Re: RFC: Putting target-dependent global state into switchable structures

[Andrew Pinski <pinskia at gmail dot com>]

On Thu, Aug 23, 2012 at 1:30 PM, Richard Sandiford
<rdsandiford@googlemail.com> wrote:
> Mike Stump <mikestump@comcast.net> writes:
>> On Jun 26, 2010, at 12:24 PM, Richard Sandiford wrote:
>>> GCC has a fair number of global variables that cache target-dependent
>>> data.  This makes it difficult to switch between subtargets on the fly,
>>> such as when switching between a MIPS16 and a non-MIPS16 function.
>>>
>>> Our current approach is to call target_reinit each time we make such
>>> a switch.  This function goes off and redoes a fair chunk of the target
>>> initialisation process, and although it works (or least worked) pretty well,
>>> it is very slow.
>>>
>>
>>>      * doc/tm.texi (SWITCHABLE_TARGET): Document.
>>>      * Makefile.in (target_globals_def): New variable.
>>>      (target_globals_h): Likewise.
>>>      (TARGET_GLOBALS_H): Likewise.
>>>      (OBJS-common): Add target-globals.o.
>>>      (gtype-desc.o): Depend on $(TARGET_GLOBALS_H).
>>>      (target-globals.o): New rule.
>>>      ($(target_globals_h)): Likewise.
>>>      (s-target-globals): Likewise.
>>>      (GTFILES): Add $(target_globals_h).
>>>      (build/gentarget-globals.o): New rule.
>>>      * defaults.h (SWITCHABLE_TARGET): Define.
>>>      * gengtype.c (open_base_files): Add target-globals.h to the
>>>      include list.
>>>      * target-globals.def: New file.
>>>      * gentarget-globals.c: Likewise.
>>>      * target-globals.c: Likewise.
>>
>> First, thanks for the work.  I have a switchable port, I seem to be seeing:
>>
>> ../../gcc/gcc/target-globals.c: In function âtarget_globals* save_target_globals()â:
>> ../../gcc/gcc/target-globals.c:69:33: error: âggc_alloc_target_globalsâ was not declared in this scope
>> make: *** [target-globals.o] Error 1
>>
>> after the switch to C++.  I was wondering if your switchable target port compiles post the switch to C++?
>
> Yeah, mips64-elf with today's trunk seems OK.  mips64-linux-gnu compiled
> relatively recently on the conversion branch too.
>
> FWIW, this was using an x86_64 host compiler bootstrapped from the
> same tree.


And I did a bootstrap right on mips64-linux-gnu right after the C++
conversion branch was merged in.

Thanks,
Andrew