[Lldb-commits] [lldb] r264474 - Add a 'language cplusplus demangle' command. This can be useful to provide a low-friction reproduction for issues with the LLDB demangling of C++ symbols

Enrico Granata via lldb-commits lldb-commits at lists.llvm.org
Fri Mar 25 16:59:32 PDT 2016


> On Mar 25, 2016, at 4:54 PM, Zachary Turner <zturner at google.com> wrote:
> 
> Ahh, I didn't notice that our C++ Language Runtime is already called the Itanium ABI Runtime.  Kind of unfortunate.

Not necessarily. The demangling is - indeed - ABI independent (or, rather, Mangled.cpp can demangle both MSVC and Itanium manglings); but I imagine dynamic type discovery/exception handling would be different on the MSVC ABI. I think the name makes sense. Someone would just need to implement a language runtime for the MSVC ABI, and then choose which one to load depending on what ABI/runtime the process is targeting.

> 
> I wonder how it would work if a process had modules loaded with different languages.  Right now we seem to assume 1 language runtime

per language

> per process, but really it's more like 1 per module.

The language runtimes are actually meant to be per-process since they actually respond to dynamic “runtime”-y in nature questions.

The mixing of languages already works today, e.g. we support processes that have both Swift and Objective-C code, and questions get dispatched to the proper runtime.

> 
> On Fri, Mar 25, 2016 at 4:49 PM Enrico Granata <egranata at apple.com <mailto:egranata at apple.com>> wrote:
>> On Mar 25, 2016, at 4:39 PM, Zachary Turner <zturner at google.com <mailto:zturner at google.com>> wrote:
>> 
>> Any particular reason this has the word Itanium baked into the name of the class
> 
> The name of the C++ language runtime is ItaniumABI
> I don’t think we have a language runtime for the C++ MSVC ABI
> We can revisit where this command lives at that time
> 
>> and description?
> 
> It shouldn’t - it should be “language cplusplus demangle”, no mention of Itanium
> If you are referring to the description of the plugin overall, that is correct, and should stay as-is
> 
> Again, the hierarchy can be revisited when a C++ MSVC ABI runtime plugin exists.
> 
>>   MSVC doesn't use the Itanium ABI, but but AFAICT from looking at this code, it should work for MSVC's abi as well.  
>> 
> 
> I have no way to test it, but I would assume so, yes.
> 
>> Sicne this command isn't actually Itanium ABI specific, I don't think it should make references to Itanium ABI in its C++ class name
> 
> This seems nitpicking to me, since the entire file is named ItaniumABILanguageRuntime.cpp
> 
>> or help / description
> 
> I don’t think it does
> 
>> 
>> On Fri, Mar 25, 2016 at 4:19 PM Enrico Granata via lldb-commits <lldb-commits at lists.llvm.org <mailto:lldb-commits at lists.llvm.org>> wrote:
>> Author: enrico
>> Date: Fri Mar 25 18:14:24 2016
>> New Revision: 264474
>> 
>> URL: http://llvm.org/viewvc/llvm-project?rev=264474&view=rev <http://llvm.org/viewvc/llvm-project?rev=264474&view=rev>
>> Log:
>> Add a 'language cplusplus demangle' command. This can be useful to provide a low-friction reproduction for issues with the LLDB demangling of C++ symbols
>> 
>> Modified:
>>     lldb/trunk/source/Plugins/LanguageRuntime/CPlusPlus/ItaniumABI/ItaniumABILanguageRuntime.cpp
>> 
>> Modified: lldb/trunk/source/Plugins/LanguageRuntime/CPlusPlus/ItaniumABI/ItaniumABILanguageRuntime.cpp
>> URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Plugins/LanguageRuntime/CPlusPlus/ItaniumABI/ItaniumABILanguageRuntime.cpp?rev=264474&r1=264473&r2=264474&view=diff <http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Plugins/LanguageRuntime/CPlusPlus/ItaniumABI/ItaniumABILanguageRuntime.cpp?rev=264474&r1=264473&r2=264474&view=diff>
>> ==============================================================================
>> --- lldb/trunk/source/Plugins/LanguageRuntime/CPlusPlus/ItaniumABI/ItaniumABILanguageRuntime.cpp (original)
>> +++ lldb/trunk/source/Plugins/LanguageRuntime/CPlusPlus/ItaniumABI/ItaniumABILanguageRuntime.cpp Fri Mar 25 18:14:24 2016
>> @@ -13,11 +13,15 @@
>>  #include "lldb/Core/ConstString.h"
>>  #include "lldb/Core/Error.h"
>>  #include "lldb/Core/Log.h"
>> +#include "lldb/Core/Mangled.h"
>>  #include "lldb/Core/Module.h"
>>  #include "lldb/Core/PluginManager.h"
>>  #include "lldb/Core/Scalar.h"
>>  #include "lldb/Core/ValueObject.h"
>>  #include "lldb/Core/ValueObjectMemory.h"
>> +#include "lldb/Interpreter/CommandObject.h"
>> +#include "lldb/Interpreter/CommandObjectMultiword.h"
>> +#include "lldb/Interpreter/CommandReturnObject.h"
>>  #include "lldb/Symbol/ClangASTContext.h"
>>  #include "lldb/Symbol/Symbol.h"
>>  #include "lldb/Symbol/SymbolFile.h"
>> @@ -340,12 +344,96 @@ ItaniumABILanguageRuntime::CreateInstanc
>>          return NULL;
>>  }
>> 
>> +class CommandObjectMultiwordItaniumABI_Demangle : public CommandObjectParsed
>> +{
>> +public:
>> +    CommandObjectMultiwordItaniumABI_Demangle (CommandInterpreter &interpreter) :
>> +    CommandObjectParsed (interpreter,
>> +                         "demangle",
>> +                         "Demangle a C++ mangled name.",
>> +                         "language cplusplus demangle")
>> +    {
>> +        CommandArgumentEntry arg;
>> +        CommandArgumentData index_arg;
>> +
>> +        // Define the first (and only) variant of this arg.
>> +        index_arg.arg_type = eArgTypeSymbol;
>> +        index_arg.arg_repetition = eArgRepeatPlus;
>> +
>> +        // There is only one variant this argument could be; put it into the argument entry.
>> +        arg.push_back (index_arg);
>> +
>> +        // Push the data for the first argument into the m_arguments vector.
>> +        m_arguments.push_back (arg);
>> +    }
>> +
>> +    ~CommandObjectMultiwordItaniumABI_Demangle() override = default;
>> +
>> +protected:
>> +    bool
>> +    DoExecute(Args& command, CommandReturnObject &result) override
>> +    {
>> +        bool demangled_any = false;
>> +        bool error_any = false;
>> +        for (size_t i = 0; i < command.GetArgumentCount(); i++)
>> +        {
>> +            auto arg = command.GetArgumentAtIndex(i);
>> +            if (arg && *arg)
>> +            {
>> +                ConstString mangled_cs(arg);
>> +
>> +                // the actual Mangled class should be strict about this, but on the command line
>> +                // if you're copying mangled names out of 'nm' on Darwin, they will come out with
>> +                // an extra underscore - be willing to strip this on behalf of the user
>> +                // This is the moral equivalent of the -_/-n options to c++filt
>> +                if (mangled_cs.GetStringRef().startswith("__Z"))
>> +                    mangled_cs.SetCString(arg+1);
>> +
>> +                Mangled mangled(mangled_cs, true);
>> +                if (mangled.GuessLanguage() == lldb::eLanguageTypeC_plus_plus)
>> +                {
>> +                    ConstString demangled(mangled.GetDisplayDemangledName(lldb::eLanguageTypeC_plus_plus));
>> +                    demangled_any = true;
>> +                    result.AppendMessageWithFormat("%s ---> %s\n", arg, demangled.GetCString());
>> +                }
>> +                else
>> +                {
>> +                    error_any = true;
>> +                    result.AppendErrorWithFormat("%s is not a valid C++ mangled name\n", arg);
>> +                }
>> +            }
>> +        }
>> +
>> +        result.SetStatus(error_any ? lldb::eReturnStatusFailed :
>> +                         (demangled_any ? lldb::eReturnStatusSuccessFinishResult : lldb::eReturnStatusSuccessFinishNoResult));
>> +        return result.Succeeded();
>> +    }
>> +};
>> +
>> +class CommandObjectMultiwordItaniumABI : public CommandObjectMultiword
>> +{
>> +public:
>> +    CommandObjectMultiwordItaniumABI (CommandInterpreter &interpreter) :
>> +    CommandObjectMultiword (interpreter,
>> +                            "cplusplus",
>> +                            "A set of commands for operating on the C++ Language Runtime.",
>> +                            "cplusplus <subcommand> [<subcommand-options>]")
>> +    {
>> +        LoadSubCommand ("demangle",   CommandObjectSP (new CommandObjectMultiwordItaniumABI_Demangle (interpreter)));
>> +    }
>> +
>> +    ~CommandObjectMultiwordItaniumABI() override = default;
>> +};
>> +
>>  void
>>  ItaniumABILanguageRuntime::Initialize()
>>  {
>>      PluginManager::RegisterPlugin (GetPluginNameStatic(),
>>                                     "Itanium ABI for the C++ language",
>> -                                   CreateInstance);
>> +                                   CreateInstance,
>> +                                   [] (CommandInterpreter& interpreter) -> lldb::CommandObjectSP {
>> +                                       return CommandObjectSP(new CommandObjectMultiwordItaniumABI(interpreter));
>> +                                   });
>>  }
>> 
>>  void
>> 
>> 
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> 
> 
> 
> Thanks,
> - Enrico
> 📩 egranata@.com ☎️ 27683
> 


Thanks,
- Enrico
📩 egranata@.com ☎️ 27683

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