[m-rev.] diff: fix a bug in ite generation in erlang backend

[Peter Wang]

Estimated hours taken: 2
Branches: main

Fix a bug in the generation of if-then-else goals in the Erlang backend.
The calculation of the variables bound by the then branch was wrong for
model_semi conditions -- it included variables bound in the condition.

compiler/erl_code_gen.m:
	Fix the calculation of variables bound by then branches.

tests/valid/Mmakefile:
tests/valid/erl_ite_vars.m:
	Add test case.


Index: compiler/erl_code_gen.m
===================================================================
RCS file: /home/mercury/mercury1/repository/mercury/compiler/erl_code_gen.m,v
retrieving revision 1.26
diff -u -r1.26 erl_code_gen.m
--- compiler/erl_code_gen.m	27 Aug 2007 06:07:36 -0000	1.26
+++ compiler/erl_code_gen.m	3 Oct 2007 03:29:49 -0000
@@ -1042,10 +1042,9 @@
         CondCodeModel = model_semi,
 
         % Find the non-local variables bound in the condition.
-        % The instmap before Then should really be
-        % InstMap0 + instmap_delta(Cond) but this is okay.
         erl_bound_nonlocals_in_goal(!.Info, InstMap0, Cond, CondVars),
-        erl_bound_nonlocals_in_goal(!.Info, InstMap0, Then, ThenVars),
+        update_instmap(Cond, InstMap0, InstMap0PostCond),
+        erl_bound_nonlocals_in_goal(!.Info, InstMap0PostCond, Then, ThenVars),
         erl_bound_nonlocals_in_goal(!.Info, InstMap0, Else, ElseVars),
         CondVarsList = set.to_sorted_list(CondVars),
 
Index: tests/valid/Mmakefile
===================================================================
RCS file: /home/mercury/mercury1/repository/tests/valid/Mmakefile,v
retrieving revision 1.195
diff -u -r1.195 Mmakefile
--- tests/valid/Mmakefile	17 Sep 2007 07:16:09 -0000	1.195
+++ tests/valid/Mmakefile	3 Oct 2007 03:29:48 -0000
@@ -82,6 +82,7 @@
 	easy_nondet_test_2 \
 	empty_bound_inst_list \
 	empty_switch \
+	erl_ite_vars \
 	error \
 	eval \
 	existential_cons \
Index: tests/valid/erl_ite_vars.m
===================================================================
RCS file: tests/valid/erl_ite_vars.m
diff -N tests/valid/erl_ite_vars.m
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ tests/valid/erl_ite_vars.m	3 Oct 2007 03:29:49 -0000
@@ -0,0 +1,36 @@
+% This is a regression test for a bug in the generation of if-then-else goals
+% in the Erlang backend.  The calculation of the variables bound by the then
+% branch was wrong -- it included variables bound in the condition.
+
+:- module erl_ite_vars.
+:- interface.
+
+:- import_module list.
+
+:- type baz
+    --->    and(baz, baz)
+    ;	    bar(string)
+    ;	    quux(string).
+
+:- pred foo(list(string)::in, list(string)::out, baz::out) is semidet.
+
+:- implementation.
+
+foo(List, Rest, Expression):-
+    ( List = ["(", "(" | R] ->
+        foo(["(" | R], Rem, Exp)
+    ;
+        List = ["(", "bar", Name | _], 
+        Rem = [],
+        Exp = bar(Name)
+    ;
+        List = ["(", "quux", Name, ")" | Rem], 
+        Exp = quux(Name)
+    ),
+    ( Rem = ["," | Next] ->
+        foo(Next, Rest, RestExp),
+        Expression = and(Exp, RestExp)
+    ;   
+        Rest = [],
+        Expression = Exp
+    ).

--------------------------------------------------------------------------
mercury-reviews mailing list
Post messages to:       mercury-reviews at csse.unimelb.edu.au
Administrative Queries: owner-mercury-reviews at csse.unimelb.edu.au
Subscriptions:          mercury-reviews-request at csse.unimelb.edu.au
--------------------------------------------------------------------------