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

[Jan Kratochvil <jan.kratochvil@redhat.com>]

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.  */

Plus at:
enum compile_i_scope_types
       name already specifies its address.  See get_out_value_type.  */
    COMPILE_I_PRINT_ADDRESS_SCOPE,
    COMPILE_I_PRINT_VALUE_SCOPE, 


Jan