjCRuntime::CreateExceptionResolver(const BreakpointSP &bkpt,
134+
bool catch_bp, bool throw_bp) {
135+
BreakpointResolverSP resolver_sp;
136+
137+
if (throw_bp)
138+
resolver_sp = std::make_shared<BreakpointResolverName>(
139+
bkpt, "objc_exception_throw", eFunctionNameTypeBase,
140+
eLanguageTypeUnknown, Breakpoint::Exact, 0, eLazyBoolNo);
141+
142+
return resolver_sp;
143+
}
144+
145+
llvm::Expected<std::unique_ptr<UtilityFunction>>
146+
GNUstepObjCRuntime::CreateObjectChecker(std::string name,
147+
ExecutionContext &exe_ctx) {
148+
// TODO: This function is supposed to check whether an ObjC selector is
149+
// present for an object. Might be implemented similar as in the Apple V2
150+
// runtime.
151+
const char *function_template = R"(
152+
extern "C" void
153+
%s(void *$__lldb_arg_obj, void *$__lldb_arg_selector) {}
154+
)";
155+
156+
char empty_function_code[2048];
157+
int len = ::snprintf(empty_function_code, sizeof(empty_function_code),
158+
function_template, name.c_str());
159+
160+
assert(len < (int)sizeof(empty_function_code));
161+
UNUSED_IF_ASSERT_DISABLED(len);
162+
163+
return GetTargetRef().CreateUtilityFunction(empty_function_code, name,
164+
eLanguageTypeC, exe_ctx);
165+
}
166+
167+
ThreadPlanSP
168+
GNUstepObjCRuntime::GetStepThroughTrampolinePlan(Thread &thread,
169+
bool stop_others) {
170+
// TODO: Implement this properly to avoid stepping into things like PLT stubs
171+
return nullptr;
172+
}
173+
174+
void GNUstepObjCRuntime::UpdateISAToDescriptorMapIfNeeded() {
175+
// TODO: Support lazily named and dynamically loaded Objective-C classes
176+
}
177+
178+
bool GNUstepObjCRuntime::IsModuleObjCLibrary(const ModuleSP &module_sp) {
179+
if (!module_sp)
180+
return false;
181+
const FileSpec &module_file_spec = module_sp->GetFileSpec();
182+
if (!module_file_spec)
183+
return false;
184+
llvm::StringRef filename = module_file_spec.GetFilename().GetStringRef();
185+
const llvm::Triple &TT = GetTargetRef().GetArchitecture().GetTriple();
186+
if (TT.isOSBinFormatELF())
187+
return filename.starts_with("libobjc.so");
188+
if (TT.isOSWindows())
189+
return filename == "objc.dll";
190+
return false;
191+
}
192+
193+
bool GNUstepObjCRuntime::ReadObjCLibrary(const ModuleSP &module_sp) {
194+
assert(m_objc_module_sp == nullptr && "Check HasReadObjCLibrary() first");
195+
m_objc_module_sp = module_sp;
196+
197+
// Right now we don't use this, but we might want to check for debugger
198+
// runtime support symbols like 'gdb_object_getClass' in the future.
199+
return true;
200+
}
201+
202+
void GNUstepObjCRuntime::ModulesDidLoad(const ModuleList &module_list) {
203+
ReadObjCLibraryIfNeeded(module_list);
204+
}

‎lldb/source/Plugins/LanguageRuntime/ObjC/GNUstepObjCRuntime/GNUstepObjCRuntime.h

Lines changed: 111 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,111 @@
1+
//===-- GNUstepObjCRuntime.h ------------------------------------*- C++ -*-===//
2+
//
3+
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4+
// See https://llvm.org/LICENSE.txt for license information.
5+
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6+
//
7+
//===----------------------------------------------------------------------===//
8+
9+
#ifndef LLDB_SOURCE_PLUGINS_LANGUAGERUNTIME_OBJC_GNUSTEPOBJCRUNTIME_GNUSTEPOBJCRUNTIME_H
10+
#define LLDB_SOURCE_PLUGINS_LANGUAGERUNTIME_OBJC_GNUSTEPOBJCRUNTIME_GNUSTEPOBJCRUNTIME_H
11+
12+
#include "lldb/Target/LanguageRuntime.h"
13+
#include "lldb/lldb-private.h"
14+
15+
#include "Plugins/LanguageRuntime/ObjC/ObjCLanguageRuntime.h"
16+
17+
#include "llvm/ADT/StringRef.h"
18+
#include "llvm/Support/Error.h"
19+
20+
#include <optional>
21+
22+
namespace lldb_private {
23+
24+
class GNUstepObjCRuntime : public lldb_private::ObjCLanguageRuntime {
25+
public:
26+
~GNUstepObjCRuntime() override;
27+
28+
//
29+
// PluginManager, PluginInterface and LLVM RTTI implementation
30+
//
31+
32+
static char ID;
33+
34+
static void Initialize();
35+
36+
static void Terminate();
37+
38+
static lldb_private::LanguageRuntime *
39+
CreateInstance(Process *process, lldb::LanguageType language);
40+
41+
static llvm::StringRef GetPluginNameStatic() {
42+
return "gnustep-objc-libobjc2";
43+
}
44+
45+
llvm::StringRef GetPluginName() override { return GetPluginNameStatic(); }
46+
47+
void ModulesDidLoad(const ModuleList &module_list) override;
48+
49+
bool isA(const void *ClassID) const override {
50+
return ClassID == &ID || ObjCLanguageRuntime::isA(ClassID);
51+
}
52+
53+
static bool classof(const LanguageRuntime *runtime) {
54+
return runtime->isA(&ID);
55+
}
56+
57+
//
58+
// LanguageRuntime implementation
59+
//
60+
bool GetObjectDescription(Stream &str, Value &value,
61+
ExecutionContextScope *exe_scope) override;
62+
63+
bool GetObjectDescription(Stream &str, ValueObject &object) override;
64+
65+
bool CouldHaveDynamicValue(ValueObject &in_value) override;
66+
67+
bool GetDynamicTypeAndAddress(ValueObject &in_value,
68+
lldb::DynamicValueType use_dynamic,
69+
TypeAndOrName &class_type_or_name,
70+
Address &address,
71+
Value::ValueType &value_type) override;
72+
73+
TypeAndOrName FixUpDynamicType(const TypeAndOrName &type_and_or_name,
74+
ValueObject &static_value) override;
75+
76+
lldb::BreakpointResolverSP
77+
CreateExceptionResolver(const lldb::BreakpointSP &bkpt, bool catch_bp,
78+
bool throw_bp) override;
79+
80+
lldb::ThreadPlanSP GetStepThroughTrampolinePlan(Thread &thread,
81+
bool stop_others) override;
82+
83+
//
84+
// ObjCLanguageRuntime implementation
85+
//
86+
87+
bool IsModuleObjCLibrary(const lldb::ModuleSP &module_sp) override;
88+
89+
bool ReadObjCLibrary(const lldb::ModuleSP &module_sp) override;
90+
91+
bool HasReadObjCLibrary() override { return m_objc_module_sp != nullptr; }
92+
93+
llvm::Expected<std::unique_ptr<UtilityFunction>>
94+
CreateObjectChecker(std::string name, ExecutionContext &exe_ctx) override;
95+
96+
ObjCRuntimeVersions GetRuntimeVersion() const override {
97+
return ObjCRuntimeVersions::eGNUstep_libobjc2;
98+
}
99+
100+
void UpdateISAToDescriptorMapIfNeeded() override;
101+
102+
protected:
103+
// Call CreateInstance instead.
104+
GNUstepObjCRuntime(Process *process);
105+
106+
lldb::ModuleSP m_objc_module_sp;
107+
};
108+
109+
} // namespace lldb_private
110+
111+
#endif // LLDB_SOURCE_PLUGINS_LANGUAGERUNTIME_OBJC_GNUSTEPOBJCRUNTIME_GNUSTEPOBJCRUNTIME_H

‎lldb/source/Plugins/LanguageRuntime/ObjC/ObjCLanguageRuntime.cpp

Lines changed: 16 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -235,6 +235,22 @@ ObjCLanguageRuntime::GetDescriptorIteratorPair(bool update_if_needed) {
235235
m_isa_to_descriptor.begin(), m_isa_to_descriptor.end());
236236
}
237237

238+
void ObjCLanguageRuntime::ReadObjCLibraryIfNeeded(
239+
const ModuleList &module_list) {
240+
if (!HasReadObjCLibrary()) {
241+
std::lock_guard<std::recursive_mutex> guard(module_list.GetMutex());
242+
243+
size_t num_modules = module_list.GetSize();
244+
for (size_t i = 0; i < num_modules; i++) {
245+
auto mod = module_list.GetModuleAtIndex(i);
246+
if (IsModuleObjCLibrary(mod)) {
247+
ReadObjCLibrary(mod);
248+
break;
249+
}
250+
}
251+
}
252+
}
253+
238254
ObjCLanguageRuntime::ObjCISA
239255
ObjCLanguageRuntime::GetParentClass(ObjCLanguageRuntime::ObjCISA isa) {
240256
ClassDescriptorSP objc_class_sp(GetClassDescriptorFromISA(isa));

‎lldb/source/Plugins/LanguageRuntime/ObjC/ObjCLanguageRuntime.h

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -38,7 +38,8 @@ class ObjCLanguageRuntime : public LanguageRuntime {
3838
enum class ObjCRuntimeVersions {
3939
eObjC_VersionUnknown = 0,
4040
eAppleObjC_V1 = 1,
41-
eAppleObjC_V2 = 2
41+
eAppleObjC_V2 = 2,
42+
eGNUstep_libobjc2 = 3,
4243
};
4344

4445
typedef lldb::addr_t ObjCISA;

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