[m-rev.] diff: fix bug in simplify.m

[Simon Taylor]

Estimated hours taken: 2.5

Fix a code generator abort reported by rafe.

compiler/simplify.m:
	Recompute instmap deltas and rerun determinism analysis
	after optimizing away part of an if-then-else, to avoid
	a case where a conjunction with determinism `erroneous'
	was being given determinism `det' (which was the
	determinism of the enclosing if-then-else).

compiler/common.m:
	Rerun determininsm analysis after optimizing away a
	duplicate call or unification with determinism other
	than `det'. 

tests/valid/Mmakefile:
tests/valid/simplify_bug2.m:
	Test case.

Index: compiler/common.m
===================================================================
RCS file: /home/mercury1/repository/mercury/compiler/common.m,v
retrieving revision 1.63
diff -u -u -r1.63 common.m
--- compiler/common.m	28 Mar 2002 03:42:49 -0000	1.63
+++ compiler/common.m	14 May 2002 08:29:10 -0000
@@ -168,7 +168,7 @@
 		)
 	;
 		Unification0 = deconstruct(Var, ConsId,
-				ArgVars, UniModes, _, _),
+				ArgVars, UniModes, CanFail, _),
 		simplify_info_get_module_info(Info0, ModuleInfo),
 		(
 				% Don't optimise partially instantiated
@@ -194,10 +194,15 @@
 			OldStruct = structure(_, _, _, OldArgVars),
 			common__create_output_unifications(GoalInfo0, ArgVars,
 				OldArgVars, UniModes, Goals, Info0, Info1),
-			simplify_info_set_requantify(Info1, Info2),
 			Goal = conj(Goals),
 			pd_cost__goal(Goal0 - GoalInfo0, Cost),
-			simplify_info_incr_cost_delta(Info2, Cost, Info)
+			simplify_info_incr_cost_delta(Info1, Cost, Info2),
+			simplify_info_set_requantify(Info2, Info3),
+			( CanFail = can_fail ->
+				simplify_info_set_rerun_det(Info3, Info)
+			;	
+				Info = Info3
+			)
 		;
 			Goal = Goal0,
 			common__record_cell(Var, ConsId, ArgVars, Info0, Info)
@@ -502,7 +507,13 @@
 				Structs1, SeenCalls0),
 			pd_cost__goal(Goal0 - GoalInfo, Cost),
 			simplify_info_incr_cost_delta(Info2, Cost, Info3),
-			simplify_info_set_requantify(Info3, Info4)
+			simplify_info_set_requantify(Info3, Info4),
+			goal_info_get_determinism(GoalInfo, Detism0),
+			( Detism0 \= det ->
+				simplify_info_set_rerun_det(Info4, Info5)
+			;
+				Info5 = Info4
+			)
 		;
 			goal_info_get_context(GoalInfo, Context),
 			ThisCall = call_args(Context, InputArgs, OutputArgs),
@@ -511,7 +522,7 @@
 			CommonInfo = common(Eqv0, Structs0,
 				Structs1, SeenCalls),
 			Goal = Goal0,
-			Info4 = Info0
+			Info5 = Info0
 		)
 	;
 		goal_info_get_context(GoalInfo, Context),
@@ -519,9 +530,9 @@
 		map__det_insert(SeenCalls0, SeenCall, [ThisCall], SeenCalls),
 		CommonInfo = common(Eqv0, Structs0, Structs1, SeenCalls),
 		Goal = Goal0,
-		Info4 = Info0
+		Info5 = Info0
 	),
-	simplify_info_set_common_info(Info4, CommonInfo, Info).
+	simplify_info_set_common_info(Info5, CommonInfo, Info).
 
 %---------------------------------------------------------------------------%
 
Index: compiler/simplify.m
===================================================================
RCS file: /home/mercury1/repository/mercury/compiler/simplify.m,v
retrieving revision 1.102
diff -u -u -r1.102 simplify.m
--- compiler/simplify.m	28 Mar 2002 03:43:36 -0000	1.102
+++ compiler/simplify.m	14 May 2002 07:05:31 -0000
@@ -996,7 +996,9 @@
 			Info0, Info1),
 		goal_info_get_context(GoalInfo0, Context),
 		simplify_info_add_msg(Info1, ite_cond_cannot_fail(Context),
-			Info)
+			Info2),
+		simplify_info_set_requantify(Info2, Info3),
+		simplify_info_set_rerun_det(Info3, Info)
 	; CondSolns0 = at_most_zero ->
 		% Optimize away the condition and the `then' part.
 		det_negation_det(CondDetism0, MaybeNegDetism),
@@ -1040,14 +1042,18 @@
 			Info0, Info1),
 		goal_info_get_context(GoalInfo0, Context),
 		simplify_info_add_msg(Info1, ite_cond_cannot_succeed(Context),
-			Info)
+			Info2),
+		simplify_info_set_requantify(Info2, Info3),
+		simplify_info_set_rerun_det(Info3, Info)
 	; Else0 = disj([]) - _ ->
 		% (A -> C ; fail) is equivalent to (A, C)
 		goal_to_conj_list(Cond0, CondList),
 		goal_to_conj_list(Then0, ThenList),
 		list__append(CondList, ThenList, List),
 		simplify__goal(conj(List) - GoalInfo0, Goal - GoalInfo,
-			Info0, Info)
+			Info0, Info1),
+		simplify_info_set_requantify(Info1, Info2),
+		simplify_info_set_rerun_det(Info2, Info)
 	;
 		%
 		% recursively simplify the sub-goals,
Index: tests/valid/Mmakefile
===================================================================
RCS file: /home/mercury1/repository/tests/valid/Mmakefile,v
retrieving revision 1.101
diff -u -u -r1.101 Mmakefile
--- tests/valid/Mmakefile	9 May 2002 05:00:54 -0000	1.101
+++ tests/valid/Mmakefile	14 May 2002 07:39:18 -0000
@@ -149,6 +149,7 @@
 	semidet_disj.m \
 	shape_type.m \
 	simplify_bug.m \
+	simplify_bug2.m \
 	soln_context.m \
 	some_switch.m \
 	spurious_purity_warning.m \
@@ -301,6 +302,7 @@
 MCFLAGS-pred_with_no_modes	= --infer-all
 MCFLAGS-quantifier_warning	= --halt-at-warn
 MCFLAGS-simplify_bug		= -O-1
+MCFLAGS-simplify_bug2		= -O3
 MCFLAGS-spurious_purity_warning	= --halt-at-warn
 MCFLAGS-two_way_unif		= -O-1
 MCFLAGS-type_inf_ambig_test	= --infer-all
Index: tests/valid/simplify_bug2.m
===================================================================
RCS file: tests/valid/simplify_bug2.m
diff -N tests/valid/simplify_bug2.m
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ tests/valid/simplify_bug2.m	14 May 2002 07:39:02 -0000
@@ -0,0 +1,41 @@
+:- module simplify_bug2.
+
+:- interface.
+
+:- type type_info ---> type_info(c_pointer).
+:- type du_functor_descriptor ---> du_functor_descriptor(c_pointer).
+
+:- pred get_type_and_extra_args(type_info::in, P::in,
+	type_info::out) is det.
+
+:- implementation.
+
+:- import_module require.
+:- use_module std_util.
+
+get_type_and_extra_args(TypeInfoParams, PseudoTypeInfo, ArgTypeInfo) :-
+	( 
+		typeinfo_is_variable(PseudoTypeInfo, VarNum)
+	->
+		get_type_info_for_var(TypeInfoParams,
+			VarNum, ExpandedTypeInfo),
+		( typeinfo_is_variable(ExpandedTypeInfo, _) ->
+			error("get_type_and_extra_args: unbound type variable")
+		;
+			ArgTypeInfo = ExpandedTypeInfo
+		)
+	;
+		error("get_type_and_extra_args")
+	).
+
+:- pred get_type_info_for_var(type_info::in, int::in, type_info::out) is det.
+:- pragma no_inline(get_type_info_for_var/3).
+
+get_type_info_for_var(X, _, X).
+
+:- pred typeinfo_is_variable(T::in, int::out) is semidet.
+:- pragma no_inline(typeinfo_is_variable/2).
+
+typeinfo_is_variable(_, 42) :-
+	std_util__semidet_succeed.
+
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