[m-dev.] for review: fix a code gen bug

[David Overton]

Estimated hours taken: 10

compiler/code_info.m:
	In code_info__place_vars, place references in their required
	locations as well as values.  This bug was causing the else
	branch of an if_then_else to get the wrong locations for
	references to variables.  The test case for this is
	vn_block__split_at_next_ctrl_instr/4 which was being compiled
	incorrectly with --optimize-constructor-last-call turned on.

Index: code_info.m
===================================================================
RCS file: /home/mercury1/repository/mercury/compiler/code_info.m,v
retrieving revision 1.211.2.21
diff -u -r1.211.2.21 code_info.m
--- 1.211.2.21	1999/05/05 01:22:57
+++ code_info.m	1999/06/03 07:22:46
@@ -3087,15 +3087,19 @@
 
 code_info__place_vars([], empty) --> [].
 code_info__place_vars([V - Rs | RestList], Code) -->
-	(
-		{ set__to_sorted_list(Rs, VList) },
-		{ list__filter_map(code_exprn__value_to_rval, VList, RList) },
-		{ code_info__lval_in_rval_list(L, RList) }
-	->
-		code_info__place_var(V, L, ThisCode)
+	{ set__to_sorted_list(Rs, VList) },
+	{ list__filter_map(code_exprn__value_to_rval, VList, RList, RefList) },
+	( { code_info__lval_in_rval_list(L, RList) } ->
+		code_info__place_var(V, L, ValueCode)
+	;
+		{ ValueCode = empty }
+	),
+	( { RefList = [reference(RefLval) | _] } ->
+		code_info__place_var_reference(V, RefLval, ReferenceCode)
 	;
-		{ ThisCode = empty }
+		{ ReferenceCode = empty }
 	),
+	{ ThisCode = tree(ValueCode, ReferenceCode) },
 	code_info__place_vars(RestList, RestCode),
 	{ Code = tree(ThisCode, RestCode) }.
-- 
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
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