lldb/source/Plugins/ExpressionParser/Clang/ClangUserExpression.cpp

//===-- ClangUserExpression.cpp ---------------------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#include <stdio.h>
#if HAVE_SYS_TYPES_H
#  include <sys/types.h>
#endif

#include <cstdlib>
#include <string>
#include <map>

#include "ClangUserExpression.h"

#include "ASTResultSynthesizer.h"
#include "ClangExpressionDeclMap.h"
#include "ClangExpressionParser.h"
#include "ClangModulesDeclVendor.h"
#include "ClangPersistentVariables.h"
#include "ClangDiagnostic.h"

#include "lldb/Core/ConstString.h"
#include "lldb/Core/Log.h"
#include "lldb/Core/Module.h"
#include "lldb/Core/StreamFile.h"
#include "lldb/Core/StreamString.h"
#include "lldb/Core/ValueObjectConstResult.h"
#include "lldb/Expression/ExpressionSourceCode.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/ClangASTContext.h"
#include "lldb/Symbol/Function.h"
#include "lldb/Symbol/ObjectFile.h"
#include "lldb/Symbol/SymbolVendor.h"
#include "lldb/Symbol/Type.h"
#include "lldb/Symbol/ClangExternalASTSourceCommon.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 "clang/AST/DeclCXX.h"
#include "clang/AST/DeclObjC.h"

using namespace lldb_private;

ClangUserExpression::ClangUserExpression(ExecutionContextScope &exe_scope, const char *expr, const char *expr_prefix,
                                         lldb::LanguageType language, ResultType desired_type,
                                         const EvaluateExpressionOptions &options)
    : LLVMUserExpression(exe_scope, expr, expr_prefix, language, desired_type, options),
      m_type_system_helper(*m_target_wp.lock().get(), options.GetExecutionPolicy() == eExecutionPolicyTopLevel)
{
    switch (m_language)
    {
        case lldb::eLanguageTypeC_plus_plus:
            m_allow_cxx = true;
            break;
        case lldb::eLanguageTypeObjC:
            m_allow_objc = true;
            break;
        case lldb::eLanguageTypeObjC_plus_plus:
        default:
            m_allow_cxx = true;
            m_allow_objc = true;
            break;
    }
}

ClangUserExpression::~ClangUserExpression ()
{
}

void
ClangUserExpression::ScanContext(ExecutionContext &exe_ctx, Error &err)
{
    Log *log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_EXPRESSIONS));

    if (log)
        log->Printf("ClangUserExpression::ScanContext()");

    m_target = exe_ctx.GetTargetPtr();

    if (!(m_allow_cxx || m_allow_objc))
    {
        if (log)
            log->Printf("  [CUE::SC] Settings inhibit C++ and Objective-C");
        return;
    }

    StackFrame *frame = exe_ctx.GetFramePtr();
    if (frame == NULL)
    {
        if (log)
            log->Printf("  [CUE::SC] Null stack frame");
        return;
    }

    SymbolContext sym_ctx = frame->GetSymbolContext(lldb::eSymbolContextFunction | lldb::eSymbolContextBlock);

    if (!sym_ctx.function)
    {
        if (log)
            log->Printf("  [CUE::SC] Null function");
        return;
    }

    // Find the block that defines the function represented by "sym_ctx"
    Block *function_block = sym_ctx.GetFunctionBlock();

    if (!function_block)
    {
        if (log)
            log->Printf("  [CUE::SC] Null function block");
        return;
    }

    CompilerDeclContext decl_context = function_block->GetDeclContext();

    if (!decl_context)
    {
        if (log)
            log->Printf("  [CUE::SC] Null decl context");
        return;
    }

    if (clang::CXXMethodDecl *method_decl = ClangASTContext::DeclContextGetAsCXXMethodDecl(decl_context))
    {
        if (m_allow_cxx && method_decl->isInstance())
        {
            if (m_enforce_valid_object)
            {
                lldb::VariableListSP variable_list_sp (function_block->GetBlockVariableList (true));

                const char *thisErrorString = "Stopped in a C++ method, but 'this' isn't available; pretending we are in a generic context";

                if (!variable_list_sp)
                {
                    err.SetErrorString(thisErrorString);
                    return;
                }

                lldb::VariableSP this_var_sp (variable_list_sp->FindVariable(ConstString("this")));

                if (!this_var_sp ||
                    !this_var_sp->IsInScope(frame) ||
                    !this_var_sp->LocationIsValidForFrame (frame))
                {
                    err.SetErrorString(thisErrorString);
                    return;
                }
            }

            m_in_cplusplus_method = true;
            m_needs_object_ptr = true;
        }
    }
    else if (clang::ObjCMethodDecl *method_decl = ClangASTContext::DeclContextGetAsObjCMethodDecl(decl_context))
    {
        if (m_allow_objc)
        {
            if (m_enforce_valid_object)
            {
                lldb::VariableListSP variable_list_sp (function_block->GetBlockVariableList (true));

                const char *selfErrorString = "Stopped in an Objective-C method, but 'self' isn't available; pretending we are in a generic context";

                if (!variable_list_sp)
                {
                    err.SetErrorString(selfErrorString);
                    return;
                }

                lldb::VariableSP self_variable_sp = variable_list_sp->FindVariable(ConstString("self"));

                if (!self_variable_sp ||
                    !self_variable_sp->IsInScope(frame) ||
                    !self_variable_sp->LocationIsValidForFrame (frame))
                {
                    err.SetErrorString(selfErrorString);
                    return;
                }
            }

            m_in_objectivec_method = true;
            m_needs_object_ptr = true;

            if (!method_decl->isInstanceMethod())
                m_in_static_method = true;
        }
    }
    else if (clang::FunctionDecl *function_decl = ClangASTContext::DeclContextGetAsFunctionDecl(decl_context))
    {
        // We might also have a function that said in the debug information that it captured an
        // object pointer.  The best way to deal with getting to the ivars at present is by pretending
        // that this is a method of a class in whatever runtime the debug info says the object pointer
        // belongs to.  Do that here.

        ClangASTMetadata *metadata = ClangASTContext::DeclContextGetMetaData (decl_context, function_decl);
        if (metadata && metadata->HasObjectPtr())
        {
            lldb::LanguageType language = metadata->GetObjectPtrLanguage();
            if (language == lldb::eLanguageTypeC_plus_plus)
            {
                if (m_enforce_valid_object)
                {
                    lldb::VariableListSP variable_list_sp (function_block->GetBlockVariableList (true));

                    const char *thisErrorString = "Stopped in a context claiming to capture a C++ object pointer, but 'this' isn't available; pretending we are in a generic context";

                    if (!variable_list_sp)
                    {
                        err.SetErrorString(thisErrorString);
                        return;
                    }

                    lldb::VariableSP this_var_sp (variable_list_sp->FindVariable(ConstString("this")));

                    if (!this_var_sp ||
                        !this_var_sp->IsInScope(frame) ||
                        !this_var_sp->LocationIsValidForFrame (frame))
                    {
                        err.SetErrorString(thisErrorString);
                        return;
                    }
                }

                m_in_cplusplus_method = true;
                m_needs_object_ptr = true;
            }
            else if (language == lldb::eLanguageTypeObjC)
            {
                if (m_enforce_valid_object)
                {
                    lldb::VariableListSP variable_list_sp (function_block->GetBlockVariableList (true));

                    const char *selfErrorString = "Stopped in a context claiming to capture an Objective-C object pointer, but 'self' isn't available; pretending we are in a generic context";

                    if (!variable_list_sp)
                    {
                        err.SetErrorString(selfErrorString);
                        return;
                    }

                    lldb::VariableSP self_variable_sp = variable_list_sp->FindVariable(ConstString("self"));

                    if (!self_variable_sp ||
                        !self_variable_sp->IsInScope(frame) ||
                        !self_variable_sp->LocationIsValidForFrame (frame))
                    {
                        err.SetErrorString(selfErrorString);
                        return;
                    }

                    Type *self_type = self_variable_sp->GetType();

                    if (!self_type)
                    {
                        err.SetErrorString(selfErrorString);
                        return;
                    }

                    CompilerType self_clang_type = self_type->GetForwardCompilerType ();

                    if (!self_clang_type)
                    {
                        err.SetErrorString(selfErrorString);
                        return;
                    }

                    if (ClangASTContext::IsObjCClassType(self_clang_type))
                    {
                        return;
                    }
                    else if (ClangASTContext::IsObjCObjectPointerType(self_clang_type))
                    {
                        m_in_objectivec_method = true;
                        m_needs_object_ptr = true;
                    }
                    else
                    {
                        err.SetErrorString(selfErrorString);
                        return;
                    }
                }
                else
                {
                    m_in_objectivec_method = true;
                    m_needs_object_ptr = true;
                }
            }
        }
    }
}

// This is a really nasty hack, meant to fix Objective-C expressions of the form
// (int)[myArray count].  Right now, because the type information for count is
// not available, [myArray count] returns id, which can't be directly cast to
// int without causing a clang error.
static void
ApplyObjcCastHack(std::string &expr)
{
#define OBJC_CAST_HACK_FROM "(int)["
#define OBJC_CAST_HACK_TO   "(int)(long long)["

    size_t from_offset;

    while ((from_offset = expr.find(OBJC_CAST_HACK_FROM)) != expr.npos)
        expr.replace(from_offset, sizeof(OBJC_CAST_HACK_FROM) - 1, OBJC_CAST_HACK_TO);

#undef OBJC_CAST_HACK_TO
#undef OBJC_CAST_HACK_FROM
}

bool
ClangUserExpression::Parse(DiagnosticManager &diagnostic_manager, ExecutionContext &exe_ctx,
                           lldb_private::ExecutionPolicy execution_policy, bool keep_result_in_memory,
                           bool generate_debug_info)
{
    Log *log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_EXPRESSIONS));

    Error err;

    InstallContext(exe_ctx);
    
    if (Target *target = exe_ctx.GetTargetPtr())
    {
        if (PersistentExpressionState *persistent_state = target->GetPersistentExpressionStateForLanguage(lldb::eLanguageTypeC))
        {
            m_result_delegate.RegisterPersistentState(persistent_state);
        }
        else
        {
            diagnostic_manager.PutCString(eDiagnosticSeverityError, "couldn't start parsing (no persistent data)");
            return false;
        }
    }
    else
    {
        diagnostic_manager.PutCString(eDiagnosticSeverityError, "error: couldn't start parsing (no target)");
        return false;
    }

    ScanContext(exe_ctx, err);

    if (!err.Success())
    {
        diagnostic_manager.PutCString(eDiagnosticSeverityWarning, err.AsCString());
    }

    ////////////////////////////////////
    // Generate the expression
    //

    ApplyObjcCastHack(m_expr_text);
    //ApplyUnicharHack(m_expr_text);

    std::string prefix = m_expr_prefix;
    
    if (ClangModulesDeclVendor *decl_vendor = m_target->GetClangModulesDeclVendor())
    {
        const ClangModulesDeclVendor::ModuleVector &hand_imported_modules = llvm::cast<ClangPersistentVariables>(m_target->GetPersistentExpressionStateForLanguage(lldb::eLanguageTypeC))->GetHandLoadedClangModules();
        ClangModulesDeclVendor::ModuleVector modules_for_macros;
        
        for (ClangModulesDeclVendor::ModuleID module : hand_imported_modules)
        {
            modules_for_macros.push_back(module);
        }

        if (m_target->GetEnableAutoImportClangModules())
        {
            if (StackFrame *frame = exe_ctx.GetFramePtr())
            {
                if (Block *block = frame->GetFrameBlock())
                {
                    SymbolContext sc;
                    
                    block->CalculateSymbolContext(&sc);
                    
                    if (sc.comp_unit)
                    {
                        StreamString error_stream;
                        
                        decl_vendor->AddModulesForCompileUnit(*sc.comp_unit, modules_for_macros, error_stream);
                    }
                }
            }
        }
    }

    if (m_options.GetExecutionPolicy() == eExecutionPolicyTopLevel)
    {
        m_transformed_text = m_expr_text;
    }
    else
    {
        std::unique_ptr<ExpressionSourceCode> source_code(
            ExpressionSourceCode::CreateWrapped(prefix.c_str(), m_expr_text.c_str()));

        lldb::LanguageType lang_type;

        if (m_in_cplusplus_method)
            lang_type = lldb::eLanguageTypeC_plus_plus;
        else if (m_in_objectivec_method)
            lang_type = lldb::eLanguageTypeObjC;
        else
            lang_type = lldb::eLanguageTypeC;

        if (!source_code->GetText(m_transformed_text, lang_type, m_const_object, m_in_static_method, exe_ctx))
        {
            diagnostic_manager.PutCString(eDiagnosticSeverityError, "couldn't construct expression body");
            return false;
        }
    }

    if (log)
        log->Printf("Parsing the following code:\n%s", m_transformed_text.c_str());

    ////////////////////////////////////
    // Set up the target and compiler
    //

    Target *target = exe_ctx.GetTargetPtr();

    if (!target)
    {
        diagnostic_manager.PutCString(eDiagnosticSeverityError, "invalid target");
        return false;
    }

    //////////////////////////
    // Parse the expression
    //

    m_materializer_ap.reset(new Materializer());

    ResetDeclMap(exe_ctx, m_result_delegate, keep_result_in_memory);

    class OnExit
    {
    public:
        typedef std::function <void (void)> Callback;

        OnExit (Callback const &callback) :
            m_callback(callback)
        {
        }

        ~OnExit ()
        {
            m_callback();
        }
    private:
        Callback m_callback;
    };

    OnExit on_exit([this]() { ResetDeclMap(); });

    if (!DeclMap()->WillParse(exe_ctx, m_materializer_ap.get()))
    {
        diagnostic_manager.PutCString(eDiagnosticSeverityError,
                                      "current process state is unsuitable for expression parsing");

        ResetDeclMap(); // We are being careful here in the case of breakpoint conditions.

        return false;
    }

    if (m_options.GetExecutionPolicy() == eExecutionPolicyTopLevel)
    {
        DeclMap()->SetLookupsEnabled(true);
    }

    Process *process = exe_ctx.GetProcessPtr();
    ExecutionContextScope *exe_scope = process;

    if (!exe_scope)
        exe_scope = exe_ctx.GetTargetPtr();

    // We use a shared pointer here so we can use the original parser - if it succeeds
    // or the rewrite parser we might make if it fails.  But the parser_sp will never be empty.
    
    std::shared_ptr<ClangExpressionParser> parser_sp(new ClangExpressionParser(exe_scope, *this, generate_debug_info));

    unsigned num_errors = parser_sp->Parse(diagnostic_manager);

    // Check here for FixItHints.  If there are any try fixing the source and re-parsing...
    if (num_errors && diagnostic_manager.HasFixIts() && diagnostic_manager.ShouldAutoApplyFixIts())
    {
        if (parser_sp->RewriteExpression(diagnostic_manager))
        {
            std::string backup_source = std::move(m_transformed_text);
            m_transformed_text = diagnostic_manager.GetFixedExpression();
            // Make a new diagnostic manager and parser, and try again with the rewritten expression:
            // FIXME: It would be nice to reuse the parser we have but that doesn't seem to be possible.
            DiagnosticManager rewrite_manager;
            std::shared_ptr<ClangExpressionParser> rewrite_parser_sp(new ClangExpressionParser(exe_scope, *this, generate_debug_info));
            unsigned rewrite_errors = rewrite_parser_sp->Parse(rewrite_manager);
            if (rewrite_errors == 0)
            {
                diagnostic_manager.Clear();
                parser_sp = rewrite_parser_sp;
                num_errors = 0;
            }
            else
            {
                m_transformed_text = std::move(backup_source);
            }
        }
    }
    
    if (num_errors)
    {
        diagnostic_manager.Printf(eDiagnosticSeverityError, "%u error%s parsing expression", num_errors,
                                  num_errors == 1 ? "" : "s");

        ResetDeclMap(); // We are being careful here in the case of breakpoint conditions.

        return false;
    }

    //////////////////////////////////////////////////////////////////////////////////////////
    // Prepare the output of the parser for execution, evaluating it statically if possible
    //

    {
        Error jit_error = parser_sp->PrepareForExecution(m_jit_start_addr,
                                                         m_jit_end_addr,
                                                         m_execution_unit_sp,
                                                         exe_ctx,
                                                         m_can_interpret,
                                                         execution_policy);

        if (!jit_error.Success())
        {
            const char *error_cstr = jit_error.AsCString();
            if (error_cstr && error_cstr[0])
                diagnostic_manager.PutCString(eDiagnosticSeverityError, error_cstr);
            else
                diagnostic_manager.PutCString(eDiagnosticSeverityError, "expression can't be interpreted or run");
            return false;
        }
    }

    if (exe_ctx.GetProcessPtr() && execution_policy == eExecutionPolicyTopLevel)
    {
        Error static_init_error = parser_sp->RunStaticInitializers(m_execution_unit_sp, exe_ctx);

        if (!static_init_error.Success())
        {
            const char *error_cstr = static_init_error.AsCString();
            if (error_cstr && error_cstr[0])
                diagnostic_manager.Printf(eDiagnosticSeverityError, "couldn't run static initializers: %s\n",
                                          error_cstr);
            else
                diagnostic_manager.PutCString(eDiagnosticSeverityError, "couldn't run static initializers\n");
            return false;
        }
    }

    if (m_execution_unit_sp)
    {
        bool register_execution_unit = false;

        if (m_options.GetExecutionPolicy() == eExecutionPolicyTopLevel)
        {
            register_execution_unit = true;
        }

        if (register_execution_unit)
        {
            // We currently key off there being more than one external function in the execution
            // unit to determine whether it needs to live in the process.

            llvm::cast<PersistentExpressionState>(
                exe_ctx.GetTargetPtr()->GetPersistentExpressionStateForLanguage(m_language))
                ->RegisterExecutionUnit(m_execution_unit_sp);
        }
    }

    if (generate_debug_info)
    {
        lldb::ModuleSP jit_module_sp(m_execution_unit_sp->GetJITModule());

        if (jit_module_sp)
        {
            ConstString const_func_name(FunctionName());
            FileSpec jit_file;
            jit_file.GetFilename() = const_func_name;
            jit_module_sp->SetFileSpecAndObjectName (jit_file, ConstString());
            m_jit_module_wp = jit_module_sp;
            target->GetImages().Append(jit_module_sp);
        }
    }

    ResetDeclMap(); // Make this go away since we don't need any of its state after parsing.  This also gets rid of any
                    // ClangASTImporter::Minions.

    if (process && m_jit_start_addr != LLDB_INVALID_ADDRESS)
        m_jit_process_wp = lldb::ProcessWP(process->shared_from_this());
    return true;
}

bool
ClangUserExpression::AddArguments(ExecutionContext &exe_ctx, std::vector<lldb::addr_t> &args,
                                  lldb::addr_t struct_address, DiagnosticManager &diagnostic_manager)
{
    lldb::addr_t object_ptr = LLDB_INVALID_ADDRESS;
    lldb::addr_t cmd_ptr = LLDB_INVALID_ADDRESS;

    if (m_needs_object_ptr)
    {
        lldb::StackFrameSP frame_sp = exe_ctx.GetFrameSP();
        if (!frame_sp)
            return true;
        
        ConstString object_name;

        if (m_in_cplusplus_method)
        {
            object_name.SetCString("this");
        }
        else if (m_in_objectivec_method)
        {
            object_name.SetCString("self");
        }
        else
        {
            diagnostic_manager.PutCString(eDiagnosticSeverityError, "need object pointer but don't know the language");
            return false;
        }

        Error object_ptr_error;

        object_ptr = GetObjectPointer(frame_sp, object_name, object_ptr_error);

        if (!object_ptr_error.Success())
        {
            diagnostic_manager.Printf(eDiagnosticSeverityWarning,
                                      "couldn't get required object pointer (substituting NULL): %s",
                                      object_ptr_error.AsCString());
            object_ptr = 0;
        }

        if (m_in_objectivec_method)
        {
            ConstString cmd_name("_cmd");

            cmd_ptr = GetObjectPointer(frame_sp, cmd_name, object_ptr_error);

            if (!object_ptr_error.Success())
            {
                diagnostic_manager.Printf(eDiagnosticSeverityWarning,
                                          "couldn't get cmd pointer (substituting NULL): %s",
                                          object_ptr_error.AsCString());
                cmd_ptr = 0;
            }
        }
        if (object_ptr)
            args.push_back(object_ptr);

        if (m_in_objectivec_method)
            args.push_back(cmd_ptr);

        args.push_back(struct_address);
    }
    else
    {
        args.push_back(struct_address);
    }
    return true;
}

lldb::ExpressionVariableSP
ClangUserExpression::GetResultAfterDematerialization(ExecutionContextScope *exe_scope)
{
    return m_result_delegate.GetVariable();
}

void
ClangUserExpression::ClangUserExpressionHelper::ResetDeclMap(ExecutionContext &exe_ctx, Materializer::PersistentVariableDelegate &delegate, bool keep_result_in_memory)
{
    m_expr_decl_map_up.reset(new ClangExpressionDeclMap(keep_result_in_memory, &delegate, exe_ctx));
}

clang::ASTConsumer *
ClangUserExpression::ClangUserExpressionHelper::ASTTransformer(clang::ASTConsumer *passthrough)
{
    m_result_synthesizer_up.reset(new ASTResultSynthesizer(passthrough, m_top_level, m_target));

    return m_result_synthesizer_up.get();
}

void
ClangUserExpression::ClangUserExpressionHelper::CommitPersistentDecls()
{
    if (m_result_synthesizer_up.get())
    {
        m_result_synthesizer_up->CommitPersistentDecls();
    }
}

ClangUserExpression::ResultDelegate::ResultDelegate()
{
}

ConstString
ClangUserExpression::ResultDelegate::GetName()
{
    return m_persistent_state->GetNextPersistentVariableName();
}

void
ClangUserExpression::ResultDelegate::DidDematerialize(lldb::ExpressionVariableSP &variable)
{
    m_variable = variable;
}

void
ClangUserExpression::ResultDelegate::RegisterPersistentState(PersistentExpressionState *persistent_state)
{
    m_persistent_state = persistent_state;
}

lldb::ExpressionVariableSP &
ClangUserExpression::ResultDelegate::GetVariable()
{
    return m_variable;
}