text: //===-- ClangFunctionCaller.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 "ClangFunctionCaller.h"
  
  #include "ASTStructExtractor.h"
  #include "ClangExpressionParser.h"
  
  #include "clang/AST/ASTContext.h"
  #include "clang/AST/RecordLayout.h"
  #include "clang/CodeGen/CodeGenAction.h"
  #include "clang/CodeGen/ModuleBuilder.h"
  #include "clang/Frontend/CompilerInstance.h"
  #include "llvm/ADT/StringRef.h"
  #include "llvm/ADT/Triple.h"
  #include "llvm/ExecutionEngine/ExecutionEngine.h"
  #include "llvm/IR/Module.h"
  
  #include "lldb/Core/Module.h"
  #include "lldb/Core/ValueObject.h"
  #include "lldb/Core/ValueObjectList.h"
  #include "lldb/Expression/IRExecutionUnit.h"
  #include "lldb/Interpreter/CommandReturnObject.h"
  #include "lldb/Symbol/TypeSystemClang.h"
  #include "lldb/Symbol/Function.h"
  #include "lldb/Symbol/Type.h"
  #include "lldb/Target/ExecutionContext.h"
  #include "lldb/Target/Process.h"
  #include "lldb/Target/RegisterContext.h"
  #include "lldb/Target/Target.h"
  #include "lldb/Target/Thread.h"
  #include "lldb/Target/ThreadPlan.h"
  #include "lldb/Target/ThreadPlanCallFunction.h"
  #include "lldb/Utility/DataExtractor.h"
  #include "lldb/Utility/Log.h"
  #include "lldb/Utility/State.h"
  
  using namespace lldb_private;
  
  char ClangFunctionCaller::ID;
  
  // ClangFunctionCaller constructor
  ClangFunctionCaller::ClangFunctionCaller(ExecutionContextScope &exe_scope,
                                           const CompilerType &return_type,
                                           const Address &functionAddress,
                                           const ValueList &arg_value_list,
                                           const char *name)
      : FunctionCaller(exe_scope, return_type, functionAddress, arg_value_list,
                       name),
        m_type_system_helper(*this) {
    m_jit_process_wp = lldb::ProcessWP(exe_scope.CalculateProcess());
    // Can't make a ClangFunctionCaller without a process.
    assert(m_jit_process_wp.lock());
  }
  
  // Destructor
  ClangFunctionCaller::~ClangFunctionCaller() {}
  
  unsigned
  
  ClangFunctionCaller::CompileFunction(lldb::ThreadSP thread_to_use_sp,
                                       DiagnosticManager &diagnostic_manager) {
    if (m_compiled)
      return 0;
  
    // Compilation might call code, make sure to keep on the thread the caller
    // indicated.
    ThreadList::ExpressionExecutionThreadPusher execution_thread_pusher(
        thread_to_use_sp);
  
    // FIXME: How does clang tell us there's no return value?  We need to handle
    // that case.
    unsigned num_errors = 0;
  
    std::string return_type_str(
        m_function_return_type.GetTypeName().AsCString(""));
  
    // Cons up the function we're going to wrap our call in, then compile it...
    // We declare the function "extern "C"" because the compiler might be in C++
    // mode which would mangle the name and then we couldn't find it again...
    m_wrapper_function_text.clear();
    m_wrapper_function_text.append("extern \"C\" void ");
    m_wrapper_function_text.append(m_wrapper_function_name);
    m_wrapper_function_text.append(" (void *input)\n{\n    struct ");
    m_wrapper_function_text.append(m_wrapper_struct_name);
    m_wrapper_function_text.append(" \n  {\n");
    m_wrapper_function_text.append("    ");
    m_wrapper_function_text.append(return_type_str);
    m_wrapper_function_text.append(" (*fn_ptr) (");
  
    // Get the number of arguments.  If we have a function type and it is
    // prototyped, trust that, otherwise use the values we were given.
  
    // FIXME: This will need to be extended to handle Variadic functions.  We'll
    // need
    // to pull the defined arguments out of the function, then add the types from
    // the arguments list for the variable arguments.
  
    uint32_t num_args = UINT32_MAX;
    bool trust_function = false;
    // GetArgumentCount returns -1 for an unprototyped function.
    CompilerType function_clang_type;
    if (m_function_ptr) {
      function_clang_type = m_function_ptr->GetCompilerType();
      if (function_clang_type) {
        int num_func_args = function_clang_type.GetFunctionArgumentCount();
        if (num_func_args >= 0) {
          trust_function = true;
          num_args = num_func_args;
        }
      }
    }
  
    if (num_args == UINT32_MAX)
      num_args = m_arg_values.GetSize();
  
    std::string args_buffer; // This one stores the definition of all the args in
                             // "struct caller".
    std::string args_list_buffer; // This one stores the argument list called from
                                  // the structure.
    for (size_t i = 0; i < num_args; i++) {
      std::string type_name;
  
      if (trust_function) {
        type_name = function_clang_type.GetFunctionArgumentTypeAtIndex(i)
                        .GetTypeName()
                        .AsCString("");
      } else {
        CompilerType clang_qual_type =
            m_arg_values.GetValueAtIndex(i)->GetCompilerType();
        if (clang_qual_type) {
          type_name = clang_qual_type.GetTypeName().AsCString("");
        } else {
          diagnostic_manager.Printf(
              eDiagnosticSeverityError,
              "Could not determine type of input value %" PRIu64 ".",
              (uint64_t)i);
          return 1;
        }
      }
  
      m_wrapper_function_text.append(type_name);
      if (i < num_args - 1)
        m_wrapper_function_text.append(", ");
  
      char arg_buf[32];
      args_buffer.append("    ");
      args_buffer.append(type_name);
      snprintf(arg_buf, 31, "arg_%" PRIu64, (uint64_t)i);
      args_buffer.push_back(' ');
      args_buffer.append(arg_buf);
      args_buffer.append(";\n");
  
      args_list_buffer.append("__lldb_fn_data->");
      args_list_buffer.append(arg_buf);
      if (i < num_args - 1)
        args_list_buffer.append(", ");
    }
    m_wrapper_function_text.append(
        ");\n"); // Close off the function calling prototype.
  
    m_wrapper_function_text.append(args_buffer);
  
    m_wrapper_function_text.append("    ");
    m_wrapper_function_text.append(return_type_str);
    m_wrapper_function_text.append(" return_value;");
    m_wrapper_function_text.append("\n  };\n  struct ");
    m_wrapper_function_text.append(m_wrapper_struct_name);
    m_wrapper_function_text.append("* __lldb_fn_data = (struct ");
    m_wrapper_function_text.append(m_wrapper_struct_name);
    m_wrapper_function_text.append(" *) input;\n");
  
    m_wrapper_function_text.append(
        "  __lldb_fn_data->return_value = __lldb_fn_data->fn_ptr (");
    m_wrapper_function_text.append(args_list_buffer);
    m_wrapper_function_text.append(");\n}\n");
  
    Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_EXPRESSIONS));
    LLDB_LOGF(log, "Expression: \n\n%s\n\n", m_wrapper_function_text.c_str());
  
    // Okay, now compile this expression
  
    lldb::ProcessSP jit_process_sp(m_jit_process_wp.lock());
    if (jit_process_sp) {
      const bool generate_debug_info = true;
      auto *clang_parser = new ClangExpressionParser(jit_process_sp.get(), *this,
                                                     generate_debug_info);
      num_errors = clang_parser->Parse(diagnostic_manager);
      m_parser.reset(clang_parser);
    } else {
      diagnostic_manager.PutString(eDiagnosticSeverityError,
                                   "no process - unable to inject function");
      num_errors = 1;
    }
  
    m_compiled = (num_errors == 0);
  
    if (!m_compiled)
      return num_errors;
  
    return num_errors;
  }
  
  clang::ASTConsumer *
  ClangFunctionCaller::ClangFunctionCallerHelper::ASTTransformer(
      clang::ASTConsumer *passthrough) {
    m_struct_extractor.reset(new ASTStructExtractor(
        passthrough, m_owner.GetWrapperStructName(), m_owner));
  
    return m_struct_extractor.get();
  }
  