llvm-project/lldb/source/Target/ObjCLanguageRuntime.cpp

//===-- ObjCLanguageRuntime.cpp ---------------------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "clang/AST/Type.h"

#include "lldb/Core/Log.h"
#include "lldb/Core/MappedHash.h"
#include "lldb/Core/Module.h"
#include "lldb/Core/PluginManager.h"
#include "lldb/Core/Timer.h"
#include "lldb/Core/ValueObject.h"
#include "lldb/Symbol/ClangASTContext.h"
#include "lldb/Symbol/SymbolContext.h"
#include "lldb/Symbol/SymbolFile.h"
#include "lldb/Symbol/Type.h"
#include "lldb/Symbol/TypeList.h"
#include "lldb/Target/ObjCLanguageRuntime.h"
#include "lldb/Target/Target.h"

#include "llvm/ADT/StringRef.h"

using namespace lldb;
using namespace lldb_private;

//----------------------------------------------------------------------
// Destructor
//----------------------------------------------------------------------
ObjCLanguageRuntime::~ObjCLanguageRuntime()
{
}

ObjCLanguageRuntime::ObjCLanguageRuntime (Process *process) :
    LanguageRuntime (process),
    m_impl_cache(),
    m_has_new_literals_and_indexing (eLazyBoolCalculate),
    m_isa_to_descriptor(),
    m_hash_to_isa_map(),
    m_type_size_cache(),
    m_isa_to_descriptor_stop_id (UINT32_MAX),
    m_complete_class_cache(),
    m_negative_complete_class_cache()
{
}

bool
ObjCLanguageRuntime::AddClass (ObjCISA isa, const ClassDescriptorSP &descriptor_sp, const char *class_name)
{
    if (isa != 0)
    {
        m_isa_to_descriptor[isa] = descriptor_sp;
        // class_name is assumed to be valid
        m_hash_to_isa_map.insert(std::make_pair(MappedHash::HashStringUsingDJB(class_name), isa));
        return true;
    }
    return false;
}

void
ObjCLanguageRuntime::AddToMethodCache (lldb::addr_t class_addr, lldb::addr_t selector, lldb::addr_t impl_addr)
{
    Log *log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_STEP));
    if (log)
    {
        log->Printf ("Caching: class 0x%" PRIx64 " selector 0x%" PRIx64 " implementation 0x%" PRIx64 ".", class_addr, selector, impl_addr);
    }
    m_impl_cache.insert (std::pair<ClassAndSel,lldb::addr_t> (ClassAndSel(class_addr, selector), impl_addr));
}

lldb::addr_t
ObjCLanguageRuntime::LookupInMethodCache (lldb::addr_t class_addr, lldb::addr_t selector)
{
    MsgImplMap::iterator pos, end = m_impl_cache.end();
    pos = m_impl_cache.find (ClassAndSel(class_addr, selector));
    if (pos != end)
        return (*pos).second;
    return LLDB_INVALID_ADDRESS;
}


lldb::TypeSP
ObjCLanguageRuntime::LookupInCompleteClassCache (ConstString &name)
{
    CompleteClassMap::iterator complete_class_iter = m_complete_class_cache.find(name);
    
    if (complete_class_iter != m_complete_class_cache.end())
    {
        // Check the weak pointer to make sure the type hasn't been unloaded
        TypeSP complete_type_sp (complete_class_iter->second.lock());
        
        if (complete_type_sp)
            return complete_type_sp;
        else
            m_complete_class_cache.erase(name);
    }
    
    if (m_negative_complete_class_cache.count(name) > 0)
        return TypeSP();
    
    const ModuleList &modules = m_process->GetTarget().GetImages();

    SymbolContextList sc_list;
    const size_t matching_symbols = modules.FindSymbolsWithNameAndType (name,
                                                                        eSymbolTypeObjCClass,
                                                                        sc_list);
    
    if (matching_symbols)
    {
        SymbolContext sc;
        
        sc_list.GetContextAtIndex(0, sc);
        
        ModuleSP module_sp(sc.module_sp);
        
        if (!module_sp)
            return TypeSP();
        
        const SymbolContext null_sc;
        const bool exact_match = true;
        const uint32_t max_matches = UINT32_MAX;
        TypeList types;

        llvm::DenseSet<SymbolFile *> searched_symbol_files;
        const uint32_t num_types = module_sp->FindTypes (null_sc,
                                                         name,
                                                         exact_match,
                                                         max_matches,
                                                         searched_symbol_files,
                                                         types);
        
        if (num_types)
        {            
            uint32_t i;
            for (i = 0; i < num_types; ++i)
            {
                TypeSP type_sp (types.GetTypeAtIndex(i));
                
                if (ClangASTContext::IsObjCObjectOrInterfaceType(type_sp->GetForwardCompilerType ()))
                {
                    if (type_sp->IsCompleteObjCClass())
                    {
                        m_complete_class_cache[name] = type_sp;
                        return type_sp;
                    }
                }
            }
        }
    }
    m_negative_complete_class_cache.insert(name);
    return TypeSP();
}

size_t
ObjCLanguageRuntime::GetByteOffsetForIvar (CompilerType &parent_qual_type, const char *ivar_name)
{
    return LLDB_INVALID_IVAR_OFFSET;
}

bool
ObjCLanguageRuntime::ClassDescriptor::IsPointerValid (lldb::addr_t value,
                                                      uint32_t ptr_size,
                                                      bool allow_NULLs,
                                                      bool allow_tagged,
                                                      bool check_version_specific) const
{
    if (!value)
        return allow_NULLs;
    if ( (value % 2) == 1  && allow_tagged)
        return true;
    if ((value % ptr_size) == 0)
        return (check_version_specific ? CheckPointer(value,ptr_size) : true);
    else
        return false;
}

ObjCLanguageRuntime::ObjCISA
ObjCLanguageRuntime::GetISA(const ConstString &name)
{
    ISAToDescriptorIterator pos = GetDescriptorIterator (name);
    if (pos != m_isa_to_descriptor.end())
        return pos->first;
    return 0;
}

ObjCLanguageRuntime::ISAToDescriptorIterator
ObjCLanguageRuntime::GetDescriptorIterator (const ConstString &name)
{
    ISAToDescriptorIterator end = m_isa_to_descriptor.end();

    if (name)
    {
        UpdateISAToDescriptorMap();
        if (m_hash_to_isa_map.empty())
        {
            // No name hashes were provided, we need to just linearly power through the
            // names and find a match
            for (ISAToDescriptorIterator pos = m_isa_to_descriptor.begin(); pos != end; ++pos)
            {
                if (pos->second->GetClassName() == name)
                    return pos;
            }
        }
        else
        {
            // Name hashes were provided, so use them to efficiently lookup name to isa/descriptor
            const uint32_t name_hash = MappedHash::HashStringUsingDJB (name.GetCString());
            std::pair <HashToISAIterator, HashToISAIterator> range = m_hash_to_isa_map.equal_range(name_hash);
            for (HashToISAIterator range_pos = range.first; range_pos != range.second; ++range_pos)
            {
                ISAToDescriptorIterator pos = m_isa_to_descriptor.find (range_pos->second);
                if (pos != m_isa_to_descriptor.end())
                {
                    if (pos->second->GetClassName() == name)
                        return pos;
                }
            }
        }
    }
    return end;
}

std::pair<ObjCLanguageRuntime::ISAToDescriptorIterator,ObjCLanguageRuntime::ISAToDescriptorIterator>
ObjCLanguageRuntime::GetDescriptorIteratorPair (bool update_if_needed)
{
    if (update_if_needed)
        UpdateISAToDescriptorMapIfNeeded();
    
    return std::pair<ObjCLanguageRuntime::ISAToDescriptorIterator,
                     ObjCLanguageRuntime::ISAToDescriptorIterator>(
                        m_isa_to_descriptor.begin(),
                        m_isa_to_descriptor.end());
}


ObjCLanguageRuntime::ObjCISA
ObjCLanguageRuntime::GetParentClass(ObjCLanguageRuntime::ObjCISA isa)
{
    ClassDescriptorSP objc_class_sp (GetClassDescriptorFromISA(isa));
    if (objc_class_sp)
    {
        ClassDescriptorSP objc_super_class_sp (objc_class_sp->GetSuperclass());
        if (objc_super_class_sp)
            return objc_super_class_sp->GetISA();
    }
    return 0;
}

ConstString
ObjCLanguageRuntime::GetActualTypeName(ObjCLanguageRuntime::ObjCISA isa)
{
    ClassDescriptorSP objc_class_sp (GetNonKVOClassDescriptor(isa));
    if (objc_class_sp)
        return objc_class_sp->GetClassName();
    return ConstString();
}

ObjCLanguageRuntime::ClassDescriptorSP
ObjCLanguageRuntime::GetClassDescriptorFromClassName (const ConstString &class_name)
{
    ISAToDescriptorIterator pos = GetDescriptorIterator (class_name);
    if (pos != m_isa_to_descriptor.end())
        return pos->second;
    return ClassDescriptorSP();

}

ObjCLanguageRuntime::ClassDescriptorSP
ObjCLanguageRuntime::GetClassDescriptor (ValueObject& valobj)
{
    ClassDescriptorSP objc_class_sp;
    // if we get an invalid VO (which might still happen when playing around
    // with pointers returned by the expression parser, don't consider this
    // a valid ObjC object)
    if (valobj.GetCompilerType().IsValid())
    {
        addr_t isa_pointer = valobj.GetPointerValue();
        if (isa_pointer != LLDB_INVALID_ADDRESS)
        {
            ExecutionContext exe_ctx (valobj.GetExecutionContextRef());
            
            Process *process = exe_ctx.GetProcessPtr();
            if (process)
            {
                Error error;
                ObjCISA isa = process->ReadPointerFromMemory(isa_pointer, error);
                if (isa != LLDB_INVALID_ADDRESS)
                    objc_class_sp = GetClassDescriptorFromISA (isa);
            }
        }
    }
    return objc_class_sp;
}

ObjCLanguageRuntime::ClassDescriptorSP
ObjCLanguageRuntime::GetNonKVOClassDescriptor (ValueObject& valobj)
{
    ObjCLanguageRuntime::ClassDescriptorSP objc_class_sp (GetClassDescriptor (valobj));
    if (objc_class_sp)
    {
        if (!objc_class_sp->IsKVO())
            return objc_class_sp;
        
        ClassDescriptorSP non_kvo_objc_class_sp(objc_class_sp->GetSuperclass());
        if (non_kvo_objc_class_sp && non_kvo_objc_class_sp->IsValid())
            return non_kvo_objc_class_sp;
    }
    return ClassDescriptorSP();
}


ObjCLanguageRuntime::ClassDescriptorSP
ObjCLanguageRuntime::GetClassDescriptorFromISA (ObjCISA isa)
{
    if (isa)
    {
        UpdateISAToDescriptorMap();
        ObjCLanguageRuntime::ISAToDescriptorIterator pos = m_isa_to_descriptor.find(isa);    
        if (pos != m_isa_to_descriptor.end())
            return pos->second;
    }
    return ClassDescriptorSP();
}

ObjCLanguageRuntime::ClassDescriptorSP
ObjCLanguageRuntime::GetNonKVOClassDescriptor (ObjCISA isa)
{
    if (isa)
    {
        ClassDescriptorSP objc_class_sp = GetClassDescriptorFromISA (isa);
        if (objc_class_sp && objc_class_sp->IsValid())
        {
            if (!objc_class_sp->IsKVO())
                return objc_class_sp;

            ClassDescriptorSP non_kvo_objc_class_sp(objc_class_sp->GetSuperclass());
            if (non_kvo_objc_class_sp && non_kvo_objc_class_sp->IsValid())
                return non_kvo_objc_class_sp;
        }
    }
    return ClassDescriptorSP();
}


CompilerType
ObjCLanguageRuntime::EncodingToType::RealizeType (const char* name, bool for_expression)
{
    if (m_scratch_ast_ctx_ap)
        return RealizeType(*m_scratch_ast_ctx_ap, name, for_expression);
    return CompilerType();
}

CompilerType
ObjCLanguageRuntime::EncodingToType::RealizeType (ClangASTContext& ast_ctx, const char* name, bool for_expression)
{
    clang::ASTContext *clang_ast = ast_ctx.getASTContext();
    if (!clang_ast)
        return CompilerType();
    return RealizeType(*clang_ast, name, for_expression);
}

ObjCLanguageRuntime::EncodingToType::~EncodingToType() {}

ObjCLanguageRuntime::EncodingToTypeSP
ObjCLanguageRuntime::GetEncodingToType ()
{
    return nullptr;
}

bool
ObjCLanguageRuntime::GetTypeBitSize (const CompilerType& compiler_type,
                                     uint64_t &size)
{
    void *opaque_ptr = compiler_type.GetOpaqueQualType();
    size = m_type_size_cache.Lookup(opaque_ptr);
    // an ObjC object will at least have an ISA, so 0 is definitely not OK
    if (size > 0)
        return true;
    
    ClassDescriptorSP class_descriptor_sp = GetClassDescriptorFromClassName(compiler_type.GetTypeName());
    if (!class_descriptor_sp)
        return false;
    
    int32_t max_offset = INT32_MIN;
    uint64_t sizeof_max = 0;
    bool found = false;
    
    for (size_t idx = 0;
         idx < class_descriptor_sp->GetNumIVars();
         idx++)
    {
        const auto& ivar = class_descriptor_sp->GetIVarAtIndex(idx);
        int32_t cur_offset = ivar.m_offset;
        if (cur_offset > max_offset)
        {
            max_offset = cur_offset;
            sizeof_max = ivar.m_size;
            found = true;
        }
    }
    
    size = 8 * (max_offset + sizeof_max);
    if (found)
        m_type_size_cache.Insert(opaque_ptr, size);
    
    return found;
}

//------------------------------------------------------------------
// Exception breakpoint Precondition class for ObjC:
//------------------------------------------------------------------
void
ObjCLanguageRuntime::ObjCExceptionPrecondition::AddClassName(const char *class_name)
{
    m_class_names.insert(class_name);
}

ObjCLanguageRuntime::ObjCExceptionPrecondition::ObjCExceptionPrecondition()
{
}

bool
ObjCLanguageRuntime::ObjCExceptionPrecondition::EvaluatePrecondition(StoppointCallbackContext &context)
{
    return true;
}

void
ObjCLanguageRuntime::ObjCExceptionPrecondition::GetDescription(Stream &stream, lldb::DescriptionLevel level)
{
}

Error
ObjCLanguageRuntime::ObjCExceptionPrecondition::ConfigurePrecondition(Args &args)
{
    Error error;
    if (args.GetArgumentCount() > 0)
        error.SetErrorString("The ObjC Exception breakpoint doesn't support extra options.");
    return error;
}