1 //===-- IRForTarget.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 "IRForTarget.h" 10 11 #include "ClangExpressionDeclMap.h" 12 #include "ClangUtil.h" 13 14 #include "Plugins/TypeSystem/Clang/TypeSystemClang.h" 15 #include "llvm/IR/Constants.h" 16 #include "llvm/IR/DataLayout.h" 17 #include "llvm/IR/Operator.h" 18 #include "llvm/IR/InstrTypes.h" 19 #include "llvm/IR/Instructions.h" 20 #include "llvm/IR/Intrinsics.h" 21 #include "llvm/IR/LegacyPassManager.h" 22 #include "llvm/IR/Metadata.h" 23 #include "llvm/IR/Module.h" 24 #include "llvm/IR/ValueSymbolTable.h" 25 #include "llvm/Support/raw_ostream.h" 26 #include "llvm/Transforms/IPO.h" 27 28 #include "clang/AST/ASTContext.h" 29 30 #include "lldb/Core/dwarf.h" 31 #include "lldb/Expression/IRExecutionUnit.h" 32 #include "lldb/Expression/IRInterpreter.h" 33 #include "lldb/Symbol/CompilerType.h" 34 #include "lldb/Utility/ConstString.h" 35 #include "lldb/Utility/DataBufferHeap.h" 36 #include "lldb/Utility/Endian.h" 37 #include "lldb/Utility/LLDBLog.h" 38 #include "lldb/Utility/Log.h" 39 #include "lldb/Utility/Scalar.h" 40 #include "lldb/Utility/StreamString.h" 41 42 #include <map> 43 44 using namespace llvm; 45 using lldb_private::LLDBLog; 46 47 typedef SmallVector<Instruction *, 2> InstrList; 48 49 IRForTarget::FunctionValueCache::FunctionValueCache(Maker const &maker) 50 : m_maker(maker), m_values() {} 51 52 IRForTarget::FunctionValueCache::~FunctionValueCache() = default; 53 54 llvm::Value * 55 IRForTarget::FunctionValueCache::GetValue(llvm::Function *function) { 56 if (!m_values.count(function)) { 57 llvm::Value *ret = m_maker(function); 58 m_values[function] = ret; 59 return ret; 60 } 61 return m_values[function]; 62 } 63 64 static llvm::Value *FindEntryInstruction(llvm::Function *function) { 65 if (function->empty()) 66 return nullptr; 67 68 return function->getEntryBlock().getFirstNonPHIOrDbg(); 69 } 70 71 IRForTarget::IRForTarget(lldb_private::ClangExpressionDeclMap *decl_map, 72 bool resolve_vars, 73 lldb_private::IRExecutionUnit &execution_unit, 74 lldb_private::Stream &error_stream, 75 const char *func_name) 76 : m_resolve_vars(resolve_vars), m_func_name(func_name), 77 m_decl_map(decl_map), m_error_stream(error_stream), 78 m_execution_unit(execution_unit), 79 m_entry_instruction_finder(FindEntryInstruction) {} 80 81 /* Handy utility functions used at several places in the code */ 82 83 static std::string PrintValue(const Value *value, bool truncate = false) { 84 std::string s; 85 if (value) { 86 raw_string_ostream rso(s); 87 value->print(rso); 88 rso.flush(); 89 if (truncate) 90 s.resize(s.length() - 1); 91 } 92 return s; 93 } 94 95 static std::string PrintType(const llvm::Type *type, bool truncate = false) { 96 std::string s; 97 raw_string_ostream rso(s); 98 type->print(rso); 99 rso.flush(); 100 if (truncate) 101 s.resize(s.length() - 1); 102 return s; 103 } 104 105 bool IRForTarget::FixFunctionLinkage(llvm::Function &llvm_function) { 106 llvm_function.setLinkage(GlobalValue::ExternalLinkage); 107 108 return true; 109 } 110 111 clang::NamedDecl *IRForTarget::DeclForGlobal(const GlobalValue *global_val, 112 Module *module) { 113 NamedMDNode *named_metadata = 114 module->getNamedMetadata("clang.global.decl.ptrs"); 115 116 if (!named_metadata) 117 return nullptr; 118 119 unsigned num_nodes = named_metadata->getNumOperands(); 120 unsigned node_index; 121 122 for (node_index = 0; node_index < num_nodes; ++node_index) { 123 llvm::MDNode *metadata_node = 124 dyn_cast<llvm::MDNode>(named_metadata->getOperand(node_index)); 125 if (!metadata_node) 126 return nullptr; 127 128 if (metadata_node->getNumOperands() != 2) 129 continue; 130 131 if (mdconst::dyn_extract_or_null<GlobalValue>( 132 metadata_node->getOperand(0)) != global_val) 133 continue; 134 135 ConstantInt *constant_int = 136 mdconst::dyn_extract<ConstantInt>(metadata_node->getOperand(1)); 137 138 if (!constant_int) 139 return nullptr; 140 141 uintptr_t ptr = constant_int->getZExtValue(); 142 143 return reinterpret_cast<clang::NamedDecl *>(ptr); 144 } 145 146 return nullptr; 147 } 148 149 clang::NamedDecl *IRForTarget::DeclForGlobal(GlobalValue *global_val) { 150 return DeclForGlobal(global_val, m_module); 151 } 152 153 /// Returns true iff the mangled symbol is for a static guard variable. 154 static bool isGuardVariableSymbol(llvm::StringRef mangled_symbol, 155 bool check_ms_abi = true) { 156 bool result = mangled_symbol.startswith("_ZGV"); // Itanium ABI guard variable 157 if (check_ms_abi) 158 result |= mangled_symbol.endswith("@4IA"); // Microsoft ABI 159 return result; 160 } 161 162 bool IRForTarget::CreateResultVariable(llvm::Function &llvm_function) { 163 lldb_private::Log *log(GetLog(LLDBLog::Expressions)); 164 165 if (!m_resolve_vars) 166 return true; 167 168 // Find the result variable. If it doesn't exist, we can give up right here. 169 170 ValueSymbolTable &value_symbol_table = m_module->getValueSymbolTable(); 171 172 llvm::StringRef result_name; 173 bool found_result = false; 174 175 for (StringMapEntry<llvm::Value *> &value_symbol : value_symbol_table) { 176 result_name = value_symbol.first(); 177 178 // Check if this is a guard variable. It seems this causes some hiccups 179 // on Windows, so let's only check for Itanium guard variables. 180 bool is_guard_var = isGuardVariableSymbol(result_name, /*MS ABI*/ false); 181 182 if (result_name.contains("$__lldb_expr_result_ptr") && !is_guard_var) { 183 found_result = true; 184 m_result_is_pointer = true; 185 break; 186 } 187 188 if (result_name.contains("$__lldb_expr_result") && !is_guard_var) { 189 found_result = true; 190 m_result_is_pointer = false; 191 break; 192 } 193 } 194 195 if (!found_result) { 196 LLDB_LOG(log, "Couldn't find result variable"); 197 198 return true; 199 } 200 201 LLDB_LOG(log, "Result name: \"{0}\"", result_name); 202 203 Value *result_value = m_module->getNamedValue(result_name); 204 205 if (!result_value) { 206 LLDB_LOG(log, "Result variable had no data"); 207 208 m_error_stream.Format("Internal error [IRForTarget]: Result variable's " 209 "name ({0}) exists, but not its definition\n", 210 result_name); 211 212 return false; 213 } 214 215 LLDB_LOG(log, "Found result in the IR: \"{0}\"", 216 PrintValue(result_value, false)); 217 218 GlobalVariable *result_global = dyn_cast<GlobalVariable>(result_value); 219 220 if (!result_global) { 221 LLDB_LOG(log, "Result variable isn't a GlobalVariable"); 222 223 m_error_stream.Format("Internal error [IRForTarget]: Result variable ({0}) " 224 "is defined, but is not a global variable\n", 225 result_name); 226 227 return false; 228 } 229 230 clang::NamedDecl *result_decl = DeclForGlobal(result_global); 231 if (!result_decl) { 232 LLDB_LOG(log, "Result variable doesn't have a corresponding Decl"); 233 234 m_error_stream.Format("Internal error [IRForTarget]: Result variable ({0}) " 235 "does not have a corresponding Clang entity\n", 236 result_name); 237 238 return false; 239 } 240 241 if (log) { 242 std::string decl_desc_str; 243 raw_string_ostream decl_desc_stream(decl_desc_str); 244 result_decl->print(decl_desc_stream); 245 decl_desc_stream.flush(); 246 247 LLDB_LOG(log, "Found result decl: \"{0}\"", decl_desc_str); 248 } 249 250 clang::VarDecl *result_var = dyn_cast<clang::VarDecl>(result_decl); 251 if (!result_var) { 252 LLDB_LOG(log, "Result variable Decl isn't a VarDecl"); 253 254 m_error_stream.Format("Internal error [IRForTarget]: Result variable " 255 "({0})'s corresponding Clang entity isn't a " 256 "variable\n", 257 result_name); 258 259 return false; 260 } 261 262 // Get the next available result name from m_decl_map and create the 263 // persistent variable for it 264 265 // If the result is an Lvalue, it is emitted as a pointer; see 266 // ASTResultSynthesizer::SynthesizeBodyResult. 267 if (m_result_is_pointer) { 268 clang::QualType pointer_qual_type = result_var->getType(); 269 const clang::Type *pointer_type = pointer_qual_type.getTypePtr(); 270 271 const clang::PointerType *pointer_pointertype = 272 pointer_type->getAs<clang::PointerType>(); 273 const clang::ObjCObjectPointerType *pointer_objcobjpointertype = 274 pointer_type->getAs<clang::ObjCObjectPointerType>(); 275 276 if (pointer_pointertype) { 277 clang::QualType element_qual_type = pointer_pointertype->getPointeeType(); 278 279 m_result_type = lldb_private::TypeFromParser( 280 m_decl_map->GetTypeSystem()->GetType(element_qual_type)); 281 } else if (pointer_objcobjpointertype) { 282 clang::QualType element_qual_type = 283 clang::QualType(pointer_objcobjpointertype->getObjectType(), 0); 284 285 m_result_type = lldb_private::TypeFromParser( 286 m_decl_map->GetTypeSystem()->GetType(element_qual_type)); 287 } else { 288 LLDB_LOG(log, "Expected result to have pointer type, but it did not"); 289 290 m_error_stream.Format("Internal error [IRForTarget]: Lvalue result ({0}) " 291 "is not a pointer variable\n", 292 result_name); 293 294 return false; 295 } 296 } else { 297 m_result_type = lldb_private::TypeFromParser( 298 m_decl_map->GetTypeSystem()->GetType(result_var->getType())); 299 } 300 301 lldb::TargetSP target_sp(m_execution_unit.GetTarget()); 302 llvm::Optional<uint64_t> bit_size = m_result_type.GetBitSize(target_sp.get()); 303 if (!bit_size) { 304 lldb_private::StreamString type_desc_stream; 305 m_result_type.DumpTypeDescription(&type_desc_stream); 306 307 LLDB_LOG(log, "Result type has unknown size"); 308 309 m_error_stream.Printf("Error [IRForTarget]: Size of result type '%s' " 310 "couldn't be determined\n", 311 type_desc_stream.GetData()); 312 return false; 313 } 314 315 if (log) { 316 lldb_private::StreamString type_desc_stream; 317 m_result_type.DumpTypeDescription(&type_desc_stream); 318 319 LLDB_LOG(log, "Result decl type: \"{0}\"", type_desc_stream.GetData()); 320 } 321 322 m_result_name = lldb_private::ConstString("$RESULT_NAME"); 323 324 LLDB_LOG(log, "Creating a new result global: \"{0}\" with size {1}", 325 m_result_name, 326 m_result_type.GetByteSize(target_sp.get()).value_or(0)); 327 328 // Construct a new result global and set up its metadata 329 330 GlobalVariable *new_result_global = new GlobalVariable( 331 (*m_module), result_global->getValueType(), false, /* not constant */ 332 GlobalValue::ExternalLinkage, nullptr, /* no initializer */ 333 m_result_name.GetCString()); 334 335 // It's too late in compilation to create a new VarDecl for this, but we 336 // don't need to. We point the metadata at the old VarDecl. This creates an 337 // odd anomaly: a variable with a Value whose name is something like $0 and a 338 // Decl whose name is $__lldb_expr_result. This condition is handled in 339 // ClangExpressionDeclMap::DoMaterialize, and the name of the variable is 340 // fixed up. 341 342 ConstantInt *new_constant_int = 343 ConstantInt::get(llvm::Type::getInt64Ty(m_module->getContext()), 344 reinterpret_cast<uintptr_t>(result_decl), false); 345 346 llvm::Metadata *values[2]; 347 values[0] = ConstantAsMetadata::get(new_result_global); 348 values[1] = ConstantAsMetadata::get(new_constant_int); 349 350 ArrayRef<Metadata *> value_ref(values, 2); 351 352 MDNode *persistent_global_md = MDNode::get(m_module->getContext(), value_ref); 353 NamedMDNode *named_metadata = 354 m_module->getNamedMetadata("clang.global.decl.ptrs"); 355 named_metadata->addOperand(persistent_global_md); 356 357 LLDB_LOG(log, "Replacing \"{0}\" with \"{1}\"", PrintValue(result_global), 358 PrintValue(new_result_global)); 359 360 if (result_global->use_empty()) { 361 // We need to synthesize a store for this variable, because otherwise 362 // there's nothing to put into its equivalent persistent variable. 363 364 BasicBlock &entry_block(llvm_function.getEntryBlock()); 365 Instruction *first_entry_instruction(entry_block.getFirstNonPHIOrDbg()); 366 367 if (!first_entry_instruction) 368 return false; 369 370 if (!result_global->hasInitializer()) { 371 LLDB_LOG(log, "Couldn't find initializer for unused variable"); 372 373 m_error_stream.Format("Internal error [IRForTarget]: Result variable " 374 "({0}) has no writes and no initializer\n", 375 result_name); 376 377 return false; 378 } 379 380 Constant *initializer = result_global->getInitializer(); 381 382 StoreInst *synthesized_store = 383 new StoreInst(initializer, new_result_global, first_entry_instruction); 384 385 LLDB_LOG(log, "Synthesized result store \"{0}\"\n", 386 PrintValue(synthesized_store)); 387 } else { 388 result_global->replaceAllUsesWith(new_result_global); 389 } 390 391 if (!m_decl_map->AddPersistentVariable( 392 result_decl, m_result_name, m_result_type, true, m_result_is_pointer)) 393 return false; 394 395 result_global->eraseFromParent(); 396 397 return true; 398 } 399 400 bool IRForTarget::RewriteObjCConstString(llvm::GlobalVariable *ns_str, 401 llvm::GlobalVariable *cstr) { 402 lldb_private::Log *log(GetLog(LLDBLog::Expressions)); 403 404 Type *ns_str_ty = ns_str->getType(); 405 406 Type *i8_ptr_ty = Type::getInt8PtrTy(m_module->getContext()); 407 Type *i32_ty = Type::getInt32Ty(m_module->getContext()); 408 Type *i8_ty = Type::getInt8Ty(m_module->getContext()); 409 410 if (!m_CFStringCreateWithBytes) { 411 lldb::addr_t CFStringCreateWithBytes_addr; 412 413 static lldb_private::ConstString g_CFStringCreateWithBytes_str( 414 "CFStringCreateWithBytes"); 415 416 bool missing_weak = false; 417 CFStringCreateWithBytes_addr = 418 m_execution_unit.FindSymbol(g_CFStringCreateWithBytes_str, 419 missing_weak); 420 if (CFStringCreateWithBytes_addr == LLDB_INVALID_ADDRESS || missing_weak) { 421 LLDB_LOG(log, "Couldn't find CFStringCreateWithBytes in the target"); 422 423 m_error_stream.Printf("Error [IRForTarget]: Rewriting an Objective-C " 424 "constant string requires " 425 "CFStringCreateWithBytes\n"); 426 427 return false; 428 } 429 430 LLDB_LOG(log, "Found CFStringCreateWithBytes at {0}", 431 CFStringCreateWithBytes_addr); 432 433 // Build the function type: 434 // 435 // CFStringRef CFStringCreateWithBytes ( 436 // CFAllocatorRef alloc, 437 // const UInt8 *bytes, 438 // CFIndex numBytes, 439 // CFStringEncoding encoding, 440 // Boolean isExternalRepresentation 441 // ); 442 // 443 // We make the following substitutions: 444 // 445 // CFStringRef -> i8* 446 // CFAllocatorRef -> i8* 447 // UInt8 * -> i8* 448 // CFIndex -> long (i32 or i64, as appropriate; we ask the module for its 449 // pointer size for now) CFStringEncoding -> i32 Boolean -> i8 450 451 Type *arg_type_array[5]; 452 453 arg_type_array[0] = i8_ptr_ty; 454 arg_type_array[1] = i8_ptr_ty; 455 arg_type_array[2] = m_intptr_ty; 456 arg_type_array[3] = i32_ty; 457 arg_type_array[4] = i8_ty; 458 459 ArrayRef<Type *> CFSCWB_arg_types(arg_type_array, 5); 460 461 llvm::FunctionType *CFSCWB_ty = 462 FunctionType::get(ns_str_ty, CFSCWB_arg_types, false); 463 464 // Build the constant containing the pointer to the function 465 PointerType *CFSCWB_ptr_ty = PointerType::getUnqual(CFSCWB_ty); 466 Constant *CFSCWB_addr_int = 467 ConstantInt::get(m_intptr_ty, CFStringCreateWithBytes_addr, false); 468 m_CFStringCreateWithBytes = { 469 CFSCWB_ty, ConstantExpr::getIntToPtr(CFSCWB_addr_int, CFSCWB_ptr_ty)}; 470 } 471 472 ConstantDataSequential *string_array = nullptr; 473 474 if (cstr) 475 string_array = dyn_cast<ConstantDataSequential>(cstr->getInitializer()); 476 477 Constant *alloc_arg = Constant::getNullValue(i8_ptr_ty); 478 Constant *bytes_arg = cstr ? ConstantExpr::getBitCast(cstr, i8_ptr_ty) 479 : Constant::getNullValue(i8_ptr_ty); 480 Constant *numBytes_arg = ConstantInt::get( 481 m_intptr_ty, cstr ? (string_array->getNumElements() - 1) * string_array->getElementByteSize() : 0, false); 482 int encoding_flags = 0; 483 switch (cstr ? string_array->getElementByteSize() : 1) { 484 case 1: 485 encoding_flags = 0x08000100; /* 0x08000100 is kCFStringEncodingUTF8 */ 486 break; 487 case 2: 488 encoding_flags = 0x0100; /* 0x0100 is kCFStringEncodingUTF16 */ 489 break; 490 case 4: 491 encoding_flags = 0x0c000100; /* 0x0c000100 is kCFStringEncodingUTF32 */ 492 break; 493 default: 494 encoding_flags = 0x0600; /* fall back to 0x0600, kCFStringEncodingASCII */ 495 LLDB_LOG(log, "Encountered an Objective-C constant string with unusual " 496 "element size {0}", 497 string_array->getElementByteSize()); 498 } 499 Constant *encoding_arg = ConstantInt::get(i32_ty, encoding_flags, false); 500 Constant *isExternal_arg = 501 ConstantInt::get(i8_ty, 0x0, false); /* 0x0 is false */ 502 503 Value *argument_array[5]; 504 505 argument_array[0] = alloc_arg; 506 argument_array[1] = bytes_arg; 507 argument_array[2] = numBytes_arg; 508 argument_array[3] = encoding_arg; 509 argument_array[4] = isExternal_arg; 510 511 ArrayRef<Value *> CFSCWB_arguments(argument_array, 5); 512 513 FunctionValueCache CFSCWB_Caller( 514 [this, &CFSCWB_arguments](llvm::Function *function) -> llvm::Value * { 515 return CallInst::Create( 516 m_CFStringCreateWithBytes, CFSCWB_arguments, 517 "CFStringCreateWithBytes", 518 llvm::cast<Instruction>( 519 m_entry_instruction_finder.GetValue(function))); 520 }); 521 522 if (!UnfoldConstant(ns_str, nullptr, CFSCWB_Caller, m_entry_instruction_finder, 523 m_error_stream)) { 524 LLDB_LOG(log, "Couldn't replace the NSString with the result of the call"); 525 526 m_error_stream.Printf("error [IRForTarget internal]: Couldn't replace an " 527 "Objective-C constant string with a dynamic " 528 "string\n"); 529 530 return false; 531 } 532 533 ns_str->eraseFromParent(); 534 535 return true; 536 } 537 538 bool IRForTarget::RewriteObjCConstStrings() { 539 lldb_private::Log *log(GetLog(LLDBLog::Expressions)); 540 541 ValueSymbolTable &value_symbol_table = m_module->getValueSymbolTable(); 542 543 for (StringMapEntry<llvm::Value *> &value_symbol : value_symbol_table) { 544 llvm::StringRef value_name = value_symbol.first(); 545 546 if (value_name.contains("_unnamed_cfstring_")) { 547 Value *nsstring_value = value_symbol.second; 548 549 GlobalVariable *nsstring_global = 550 dyn_cast<GlobalVariable>(nsstring_value); 551 552 if (!nsstring_global) { 553 LLDB_LOG(log, "NSString variable is not a GlobalVariable"); 554 555 m_error_stream.Printf("Internal error [IRForTarget]: An Objective-C " 556 "constant string is not a global variable\n"); 557 558 return false; 559 } 560 561 if (!nsstring_global->hasInitializer()) { 562 LLDB_LOG(log, "NSString variable does not have an initializer"); 563 564 m_error_stream.Printf("Internal error [IRForTarget]: An Objective-C " 565 "constant string does not have an initializer\n"); 566 567 return false; 568 } 569 570 ConstantStruct *nsstring_struct = 571 dyn_cast<ConstantStruct>(nsstring_global->getInitializer()); 572 573 if (!nsstring_struct) { 574 LLDB_LOG(log, 575 "NSString variable's initializer is not a ConstantStruct"); 576 577 m_error_stream.Printf("Internal error [IRForTarget]: An Objective-C " 578 "constant string is not a structure constant\n"); 579 580 return false; 581 } 582 583 // We expect the following structure: 584 // 585 // struct { 586 // int *isa; 587 // int flags; 588 // char *str; 589 // long length; 590 // }; 591 592 if (nsstring_struct->getNumOperands() != 4) { 593 594 LLDB_LOG(log, 595 "NSString variable's initializer structure has an " 596 "unexpected number of members. Should be 4, is {0}", 597 nsstring_struct->getNumOperands()); 598 599 m_error_stream.Printf("Internal error [IRForTarget]: The struct for an " 600 "Objective-C constant string is not as " 601 "expected\n"); 602 603 return false; 604 } 605 606 Constant *nsstring_member = nsstring_struct->getOperand(2); 607 608 if (!nsstring_member) { 609 LLDB_LOG(log, "NSString initializer's str element was empty"); 610 611 m_error_stream.Printf("Internal error [IRForTarget]: An Objective-C " 612 "constant string does not have a string " 613 "initializer\n"); 614 615 return false; 616 } 617 618 auto *cstr_global = dyn_cast<GlobalVariable>(nsstring_member); 619 if (!cstr_global) { 620 LLDB_LOG(log, 621 "NSString initializer's str element is not a GlobalVariable"); 622 623 m_error_stream.Printf("Internal error [IRForTarget]: Unhandled" 624 "constant string initializer\n"); 625 626 return false; 627 } 628 629 if (!cstr_global->hasInitializer()) { 630 LLDB_LOG(log, "NSString initializer's str element does not have an " 631 "initializer"); 632 633 m_error_stream.Printf("Internal error [IRForTarget]: An Objective-C " 634 "constant string's string initializer doesn't " 635 "point to initialized data\n"); 636 637 return false; 638 } 639 640 /* 641 if (!cstr_array) 642 { 643 if (log) 644 log->PutCString("NSString initializer's str element is not a 645 ConstantArray"); 646 647 if (m_error_stream) 648 m_error_stream.Printf("Internal error [IRForTarget]: An 649 Objective-C constant string's string initializer doesn't point to an 650 array\n"); 651 652 return false; 653 } 654 655 if (!cstr_array->isCString()) 656 { 657 if (log) 658 log->PutCString("NSString initializer's str element is not a C 659 string array"); 660 661 if (m_error_stream) 662 m_error_stream.Printf("Internal error [IRForTarget]: An 663 Objective-C constant string's string initializer doesn't point to a C 664 string\n"); 665 666 return false; 667 } 668 */ 669 670 ConstantDataArray *cstr_array = 671 dyn_cast<ConstantDataArray>(cstr_global->getInitializer()); 672 673 if (cstr_array) 674 LLDB_LOG(log, "Found NSString constant {0}, which contains \"{1}\"", 675 value_name, cstr_array->getAsString()); 676 else 677 LLDB_LOG(log, "Found NSString constant {0}, which contains \"\"", 678 value_name); 679 680 if (!cstr_array) 681 cstr_global = nullptr; 682 683 if (!RewriteObjCConstString(nsstring_global, cstr_global)) { 684 LLDB_LOG(log, "Error rewriting the constant string"); 685 686 // We don't print an error message here because RewriteObjCConstString 687 // has done so for us. 688 689 return false; 690 } 691 } 692 } 693 694 for (StringMapEntry<llvm::Value *> &value_symbol : value_symbol_table) { 695 llvm::StringRef value_name = value_symbol.first(); 696 697 if (value_name == "__CFConstantStringClassReference") { 698 GlobalVariable *gv = dyn_cast<GlobalVariable>(value_symbol.second); 699 700 if (!gv) { 701 LLDB_LOG(log, 702 "__CFConstantStringClassReference is not a global variable"); 703 704 m_error_stream.Printf("Internal error [IRForTarget]: Found a " 705 "CFConstantStringClassReference, but it is not a " 706 "global object\n"); 707 708 return false; 709 } 710 711 gv->eraseFromParent(); 712 713 break; 714 } 715 } 716 717 return true; 718 } 719 720 static bool IsObjCSelectorRef(Value *value) { 721 GlobalVariable *global_variable = dyn_cast<GlobalVariable>(value); 722 723 return !(!global_variable || !global_variable->hasName() || 724 !global_variable->getName().startswith("OBJC_SELECTOR_REFERENCES_")); 725 } 726 727 // This function does not report errors; its callers are responsible. 728 bool IRForTarget::RewriteObjCSelector(Instruction *selector_load) { 729 lldb_private::Log *log(GetLog(LLDBLog::Expressions)); 730 731 LoadInst *load = dyn_cast<LoadInst>(selector_load); 732 733 if (!load) 734 return false; 735 736 // Unpack the message name from the selector. In LLVM IR, an objc_msgSend 737 // gets represented as 738 // 739 // %sel = load ptr, ptr @OBJC_SELECTOR_REFERENCES_, align 8 740 // call i8 @objc_msgSend(ptr %obj, ptr %sel, ...) 741 // 742 // where %obj is the object pointer and %sel is the selector. 743 // 744 // @"OBJC_SELECTOR_REFERENCES_" is a pointer to a character array called 745 // @"\01L_OBJC_llvm_moduleETH_VAR_NAllvm_moduleE_". 746 // @"\01L_OBJC_llvm_moduleETH_VAR_NAllvm_moduleE_" contains the string. 747 748 // Find the pointer's initializer and get the string from its target. 749 750 GlobalVariable *_objc_selector_references_ = 751 dyn_cast<GlobalVariable>(load->getPointerOperand()); 752 753 if (!_objc_selector_references_ || 754 !_objc_selector_references_->hasInitializer()) 755 return false; 756 757 Constant *osr_initializer = _objc_selector_references_->getInitializer(); 758 if (!osr_initializer) 759 return false; 760 761 // Find the string's initializer (a ConstantArray) and get the string from it 762 763 GlobalVariable *_objc_meth_var_name_ = 764 dyn_cast<GlobalVariable>(osr_initializer); 765 766 if (!_objc_meth_var_name_ || !_objc_meth_var_name_->hasInitializer()) 767 return false; 768 769 Constant *omvn_initializer = _objc_meth_var_name_->getInitializer(); 770 771 ConstantDataArray *omvn_initializer_array = 772 dyn_cast<ConstantDataArray>(omvn_initializer); 773 774 if (!omvn_initializer_array->isString()) 775 return false; 776 777 std::string omvn_initializer_string = 778 std::string(omvn_initializer_array->getAsString()); 779 780 LLDB_LOG(log, "Found Objective-C selector reference \"{0}\"", 781 omvn_initializer_string); 782 783 // Construct a call to sel_registerName 784 785 if (!m_sel_registerName) { 786 lldb::addr_t sel_registerName_addr; 787 788 bool missing_weak = false; 789 static lldb_private::ConstString g_sel_registerName_str("sel_registerName"); 790 sel_registerName_addr = m_execution_unit.FindSymbol(g_sel_registerName_str, 791 missing_weak); 792 if (sel_registerName_addr == LLDB_INVALID_ADDRESS || missing_weak) 793 return false; 794 795 LLDB_LOG(log, "Found sel_registerName at {0}", sel_registerName_addr); 796 797 // Build the function type: struct objc_selector 798 // *sel_registerName(uint8_t*) 799 800 // The below code would be "more correct," but in actuality what's required 801 // is uint8_t* 802 // Type *sel_type = StructType::get(m_module->getContext()); 803 // Type *sel_ptr_type = PointerType::getUnqual(sel_type); 804 Type *sel_ptr_type = Type::getInt8PtrTy(m_module->getContext()); 805 806 Type *type_array[1]; 807 808 type_array[0] = llvm::Type::getInt8PtrTy(m_module->getContext()); 809 810 ArrayRef<Type *> srN_arg_types(type_array, 1); 811 812 llvm::FunctionType *srN_type = 813 FunctionType::get(sel_ptr_type, srN_arg_types, false); 814 815 // Build the constant containing the pointer to the function 816 PointerType *srN_ptr_ty = PointerType::getUnqual(srN_type); 817 Constant *srN_addr_int = 818 ConstantInt::get(m_intptr_ty, sel_registerName_addr, false); 819 m_sel_registerName = {srN_type, 820 ConstantExpr::getIntToPtr(srN_addr_int, srN_ptr_ty)}; 821 } 822 823 Value *argument_array[1]; 824 825 Constant *omvn_pointer = ConstantExpr::getBitCast( 826 _objc_meth_var_name_, Type::getInt8PtrTy(m_module->getContext())); 827 828 argument_array[0] = omvn_pointer; 829 830 ArrayRef<Value *> srN_arguments(argument_array, 1); 831 832 CallInst *srN_call = CallInst::Create(m_sel_registerName, srN_arguments, 833 "sel_registerName", selector_load); 834 835 // Replace the load with the call in all users 836 837 selector_load->replaceAllUsesWith(srN_call); 838 839 selector_load->eraseFromParent(); 840 841 return true; 842 } 843 844 bool IRForTarget::RewriteObjCSelectors(BasicBlock &basic_block) { 845 lldb_private::Log *log(GetLog(LLDBLog::Expressions)); 846 847 InstrList selector_loads; 848 849 for (Instruction &inst : basic_block) { 850 if (LoadInst *load = dyn_cast<LoadInst>(&inst)) 851 if (IsObjCSelectorRef(load->getPointerOperand())) 852 selector_loads.push_back(&inst); 853 } 854 855 for (Instruction *inst : selector_loads) { 856 if (!RewriteObjCSelector(inst)) { 857 m_error_stream.Printf("Internal error [IRForTarget]: Couldn't change a " 858 "static reference to an Objective-C selector to a " 859 "dynamic reference\n"); 860 861 LLDB_LOG(log, "Couldn't rewrite a reference to an Objective-C selector"); 862 863 return false; 864 } 865 } 866 867 return true; 868 } 869 870 static bool IsObjCClassReference(Value *value) { 871 GlobalVariable *global_variable = dyn_cast<GlobalVariable>(value); 872 873 return !(!global_variable || !global_variable->hasName() || 874 !global_variable->getName().startswith("OBJC_CLASS_REFERENCES_")); 875 } 876 877 // This function does not report errors; its callers are responsible. 878 bool IRForTarget::RewriteObjCClassReference(Instruction *class_load) { 879 lldb_private::Log *log(GetLog(LLDBLog::Expressions)); 880 881 LoadInst *load = dyn_cast<LoadInst>(class_load); 882 883 if (!load) 884 return false; 885 886 // Unpack the class name from the reference. In LLVM IR, a reference to an 887 // Objective-C class gets represented as 888 // 889 // %tmp = load %struct._objc_class*, 890 // %struct._objc_class** @OBJC_CLASS_REFERENCES_, align 4 891 // 892 // @"OBJC_CLASS_REFERENCES_ is a bitcast of a character array called 893 // @OBJC_CLASS_NAME_. @OBJC_CLASS_NAME contains the string. 894 895 // Find the pointer's initializer (a ConstantExpr with opcode BitCast) and 896 // get the string from its target 897 898 GlobalVariable *_objc_class_references_ = 899 dyn_cast<GlobalVariable>(load->getPointerOperand()); 900 901 if (!_objc_class_references_ || 902 !_objc_class_references_->hasInitializer()) 903 return false; 904 905 Constant *ocr_initializer = _objc_class_references_->getInitializer(); 906 907 ConstantExpr *ocr_initializer_expr = dyn_cast<ConstantExpr>(ocr_initializer); 908 909 if (!ocr_initializer_expr || 910 ocr_initializer_expr->getOpcode() != Instruction::BitCast) 911 return false; 912 913 Value *ocr_initializer_base = ocr_initializer_expr->getOperand(0); 914 915 if (!ocr_initializer_base) 916 return false; 917 918 // Find the string's initializer (a ConstantArray) and get the string from it 919 920 GlobalVariable *_objc_class_name_ = 921 dyn_cast<GlobalVariable>(ocr_initializer_base); 922 923 if (!_objc_class_name_ || !_objc_class_name_->hasInitializer()) 924 return false; 925 926 Constant *ocn_initializer = _objc_class_name_->getInitializer(); 927 928 ConstantDataArray *ocn_initializer_array = 929 dyn_cast<ConstantDataArray>(ocn_initializer); 930 931 if (!ocn_initializer_array->isString()) 932 return false; 933 934 std::string ocn_initializer_string = 935 std::string(ocn_initializer_array->getAsString()); 936 937 LLDB_LOG(log, "Found Objective-C class reference \"{0}\"", 938 ocn_initializer_string); 939 940 // Construct a call to objc_getClass 941 942 if (!m_objc_getClass) { 943 lldb::addr_t objc_getClass_addr; 944 945 bool missing_weak = false; 946 static lldb_private::ConstString g_objc_getClass_str("objc_getClass"); 947 objc_getClass_addr = m_execution_unit.FindSymbol(g_objc_getClass_str, 948 missing_weak); 949 if (objc_getClass_addr == LLDB_INVALID_ADDRESS || missing_weak) 950 return false; 951 952 LLDB_LOG(log, "Found objc_getClass at {0}", objc_getClass_addr); 953 954 // Build the function type: %struct._objc_class *objc_getClass(i8*) 955 956 Type *class_type = load->getType(); 957 Type *type_array[1]; 958 type_array[0] = llvm::Type::getInt8PtrTy(m_module->getContext()); 959 960 ArrayRef<Type *> ogC_arg_types(type_array, 1); 961 962 llvm::FunctionType *ogC_type = 963 FunctionType::get(class_type, ogC_arg_types, false); 964 965 // Build the constant containing the pointer to the function 966 PointerType *ogC_ptr_ty = PointerType::getUnqual(ogC_type); 967 Constant *ogC_addr_int = 968 ConstantInt::get(m_intptr_ty, objc_getClass_addr, false); 969 m_objc_getClass = {ogC_type, 970 ConstantExpr::getIntToPtr(ogC_addr_int, ogC_ptr_ty)}; 971 } 972 973 Value *argument_array[1]; 974 975 Constant *ocn_pointer = ConstantExpr::getBitCast( 976 _objc_class_name_, Type::getInt8PtrTy(m_module->getContext())); 977 978 argument_array[0] = ocn_pointer; 979 980 ArrayRef<Value *> ogC_arguments(argument_array, 1); 981 982 CallInst *ogC_call = CallInst::Create(m_objc_getClass, ogC_arguments, 983 "objc_getClass", class_load); 984 985 // Replace the load with the call in all users 986 987 class_load->replaceAllUsesWith(ogC_call); 988 989 class_load->eraseFromParent(); 990 991 return true; 992 } 993 994 bool IRForTarget::RewriteObjCClassReferences(BasicBlock &basic_block) { 995 lldb_private::Log *log(GetLog(LLDBLog::Expressions)); 996 997 InstrList class_loads; 998 999 for (Instruction &inst : basic_block) { 1000 if (LoadInst *load = dyn_cast<LoadInst>(&inst)) 1001 if (IsObjCClassReference(load->getPointerOperand())) 1002 class_loads.push_back(&inst); 1003 } 1004 1005 for (Instruction *inst : class_loads) { 1006 if (!RewriteObjCClassReference(inst)) { 1007 m_error_stream.Printf("Internal error [IRForTarget]: Couldn't change a " 1008 "static reference to an Objective-C class to a " 1009 "dynamic reference\n"); 1010 1011 LLDB_LOG(log, "Couldn't rewrite a reference to an Objective-C class"); 1012 1013 return false; 1014 } 1015 } 1016 1017 return true; 1018 } 1019 1020 // This function does not report errors; its callers are responsible. 1021 bool IRForTarget::RewritePersistentAlloc(llvm::Instruction *persistent_alloc) { 1022 lldb_private::Log *log(GetLog(LLDBLog::Expressions)); 1023 1024 AllocaInst *alloc = dyn_cast<AllocaInst>(persistent_alloc); 1025 1026 MDNode *alloc_md = alloc->getMetadata("clang.decl.ptr"); 1027 1028 if (!alloc_md || !alloc_md->getNumOperands()) 1029 return false; 1030 1031 ConstantInt *constant_int = 1032 mdconst::dyn_extract<ConstantInt>(alloc_md->getOperand(0)); 1033 1034 if (!constant_int) 1035 return false; 1036 1037 // We attempt to register this as a new persistent variable with the DeclMap. 1038 1039 uintptr_t ptr = constant_int->getZExtValue(); 1040 1041 clang::VarDecl *decl = reinterpret_cast<clang::VarDecl *>(ptr); 1042 1043 lldb_private::TypeFromParser result_decl_type( 1044 m_decl_map->GetTypeSystem()->GetType(decl->getType())); 1045 1046 StringRef decl_name(decl->getName()); 1047 lldb_private::ConstString persistent_variable_name(decl_name.data(), 1048 decl_name.size()); 1049 if (!m_decl_map->AddPersistentVariable(decl, persistent_variable_name, 1050 result_decl_type, false, false)) 1051 return false; 1052 1053 GlobalVariable *persistent_global = new GlobalVariable( 1054 (*m_module), alloc->getType(), false, /* not constant */ 1055 GlobalValue::ExternalLinkage, nullptr, /* no initializer */ 1056 alloc->getName().str()); 1057 1058 // What we're going to do here is make believe this was a regular old 1059 // external variable. That means we need to make the metadata valid. 1060 1061 NamedMDNode *named_metadata = 1062 m_module->getOrInsertNamedMetadata("clang.global.decl.ptrs"); 1063 1064 llvm::Metadata *values[2]; 1065 values[0] = ConstantAsMetadata::get(persistent_global); 1066 values[1] = ConstantAsMetadata::get(constant_int); 1067 1068 ArrayRef<llvm::Metadata *> value_ref(values, 2); 1069 1070 MDNode *persistent_global_md = MDNode::get(m_module->getContext(), value_ref); 1071 named_metadata->addOperand(persistent_global_md); 1072 1073 // Now, since the variable is a pointer variable, we will drop in a load of 1074 // that pointer variable. 1075 1076 LoadInst *persistent_load = new LoadInst(persistent_global->getValueType(), 1077 persistent_global, "", alloc); 1078 1079 LLDB_LOG(log, "Replacing \"{0}\" with \"{1}\"", PrintValue(alloc), 1080 PrintValue(persistent_load)); 1081 1082 alloc->replaceAllUsesWith(persistent_load); 1083 alloc->eraseFromParent(); 1084 1085 return true; 1086 } 1087 1088 bool IRForTarget::RewritePersistentAllocs(llvm::BasicBlock &basic_block) { 1089 if (!m_resolve_vars) 1090 return true; 1091 1092 lldb_private::Log *log(GetLog(LLDBLog::Expressions)); 1093 1094 InstrList pvar_allocs; 1095 1096 for (Instruction &inst : basic_block) { 1097 1098 if (AllocaInst *alloc = dyn_cast<AllocaInst>(&inst)) { 1099 llvm::StringRef alloc_name = alloc->getName(); 1100 1101 if (alloc_name.startswith("$") && !alloc_name.startswith("$__lldb")) { 1102 if (alloc_name.find_first_of("0123456789") == 1) { 1103 LLDB_LOG(log, "Rejecting a numeric persistent variable."); 1104 1105 m_error_stream.Printf("Error [IRForTarget]: Names starting with $0, " 1106 "$1, ... are reserved for use as result " 1107 "names\n"); 1108 1109 return false; 1110 } 1111 1112 pvar_allocs.push_back(alloc); 1113 } 1114 } 1115 } 1116 1117 for (Instruction *inst : pvar_allocs) { 1118 if (!RewritePersistentAlloc(inst)) { 1119 m_error_stream.Printf("Internal error [IRForTarget]: Couldn't rewrite " 1120 "the creation of a persistent variable\n"); 1121 1122 LLDB_LOG(log, "Couldn't rewrite the creation of a persistent variable"); 1123 1124 return false; 1125 } 1126 } 1127 1128 return true; 1129 } 1130 1131 // This function does not report errors; its callers are responsible. 1132 bool IRForTarget::MaybeHandleVariable(Value *llvm_value_ptr) { 1133 lldb_private::Log *log(GetLog(LLDBLog::Expressions)); 1134 1135 LLDB_LOG(log, "MaybeHandleVariable ({0})", PrintValue(llvm_value_ptr)); 1136 1137 if (ConstantExpr *constant_expr = dyn_cast<ConstantExpr>(llvm_value_ptr)) { 1138 switch (constant_expr->getOpcode()) { 1139 default: 1140 break; 1141 case Instruction::GetElementPtr: 1142 case Instruction::BitCast: 1143 Value *s = constant_expr->getOperand(0); 1144 if (!MaybeHandleVariable(s)) 1145 return false; 1146 } 1147 } else if (GlobalVariable *global_variable = 1148 dyn_cast<GlobalVariable>(llvm_value_ptr)) { 1149 if (!GlobalValue::isExternalLinkage(global_variable->getLinkage())) 1150 return true; 1151 1152 clang::NamedDecl *named_decl = DeclForGlobal(global_variable); 1153 1154 if (!named_decl) { 1155 if (IsObjCSelectorRef(llvm_value_ptr)) 1156 return true; 1157 1158 if (!global_variable->hasExternalLinkage()) 1159 return true; 1160 1161 LLDB_LOG(log, "Found global variable \"{0}\" without metadata", 1162 global_variable->getName()); 1163 1164 return false; 1165 } 1166 1167 llvm::StringRef name(named_decl->getName()); 1168 1169 clang::ValueDecl *value_decl = dyn_cast<clang::ValueDecl>(named_decl); 1170 if (value_decl == nullptr) 1171 return false; 1172 1173 lldb_private::CompilerType compiler_type = 1174 m_decl_map->GetTypeSystem()->GetType(value_decl->getType()); 1175 1176 const Type *value_type = nullptr; 1177 1178 if (name.startswith("$")) { 1179 // The $__lldb_expr_result name indicates the return value has allocated 1180 // as a static variable. Per the comment at 1181 // ASTResultSynthesizer::SynthesizeBodyResult, accesses to this static 1182 // variable need to be redirected to the result of dereferencing a 1183 // pointer that is passed in as one of the arguments. 1184 // 1185 // Consequently, when reporting the size of the type, we report a pointer 1186 // type pointing to the type of $__lldb_expr_result, not the type itself. 1187 // 1188 // We also do this for any user-declared persistent variables. 1189 compiler_type = compiler_type.GetPointerType(); 1190 value_type = PointerType::get(global_variable->getType(), 0); 1191 } else { 1192 value_type = global_variable->getType(); 1193 } 1194 1195 auto *target = m_execution_unit.GetTarget().get(); 1196 llvm::Optional<uint64_t> value_size = compiler_type.GetByteSize(target); 1197 if (!value_size) 1198 return false; 1199 llvm::Optional<size_t> opt_alignment = 1200 compiler_type.GetTypeBitAlign(target); 1201 if (!opt_alignment) 1202 return false; 1203 lldb::offset_t value_alignment = (*opt_alignment + 7ull) / 8ull; 1204 1205 LLDB_LOG(log, 1206 "Type of \"{0}\" is [clang \"{1}\", llvm \"{2}\"] [size {3}, " 1207 "align {4}]", 1208 name, 1209 lldb_private::ClangUtil::GetQualType(compiler_type).getAsString(), 1210 PrintType(value_type), *value_size, value_alignment); 1211 1212 if (named_decl) 1213 m_decl_map->AddValueToStruct(named_decl, lldb_private::ConstString(name), 1214 llvm_value_ptr, *value_size, 1215 value_alignment); 1216 } else if (isa<llvm::Function>(llvm_value_ptr)) { 1217 LLDB_LOG(log, "Function pointers aren't handled right now"); 1218 1219 return false; 1220 } 1221 1222 return true; 1223 } 1224 1225 // This function does not report errors; its callers are responsible. 1226 bool IRForTarget::HandleSymbol(Value *symbol) { 1227 lldb_private::Log *log(GetLog(LLDBLog::Expressions)); 1228 1229 lldb_private::ConstString name(symbol->getName().str().c_str()); 1230 1231 lldb::addr_t symbol_addr = 1232 m_decl_map->GetSymbolAddress(name, lldb::eSymbolTypeAny); 1233 1234 if (symbol_addr == LLDB_INVALID_ADDRESS) { 1235 LLDB_LOG(log, "Symbol \"{0}\" had no address", name); 1236 1237 return false; 1238 } 1239 1240 LLDB_LOG(log, "Found \"{0}\" at {1}", name, symbol_addr); 1241 1242 Type *symbol_type = symbol->getType(); 1243 1244 Constant *symbol_addr_int = ConstantInt::get(m_intptr_ty, symbol_addr, false); 1245 1246 Value *symbol_addr_ptr = 1247 ConstantExpr::getIntToPtr(symbol_addr_int, symbol_type); 1248 1249 LLDB_LOG(log, "Replacing {0} with {1}", PrintValue(symbol), 1250 PrintValue(symbol_addr_ptr)); 1251 1252 symbol->replaceAllUsesWith(symbol_addr_ptr); 1253 1254 return true; 1255 } 1256 1257 bool IRForTarget::MaybeHandleCallArguments(CallInst *Old) { 1258 lldb_private::Log *log(GetLog(LLDBLog::Expressions)); 1259 1260 LLDB_LOG(log, "MaybeHandleCallArguments({0})", PrintValue(Old)); 1261 1262 for (unsigned op_index = 0, num_ops = Old->arg_size(); 1263 op_index < num_ops; ++op_index) 1264 // conservatively believe that this is a store 1265 if (!MaybeHandleVariable(Old->getArgOperand(op_index))) { 1266 m_error_stream.Printf("Internal error [IRForTarget]: Couldn't rewrite " 1267 "one of the arguments of a function call.\n"); 1268 1269 return false; 1270 } 1271 1272 return true; 1273 } 1274 1275 bool IRForTarget::HandleObjCClass(Value *classlist_reference) { 1276 lldb_private::Log *log(GetLog(LLDBLog::Expressions)); 1277 1278 GlobalVariable *global_variable = 1279 dyn_cast<GlobalVariable>(classlist_reference); 1280 1281 if (!global_variable) 1282 return false; 1283 1284 Constant *initializer = global_variable->getInitializer(); 1285 1286 if (!initializer) 1287 return false; 1288 1289 if (!initializer->hasName()) 1290 return false; 1291 1292 StringRef name(initializer->getName()); 1293 lldb_private::ConstString name_cstr(name.str().c_str()); 1294 lldb::addr_t class_ptr = 1295 m_decl_map->GetSymbolAddress(name_cstr, lldb::eSymbolTypeObjCClass); 1296 1297 LLDB_LOG(log, "Found reference to Objective-C class {0} ({1})", name, 1298 (unsigned long long)class_ptr); 1299 1300 if (class_ptr == LLDB_INVALID_ADDRESS) 1301 return false; 1302 1303 if (global_variable->use_empty()) 1304 return false; 1305 1306 SmallVector<LoadInst *, 2> load_instructions; 1307 1308 for (llvm::User *u : global_variable->users()) { 1309 if (LoadInst *load_instruction = dyn_cast<LoadInst>(u)) 1310 load_instructions.push_back(load_instruction); 1311 } 1312 1313 if (load_instructions.empty()) 1314 return false; 1315 1316 Constant *class_addr = ConstantInt::get(m_intptr_ty, (uint64_t)class_ptr); 1317 1318 for (LoadInst *load_instruction : load_instructions) { 1319 Constant *class_bitcast = 1320 ConstantExpr::getIntToPtr(class_addr, load_instruction->getType()); 1321 1322 load_instruction->replaceAllUsesWith(class_bitcast); 1323 1324 load_instruction->eraseFromParent(); 1325 } 1326 1327 return true; 1328 } 1329 1330 bool IRForTarget::RemoveCXAAtExit(BasicBlock &basic_block) { 1331 std::vector<CallInst *> calls_to_remove; 1332 1333 for (Instruction &inst : basic_block) { 1334 CallInst *call = dyn_cast<CallInst>(&inst); 1335 1336 // MaybeHandleCallArguments handles error reporting; we are silent here 1337 if (!call) 1338 continue; 1339 1340 bool remove = false; 1341 1342 llvm::Function *func = call->getCalledFunction(); 1343 1344 if (func && func->getName() == "__cxa_atexit") 1345 remove = true; 1346 1347 llvm::Value *val = call->getCalledOperand(); 1348 1349 if (val && val->getName() == "__cxa_atexit") 1350 remove = true; 1351 1352 if (remove) 1353 calls_to_remove.push_back(call); 1354 } 1355 1356 for (CallInst *ci : calls_to_remove) 1357 ci->eraseFromParent(); 1358 1359 return true; 1360 } 1361 1362 bool IRForTarget::ResolveCalls(BasicBlock &basic_block) { 1363 // Prepare the current basic block for execution in the remote process 1364 1365 for (Instruction &inst : basic_block) { 1366 CallInst *call = dyn_cast<CallInst>(&inst); 1367 1368 // MaybeHandleCallArguments handles error reporting; we are silent here 1369 if (call && !MaybeHandleCallArguments(call)) 1370 return false; 1371 } 1372 1373 return true; 1374 } 1375 1376 bool IRForTarget::ResolveExternals(Function &llvm_function) { 1377 lldb_private::Log *log(GetLog(LLDBLog::Expressions)); 1378 1379 for (GlobalVariable &global_var : m_module->globals()) { 1380 llvm::StringRef global_name = global_var.getName(); 1381 1382 LLDB_LOG(log, "Examining {0}, DeclForGlobalValue returns {1}", global_name, 1383 static_cast<void *>(DeclForGlobal(&global_var))); 1384 1385 if (global_name.startswith("OBJC_IVAR")) { 1386 if (!HandleSymbol(&global_var)) { 1387 m_error_stream.Format("Error [IRForTarget]: Couldn't find Objective-C " 1388 "indirect ivar symbol {0}\n", 1389 global_name); 1390 1391 return false; 1392 } 1393 } else if (global_name.contains("OBJC_CLASSLIST_REFERENCES_$")) { 1394 if (!HandleObjCClass(&global_var)) { 1395 m_error_stream.Printf("Error [IRForTarget]: Couldn't resolve the class " 1396 "for an Objective-C static method call\n"); 1397 1398 return false; 1399 } 1400 } else if (global_name.contains("OBJC_CLASSLIST_SUP_REFS_$")) { 1401 if (!HandleObjCClass(&global_var)) { 1402 m_error_stream.Printf("Error [IRForTarget]: Couldn't resolve the class " 1403 "for an Objective-C static method call\n"); 1404 1405 return false; 1406 } 1407 } else if (DeclForGlobal(&global_var)) { 1408 if (!MaybeHandleVariable(&global_var)) { 1409 m_error_stream.Format("Internal error [IRForTarget]: Couldn't rewrite " 1410 "external variable {0}\n", 1411 global_name); 1412 1413 return false; 1414 } 1415 } 1416 } 1417 1418 return true; 1419 } 1420 1421 static bool isGuardVariableRef(Value *V) { 1422 Constant *Old = dyn_cast<Constant>(V); 1423 1424 if (!Old) 1425 return false; 1426 1427 if (auto CE = dyn_cast<ConstantExpr>(V)) { 1428 if (CE->getOpcode() != Instruction::BitCast) 1429 return false; 1430 1431 Old = CE->getOperand(0); 1432 } 1433 1434 GlobalVariable *GV = dyn_cast<GlobalVariable>(Old); 1435 1436 if (!GV || !GV->hasName() || !isGuardVariableSymbol(GV->getName())) 1437 return false; 1438 1439 return true; 1440 } 1441 1442 void IRForTarget::TurnGuardLoadIntoZero(llvm::Instruction *guard_load) { 1443 Constant *zero(Constant::getNullValue(guard_load->getType())); 1444 guard_load->replaceAllUsesWith(zero); 1445 guard_load->eraseFromParent(); 1446 } 1447 1448 static void ExciseGuardStore(Instruction *guard_store) { 1449 guard_store->eraseFromParent(); 1450 } 1451 1452 bool IRForTarget::RemoveGuards(BasicBlock &basic_block) { 1453 // Eliminate any reference to guard variables found. 1454 1455 InstrList guard_loads; 1456 InstrList guard_stores; 1457 1458 for (Instruction &inst : basic_block) { 1459 1460 if (LoadInst *load = dyn_cast<LoadInst>(&inst)) 1461 if (isGuardVariableRef(load->getPointerOperand())) 1462 guard_loads.push_back(&inst); 1463 1464 if (StoreInst *store = dyn_cast<StoreInst>(&inst)) 1465 if (isGuardVariableRef(store->getPointerOperand())) 1466 guard_stores.push_back(&inst); 1467 } 1468 1469 for (Instruction *inst : guard_loads) 1470 TurnGuardLoadIntoZero(inst); 1471 1472 for (Instruction *inst : guard_stores) 1473 ExciseGuardStore(inst); 1474 1475 return true; 1476 } 1477 1478 // This function does not report errors; its callers are responsible. 1479 bool IRForTarget::UnfoldConstant(Constant *old_constant, 1480 llvm::Function *llvm_function, 1481 FunctionValueCache &value_maker, 1482 FunctionValueCache &entry_instruction_finder, 1483 lldb_private::Stream &error_stream) { 1484 SmallVector<User *, 16> users; 1485 1486 // We do this because the use list might change, invalidating our iterator. 1487 // Much better to keep a work list ourselves. 1488 for (llvm::User *u : old_constant->users()) 1489 users.push_back(u); 1490 1491 for (size_t i = 0; i < users.size(); ++i) { 1492 User *user = users[i]; 1493 1494 if (Constant *constant = dyn_cast<Constant>(user)) { 1495 // synthesize a new non-constant equivalent of the constant 1496 1497 if (ConstantExpr *constant_expr = dyn_cast<ConstantExpr>(constant)) { 1498 switch (constant_expr->getOpcode()) { 1499 default: 1500 error_stream.Printf("error [IRForTarget internal]: Unhandled " 1501 "constant expression type: \"%s\"", 1502 PrintValue(constant_expr).c_str()); 1503 return false; 1504 case Instruction::BitCast: { 1505 FunctionValueCache bit_cast_maker( 1506 [&value_maker, &entry_instruction_finder, old_constant, 1507 constant_expr](llvm::Function *function) -> llvm::Value * { 1508 // UnaryExpr 1509 // OperandList[0] is value 1510 1511 if (constant_expr->getOperand(0) != old_constant) 1512 return constant_expr; 1513 1514 return new BitCastInst( 1515 value_maker.GetValue(function), constant_expr->getType(), 1516 "", llvm::cast<Instruction>( 1517 entry_instruction_finder.GetValue(function))); 1518 }); 1519 1520 if (!UnfoldConstant(constant_expr, llvm_function, bit_cast_maker, 1521 entry_instruction_finder, error_stream)) 1522 return false; 1523 } break; 1524 case Instruction::GetElementPtr: { 1525 // GetElementPtrConstantExpr 1526 // OperandList[0] is base 1527 // OperandList[1]... are indices 1528 1529 FunctionValueCache get_element_pointer_maker( 1530 [&value_maker, &entry_instruction_finder, old_constant, 1531 constant_expr](llvm::Function *function) -> llvm::Value * { 1532 auto *gep = cast<llvm::GEPOperator>(constant_expr); 1533 Value *ptr = gep->getPointerOperand(); 1534 1535 if (ptr == old_constant) 1536 ptr = value_maker.GetValue(function); 1537 1538 std::vector<Value *> index_vector; 1539 for (Value *operand : gep->indices()) { 1540 if (operand == old_constant) 1541 operand = value_maker.GetValue(function); 1542 1543 index_vector.push_back(operand); 1544 } 1545 1546 ArrayRef<Value *> indices(index_vector); 1547 1548 return GetElementPtrInst::Create( 1549 gep->getSourceElementType(), ptr, indices, "", 1550 llvm::cast<Instruction>( 1551 entry_instruction_finder.GetValue(function))); 1552 }); 1553 1554 if (!UnfoldConstant(constant_expr, llvm_function, 1555 get_element_pointer_maker, 1556 entry_instruction_finder, error_stream)) 1557 return false; 1558 } break; 1559 } 1560 } else { 1561 error_stream.Printf( 1562 "error [IRForTarget internal]: Unhandled constant type: \"%s\"", 1563 PrintValue(constant).c_str()); 1564 return false; 1565 } 1566 } else { 1567 if (Instruction *inst = llvm::dyn_cast<Instruction>(user)) { 1568 if (llvm_function && inst->getParent()->getParent() != llvm_function) { 1569 error_stream.PutCString("error: Capturing non-local variables in " 1570 "expressions is unsupported.\n"); 1571 return false; 1572 } 1573 inst->replaceUsesOfWith( 1574 old_constant, value_maker.GetValue(inst->getParent()->getParent())); 1575 } else { 1576 error_stream.Printf( 1577 "error [IRForTarget internal]: Unhandled non-constant type: \"%s\"", 1578 PrintValue(user).c_str()); 1579 return false; 1580 } 1581 } 1582 } 1583 1584 if (!isa<GlobalValue>(old_constant)) { 1585 old_constant->destroyConstant(); 1586 } 1587 1588 return true; 1589 } 1590 1591 bool IRForTarget::ReplaceVariables(Function &llvm_function) { 1592 if (!m_resolve_vars) 1593 return true; 1594 1595 lldb_private::Log *log(GetLog(LLDBLog::Expressions)); 1596 1597 m_decl_map->DoStructLayout(); 1598 1599 LLDB_LOG(log, "Element arrangement:"); 1600 1601 uint32_t num_elements; 1602 uint32_t element_index; 1603 1604 size_t size; 1605 lldb::offset_t alignment; 1606 1607 if (!m_decl_map->GetStructInfo(num_elements, size, alignment)) 1608 return false; 1609 1610 Function::arg_iterator iter(llvm_function.arg_begin()); 1611 1612 if (iter == llvm_function.arg_end()) { 1613 m_error_stream.Printf("Internal error [IRForTarget]: Wrapper takes no " 1614 "arguments (should take at least a struct pointer)"); 1615 1616 return false; 1617 } 1618 1619 Argument *argument = &*iter; 1620 1621 if (argument->getName().equals("this")) { 1622 ++iter; 1623 1624 if (iter == llvm_function.arg_end()) { 1625 m_error_stream.Printf("Internal error [IRForTarget]: Wrapper takes only " 1626 "'this' argument (should take a struct pointer " 1627 "too)"); 1628 1629 return false; 1630 } 1631 1632 argument = &*iter; 1633 } else if (argument->getName().equals("self")) { 1634 ++iter; 1635 1636 if (iter == llvm_function.arg_end()) { 1637 m_error_stream.Printf("Internal error [IRForTarget]: Wrapper takes only " 1638 "'self' argument (should take '_cmd' and a struct " 1639 "pointer too)"); 1640 1641 return false; 1642 } 1643 1644 if (!iter->getName().equals("_cmd")) { 1645 m_error_stream.Format("Internal error [IRForTarget]: Wrapper takes '{0}' " 1646 "after 'self' argument (should take '_cmd')", 1647 iter->getName()); 1648 1649 return false; 1650 } 1651 1652 ++iter; 1653 1654 if (iter == llvm_function.arg_end()) { 1655 m_error_stream.Printf("Internal error [IRForTarget]: Wrapper takes only " 1656 "'self' and '_cmd' arguments (should take a struct " 1657 "pointer too)"); 1658 1659 return false; 1660 } 1661 1662 argument = &*iter; 1663 } 1664 1665 if (!argument->getName().equals("$__lldb_arg")) { 1666 m_error_stream.Format("Internal error [IRForTarget]: Wrapper takes an " 1667 "argument named '{0}' instead of the struct pointer", 1668 argument->getName()); 1669 1670 return false; 1671 } 1672 1673 LLDB_LOG(log, "Arg: \"{0}\"", PrintValue(argument)); 1674 1675 BasicBlock &entry_block(llvm_function.getEntryBlock()); 1676 Instruction *FirstEntryInstruction(entry_block.getFirstNonPHIOrDbg()); 1677 1678 if (!FirstEntryInstruction) { 1679 m_error_stream.Printf("Internal error [IRForTarget]: Couldn't find the " 1680 "first instruction in the wrapper for use in " 1681 "rewriting"); 1682 1683 return false; 1684 } 1685 1686 LLVMContext &context(m_module->getContext()); 1687 IntegerType *offset_type(Type::getInt32Ty(context)); 1688 1689 if (!offset_type) { 1690 m_error_stream.Printf( 1691 "Internal error [IRForTarget]: Couldn't produce an offset type"); 1692 1693 return false; 1694 } 1695 1696 for (element_index = 0; element_index < num_elements; ++element_index) { 1697 const clang::NamedDecl *decl = nullptr; 1698 Value *value = nullptr; 1699 lldb::offset_t offset; 1700 lldb_private::ConstString name; 1701 1702 if (!m_decl_map->GetStructElement(decl, value, offset, name, 1703 element_index)) { 1704 m_error_stream.Printf( 1705 "Internal error [IRForTarget]: Structure information is incomplete"); 1706 1707 return false; 1708 } 1709 1710 LLDB_LOG(log, " \"{0}\" (\"{1}\") placed at {2}", name, 1711 decl->getNameAsString(), offset); 1712 1713 if (value) { 1714 LLDB_LOG(log, " Replacing [{0}]", PrintValue(value)); 1715 1716 FunctionValueCache body_result_maker( 1717 [this, name, offset_type, offset, argument, 1718 value](llvm::Function *function) -> llvm::Value * { 1719 // Per the comment at ASTResultSynthesizer::SynthesizeBodyResult, 1720 // in cases where the result variable is an rvalue, we have to 1721 // synthesize a dereference of the appropriate structure entry in 1722 // order to produce the static variable that the AST thinks it is 1723 // accessing. 1724 1725 llvm::Instruction *entry_instruction = llvm::cast<Instruction>( 1726 m_entry_instruction_finder.GetValue(function)); 1727 1728 Type *int8Ty = Type::getInt8Ty(function->getContext()); 1729 ConstantInt *offset_int( 1730 ConstantInt::get(offset_type, offset, true)); 1731 GetElementPtrInst *get_element_ptr = GetElementPtrInst::Create( 1732 int8Ty, argument, offset_int, "", entry_instruction); 1733 1734 if (name == m_result_name && !m_result_is_pointer) { 1735 BitCastInst *bit_cast = new BitCastInst( 1736 get_element_ptr, value->getType()->getPointerTo(), "", 1737 entry_instruction); 1738 1739 LoadInst *load = new LoadInst(value->getType(), bit_cast, "", 1740 entry_instruction); 1741 1742 return load; 1743 } else { 1744 BitCastInst *bit_cast = new BitCastInst( 1745 get_element_ptr, value->getType(), "", entry_instruction); 1746 1747 return bit_cast; 1748 } 1749 }); 1750 1751 if (Constant *constant = dyn_cast<Constant>(value)) { 1752 if (!UnfoldConstant(constant, &llvm_function, body_result_maker, 1753 m_entry_instruction_finder, m_error_stream)) { 1754 return false; 1755 } 1756 } else if (Instruction *instruction = dyn_cast<Instruction>(value)) { 1757 if (instruction->getParent()->getParent() != &llvm_function) { 1758 m_error_stream.PutCString("error: Capturing non-local variables in " 1759 "expressions is unsupported.\n"); 1760 return false; 1761 } 1762 value->replaceAllUsesWith( 1763 body_result_maker.GetValue(instruction->getParent()->getParent())); 1764 } else { 1765 LLDB_LOG(log, "Unhandled non-constant type: \"{0}\"", 1766 PrintValue(value)); 1767 return false; 1768 } 1769 1770 if (GlobalVariable *var = dyn_cast<GlobalVariable>(value)) 1771 var->eraseFromParent(); 1772 } 1773 } 1774 1775 LLDB_LOG(log, "Total structure [align {0}, size {1}]", (int64_t)alignment, 1776 (uint64_t)size); 1777 1778 return true; 1779 } 1780 1781 bool IRForTarget::runOnModule(Module &llvm_module) { 1782 lldb_private::Log *log(GetLog(LLDBLog::Expressions)); 1783 1784 m_module = &llvm_module; 1785 m_target_data = std::make_unique<DataLayout>(m_module); 1786 m_intptr_ty = llvm::Type::getIntNTy(m_module->getContext(), 1787 m_target_data->getPointerSizeInBits()); 1788 1789 if (log) { 1790 std::string s; 1791 raw_string_ostream oss(s); 1792 1793 m_module->print(oss, nullptr); 1794 1795 oss.flush(); 1796 1797 LLDB_LOG(log, "Module as passed in to IRForTarget: \n\"{0}\"", s); 1798 } 1799 1800 Function *const main_function = 1801 m_func_name.IsEmpty() ? nullptr 1802 : m_module->getFunction(m_func_name.GetStringRef()); 1803 1804 if (!m_func_name.IsEmpty() && !main_function) { 1805 LLDB_LOG(log, "Couldn't find \"{0}()\" in the module", m_func_name); 1806 1807 m_error_stream.Format("Internal error [IRForTarget]: Couldn't find wrapper " 1808 "'{0}' in the module", 1809 m_func_name); 1810 1811 return false; 1812 } 1813 1814 if (main_function) { 1815 if (!FixFunctionLinkage(*main_function)) { 1816 LLDB_LOG(log, "Couldn't fix the linkage for the function"); 1817 1818 return false; 1819 } 1820 } 1821 1822 llvm::Type *int8_ty = Type::getInt8Ty(m_module->getContext()); 1823 1824 m_reloc_placeholder = new llvm::GlobalVariable( 1825 (*m_module), int8_ty, false /* IsConstant */, 1826 GlobalVariable::InternalLinkage, Constant::getNullValue(int8_ty), 1827 "reloc_placeholder", nullptr /* InsertBefore */, 1828 GlobalVariable::NotThreadLocal /* ThreadLocal */, 0 /* AddressSpace */); 1829 1830 //////////////////////////////////////////////////////////// 1831 // Replace $__lldb_expr_result with a persistent variable 1832 // 1833 1834 if (main_function) { 1835 if (!CreateResultVariable(*main_function)) { 1836 LLDB_LOG(log, "CreateResultVariable() failed"); 1837 1838 // CreateResultVariable() reports its own errors, so we don't do so here 1839 1840 return false; 1841 } 1842 } 1843 1844 if (log && log->GetVerbose()) { 1845 std::string s; 1846 raw_string_ostream oss(s); 1847 1848 m_module->print(oss, nullptr); 1849 1850 oss.flush(); 1851 1852 LLDB_LOG(log, "Module after creating the result variable: \n\"{0}\"", s); 1853 } 1854 1855 for (llvm::Function &function : *m_module) { 1856 for (BasicBlock &bb : function) { 1857 if (!RemoveGuards(bb)) { 1858 LLDB_LOG(log, "RemoveGuards() failed"); 1859 1860 // RemoveGuards() reports its own errors, so we don't do so here 1861 1862 return false; 1863 } 1864 1865 if (!RewritePersistentAllocs(bb)) { 1866 LLDB_LOG(log, "RewritePersistentAllocs() failed"); 1867 1868 // RewritePersistentAllocs() reports its own errors, so we don't do so 1869 // here 1870 1871 return false; 1872 } 1873 1874 if (!RemoveCXAAtExit(bb)) { 1875 LLDB_LOG(log, "RemoveCXAAtExit() failed"); 1876 1877 // RemoveCXAAtExit() reports its own errors, so we don't do so here 1878 1879 return false; 1880 } 1881 } 1882 } 1883 1884 /////////////////////////////////////////////////////////////////////////////// 1885 // Fix all Objective-C constant strings to use NSStringWithCString:encoding: 1886 // 1887 1888 if (!RewriteObjCConstStrings()) { 1889 LLDB_LOG(log, "RewriteObjCConstStrings() failed"); 1890 1891 // RewriteObjCConstStrings() reports its own errors, so we don't do so here 1892 1893 return false; 1894 } 1895 1896 for (llvm::Function &function : *m_module) { 1897 for (llvm::BasicBlock &bb : function) { 1898 if (!RewriteObjCSelectors(bb)) { 1899 LLDB_LOG(log, "RewriteObjCSelectors() failed"); 1900 1901 // RewriteObjCSelectors() reports its own errors, so we don't do so 1902 // here 1903 1904 return false; 1905 } 1906 1907 if (!RewriteObjCClassReferences(bb)) { 1908 LLDB_LOG(log, "RewriteObjCClassReferences() failed"); 1909 1910 // RewriteObjCClasses() reports its own errors, so we don't do so here 1911 1912 return false; 1913 } 1914 } 1915 } 1916 1917 for (llvm::Function &function : *m_module) { 1918 for (BasicBlock &bb : function) { 1919 if (!ResolveCalls(bb)) { 1920 LLDB_LOG(log, "ResolveCalls() failed"); 1921 1922 // ResolveCalls() reports its own errors, so we don't do so here 1923 1924 return false; 1925 } 1926 } 1927 } 1928 1929 //////////////////////////////////////////////////////////////////////// 1930 // Run function-level passes that only make sense on the main function 1931 // 1932 1933 if (main_function) { 1934 if (!ResolveExternals(*main_function)) { 1935 LLDB_LOG(log, "ResolveExternals() failed"); 1936 1937 // ResolveExternals() reports its own errors, so we don't do so here 1938 1939 return false; 1940 } 1941 1942 if (!ReplaceVariables(*main_function)) { 1943 LLDB_LOG(log, "ReplaceVariables() failed"); 1944 1945 // ReplaceVariables() reports its own errors, so we don't do so here 1946 1947 return false; 1948 } 1949 } 1950 1951 if (log && log->GetVerbose()) { 1952 std::string s; 1953 raw_string_ostream oss(s); 1954 1955 m_module->print(oss, nullptr); 1956 1957 oss.flush(); 1958 1959 LLDB_LOG(log, "Module after preparing for execution: \n\"{0}\"", s); 1960 } 1961 1962 return true; 1963 } 1964