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 #include <optional> 44 45 using namespace llvm; 46 using lldb_private::LLDBLog; 47 48 typedef SmallVector<Instruction *, 2> InstrList; 49 50 IRForTarget::FunctionValueCache::FunctionValueCache(Maker const &maker) 51 : m_maker(maker), m_values() {} 52 53 IRForTarget::FunctionValueCache::~FunctionValueCache() = default; 54 55 llvm::Value * 56 IRForTarget::FunctionValueCache::GetValue(llvm::Function *function) { 57 if (!m_values.count(function)) { 58 llvm::Value *ret = m_maker(function); 59 m_values[function] = ret; 60 return ret; 61 } 62 return m_values[function]; 63 } 64 65 static llvm::Value *FindEntryInstruction(llvm::Function *function) { 66 if (function->empty()) 67 return nullptr; 68 69 return function->getEntryBlock().getFirstNonPHIOrDbg(); 70 } 71 72 IRForTarget::IRForTarget(lldb_private::ClangExpressionDeclMap *decl_map, 73 bool resolve_vars, 74 lldb_private::IRExecutionUnit &execution_unit, 75 lldb_private::Stream &error_stream, 76 const char *func_name) 77 : m_resolve_vars(resolve_vars), m_func_name(func_name), 78 m_decl_map(decl_map), m_error_stream(error_stream), 79 m_execution_unit(execution_unit), 80 m_entry_instruction_finder(FindEntryInstruction) {} 81 82 /* Handy utility functions used at several places in the code */ 83 84 static std::string PrintValue(const Value *value, bool truncate = false) { 85 std::string s; 86 if (value) { 87 raw_string_ostream rso(s); 88 value->print(rso); 89 rso.flush(); 90 if (truncate) 91 s.resize(s.length() - 1); 92 } 93 return s; 94 } 95 96 static std::string PrintType(const llvm::Type *type, bool truncate = false) { 97 std::string s; 98 raw_string_ostream rso(s); 99 type->print(rso); 100 rso.flush(); 101 if (truncate) 102 s.resize(s.length() - 1); 103 return s; 104 } 105 106 bool IRForTarget::FixFunctionLinkage(llvm::Function &llvm_function) { 107 llvm_function.setLinkage(GlobalValue::ExternalLinkage); 108 109 return true; 110 } 111 112 clang::NamedDecl *IRForTarget::DeclForGlobal(const GlobalValue *global_val, 113 Module *module) { 114 NamedMDNode *named_metadata = 115 module->getNamedMetadata("clang.global.decl.ptrs"); 116 117 if (!named_metadata) 118 return nullptr; 119 120 unsigned num_nodes = named_metadata->getNumOperands(); 121 unsigned node_index; 122 123 for (node_index = 0; node_index < num_nodes; ++node_index) { 124 llvm::MDNode *metadata_node = 125 dyn_cast<llvm::MDNode>(named_metadata->getOperand(node_index)); 126 if (!metadata_node) 127 return nullptr; 128 129 if (metadata_node->getNumOperands() != 2) 130 continue; 131 132 if (mdconst::dyn_extract_or_null<GlobalValue>( 133 metadata_node->getOperand(0)) != global_val) 134 continue; 135 136 ConstantInt *constant_int = 137 mdconst::dyn_extract<ConstantInt>(metadata_node->getOperand(1)); 138 139 if (!constant_int) 140 return nullptr; 141 142 uintptr_t ptr = constant_int->getZExtValue(); 143 144 return reinterpret_cast<clang::NamedDecl *>(ptr); 145 } 146 147 return nullptr; 148 } 149 150 clang::NamedDecl *IRForTarget::DeclForGlobal(GlobalValue *global_val) { 151 return DeclForGlobal(global_val, m_module); 152 } 153 154 /// Returns true iff the mangled symbol is for a static guard variable. 155 static bool isGuardVariableSymbol(llvm::StringRef mangled_symbol, 156 bool check_ms_abi = true) { 157 bool result = mangled_symbol.startswith("_ZGV"); // Itanium ABI guard variable 158 if (check_ms_abi) 159 result |= mangled_symbol.endswith("@4IA"); // Microsoft ABI 160 return result; 161 } 162 163 bool IRForTarget::CreateResultVariable(llvm::Function &llvm_function) { 164 lldb_private::Log *log(GetLog(LLDBLog::Expressions)); 165 166 if (!m_resolve_vars) 167 return true; 168 169 // Find the result variable. If it doesn't exist, we can give up right here. 170 171 ValueSymbolTable &value_symbol_table = m_module->getValueSymbolTable(); 172 173 llvm::StringRef result_name; 174 bool found_result = false; 175 176 for (StringMapEntry<llvm::Value *> &value_symbol : value_symbol_table) { 177 result_name = value_symbol.first(); 178 179 // Check if this is a guard variable. It seems this causes some hiccups 180 // on Windows, so let's only check for Itanium guard variables. 181 bool is_guard_var = isGuardVariableSymbol(result_name, /*MS ABI*/ false); 182 183 if (result_name.contains("$__lldb_expr_result_ptr") && !is_guard_var) { 184 found_result = true; 185 m_result_is_pointer = true; 186 break; 187 } 188 189 if (result_name.contains("$__lldb_expr_result") && !is_guard_var) { 190 found_result = true; 191 m_result_is_pointer = false; 192 break; 193 } 194 } 195 196 if (!found_result) { 197 LLDB_LOG(log, "Couldn't find result variable"); 198 199 return true; 200 } 201 202 LLDB_LOG(log, "Result name: \"{0}\"", result_name); 203 204 Value *result_value = m_module->getNamedValue(result_name); 205 206 if (!result_value) { 207 LLDB_LOG(log, "Result variable had no data"); 208 209 m_error_stream.Format("Internal error [IRForTarget]: Result variable's " 210 "name ({0}) exists, but not its definition\n", 211 result_name); 212 213 return false; 214 } 215 216 LLDB_LOG(log, "Found result in the IR: \"{0}\"", 217 PrintValue(result_value, false)); 218 219 GlobalVariable *result_global = dyn_cast<GlobalVariable>(result_value); 220 221 if (!result_global) { 222 LLDB_LOG(log, "Result variable isn't a GlobalVariable"); 223 224 m_error_stream.Format("Internal error [IRForTarget]: Result variable ({0}) " 225 "is defined, but is not a global variable\n", 226 result_name); 227 228 return false; 229 } 230 231 clang::NamedDecl *result_decl = DeclForGlobal(result_global); 232 if (!result_decl) { 233 LLDB_LOG(log, "Result variable doesn't have a corresponding Decl"); 234 235 m_error_stream.Format("Internal error [IRForTarget]: Result variable ({0}) " 236 "does not have a corresponding Clang entity\n", 237 result_name); 238 239 return false; 240 } 241 242 if (log) { 243 std::string decl_desc_str; 244 raw_string_ostream decl_desc_stream(decl_desc_str); 245 result_decl->print(decl_desc_stream); 246 decl_desc_stream.flush(); 247 248 LLDB_LOG(log, "Found result decl: \"{0}\"", decl_desc_str); 249 } 250 251 clang::VarDecl *result_var = dyn_cast<clang::VarDecl>(result_decl); 252 if (!result_var) { 253 LLDB_LOG(log, "Result variable Decl isn't a VarDecl"); 254 255 m_error_stream.Format("Internal error [IRForTarget]: Result variable " 256 "({0})'s corresponding Clang entity isn't a " 257 "variable\n", 258 result_name); 259 260 return false; 261 } 262 263 // Get the next available result name from m_decl_map and create the 264 // persistent variable for it 265 266 // If the result is an Lvalue, it is emitted as a pointer; see 267 // ASTResultSynthesizer::SynthesizeBodyResult. 268 if (m_result_is_pointer) { 269 clang::QualType pointer_qual_type = result_var->getType(); 270 const clang::Type *pointer_type = pointer_qual_type.getTypePtr(); 271 272 const clang::PointerType *pointer_pointertype = 273 pointer_type->getAs<clang::PointerType>(); 274 const clang::ObjCObjectPointerType *pointer_objcobjpointertype = 275 pointer_type->getAs<clang::ObjCObjectPointerType>(); 276 277 if (pointer_pointertype) { 278 clang::QualType element_qual_type = pointer_pointertype->getPointeeType(); 279 280 m_result_type = lldb_private::TypeFromParser( 281 m_decl_map->GetTypeSystem()->GetType(element_qual_type)); 282 } else if (pointer_objcobjpointertype) { 283 clang::QualType element_qual_type = 284 clang::QualType(pointer_objcobjpointertype->getObjectType(), 0); 285 286 m_result_type = lldb_private::TypeFromParser( 287 m_decl_map->GetTypeSystem()->GetType(element_qual_type)); 288 } else { 289 LLDB_LOG(log, "Expected result to have pointer type, but it did not"); 290 291 m_error_stream.Format("Internal error [IRForTarget]: Lvalue result ({0}) " 292 "is not a pointer variable\n", 293 result_name); 294 295 return false; 296 } 297 } else { 298 m_result_type = lldb_private::TypeFromParser( 299 m_decl_map->GetTypeSystem()->GetType(result_var->getType())); 300 } 301 302 lldb::TargetSP target_sp(m_execution_unit.GetTarget()); 303 std::optional<uint64_t> bit_size = m_result_type.GetBitSize(target_sp.get()); 304 if (!bit_size) { 305 lldb_private::StreamString type_desc_stream; 306 m_result_type.DumpTypeDescription(&type_desc_stream); 307 308 LLDB_LOG(log, "Result type has unknown size"); 309 310 m_error_stream.Printf("Error [IRForTarget]: Size of result type '%s' " 311 "couldn't be determined\n", 312 type_desc_stream.GetData()); 313 return false; 314 } 315 316 if (log) { 317 lldb_private::StreamString type_desc_stream; 318 m_result_type.DumpTypeDescription(&type_desc_stream); 319 320 LLDB_LOG(log, "Result decl type: \"{0}\"", type_desc_stream.GetData()); 321 } 322 323 m_result_name = lldb_private::ConstString("$RESULT_NAME"); 324 325 LLDB_LOG(log, "Creating a new result global: \"{0}\" with size {1}", 326 m_result_name, 327 m_result_type.GetByteSize(target_sp.get()).value_or(0)); 328 329 // Construct a new result global and set up its metadata 330 331 GlobalVariable *new_result_global = new GlobalVariable( 332 (*m_module), result_global->getValueType(), false, /* not constant */ 333 GlobalValue::ExternalLinkage, nullptr, /* no initializer */ 334 m_result_name.GetCString()); 335 336 // It's too late in compilation to create a new VarDecl for this, but we 337 // don't need to. We point the metadata at the old VarDecl. This creates an 338 // odd anomaly: a variable with a Value whose name is something like $0 and a 339 // Decl whose name is $__lldb_expr_result. This condition is handled in 340 // ClangExpressionDeclMap::DoMaterialize, and the name of the variable is 341 // fixed up. 342 343 ConstantInt *new_constant_int = 344 ConstantInt::get(llvm::Type::getInt64Ty(m_module->getContext()), 345 reinterpret_cast<uintptr_t>(result_decl), false); 346 347 llvm::Metadata *values[2]; 348 values[0] = ConstantAsMetadata::get(new_result_global); 349 values[1] = ConstantAsMetadata::get(new_constant_int); 350 351 ArrayRef<Metadata *> value_ref(values, 2); 352 353 MDNode *persistent_global_md = MDNode::get(m_module->getContext(), value_ref); 354 NamedMDNode *named_metadata = 355 m_module->getNamedMetadata("clang.global.decl.ptrs"); 356 named_metadata->addOperand(persistent_global_md); 357 358 LLDB_LOG(log, "Replacing \"{0}\" with \"{1}\"", PrintValue(result_global), 359 PrintValue(new_result_global)); 360 361 if (result_global->use_empty()) { 362 // We need to synthesize a store for this variable, because otherwise 363 // there's nothing to put into its equivalent persistent variable. 364 365 BasicBlock &entry_block(llvm_function.getEntryBlock()); 366 Instruction *first_entry_instruction(entry_block.getFirstNonPHIOrDbg()); 367 368 if (!first_entry_instruction) 369 return false; 370 371 if (!result_global->hasInitializer()) { 372 LLDB_LOG(log, "Couldn't find initializer for unused variable"); 373 374 m_error_stream.Format("Internal error [IRForTarget]: Result variable " 375 "({0}) has no writes and no initializer\n", 376 result_name); 377 378 return false; 379 } 380 381 Constant *initializer = result_global->getInitializer(); 382 383 StoreInst *synthesized_store = 384 new StoreInst(initializer, new_result_global, first_entry_instruction); 385 386 LLDB_LOG(log, "Synthesized result store \"{0}\"\n", 387 PrintValue(synthesized_store)); 388 } else { 389 result_global->replaceAllUsesWith(new_result_global); 390 } 391 392 if (!m_decl_map->AddPersistentVariable( 393 result_decl, m_result_name, m_result_type, true, m_result_is_pointer)) 394 return false; 395 396 result_global->eraseFromParent(); 397 398 return true; 399 } 400 401 bool IRForTarget::RewriteObjCConstString(llvm::GlobalVariable *ns_str, 402 llvm::GlobalVariable *cstr) { 403 lldb_private::Log *log(GetLog(LLDBLog::Expressions)); 404 405 Type *ns_str_ty = ns_str->getType(); 406 407 Type *i8_ptr_ty = Type::getInt8PtrTy(m_module->getContext()); 408 Type *i32_ty = Type::getInt32Ty(m_module->getContext()); 409 Type *i8_ty = Type::getInt8Ty(m_module->getContext()); 410 411 if (!m_CFStringCreateWithBytes) { 412 lldb::addr_t CFStringCreateWithBytes_addr; 413 414 static lldb_private::ConstString g_CFStringCreateWithBytes_str( 415 "CFStringCreateWithBytes"); 416 417 bool missing_weak = false; 418 CFStringCreateWithBytes_addr = 419 m_execution_unit.FindSymbol(g_CFStringCreateWithBytes_str, 420 missing_weak); 421 if (CFStringCreateWithBytes_addr == LLDB_INVALID_ADDRESS || missing_weak) { 422 LLDB_LOG(log, "Couldn't find CFStringCreateWithBytes in the target"); 423 424 m_error_stream.Printf("Error [IRForTarget]: Rewriting an Objective-C " 425 "constant string requires " 426 "CFStringCreateWithBytes\n"); 427 428 return false; 429 } 430 431 LLDB_LOG(log, "Found CFStringCreateWithBytes at {0}", 432 CFStringCreateWithBytes_addr); 433 434 // Build the function type: 435 // 436 // CFStringRef CFStringCreateWithBytes ( 437 // CFAllocatorRef alloc, 438 // const UInt8 *bytes, 439 // CFIndex numBytes, 440 // CFStringEncoding encoding, 441 // Boolean isExternalRepresentation 442 // ); 443 // 444 // We make the following substitutions: 445 // 446 // CFStringRef -> i8* 447 // CFAllocatorRef -> i8* 448 // UInt8 * -> i8* 449 // CFIndex -> long (i32 or i64, as appropriate; we ask the module for its 450 // pointer size for now) CFStringEncoding -> i32 Boolean -> i8 451 452 Type *arg_type_array[5]; 453 454 arg_type_array[0] = i8_ptr_ty; 455 arg_type_array[1] = i8_ptr_ty; 456 arg_type_array[2] = m_intptr_ty; 457 arg_type_array[3] = i32_ty; 458 arg_type_array[4] = i8_ty; 459 460 ArrayRef<Type *> CFSCWB_arg_types(arg_type_array, 5); 461 462 llvm::FunctionType *CFSCWB_ty = 463 FunctionType::get(ns_str_ty, CFSCWB_arg_types, false); 464 465 // Build the constant containing the pointer to the function 466 PointerType *CFSCWB_ptr_ty = PointerType::getUnqual(CFSCWB_ty); 467 Constant *CFSCWB_addr_int = 468 ConstantInt::get(m_intptr_ty, CFStringCreateWithBytes_addr, false); 469 m_CFStringCreateWithBytes = { 470 CFSCWB_ty, ConstantExpr::getIntToPtr(CFSCWB_addr_int, CFSCWB_ptr_ty)}; 471 } 472 473 ConstantDataSequential *string_array = nullptr; 474 475 if (cstr) 476 string_array = dyn_cast<ConstantDataSequential>(cstr->getInitializer()); 477 478 Constant *alloc_arg = Constant::getNullValue(i8_ptr_ty); 479 Constant *bytes_arg = cstr ? cstr : 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_METH_VAR_NAME_". 746 // @"\01L_OBJC_METH_VAR_NAME_" 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 CallInst *srN_call = 824 CallInst::Create(m_sel_registerName, _objc_meth_var_name_, 825 "sel_registerName", selector_load); 826 827 // Replace the load with the call in all users 828 829 selector_load->replaceAllUsesWith(srN_call); 830 831 selector_load->eraseFromParent(); 832 833 return true; 834 } 835 836 bool IRForTarget::RewriteObjCSelectors(BasicBlock &basic_block) { 837 lldb_private::Log *log(GetLog(LLDBLog::Expressions)); 838 839 InstrList selector_loads; 840 841 for (Instruction &inst : basic_block) { 842 if (LoadInst *load = dyn_cast<LoadInst>(&inst)) 843 if (IsObjCSelectorRef(load->getPointerOperand())) 844 selector_loads.push_back(&inst); 845 } 846 847 for (Instruction *inst : selector_loads) { 848 if (!RewriteObjCSelector(inst)) { 849 m_error_stream.Printf("Internal error [IRForTarget]: Couldn't change a " 850 "static reference to an Objective-C selector to a " 851 "dynamic reference\n"); 852 853 LLDB_LOG(log, "Couldn't rewrite a reference to an Objective-C selector"); 854 855 return false; 856 } 857 } 858 859 return true; 860 } 861 862 // This function does not report errors; its callers are responsible. 863 bool IRForTarget::RewritePersistentAlloc(llvm::Instruction *persistent_alloc) { 864 lldb_private::Log *log(GetLog(LLDBLog::Expressions)); 865 866 AllocaInst *alloc = dyn_cast<AllocaInst>(persistent_alloc); 867 868 MDNode *alloc_md = alloc->getMetadata("clang.decl.ptr"); 869 870 if (!alloc_md || !alloc_md->getNumOperands()) 871 return false; 872 873 ConstantInt *constant_int = 874 mdconst::dyn_extract<ConstantInt>(alloc_md->getOperand(0)); 875 876 if (!constant_int) 877 return false; 878 879 // We attempt to register this as a new persistent variable with the DeclMap. 880 881 uintptr_t ptr = constant_int->getZExtValue(); 882 883 clang::VarDecl *decl = reinterpret_cast<clang::VarDecl *>(ptr); 884 885 lldb_private::TypeFromParser result_decl_type( 886 m_decl_map->GetTypeSystem()->GetType(decl->getType())); 887 888 StringRef decl_name(decl->getName()); 889 lldb_private::ConstString persistent_variable_name(decl_name.data(), 890 decl_name.size()); 891 if (!m_decl_map->AddPersistentVariable(decl, persistent_variable_name, 892 result_decl_type, false, false)) 893 return false; 894 895 GlobalVariable *persistent_global = new GlobalVariable( 896 (*m_module), alloc->getType(), false, /* not constant */ 897 GlobalValue::ExternalLinkage, nullptr, /* no initializer */ 898 alloc->getName().str()); 899 900 // What we're going to do here is make believe this was a regular old 901 // external variable. That means we need to make the metadata valid. 902 903 NamedMDNode *named_metadata = 904 m_module->getOrInsertNamedMetadata("clang.global.decl.ptrs"); 905 906 llvm::Metadata *values[2]; 907 values[0] = ConstantAsMetadata::get(persistent_global); 908 values[1] = ConstantAsMetadata::get(constant_int); 909 910 ArrayRef<llvm::Metadata *> value_ref(values, 2); 911 912 MDNode *persistent_global_md = MDNode::get(m_module->getContext(), value_ref); 913 named_metadata->addOperand(persistent_global_md); 914 915 // Now, since the variable is a pointer variable, we will drop in a load of 916 // that pointer variable. 917 918 LoadInst *persistent_load = new LoadInst(persistent_global->getValueType(), 919 persistent_global, "", alloc); 920 921 LLDB_LOG(log, "Replacing \"{0}\" with \"{1}\"", PrintValue(alloc), 922 PrintValue(persistent_load)); 923 924 alloc->replaceAllUsesWith(persistent_load); 925 alloc->eraseFromParent(); 926 927 return true; 928 } 929 930 bool IRForTarget::RewritePersistentAllocs(llvm::BasicBlock &basic_block) { 931 if (!m_resolve_vars) 932 return true; 933 934 lldb_private::Log *log(GetLog(LLDBLog::Expressions)); 935 936 InstrList pvar_allocs; 937 938 for (Instruction &inst : basic_block) { 939 940 if (AllocaInst *alloc = dyn_cast<AllocaInst>(&inst)) { 941 llvm::StringRef alloc_name = alloc->getName(); 942 943 if (alloc_name.startswith("$") && !alloc_name.startswith("$__lldb")) { 944 if (alloc_name.find_first_of("0123456789") == 1) { 945 LLDB_LOG(log, "Rejecting a numeric persistent variable."); 946 947 m_error_stream.Printf("Error [IRForTarget]: Names starting with $0, " 948 "$1, ... are reserved for use as result " 949 "names\n"); 950 951 return false; 952 } 953 954 pvar_allocs.push_back(alloc); 955 } 956 } 957 } 958 959 for (Instruction *inst : pvar_allocs) { 960 if (!RewritePersistentAlloc(inst)) { 961 m_error_stream.Printf("Internal error [IRForTarget]: Couldn't rewrite " 962 "the creation of a persistent variable\n"); 963 964 LLDB_LOG(log, "Couldn't rewrite the creation of a persistent variable"); 965 966 return false; 967 } 968 } 969 970 return true; 971 } 972 973 // This function does not report errors; its callers are responsible. 974 bool IRForTarget::MaybeHandleVariable(Value *llvm_value_ptr) { 975 lldb_private::Log *log(GetLog(LLDBLog::Expressions)); 976 977 LLDB_LOG(log, "MaybeHandleVariable ({0})", PrintValue(llvm_value_ptr)); 978 979 if (ConstantExpr *constant_expr = dyn_cast<ConstantExpr>(llvm_value_ptr)) { 980 switch (constant_expr->getOpcode()) { 981 default: 982 break; 983 case Instruction::GetElementPtr: 984 case Instruction::BitCast: 985 Value *s = constant_expr->getOperand(0); 986 if (!MaybeHandleVariable(s)) 987 return false; 988 } 989 } else if (GlobalVariable *global_variable = 990 dyn_cast<GlobalVariable>(llvm_value_ptr)) { 991 if (!GlobalValue::isExternalLinkage(global_variable->getLinkage())) 992 return true; 993 994 clang::NamedDecl *named_decl = DeclForGlobal(global_variable); 995 996 if (!named_decl) { 997 if (IsObjCSelectorRef(llvm_value_ptr)) 998 return true; 999 1000 if (!global_variable->hasExternalLinkage()) 1001 return true; 1002 1003 LLDB_LOG(log, "Found global variable \"{0}\" without metadata", 1004 global_variable->getName()); 1005 1006 return false; 1007 } 1008 1009 llvm::StringRef name(named_decl->getName()); 1010 1011 clang::ValueDecl *value_decl = dyn_cast<clang::ValueDecl>(named_decl); 1012 if (value_decl == nullptr) 1013 return false; 1014 1015 lldb_private::CompilerType compiler_type = 1016 m_decl_map->GetTypeSystem()->GetType(value_decl->getType()); 1017 1018 const Type *value_type = nullptr; 1019 1020 if (name.startswith("$")) { 1021 // The $__lldb_expr_result name indicates the return value has allocated 1022 // as a static variable. Per the comment at 1023 // ASTResultSynthesizer::SynthesizeBodyResult, accesses to this static 1024 // variable need to be redirected to the result of dereferencing a 1025 // pointer that is passed in as one of the arguments. 1026 // 1027 // Consequently, when reporting the size of the type, we report a pointer 1028 // type pointing to the type of $__lldb_expr_result, not the type itself. 1029 // 1030 // We also do this for any user-declared persistent variables. 1031 compiler_type = compiler_type.GetPointerType(); 1032 value_type = PointerType::get(global_variable->getType(), 0); 1033 } else { 1034 value_type = global_variable->getType(); 1035 } 1036 1037 auto *target = m_execution_unit.GetTarget().get(); 1038 std::optional<uint64_t> value_size = compiler_type.GetByteSize(target); 1039 if (!value_size) 1040 return false; 1041 std::optional<size_t> opt_alignment = compiler_type.GetTypeBitAlign(target); 1042 if (!opt_alignment) 1043 return false; 1044 lldb::offset_t value_alignment = (*opt_alignment + 7ull) / 8ull; 1045 1046 LLDB_LOG(log, 1047 "Type of \"{0}\" is [clang \"{1}\", llvm \"{2}\"] [size {3}, " 1048 "align {4}]", 1049 name, 1050 lldb_private::ClangUtil::GetQualType(compiler_type).getAsString(), 1051 PrintType(value_type), *value_size, value_alignment); 1052 1053 if (named_decl) 1054 m_decl_map->AddValueToStruct(named_decl, lldb_private::ConstString(name), 1055 llvm_value_ptr, *value_size, 1056 value_alignment); 1057 } else if (isa<llvm::Function>(llvm_value_ptr)) { 1058 LLDB_LOG(log, "Function pointers aren't handled right now"); 1059 1060 return false; 1061 } 1062 1063 return true; 1064 } 1065 1066 // This function does not report errors; its callers are responsible. 1067 bool IRForTarget::HandleSymbol(Value *symbol) { 1068 lldb_private::Log *log(GetLog(LLDBLog::Expressions)); 1069 1070 lldb_private::ConstString name(symbol->getName().str().c_str()); 1071 1072 lldb::addr_t symbol_addr = 1073 m_decl_map->GetSymbolAddress(name, lldb::eSymbolTypeAny); 1074 1075 if (symbol_addr == LLDB_INVALID_ADDRESS) { 1076 LLDB_LOG(log, "Symbol \"{0}\" had no address", name); 1077 1078 return false; 1079 } 1080 1081 LLDB_LOG(log, "Found \"{0}\" at {1}", name, symbol_addr); 1082 1083 Type *symbol_type = symbol->getType(); 1084 1085 Constant *symbol_addr_int = ConstantInt::get(m_intptr_ty, symbol_addr, false); 1086 1087 Value *symbol_addr_ptr = 1088 ConstantExpr::getIntToPtr(symbol_addr_int, symbol_type); 1089 1090 LLDB_LOG(log, "Replacing {0} with {1}", PrintValue(symbol), 1091 PrintValue(symbol_addr_ptr)); 1092 1093 symbol->replaceAllUsesWith(symbol_addr_ptr); 1094 1095 return true; 1096 } 1097 1098 bool IRForTarget::MaybeHandleCallArguments(CallInst *Old) { 1099 lldb_private::Log *log(GetLog(LLDBLog::Expressions)); 1100 1101 LLDB_LOG(log, "MaybeHandleCallArguments({0})", PrintValue(Old)); 1102 1103 for (unsigned op_index = 0, num_ops = Old->arg_size(); 1104 op_index < num_ops; ++op_index) 1105 // conservatively believe that this is a store 1106 if (!MaybeHandleVariable(Old->getArgOperand(op_index))) { 1107 m_error_stream.Printf("Internal error [IRForTarget]: Couldn't rewrite " 1108 "one of the arguments of a function call.\n"); 1109 1110 return false; 1111 } 1112 1113 return true; 1114 } 1115 1116 bool IRForTarget::HandleObjCClass(Value *classlist_reference) { 1117 lldb_private::Log *log(GetLog(LLDBLog::Expressions)); 1118 1119 GlobalVariable *global_variable = 1120 dyn_cast<GlobalVariable>(classlist_reference); 1121 1122 if (!global_variable) 1123 return false; 1124 1125 Constant *initializer = global_variable->getInitializer(); 1126 1127 if (!initializer) 1128 return false; 1129 1130 if (!initializer->hasName()) 1131 return false; 1132 1133 StringRef name(initializer->getName()); 1134 lldb_private::ConstString name_cstr(name.str().c_str()); 1135 lldb::addr_t class_ptr = 1136 m_decl_map->GetSymbolAddress(name_cstr, lldb::eSymbolTypeObjCClass); 1137 1138 LLDB_LOG(log, "Found reference to Objective-C class {0} ({1})", name, 1139 (unsigned long long)class_ptr); 1140 1141 if (class_ptr == LLDB_INVALID_ADDRESS) 1142 return false; 1143 1144 if (global_variable->use_empty()) 1145 return false; 1146 1147 SmallVector<LoadInst *, 2> load_instructions; 1148 1149 for (llvm::User *u : global_variable->users()) { 1150 if (LoadInst *load_instruction = dyn_cast<LoadInst>(u)) 1151 load_instructions.push_back(load_instruction); 1152 } 1153 1154 if (load_instructions.empty()) 1155 return false; 1156 1157 Constant *class_addr = ConstantInt::get(m_intptr_ty, (uint64_t)class_ptr); 1158 1159 for (LoadInst *load_instruction : load_instructions) { 1160 Constant *class_bitcast = 1161 ConstantExpr::getIntToPtr(class_addr, load_instruction->getType()); 1162 1163 load_instruction->replaceAllUsesWith(class_bitcast); 1164 1165 load_instruction->eraseFromParent(); 1166 } 1167 1168 return true; 1169 } 1170 1171 bool IRForTarget::RemoveCXAAtExit(BasicBlock &basic_block) { 1172 std::vector<CallInst *> calls_to_remove; 1173 1174 for (Instruction &inst : basic_block) { 1175 CallInst *call = dyn_cast<CallInst>(&inst); 1176 1177 // MaybeHandleCallArguments handles error reporting; we are silent here 1178 if (!call) 1179 continue; 1180 1181 bool remove = false; 1182 1183 llvm::Function *func = call->getCalledFunction(); 1184 1185 if (func && func->getName() == "__cxa_atexit") 1186 remove = true; 1187 1188 llvm::Value *val = call->getCalledOperand(); 1189 1190 if (val && val->getName() == "__cxa_atexit") 1191 remove = true; 1192 1193 if (remove) 1194 calls_to_remove.push_back(call); 1195 } 1196 1197 for (CallInst *ci : calls_to_remove) 1198 ci->eraseFromParent(); 1199 1200 return true; 1201 } 1202 1203 bool IRForTarget::ResolveCalls(BasicBlock &basic_block) { 1204 // Prepare the current basic block for execution in the remote process 1205 1206 for (Instruction &inst : basic_block) { 1207 CallInst *call = dyn_cast<CallInst>(&inst); 1208 1209 // MaybeHandleCallArguments handles error reporting; we are silent here 1210 if (call && !MaybeHandleCallArguments(call)) 1211 return false; 1212 } 1213 1214 return true; 1215 } 1216 1217 bool IRForTarget::ResolveExternals(Function &llvm_function) { 1218 lldb_private::Log *log(GetLog(LLDBLog::Expressions)); 1219 1220 for (GlobalVariable &global_var : m_module->globals()) { 1221 llvm::StringRef global_name = global_var.getName(); 1222 1223 LLDB_LOG(log, "Examining {0}, DeclForGlobalValue returns {1}", global_name, 1224 static_cast<void *>(DeclForGlobal(&global_var))); 1225 1226 if (global_name.startswith("OBJC_IVAR")) { 1227 if (!HandleSymbol(&global_var)) { 1228 m_error_stream.Format("Error [IRForTarget]: Couldn't find Objective-C " 1229 "indirect ivar symbol {0}\n", 1230 global_name); 1231 1232 return false; 1233 } 1234 } else if (global_name.contains("OBJC_CLASSLIST_REFERENCES_$")) { 1235 if (!HandleObjCClass(&global_var)) { 1236 m_error_stream.Printf("Error [IRForTarget]: Couldn't resolve the class " 1237 "for an Objective-C static method call\n"); 1238 1239 return false; 1240 } 1241 } else if (global_name.contains("OBJC_CLASSLIST_SUP_REFS_$")) { 1242 if (!HandleObjCClass(&global_var)) { 1243 m_error_stream.Printf("Error [IRForTarget]: Couldn't resolve the class " 1244 "for an Objective-C static method call\n"); 1245 1246 return false; 1247 } 1248 } else if (DeclForGlobal(&global_var)) { 1249 if (!MaybeHandleVariable(&global_var)) { 1250 m_error_stream.Format("Internal error [IRForTarget]: Couldn't rewrite " 1251 "external variable {0}\n", 1252 global_name); 1253 1254 return false; 1255 } 1256 } 1257 } 1258 1259 return true; 1260 } 1261 1262 static bool isGuardVariableRef(Value *V) { 1263 GlobalVariable *GV = dyn_cast<GlobalVariable>(V); 1264 1265 if (!GV || !GV->hasName() || !isGuardVariableSymbol(GV->getName())) 1266 return false; 1267 1268 return true; 1269 } 1270 1271 void IRForTarget::TurnGuardLoadIntoZero(llvm::Instruction *guard_load) { 1272 Constant *zero(Constant::getNullValue(guard_load->getType())); 1273 guard_load->replaceAllUsesWith(zero); 1274 guard_load->eraseFromParent(); 1275 } 1276 1277 static void ExciseGuardStore(Instruction *guard_store) { 1278 guard_store->eraseFromParent(); 1279 } 1280 1281 bool IRForTarget::RemoveGuards(BasicBlock &basic_block) { 1282 // Eliminate any reference to guard variables found. 1283 1284 InstrList guard_loads; 1285 InstrList guard_stores; 1286 1287 for (Instruction &inst : basic_block) { 1288 1289 if (LoadInst *load = dyn_cast<LoadInst>(&inst)) 1290 if (isGuardVariableRef(load->getPointerOperand())) 1291 guard_loads.push_back(&inst); 1292 1293 if (StoreInst *store = dyn_cast<StoreInst>(&inst)) 1294 if (isGuardVariableRef(store->getPointerOperand())) 1295 guard_stores.push_back(&inst); 1296 } 1297 1298 for (Instruction *inst : guard_loads) 1299 TurnGuardLoadIntoZero(inst); 1300 1301 for (Instruction *inst : guard_stores) 1302 ExciseGuardStore(inst); 1303 1304 return true; 1305 } 1306 1307 // This function does not report errors; its callers are responsible. 1308 bool IRForTarget::UnfoldConstant(Constant *old_constant, 1309 llvm::Function *llvm_function, 1310 FunctionValueCache &value_maker, 1311 FunctionValueCache &entry_instruction_finder, 1312 lldb_private::Stream &error_stream) { 1313 SmallVector<User *, 16> users; 1314 1315 // We do this because the use list might change, invalidating our iterator. 1316 // Much better to keep a work list ourselves. 1317 for (llvm::User *u : old_constant->users()) 1318 users.push_back(u); 1319 1320 for (size_t i = 0; i < users.size(); ++i) { 1321 User *user = users[i]; 1322 1323 if (Constant *constant = dyn_cast<Constant>(user)) { 1324 // synthesize a new non-constant equivalent of the constant 1325 1326 if (ConstantExpr *constant_expr = dyn_cast<ConstantExpr>(constant)) { 1327 switch (constant_expr->getOpcode()) { 1328 default: 1329 error_stream.Printf("error [IRForTarget internal]: Unhandled " 1330 "constant expression type: \"%s\"", 1331 PrintValue(constant_expr).c_str()); 1332 return false; 1333 case Instruction::BitCast: { 1334 FunctionValueCache bit_cast_maker( 1335 [&value_maker, &entry_instruction_finder, old_constant, 1336 constant_expr](llvm::Function *function) -> llvm::Value * { 1337 // UnaryExpr 1338 // OperandList[0] is value 1339 1340 if (constant_expr->getOperand(0) != old_constant) 1341 return constant_expr; 1342 1343 return new BitCastInst( 1344 value_maker.GetValue(function), constant_expr->getType(), 1345 "", llvm::cast<Instruction>( 1346 entry_instruction_finder.GetValue(function))); 1347 }); 1348 1349 if (!UnfoldConstant(constant_expr, llvm_function, bit_cast_maker, 1350 entry_instruction_finder, error_stream)) 1351 return false; 1352 } break; 1353 case Instruction::GetElementPtr: { 1354 // GetElementPtrConstantExpr 1355 // OperandList[0] is base 1356 // OperandList[1]... are indices 1357 1358 FunctionValueCache get_element_pointer_maker( 1359 [&value_maker, &entry_instruction_finder, old_constant, 1360 constant_expr](llvm::Function *function) -> llvm::Value * { 1361 auto *gep = cast<llvm::GEPOperator>(constant_expr); 1362 Value *ptr = gep->getPointerOperand(); 1363 1364 if (ptr == old_constant) 1365 ptr = value_maker.GetValue(function); 1366 1367 std::vector<Value *> index_vector; 1368 for (Value *operand : gep->indices()) { 1369 if (operand == old_constant) 1370 operand = value_maker.GetValue(function); 1371 1372 index_vector.push_back(operand); 1373 } 1374 1375 ArrayRef<Value *> indices(index_vector); 1376 1377 return GetElementPtrInst::Create( 1378 gep->getSourceElementType(), ptr, indices, "", 1379 llvm::cast<Instruction>( 1380 entry_instruction_finder.GetValue(function))); 1381 }); 1382 1383 if (!UnfoldConstant(constant_expr, llvm_function, 1384 get_element_pointer_maker, 1385 entry_instruction_finder, error_stream)) 1386 return false; 1387 } break; 1388 } 1389 } else { 1390 error_stream.Printf( 1391 "error [IRForTarget internal]: Unhandled constant type: \"%s\"", 1392 PrintValue(constant).c_str()); 1393 return false; 1394 } 1395 } else { 1396 if (Instruction *inst = llvm::dyn_cast<Instruction>(user)) { 1397 if (llvm_function && inst->getParent()->getParent() != llvm_function) { 1398 error_stream.PutCString("error: Capturing non-local variables in " 1399 "expressions is unsupported.\n"); 1400 return false; 1401 } 1402 inst->replaceUsesOfWith( 1403 old_constant, value_maker.GetValue(inst->getParent()->getParent())); 1404 } else { 1405 error_stream.Printf( 1406 "error [IRForTarget internal]: Unhandled non-constant type: \"%s\"", 1407 PrintValue(user).c_str()); 1408 return false; 1409 } 1410 } 1411 } 1412 1413 if (!isa<GlobalValue>(old_constant)) { 1414 old_constant->destroyConstant(); 1415 } 1416 1417 return true; 1418 } 1419 1420 bool IRForTarget::ReplaceVariables(Function &llvm_function) { 1421 if (!m_resolve_vars) 1422 return true; 1423 1424 lldb_private::Log *log(GetLog(LLDBLog::Expressions)); 1425 1426 m_decl_map->DoStructLayout(); 1427 1428 LLDB_LOG(log, "Element arrangement:"); 1429 1430 uint32_t num_elements; 1431 uint32_t element_index; 1432 1433 size_t size; 1434 lldb::offset_t alignment; 1435 1436 if (!m_decl_map->GetStructInfo(num_elements, size, alignment)) 1437 return false; 1438 1439 Function::arg_iterator iter(llvm_function.arg_begin()); 1440 1441 if (iter == llvm_function.arg_end()) { 1442 m_error_stream.Printf("Internal error [IRForTarget]: Wrapper takes no " 1443 "arguments (should take at least a struct pointer)"); 1444 1445 return false; 1446 } 1447 1448 Argument *argument = &*iter; 1449 1450 if (argument->getName().equals("this")) { 1451 ++iter; 1452 1453 if (iter == llvm_function.arg_end()) { 1454 m_error_stream.Printf("Internal error [IRForTarget]: Wrapper takes only " 1455 "'this' argument (should take a struct pointer " 1456 "too)"); 1457 1458 return false; 1459 } 1460 1461 argument = &*iter; 1462 } else if (argument->getName().equals("self")) { 1463 ++iter; 1464 1465 if (iter == llvm_function.arg_end()) { 1466 m_error_stream.Printf("Internal error [IRForTarget]: Wrapper takes only " 1467 "'self' argument (should take '_cmd' and a struct " 1468 "pointer too)"); 1469 1470 return false; 1471 } 1472 1473 if (!iter->getName().equals("_cmd")) { 1474 m_error_stream.Format("Internal error [IRForTarget]: Wrapper takes '{0}' " 1475 "after 'self' argument (should take '_cmd')", 1476 iter->getName()); 1477 1478 return false; 1479 } 1480 1481 ++iter; 1482 1483 if (iter == llvm_function.arg_end()) { 1484 m_error_stream.Printf("Internal error [IRForTarget]: Wrapper takes only " 1485 "'self' and '_cmd' arguments (should take a struct " 1486 "pointer too)"); 1487 1488 return false; 1489 } 1490 1491 argument = &*iter; 1492 } 1493 1494 if (!argument->getName().equals("$__lldb_arg")) { 1495 m_error_stream.Format("Internal error [IRForTarget]: Wrapper takes an " 1496 "argument named '{0}' instead of the struct pointer", 1497 argument->getName()); 1498 1499 return false; 1500 } 1501 1502 LLDB_LOG(log, "Arg: \"{0}\"", PrintValue(argument)); 1503 1504 BasicBlock &entry_block(llvm_function.getEntryBlock()); 1505 Instruction *FirstEntryInstruction(entry_block.getFirstNonPHIOrDbg()); 1506 1507 if (!FirstEntryInstruction) { 1508 m_error_stream.Printf("Internal error [IRForTarget]: Couldn't find the " 1509 "first instruction in the wrapper for use in " 1510 "rewriting"); 1511 1512 return false; 1513 } 1514 1515 LLVMContext &context(m_module->getContext()); 1516 IntegerType *offset_type(Type::getInt32Ty(context)); 1517 1518 if (!offset_type) { 1519 m_error_stream.Printf( 1520 "Internal error [IRForTarget]: Couldn't produce an offset type"); 1521 1522 return false; 1523 } 1524 1525 for (element_index = 0; element_index < num_elements; ++element_index) { 1526 const clang::NamedDecl *decl = nullptr; 1527 Value *value = nullptr; 1528 lldb::offset_t offset; 1529 lldb_private::ConstString name; 1530 1531 if (!m_decl_map->GetStructElement(decl, value, offset, name, 1532 element_index)) { 1533 m_error_stream.Printf( 1534 "Internal error [IRForTarget]: Structure information is incomplete"); 1535 1536 return false; 1537 } 1538 1539 LLDB_LOG(log, " \"{0}\" (\"{1}\") placed at {2}", name, 1540 decl->getNameAsString(), offset); 1541 1542 if (value) { 1543 LLDB_LOG(log, " Replacing [{0}]", PrintValue(value)); 1544 1545 FunctionValueCache body_result_maker( 1546 [this, name, offset_type, offset, argument, 1547 value](llvm::Function *function) -> llvm::Value * { 1548 // Per the comment at ASTResultSynthesizer::SynthesizeBodyResult, 1549 // in cases where the result variable is an rvalue, we have to 1550 // synthesize a dereference of the appropriate structure entry in 1551 // order to produce the static variable that the AST thinks it is 1552 // accessing. 1553 1554 llvm::Instruction *entry_instruction = llvm::cast<Instruction>( 1555 m_entry_instruction_finder.GetValue(function)); 1556 1557 Type *int8Ty = Type::getInt8Ty(function->getContext()); 1558 ConstantInt *offset_int( 1559 ConstantInt::get(offset_type, offset, true)); 1560 GetElementPtrInst *get_element_ptr = GetElementPtrInst::Create( 1561 int8Ty, argument, offset_int, "", entry_instruction); 1562 1563 if (name == m_result_name && !m_result_is_pointer) { 1564 LoadInst *load = new LoadInst(value->getType(), get_element_ptr, 1565 "", entry_instruction); 1566 1567 return load; 1568 } else { 1569 return get_element_ptr; 1570 } 1571 }); 1572 1573 if (Constant *constant = dyn_cast<Constant>(value)) { 1574 if (!UnfoldConstant(constant, &llvm_function, body_result_maker, 1575 m_entry_instruction_finder, m_error_stream)) { 1576 return false; 1577 } 1578 } else if (Instruction *instruction = dyn_cast<Instruction>(value)) { 1579 if (instruction->getParent()->getParent() != &llvm_function) { 1580 m_error_stream.PutCString("error: Capturing non-local variables in " 1581 "expressions is unsupported.\n"); 1582 return false; 1583 } 1584 value->replaceAllUsesWith( 1585 body_result_maker.GetValue(instruction->getParent()->getParent())); 1586 } else { 1587 LLDB_LOG(log, "Unhandled non-constant type: \"{0}\"", 1588 PrintValue(value)); 1589 return false; 1590 } 1591 1592 if (GlobalVariable *var = dyn_cast<GlobalVariable>(value)) 1593 var->eraseFromParent(); 1594 } 1595 } 1596 1597 LLDB_LOG(log, "Total structure [align {0}, size {1}]", (int64_t)alignment, 1598 (uint64_t)size); 1599 1600 return true; 1601 } 1602 1603 bool IRForTarget::runOnModule(Module &llvm_module) { 1604 lldb_private::Log *log(GetLog(LLDBLog::Expressions)); 1605 1606 m_module = &llvm_module; 1607 m_target_data = std::make_unique<DataLayout>(m_module); 1608 m_intptr_ty = llvm::Type::getIntNTy(m_module->getContext(), 1609 m_target_data->getPointerSizeInBits()); 1610 1611 if (log) { 1612 std::string s; 1613 raw_string_ostream oss(s); 1614 1615 m_module->print(oss, nullptr); 1616 1617 oss.flush(); 1618 1619 LLDB_LOG(log, "Module as passed in to IRForTarget: \n\"{0}\"", s); 1620 } 1621 1622 Function *const main_function = 1623 m_func_name.IsEmpty() ? nullptr 1624 : m_module->getFunction(m_func_name.GetStringRef()); 1625 1626 if (!m_func_name.IsEmpty() && !main_function) { 1627 LLDB_LOG(log, "Couldn't find \"{0}()\" in the module", m_func_name); 1628 1629 m_error_stream.Format("Internal error [IRForTarget]: Couldn't find wrapper " 1630 "'{0}' in the module", 1631 m_func_name); 1632 1633 return false; 1634 } 1635 1636 if (main_function) { 1637 if (!FixFunctionLinkage(*main_function)) { 1638 LLDB_LOG(log, "Couldn't fix the linkage for the function"); 1639 1640 return false; 1641 } 1642 } 1643 1644 llvm::Type *int8_ty = Type::getInt8Ty(m_module->getContext()); 1645 1646 m_reloc_placeholder = new llvm::GlobalVariable( 1647 (*m_module), int8_ty, false /* IsConstant */, 1648 GlobalVariable::InternalLinkage, Constant::getNullValue(int8_ty), 1649 "reloc_placeholder", nullptr /* InsertBefore */, 1650 GlobalVariable::NotThreadLocal /* ThreadLocal */, 0 /* AddressSpace */); 1651 1652 //////////////////////////////////////////////////////////// 1653 // Replace $__lldb_expr_result with a persistent variable 1654 // 1655 1656 if (main_function) { 1657 if (!CreateResultVariable(*main_function)) { 1658 LLDB_LOG(log, "CreateResultVariable() failed"); 1659 1660 // CreateResultVariable() reports its own errors, so we don't do so here 1661 1662 return false; 1663 } 1664 } 1665 1666 if (log && log->GetVerbose()) { 1667 std::string s; 1668 raw_string_ostream oss(s); 1669 1670 m_module->print(oss, nullptr); 1671 1672 oss.flush(); 1673 1674 LLDB_LOG(log, "Module after creating the result variable: \n\"{0}\"", s); 1675 } 1676 1677 for (llvm::Function &function : *m_module) { 1678 for (BasicBlock &bb : function) { 1679 if (!RemoveGuards(bb)) { 1680 LLDB_LOG(log, "RemoveGuards() failed"); 1681 1682 // RemoveGuards() reports its own errors, so we don't do so here 1683 1684 return false; 1685 } 1686 1687 if (!RewritePersistentAllocs(bb)) { 1688 LLDB_LOG(log, "RewritePersistentAllocs() failed"); 1689 1690 // RewritePersistentAllocs() reports its own errors, so we don't do so 1691 // here 1692 1693 return false; 1694 } 1695 1696 if (!RemoveCXAAtExit(bb)) { 1697 LLDB_LOG(log, "RemoveCXAAtExit() failed"); 1698 1699 // RemoveCXAAtExit() reports its own errors, so we don't do so here 1700 1701 return false; 1702 } 1703 } 1704 } 1705 1706 /////////////////////////////////////////////////////////////////////////////// 1707 // Fix all Objective-C constant strings to use NSStringWithCString:encoding: 1708 // 1709 1710 if (!RewriteObjCConstStrings()) { 1711 LLDB_LOG(log, "RewriteObjCConstStrings() failed"); 1712 1713 // RewriteObjCConstStrings() reports its own errors, so we don't do so here 1714 1715 return false; 1716 } 1717 1718 for (llvm::Function &function : *m_module) { 1719 for (llvm::BasicBlock &bb : function) { 1720 if (!RewriteObjCSelectors(bb)) { 1721 LLDB_LOG(log, "RewriteObjCSelectors() failed"); 1722 1723 // RewriteObjCSelectors() reports its own errors, so we don't do so 1724 // here 1725 1726 return false; 1727 } 1728 } 1729 } 1730 1731 for (llvm::Function &function : *m_module) { 1732 for (BasicBlock &bb : function) { 1733 if (!ResolveCalls(bb)) { 1734 LLDB_LOG(log, "ResolveCalls() failed"); 1735 1736 // ResolveCalls() reports its own errors, so we don't do so here 1737 1738 return false; 1739 } 1740 } 1741 } 1742 1743 //////////////////////////////////////////////////////////////////////// 1744 // Run function-level passes that only make sense on the main function 1745 // 1746 1747 if (main_function) { 1748 if (!ResolveExternals(*main_function)) { 1749 LLDB_LOG(log, "ResolveExternals() failed"); 1750 1751 // ResolveExternals() reports its own errors, so we don't do so here 1752 1753 return false; 1754 } 1755 1756 if (!ReplaceVariables(*main_function)) { 1757 LLDB_LOG(log, "ReplaceVariables() failed"); 1758 1759 // ReplaceVariables() reports its own errors, so we don't do so here 1760 1761 return false; 1762 } 1763 } 1764 1765 if (log && log->GetVerbose()) { 1766 std::string s; 1767 raw_string_ostream oss(s); 1768 1769 m_module->print(oss, nullptr); 1770 1771 oss.flush(); 1772 1773 LLDB_LOG(log, "Module after preparing for execution: \n\"{0}\"", s); 1774 } 1775 1776 return true; 1777 } 1778