[m-dev.] for review: alias branch improvements [2/2]

[David Overton]

On Sun, Jul 25, 1999 at 12:28:52PM EST, Fergus Henderson wrote:
> On 23-Jul-1999, David Overton <dmo at cs.mu.OZ.AU> wrote:
> > +++ modecheck_call.m	1999/07/21 07:02:11
> ...
> > -:- pred compare_inst(inst, inst, maybe(inst), inst_table, match, module_info).
> > -:- mode compare_inst(in, in, in, in, out, in) is det.
> > +:- pred compare_inst(inst, inst, maybe(pair(inst, instmap)), inst_table,
> > +	alias_map, alias_map, match, module_info).
> > +:- mode compare_inst(in, in, in, in, in, out, out, in) is det.
> >  
> > -compare_inst(InstA, InstB, MaybeArgInst, InstTable, Result, ModuleInfo) :-
> > +compare_inst(InstA, InstB, MaybeArgInst, InstTable, AliasMap0, AliasMap,
> > +		Result, ModuleInfo) :-
> >  	% inst_matches_initial(A,B) succeeds iff
> >  	%	A specifies at least as much information
> >  	%	and at least as much binding as B --
> >  	%	with the exception that `any' matches_initial `free'
> >  	% 	and perhaps vice versa.
> > -	instmap__init_reachable(InstMapA),	% YYY
> > -	instmap__init_reachable(InstMapB),	% YYY
> > -	instmap__init_reachable(MaybeInstMap),	% YYY
> > +	instmap__init_reachable(InstMapA),
> > +	instmap__init_reachable(InstMapB),
> > +		% Empty instmaps are ok here because InstA and InstB are
> > +		% initial insts of procedures which will have no alias
> > +		% substitutions on them.
> 
> That strikes me as a fairly fragile assumption.
> Is this comment really true?

Almost.  InstA and InstB may also be the final insts of a procedure.
However, the important point is that they come from the argument_modes
field of the proc_info.

> 
> Is it an invariant that all initial insts of procedures will have no
> alias substitutions on them, or are you just assuming that this predicate
> won't be called for procedures whose initial insts have alias substitutions?

It is an invariant.  It also applies to the final insts from the
proc_info argument_modes.  There is not even an initial instmap stored
in the proc_info to allow any of these alias substitutions to be
stored.

> 
> Either way, the invariant that this predicate will only be called for
> insts which are from a procedure's initial insts is an important part
> of the interface of this predicate and it should be documented with the
> predicate declaration, not just in the body of the predicate.

ok.

> You should check all of the callers of this predicate to make sure that
> they either ensure that it holds or document the same requirement of
> their callers.

Yes, I did this.

...

> > Index: prog_data.m
> > ===================================================================
> > RCS file: /home/mercury1/repository/mercury/compiler/prog_data.m,v
> > retrieving revision 1.24.2.19
> > diff -u -u -r1.24.2.19 prog_data.m
> > --- prog_data.m	1999/07/19 01:45:22	1.24.2.19
> > +++ prog_data.m	1999/07/21 05:01:17
> > @@ -23,9 +23,7 @@
> >  % should be defined here, rather than in hlds*.m.
> >  
> >  :- import_module (inst).
> > -:- import_module hlds_data.
> > -	% YYY hlds_data needed for inst_table definition.  We should move the
> > -	% definition of inst_table somewhere else.
> > +:- import_module inst_table.
> 
> Why do prog_*.m need to import inst_table.m?

A couple of the types defined in prog_data.m contain inst_tables:

:- type types_and_modes
	--->	types_and_modes(inst_table, list(type_and_mode)).

:- type argument_modes	--->	argument_modes(inst_table, list(mode)).

These are types that Andrew added to replace `list(type_and_mode)' and
`list(mode)' in places where an inst_table is also required for the
modes to make sense (i.e. most places).  These two types are used in
several other type definitions in prog_data, e.g. for the `item' type.

I believe the reason for having inst_tables within the item type is
that it will be necessary when (and if) we allow users to specify
aliasing in mode declarations.

...

> --------------------
> 
> Apart from that, it looks fine.  Could you please send a relative
> diff when you've addressed those issues?
> 

Here it is:

--- /home/pgrad/dmo/mer0/cmp/mercury/compiler/cvslog	Mon Jul 26 11:29:15 1999
+++ ./cvslog	Mon Jul 26 11:32:04 1999
@@ -61,6 +61,8 @@
 	on the inst_table as a whole in the same module.
 	It also means that prog_data no longer needs to import
 	hlds_data just to get the definition of the inst_table type.
+	The repetitiveness of the code for inst_table_ceate_sub has been
+	reduced by using type classes.
 
 compiler/instmap.m:
 	Use other_inst_table instead of substitution_inst_table when
--- /home/pgrad/dmo/mer0/cmp/mercury/compiler/inst_match.m	Mon Jul 26 11:05:07 1999
+++ ./inst_match.m	Mon Jul 26 12:02:06 1999
@@ -359,7 +359,7 @@
 **********/
 	;
 		inst_matches_aliasing(IgnoreAliasing, InstA, InstB,
-			AliasMap0, AliasMap1),
+			InstMapA, AliasMap0, AliasMap1),
 
 		inst_expand(InstMapA, InstTable, ModuleInfo, InstA, InstA2),
 		inst_expand(InstMapB, InstTable, ModuleInfo, InstB, InstB2),
@@ -492,9 +492,12 @@
 		InstMapB, _InstTable, ModuleInfo, Expansions) :-
 	inst_table_create_sub(InstTableA, InstTableB, Sub, InstTable),
 	list__map(apply_inst_table_sub_mode(Sub), ModesB0, ModesB),
-	map__init(AliasMap0),
+
+	% Initialise alias_maps for comparing aliases between the modes.
+	map__init(AliasMapA0),
+	map__init(AliasMapB0),
 	pred_inst_argmodes_matches(ModesA, InstMapA, ModesB, InstMapB,
-		InstTable, ModuleInfo, Expansions, AliasMap0, AliasMap0).
+		InstTable, ModuleInfo, Expansions, AliasMapA0, AliasMapB0).
 
 	% pred_inst_matches_argmodes(ModesA, ModesB, ModuleInfo, Expansions):
 	% succeeds if the initial insts of ModesB specify at least as
@@ -630,19 +633,36 @@
 
 %-----------------------------------------------------------------------------%
 
-:- pred inst_matches_aliasing(bool, inst, inst, alias_map, alias_map).
-:- mode inst_matches_aliasing(in, in, in, in, out) is semidet.
+	% inst_matches_aliasing(IgnoreAliasing, InstA, InstB,
+	%		InstMapA, AliasMap0, AliasMap).
+	% 	If we are not ignoring aliasing, compare the aliasing of two
+	%	insts with respect to the current alias_map and update the
+	%	alias_map to include new aliasing information.
+	%	InstA must be at least as aliased as InstB for the predicate
+	%	to succeed.
 
-inst_matches_aliasing(yes, _, _, AliasMap, AliasMap).
-inst_matches_aliasing(no, InstA, InstB, AliasMap0, AliasMap) :-
+:- pred inst_matches_aliasing(bool, inst, inst, instmap, alias_map, alias_map).
+:- mode inst_matches_aliasing(in, in, in, in, in, out) is semidet.
+
+inst_matches_aliasing(yes, _, _, _, AliasMap, AliasMap).
+inst_matches_aliasing(no, InstA, InstB, InstMapA, AliasMap0, AliasMap) :-
 	( InstB = alias(IKB) ->
 		( map__search(AliasMap0, IKB, MaybeIK) ->
-			MaybeIK = yes(IKA),
+			% This inst_key has been seen before.
+			% Check whether InstA has a matching alias.
+			MaybeIK = yes(PrevIK),
 			InstA = alias(IKA),
+			instmap__inst_keys_are_equivalent(PrevIK, InstMapA,
+				IKA, InstMapA),
 			AliasMap = AliasMap0
 		; InstA = alias(IKA) ->
+			% Insert the new pair of corresponding inst_keys
+			% into the alias_map.
 			map__det_insert(AliasMap0, IKB, yes(IKA), AliasMap)
 		;
+			% Record that the new inst_key IKB has no corresponding
+			% inst_key in InstA.  If alias(IKB) occurs a second
+			% time, the predicate will fail.
 			map__det_insert(AliasMap0, IKB, no, AliasMap)
 		)
 	;
@@ -702,7 +722,7 @@
 		AliasMap = AliasMap0
 	;
 		inst_matches_aliasing(IgnoreAliasing, InstA, InstB,
-			AliasMap0, AliasMap1),
+			InstMapA, AliasMap0, AliasMap1),
 
 		inst_expand(InstMapA, InstTable, ModuleInfo, InstA, InstA2),
 		inst_expand(InstMapB, InstTable, ModuleInfo, InstB, InstB2),
--- /home/pgrad/dmo/mer0/cmp/mercury/compiler/inst_table.m	Mon Jul 26 11:05:07 1999
+++ ./inst_table.m	Mon Jul 26 12:09:07 1999
@@ -365,39 +365,6 @@
 		SharedInstTable, MostlyUniqInstTable, ClobberedInstTable,
 		OtherInstTable, IKT, InstTable).
 
-:- pred maybe_inst_apply_sub(inst_table_sub, maybe_inst, maybe_inst).
-:- mode maybe_inst_apply_sub(in, in, out) is det.
-
-maybe_inst_apply_sub(_, unknown, unknown).
-maybe_inst_apply_sub(Sub, known(I0), known(I)) :-
-	inst_apply_inst_table_sub(Sub, I0, I).
-
-:- pred maybe_inst_det_apply_sub(inst_table_sub, maybe_inst_det,
-		maybe_inst_det).
-:- mode maybe_inst_det_apply_sub(in, in, out) is det.
-
-maybe_inst_det_apply_sub(_, unknown, unknown).
-maybe_inst_det_apply_sub(Sub, known(I0, D), known(I, D)) :-
-	inst_apply_inst_table_sub(Sub, I0, I).
-
-:- pred merge_inst_pair_apply_sub(inst_table_sub, merge_inst_pair,
-		merge_inst_pair).
-:- mode merge_inst_pair_apply_sub(in, in, out) is det.
-
-merge_inst_pair_apply_sub(Sub, Pair0, Pair) :-
-	Pair0 = merge_inst_pair(IsLive, IA0, IB0),
-	inst_apply_inst_table_sub(Sub, IA0, IA),
-	inst_apply_inst_table_sub(Sub, IB0, IB),
-	Pair = merge_inst_pair(IsLive, IA, IB).
-
-:- pred other_inst_apply_sub(inst_table_sub, other_inst, other_inst).
-:- mode other_inst_apply_sub(in, in, out) is det.
-
-other_inst_apply_sub(Sub, other_inst(Id0, Name0), other_inst(Id, Name)) :-
-	Sub = inst_table_sub(_IKSub, IdSub),
-	Id = other_inst_id_apply_sub(IdSub, Id0),
-	inst_name_apply_sub(Sub, Name0, Name).
-
 :- pred map_apply_sub(inst_table_sub, map(K, V), map(K, V), map(K, V)) 
 		<= (inst_table_entry(K), inst_table_entry(V)).
 :- mode map_apply_sub(in, in, in, out) is det.
@@ -493,3 +460,37 @@
 inst_apply_inst_table_sub(Sub, abstract_inst(SymName, Insts0),
 		abstract_inst(SymName, Insts)) :-
 	list__map(inst_apply_inst_table_sub(Sub), Insts0, Insts).
+
+:- pred maybe_inst_apply_sub(inst_table_sub, maybe_inst, maybe_inst).
+:- mode maybe_inst_apply_sub(in, in, out) is det.
+
+maybe_inst_apply_sub(_, unknown, unknown).
+maybe_inst_apply_sub(Sub, known(I0), known(I)) :-
+	inst_apply_inst_table_sub(Sub, I0, I).
+
+:- pred maybe_inst_det_apply_sub(inst_table_sub, maybe_inst_det,
+		maybe_inst_det).
+:- mode maybe_inst_det_apply_sub(in, in, out) is det.
+
+maybe_inst_det_apply_sub(_, unknown, unknown).
+maybe_inst_det_apply_sub(Sub, known(I0, D), known(I, D)) :-
+	inst_apply_inst_table_sub(Sub, I0, I).
+
+:- pred merge_inst_pair_apply_sub(inst_table_sub, merge_inst_pair,
+		merge_inst_pair).
+:- mode merge_inst_pair_apply_sub(in, in, out) is det.
+
+merge_inst_pair_apply_sub(Sub, Pair0, Pair) :-
+	Pair0 = merge_inst_pair(IsLive, IA0, IB0),
+	inst_apply_inst_table_sub(Sub, IA0, IA),
+	inst_apply_inst_table_sub(Sub, IB0, IB),
+	Pair = merge_inst_pair(IsLive, IA, IB).
+
+:- pred other_inst_apply_sub(inst_table_sub, other_inst, other_inst).
+:- mode other_inst_apply_sub(in, in, out) is det.
+
+other_inst_apply_sub(Sub, other_inst(Id0, Name0), other_inst(Id, Name)) :-
+	Sub = inst_table_sub(_IKSub, IdSub),
+	Id = other_inst_id_apply_sub(IdSub, Id0),
+	inst_name_apply_sub(Sub, Name0, Name).
+
--- /home/pgrad/dmo/mer0/cmp/mercury/compiler/modecheck_call.m	Mon Jul 26 11:05:11 1999
+++ ./modecheck_call.m	Mon Jul 26 13:20:07 1999
@@ -781,6 +781,16 @@
 	combine_results(CompareInsts, CompareLives, Compare0),
 	prioritized_combine_results(Compare0, CompareDet, Compare).
 
+	% compare_inst_list(InstsA, InstsB, ArgInsts, InstTable, Result,
+	%		ModuleInfo)
+	%       Compare two lists of insts.  InstsA and InstsB should 
+	%       not depend on any instmap alias substitutions. Also, 
+	%       InstsA and InstsB should not share any common inst_keys. 
+	%       These preconditions are guaranteed if the inst lists are
+	%       the argument insts of two procedures (with an
+	%       appropriate application of inst_table_create_sub to
+	%       rename apart the inst_keys of the two procedures).
+
 :- pred compare_inst_list(list(inst), list(inst),
 	maybe(pair(list(inst), instmap)), inst_table, match, module_info).
 :- mode compare_inst_list(in, in, in, in, out, in) is det.
@@ -889,6 +899,15 @@
 	%	prefer ground to free	(i.e. prefer in to out)
 	% 	prefer ground to any	(e.g. prefer in to in(any))
 	% 	prefer any to free	(e.g. prefer any->ground to out)
+	%
+	% This predicate is designed to be called from compare_inst_list 
+	% which is used for comparing argument insts of two procedures. 
+	% It assumes that InstA and InstB do not depend on any instmap
+	% alias substitutions.  InstA and InstB are also required not to
+	% share any inst_keys. It also assumes that AliasMap0 will be
+	% initialised before the first call to compare_inst and the
+	% alias_map will be threaded through all calls to compare_inst
+	% for the list of insts being compared.
 
 :- pred compare_inst(inst, inst, maybe(pair(inst, instmap)), inst_table,
 	alias_map, alias_map, match, module_info).
@@ -904,8 +923,8 @@
 	instmap__init_reachable(InstMapA),
 	instmap__init_reachable(InstMapB),
 		% Empty instmaps are ok here because InstA and InstB are
-		% initial insts of procedures which will have no alias
-		% substitutions on them.
+		% assumed to be insts which have no instmap alias substitutions
+		% on them.
 	(
 		inst_matches_initial(InstA, InstMapA, InstB, InstMapB,
 			InstTable, ModuleInfo, AliasMap0, AliasMap1)
--- /home/pgrad/dmo/mer0/cmp/mercury/compiler/pd_term.m	Mon Jul 26 11:05:12 1999
+++ ./pd_term.m	Mon Jul 26 12:19:26 1999
@@ -1,5 +1,5 @@
 %-----------------------------------------------------------------------------%
-% Copyright (C) 1999 University of Melbourne.
+% Copyright (C) 1998-1999 University of Melbourne.
 % This file may only be copied under the terms of the GNU General
 % Public License - see the file COPYING in the Mercury distribution.
 %-----------------------------------------------------------------------------%
--- /home/pgrad/dmo/mer0/cmp/mercury/compiler/prog_data.m	Mon Jul 26 11:05:13 1999
+++ ./prog_data.m	Mon Jul 26 13:37:07 1999
@@ -729,17 +729,32 @@
 	;	typed_inst(type, inst_name)
 	;	other_inst(other_inst_id, inst_name).
 
+	% other_inst_id is used for distinguishing between inst_names
+	% with functor other_inst.
 :- type other_inst_id.
 
+	% other_inst_id_sub describes the substitution that needs to be applied
+	% to other_inst_ids from one procedure to allow them to be compared
+	% to other_inst_ids in another procedure.
+
 :- type other_inst_id_sub.
 
+	% Initialise the other_inst_id.
+
 :- func init_other_inst_id = other_inst_id.
 
+	% Get the next other_inst_id.
+
 :- func inc_other_inst_id(other_inst_id) = other_inst_id.
 
+	% Apply an other_inst_is_sub substitution to an other_inst_id.
+
 :- func other_inst_id_apply_sub(other_inst_id_sub, other_inst_id)
 		= other_inst_id.
 
+	% Create an other_inst_id_sub to be used for comparing other_inst_ids
+	% from different procedures.
+
 :- func other_inst_id_create_sub(other_inst_id) = other_inst_id_sub.
 
 	% Note: `is_live' records liveness in the sense used by
--- /home/pgrad/dmo/mer0/cmp/mercury/compiler/unify_proc.m	Mon Jul 26 11:05:20 1999
+++ ./unify_proc.m	Mon Jul 26 14:59:33 1999
@@ -131,7 +131,7 @@
 	% (mode number) of the unification procedure which corresponds to
 	% that mode.
 
-:- type unify_req_map == assoc_list(unify_proc_id, proc_id).
+:- type unify_req_map == map(type_id, assoc_list(unify_proc_id, proc_id)).
 
 :- type req_queue == queue(pred_proc_id).
 
@@ -146,7 +146,7 @@
 %-----------------------------------------------------------------------------%
 
 unify_proc__init_requests(Requests) :-
-	UnifyReqMap = [],
+	map__init(UnifyReqMap),
 	queue__init(ReqQueue),
 	Requests = proc_requests(UnifyReqMap, ReqQueue).
 
@@ -205,7 +205,7 @@
 
 unify_proc__search_mode_num(InstMapBefore, ModuleInfo, UnifyId, Determinism,
 		ProcId) :-
-	UnifyId = unify_proc_id(_, XInitial, YInitial, InstTable),
+	UnifyId = unify_proc_id(TypeId, XInitial, YInitial, InstTable),
 	(
 		Determinism = semidet,
 		inst_is_ground_or_any(XInitial, InstMapBefore,
@@ -225,12 +225,13 @@
 	;
 		module_info_get_proc_requests(ModuleInfo, Requests),
 		unify_proc__get_unify_req_map(Requests, UnifyReqMap),
-		unify_proc__search_mode_num_2(UnifyReqMap, UnifyId, 
+		map__search(UnifyReqMap, TypeId, UnifyProcs),
+		unify_proc__search_mode_num_2(UnifyProcs, UnifyId, 
 			InstMapBefore, ModuleInfo, ProcId)
 	).
 
-:- pred unify_proc__search_mode_num_2(unify_req_map, unify_proc_id,
-		instmap, module_info, proc_id).
+:- pred unify_proc__search_mode_num_2(assoc_list(unify_proc_id, proc_id),
+		unify_proc_id, instmap, module_info, proc_id).
 :- mode unify_proc__search_mode_num_2(in, in, in, in, out) is semidet.
 
 unify_proc__search_mode_num_2([UnifyIdA - ProcId0 | Rest], UnifyIdB,
@@ -321,7 +322,12 @@
 		%
 		module_info_get_proc_requests(ModuleInfo3, Requests0),
 		unify_proc__get_unify_req_map(Requests0, UnifyReqMap0),
-		UnifyReqMap = [UnifyId - ProcId | UnifyReqMap0],
+		( map__search(UnifyReqMap0, TypeId, UnifyProcs0) ->
+			UnifyProcs = [UnifyId - ProcId | UnifyProcs0]
+		;
+			UnifyProcs = [UnifyId - ProcId]
+		),
+		map__set(UnifyReqMap0, TypeId, UnifyProcs, UnifyReqMap),
 		unify_proc__set_unify_req_map(Requests0, UnifyReqMap, Requests),
 		module_info_set_proc_requests(ModuleInfo3, Requests,
 			ModuleInfo)
@@ -372,6 +378,20 @@
 
 %-----------------------------------------------------------------------------%
 
+	% normalise_unify_id removes all unnecessary aliases and inst_table
+	% entries from the unify_proc_id.
+	% Aliases are retained only between corresponding nodes in the
+	% inst trees of the two arguments.  Such aliases allow us to
+	% produce more efficient code for the unification procedure
+	% since, if we know that two corresponding nodes are already
+	% aliased, we don't need to produce code to unify them.
+	% (In such cases the unification goal will be replaced by conj([])
+	% during mode checking by categorize_unify_var_var).
+
+	% normalise_unify_id also removes any instmap alias substitution
+	% dependencies from the insts.  This is important since these are
+	% not allowed in the argument insts of a procedure.
+
 :- pred normalise_unify_id(instmap, module_info, unify_proc_id, unify_proc_id).
 :- mode normalise_unify_id(in, in, in, out) is det.
 
@@ -392,10 +412,10 @@
 normalise_unify_insts(InstMap, ModuleInfo, OrigInstTable, InstL0, InstL,
 		InstR0, InstR, InstTable0, InstTable) :-
 	( ( InstL0 = defined_inst(_) ; InstR0 = defined_inst(_) ) ->
-		inst_remove_aliases(InstMap, ModuleInfo, OrigInstTable,
-			InstL0, InstL, InstTable0, InstTable1),
-		inst_remove_aliases(InstMap, ModuleInfo, OrigInstTable,
-			InstR0, InstR, InstTable1, InstTable)
+		inst_remove_aliases(InstL0, InstMap, ModuleInfo, OrigInstTable,
+			InstL, InstTable0, InstTable1),
+		inst_remove_aliases(InstR0, InstMap, ModuleInfo, OrigInstTable,
+			InstR, InstTable1, InstTable)
 	;
 		normalise_unify_insts_2(InstMap, ModuleInfo, OrigInstTable,
 			InstL0, InstL, InstR0, InstR, InstTable0, InstTable)
@@ -411,13 +431,15 @@
 	(
 		InstL0 = alias(IKL)
 	->
-		( InstR0 = alias(IKR) ->
+		(
+			InstR0 = alias(IKR)
+		->
 			(
 				instmap__inst_keys_are_equivalent(IKL, InstMap,
 					IKR, InstMap)
 			->
-				inst_remove_aliases(InstMap, ModuleInfo,
-					OrigInstTable, alias(IKL), Inst,
+				inst_remove_aliases(alias(IKL), InstMap,
+					ModuleInfo, OrigInstTable, Inst,
 					InstTable0, InstTable1),
 				inst_table_get_inst_key_table(InstTable1, IKT0),
 				inst_key_table_add(IKT0, Inst, IK, IKT),
@@ -454,7 +476,9 @@
 	;
 		InstL0 = bound(UniqL, BoundInstsL0)
 	->
-		( InstR0 = bound(UniqR, BoundInstsR0) ->
+		(
+			InstR0 = bound(UniqR, BoundInstsR0)
+		->
 			normalise_unify_bound_insts(InstMap, ModuleInfo,
 				OrigInstTable, BoundInstsL0, BoundInstsL,
 				BoundInstsR0, BoundInstsR,
@@ -462,22 +486,21 @@
 			InstL = bound(UniqL, BoundInstsL),
 			InstR = bound(UniqR, BoundInstsR)
 		;
-			bound_insts_remove_aliases(InstMap, ModuleInfo,
-				OrigInstTable, BoundInstsL0, BoundInstsL,
+			bound_insts_remove_aliases(BoundInstsL0, InstMap,
+				ModuleInfo, OrigInstTable, BoundInstsL,
 				InstTable0, InstTable1),
 			InstL = bound(UniqL, BoundInstsL),
-			inst_remove_aliases(InstMap, ModuleInfo,
-				OrigInstTable, InstR0, InstR, InstTable1,
-				InstTable)
+			inst_remove_aliases(InstR0, InstMap, ModuleInfo,
+				OrigInstTable, InstR, InstTable1, InstTable)
 		)
 	;
 		InstR0 = bound(UniqR, BoundInstsR0)
 	->
-		bound_insts_remove_aliases(InstMap, ModuleInfo, OrigInstTable,
-			BoundInstsR0, BoundInstsR, InstTable0, InstTable1),
+		bound_insts_remove_aliases(BoundInstsR0, InstMap, ModuleInfo,
+			OrigInstTable, BoundInstsR, InstTable0, InstTable1),
 		InstR = bound(UniqR, BoundInstsR),
-		inst_remove_aliases(InstMap, ModuleInfo, OrigInstTable,
-			InstL0, InstL, InstTable1, InstTable)
+		inst_remove_aliases(InstL0, InstMap, ModuleInfo, OrigInstTable,
+			InstL, InstTable1, InstTable)
 	;
 		InstL0 = abstract_inst(Name, InstsL0),
 		InstR0 = abstract_inst(Name, InstsR0),
@@ -489,10 +512,10 @@
 		InstR = abstract_inst(Name, InstsR),
 		InstTable = InstTable1
 	;
-		inst_remove_aliases(InstMap, ModuleInfo, OrigInstTable,
-			InstL0, InstL, InstTable0, InstTable1),
-		inst_remove_aliases(InstMap, ModuleInfo, OrigInstTable,
-			InstR0, InstR, InstTable1, InstTable)
+		inst_remove_aliases(InstL0, InstMap, ModuleInfo, OrigInstTable,
+			InstL, InstTable0, InstTable1),
+		inst_remove_aliases(InstR0, InstMap, ModuleInfo, OrigInstTable,
+			InstR, InstTable1, InstTable)
 	).
 
 	% normalise_unify_insts fails iff the lists are different lengths.
@@ -518,11 +541,11 @@
 normalise_unify_bound_insts(InstMap, ModuleInfo, OrigInstTable, [], [],
 		BI0, BI) -->
 	{ BI0 = [_|_] },
-	bound_insts_remove_aliases(InstMap, ModuleInfo, OrigInstTable, BI0, BI).
+	bound_insts_remove_aliases(BI0, InstMap, ModuleInfo, OrigInstTable, BI).
 normalise_unify_bound_insts(InstMap, ModuleInfo, OrigInstTable, BI0, BI,
 		[], []) -->
 	{ BI0 = [_|_] },
-	bound_insts_remove_aliases(InstMap, ModuleInfo, OrigInstTable, BI0, BI).
+	bound_insts_remove_aliases(BI0, InstMap, ModuleInfo, OrigInstTable, BI).
 normalise_unify_bound_insts(InstMap, ModuleInfo, OrigInstTable,
 		[BL0 | BLs0], BLs, [BR0 | BRs0], BRs) -->
 	{ BL0 = functor(ConsIdL, ILs0) },
@@ -537,10 +560,10 @@
 			{ ILs = ILs1 },
 			{ IRs = IRs1 }
 		;
-			insts_remove_aliases(InstMap, ModuleInfo, OrigInstTable,
-				ILs0, ILs),
-			insts_remove_aliases(InstMap, ModuleInfo, OrigInstTable,
-				IRs0, IRs)
+			insts_remove_aliases(ILs0, InstMap, ModuleInfo,
+				OrigInstTable, ILs),
+			insts_remove_aliases(IRs0, InstMap, ModuleInfo,
+				OrigInstTable, IRs)
 		),
 		{ BLs = [functor(ConsIdL, ILs) | BLs1] },
 		{ BRs = [functor(ConsIdR, IRs) | BRs1] },
@@ -548,15 +571,15 @@
 			BLs0, BLs1, BRs0, BRs1)
 	;
 		{ Comp = (<) },
-		insts_remove_aliases(InstMap, ModuleInfo, OrigInstTable,
-			ILs0, ILs),
+		insts_remove_aliases(ILs0, InstMap, ModuleInfo, OrigInstTable,
+			ILs),
 		{ BLs = [functor(ConsIdL, ILs) | BLs1] },
 		normalise_unify_bound_insts(InstMap, ModuleInfo, OrigInstTable,
 			BLs0, BLs1, [BR0 | BRs0], BRs)
 	;
 		{ Comp = (>) },
-		insts_remove_aliases(InstMap, ModuleInfo, OrigInstTable,
-			IRs0, IRs),
+		insts_remove_aliases(IRs0, InstMap, ModuleInfo, OrigInstTable,
+			IRs),
 		{ BRs = [functor(ConsIdR, IRs) | BRs1] },
 		normalise_unify_bound_insts(InstMap, ModuleInfo, OrigInstTable,
 			[BL0 | BLs0], BLs, BRs0, BRs1)
@@ -565,34 +588,34 @@
 
 %-----------------------------------------------------------------------------%
 
-:- pred inst_remove_aliases(instmap, module_info, inst_table, inst, inst,
+:- pred inst_remove_aliases(inst, instmap, module_info, inst_table, inst,
 		inst_table, inst_table).
 :- mode inst_remove_aliases(in, in, in, in, out, in, out) is det.
 
 
-inst_remove_aliases(_, _, _, any(U), any(U), IT, IT).
-inst_remove_aliases(_, _, _, free(A), free(A), IT, IT).
-inst_remove_aliases(_, _, _, free(A, T), free(A, T), IT, IT).
-inst_remove_aliases(_, _, _, ground(U, P), ground(U, P), IT, IT).
-inst_remove_aliases(_, _, _, not_reached, not_reached, IT, IT).
-inst_remove_aliases(_, _, _, inst_var(V), inst_var(V), IT, IT).
-inst_remove_aliases(InstMap, ModuleInfo, OrigInstTable, alias(IK), Inst,
+inst_remove_aliases(any(U), _, _, _, any(U), IT, IT).
+inst_remove_aliases(free(A), _, _, _, free(A), IT, IT).
+inst_remove_aliases(free(A, T), _, _, _, free(A, T), IT, IT).
+inst_remove_aliases(ground(U, P), _, _, _, ground(U, P), IT, IT).
+inst_remove_aliases(not_reached, _, _, _, not_reached, IT, IT).
+inst_remove_aliases(inst_var(V), _, _, _, inst_var(V), IT, IT).
+inst_remove_aliases(alias(IK), InstMap, ModuleInfo, OrigInstTable, Inst,
 		InstTable0, InstTable) :-
 	inst_table_get_inst_key_table(OrigInstTable, IKT),
 	instmap__inst_key_table_lookup(InstMap, IKT, IK, Inst0),
-	inst_remove_aliases(InstMap, ModuleInfo, OrigInstTable, Inst0, Inst,
+	inst_remove_aliases(Inst0, InstMap, ModuleInfo, OrigInstTable, Inst,
 		InstTable0, InstTable).
-inst_remove_aliases(InstMap, ModuleInfo, OrigInstTable,
-		abstract_inst(Name, Insts0), abstract_inst(Name, Insts),
+inst_remove_aliases(abstract_inst(Name, Insts0), InstMap, ModuleInfo,
+		OrigInstTable, abstract_inst(Name, Insts),
 		InstTable0, InstTable) :-
-	insts_remove_aliases(InstMap, ModuleInfo, OrigInstTable, Insts0, Insts,
+	insts_remove_aliases(Insts0, InstMap, ModuleInfo, OrigInstTable, Insts,
 		InstTable0, InstTable).
-inst_remove_aliases(InstMap, ModuleInfo, OrigInstTable, bound(U, BoundInsts0),
+inst_remove_aliases(bound(U, BoundInsts0), InstMap, ModuleInfo, OrigInstTable,
 		bound(U, BoundInsts), InstTable0, InstTable) :-
-	bound_insts_remove_aliases(InstMap, ModuleInfo, OrigInstTable,
-		BoundInsts0, BoundInsts, InstTable0, InstTable).
-inst_remove_aliases(InstMap, ModuleInfo, OrigInstTable,
-		defined_inst(InstName0), Inst, InstTable0, InstTable) :-
+	bound_insts_remove_aliases(BoundInsts0, InstMap, ModuleInfo,
+		OrigInstTable, BoundInsts, InstTable0, InstTable).
+inst_remove_aliases(defined_inst(InstName0), InstMap, ModuleInfo,
+		OrigInstTable, Inst, InstTable0, InstTable) :-
 	inst_table_get_other_insts(InstTable0, OtherInsts0),
 	other_inst_table_mark_inst_name(OtherInsts0, InstName0, InstName),
 	( other_inst_table_search(OtherInsts0, InstName0, MaybeInst) ->
@@ -610,8 +633,8 @@
 		inst_lookup(OrigInstTable, ModuleInfo, InstName0, Inst0),
 		inst_expand_defined_inst(OrigInstTable, ModuleInfo, Inst0,
 			Inst1),
-		inst_remove_aliases(InstMap, ModuleInfo, OrigInstTable,
-			Inst1, Inst2, InstTable1, InstTable2),
+		inst_remove_aliases(Inst1, InstMap, ModuleInfo, OrigInstTable,
+			Inst2, InstTable1, InstTable2),
 
 		inst_table_get_other_insts(InstTable2, OtherInsts2),
 		other_inst_table_set(OtherInsts2, InstName0, known(Inst2),
@@ -635,25 +658,25 @@
 		Inst = Inst2
 	).
 
-:- pred insts_remove_aliases(instmap, module_info, inst_table,
-		list(inst), list(inst), inst_table, inst_table).
+:- pred insts_remove_aliases(list(inst), instmap, module_info, inst_table,
+		list(inst), inst_table, inst_table).
 :- mode insts_remove_aliases(in, in, in, in, out, in, out) is det.
 
-insts_remove_aliases(_, _, _, [], []) --> [].
-insts_remove_aliases(InstMap, ModuleInfo, OrigInstTable, [I0 | Is0], [I | Is])
+insts_remove_aliases([], _, _, _, []) --> [].
+insts_remove_aliases([I0 | Is0], InstMap, ModuleInfo, OrigInstTable, [I | Is])
 		-->
-	inst_remove_aliases(InstMap, ModuleInfo, OrigInstTable, I0, I),
-	insts_remove_aliases(InstMap, ModuleInfo, OrigInstTable, Is0, Is).
+	inst_remove_aliases(I0, InstMap, ModuleInfo, OrigInstTable, I),
+	insts_remove_aliases(Is0, InstMap, ModuleInfo, OrigInstTable, Is).
 
-:- pred bound_insts_remove_aliases(instmap, module_info, inst_table,
-		list(bound_inst), list(bound_inst), inst_table, inst_table).
+:- pred bound_insts_remove_aliases(list(bound_inst), instmap, module_info,
+		inst_table, list(bound_inst), inst_table, inst_table).
 :- mode bound_insts_remove_aliases(in, in, in, in, out, in, out) is det.
 
-bound_insts_remove_aliases(_, _, _, [], []) --> [].
-bound_insts_remove_aliases(InstMap, ModuleInfo, OrigInstTable,
-		[functor(C, Is0) | Bs0], [functor(C, Is) | Bs]) -->
-	insts_remove_aliases(InstMap, ModuleInfo, OrigInstTable, Is0, Is),
-	bound_insts_remove_aliases(InstMap, ModuleInfo, OrigInstTable, Bs0, Bs).
+bound_insts_remove_aliases([], _, _, _, []) --> [].
+bound_insts_remove_aliases([functor(C, Is0) | Bs0], InstMap, ModuleInfo,
+		OrigInstTable, [functor(C, Is) | Bs]) -->
+	insts_remove_aliases(Is0, InstMap, ModuleInfo, OrigInstTable, Is),
+	bound_insts_remove_aliases(Bs0, InstMap, ModuleInfo, OrigInstTable, Bs).
 
 %-----------------------------------------------------------------------------%
 
-- 
David Overton       Department of Computer Science & Software Engineering
MEngSc Student      The University of Melbourne, Australia
+61 3 9344 9159     http://www.cs.mu.oz.au/~dmo
--------------------------------------------------------------------------
mercury-developers mailing list
Post messages to:       mercury-developers at cs.mu.oz.au
Administrative Queries: owner-mercury-developers at cs.mu.oz.au
Subscriptions:          mercury-developers-request at cs.mu.oz.au
--------------------------------------------------------------------------