[m-rev.] [reuse] diff: unconditional reuses (bugfix)

[Nancy Mazur]

Hi,


===================================================================


Estimated hours taken: 1

Bugfix. If a procedure has conditional reuse, it is split up into 2
versions: a version having all reuse, and a version having all
unconditional reuse (i.e. reuse which is always safe to do,
independent of the caller). Even if a reuse has no conditional reuse, the
version is still processed to allow all unconditional reuse. 
When introducing the concept of "potential_reuse" as an extra step 
before the actual reuses, things went wrong, and the unconditional
reuses in the versions with pure unconditional reuses, were not
marked as actual reuses, hence missing a huge part of all the
reuses. 
Solution: when a reuse is known to be unconditional, don't go mark
it as "potential reuse", but directly as a plain reuse tout-court. 

sr_choice_graphing.m:
sr_indirect.m:
	When reuse is detected, check whether it is conditional 
	or not. If yes: produce a potential_reuse(...), or else, 
	simply move on to reuse(...). 


Index: sr_choice_graphing.m
===================================================================
RCS file: /home/mercury1/repository/mercury/compiler/Attic/sr_choice_graphing.m,v
retrieving revision 1.1.2.2
diff -u -r1.1.2.2 sr_choice_graphing.m
--- sr_choice_graphing.m	2001/07/06 09:42:25	1.1.2.2
+++ sr_choice_graphing.m	2001/08/16 17:05:56
@@ -742,11 +742,22 @@
 				Cond = condition(_,_,_),
 				Conditional = yes
 			),
-			goal_info_set_reuse(I0, 
-				potential_reuse(cell_reused(
-					DeadContextVar ^ pvar, 
+			CellReused = cell_reused( DeadContextVar ^ pvar, 
 					Conditional,
-					ConsIds, ReuseFields)), I), 
+					ConsIds, ReuseFields),
+			(
+				Conditional = yes, 
+				KindReuse = potential_reuse(CellReused)
+			; 
+				Conditional = no, 
+				% If the reuse is unconditional, then
+				% reuse is not just potentially possible, 
+				% but alwasy possible, so skipping the
+				% potential phase is perfectly safe. 
+				% (see also sr_indirect__call_verify_reuse)
+				KindReuse = reuse(CellReused)
+			), 	
+			goal_info_set_reuse(I0, KindReuse, I), 
 			E = E0
 		;
 			% ReuseVars = [_|_]
Index: sr_indirect.m
===================================================================
RCS file: /home/mercury1/repository/mercury/compiler/Attic/sr_indirect.m,v
retrieving revision 1.1.2.25
diff -u -r1.1.2.25 sr_indirect.m
--- sr_indirect.m	2001/06/22 14:46:59	1.1.2.25
+++ sr_indirect.m	2001/08/16 17:05:57
@@ -513,10 +513,21 @@
 			indirect_reuse_pool_add(HLDS, ProcInfo,
 				Memo, LFUi, LBUi, 
 				Alias0, ConditionalReuse, Pool0, Pool),
-			goal_info_set_reuse(Info0,
-					potential_reuse(
-						reuse_call(ConditionalReuse)),
-					Info),
+			ReuseCall = reuse_call(ConditionalReuse),
+			(
+				ConditionalReuse = yes,
+				KindReuse = potential_reuse(ReuseCall)
+			;
+				ConditionalReuse = no, 
+				% If the reuse is unconditional, then
+				% reuse is not just potentially possible, 
+				% but alwasy possible, so skipping the
+				% potential phase is perfectly safe. 
+				% (see also
+				% sr_choice_graphing__annotate_reuses)
+				KindReuse = reuse(ReuseCall)
+			),
+			goal_info_set_reuse(Info0, KindReuse, Info),
 			YesNo = yes
 		;
 			Pool = Pool0,

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