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References: <bug-44095-7665@http.gcc.gnu.org/bugzilla/>
Subject: [Bug java/44095] [4.5/4.6 Regression] massive java failures due to -findirect-dispatch breakage on sparc64-linux
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From: "ebotcazou at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org>
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------- Comment #3 from ebotcazou at gcc dot gnu dot org  2010-09-21 21:45 -------
> Java is severely broken on sparc64-linux with gcc 4.5/4.6, which is a major
> regression from 4.4:
> 
> http://gcc.gnu.org/ml/gcc-testresults/2010-05/msg00853.html (4.6 broken)
> http://gcc.gnu.org/ml/gcc-testresults/2010-05/msg00681.html (4.5 broken)
> http://gcc.gnu.org/ml/gcc-testresults/2010-05/msg00472.html (4.4 works)
> 
> The detailed test suite logs show that _every_ -findirect-dispatch test case
> SEGFAULTs shortly after startup.
> 
> I've bisected trunk and identified r155622 as the cause:
> 
> Author: jakub
> Date: Mon Jan  4 16:02:41 2010
> New Revision: 155622
> 
> URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=155622
> Log:
>         PR driver/42442
>         * gcc.c (SWITCH_IGNORE_PERMANENTLY): Define.
>         (do_self_spec): For switches with SWITCH_IGNORE set set also
>         SWITCH_IGNORE_PERMANENTLY.
>         (check_live_switch): Check SWITCH_IGNORE_PERMANENTLY instead
>         of SWITCH_IGNORE.
>
> [...]
>
> The main difference is that in the working compiler, the java classes are
> assembled with -K PIC but the generated main() is not, while in the broken
> compiler both the java classes and the generated main() are assembled with -K
> PIC.

Thanks for the detailed analysis.

> I note that gcc/java/jvspec.c has %<findirect-dispatch, and that PR42442 is
> about correcting the handling of %<match=native.  Clearly something here
> doesn't mix well.

My interpretation is that the %<findirect-dispatch for cc1 used to cancel the
effect of -findirect-dispatch for subsequent programs invoked by the driver, in
particular 'as' in this case.  Jakub's change disables this cancellation so
-findirect-dispatch is passed to 'as' and thus the kludge I put in ASM_SPEC for
Linux triggers, which breaks because cc1 hasn't compiled the file in PIC mode.


-- 

ebotcazou at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|2010-09-20 21:40:00         |2010-09-21 21:45:21
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44095