Re: Edges, predictions, and GC crashes ...

[Jan Hubicka <hubicka at ucw dot cz>]

> Jan Hubicka wrote:
> 
> > I didn't have any cleanup_cfg in between earliest place putting
> > predictions and the profiling pass consuming them, so this scenario
> > didn't happen.  This has however changed a long time ago.  I guess just
> > teaching remove_edge to walk prediction list if it is present and kill
> > now dead predictions would not be perfomrance overkill as the
> > predictions are rare, I can implement that if you pass me some testcase.
> 
> FAIL: libmudflap.c++/pass57-frag.cxx (test for excess errors)
> WARNING: libmudflap.c++/pass57-frag.cxx compilation failed to produce executable
> FAIL: libmudflap.c++/pass57-frag.cxx (-static) (test for excess errors)
> WARNING: libmudflap.c++/pass57-frag.cxx (-static) compilation failed to produce executable
> FAIL: libmudflap.c++/pass57-frag.cxx (-O2) (test for excess errors)
> WARNING: libmudflap.c++/pass57-frag.cxx (-O2) compilation failed to produce executable
> FAIL: libmudflap.c++/pass57-frag.cxx (-O3) (test for excess errors)
> WARNING: libmudflap.c++/pass57-frag.cxx (-O3) compilation failed to produce executable
> 
> with current mainline on s390-ibm-linux.
> 
> Thanks for looking into this issue!

Hi,
I've comitted the attached patch.  I didn't suceed to reproduce your
failures, but Danny reported it fixes his and it bootstrap/regtests
i686-pc-gnu-linux.

Honza

2005-06-03  Jan Hubicka  <jh@suse.cz>
	* basic-block.h (remove_predictions_associated_with_edge): Declare.
	* cfg.c (remove_edge): Use it.
	* predict.c (remove_predictions_associated_with_edge): New function.
Index: basic-block.h
===================================================================
RCS file: /cvs/gcc/gcc/gcc/basic-block.h,v
retrieving revision 1.261
diff -c -3 -p -r1.261 basic-block.h
*** basic-block.h	1 Jun 2005 12:07:42 -0000	1.261
--- basic-block.h	2 Jun 2005 21:45:58 -0000
*************** extern void tree_predict_edge (edge, enu
*** 869,874 ****
--- 869,875 ----
  extern void rtl_predict_edge (edge, enum br_predictor, int);
  extern void predict_edge_def (edge, enum br_predictor, enum prediction);
  extern void guess_outgoing_edge_probabilities (basic_block);
+ extern void remove_predictions_associated_with_edge (edge);
  
  /* In flow.c */
  extern void init_flow (void);
Index: cfg.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/cfg.c,v
retrieving revision 1.92
diff -c -3 -p -r1.92 cfg.c
*** cfg.c	12 May 2005 22:32:08 -0000	1.92
--- cfg.c	2 Jun 2005 21:45:58 -0000
*************** make_single_succ_edge (basic_block src, 
*** 349,354 ****
--- 349,355 ----
  void
  remove_edge (edge e)
  {
+   remove_predictions_associated_with_edge (e);
    execute_on_shrinking_pred (e);
  
    disconnect_src (e);
Index: predict.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/predict.c,v
retrieving revision 1.146
diff -c -3 -p -r1.146 predict.c
*** predict.c	27 May 2005 22:06:33 -0000	1.146
--- predict.c	2 Jun 2005 21:45:58 -0000
*************** tree_predict_edge (edge e, enum br_predi
*** 240,245 ****
--- 240,263 ----
    i->edge = e;
  }
  
+ /* Remove all predictions on given basic block that are attached
+    to edge E.  */
+ void
+ remove_predictions_associated_with_edge (edge e)
+ {
+   if (e->src->predictions)
+     {
+       struct edge_prediction **prediction = &e->src->predictions;
+       while (*prediction)
+ 	{
+ 	  if ((*prediction)->edge == e)
+ 	    *prediction = (*prediction)->next;
+ 	  else
+ 	    prediction = &((*prediction)->next);
+ 	}
+     }
+ }
+ 
  /* Return true when we can store prediction on insn INSN.
     At the moment we represent predictions only on conditional
     jumps, not at computed jump or other complicated cases.  */