text: //===-- LLVMUserExpression.cpp --------------------------------------------===//
  //
  // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
  // See https://llvm.org/LICENSE.txt for license information.
  // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
  //
  //===----------------------------------------------------------------------===//
  
  
  #include "lldb/Expression/LLVMUserExpression.h"
  #include "lldb/Core/Module.h"
  #include "lldb/Core/StreamFile.h"
  #include "lldb/Core/ValueObjectConstResult.h"
  #include "lldb/Expression/DiagnosticManager.h"
  #include "lldb/Expression/ExpressionVariable.h"
  #include "lldb/Expression/IRExecutionUnit.h"
  #include "lldb/Expression/IRInterpreter.h"
  #include "lldb/Expression/Materializer.h"
  #include "lldb/Host/HostInfo.h"
  #include "lldb/Symbol/Block.h"
  #include "lldb/Symbol/Function.h"
  #include "lldb/Symbol/ObjectFile.h"
  #include "lldb/Symbol/SymbolVendor.h"
  #include "lldb/Symbol/Type.h"
  #include "lldb/Symbol/VariableList.h"
  #include "lldb/Target/ExecutionContext.h"
  #include "lldb/Target/Process.h"
  #include "lldb/Target/StackFrame.h"
  #include "lldb/Target/Target.h"
  #include "lldb/Target/ThreadPlan.h"
  #include "lldb/Target/ThreadPlanCallUserExpression.h"
  #include "lldb/Utility/ConstString.h"
  #include "lldb/Utility/Log.h"
  #include "lldb/Utility/StreamString.h"
  
  using namespace lldb_private;
  
  char LLVMUserExpression::ID;
  
  LLVMUserExpression::LLVMUserExpression(ExecutionContextScope &exe_scope,
                                         llvm::StringRef expr,
                                         llvm::StringRef prefix,
                                         lldb::LanguageType language,
                                         ResultType desired_type,
                                         const EvaluateExpressionOptions &options)
      : UserExpression(exe_scope, expr, prefix, language, desired_type, options),
        m_stack_frame_bottom(LLDB_INVALID_ADDRESS),
        m_stack_frame_top(LLDB_INVALID_ADDRESS), m_allow_cxx(false),
        m_allow_objc(false), m_transformed_text(), m_execution_unit_sp(),
        m_materializer_up(), m_jit_module_wp(), m_can_interpret(false),
        m_materialized_address(LLDB_INVALID_ADDRESS) {}
  
  LLVMUserExpression::~LLVMUserExpression() {
    if (m_target) {
      lldb::ModuleSP jit_module_sp(m_jit_module_wp.lock());
      if (jit_module_sp)
        m_target->GetImages().Remove(jit_module_sp);
    }
  }
  
  lldb::ExpressionResults
  LLVMUserExpression::DoExecute(DiagnosticManager &diagnostic_manager,
                                ExecutionContext &exe_ctx,
                                const EvaluateExpressionOptions &options,
                                lldb::UserExpressionSP &shared_ptr_to_me,
                                lldb::ExpressionVariableSP &result) {
    // The expression log is quite verbose, and if you're just tracking the
    // execution of the expression, it's quite convenient to have these logs come
    // out with the STEP log as well.
    Log *log(lldb_private::GetLogIfAnyCategoriesSet(LIBLLDB_LOG_EXPRESSIONS |
                                                    LIBLLDB_LOG_STEP));
  
    if (m_jit_start_addr == LLDB_INVALID_ADDRESS && !m_can_interpret) {
      diagnostic_manager.PutString(
          eDiagnosticSeverityError,
          "Expression can't be run, because there is no JIT compiled function");
      return lldb::eExpressionSetupError;
    }
  
    lldb::addr_t struct_address = LLDB_INVALID_ADDRESS;
  
    if (!PrepareToExecuteJITExpression(diagnostic_manager, exe_ctx,
                                       struct_address)) {
      diagnostic_manager.Printf(
          eDiagnosticSeverityError,
          "errored out in %s, couldn't PrepareToExecuteJITExpression",
          __FUNCTION__);
      return lldb::eExpressionSetupError;
    }
  
    lldb::addr_t function_stack_bottom = LLDB_INVALID_ADDRESS;
    lldb::addr_t function_stack_top = LLDB_INVALID_ADDRESS;
  
    lldb::ValueObjectSP error_backstop_result_sp;
  
    if (m_can_interpret) {
      llvm::Module *module = m_execution_unit_sp->GetModule();
      llvm::Function *function = m_execution_unit_sp->GetFunction();
  
      if (!module || !function) {
        diagnostic_manager.PutString(
            eDiagnosticSeverityError,
            "supposed to interpret, but nothing is there");
        return lldb::eExpressionSetupError;
      }
  
      Status interpreter_error;
  
      std::vector<lldb::addr_t> args;
  
      if (!AddArguments(exe_ctx, args, struct_address, diagnostic_manager)) {
        diagnostic_manager.Printf(eDiagnosticSeverityError,
                                  "errored out in %s, couldn't AddArguments",
                                  __FUNCTION__);
        return lldb::eExpressionSetupError;
      }
  
      function_stack_bottom = m_stack_frame_bottom;
      function_stack_top = m_stack_frame_top;
  
      IRInterpreter::Interpret(*module, *function, args, *m_execution_unit_sp,
                               interpreter_error, function_stack_bottom,
                               function_stack_top, exe_ctx);
  
      if (!interpreter_error.Success()) {
        diagnostic_manager.Printf(eDiagnosticSeverityError,
                                  "supposed to interpret, but failed: %s",
                                  interpreter_error.AsCString());
        return lldb::eExpressionDiscarded;
      }
    } else {
      if (!exe_ctx.HasThreadScope()) {
        diagnostic_manager.Printf(eDiagnosticSeverityError,
                                  "%s called with no thread selected",
                                  __FUNCTION__);
        return lldb::eExpressionSetupError;
      }
  
      // Store away the thread ID for error reporting, in case it exits
      // during execution:
      lldb::tid_t expr_thread_id = exe_ctx.GetThreadRef().GetID();
  
      Address wrapper_address(m_jit_start_addr);
  
      std::vector<lldb::addr_t> args;
  
      if (!AddArguments(exe_ctx, args, struct_address, diagnostic_manager)) {
        diagnostic_manager.Printf(eDiagnosticSeverityError,
                                  "errored out in %s, couldn't AddArguments",
                                  __FUNCTION__);
        return lldb::eExpressionSetupError;
      }
  
      lldb::ThreadPlanSP call_plan_sp(new ThreadPlanCallUserExpression(
          exe_ctx.GetThreadRef(), wrapper_address, args, options,
          shared_ptr_to_me));
  
      StreamString ss;
      if (!call_plan_sp || !call_plan_sp->ValidatePlan(&ss)) {
        diagnostic_manager.PutString(eDiagnosticSeverityError, ss.GetString());
        return lldb::eExpressionSetupError;
      }
  
      ThreadPlanCallUserExpression *user_expression_plan =
          static_cast<ThreadPlanCallUserExpression *>(call_plan_sp.get());
  
      lldb::addr_t function_stack_pointer =
          user_expression_plan->GetFunctionStackPointer();
  
      function_stack_bottom = function_stack_pointer - HostInfo::GetPageSize();
      function_stack_top = function_stack_pointer;
  
      LLDB_LOGF(log,
                "-- [UserExpression::Execute] Execution of expression begins --");
  
      if (exe_ctx.GetProcessPtr())
        exe_ctx.GetProcessPtr()->SetRunningUserExpression(true);
  
      lldb::ExpressionResults execution_result =
          exe_ctx.GetProcessRef().RunThreadPlan(exe_ctx, call_plan_sp, options,
                                                diagnostic_manager);
  
      if (exe_ctx.GetProcessPtr())
        exe_ctx.GetProcessPtr()->SetRunningUserExpression(false);
  
      LLDB_LOGF(log, "-- [UserExpression::Execute] Execution of expression "
                     "completed --");
  
      if (execution_result == lldb::eExpressionInterrupted ||
          execution_result == lldb::eExpressionHitBreakpoint) {
        const char *error_desc = nullptr;
  
        if (user_expression_plan) {
          if (auto real_stop_info_sp = user_expression_plan->GetRealStopInfo())
            error_desc = real_stop_info_sp->GetDescription();
        }
        if (error_desc)
          diagnostic_manager.Printf(eDiagnosticSeverityError,
                                    "Execution was interrupted, reason: %s.",
                                    error_desc);
        else
          diagnostic_manager.PutString(eDiagnosticSeverityError,
                                       "Execution was interrupted.");
  
        if ((execution_result == lldb::eExpressionInterrupted &&
             options.DoesUnwindOnError()) ||
            (execution_result == lldb::eExpressionHitBreakpoint &&
             options.DoesIgnoreBreakpoints()))
          diagnostic_manager.AppendMessageToDiagnostic(
              "The process has been returned to the state before expression "
              "evaluation.");
        else {
          if (execution_result == lldb::eExpressionHitBreakpoint)
            user_expression_plan->TransferExpressionOwnership();
          diagnostic_manager.AppendMessageToDiagnostic(
              "The process has been left at the point where it was "
              "interrupted, "
              "use \"thread return -x\" to return to the state before "
              "expression evaluation.");
        }
  
        return execution_result;
      } else if (execution_result == lldb::eExpressionStoppedForDebug) {
        diagnostic_manager.PutString(
            eDiagnosticSeverityRemark,
            "Execution was halted at the first instruction of the expression "
            "function because \"debug\" was requested.\n"
            "Use \"thread return -x\" to return to the state before expression "
            "evaluation.");
        return execution_result;
      } else if (execution_result == lldb::eExpressionCompleted) {
        if (user_expression_plan->HitErrorBackstop()) {
          // This should only happen in Playground & REPL.  The code threw an
          // uncaught error, so we already rolled up
          // the stack past our execution point.  We're not going to be able to
          // get any or our expression variables
          // since they've already gone out of scope.  But at least we can
          // gather the error result...
          if (user_expression_plan->GetReturnValueObject() &&
              user_expression_plan->GetReturnValueObject()
                  ->GetError()
                  .Success()) {
            error_backstop_result_sp =
                user_expression_plan->GetReturnValueObject();
          }
        }
      } else if (execution_result == lldb::eExpressionThreadVanished) {
        diagnostic_manager.Printf(
            eDiagnosticSeverityError,
            "Couldn't complete execution; the thread "
            "on which the expression was being run: 0x%" PRIx64
            " exited during its execution.", 
            expr_thread_id);
        return execution_result;
      } else {
        diagnostic_manager.Printf(
            eDiagnosticSeverityError, "Couldn't execute function; result was %s",
            Process::ExecutionResultAsCString(execution_result));
        return execution_result;
      }
    }
  
    if (error_backstop_result_sp) {
      // This should only happen in Playground & REPL.  The code threw an
      // uncaught error, so we already rolled up
      // the stack past our execution point.  We're not going to be able to get
      // any or our expression variables
      // since they've already gone out of scope.  But at least we can gather
      // the error result...
      Target *target = exe_ctx.GetTargetPtr();
      PersistentExpressionState *expression_state =
          target->GetPersistentExpressionStateForLanguage(Language());
      if (expression_state)
        result = expression_state->CreatePersistentVariable(
            error_backstop_result_sp);
  
      return lldb::eExpressionCompleted;
    } else if (FinalizeJITExecution(diagnostic_manager, exe_ctx, result,
                                    function_stack_bottom,
                                    function_stack_top)) {
      return lldb::eExpressionCompleted;
    } else {
      return lldb::eExpressionResultUnavailable;
    }
  }
  
  bool LLVMUserExpression::FinalizeJITExecution(
      DiagnosticManager &diagnostic_manager, ExecutionContext &exe_ctx,
      lldb::ExpressionVariableSP &result, lldb::addr_t function_stack_bottom,
      lldb::addr_t function_stack_top) {
    Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_EXPRESSIONS));
  
    LLDB_LOGF(log, "-- [UserExpression::FinalizeJITExecution] Dematerializing "
                   "after execution --");
  
    if (!m_dematerializer_sp) {
      diagnostic_manager.Printf(eDiagnosticSeverityError,
                                "Couldn't apply expression side effects : no "
                                "dematerializer is present");
      return false;
    }
  
    Status dematerialize_error;
  
    m_dematerializer_sp->Dematerialize(dematerialize_error, function_stack_bottom,
                                       function_stack_top);
  
    if (!dematerialize_error.Success()) {
      diagnostic_manager.Printf(eDiagnosticSeverityError,
                                "Couldn't apply expression side effects : %s",
                                dematerialize_error.AsCString("unknown error"));
      return false;
    }
  
    result =
        GetResultAfterDematerialization(exe_ctx.GetBestExecutionContextScope());
  
    if (result)
      result->TransferAddress();
  
    m_dematerializer_sp.reset();
  
    return true;
  }
  
  bool LLVMUserExpression::PrepareToExecuteJITExpression(
      DiagnosticManager &diagnostic_manager, ExecutionContext &exe_ctx,
      lldb::addr_t &struct_address) {
    lldb::TargetSP target;
    lldb::ProcessSP process;
    lldb::StackFrameSP frame;
  
    if (!LockAndCheckContext(exe_ctx, target, process, frame)) {
      diagnostic_manager.PutString(
          eDiagnosticSeverityError,
          "The context has changed before we could JIT the expression!");
      return false;
    }
  
    if (m_options.GetREPLEnabled()) {
      Status materialize_error;
  
      m_dematerializer_sp = m_materializer_up->Materialize(
          frame, *m_execution_unit_sp, LLDB_INVALID_ADDRESS, materialize_error);
  
      if (!materialize_error.Success()) {
        diagnostic_manager.Printf(eDiagnosticSeverityError,
                                  "Couldn't materialize: %s\n",
                                  materialize_error.AsCString());
        return false;
      }
  
      return true;
    }
  
    if (m_jit_start_addr != LLDB_INVALID_ADDRESS || m_can_interpret) {
      if (m_materialized_address == LLDB_INVALID_ADDRESS) {
        Status alloc_error;
  
        IRMemoryMap::AllocationPolicy policy =
            m_can_interpret ? IRMemoryMap::eAllocationPolicyHostOnly
                            : IRMemoryMap::eAllocationPolicyMirror;
  
        const bool zero_memory = false;
  
        m_materialized_address = m_execution_unit_sp->Malloc(
            m_materializer_up->GetStructByteSize(),
            m_materializer_up->GetStructAlignment(),
            lldb::ePermissionsReadable | lldb::ePermissionsWritable, policy,
            zero_memory, alloc_error);
  
        if (!alloc_error.Success()) {
          diagnostic_manager.Printf(
              eDiagnosticSeverityError,
              "Couldn't allocate space for materialized struct: %s",
              alloc_error.AsCString());
          return false;
        }
      }
  
      struct_address = m_materialized_address;
  
      if (m_can_interpret && m_stack_frame_bottom == LLDB_INVALID_ADDRESS) {
        Status alloc_error;
  
        const size_t stack_frame_size = 512 * 1024;
  
        const bool zero_memory = false;
  
        m_stack_frame_bottom = m_execution_unit_sp->Malloc(
            stack_frame_size, 8,
            lldb::ePermissionsReadable | lldb::ePermissionsWritable,
            IRMemoryMap::eAllocationPolicyHostOnly, zero_memory, alloc_error);
  
        m_stack_frame_top = m_stack_frame_bottom + stack_frame_size;
  
        if (!alloc_error.Success()) {
          diagnostic_manager.Printf(
              eDiagnosticSeverityError,
              "Couldn't allocate space for the stack frame: %s",
              alloc_error.AsCString());
          return false;
        }
      }
  
      Status materialize_error;
  
      m_dematerializer_sp = m_materializer_up->Materialize(
          frame, *m_execution_unit_sp, struct_address, materialize_error);
  
      if (!materialize_error.Success()) {
        diagnostic_manager.Printf(eDiagnosticSeverityError,
                                  "Couldn't materialize: %s",
                                  materialize_error.AsCString());
        return false;
      }
    }
    return true;
  }
  
  