Re: [PATCH v3 7/9] compile: New 'compile print'

[Pedro Alves <palves@redhat.com>]

On 05/06/2015 08:18 PM, Jan Kratochvil wrote:
> On Wed, 06 May 2015 16:10:59 +0200, Pedro Alves wrote:
>> On 05/06/2015 01:23 PM, Jan Kratochvil wrote:
>>> This is all a hack how to get it working for live targets without implementing
>>> the compiler IR (intermediate representation) interpreter in GDB (making
>>> 'compile' commands compatible with core files). So far AFAIK C++ live
>>> functionality has been a top priority, not the IR interpreter.  This
>>> COMPILE_I_PRINT_ADDRESS_SCOPE-or-COMPILE_I_PRINT_VALUE_SCOPE conditional would
>>> be some simple runtime conditional in the IR interpreter instead.
>>>
>>> If an implementation on top of IR interpreter is required for these patches
>>> then this whole patch series should be dropped and we need to start to work on
>>> the IR interpreter instead.
>>
>> No, IR interpreter is certainly not a requirement.
> 
> IIUC in this case the hack has an acceptable scale (contrary to that printf).
> 
> 
>> But I think the comment that explains the current implementation should
>> be clear.  As is, it's just that I still don't understand what you mean by:
>>
>>>    Function returns NULL only for COMPILE_I_PRINT_ADDRESS_SCOPE when
>>>    COMPILE_I_PRINT_VALUE_SCOPE should have been used instead.
>>
>> because reading this one wonders: "OK, if COMPILE_I_PRINT_VALUE_SCOPE should
>> have been used, why wasn't it used then?  Is that a bug in the caller?"
> 
> I have put there now:
>    GDB first tries to compile the code with COMPILE_I_PRINT_ADDRESS_SCOPE.
>    If it finds user tries to print an array type this function returns
>    NULL.  Caller will then regenerate the code with
>    COMPILE_I_PRINT_VALUE_SCOPE, recompiles it again and finally runs it.
>    This is because __auto_type array-to-pointer type conversion of
>    COMPILE_I_EXPR_VAL which gets detected by COMPILE_I_EXPR_PTR_TYPE
>    preserving the array type.  */
> 

Aaaaaaaaah.  I see now.  Thanks, that's _so_ much better.

Yes, this hack is fine with me.  We have bigger fish to fry.

Let me go take a look at the new series you posted.

-- 
Pedro Alves