lldb/source/Expression/UserExpression.cpp

   1 //===-- UserExpression.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 <cstdio>
  10 #include <sys/types.h>
  11
  12 #include <cstdlib>
  13 #include <map>
  14 #include <string>
  15
  16 #include "lldb/Core/Module.h"
  17 #include "lldb/Core/Progress.h"
  18 #include "lldb/Expression/DiagnosticManager.h"
  19 #include "lldb/Expression/ExpressionVariable.h"
  20 #include "lldb/Expression/IRExecutionUnit.h"
  21 #include "lldb/Expression/IRInterpreter.h"
  22 #include "lldb/Expression/Materializer.h"
  23 #include "lldb/Expression/UserExpression.h"
  24 #include "lldb/Host/HostInfo.h"
  25 #include "lldb/Symbol/Block.h"
  26 #include "lldb/Symbol/Function.h"
  27 #include "lldb/Symbol/ObjectFile.h"
  28 #include "lldb/Symbol/SymbolVendor.h"
  29 #include "lldb/Symbol/Type.h"
  30 #include "lldb/Symbol/TypeSystem.h"
  31 #include "lldb/Symbol/VariableList.h"
  32 #include "lldb/Target/ExecutionContext.h"
  33 #include "lldb/Target/Process.h"
  34 #include "lldb/Target/StackFrame.h"
  35 #include "lldb/Target/Target.h"
  36 #include "lldb/Target/ThreadPlan.h"
  37 #include "lldb/Target/ThreadPlanCallUserExpression.h"
  38 #include "lldb/Utility/LLDBLog.h"
  39 #include "lldb/Utility/Log.h"
  40 #include "lldb/Utility/State.h"
  41 #include "lldb/Utility/StreamString.h"
  42 #include "lldb/ValueObject/ValueObjectConstResult.h"
  43 #include "llvm/BinaryFormat/Dwarf.h"
  44
  45 using namespace lldb_private;
  46
  47 char UserExpression::ID;
  48
  49 UserExpression::UserExpression(ExecutionContextScope &exe_scope,
  50                                llvm::StringRef expr, llvm::StringRef prefix,
  51                                SourceLanguage language, ResultType desired_type,
  52                                const EvaluateExpressionOptions &options)
  53     : Expression(exe_scope), m_expr_text(std::string(expr)),
  54       m_expr_prefix(std::string(prefix)), m_language(language),
  55       m_desired_type(desired_type), m_options(options) {}
  56
  57 UserExpression::~UserExpression() = default;
  58
  59 void UserExpression::InstallContext(ExecutionContext &exe_ctx) {
  60   m_jit_process_wp = exe_ctx.GetProcessSP();
  61
  62   lldb::StackFrameSP frame_sp = exe_ctx.GetFrameSP();
  63
  64   if (frame_sp)
  65     m_address = frame_sp->GetFrameCodeAddress();
  66 }
  67
  68 bool UserExpression::LockAndCheckContext(ExecutionContext &exe_ctx,
  69                                          lldb::TargetSP &target_sp,
  70                                          lldb::ProcessSP &process_sp,
  71                                          lldb::StackFrameSP &frame_sp) {
  72   lldb::ProcessSP expected_process_sp = m_jit_process_wp.lock();
  73   process_sp = exe_ctx.GetProcessSP();
  74
  75   if (process_sp != expected_process_sp)
  76     return false;
  77
  78   process_sp = exe_ctx.GetProcessSP();
  79   target_sp = exe_ctx.GetTargetSP();
  80   frame_sp = exe_ctx.GetFrameSP();
  81
  82   if (m_address.IsValid()) {
  83     if (!frame_sp)
  84       return false;
  85     return (Address::CompareLoadAddress(m_address,
  86                                         frame_sp->GetFrameCodeAddress(),
  87                                         target_sp.get()) == 0);
  88   }
  89
  90   return true;
  91 }
  92
  93 bool UserExpression::MatchesContext(ExecutionContext &exe_ctx) {
  94   lldb::TargetSP target_sp;
  95   lldb::ProcessSP process_sp;
  96   lldb::StackFrameSP frame_sp;
  97
  98   return LockAndCheckContext(exe_ctx, target_sp, process_sp, frame_sp);
  99 }
 100
 101 lldb::ValueObjectSP UserExpression::GetObjectPointerValueObject(
 102     lldb::StackFrameSP frame_sp, llvm::StringRef object_name, Status &err) {
 103   err.Clear();
 104
 105   if (!frame_sp) {
 106     err = Status::FromErrorStringWithFormatv(
 107         "Couldn't load '{0}' because the context is incomplete", object_name);
 108     return {};
 109   }
 110
 111   lldb::VariableSP var_sp;
 112   lldb::ValueObjectSP valobj_sp;
 113
 114   return frame_sp->GetValueForVariableExpressionPath(
 115       object_name, lldb::eNoDynamicValues,
 116       StackFrame::eExpressionPathOptionCheckPtrVsMember |
 117           StackFrame::eExpressionPathOptionsNoFragileObjcIvar |
 118           StackFrame::eExpressionPathOptionsNoSyntheticChildren |
 119           StackFrame::eExpressionPathOptionsNoSyntheticArrayRange,
 120       var_sp, err);
 121 }
 122
 123 lldb::addr_t UserExpression::GetObjectPointer(lldb::StackFrameSP frame_sp,
 124                                               llvm::StringRef object_name,
 125                                               Status &err) {
 126   auto valobj_sp =
 127       GetObjectPointerValueObject(std::move(frame_sp), object_name, err);
 128
 129   if (!err.Success() || !valobj_sp.get())
 130     return LLDB_INVALID_ADDRESS;
 131
 132   lldb::addr_t ret = valobj_sp->GetValueAsUnsigned(LLDB_INVALID_ADDRESS);
 133
 134   if (ret == LLDB_INVALID_ADDRESS) {
 135     err = Status::FromErrorStringWithFormatv(
 136         "Couldn't load '{0}' because its value couldn't be evaluated",
 137         object_name);
 138     return LLDB_INVALID_ADDRESS;
 139   }
 140
 141   return ret;
 142 }
 143
 144 lldb::ExpressionResults
 145 UserExpression::Evaluate(ExecutionContext &exe_ctx,
 146                          const EvaluateExpressionOptions &options,
 147                          llvm::StringRef expr, llvm::StringRef prefix,
 148                          lldb::ValueObjectSP &result_valobj_sp,
 149                          std::string *fixed_expression, ValueObject *ctx_obj) {
 150   Log *log(GetLog(LLDBLog::Expressions | LLDBLog::Step));
 151   auto set_error = [&](Status error) {
 152     result_valobj_sp = ValueObjectConstResult::Create(
 153         exe_ctx.GetBestExecutionContextScope(), std::move(error));
 154   };
 155
 156   if (ctx_obj) {
 157     static unsigned const ctx_type_mask = lldb::TypeFlags::eTypeIsClass |
 158                                           lldb::TypeFlags::eTypeIsStructUnion |
 159                                           lldb::TypeFlags::eTypeIsReference;
 160     if (!(ctx_obj->GetTypeInfo() & ctx_type_mask)) {
 161       LLDB_LOG(log, "== [UserExpression::Evaluate] Passed a context object of "
 162                     "an invalid type, can't run expressions.");
 163       set_error(Status("a context object of an invalid type passed"));
 164       return lldb::eExpressionSetupError;
 165     }
 166   }
 167
 168   if (ctx_obj && ctx_obj->GetTypeInfo() & lldb::TypeFlags::eTypeIsReference) {
 169     Status error;
 170     lldb::ValueObjectSP deref_ctx_sp = ctx_obj->Dereference(error);
 171     if (!error.Success()) {
 172       LLDB_LOG(log, "== [UserExpression::Evaluate] Passed a context object of "
 173                     "a reference type that can't be dereferenced, can't run "
 174                     "expressions.");
 175       set_error(Status(
 176           "passed context object of an reference type cannot be deferenced"));
 177       return lldb::eExpressionSetupError;
 178     }
 179
 180     ctx_obj = deref_ctx_sp.get();
 181   }
 182
 183   lldb_private::ExecutionPolicy execution_policy = options.GetExecutionPolicy();
 184   SourceLanguage language = options.GetLanguage();
 185   const ResultType desired_type = options.DoesCoerceToId()
 186                                       ? UserExpression::eResultTypeId
 187                                       : UserExpression::eResultTypeAny;
 188   Target *target = exe_ctx.GetTargetPtr();
 189   if (!target) {
 190     LLDB_LOG(log, "== [UserExpression::Evaluate] Passed a NULL target, can't "
 191                   "run expressions.");
 192     set_error(Status("expression passed a null target"));
 193     return lldb::eExpressionSetupError;
 194   }
 195
 196   Process *process = exe_ctx.GetProcessPtr();
 197
 198   if (!process && execution_policy == eExecutionPolicyAlways) {
 199     LLDB_LOG(log, "== [UserExpression::Evaluate] No process, but the policy is "
 200                   "eExecutionPolicyAlways");
 201
 202     set_error(Status("expression needed to run but couldn't: no process"));
 203
 204     return lldb::eExpressionSetupError;
 205   }
 206
 207   // Since we might need to allocate memory, we need to be stopped to run
 208   // an expression.
 209   if (process && process->GetState() != lldb::eStateStopped) {
 210     set_error(Status::FromErrorStringWithFormatv(
 211         "unable to evaluate expression while the process is {0}: the process "
 212         "must be stopped because the expression might require allocating "
 213         "memory.",
 214         StateAsCString(process->GetState())));
 215     return lldb::eExpressionSetupError;
 216   }
 217
 218   // Explicitly force the IR interpreter to evaluate the expression when the
 219   // there is no process that supports running the expression for us. Don't
 220   // change the execution policy if we have the special top-level policy that
 221   // doesn't contain any expression and there is nothing to interpret.
 222   if (execution_policy != eExecutionPolicyTopLevel &&
 223       (process == nullptr || !process->CanJIT()))
 224     execution_policy = eExecutionPolicyNever;
 225
 226   // We need to set the expression execution thread here, turns out parse can
 227   // call functions in the process of looking up symbols, which will escape the
 228   // context set by exe_ctx passed to Execute.
 229   lldb::ThreadSP thread_sp = exe_ctx.GetThreadSP();
 230   ThreadList::ExpressionExecutionThreadPusher execution_thread_pusher(
 231       thread_sp);
 232
 233   llvm::StringRef full_prefix;
 234   llvm::StringRef option_prefix(options.GetPrefix());
 235   std::string full_prefix_storage;
 236   if (!prefix.empty() && !option_prefix.empty()) {
 237     full_prefix_storage = std::string(prefix);
 238     full_prefix_storage.append(std::string(option_prefix));
 239     full_prefix = full_prefix_storage;
 240   } else if (!prefix.empty())
 241     full_prefix = prefix;
 242   else
 243     full_prefix = option_prefix;
 244
 245   // If the language was not specified in the expression command, set it to the
 246   // language in the target's properties if specified, else default to the
 247   // langage for the frame.
 248   if (!language) {
 249     if (target->GetLanguage() != lldb::eLanguageTypeUnknown)
 250       language = target->GetLanguage();
 251     else if (StackFrame *frame = exe_ctx.GetFramePtr())
 252       language = frame->GetLanguage();
 253   }
 254
 255   Status error;
 256   lldb::UserExpressionSP user_expression_sp(
 257       target->GetUserExpressionForLanguage(
 258           expr, full_prefix, language, desired_type, options, ctx_obj, error));
 259   if (error.Fail() || !user_expression_sp) {
 260     LLDB_LOG(log, "== [UserExpression::Evaluate] Getting expression: {0} ==",
 261              error.AsCString());
 262     set_error(std::move(error));
 263     return lldb::eExpressionSetupError;
 264   }
 265
 266   LLDB_LOG(log, "== [UserExpression::Evaluate] Parsing expression {0} ==",
 267            expr.str());
 268
 269   const bool keep_expression_in_memory = true;
 270   const bool generate_debug_info = options.GetGenerateDebugInfo();
 271
 272   if (options.InvokeCancelCallback(lldb::eExpressionEvaluationParse)) {
 273     set_error(Status("expression interrupted by callback before parse"));
 274     return lldb::eExpressionInterrupted;
 275   }
 276
 277   DiagnosticManager diagnostic_manager;
 278
 279   bool parse_success =
 280       user_expression_sp->Parse(diagnostic_manager, exe_ctx, execution_policy,
 281                                 keep_expression_in_memory, generate_debug_info);
 282
 283   // Calculate the fixed expression always, since we need it for errors.
 284   std::string tmp_fixed_expression;
 285   if (fixed_expression == nullptr)
 286     fixed_expression = &tmp_fixed_expression;
 287
 288   *fixed_expression = user_expression_sp->GetFixedText().str();
 289   lldb::ExpressionResults execution_results = lldb::eExpressionSetupError;
 290
 291   // If there is a fixed expression, try to parse it:
 292   if (!parse_success) {
 293     // Delete the expression that failed to parse before attempting to parse
 294     // the next expression.
 295     user_expression_sp.reset();
 296
 297     execution_results = lldb::eExpressionParseError;
 298     if (!fixed_expression->empty() && options.GetAutoApplyFixIts()) {
 299       const uint64_t max_fix_retries = options.GetRetriesWithFixIts();
 300       for (uint64_t i = 0; i < max_fix_retries; ++i) {
 301         // Try parsing the fixed expression.
 302         lldb::UserExpressionSP fixed_expression_sp(
 303             target->GetUserExpressionForLanguage(
 304                 fixed_expression->c_str(), full_prefix, language, desired_type,
 305                 options, ctx_obj, error));
 306         if (!fixed_expression_sp)
 307           break;
 308         DiagnosticManager fixed_diagnostic_manager;
 309         parse_success = fixed_expression_sp->Parse(
 310             fixed_diagnostic_manager, exe_ctx, execution_policy,
 311             keep_expression_in_memory, generate_debug_info);
 312         if (parse_success) {
 313           diagnostic_manager.Clear();
 314           user_expression_sp = fixed_expression_sp;
 315           break;
 316         }
 317         // The fixed expression also didn't parse. Let's check for any new
 318         // fixits we could try.
 319         if (!fixed_expression_sp->GetFixedText().empty()) {
 320           *fixed_expression = fixed_expression_sp->GetFixedText().str();
 321         } else {
 322           // Fixed expression didn't compile without a fixit, don't retry and
 323           // don't tell the user about it.
 324           fixed_expression->clear();
 325           break;
 326         }
 327       }
 328     }
 329
 330     if (!parse_success) {
 331       if (target->GetEnableNotifyAboutFixIts() && fixed_expression &&
 332           !fixed_expression->empty()) {
 333         std::string fixit =
 334             "fixed expression suggested:\n  " + *fixed_expression;
 335         diagnostic_manager.AddDiagnostic(fixit, lldb::eSeverityInfo,
 336                                          eDiagnosticOriginLLDB);
 337       }
 338       if (diagnostic_manager.Diagnostics().empty())
 339         error = Status::FromError(llvm::make_error<ExpressionError>(
 340             execution_results,
 341             "expression failed to parse (no further compiler diagnostics)"));
 342       else
 343         error =
 344             Status::FromError(diagnostic_manager.GetAsError(execution_results));
 345     }
 346   }
 347
 348   if (parse_success) {
 349     lldb::ExpressionVariableSP expr_result;
 350
 351     if (execution_policy == eExecutionPolicyNever &&
 352         !user_expression_sp->CanInterpret()) {
 353       LLDB_LOG(log, "== [UserExpression::Evaluate] Expression may not run, but "
 354                     "is not constant ==");
 355
 356       if (diagnostic_manager.Diagnostics().empty())
 357         error = Status::FromError(llvm::make_error<ExpressionError>(
 358             lldb::eExpressionSetupError,
 359             "expression needed to run but couldn't"));
 360     } else if (execution_policy == eExecutionPolicyTopLevel) {
 361       set_error(Status(UserExpression::kNoResult, lldb::eErrorTypeGeneric));
 362       return lldb::eExpressionCompleted;
 363     } else {
 364       if (options.InvokeCancelCallback(lldb::eExpressionEvaluationExecution)) {
 365         set_error(Status::FromError(llvm::make_error<ExpressionError>(
 366             lldb::eExpressionInterrupted,
 367             "expression interrupted by callback before execution")));
 368         return lldb::eExpressionInterrupted;
 369       }
 370
 371       diagnostic_manager.Clear();
 372
 373       LLDB_LOG(log, "== [UserExpression::Evaluate] Executing expression ==");
 374
 375       execution_results =
 376           user_expression_sp->Execute(diagnostic_manager, exe_ctx, options,
 377                                       user_expression_sp, expr_result);
 378
 379       if (execution_results != lldb::eExpressionCompleted) {
 380         LLDB_LOG(log, "== [UserExpression::Evaluate] Execution completed "
 381                       "abnormally ==");
 382
 383         if (diagnostic_manager.Diagnostics().empty())
 384           error = Status::FromError(llvm::make_error<ExpressionError>(
 385               execution_results,
 386               "expression failed to execute, unknown error"));
 387         else
 388           error = Status::FromError(
 389               diagnostic_manager.GetAsError(execution_results));
 390       } else {
 391         if (expr_result) {
 392           result_valobj_sp = expr_result->GetValueObject();
 393           result_valobj_sp->SetPreferredDisplayLanguage(
 394               language.AsLanguageType());
 395
 396           LLDB_LOG(log,
 397                    "== [UserExpression::Evaluate] Execution completed "
 398                    "normally with result {0} ==",
 399                    result_valobj_sp->GetValueAsCString());
 400         } else {
 401           LLDB_LOG(log, "== [UserExpression::Evaluate] Execution completed "
 402                         "normally with no result ==");
 403
 404           error = Status(UserExpression::kNoResult, lldb::eErrorTypeGeneric);
 405         }
 406       }
 407     }
 408   }
 409
 410   if (options.InvokeCancelCallback(lldb::eExpressionEvaluationComplete)) {
 411     set_error(Status::FromError(llvm::make_error<ExpressionError>(
 412         lldb::eExpressionInterrupted,
 413         "expression interrupted by callback after complete")));
 414     return lldb::eExpressionInterrupted;
 415   }
 416
 417   if (error.Fail())
 418     set_error(std::move(error));
 419   return execution_results;
 420 }
 421
 422 lldb::ExpressionResults
 423 UserExpression::Execute(DiagnosticManager &diagnostic_manager,
 424                         ExecutionContext &exe_ctx,
 425                         const EvaluateExpressionOptions &options,
 426                         lldb::UserExpressionSP &shared_ptr_to_me,
 427                         lldb::ExpressionVariableSP &result_var) {
 428   Debugger *debugger =
 429       exe_ctx.GetTargetPtr() ? &exe_ctx.GetTargetPtr()->GetDebugger() : nullptr;
 430   std::string details;
 431   if (m_options.IsForUtilityExpr())
 432     details = "LLDB utility";
 433   else if (m_expr_text.size() > 15)
 434     details = m_expr_text.substr(0, 14) + "…";
 435   else
 436     details = m_expr_text;
 437
 438   Progress progress("Running expression", details, {}, debugger);
 439
 440   lldb::ExpressionResults expr_result = DoExecute(
 441       diagnostic_manager, exe_ctx, options, shared_ptr_to_me, result_var);
 442   Target *target = exe_ctx.GetTargetPtr();
 443   if (options.GetSuppressPersistentResult() && result_var && target) {
 444     if (auto *persistent_state =
 445             target->GetPersistentExpressionStateForLanguage(
 446                 m_language.AsLanguageType()))
 447       persistent_state->RemovePersistentVariable(result_var);
 448   }
 449   return expr_result;
 450 }