Re: scheduling patch

[amacleod at cygnus dot com]

>> > + DEFPARAM(PARAM_MAX_PENDING_MEMORY_FLUSH,
>> > + 	 "max-pending-memory-flush",
>> > + 	 "The number of branches to track anti-dependancies through",
>> > + 	 12)
>> > +
>> 
>> I'd use 32, which is the number we use for the other pending lists.
>> 
>> I'd also rename this parameter to "PARAM_MAX_PENDING_LIST_LENGTH", and use
>> it for the other pending lists as well.

Changed to 32, and renamed. The difference between 12 and 32 on my machine 
was 2 seconds (1m10s v 1m12s). Without this patch,  it segfaults after
39m27s.



>> I don't know about the rest of the patch (although it seems good!, I just
>> would rather someone else review it), but you've botched the params.def
>> thing. :-)  You need to modify params.h too, and then use the
>> macro you define there in your test; right now you're testing an
>> enumeration constant.  When you look at params.h this will make sense.

Ah yes, it makes a great deal of sense :-)  Thanks.

>> > 	* params.def (PARAM_MAX_PENDING_MEMORY_FLUSH): Add parameter to 
>> > 	limit length of pending memory flush list.
>> 
>> Parameters should be documented in invoke.texi.
>> 

done.


>> This cleans up the timeout in testcase gcc.c-torture/compile/20001226-1.c
>> on ia64, and bootstraps.
>> 
>> OK to check in?, and should it also go to the 3.0 branch?

Here is the patch with the suggested changes:

Does this look more sensible? :-)

Andrew


	* params.def (PARAM_MAX_PENDING_LIST_LENGTH): Add parameter to 
	limit length of dependancy flush list.
	* params.h (MAX_PENDING_LIST_LENGTH): Define.
	* sched-int.h  (struct deps): Add pending_flush_length field.
	* sched-deps.c (flush_pending_lists): Last_pending_memory_flush now
	has 1 element in it.
	(sched_analyze): After a jump, if the pending memory flush list is too
	large, flush the pending lists.
	(init_deps): Initialize pending_flush_length to 0.
	* doc/invoke.texi (max_pending_list_length): Document parameter.


Index: params.def
===================================================================
RCS file: /cvs/gcc/egcs/gcc/params.def,v
retrieving revision 1.3.2.3
diff -c -p -r1.3.2.3 params.def
*** params.def	2001/05/01 18:56:22	1.3.2.3
--- params.def	2001/07/24 18:45:46
*************** DEFPARAM(PARAM_MAX_GCSE_MEMORY,
*** 75,80 ****
--- 75,90 ----
  	 "The maximum amount of memory to be allocated by GCSE",
  	 50 * 1024 * 1024)
  
+ /* This parameter limits the number of branch elements that the 
+    scheduler will track anti-dependancies through without resetting
+    the tracking mechanism.  Large functions with few calls or barriers 
+    can generate lists containing many 1000's of dependancies.  Generally 
+    the compiler either uses all available memory, or runs for far too long.  */
+ DEFPARAM(PARAM_MAX_PENDING_LIST_LENGTH,
+ 	 "max-pending-list-length",
+ 	 "The maximum length of scheduling's pending operations list",
+ 	 32)
+ 
  /*
  Local variables:
  mode:c
Index: params.h
===================================================================
RCS file: /cvs/gcc/egcs/gcc/params.h,v
retrieving revision 1.3.2.3
diff -c -p -r1.3.2.3 params.h
*** params.h	2001/05/01 18:56:22	1.3.2.3
--- params.h	2001/07/24 18:45:46
*************** typedef enum compiler_param
*** 92,96 ****
--- 92,99 ----
    PARAM_VALUE (PARAM_MAX_DELAY_SLOT_LIVE_SEARCH)
  #define MAX_GCSE_MEMORY \
    ((size_t) PARAM_VALUE (PARAM_MAX_GCSE_MEMORY))
+ #define MAX_PENDING_LIST_LENGTH \
+   PARAM_VALUE (PARAM_MAX_PENDING_LIST_LENGTH)
+   
  
  #endif /* PARAMS_H */
Index: sched-int.h
===================================================================
RCS file: /cvs/gcc/egcs/gcc/sched-int.h,v
retrieving revision 1.7.4.1
diff -c -p -r1.7.4.1 sched-int.h
*** sched-int.h	2001/03/01 13:16:03	1.7.4.1
--- sched-int.h	2001/07/24 18:45:46
*************** struct deps
*** 53,58 ****
--- 53,62 ----
       a function of the length of these pending lists.  */
    int pending_lists_length;
  
+   /* Length of the pending memory flush list. Large functions with no
+      calls may build up extremely large lists.  */
+   int pending_flush_length;
+ 
    /* The last insn upon which all memory references must depend.
       This is an insn which flushed the pending lists, creating a dependency
       between it and all previously pending memory references.  This creates
Index: sched-deps.c
===================================================================
RCS file: /cvs/gcc/egcs/gcc/sched-deps.c,v
retrieving revision 1.9.4.2
diff -c -p -r1.9.4.2 sched-deps.c
*** sched-deps.c	2001/05/20 20:05:25	1.9.4.2
--- sched-deps.c	2001/07/24 18:45:49
*************** the Free Software Foundation, 59 Temple 
*** 38,43 ****
--- 38,44 ----
  #include "toplev.h"
  #include "recog.h"
  #include "sched-int.h"
+ #include "params.h"
  
  extern char *reg_known_equiv_p;
  extern rtx *reg_known_value;
*************** flush_pending_lists (deps, insn, only_wr
*** 532,537 ****
--- 533,539 ----
  
    free_INSN_LIST_list (&deps->last_pending_memory_flush);
    deps->last_pending_memory_flush = alloc_INSN_LIST (insn, NULL_RTX);
+   deps->pending_flush_length = 1;
  }
  
  /* Analyze a single SET, CLOBBER, PRE_DEC, POST_DEC, PRE_INC or POST_INC
*************** sched_analyze (deps, head, tail)
*** 1242,1249 ****
  	  /* Make each JUMP_INSN a scheduling barrier for memory
               references.  */
  	  if (GET_CODE (insn) == JUMP_INSN)
! 	    deps->last_pending_memory_flush
! 	      = alloc_INSN_LIST (insn, deps->last_pending_memory_flush);
  	  sched_analyze_insn (deps, PATTERN (insn), insn, loop_notes);
  	  loop_notes = 0;
  	}
--- 1245,1258 ----
  	  /* Make each JUMP_INSN a scheduling barrier for memory
               references.  */
  	  if (GET_CODE (insn) == JUMP_INSN)
! 	    {
! 	      /* Keep the list a reasonable size.  */
! 	      if (deps->pending_flush_length++ > MAX_PENDING_LIST_LENGTH)
! 		flush_pending_lists (deps, insn, 0);
! 	      else
! 		deps->last_pending_memory_flush
! 		  = alloc_INSN_LIST (insn, deps->last_pending_memory_flush);
! 	    }
  	  sched_analyze_insn (deps, PATTERN (insn), insn, loop_notes);
  	  loop_notes = 0;
  	}
*************** init_deps (deps)
*** 1469,1474 ****
--- 1482,1488 ----
    deps->pending_write_insns = 0;
    deps->pending_write_mems = 0;
    deps->pending_lists_length = 0;
+   deps->pending_flush_length = 0;
    deps->last_pending_memory_flush = 0;
    deps->last_function_call = 0;
    deps->in_post_call_group_p = 0;
Index: doc/invoke.texi
===================================================================
RCS file: /cvs/gcc/egcs/gcc/doc/invoke.texi,v
retrieving revision 1.3.2.20
diff -c -p -r1.3.2.20 invoke.texi
*** invoke.texi	2001/07/05 19:36:14	1.3.2.20
--- invoke.texi	2001/07/24 18:46:09
*************** order to perform the global common subex
*** 3725,3730 ****
--- 3725,3736 ----
  optimization.  If more memory than specified is required, the
  optimization will not be done.
  
+ @item max-pending-list-length
+ The maximum number of pending dependancies scheduling will allow
+ before flushing the current state and starting over. Large functions
+ with few branches or calls can create excessively large lists which
+ needlessly consume memory and resources.
+ 
  @item max-inline-insns
  If an function contains more than this many instructions, it
  will not be inlined.  This option is precisely equivalent to