1//===-- AppleObjCTrampolineHandler.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 "AppleObjCTrampolineHandler.h"
10#include "AppleThreadPlanStepThroughObjCTrampoline.h"
11
12#include "Plugins/TypeSystem/Clang/TypeSystemClang.h"
13#include "lldb/Breakpoint/StoppointCallbackContext.h"
14#include "lldb/Core/Debugger.h"
15#include "lldb/Core/Module.h"
16#include "lldb/Core/Value.h"
17#include "lldb/Expression/DiagnosticManager.h"
18#include "lldb/Expression/FunctionCaller.h"
19#include "lldb/Expression/UserExpression.h"
20#include "lldb/Expression/UtilityFunction.h"
21#include "lldb/Symbol/Symbol.h"
22#include "lldb/Target/ABI.h"
23#include "lldb/Target/ExecutionContext.h"
24#include "lldb/Target/Process.h"
25#include "lldb/Target/RegisterContext.h"
26#include "lldb/Target/Target.h"
27#include "lldb/Target/Thread.h"
28#include "lldb/Target/ThreadPlanRunToAddress.h"
29#include "lldb/Utility/ConstString.h"
30#include "lldb/Utility/FileSpec.h"
31#include "lldb/Utility/LLDBLog.h"
32#include "lldb/Utility/Log.h"
33
34#include "llvm/ADT/STLExtras.h"
35#include "llvm/ADT/ScopeExit.h"
36
37#include "Plugins/LanguageRuntime/ObjC/ObjCLanguageRuntime.h"
38
39#include <memory>
40
41using namespace lldb;
42using namespace lldb_private;
43
44const char *AppleObjCTrampolineHandler::g_lookup_implementation_function_name =
45 "__lldb_objc_find_implementation_for_selector";
46const char *AppleObjCTrampolineHandler::
47 g_lookup_implementation_with_stret_function_code =
48 R"(
49 if (is_stret) {
50 return_struct.impl_addr =
51 class_getMethodImplementation_stret (return_struct.class_addr,
52 return_struct.sel_addr);
53 } else {
54 return_struct.impl_addr =
55 class_getMethodImplementation (return_struct.class_addr,
56 return_struct.sel_addr);
57 }
58 if (debug)
59 printf ("\n*** Returning implementation: %p.\n",
60 return_struct.impl_addr);
61
62 return return_struct.impl_addr;
63}
64)";
65const char *
66 AppleObjCTrampolineHandler::g_lookup_implementation_no_stret_function_code =
67 R"(
68 return_struct.impl_addr =
69 class_getMethodImplementation (return_struct.class_addr,
70 return_struct.sel_addr);
71 if (debug)
72 printf ("\n*** getMethodImpletation for addr: 0x%p sel: 0x%p result: 0x%p.\n",
73 return_struct.class_addr, return_struct.sel_addr, return_struct.impl_addr);
74
75 return return_struct.impl_addr;
76}
77)";
78
79const char
80 *AppleObjCTrampolineHandler::g_lookup_implementation_function_common_code =
81 R"(
82extern "C"
83{
84 extern void *class_getMethodImplementation(void *objc_class, void *sel);
85 extern void *class_getMethodImplementation_stret(void *objc_class, void *sel);
86 extern void * object_getClass (id object);
87 extern void * sel_getUid(char *name);
88 extern int printf(const char *format, ...);
89}
90extern "C" void *
91__lldb_objc_find_implementation_for_selector (void *object,
92 void *sel,
93 int is_str_ptr,
94 int is_stret,
95 int is_super,
96 int is_super2,
97 int is_fixup,
98 int is_fixed,
99 int debug)
100{
101 struct __lldb_imp_return_struct {
102 void *class_addr;
103 void *sel_addr;
104 void *impl_addr;
105 };
106
107 struct __lldb_objc_class {
108 void *isa;
109 void *super_ptr;
110 };
111 struct __lldb_objc_super {
112 void *receiver;
113 struct __lldb_objc_class *class_ptr;
114 };
115 struct __lldb_msg_ref {
116 void *dont_know;
117 void *sel;
118 };
119
120 struct __lldb_imp_return_struct return_struct;
121
122 if (debug)
123 printf ("\n*** Called with obj: %p sel: %p is_str_ptr: %d "
124 "is_stret: %d is_super: %d, "
125 "is_super2: %d, is_fixup: %d, is_fixed: %d\n",
126 object, sel, is_str_ptr, is_stret,
127 is_super, is_super2, is_fixup, is_fixed);
128
129 if (is_str_ptr) {
130 if (debug)
131 printf("*** Turning string: '%s'", sel);
132 sel = sel_getUid((char *)sel);
133 if (debug)
134 printf("*** into sel to %p", sel);
135 }
136 if (is_super) {
137 if (is_super2) {
138 return_struct.class_addr
139 = ((__lldb_objc_super *) object)->class_ptr->super_ptr;
140 } else {
141 return_struct.class_addr = ((__lldb_objc_super *) object)->class_ptr;
142 }
143 if (debug)
144 printf("*** Super, class addr: %p\n", return_struct.class_addr);
145 } else {
146 // This code seems a little funny, but has its reasons...
147 // The call to [object class] is here because if this is a class, and has
148 // not been called into yet, we need to do something to force the class to
149 // initialize itself.
150 // Then the call to object_getClass will actually return the correct class,
151 // either the class if object is a class instance, or the meta-class if it
152 // is a class pointer.
153 void *class_ptr = (void *) [(id) object class];
154 return_struct.class_addr = (id) object_getClass((id) object);
155 if (debug) {
156 if (class_ptr == object) {
157 printf ("Found a class object, need to return the meta class %p -> %p\n",
158 class_ptr, return_struct.class_addr);
159 } else {
160 printf ("[object class] returned: %p object_getClass: %p.\n",
161 class_ptr, return_struct.class_addr);
162 }
163 }
164 }
165
166 if (is_fixup) {
167 if (is_fixed) {
168 return_struct.sel_addr = ((__lldb_msg_ref *) sel)->sel;
169 } else {
170 char *sel_name = (char *) ((__lldb_msg_ref *) sel)->sel;
171 return_struct.sel_addr = sel_getUid (sel_name);
172 if (debug)
173 printf ("\n*** Got fixed up selector: %p for name %s.\n",
174 return_struct.sel_addr, sel_name);
175 }
176 } else {
177 return_struct.sel_addr = sel;
178 }
179)";
180
181AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion::VTableRegion(
182 AppleObjCVTables *owner, lldb::addr_t header_addr)
183 : m_valid(true), m_owner(owner), m_header_addr(header_addr) {
184 SetUpRegion();
185}
186
187AppleObjCTrampolineHandler::~AppleObjCTrampolineHandler() = default;
188
189void AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion::SetUpRegion() {
190 // The header looks like:
191 //
192 // uint16_t headerSize
193 // uint16_t descSize
194 // uint32_t descCount
195 // void * next
196 //
197 // First read in the header:
198
199 char memory_buffer[16];
200 ProcessSP process_sp = m_owner->GetProcessSP();
201 if (!process_sp)
202 return;
203 DataExtractor data(memory_buffer, sizeof(memory_buffer),
204 process_sp->GetByteOrder(),
205 process_sp->GetAddressByteSize());
206 size_t actual_size = 8 + process_sp->GetAddressByteSize();
207 Status error;
208 size_t bytes_read =
209 process_sp->ReadMemory(vm_addr: m_header_addr, buf: memory_buffer, size: actual_size, error);
210 if (bytes_read != actual_size) {
211 m_valid = false;
212 return;
213 }
214
215 lldb::offset_t offset = 0;
216 const uint16_t header_size = data.GetU16(offset_ptr: &offset);
217 const uint16_t descriptor_size = data.GetU16(offset_ptr: &offset);
218 const size_t num_descriptors = data.GetU32(offset_ptr: &offset);
219
220 m_next_region = data.GetAddress(offset_ptr: &offset);
221
222 // If the header size is 0, that means we've come in too early before this
223 // data is set up.
224 // Set ourselves as not valid, and continue.
225 if (header_size == 0 || num_descriptors == 0) {
226 m_valid = false;
227 return;
228 }
229
230 // Now read in all the descriptors:
231 // The descriptor looks like:
232 //
233 // uint32_t offset
234 // uint32_t flags
235 //
236 // Where offset is either 0 - in which case it is unused, or it is
237 // the offset of the vtable code from the beginning of the
238 // descriptor record. Below, we'll convert that into an absolute
239 // code address, since I don't want to have to compute it over and
240 // over.
241
242 // Ingest the whole descriptor array:
243 const lldb::addr_t desc_ptr = m_header_addr + header_size;
244 const size_t desc_array_size = num_descriptors * descriptor_size;
245 WritableDataBufferSP data_sp(new DataBufferHeap(desc_array_size, '\0'));
246 uint8_t *dst = (uint8_t *)data_sp->GetBytes();
247
248 DataExtractor desc_extractor(dst, desc_array_size, process_sp->GetByteOrder(),
249 process_sp->GetAddressByteSize());
250 bytes_read = process_sp->ReadMemory(vm_addr: desc_ptr, buf: dst, size: desc_array_size, error);
251 if (bytes_read != desc_array_size) {
252 m_valid = false;
253 return;
254 }
255
256 // The actual code for the vtables will be laid out consecutively, so I also
257 // compute the start and end of the whole code block.
258
259 offset = 0;
260 m_code_start_addr = 0;
261 m_code_end_addr = 0;
262
263 for (size_t i = 0; i < num_descriptors; i++) {
264 lldb::addr_t start_offset = offset;
265 uint32_t voffset = desc_extractor.GetU32(offset_ptr: &offset);
266 uint32_t flags = desc_extractor.GetU32(offset_ptr: &offset);
267 lldb::addr_t code_addr = desc_ptr + start_offset + voffset;
268 m_descriptors.push_back(x: VTableDescriptor(flags, code_addr));
269
270 if (m_code_start_addr == 0 || code_addr < m_code_start_addr)
271 m_code_start_addr = code_addr;
272 if (code_addr > m_code_end_addr)
273 m_code_end_addr = code_addr;
274
275 offset = start_offset + descriptor_size;
276 }
277 // Finally, a little bird told me that all the vtable code blocks
278 // are the same size. Let's compute the blocks and if they are all
279 // the same add the size to the code end address:
280 lldb::addr_t code_size = 0;
281 bool all_the_same = true;
282 for (size_t i = 0; i < num_descriptors - 1; i++) {
283 lldb::addr_t this_size =
284 m_descriptors[i + 1].code_start - m_descriptors[i].code_start;
285 if (code_size == 0)
286 code_size = this_size;
287 else {
288 if (this_size != code_size)
289 all_the_same = false;
290 if (this_size > code_size)
291 code_size = this_size;
292 }
293 }
294 if (all_the_same)
295 m_code_end_addr += code_size;
296}
297
298bool AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion::
299 AddressInRegion(lldb::addr_t addr, uint32_t &flags) {
300 if (!IsValid())
301 return false;
302
303 if (addr < m_code_start_addr || addr > m_code_end_addr)
304 return false;
305
306 std::vector<VTableDescriptor>::iterator pos, end = m_descriptors.end();
307 for (pos = m_descriptors.begin(); pos != end; pos++) {
308 if (addr <= (*pos).code_start) {
309 flags = (*pos).flags;
310 return true;
311 }
312 }
313 return false;
314}
315
316void AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion::Dump(
317 Stream &s) {
318 s.Printf(format: "Header addr: 0x%" PRIx64 " Code start: 0x%" PRIx64
319 " Code End: 0x%" PRIx64 " Next: 0x%" PRIx64 "\n",
320 m_header_addr, m_code_start_addr, m_code_end_addr, m_next_region);
321 size_t num_elements = m_descriptors.size();
322 for (size_t i = 0; i < num_elements; i++) {
323 s.Indent();
324 s.Printf(format: "Code start: 0x%" PRIx64 " Flags: %d\n",
325 m_descriptors[i].code_start, m_descriptors[i].flags);
326 }
327}
328
329AppleObjCTrampolineHandler::AppleObjCVTables::AppleObjCVTables(
330 const ProcessSP &process_sp, const ModuleSP &objc_module_sp)
331 : m_process_wp(), m_trampoline_header(LLDB_INVALID_ADDRESS),
332 m_trampolines_changed_bp_id(LLDB_INVALID_BREAK_ID),
333 m_objc_module_sp(objc_module_sp) {
334 if (process_sp)
335 m_process_wp = process_sp;
336}
337
338AppleObjCTrampolineHandler::AppleObjCVTables::~AppleObjCVTables() {
339 ProcessSP process_sp = GetProcessSP();
340 if (process_sp) {
341 if (m_trampolines_changed_bp_id != LLDB_INVALID_BREAK_ID)
342 process_sp->GetTarget().RemoveBreakpointByID(break_id: m_trampolines_changed_bp_id);
343 }
344}
345
346bool AppleObjCTrampolineHandler::AppleObjCVTables::InitializeVTableSymbols() {
347 if (m_trampoline_header != LLDB_INVALID_ADDRESS)
348 return true;
349
350 ProcessSP process_sp = GetProcessSP();
351 if (process_sp) {
352 Target &target = process_sp->GetTarget();
353
354 if (!m_objc_module_sp) {
355 for (ModuleSP module_sp : target.GetImages().Modules()) {
356 if (ObjCLanguageRuntime::Get(process&: *process_sp)
357 ->IsModuleObjCLibrary(module_sp)) {
358 m_objc_module_sp = module_sp;
359 break;
360 }
361 }
362 }
363
364 if (m_objc_module_sp) {
365 ConstString trampoline_name("gdb_objc_trampolines");
366 const Symbol *trampoline_symbol =
367 m_objc_module_sp->FindFirstSymbolWithNameAndType(name: trampoline_name,
368 symbol_type: eSymbolTypeData);
369 if (trampoline_symbol != nullptr) {
370 m_trampoline_header = trampoline_symbol->GetLoadAddress(target: &target);
371 if (m_trampoline_header == LLDB_INVALID_ADDRESS)
372 return false;
373
374 // Next look up the "changed" symbol and set a breakpoint on that...
375 ConstString changed_name("gdb_objc_trampolines_changed");
376 const Symbol *changed_symbol =
377 m_objc_module_sp->FindFirstSymbolWithNameAndType(name: changed_name,
378 symbol_type: eSymbolTypeCode);
379 if (changed_symbol != nullptr) {
380 const Address changed_symbol_addr = changed_symbol->GetAddress();
381 if (!changed_symbol_addr.IsValid())
382 return false;
383
384 lldb::addr_t changed_addr =
385 changed_symbol_addr.GetOpcodeLoadAddress(target: &target);
386 if (changed_addr != LLDB_INVALID_ADDRESS) {
387 BreakpointSP trampolines_changed_bp_sp =
388 target.CreateBreakpoint(load_addr: changed_addr, internal: true, request_hardware: false);
389 if (trampolines_changed_bp_sp) {
390 m_trampolines_changed_bp_id = trampolines_changed_bp_sp->GetID();
391 trampolines_changed_bp_sp->SetCallback(callback: RefreshTrampolines, baton: this,
392 is_synchronous: true);
393 trampolines_changed_bp_sp->SetBreakpointKind(
394 "objc-trampolines-changed");
395 return true;
396 }
397 }
398 }
399 }
400 }
401 }
402 return false;
403}
404
405bool AppleObjCTrampolineHandler::AppleObjCVTables::RefreshTrampolines(
406 void *baton, StoppointCallbackContext *context, lldb::user_id_t break_id,
407 lldb::user_id_t break_loc_id) {
408 AppleObjCVTables *vtable_handler = (AppleObjCVTables *)baton;
409 if (vtable_handler->InitializeVTableSymbols()) {
410 // The Update function is called with the address of an added region. So we
411 // grab that address, and
412 // feed it into ReadRegions. Of course, our friend the ABI will get the
413 // values for us.
414 ExecutionContext exe_ctx(context->exe_ctx_ref);
415 Process *process = exe_ctx.GetProcessPtr();
416 const ABI *abi = process->GetABI().get();
417
418 TypeSystemClangSP scratch_ts_sp =
419 ScratchTypeSystemClang::GetForTarget(target&: process->GetTarget());
420 if (!scratch_ts_sp)
421 return false;
422
423 ValueList argument_values;
424 Value input_value;
425 CompilerType clang_void_ptr_type =
426 scratch_ts_sp->GetBasicType(type: eBasicTypeVoid).GetPointerType();
427
428 input_value.SetValueType(Value::ValueType::Scalar);
429 // input_value.SetContext (Value::eContextTypeClangType,
430 // clang_void_ptr_type);
431 input_value.SetCompilerType(clang_void_ptr_type);
432 argument_values.PushValue(value: input_value);
433
434 bool success =
435 abi->GetArgumentValues(thread&: exe_ctx.GetThreadRef(), values&: argument_values);
436 if (!success)
437 return false;
438
439 // Now get a pointer value from the zeroth argument.
440 Status error;
441 DataExtractor data;
442 error = argument_values.GetValueAtIndex(idx: 0)->GetValueAsData(exe_ctx: &exe_ctx, data,
443 module: nullptr);
444 lldb::offset_t offset = 0;
445 lldb::addr_t region_addr = data.GetAddress(offset_ptr: &offset);
446
447 if (region_addr != 0)
448 vtable_handler->ReadRegions(region_addr);
449 }
450 return false;
451}
452
453bool AppleObjCTrampolineHandler::AppleObjCVTables::ReadRegions() {
454 // The no argument version reads the start region from the value of
455 // the gdb_regions_header, and gets started from there.
456
457 m_regions.clear();
458 if (!InitializeVTableSymbols())
459 return false;
460 Status error;
461 ProcessSP process_sp = GetProcessSP();
462 if (process_sp) {
463 lldb::addr_t region_addr =
464 process_sp->ReadPointerFromMemory(vm_addr: m_trampoline_header, error);
465 if (error.Success())
466 return ReadRegions(region_addr);
467 }
468 return false;
469}
470
471bool AppleObjCTrampolineHandler::AppleObjCVTables::ReadRegions(
472 lldb::addr_t region_addr) {
473 ProcessSP process_sp = GetProcessSP();
474 if (!process_sp)
475 return false;
476
477 Log *log = GetLog(mask: LLDBLog::Step);
478
479 // We aren't starting at the trampoline symbol.
480 InitializeVTableSymbols();
481 lldb::addr_t next_region = region_addr;
482
483 // Read in the sizes of the headers.
484 while (next_region != 0) {
485 m_regions.push_back(x: VTableRegion(this, next_region));
486 if (!m_regions.back().IsValid()) {
487 m_regions.clear();
488 return false;
489 }
490 if (log) {
491 StreamString s;
492 m_regions.back().Dump(s);
493 LLDB_LOGF(log, "Read vtable region: \n%s", s.GetData());
494 }
495
496 next_region = m_regions.back().GetNextRegionAddr();
497 }
498
499 return true;
500}
501
502bool AppleObjCTrampolineHandler::AppleObjCVTables::IsAddressInVTables(
503 lldb::addr_t addr, uint32_t &flags) {
504 region_collection::iterator pos, end = m_regions.end();
505 for (pos = m_regions.begin(); pos != end; pos++) {
506 if ((*pos).AddressInRegion(addr, flags))
507 return true;
508 }
509 return false;
510}
511
512const AppleObjCTrampolineHandler::DispatchFunction
513 AppleObjCTrampolineHandler::g_dispatch_functions[] = {
514 // NAME STRET SUPER SUPER2 FIXUP TYPE
515 {.name: "objc_msgSend", .stret_return: false, .is_super: false, .is_super2: false, .fixedup: DispatchFunction::eFixUpNone},
516 {.name: "objc_msgSend_fixup", .stret_return: false, .is_super: false, .is_super2: false,
517 .fixedup: DispatchFunction::eFixUpToFix},
518 {.name: "objc_msgSend_fixedup", .stret_return: false, .is_super: false, .is_super2: false,
519 .fixedup: DispatchFunction::eFixUpFixed},
520 {.name: "objc_msgSend_stret", .stret_return: true, .is_super: false, .is_super2: false,
521 .fixedup: DispatchFunction::eFixUpNone},
522 {.name: "objc_msgSend_stret_fixup", .stret_return: true, .is_super: false, .is_super2: false,
523 .fixedup: DispatchFunction::eFixUpToFix},
524 {.name: "objc_msgSend_stret_fixedup", .stret_return: true, .is_super: false, .is_super2: false,
525 .fixedup: DispatchFunction::eFixUpFixed},
526 {.name: "objc_msgSend_fpret", .stret_return: false, .is_super: false, .is_super2: false,
527 .fixedup: DispatchFunction::eFixUpNone},
528 {.name: "objc_msgSend_fpret_fixup", .stret_return: false, .is_super: false, .is_super2: false,
529 .fixedup: DispatchFunction::eFixUpToFix},
530 {.name: "objc_msgSend_fpret_fixedup", .stret_return: false, .is_super: false, .is_super2: false,
531 .fixedup: DispatchFunction::eFixUpFixed},
532 {.name: "objc_msgSend_fp2ret", .stret_return: false, .is_super: false, .is_super2: true,
533 .fixedup: DispatchFunction::eFixUpNone},
534 {.name: "objc_msgSend_fp2ret_fixup", .stret_return: false, .is_super: false, .is_super2: true,
535 .fixedup: DispatchFunction::eFixUpToFix},
536 {.name: "objc_msgSend_fp2ret_fixedup", .stret_return: false, .is_super: false, .is_super2: true,
537 .fixedup: DispatchFunction::eFixUpFixed},
538 {.name: "objc_msgSendSuper", .stret_return: false, .is_super: true, .is_super2: false, .fixedup: DispatchFunction::eFixUpNone},
539 {.name: "objc_msgSendSuper_stret", .stret_return: true, .is_super: true, .is_super2: false,
540 .fixedup: DispatchFunction::eFixUpNone},
541 {.name: "objc_msgSendSuper2", .stret_return: false, .is_super: true, .is_super2: true, .fixedup: DispatchFunction::eFixUpNone},
542 {.name: "objc_msgSendSuper2_fixup", .stret_return: false, .is_super: true, .is_super2: true,
543 .fixedup: DispatchFunction::eFixUpToFix},
544 {.name: "objc_msgSendSuper2_fixedup", .stret_return: false, .is_super: true, .is_super2: true,
545 .fixedup: DispatchFunction::eFixUpFixed},
546 {.name: "objc_msgSendSuper2_stret", .stret_return: true, .is_super: true, .is_super2: true,
547 .fixedup: DispatchFunction::eFixUpNone},
548 {.name: "objc_msgSendSuper2_stret_fixup", .stret_return: true, .is_super: true, .is_super2: true,
549 .fixedup: DispatchFunction::eFixUpToFix},
550 {.name: "objc_msgSendSuper2_stret_fixedup", .stret_return: true, .is_super: true, .is_super2: true,
551 .fixedup: DispatchFunction::eFixUpFixed},
552};
553
554// This is the table of ObjC "accelerated dispatch" functions. They are a set
555// of objc methods that are "seldom overridden" and so the compiler replaces the
556// objc_msgSend with a call to one of the dispatch functions. That will check
557// whether the method has been overridden, and directly call the Foundation
558// implementation if not.
559// This table is supposed to be complete. If ones get added in the future, we
560// will have to add them to the table.
561const char *AppleObjCTrampolineHandler::g_opt_dispatch_names[] = {
562 "objc_alloc",
563 "objc_autorelease",
564 "objc_release",
565 "objc_retain",
566 "objc_alloc_init",
567 "objc_allocWithZone",
568 "objc_opt_class",
569 "objc_opt_isKindOfClass",
570 "objc_opt_new",
571 "objc_opt_respondsToSelector",
572 "objc_opt_self",
573};
574
575AppleObjCTrampolineHandler::AppleObjCTrampolineHandler(
576 const ProcessSP &process_sp, const ModuleSP &objc_module_sp)
577 : m_process_wp(), m_objc_module_sp(objc_module_sp),
578 m_impl_fn_addr(LLDB_INVALID_ADDRESS),
579 m_impl_stret_fn_addr(LLDB_INVALID_ADDRESS),
580 m_msg_forward_addr(LLDB_INVALID_ADDRESS),
581 m_msg_forward_stret_addr(LLDB_INVALID_ADDRESS) {
582 if (process_sp)
583 m_process_wp = process_sp;
584 // Look up the known resolution functions:
585
586 ConstString get_impl_name("class_getMethodImplementation");
587 ConstString get_impl_stret_name("class_getMethodImplementation_stret");
588 ConstString msg_forward_name("_objc_msgForward");
589 ConstString msg_forward_stret_name("_objc_msgForward_stret");
590
591 Target *target = process_sp ? &process_sp->GetTarget() : nullptr;
592 const Symbol *class_getMethodImplementation =
593 m_objc_module_sp->FindFirstSymbolWithNameAndType(name: get_impl_name,
594 symbol_type: eSymbolTypeCode);
595 const Symbol *class_getMethodImplementation_stret =
596 m_objc_module_sp->FindFirstSymbolWithNameAndType(name: get_impl_stret_name,
597 symbol_type: eSymbolTypeCode);
598 const Symbol *msg_forward = m_objc_module_sp->FindFirstSymbolWithNameAndType(
599 name: msg_forward_name, symbol_type: eSymbolTypeCode);
600 const Symbol *msg_forward_stret =
601 m_objc_module_sp->FindFirstSymbolWithNameAndType(name: msg_forward_stret_name,
602 symbol_type: eSymbolTypeCode);
603
604 if (class_getMethodImplementation)
605 m_impl_fn_addr =
606 class_getMethodImplementation->GetAddress().GetOpcodeLoadAddress(
607 target);
608 if (class_getMethodImplementation_stret)
609 m_impl_stret_fn_addr =
610 class_getMethodImplementation_stret->GetAddress().GetOpcodeLoadAddress(
611 target);
612 if (msg_forward)
613 m_msg_forward_addr = msg_forward->GetAddress().GetOpcodeLoadAddress(target);
614 if (msg_forward_stret)
615 m_msg_forward_stret_addr =
616 msg_forward_stret->GetAddress().GetOpcodeLoadAddress(target);
617
618 // FIXME: Do some kind of logging here.
619 if (m_impl_fn_addr == LLDB_INVALID_ADDRESS) {
620 // If we can't even find the ordinary get method implementation function,
621 // then we aren't going to be able to
622 // step through any method dispatches. Warn to that effect and get out of
623 // here.
624 if (process_sp->CanJIT()) {
625 process_sp->GetTarget().GetDebugger().GetErrorStream().Printf(
626 format: "Could not find implementation lookup function \"%s\""
627 " step in through ObjC method dispatch will not work.\n",
628 get_impl_name.AsCString());
629 }
630 return;
631 }
632
633 // We will either set the implementation to the _stret or non_stret version,
634 // so either way it's safe to start filling the m_lookup_..._code here.
635 m_lookup_implementation_function_code.assign(
636 s: g_lookup_implementation_function_common_code);
637
638 if (m_impl_stret_fn_addr == LLDB_INVALID_ADDRESS) {
639 // It there is no stret return lookup function, assume that it is the same
640 // as the straight lookup:
641 m_impl_stret_fn_addr = m_impl_fn_addr;
642 // Also we will use the version of the lookup code that doesn't rely on the
643 // stret version of the function.
644 m_lookup_implementation_function_code.append(
645 s: g_lookup_implementation_no_stret_function_code);
646 } else {
647 m_lookup_implementation_function_code.append(
648 s: g_lookup_implementation_with_stret_function_code);
649 }
650
651 // Look up the addresses for the objc dispatch functions and cache
652 // them. For now I'm inspecting the symbol names dynamically to
653 // figure out how to dispatch to them. If it becomes more
654 // complicated than this we can turn the g_dispatch_functions char *
655 // array into a template table, and populate the DispatchFunction
656 // map from there.
657
658 for (size_t i = 0; i != std::size(g_dispatch_functions); i++) {
659 ConstString name_const_str(g_dispatch_functions[i].name);
660 const Symbol *msgSend_symbol =
661 m_objc_module_sp->FindFirstSymbolWithNameAndType(name: name_const_str,
662 symbol_type: eSymbolTypeCode);
663 if (msgSend_symbol && msgSend_symbol->ValueIsAddress()) {
664 // FIXME: Make g_dispatch_functions static table of
665 // DispatchFunctions, and have the map be address->index.
666 // Problem is we also need to lookup the dispatch function. For
667 // now we could have a side table of stret & non-stret dispatch
668 // functions. If that's as complex as it gets, we're fine.
669
670 lldb::addr_t sym_addr =
671 msgSend_symbol->GetAddressRef().GetOpcodeLoadAddress(target);
672
673 m_msgSend_map.insert(x: std::pair<lldb::addr_t, int>(sym_addr, i));
674 }
675 }
676
677 // Similarly, cache the addresses of the "optimized dispatch" function.
678 for (size_t i = 0; i != std::size(g_opt_dispatch_names); i++) {
679 ConstString name_const_str(g_opt_dispatch_names[i]);
680 const Symbol *msgSend_symbol =
681 m_objc_module_sp->FindFirstSymbolWithNameAndType(name: name_const_str,
682 symbol_type: eSymbolTypeCode);
683 if (msgSend_symbol && msgSend_symbol->ValueIsAddress()) {
684 lldb::addr_t sym_addr =
685 msgSend_symbol->GetAddressRef().GetOpcodeLoadAddress(target);
686
687 m_opt_dispatch_map.emplace(args&: sym_addr, args&: i);
688 }
689 }
690
691 // Build our vtable dispatch handler here:
692 m_vtables_up =
693 std::make_unique<AppleObjCVTables>(args: process_sp, args&: m_objc_module_sp);
694 if (m_vtables_up)
695 m_vtables_up->ReadRegions();
696}
697
698lldb::addr_t
699AppleObjCTrampolineHandler::SetupDispatchFunction(Thread &thread,
700 ValueList &dispatch_values) {
701 ThreadSP thread_sp(thread.shared_from_this());
702 ExecutionContext exe_ctx(thread_sp);
703 Log *log = GetLog(mask: LLDBLog::Step);
704
705 lldb::addr_t args_addr = LLDB_INVALID_ADDRESS;
706 FunctionCaller *impl_function_caller = nullptr;
707
708 // Scope for mutex locker:
709 {
710 std::lock_guard<std::mutex> guard(m_impl_function_mutex);
711
712 // First stage is to make the ClangUtility to hold our injected function:
713
714 if (!m_impl_code) {
715 if (!m_lookup_implementation_function_code.empty()) {
716 auto utility_fn_or_error = exe_ctx.GetTargetRef().CreateUtilityFunction(
717 expression: m_lookup_implementation_function_code,
718 name: g_lookup_implementation_function_name, language: eLanguageTypeC, exe_ctx);
719 if (!utility_fn_or_error) {
720 LLDB_LOG_ERROR(
721 log, utility_fn_or_error.takeError(),
722 "Failed to get Utility Function for implementation lookup: {0}.");
723 return args_addr;
724 }
725 m_impl_code = std::move(*utility_fn_or_error);
726 } else {
727 LLDB_LOGF(log, "No method lookup implementation code.");
728 return LLDB_INVALID_ADDRESS;
729 }
730
731 // Next make the runner function for our implementation utility function.
732 TypeSystemClangSP scratch_ts_sp = ScratchTypeSystemClang::GetForTarget(
733 target&: thread.GetProcess()->GetTarget());
734 if (!scratch_ts_sp)
735 return LLDB_INVALID_ADDRESS;
736
737 CompilerType clang_void_ptr_type =
738 scratch_ts_sp->GetBasicType(type: eBasicTypeVoid).GetPointerType();
739 Status error;
740
741 impl_function_caller = m_impl_code->MakeFunctionCaller(
742 return_type: clang_void_ptr_type, arg_value_list: dispatch_values, compilation_thread: thread_sp, error);
743 if (error.Fail()) {
744 LLDB_LOGF(log,
745 "Error getting function caller for dispatch lookup: \"%s\".",
746 error.AsCString());
747 return args_addr;
748 }
749 } else {
750 impl_function_caller = m_impl_code->GetFunctionCaller();
751 }
752 }
753
754 // Now write down the argument values for this particular call.
755 // This looks like it might be a race condition if other threads
756 // were calling into here, but actually it isn't because we allocate
757 // a new args structure for this call by passing args_addr =
758 // LLDB_INVALID_ADDRESS...
759
760 DiagnosticManager diagnostics;
761 if (!impl_function_caller->WriteFunctionArguments(
762 exe_ctx, args_addr_ref&: args_addr, arg_values&: dispatch_values, diagnostic_manager&: diagnostics)) {
763 if (log) {
764 LLDB_LOGF(log, "Error writing function arguments.");
765 diagnostics.Dump(log);
766 }
767 return args_addr;
768 }
769
770 return args_addr;
771}
772
773const AppleObjCTrampolineHandler::DispatchFunction *
774AppleObjCTrampolineHandler::FindDispatchFunction(lldb::addr_t addr) {
775 MsgsendMap::iterator pos;
776 pos = m_msgSend_map.find(x: addr);
777 if (pos != m_msgSend_map.end()) {
778 return &g_dispatch_functions[(*pos).second];
779 }
780 return nullptr;
781}
782
783void AppleObjCTrampolineHandler::ForEachDispatchFunction(
784 std::function<void(lldb::addr_t, const DispatchFunction &)> callback) {
785 for (auto elem : m_msgSend_map) {
786 callback(elem.first, g_dispatch_functions[elem.second]);
787 }
788}
789
790ThreadPlanSP
791AppleObjCTrampolineHandler::GetStepThroughDispatchPlan(Thread &thread,
792 bool stop_others) {
793 ThreadPlanSP ret_plan_sp;
794 lldb::addr_t curr_pc = thread.GetRegisterContext()->GetPC();
795
796 DispatchFunction vtable_dispatch = {.name: "vtable", .stret_return: false, .is_super: false, .is_super2: false,
797 .fixedup: DispatchFunction::eFixUpFixed};
798 // The selector specific stubs are a wrapper for objc_msgSend. They don't get
799 // passed a SEL, but instead the selector string is encoded in the stub
800 // name, in the form:
801 // objc_msgSend$SelectorName
802 // and the stub figures out the uniqued selector. If we find ourselves in
803 // one of these stubs, we strip off the selector string and pass that to the
804 // implementation finder function, which looks up the SEL (you have to do this
805 // in process) and passes that to the runtime lookup function.
806 DispatchFunction sel_stub_dispatch = {.name: "sel-specific-stub", .stret_return: false, .is_super: false,
807 .is_super2: false, .fixedup: DispatchFunction::eFixUpNone};
808
809 // First step is to see if we're in a selector-specific dispatch stub.
810 // Those are of the form _objc_msgSend$<SELECTOR>, so see if the current
811 // function has that name:
812 Address func_addr;
813 Target &target = thread.GetProcess()->GetTarget();
814 llvm::StringRef sym_name;
815 const DispatchFunction *this_dispatch = nullptr;
816
817 if (target.ResolveLoadAddress(load_addr: curr_pc, so_addr&: func_addr)) {
818 Symbol *curr_sym = func_addr.CalculateSymbolContextSymbol();
819 if (curr_sym)
820 sym_name = curr_sym->GetName().GetStringRef();
821
822 if (!sym_name.empty() && !sym_name.consume_front(Prefix: "objc_msgSend$"))
823 sym_name = {};
824 else
825 this_dispatch = &sel_stub_dispatch;
826 }
827 bool in_selector_stub = !sym_name.empty();
828 // Second step is to look and see if we are in one of the known ObjC
829 // dispatch functions. We've already compiled a table of same, so
830 // consult it.
831
832 if (!in_selector_stub)
833 this_dispatch = FindDispatchFunction(addr: curr_pc);
834
835 // Next check to see if we are in a vtable region:
836
837 if (!this_dispatch && m_vtables_up) {
838 uint32_t flags;
839 if (m_vtables_up->IsAddressInVTables(addr: curr_pc, flags)) {
840 vtable_dispatch.stret_return =
841 (flags & AppleObjCVTables::eOBJC_TRAMPOLINE_STRET) ==
842 AppleObjCVTables::eOBJC_TRAMPOLINE_STRET;
843 this_dispatch = &vtable_dispatch;
844 }
845 }
846
847 // Since we set this_dispatch in both the vtable & sel specific stub cases
848 // this if will be used for all three of those cases.
849 if (this_dispatch) {
850 Log *log = GetLog(mask: LLDBLog::Step);
851
852 // We are decoding a method dispatch. First job is to pull the
853 // arguments out. If we are in a regular stub, we get self & selector,
854 // but if we are in a selector-specific stub, we'll have to get that from
855 // the string sym_name.
856
857 lldb::StackFrameSP thread_cur_frame = thread.GetStackFrameAtIndex(idx: 0);
858
859 const ABI *abi = nullptr;
860 ProcessSP process_sp(thread.CalculateProcess());
861 if (process_sp)
862 abi = process_sp->GetABI().get();
863 if (abi == nullptr)
864 return ret_plan_sp;
865
866 TargetSP target_sp(thread.CalculateTarget());
867
868 TypeSystemClangSP scratch_ts_sp =
869 ScratchTypeSystemClang::GetForTarget(target&: *target_sp);
870 if (!scratch_ts_sp)
871 return ret_plan_sp;
872
873 ValueList argument_values;
874 Value void_ptr_value;
875 CompilerType clang_void_ptr_type =
876 scratch_ts_sp->GetBasicType(type: eBasicTypeVoid).GetPointerType();
877 void_ptr_value.SetValueType(Value::ValueType::Scalar);
878 // void_ptr_value.SetContext (Value::eContextTypeClangType,
879 // clang_void_ptr_type);
880 void_ptr_value.SetCompilerType(clang_void_ptr_type);
881
882 int obj_index;
883 int sel_index;
884
885 // If this is a selector-specific stub then just push one value, 'cause
886 // we only get the object.
887 // If this is a struct return dispatch, then the first argument is
888 // the return struct pointer, and the object is the second, and
889 // the selector is the third.
890 // Otherwise the object is the first and the selector the second.
891 if (in_selector_stub) {
892 obj_index = 0;
893 sel_index = 1;
894 argument_values.PushValue(value: void_ptr_value);
895 } else if (this_dispatch->stret_return) {
896 obj_index = 1;
897 sel_index = 2;
898 argument_values.PushValue(value: void_ptr_value);
899 argument_values.PushValue(value: void_ptr_value);
900 argument_values.PushValue(value: void_ptr_value);
901 } else {
902 obj_index = 0;
903 sel_index = 1;
904 argument_values.PushValue(value: void_ptr_value);
905 argument_values.PushValue(value: void_ptr_value);
906 }
907
908 bool success = abi->GetArgumentValues(thread, values&: argument_values);
909 if (!success)
910 return ret_plan_sp;
911
912 lldb::addr_t obj_addr =
913 argument_values.GetValueAtIndex(idx: obj_index)->GetScalar().ULongLong();
914 if (obj_addr == 0x0) {
915 LLDB_LOGF(
916 log,
917 "Asked to step to dispatch to nil object, returning empty plan.");
918 return ret_plan_sp;
919 }
920
921 ExecutionContext exe_ctx(thread.shared_from_this());
922 // isa_addr will store the class pointer that the method is being
923 // dispatched to - so either the class directly or the super class
924 // if this is one of the objc_msgSendSuper flavors. That's mostly
925 // used to look up the class/selector pair in our cache.
926
927 lldb::addr_t isa_addr = LLDB_INVALID_ADDRESS;
928 lldb::addr_t sel_addr = LLDB_INVALID_ADDRESS;
929 // If we are not in a selector stub, get the sel address from the arguments.
930 if (!in_selector_stub)
931 sel_addr =
932 argument_values.GetValueAtIndex(idx: sel_index)->GetScalar().ULongLong();
933
934 // Figure out the class this is being dispatched to and see if
935 // we've already cached this method call, If so we can push a
936 // run-to-address plan directly. Otherwise we have to figure out
937 // where the implementation lives.
938
939 if (this_dispatch->is_super) {
940 if (this_dispatch->is_super2) {
941 // In the objc_msgSendSuper2 case, we don't get the object
942 // directly, we get a structure containing the object and the
943 // class to which the super message is being sent. So we need
944 // to dig the super out of the class and use that.
945
946 Value super_value(*(argument_values.GetValueAtIndex(idx: obj_index)));
947 super_value.GetScalar() += process_sp->GetAddressByteSize();
948 super_value.ResolveValue(exe_ctx: &exe_ctx);
949
950 if (super_value.GetScalar().IsValid()) {
951
952 // isa_value now holds the class pointer. The second word of the
953 // class pointer is the super-class pointer:
954 super_value.GetScalar() += process_sp->GetAddressByteSize();
955 super_value.ResolveValue(exe_ctx: &exe_ctx);
956 if (super_value.GetScalar().IsValid())
957 isa_addr = super_value.GetScalar().ULongLong();
958 else {
959 LLDB_LOGF(log, "Failed to extract the super class value from the "
960 "class in objc_super.");
961 }
962 } else {
963 LLDB_LOGF(log, "Failed to extract the class value from objc_super.");
964 }
965 } else {
966 // In the objc_msgSendSuper case, we don't get the object
967 // directly, we get a two element structure containing the
968 // object and the super class to which the super message is
969 // being sent. So the class we want is the second element of
970 // this structure.
971
972 Value super_value(*(argument_values.GetValueAtIndex(idx: obj_index)));
973 super_value.GetScalar() += process_sp->GetAddressByteSize();
974 super_value.ResolveValue(exe_ctx: &exe_ctx);
975
976 if (super_value.GetScalar().IsValid()) {
977 isa_addr = super_value.GetScalar().ULongLong();
978 } else {
979 LLDB_LOGF(log, "Failed to extract the class value from objc_super.");
980 }
981 }
982 } else {
983 // In the direct dispatch case, the object->isa is the class pointer we
984 // want.
985
986 // This is a little cheesy, but since object->isa is the first field,
987 // making the object value a load address value and resolving it will get
988 // the pointer sized data pointed to by that value...
989
990 // Note, it isn't a fatal error not to be able to get the
991 // address from the object, since this might be a "tagged
992 // pointer" which isn't a real object, but rather some word
993 // length encoded dingus.
994
995 Value isa_value(*(argument_values.GetValueAtIndex(idx: obj_index)));
996
997 isa_value.SetValueType(Value::ValueType::LoadAddress);
998 isa_value.ResolveValue(exe_ctx: &exe_ctx);
999 if (isa_value.GetScalar().IsValid()) {
1000 isa_addr = isa_value.GetScalar().ULongLong();
1001 } else {
1002 LLDB_LOGF(log, "Failed to extract the isa value from object.");
1003 }
1004 }
1005
1006 // Okay, we've got the address of the class for which we're resolving this,
1007 // let's see if it's in our cache:
1008 lldb::addr_t impl_addr = LLDB_INVALID_ADDRESS;
1009 // If this is a regular dispatch, look up the sel in our addr to sel cache:
1010 if (isa_addr != LLDB_INVALID_ADDRESS) {
1011 ObjCLanguageRuntime *objc_runtime =
1012 ObjCLanguageRuntime::Get(process&: *thread.GetProcess());
1013 assert(objc_runtime != nullptr);
1014 if (!in_selector_stub) {
1015 LLDB_LOG(log, "Resolving call for class - {0} and selector - {1}",
1016 isa_addr, sel_addr);
1017 impl_addr = objc_runtime->LookupInMethodCache(class_addr: isa_addr, sel: sel_addr);
1018 } else {
1019 LLDB_LOG(log, "Resolving call for class - {0} and selector - {1}",
1020 isa_addr, sym_name);
1021 impl_addr = objc_runtime->LookupInMethodCache(class_addr: isa_addr, sel_str: sym_name);
1022 }
1023 }
1024 // If it is a selector-specific stub dispatch, look in the string cache:
1025
1026 if (impl_addr != LLDB_INVALID_ADDRESS) {
1027 // Yup, it was in the cache, so we can run to that address directly.
1028
1029 LLDB_LOGF(log, "Found implementation address in cache: 0x%" PRIx64,
1030 impl_addr);
1031
1032 ret_plan_sp = std::make_shared<ThreadPlanRunToAddress>(args&: thread, args&: impl_addr,
1033 args&: stop_others);
1034 } else {
1035 // We haven't seen this class/selector pair yet. Look it up.
1036 StreamString errors;
1037 Address impl_code_address;
1038
1039 ValueList dispatch_values;
1040
1041 // We've will inject a little function in the target that takes the
1042 // object, selector/selector string and some flags,
1043 // and figures out the implementation. Looks like:
1044 // void *__lldb_objc_find_implementation_for_selector (void *object,
1045 // void *sel,
1046 // int
1047 // is_str_ptr,
1048 // int is_stret,
1049 // int is_super,
1050 // int is_super2,
1051 // int is_fixup,
1052 // int is_fixed,
1053 // int debug)
1054 // If we don't have an actual SEL, but rather a string version of the
1055 // selector WE injected, set is_str_ptr to true, and sel to the address
1056 // of the string.
1057 // So set up the arguments for that call.
1058
1059 dispatch_values.PushValue(value: *(argument_values.GetValueAtIndex(idx: obj_index)));
1060 lldb::addr_t sel_str_addr = LLDB_INVALID_ADDRESS;
1061 if (!in_selector_stub) {
1062 // If we don't have a selector string, push the selector from arguments.
1063 dispatch_values.PushValue(
1064 value: *(argument_values.GetValueAtIndex(idx: sel_index)));
1065 } else {
1066 // Otherwise, inject the string into the target, and push that value for
1067 // the sel argument.
1068 Status error;
1069 sel_str_addr = process_sp->AllocateMemory(
1070 size: sym_name.size() + 1, permissions: ePermissionsReadable | ePermissionsWritable,
1071 error);
1072 if (sel_str_addr == LLDB_INVALID_ADDRESS || error.Fail()) {
1073 LLDB_LOG(log,
1074 "Could not allocate memory for selector string {0}: {1}",
1075 sym_name, error);
1076 return ret_plan_sp;
1077 }
1078 process_sp->WriteMemory(vm_addr: sel_str_addr, buf: sym_name.str().c_str(),
1079 size: sym_name.size() + 1, error);
1080 if (error.Fail()) {
1081 LLDB_LOG(log, "Could not write string to address {0}", sel_str_addr);
1082 return ret_plan_sp;
1083 }
1084 Value sel_ptr_value(void_ptr_value);
1085 sel_ptr_value.GetScalar() = sel_str_addr;
1086 dispatch_values.PushValue(value: sel_ptr_value);
1087 }
1088
1089 Value flag_value;
1090 CompilerType clang_int_type =
1091 scratch_ts_sp->GetBuiltinTypeForEncodingAndBitSize(
1092 encoding: lldb::eEncodingSint, bit_size: 32);
1093 flag_value.SetValueType(Value::ValueType::Scalar);
1094 // flag_value.SetContext (Value::eContextTypeClangType, clang_int_type);
1095 flag_value.SetCompilerType(clang_int_type);
1096
1097 if (in_selector_stub)
1098 flag_value.GetScalar() = 1;
1099 else
1100 flag_value.GetScalar() = 0;
1101 dispatch_values.PushValue(value: flag_value);
1102
1103 if (this_dispatch->stret_return)
1104 flag_value.GetScalar() = 1;
1105 else
1106 flag_value.GetScalar() = 0;
1107 dispatch_values.PushValue(value: flag_value);
1108
1109 if (this_dispatch->is_super)
1110 flag_value.GetScalar() = 1;
1111 else
1112 flag_value.GetScalar() = 0;
1113 dispatch_values.PushValue(value: flag_value);
1114
1115 if (this_dispatch->is_super2)
1116 flag_value.GetScalar() = 1;
1117 else
1118 flag_value.GetScalar() = 0;
1119 dispatch_values.PushValue(value: flag_value);
1120
1121 switch (this_dispatch->fixedup) {
1122 case DispatchFunction::eFixUpNone:
1123 flag_value.GetScalar() = 0;
1124 dispatch_values.PushValue(value: flag_value);
1125 dispatch_values.PushValue(value: flag_value);
1126 break;
1127 case DispatchFunction::eFixUpFixed:
1128 flag_value.GetScalar() = 1;
1129 dispatch_values.PushValue(value: flag_value);
1130 flag_value.GetScalar() = 1;
1131 dispatch_values.PushValue(value: flag_value);
1132 break;
1133 case DispatchFunction::eFixUpToFix:
1134 flag_value.GetScalar() = 1;
1135 dispatch_values.PushValue(value: flag_value);
1136 flag_value.GetScalar() = 0;
1137 dispatch_values.PushValue(value: flag_value);
1138 break;
1139 }
1140 if (log && log->GetVerbose())
1141 flag_value.GetScalar() = 1;
1142 else
1143 flag_value.GetScalar() = 0; // FIXME - Set to 0 when debugging is done.
1144 dispatch_values.PushValue(value: flag_value);
1145
1146 ret_plan_sp = std::make_shared<AppleThreadPlanStepThroughObjCTrampoline>(
1147 args&: thread, args&: *this, args&: dispatch_values, args&: isa_addr, args&: sel_addr, args&: sel_str_addr,
1148 args&: sym_name);
1149 if (log) {
1150 StreamString s;
1151 ret_plan_sp->GetDescription(s: &s, level: eDescriptionLevelFull);
1152 LLDB_LOGF(log, "Using ObjC step plan: %s.\n", s.GetData());
1153 }
1154 }
1155 }
1156
1157 // Finally, check if we have hit an "optimized dispatch" function. This will
1158 // either directly call the base implementation or dispatch an objc_msgSend
1159 // if the method has been overridden. So we just do a "step in/step out",
1160 // setting a breakpoint on objc_msgSend, and if we hit the msgSend, we
1161 // will automatically step in again. That's the job of the
1162 // AppleThreadPlanStepThroughDirectDispatch.
1163 if (!this_dispatch && !ret_plan_sp) {
1164 MsgsendMap::iterator pos;
1165 pos = m_opt_dispatch_map.find(x: curr_pc);
1166 if (pos != m_opt_dispatch_map.end()) {
1167 const char *opt_name = g_opt_dispatch_names[(*pos).second];
1168 ret_plan_sp = std::make_shared<AppleThreadPlanStepThroughDirectDispatch>(
1169 args&: thread, args&: *this, args&: opt_name);
1170 }
1171 }
1172
1173 return ret_plan_sp;
1174}
1175
1176FunctionCaller *
1177AppleObjCTrampolineHandler::GetLookupImplementationFunctionCaller() {
1178 return m_impl_code->GetFunctionCaller();
1179}
1180

source code of lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCTrampolineHandler.cpp