Re: Ada bootstrap failure due to new DCE bug

[Diego Novillo <dnovillo at redhat dot com>]

On Mon, 2004-08-02 at 23:12, Richard Kenner wrote:
> This popped up sometime in the last few days.
> 
> When compiling Increment_Serial_Number in ada/lib.adb, we drop an
> assignment:
> 
> *** lib.adb.t24.redphi1	2004-08-02 23:02:05.000000000 -0400
> --- lib.adb.t25.dce2	2004-08-02 23:02:05.000000000 -0400
> *************** Lib.Increment_Serial_Number ()
> *** 4481,4502 ****
>   
>   <bb 0>:
>     lib__units__table.716_2 = lib__units__table;
>     lib__current_sem_unit.717_4 = lib__current_sem_unit;
>     T.718_6 = (<unnamed type>) lib__current_sem_unit.717_4;
>     tsn_7 = &(*lib__units__table.716_2)[T.718_6].serial_number;
>     T.719_8 = *tsn_7;
>     T.720_9 = (types__TintB) T.719_8;
>     T.721_10 = T.720_9 + 1;
>     T.722_11 = (types__nat___XDLU_0__2147483647) T.721_10;
> -   *tsn_7 = T.722_11;
> -   T.723_12 = T.722_11;
>     return T.722_11;
>   
>   }
>   
Hmm, I'm not seeing this anymore.  With the testcase you sent I get:


--- tbg0803.adb.t24.redphi1     2004-08-09 17:09:39.000000000 -0400
+++ tbg0803.adb.t25.dce2        2004-08-09 17:09:39.000000000 -0400
@@ -55,15 +55,12 @@ Tbg0803.Sub1 ()
   __gnat_rcheck_05 ("tbg0803.adb", 3);

 <L3>:;
-  tbg0803__unit_table.4_7 = tbg0803__unit_table.0_2;
-  tbg0803__utn.5_8 = tbg0803__utn.1_4;
   sn_9 = &(*tbg0803__unit_table.0_2)[tbg0803__utn.1_4]{lb: 1 sz: 12}.serial_number;
   #   VUSE <tbg0803__utn_3>;
   T.6_10 = *sn_9;
   T.7_11 = T.6_10 + 1;
   #   tbg0803__utn_14 = V_MAY_DEF <tbg0803__utn_3>;
   *sn_9 = T.7_11;
-  T.8_12 = T.7_11;
   return T.7_11;

 }

But I can't build gnatlib today.  I get:

../../xgcc -B../../ -c -g -O2      -gnatpg -nostdinc  g-socket.adb -o g-socket.o
+===========================GNAT BUG DETECTED==============================+
| 3.5.0 20040810 (experimental) (i686-pc-linux-gnu) GCC error:             |
| in get_indirect_ref_operands, at tree-ssa-operands.c:1224                |
| Error detected at g-socket.adb:2211:1                                    |
| Please submit a bug report; see http://gcc.gnu.org/bugs.html.            |
| Include the entire contents of this bug box in the report.               |
| Include the exact gcc or gnatmake command that you entered.              |
| Also include sources listed below in gnatchop format                     |
| (concatenated together with no headers between files).                   |
+==========================================================================+

Please include these source files with error report
Note that list may not be accurate in some cases,
so please double check that the problem can still
be reproduced with the set of files listed.



Execution terminated by unhandled exception
Exception name: TYPES.UNRECOVERABLE_ERROR
Message: comperr.adb:376


Diego.