contrib/llvm-project/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCTrampolineHandler.cpp

   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/StreamFile.h"
  17 #include "lldb/Core/Value.h"
  18 #include "lldb/Expression/DiagnosticManager.h"
  19 #include "lldb/Expression/FunctionCaller.h"
  20 #include "lldb/Expression/UserExpression.h"
  21 #include "lldb/Expression/UtilityFunction.h"
  22 #include "lldb/Symbol/Symbol.h"
  23 #include "lldb/Target/ABI.h"
  24 #include "lldb/Target/ExecutionContext.h"
  25 #include "lldb/Target/Process.h"
  26 #include "lldb/Target/RegisterContext.h"
  27 #include "lldb/Target/Target.h"
  28 #include "lldb/Target/Thread.h"
  29 #include "lldb/Target/ThreadPlanRunToAddress.h"
  30 #include "lldb/Utility/ConstString.h"
  31 #include "lldb/Utility/FileSpec.h"
  32 #include "lldb/Utility/Log.h"
  33
  34 #include "llvm/ADT/STLExtras.h"
  35
  36 #include "Plugins/LanguageRuntime/ObjC/ObjCLanguageRuntime.h"
  37
  38 #include <memory>
  39
  40 using namespace lldb;
  41 using namespace lldb_private;
  42
  43 const char *AppleObjCTrampolineHandler::g_lookup_implementation_function_name =
  44     "__lldb_objc_find_implementation_for_selector";
  45 const char *AppleObjCTrampolineHandler::
  46     g_lookup_implementation_with_stret_function_code =
  47         "                               \n\
  48 extern \"C\"                                                                 \n\
  49 {                                                                            \n\
  50     extern void *class_getMethodImplementation(void *objc_class, void *sel); \n\
  51     extern void *class_getMethodImplementation_stret(void *objc_class,       \n\
  52                                                      void *sel);             \n\
  53     extern void * object_getClass (id object);                               \n\
  54     extern void * sel_getUid(char *name);                                    \n\
  55     extern int printf(const char *format, ...);                              \n\
  56 }                                                                            \n\
  57 extern \"C\" void * __lldb_objc_find_implementation_for_selector (           \n\
  58                                                     void *object,            \n\
  59                                                     void *sel,               \n\
  60                                                     int is_stret,            \n\
  61                                                     int is_super,            \n\
  62                                                     int is_super2,           \n\
  63                                                     int is_fixup,            \n\
  64                                                     int is_fixed,            \n\
  65                                                     int debug)               \n\
  66 {                                                                            \n\
  67     struct __lldb_imp_return_struct                                          \n\
  68     {                                                                        \n\
  69         void *class_addr;                                                    \n\
  70         void *sel_addr;                                                      \n\
  71         void *impl_addr;                                                     \n\
  72     };                                                                       \n\
  73                                                                              \n\
  74     struct __lldb_objc_class {                                               \n\
  75         void *isa;                                                           \n\
  76         void *super_ptr;                                                     \n\
  77     };                                                                       \n\
  78     struct __lldb_objc_super {                                               \n\
  79         void *receiver;                                                      \n\
  80         struct __lldb_objc_class *class_ptr;                                 \n\
  81     };                                                                       \n\
  82     struct __lldb_msg_ref {                                                  \n\
  83         void *dont_know;                                                     \n\
  84         void *sel;                                                           \n\
  85     };                                                                       \n\
  86                                                                              \n\
  87     struct __lldb_imp_return_struct return_struct;                           \n\
  88                                                                              \n\
  89     if (debug)                                                               \n\
  90         printf (\"\\n*** Called with obj: 0x%p sel: 0x%p is_stret: %d is_super: %d, \"\n\
  91                 \"is_super2: %d, is_fixup: %d, is_fixed: %d\\n\",            \n\
  92                  object, sel, is_stret, is_super, is_super2, is_fixup, is_fixed);\n\
  93     if (is_super)                                                            \n\
  94     {                                                                        \n\
  95         if (is_super2)                                                       \n\
  96         {                                                                    \n\
  97             return_struct.class_addr = ((__lldb_objc_super *) object)->class_ptr->super_ptr;\n\
  98         }                                                                    \n\
  99         else                                                                 \n\
 100         {                                                                    \n\
 101             return_struct.class_addr = ((__lldb_objc_super *) object)->class_ptr;\n\
 102         }                                                                    \n\
 103     }                                                                        \n\
 104     else                                                                     \n\
 105     {                                                                        \n\
 106         // This code seems a little funny, but has its reasons...            \n\
 107                                                                              \n\
 108         // The call to [object class] is here because if this is a           \n\
 109         // class, and has not been called into yet, we need to do            \n\
 110         // something to force the class to initialize itself.                \n\
 111         // Then the call to object_getClass will actually return the         \n\
 112         // correct class, either the class if object is a class              \n\
 113         // instance, or the meta-class if it is a class pointer.             \n\
 114         void *class_ptr = (void *) [(id) object class];                      \n\
 115         return_struct.class_addr = (id)  object_getClass((id) object);       \n\
 116         if (debug)                                                           \n\
 117         {                                                                    \n\
 118             if (class_ptr == object)                                         \n\
 119             {                                                                \n\
 120                 printf (\"Found a class object, need to use the meta class %p -> %p\\n\",\n\
 121                         class_ptr, return_struct.class_addr);                \n\
 122             }                                                                \n\
 123             else                                                             \n\
 124             {                                                                \n\
 125                  printf (\"[object class] returned: %p object_getClass: %p.\\n\", \n\
 126                  class_ptr, return_struct.class_addr);                       \n\
 127             }                                                                \n\
 128         }                                                                    \n\
 129     }                                                                        \n\
 130                                                                              \n\
 131     if (is_fixup)                                                            \n\
 132     {                                                                        \n\
 133         if (is_fixed)                                                        \n\
 134         {                                                                    \n\
 135             return_struct.sel_addr = ((__lldb_msg_ref *) sel)->sel;          \n\
 136         }                                                                    \n\
 137         else                                                                 \n\
 138         {                                                                    \n\
 139             char *sel_name = (char *) ((__lldb_msg_ref *) sel)->sel;         \n\
 140             return_struct.sel_addr = sel_getUid (sel_name);                  \n\
 141             if (debug)                                                       \n\
 142                 printf (\"\\n*** Got fixed up selector: %p for name %s.\\n\",\n\
 143                         return_struct.sel_addr, sel_name);                   \n\
 144         }                                                                    \n\
 145     }                                                                        \n\
 146     else                                                                     \n\
 147     {                                                                        \n\
 148         return_struct.sel_addr = sel;                                        \n\
 149     }                                                                        \n\
 150                                                                              \n\
 151     if (is_stret)                                                            \n\
 152     {                                                                        \n\
 153         return_struct.impl_addr =                                            \n\
 154           class_getMethodImplementation_stret (return_struct.class_addr,     \n\
 155                                                return_struct.sel_addr);      \n\
 156     }                                                                        \n\
 157     else                                                                     \n\
 158     {                                                                        \n\
 159         return_struct.impl_addr =                                            \n\
 160             class_getMethodImplementation (return_struct.class_addr,         \n\
 161                                            return_struct.sel_addr);          \n\
 162     }                                                                        \n\
 163     if (debug)                                                               \n\
 164         printf (\"\\n*** Returning implementation: %p.\\n\",                 \n\
 165                           return_struct.impl_addr);                          \n\
 166                                                                              \n\
 167     return return_struct.impl_addr;                                          \n\
 168 }                                                                            \n\
 169 ";
 170 const char *
 171     AppleObjCTrampolineHandler::g_lookup_implementation_no_stret_function_code =
 172         "                      \n\
 173 extern \"C\"                                                                 \n\
 174 {                                                                            \n\
 175     extern void *class_getMethodImplementation(void *objc_class, void *sel); \n\
 176     extern void * object_getClass (id object);                               \n\
 177     extern void * sel_getUid(char *name);                                    \n\
 178     extern int printf(const char *format, ...);                              \n\
 179 }                                                                            \n\
 180 extern \"C\" void * __lldb_objc_find_implementation_for_selector (void *object,                                 \n\
 181                                                     void *sel,               \n\
 182                                                     int is_stret,            \n\
 183                                                     int is_super,            \n\
 184                                                     int is_super2,           \n\
 185                                                     int is_fixup,            \n\
 186                                                     int is_fixed,            \n\
 187                                                     int debug)               \n\
 188 {                                                                            \n\
 189     struct __lldb_imp_return_struct                                          \n\
 190     {                                                                        \n\
 191         void *class_addr;                                                    \n\
 192         void *sel_addr;                                                      \n\
 193         void *impl_addr;                                                     \n\
 194     };                                                                       \n\
 195                                                                              \n\
 196     struct __lldb_objc_class {                                               \n\
 197         void *isa;                                                           \n\
 198         void *super_ptr;                                                     \n\
 199     };                                                                       \n\
 200     struct __lldb_objc_super {                                               \n\
 201         void *receiver;                                                      \n\
 202         struct __lldb_objc_class *class_ptr;                                 \n\
 203     };                                                                       \n\
 204     struct __lldb_msg_ref {                                                  \n\
 205         void *dont_know;                                                     \n\
 206         void *sel;                                                           \n\
 207     };                                                                       \n\
 208                                                                              \n\
 209     struct __lldb_imp_return_struct return_struct;                           \n\
 210                                                                              \n\
 211     if (debug)                                                               \n\
 212         printf (\"\\n*** Called with obj: 0x%p sel: 0x%p is_stret: %d is_super: %d, \"                          \n\
 213                 \"is_super2: %d, is_fixup: %d, is_fixed: %d\\n\",            \n\
 214                  object, sel, is_stret, is_super, is_super2, is_fixup, is_fixed);                               \n\
 215     if (is_super)                                                            \n\
 216     {                                                                        \n\
 217         if (is_super2)                                                       \n\
 218         {                                                                    \n\
 219             return_struct.class_addr = ((__lldb_objc_super *) object)->class_ptr->super_ptr;                    \n\
 220         }                                                                    \n\
 221         else                                                                 \n\
 222         {                                                                    \n\
 223             return_struct.class_addr = ((__lldb_objc_super *) object)->class_ptr;                               \n\
 224         }                                                                    \n\
 225     }                                                                        \n\
 226     else                                                                     \n\
 227     {                                                                        \n\
 228         // This code seems a little funny, but has its reasons...            \n\
 229         // The call to [object class] is here because if this is a class, and has not been called into          \n\
 230         // yet, we need to do something to force the class to initialize itself.                                \n\
 231         // Then the call to object_getClass will actually return the correct class, either the class            \n\
 232         // if object is a class instance, or the meta-class if it is a class pointer.                           \n\
 233         void *class_ptr = (void *) [(id) object class];                      \n\
 234         return_struct.class_addr = (id)  object_getClass((id) object);       \n\
 235         if (debug)                                                           \n\
 236         {                                                                    \n\
 237             if (class_ptr == object)                                         \n\
 238             {                                                                \n\
 239                 printf (\"Found a class object, need to return the meta class %p -> %p\\n\",                    \n\
 240                         class_ptr, return_struct.class_addr);                \n\
 241             }                                                                \n\
 242             else                                                             \n\
 243             {                                                                \n\
 244                  printf (\"[object class] returned: %p object_getClass: %p.\\n\",                               \n\
 245                  class_ptr, return_struct.class_addr);                       \n\
 246             }                                                                \n\
 247         }                                                                    \n\
 248     }                                                                        \n\
 249                                                                              \n\
 250     if (is_fixup)                                                            \n\
 251     {                                                                        \n\
 252         if (is_fixed)                                                        \n\
 253         {                                                                    \n\
 254             return_struct.sel_addr = ((__lldb_msg_ref *) sel)->sel;          \n\
 255         }                                                                    \n\
 256         else                                                                 \n\
 257         {                                                                    \n\
 258             char *sel_name = (char *) ((__lldb_msg_ref *) sel)->sel;         \n\
 259             return_struct.sel_addr = sel_getUid (sel_name);                  \n\
 260             if (debug)                                                       \n\
 261                 printf (\"\\n*** Got fixed up selector: %p for name %s.\\n\",\n\
 262                         return_struct.sel_addr, sel_name);                   \n\
 263         }                                                                    \n\
 264     }                                                                        \n\
 265     else                                                                     \n\
 266     {                                                                        \n\
 267         return_struct.sel_addr = sel;                                        \n\
 268     }                                                                        \n\
 269                                                                              \n\
 270     return_struct.impl_addr =                                                \n\
 271       class_getMethodImplementation (return_struct.class_addr,               \n\
 272                                      return_struct.sel_addr);                \n\
 273     if (debug)                                                               \n\
 274         printf (\"\\n*** Returning implementation: 0x%p.\\n\",               \n\
 275           return_struct.impl_addr);                                          \n\
 276                                                                              \n\
 277     return return_struct.impl_addr;                                          \n\
 278 }                                                                            \n\
 279 ";
 280
 281 AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion::VTableRegion(
 282     AppleObjCVTables *owner, lldb::addr_t header_addr)
 283     : m_valid(true), m_owner(owner), m_header_addr(header_addr),
 284       m_code_start_addr(0), m_code_end_addr(0), m_next_region(0) {
 285   SetUpRegion();
 286 }
 287
 288 AppleObjCTrampolineHandler::~AppleObjCTrampolineHandler() {}
 289
 290 void AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion::SetUpRegion() {
 291   // The header looks like:
 292   //
 293   //   uint16_t headerSize
 294   //   uint16_t descSize
 295   //   uint32_t descCount
 296   //   void * next
 297   //
 298   // First read in the header:
 299
 300   char memory_buffer[16];
 301   ProcessSP process_sp = m_owner->GetProcessSP();
 302   if (!process_sp)
 303     return;
 304   DataExtractor data(memory_buffer, sizeof(memory_buffer),
 305                      process_sp->GetByteOrder(),
 306                      process_sp->GetAddressByteSize());
 307   size_t actual_size = 8 + process_sp->GetAddressByteSize();
 308   Status error;
 309   size_t bytes_read =
 310       process_sp->ReadMemory(m_header_addr, memory_buffer, actual_size, error);
 311   if (bytes_read != actual_size) {
 312     m_valid = false;
 313     return;
 314   }
 315
 316   lldb::offset_t offset = 0;
 317   const uint16_t header_size = data.GetU16(&offset);
 318   const uint16_t descriptor_size = data.GetU16(&offset);
 319   const size_t num_descriptors = data.GetU32(&offset);
 320
 321   m_next_region = data.GetAddress(&offset);
 322
 323   // If the header size is 0, that means we've come in too early before this
 324   // data is set up.
 325   // Set ourselves as not valid, and continue.
 326   if (header_size == 0 || num_descriptors == 0) {
 327     m_valid = false;
 328     return;
 329   }
 330
 331   // Now read in all the descriptors:
 332   // The descriptor looks like:
 333   //
 334   // uint32_t offset
 335   // uint32_t flags
 336   //
 337   // Where offset is either 0 - in which case it is unused, or it is
 338   // the offset of the vtable code from the beginning of the
 339   // descriptor record.  Below, we'll convert that into an absolute
 340   // code address, since I don't want to have to compute it over and
 341   // over.
 342
 343   // Ingest the whole descriptor array:
 344   const lldb::addr_t desc_ptr = m_header_addr + header_size;
 345   const size_t desc_array_size = num_descriptors * descriptor_size;
 346   DataBufferSP data_sp(new DataBufferHeap(desc_array_size, '\0'));
 347   uint8_t *dst = (uint8_t *)data_sp->GetBytes();
 348
 349   DataExtractor desc_extractor(dst, desc_array_size, process_sp->GetByteOrder(),
 350                                process_sp->GetAddressByteSize());
 351   bytes_read = process_sp->ReadMemory(desc_ptr, dst, desc_array_size, error);
 352   if (bytes_read != desc_array_size) {
 353     m_valid = false;
 354     return;
 355   }
 356
 357   // The actual code for the vtables will be laid out consecutively, so I also
 358   // compute the start and end of the whole code block.
 359
 360   offset = 0;
 361   m_code_start_addr = 0;
 362   m_code_end_addr = 0;
 363
 364   for (size_t i = 0; i < num_descriptors; i++) {
 365     lldb::addr_t start_offset = offset;
 366     uint32_t voffset = desc_extractor.GetU32(&offset);
 367     uint32_t flags = desc_extractor.GetU32(&offset);
 368     lldb::addr_t code_addr = desc_ptr + start_offset + voffset;
 369     m_descriptors.push_back(VTableDescriptor(flags, code_addr));
 370
 371     if (m_code_start_addr == 0 || code_addr < m_code_start_addr)
 372       m_code_start_addr = code_addr;
 373     if (code_addr > m_code_end_addr)
 374       m_code_end_addr = code_addr;
 375
 376     offset = start_offset + descriptor_size;
 377   }
 378   // Finally, a little bird told me that all the vtable code blocks
 379   // are the same size.  Let's compute the blocks and if they are all
 380   // the same add the size to the code end address:
 381   lldb::addr_t code_size = 0;
 382   bool all_the_same = true;
 383   for (size_t i = 0; i < num_descriptors - 1; i++) {
 384     lldb::addr_t this_size =
 385         m_descriptors[i + 1].code_start - m_descriptors[i].code_start;
 386     if (code_size == 0)
 387       code_size = this_size;
 388     else {
 389       if (this_size != code_size)
 390         all_the_same = false;
 391       if (this_size > code_size)
 392         code_size = this_size;
 393     }
 394   }
 395   if (all_the_same)
 396     m_code_end_addr += code_size;
 397 }
 398
 399 bool AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion::
 400     AddressInRegion(lldb::addr_t addr, uint32_t &flags) {
 401   if (!IsValid())
 402     return false;
 403
 404   if (addr < m_code_start_addr || addr > m_code_end_addr)
 405     return false;
 406
 407   std::vector<VTableDescriptor>::iterator pos, end = m_descriptors.end();
 408   for (pos = m_descriptors.begin(); pos != end; pos++) {
 409     if (addr <= (*pos).code_start) {
 410       flags = (*pos).flags;
 411       return true;
 412     }
 413   }
 414   return false;
 415 }
 416
 417 void AppleObjCTrampolineHandler::AppleObjCVTables::VTableRegion::Dump(
 418     Stream &s) {
 419   s.Printf("Header addr: 0x%" PRIx64 " Code start: 0x%" PRIx64
 420            " Code End: 0x%" PRIx64 " Next: 0x%" PRIx64 "\n",
 421            m_header_addr, m_code_start_addr, m_code_end_addr, m_next_region);
 422   size_t num_elements = m_descriptors.size();
 423   for (size_t i = 0; i < num_elements; i++) {
 424     s.Indent();
 425     s.Printf("Code start: 0x%" PRIx64 " Flags: %d\n",
 426              m_descriptors[i].code_start, m_descriptors[i].flags);
 427   }
 428 }
 429
 430 AppleObjCTrampolineHandler::AppleObjCVTables::AppleObjCVTables(
 431     const ProcessSP &process_sp, const ModuleSP &objc_module_sp)
 432     : m_process_wp(), m_trampoline_header(LLDB_INVALID_ADDRESS),
 433       m_trampolines_changed_bp_id(LLDB_INVALID_BREAK_ID),
 434       m_objc_module_sp(objc_module_sp) {
 435   if (process_sp)
 436     m_process_wp = process_sp;
 437 }
 438
 439 AppleObjCTrampolineHandler::AppleObjCVTables::~AppleObjCVTables() {
 440   ProcessSP process_sp = GetProcessSP();
 441   if (process_sp) {
 442     if (m_trampolines_changed_bp_id != LLDB_INVALID_BREAK_ID)
 443       process_sp->GetTarget().RemoveBreakpointByID(m_trampolines_changed_bp_id);
 444   }
 445 }
 446
 447 bool AppleObjCTrampolineHandler::AppleObjCVTables::InitializeVTableSymbols() {
 448   if (m_trampoline_header != LLDB_INVALID_ADDRESS)
 449     return true;
 450
 451   ProcessSP process_sp = GetProcessSP();
 452   if (process_sp) {
 453     Target &target = process_sp->GetTarget();
 454
 455     const ModuleList &target_modules = target.GetImages();
 456     std::lock_guard<std::recursive_mutex> guard(target_modules.GetMutex());
 457     size_t num_modules = target_modules.GetSize();
 458     if (!m_objc_module_sp) {
 459       for (size_t i = 0; i < num_modules; i++) {
 460         if (ObjCLanguageRuntime::Get(*process_sp)
 461                 ->IsModuleObjCLibrary(
 462                     target_modules.GetModuleAtIndexUnlocked(i))) {
 463           m_objc_module_sp = target_modules.GetModuleAtIndexUnlocked(i);
 464           break;
 465         }
 466       }
 467     }
 468
 469     if (m_objc_module_sp) {
 470       ConstString trampoline_name("gdb_objc_trampolines");
 471       const Symbol *trampoline_symbol =
 472           m_objc_module_sp->FindFirstSymbolWithNameAndType(trampoline_name,
 473                                                            eSymbolTypeData);
 474       if (trampoline_symbol != nullptr) {
 475         m_trampoline_header = trampoline_symbol->GetLoadAddress(&target);
 476         if (m_trampoline_header == LLDB_INVALID_ADDRESS)
 477           return false;
 478
 479         // Next look up the "changed" symbol and set a breakpoint on that...
 480         ConstString changed_name("gdb_objc_trampolines_changed");
 481         const Symbol *changed_symbol =
 482             m_objc_module_sp->FindFirstSymbolWithNameAndType(changed_name,
 483                                                              eSymbolTypeCode);
 484         if (changed_symbol != nullptr) {
 485           const Address changed_symbol_addr = changed_symbol->GetAddress();
 486           if (!changed_symbol_addr.IsValid())
 487             return false;
 488
 489           lldb::addr_t changed_addr =
 490               changed_symbol_addr.GetOpcodeLoadAddress(&target);
 491           if (changed_addr != LLDB_INVALID_ADDRESS) {
 492             BreakpointSP trampolines_changed_bp_sp =
 493                 target.CreateBreakpoint(changed_addr, true, false);
 494             if (trampolines_changed_bp_sp) {
 495               m_trampolines_changed_bp_id = trampolines_changed_bp_sp->GetID();
 496               trampolines_changed_bp_sp->SetCallback(RefreshTrampolines, this,
 497                                                      true);
 498               trampolines_changed_bp_sp->SetBreakpointKind(
 499                   "objc-trampolines-changed");
 500               return true;
 501             }
 502           }
 503         }
 504       }
 505     }
 506   }
 507   return false;
 508 }
 509
 510 bool AppleObjCTrampolineHandler::AppleObjCVTables::RefreshTrampolines(
 511     void *baton, StoppointCallbackContext *context, lldb::user_id_t break_id,
 512     lldb::user_id_t break_loc_id) {
 513   AppleObjCVTables *vtable_handler = (AppleObjCVTables *)baton;
 514   if (vtable_handler->InitializeVTableSymbols()) {
 515     // The Update function is called with the address of an added region.  So we
 516     // grab that address, and
 517     // feed it into ReadRegions.  Of course, our friend the ABI will get the
 518     // values for us.
 519     ExecutionContext exe_ctx(context->exe_ctx_ref);
 520     Process *process = exe_ctx.GetProcessPtr();
 521     const ABI *abi = process->GetABI().get();
 522
 523     TypeSystemClang *clang_ast_context =
 524         TypeSystemClang::GetScratch(process->GetTarget());
 525     if (!clang_ast_context)
 526       return false;
 527
 528     ValueList argument_values;
 529     Value input_value;
 530     CompilerType clang_void_ptr_type =
 531         clang_ast_context->GetBasicType(eBasicTypeVoid).GetPointerType();
 532
 533     input_value.SetValueType(Value::eValueTypeScalar);
 534     // input_value.SetContext (Value::eContextTypeClangType,
 535     // clang_void_ptr_type);
 536     input_value.SetCompilerType(clang_void_ptr_type);
 537     argument_values.PushValue(input_value);
 538
 539     bool success =
 540         abi->GetArgumentValues(exe_ctx.GetThreadRef(), argument_values);
 541     if (!success)
 542       return false;
 543
 544     // Now get a pointer value from the zeroth argument.
 545     Status error;
 546     DataExtractor data;
 547     error = argument_values.GetValueAtIndex(0)->GetValueAsData(&exe_ctx, data,
 548                                                                nullptr);
 549     lldb::offset_t offset = 0;
 550     lldb::addr_t region_addr = data.GetAddress(&offset);
 551
 552     if (region_addr != 0)
 553       vtable_handler->ReadRegions(region_addr);
 554   }
 555   return false;
 556 }
 557
 558 bool AppleObjCTrampolineHandler::AppleObjCVTables::ReadRegions() {
 559   // The no argument version reads the  start region from the value of
 560   // the gdb_regions_header, and gets started from there.
 561
 562   m_regions.clear();
 563   if (!InitializeVTableSymbols())
 564     return false;
 565   Status error;
 566   ProcessSP process_sp = GetProcessSP();
 567   if (process_sp) {
 568     lldb::addr_t region_addr =
 569         process_sp->ReadPointerFromMemory(m_trampoline_header, error);
 570     if (error.Success())
 571       return ReadRegions(region_addr);
 572   }
 573   return false;
 574 }
 575
 576 bool AppleObjCTrampolineHandler::AppleObjCVTables::ReadRegions(
 577     lldb::addr_t region_addr) {
 578   ProcessSP process_sp = GetProcessSP();
 579   if (!process_sp)
 580     return false;
 581
 582   Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP));
 583
 584   // We aren't starting at the trampoline symbol.
 585   InitializeVTableSymbols();
 586   lldb::addr_t next_region = region_addr;
 587
 588   // Read in the sizes of the headers.
 589   while (next_region != 0) {
 590     m_regions.push_back(VTableRegion(this, next_region));
 591     if (!m_regions.back().IsValid()) {
 592       m_regions.clear();
 593       return false;
 594     }
 595     if (log) {
 596       StreamString s;
 597       m_regions.back().Dump(s);
 598       LLDB_LOGF(log, "Read vtable region: \n%s", s.GetData());
 599     }
 600
 601     next_region = m_regions.back().GetNextRegionAddr();
 602   }
 603
 604   return true;
 605 }
 606
 607 bool AppleObjCTrampolineHandler::AppleObjCVTables::IsAddressInVTables(
 608     lldb::addr_t addr, uint32_t &flags) {
 609   region_collection::iterator pos, end = m_regions.end();
 610   for (pos = m_regions.begin(); pos != end; pos++) {
 611     if ((*pos).AddressInRegion(addr, flags))
 612       return true;
 613   }
 614   return false;
 615 }
 616
 617 const AppleObjCTrampolineHandler::DispatchFunction
 618     AppleObjCTrampolineHandler::g_dispatch_functions[] = {
 619         // NAME                              STRET  SUPER  SUPER2  FIXUP TYPE
 620         {"objc_msgSend", false, false, false, DispatchFunction::eFixUpNone},
 621         {"objc_msgSend_fixup", false, false, false,
 622          DispatchFunction::eFixUpToFix},
 623         {"objc_msgSend_fixedup", false, false, false,
 624          DispatchFunction::eFixUpFixed},
 625         {"objc_msgSend_stret", true, false, false,
 626          DispatchFunction::eFixUpNone},
 627         {"objc_msgSend_stret_fixup", true, false, false,
 628          DispatchFunction::eFixUpToFix},
 629         {"objc_msgSend_stret_fixedup", true, false, false,
 630          DispatchFunction::eFixUpFixed},
 631         {"objc_msgSend_fpret", false, false, false,
 632          DispatchFunction::eFixUpNone},
 633         {"objc_msgSend_fpret_fixup", false, false, false,
 634          DispatchFunction::eFixUpToFix},
 635         {"objc_msgSend_fpret_fixedup", false, false, false,
 636          DispatchFunction::eFixUpFixed},
 637         {"objc_msgSend_fp2ret", false, false, true,
 638          DispatchFunction::eFixUpNone},
 639         {"objc_msgSend_fp2ret_fixup", false, false, true,
 640          DispatchFunction::eFixUpToFix},
 641         {"objc_msgSend_fp2ret_fixedup", false, false, true,
 642          DispatchFunction::eFixUpFixed},
 643         {"objc_msgSendSuper", false, true, false, DispatchFunction::eFixUpNone},
 644         {"objc_msgSendSuper_stret", true, true, false,
 645          DispatchFunction::eFixUpNone},
 646         {"objc_msgSendSuper2", false, true, true, DispatchFunction::eFixUpNone},
 647         {"objc_msgSendSuper2_fixup", false, true, true,
 648          DispatchFunction::eFixUpToFix},
 649         {"objc_msgSendSuper2_fixedup", false, true, true,
 650          DispatchFunction::eFixUpFixed},
 651         {"objc_msgSendSuper2_stret", true, true, true,
 652          DispatchFunction::eFixUpNone},
 653         {"objc_msgSendSuper2_stret_fixup", true, true, true,
 654          DispatchFunction::eFixUpToFix},
 655         {"objc_msgSendSuper2_stret_fixedup", true, true, true,
 656          DispatchFunction::eFixUpFixed},
 657 };
 658
 659 // This is the table of ObjC "accelerated dispatch" functions.  They are a set
 660 // of objc methods that are "seldom overridden" and so the compiler replaces the
 661 // objc_msgSend with a call to one of the dispatch functions.  That will check
 662 // whether the method has been overridden, and directly call the Foundation
 663 // implementation if not.
 664 // This table is supposed to be complete.  If ones get added in the future, we
 665 // will have to add them to the table.
 666 const char *AppleObjCTrampolineHandler::g_opt_dispatch_names[] = {
 667     "objc_alloc",
 668     "objc_autorelease",
 669     "objc_release",
 670     "objc_retain",
 671     "objc_alloc_init",
 672     "objc_allocWithZone",
 673     "objc_opt_class",
 674     "objc_opt_isKindOfClass",
 675     "objc_opt_new",
 676     "objc_opt_respondsToSelector",
 677     "objc_opt_self",
 678 };
 679
 680 AppleObjCTrampolineHandler::AppleObjCTrampolineHandler(
 681     const ProcessSP &process_sp, const ModuleSP &objc_module_sp)
 682     : m_process_wp(), m_objc_module_sp(objc_module_sp),
 683       m_lookup_implementation_function_code(nullptr),
 684       m_impl_fn_addr(LLDB_INVALID_ADDRESS),
 685       m_impl_stret_fn_addr(LLDB_INVALID_ADDRESS),
 686       m_msg_forward_addr(LLDB_INVALID_ADDRESS) {
 687   if (process_sp)
 688     m_process_wp = process_sp;
 689   // Look up the known resolution functions:
 690
 691   ConstString get_impl_name("class_getMethodImplementation");
 692   ConstString get_impl_stret_name("class_getMethodImplementation_stret");
 693   ConstString msg_forward_name("_objc_msgForward");
 694   ConstString msg_forward_stret_name("_objc_msgForward_stret");
 695
 696   Target *target = process_sp ? &process_sp->GetTarget() : nullptr;
 697   const Symbol *class_getMethodImplementation =
 698       m_objc_module_sp->FindFirstSymbolWithNameAndType(get_impl_name,
 699                                                        eSymbolTypeCode);
 700   const Symbol *class_getMethodImplementation_stret =
 701       m_objc_module_sp->FindFirstSymbolWithNameAndType(get_impl_stret_name,
 702                                                        eSymbolTypeCode);
 703   const Symbol *msg_forward = m_objc_module_sp->FindFirstSymbolWithNameAndType(
 704       msg_forward_name, eSymbolTypeCode);
 705   const Symbol *msg_forward_stret =
 706       m_objc_module_sp->FindFirstSymbolWithNameAndType(msg_forward_stret_name,
 707                                                        eSymbolTypeCode);
 708
 709   if (class_getMethodImplementation)
 710     m_impl_fn_addr =
 711         class_getMethodImplementation->GetAddress().GetOpcodeLoadAddress(
 712             target);
 713   if (class_getMethodImplementation_stret)
 714     m_impl_stret_fn_addr =
 715         class_getMethodImplementation_stret->GetAddress().GetOpcodeLoadAddress(
 716             target);
 717   if (msg_forward)
 718     m_msg_forward_addr = msg_forward->GetAddress().GetOpcodeLoadAddress(target);
 719   if (msg_forward_stret)
 720     m_msg_forward_stret_addr =
 721         msg_forward_stret->GetAddress().GetOpcodeLoadAddress(target);
 722
 723   // FIXME: Do some kind of logging here.
 724   if (m_impl_fn_addr == LLDB_INVALID_ADDRESS) {
 725     // If we can't even find the ordinary get method implementation function,
 726     // then we aren't going to be able to
 727     // step through any method dispatches.  Warn to that effect and get out of
 728     // here.
 729     if (process_sp->CanJIT()) {
 730       process_sp->GetTarget().GetDebugger().GetErrorStream().Printf(
 731           "Could not find implementation lookup function \"%s\""
 732           " step in through ObjC method dispatch will not work.\n",
 733           get_impl_name.AsCString());
 734     }
 735     return;
 736   } else if (m_impl_stret_fn_addr == LLDB_INVALID_ADDRESS) {
 737     // It there is no stret return lookup function, assume that it is the same
 738     // as the straight lookup:
 739     m_impl_stret_fn_addr = m_impl_fn_addr;
 740     // Also we will use the version of the lookup code that doesn't rely on the
 741     // stret version of the function.
 742     m_lookup_implementation_function_code =
 743         g_lookup_implementation_no_stret_function_code;
 744   } else {
 745     m_lookup_implementation_function_code =
 746         g_lookup_implementation_with_stret_function_code;
 747   }
 748
 749   // Look up the addresses for the objc dispatch functions and cache
 750   // them.  For now I'm inspecting the symbol names dynamically to
 751   // figure out how to dispatch to them.  If it becomes more
 752   // complicated than this we can turn the g_dispatch_functions char *
 753   // array into a template table, and populate the DispatchFunction
 754   // map from there.
 755
 756   for (size_t i = 0; i != llvm::array_lengthof(g_dispatch_functions); i++) {
 757     ConstString name_const_str(g_dispatch_functions[i].name);
 758     const Symbol *msgSend_symbol =
 759         m_objc_module_sp->FindFirstSymbolWithNameAndType(name_const_str,
 760                                                          eSymbolTypeCode);
 761     if (msgSend_symbol && msgSend_symbol->ValueIsAddress()) {
 762       // FIXME: Make g_dispatch_functions static table of
 763       // DispatchFunctions, and have the map be address->index.
 764       // Problem is we also need to lookup the dispatch function.  For
 765       // now we could have a side table of stret & non-stret dispatch
 766       // functions.  If that's as complex as it gets, we're fine.
 767
 768       lldb::addr_t sym_addr =
 769           msgSend_symbol->GetAddressRef().GetOpcodeLoadAddress(target);
 770
 771       m_msgSend_map.insert(std::pair<lldb::addr_t, int>(sym_addr, i));
 772     }
 773   }
 774
 775   // Similarly, cache the addresses of the "optimized dispatch" function.
 776   for (size_t i = 0; i != llvm::array_lengthof(g_opt_dispatch_names); i++) {
 777     ConstString name_const_str(g_opt_dispatch_names[i]);
 778     const Symbol *msgSend_symbol =
 779         m_objc_module_sp->FindFirstSymbolWithNameAndType(name_const_str,
 780                                                          eSymbolTypeCode);
 781     if (msgSend_symbol && msgSend_symbol->ValueIsAddress()) {
 782       lldb::addr_t sym_addr =
 783           msgSend_symbol->GetAddressRef().GetOpcodeLoadAddress(target);
 784
 785       m_opt_dispatch_map.emplace(sym_addr, i);
 786     }
 787   }
 788
 789   // Build our vtable dispatch handler here:
 790   m_vtables_up =
 791       std::make_unique<AppleObjCVTables>(process_sp, m_objc_module_sp);
 792   if (m_vtables_up)
 793     m_vtables_up->ReadRegions();
 794 }
 795
 796 lldb::addr_t
 797 AppleObjCTrampolineHandler::SetupDispatchFunction(Thread &thread,
 798                                                   ValueList &dispatch_values) {
 799   ThreadSP thread_sp(thread.shared_from_this());
 800   ExecutionContext exe_ctx(thread_sp);
 801   DiagnosticManager diagnostics;
 802   Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP));
 803
 804   lldb::addr_t args_addr = LLDB_INVALID_ADDRESS;
 805   FunctionCaller *impl_function_caller = nullptr;
 806
 807   // Scope for mutex locker:
 808   {
 809     std::lock_guard<std::mutex> guard(m_impl_function_mutex);
 810
 811     // First stage is to make the ClangUtility to hold our injected function:
 812
 813     if (!m_impl_code) {
 814       if (m_lookup_implementation_function_code != nullptr) {
 815         Status error;
 816         m_impl_code.reset(exe_ctx.GetTargetRef().GetUtilityFunctionForLanguage(
 817             m_lookup_implementation_function_code, eLanguageTypeObjC,
 818             g_lookup_implementation_function_name, error));
 819         if (error.Fail()) {
 820           LLDB_LOGF(
 821               log,
 822               "Failed to get Utility Function for implementation lookup: %s.",
 823               error.AsCString());
 824           m_impl_code.reset();
 825           return args_addr;
 826         }
 827
 828         if (!m_impl_code->Install(diagnostics, exe_ctx)) {
 829           if (log) {
 830             LLDB_LOGF(log, "Failed to install implementation lookup.");
 831             diagnostics.Dump(log);
 832           }
 833           m_impl_code.reset();
 834           return args_addr;
 835         }
 836       } else {
 837         LLDB_LOGF(log, "No method lookup implementation code.");
 838         return LLDB_INVALID_ADDRESS;
 839       }
 840
 841       // Next make the runner function for our implementation utility function.
 842       TypeSystemClang *clang_ast_context =
 843           TypeSystemClang::GetScratch(thread.GetProcess()->GetTarget());
 844       if (!clang_ast_context)
 845         return LLDB_INVALID_ADDRESS;
 846
 847       CompilerType clang_void_ptr_type =
 848           clang_ast_context->GetBasicType(eBasicTypeVoid).GetPointerType();
 849       Status error;
 850
 851       impl_function_caller = m_impl_code->MakeFunctionCaller(
 852           clang_void_ptr_type, dispatch_values, thread_sp, error);
 853       if (error.Fail()) {
 854         LLDB_LOGF(log,
 855                   "Error getting function caller for dispatch lookup: \"%s\".",
 856                   error.AsCString());
 857         return args_addr;
 858       }
 859     } else {
 860       impl_function_caller = m_impl_code->GetFunctionCaller();
 861     }
 862   }
 863
 864   diagnostics.Clear();
 865
 866   // Now write down the argument values for this particular call.
 867   // This looks like it might be a race condition if other threads
 868   // were calling into here, but actually it isn't because we allocate
 869   // a new args structure for this call by passing args_addr =
 870   // LLDB_INVALID_ADDRESS...
 871
 872   if (!impl_function_caller->WriteFunctionArguments(
 873           exe_ctx, args_addr, dispatch_values, diagnostics)) {
 874     if (log) {
 875       LLDB_LOGF(log, "Error writing function arguments.");
 876       diagnostics.Dump(log);
 877     }
 878     return args_addr;
 879   }
 880
 881   return args_addr;
 882 }
 883
 884 const AppleObjCTrampolineHandler::DispatchFunction *
 885 AppleObjCTrampolineHandler::FindDispatchFunction(lldb::addr_t addr) {
 886   MsgsendMap::iterator pos;
 887   pos = m_msgSend_map.find(addr);
 888   if (pos != m_msgSend_map.end()) {
 889     return &g_dispatch_functions[(*pos).second];
 890   }
 891   return nullptr;
 892 }
 893
 894 void
 895 AppleObjCTrampolineHandler::ForEachDispatchFunction(
 896     std::function<void(lldb::addr_t,
 897                        const DispatchFunction &)> callback) {
 898   for (auto elem : m_msgSend_map) {
 899     callback(elem.first, g_dispatch_functions[elem.second]);
 900   }
 901 }
 902
 903 ThreadPlanSP
 904 AppleObjCTrampolineHandler::GetStepThroughDispatchPlan(Thread &thread,
 905                                                        bool stop_others) {
 906   ThreadPlanSP ret_plan_sp;
 907   lldb::addr_t curr_pc = thread.GetRegisterContext()->GetPC();
 908
 909   DispatchFunction vtable_dispatch
 910       = {"vtable", 0, false, false, DispatchFunction::eFixUpFixed};
 911
 912   // First step is to look and see if we are in one of the known ObjC
 913   // dispatch functions.  We've already compiled a table of same, so
 914   // consult it.
 915
 916   const DispatchFunction *this_dispatch = FindDispatchFunction(curr_pc);
 917
 918   // Next check to see if we are in a vtable region:
 919
 920   if (!this_dispatch && m_vtables_up) {
 921     uint32_t flags;
 922     if (m_vtables_up->IsAddressInVTables(curr_pc, flags)) {
 923       vtable_dispatch.stret_return =
 924           (flags & AppleObjCVTables::eOBJC_TRAMPOLINE_STRET) ==
 925           AppleObjCVTables::eOBJC_TRAMPOLINE_STRET;
 926       this_dispatch = &vtable_dispatch;
 927     }
 928   }
 929
 930   if (this_dispatch) {
 931     Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP));
 932
 933     // We are decoding a method dispatch.  First job is to pull the
 934     // arguments out:
 935
 936     lldb::StackFrameSP thread_cur_frame = thread.GetStackFrameAtIndex(0);
 937
 938     const ABI *abi = nullptr;
 939     ProcessSP process_sp(thread.CalculateProcess());
 940     if (process_sp)
 941       abi = process_sp->GetABI().get();
 942     if (abi == nullptr)
 943       return ret_plan_sp;
 944
 945     TargetSP target_sp(thread.CalculateTarget());
 946
 947     TypeSystemClang *clang_ast_context = TypeSystemClang::GetScratch(*target_sp);
 948     if (!clang_ast_context)
 949       return ret_plan_sp;
 950
 951     ValueList argument_values;
 952     Value void_ptr_value;
 953     CompilerType clang_void_ptr_type =
 954         clang_ast_context->GetBasicType(eBasicTypeVoid).GetPointerType();
 955     void_ptr_value.SetValueType(Value::eValueTypeScalar);
 956     // void_ptr_value.SetContext (Value::eContextTypeClangType,
 957     // clang_void_ptr_type);
 958     void_ptr_value.SetCompilerType(clang_void_ptr_type);
 959
 960     int obj_index;
 961     int sel_index;
 962
 963     // If this is a struct return dispatch, then the first argument is
 964     // the return struct pointer, and the object is the second, and
 965     // the selector is the third.  Otherwise the object is the first
 966     // and the selector the second.
 967     if (this_dispatch->stret_return) {
 968       obj_index = 1;
 969       sel_index = 2;
 970       argument_values.PushValue(void_ptr_value);
 971       argument_values.PushValue(void_ptr_value);
 972       argument_values.PushValue(void_ptr_value);
 973     } else {
 974       obj_index = 0;
 975       sel_index = 1;
 976       argument_values.PushValue(void_ptr_value);
 977       argument_values.PushValue(void_ptr_value);
 978     }
 979
 980     bool success = abi->GetArgumentValues(thread, argument_values);
 981     if (!success)
 982       return ret_plan_sp;
 983
 984     lldb::addr_t obj_addr =
 985         argument_values.GetValueAtIndex(obj_index)->GetScalar().ULongLong();
 986     if (obj_addr == 0x0) {
 987       LLDB_LOGF(
 988           log,
 989           "Asked to step to dispatch to nil object, returning empty plan.");
 990       return ret_plan_sp;
 991     }
 992
 993     ExecutionContext exe_ctx(thread.shared_from_this());
 994     Process *process = exe_ctx.GetProcessPtr();
 995     // isa_addr will store the class pointer that the method is being
 996     // dispatched to - so either the class directly or the super class
 997     // if this is one of the objc_msgSendSuper flavors.  That's mostly
 998     // used to look up the class/selector pair in our cache.
 999
1000     lldb::addr_t isa_addr = LLDB_INVALID_ADDRESS;
1001     lldb::addr_t sel_addr =
1002         argument_values.GetValueAtIndex(sel_index)->GetScalar().ULongLong();
1003
1004     // Figure out the class this is being dispatched to and see if
1005     // we've already cached this method call, If so we can push a
1006     // run-to-address plan directly.  Otherwise we have to figure out
1007     // where the implementation lives.
1008
1009     if (this_dispatch->is_super) {
1010       if (this_dispatch->is_super2) {
1011         // In the objc_msgSendSuper2 case, we don't get the object
1012         // directly, we get a structure containing the object and the
1013         // class to which the super message is being sent.  So we need
1014         // to dig the super out of the class and use that.
1015
1016         Value super_value(*(argument_values.GetValueAtIndex(obj_index)));
1017         super_value.GetScalar() += process->GetAddressByteSize();
1018         super_value.ResolveValue(&exe_ctx);
1019
1020         if (super_value.GetScalar().IsValid()) {
1021
1022           // isa_value now holds the class pointer.  The second word of the
1023           // class pointer is the super-class pointer:
1024           super_value.GetScalar() += process->GetAddressByteSize();
1025           super_value.ResolveValue(&exe_ctx);
1026           if (super_value.GetScalar().IsValid())
1027             isa_addr = super_value.GetScalar().ULongLong();
1028           else {
1029             LLDB_LOGF(log, "Failed to extract the super class value from the "
1030                            "class in objc_super.");
1031           }
1032         } else {
1033           LLDB_LOGF(log, "Failed to extract the class value from objc_super.");
1034         }
1035       } else {
1036         // In the objc_msgSendSuper case, we don't get the object
1037         // directly, we get a two element structure containing the
1038         // object and the super class to which the super message is
1039         // being sent.  So the class we want is the second element of
1040         // this structure.
1041
1042         Value super_value(*(argument_values.GetValueAtIndex(obj_index)));
1043         super_value.GetScalar() += process->GetAddressByteSize();
1044         super_value.ResolveValue(&exe_ctx);
1045
1046         if (super_value.GetScalar().IsValid()) {
1047           isa_addr = super_value.GetScalar().ULongLong();
1048         } else {
1049           LLDB_LOGF(log, "Failed to extract the class value from objc_super.");
1050         }
1051       }
1052     } else {
1053       // In the direct dispatch case, the object->isa is the class pointer we
1054       // want.
1055
1056       // This is a little cheesy, but since object->isa is the first field,
1057       // making the object value a load address value and resolving it will get
1058       // the pointer sized data pointed to by that value...
1059
1060       // Note, it isn't a fatal error not to be able to get the
1061       // address from the object, since this might be a "tagged
1062       // pointer" which isn't a real object, but rather some word
1063       // length encoded dingus.
1064
1065       Value isa_value(*(argument_values.GetValueAtIndex(obj_index)));
1066
1067       isa_value.SetValueType(Value::eValueTypeLoadAddress);
1068       isa_value.ResolveValue(&exe_ctx);
1069       if (isa_value.GetScalar().IsValid()) {
1070         isa_addr = isa_value.GetScalar().ULongLong();
1071       } else {
1072         LLDB_LOGF(log, "Failed to extract the isa value from object.");
1073       }
1074     }
1075
1076     // Okay, we've got the address of the class for which we're resolving this,
1077     // let's see if it's in our cache:
1078     lldb::addr_t impl_addr = LLDB_INVALID_ADDRESS;
1079
1080     if (isa_addr != LLDB_INVALID_ADDRESS) {
1081       if (log) {
1082         LLDB_LOGF(log,
1083                   "Resolving call for class - 0x%" PRIx64
1084                   " and selector - 0x%" PRIx64,
1085                   isa_addr, sel_addr);
1086       }
1087       ObjCLanguageRuntime *objc_runtime =
1088           ObjCLanguageRuntime::Get(*thread.GetProcess());
1089       assert(objc_runtime != nullptr);
1090
1091       impl_addr = objc_runtime->LookupInMethodCache(isa_addr, sel_addr);
1092     }
1093
1094     if (impl_addr != LLDB_INVALID_ADDRESS) {
1095       // Yup, it was in the cache, so we can run to that address directly.
1096
1097       LLDB_LOGF(log, "Found implementation address in cache: 0x%" PRIx64,
1098                 impl_addr);
1099
1100       ret_plan_sp = std::make_shared<ThreadPlanRunToAddress>(thread, impl_addr,
1101                                                              stop_others);
1102     } else {
1103       // We haven't seen this class/selector pair yet.  Look it up.
1104       StreamString errors;
1105       Address impl_code_address;
1106
1107       ValueList dispatch_values;
1108
1109       // We've will inject a little function in the target that takes the
1110       // object, selector and some flags,
1111       // and figures out the implementation.  Looks like:
1112       //      void *__lldb_objc_find_implementation_for_selector (void *object,
1113       //                                                          void *sel,
1114       //                                                          int is_stret,
1115       //                                                          int is_super,
1116       //                                                          int is_super2,
1117       //                                                          int is_fixup,
1118       //                                                          int is_fixed,
1119       //                                                          int debug)
1120       // So set up the arguments for that call.
1121
1122       dispatch_values.PushValue(*(argument_values.GetValueAtIndex(obj_index)));
1123       dispatch_values.PushValue(*(argument_values.GetValueAtIndex(sel_index)));
1124
1125       Value flag_value;
1126       CompilerType clang_int_type =
1127           clang_ast_context->GetBuiltinTypeForEncodingAndBitSize(
1128               lldb::eEncodingSint, 32);
1129       flag_value.SetValueType(Value::eValueTypeScalar);
1130       // flag_value.SetContext (Value::eContextTypeClangType, clang_int_type);
1131       flag_value.SetCompilerType(clang_int_type);
1132
1133       if (this_dispatch->stret_return)
1134         flag_value.GetScalar() = 1;
1135       else
1136         flag_value.GetScalar() = 0;
1137       dispatch_values.PushValue(flag_value);
1138
1139       if (this_dispatch->is_super)
1140         flag_value.GetScalar() = 1;
1141       else
1142         flag_value.GetScalar() = 0;
1143       dispatch_values.PushValue(flag_value);
1144
1145       if (this_dispatch->is_super2)
1146         flag_value.GetScalar() = 1;
1147       else
1148         flag_value.GetScalar() = 0;
1149       dispatch_values.PushValue(flag_value);
1150
1151       switch (this_dispatch->fixedup) {
1152       case DispatchFunction::eFixUpNone:
1153         flag_value.GetScalar() = 0;
1154         dispatch_values.PushValue(flag_value);
1155         dispatch_values.PushValue(flag_value);
1156         break;
1157       case DispatchFunction::eFixUpFixed:
1158         flag_value.GetScalar() = 1;
1159         dispatch_values.PushValue(flag_value);
1160         flag_value.GetScalar() = 1;
1161         dispatch_values.PushValue(flag_value);
1162         break;
1163       case DispatchFunction::eFixUpToFix:
1164         flag_value.GetScalar() = 1;
1165         dispatch_values.PushValue(flag_value);
1166         flag_value.GetScalar() = 0;
1167         dispatch_values.PushValue(flag_value);
1168         break;
1169       }
1170       if (log && log->GetVerbose())
1171         flag_value.GetScalar() = 1;
1172       else
1173         flag_value.GetScalar() = 0; // FIXME - Set to 0 when debugging is done.
1174       dispatch_values.PushValue(flag_value);
1175
1176       // The step through code might have to fill in the cache, so it
1177       // is not safe to run only one thread.  So we override the
1178       // stop_others value passed in to us here:
1179       const bool trampoline_stop_others = false;
1180       ret_plan_sp = std::make_shared<AppleThreadPlanStepThroughObjCTrampoline>(
1181           thread, *this, dispatch_values, isa_addr, sel_addr,
1182           trampoline_stop_others);
1183       if (log) {
1184         StreamString s;
1185         ret_plan_sp->GetDescription(&s, eDescriptionLevelFull);
1186         LLDB_LOGF(log, "Using ObjC step plan: %s.\n", s.GetData());
1187       }
1188     }
1189   }
1190
1191   // Finally, check if we have hit an "optimized dispatch" function.  This will
1192   // either directly call the base implementation or dispatch an objc_msgSend
1193   // if the method has been overridden.  So we just do a "step in/step out",
1194   // setting a breakpoint on objc_msgSend, and if we hit the msgSend, we
1195   // will automatically step in again.  That's the job of the
1196   // AppleThreadPlanStepThroughDirectDispatch.
1197   if (!this_dispatch && !ret_plan_sp) {
1198     MsgsendMap::iterator pos;
1199     pos = m_opt_dispatch_map.find(curr_pc);
1200     if (pos != m_opt_dispatch_map.end()) {
1201
1202       const char *opt_name = g_opt_dispatch_names[(*pos).second];
1203
1204       bool trampoline_stop_others = false;
1205       LazyBool step_in_should_stop = eLazyBoolCalculate;
1206       ret_plan_sp = std::make_shared<AppleThreadPlanStepThroughDirectDispatch> (
1207           thread, *this, opt_name, trampoline_stop_others, step_in_should_stop);
1208     }
1209   }
1210
1211   return ret_plan_sp;
1212 }
1213
1214 FunctionCaller *
1215 AppleObjCTrampolineHandler::GetLookupImplementationFunctionCaller() {
1216   return m_impl_code->GetFunctionCaller();
1217 }