diff: disable duplicate call optimization

[Fergus Henderson]

The following change addresses the bug that I recently reported to
mercury-bugs.

--------------------

compiler/options.m:
	Disable duplicate call optimization, because it is buggy.
	(Also add a comment about options for internal use only.)

tests/hard_coded/Mmakefile:
tests/hard_coded/dupcall_types_bug.m:
tests/hard_coded/dupcall_types_bug.exp:
	Add a regression test for the bug in duplicate call optimization.

Index: compiler/options.m
===================================================================
RCS file: /home/mercury1/repository/mercury/compiler/options.m,v
retrieving revision 1.232
diff -u -r1.232 options.m
--- options.m	1998/06/09 02:14:13	1.232
+++ options.m	1998/06/22 00:55:13
@@ -142,8 +142,13 @@
 				% `--tags high' and doesn't specify
 				% `--num-tag-bits'.
 		;	args
+		;	highlevel_c
+		;	unboxed_float
 		;	sync_term_size % in words
 		;	type_layout
+	% Options for internal use only
+	% (the values of these options are implied by the
+	% settings of other options)
 				% Stack layout information required to do
 				% a stack trace.
 		;	basic_stack_layout
@@ -160,8 +165,6 @@
 				% where typeinfos are live for any live data
 				% the includes that type variable.
 		;	typeinfo_liveness
-		;	highlevel_c
-		;	unboxed_float
 	% Code generation options
 		;	low_level_debug
 		;	trad_passes
@@ -1107,7 +1110,14 @@
 	inline_single_use	-	bool(yes),
 	inline_compound_threshold -	int(10),
 	common_struct		-	bool(yes),
+/****
+% XXX optimize_duplicate_calls is broken --
+% it doesn't take type information into account.
+% See tests/hard_coded/dupcall_types_bug.m.
+% We should re-enable the optimization only
+% when we have fixed that bug.
 	optimize_duplicate_calls -	bool(yes),
+****/
 	simple_neg		-	bool(yes)
 ]).
 
Index: tests/hard_coded/Mmakefile
===================================================================
RCS file: /home/mercury1/repository/tests/hard_coded/Mmakefile,v
retrieving revision 1.33
diff -u -r1.33 Mmakefile
--- Mmakefile	1998/06/12 07:05:43	1.33
+++ Mmakefile	1998/06/22 00:56:58
@@ -21,6 +21,7 @@
 	deep_copy_bug \
 	det_in_semidet_cntxt \
 	division_test \
+	dupcall_types_bug \
 	elim_special_pred \
 	eqv_type_bug \
 	error_func \
Index: tests/hard_coded/dupcall_types_bug.exp
===================================================================
RCS file: dupcall_types_bug.exp
diff -N dupcall_types_bug.exp
--- /dev/null	Mon Jun 22 11:00:50 1998
+++ dupcall_types_bug.exp	Mon Jun 22 11:00:31 1998
@@ -0,0 +1 @@
+Syntax error.
Index: tests/hard_coded/dupcall_types_bug.m
===================================================================
RCS file: dupcall_types_bug.m
diff -N dupcall_types_bug.m
--- /dev/null	Mon Jun 22 11:00:50 1998
+++ dupcall_types_bug.m	Mon Jun 22 10:58:54 1998
@@ -0,0 +1,26 @@
+% This is a regression test for a bug with duplicate call elimination
+% not taking types into account.
+
+:- module dupcall_types_bug.
+:- interface.
+:- import_module io.
+
+:- pred main(io__state::di, io__state::uo) is det.
+
+:- implementation.
+:- import_module string.
+
+main -->
+	{ FileName = "string",
+	  String = "1. ",
+	  string__length(String, Len),
+	  Posn0 = posn(1, 0, 0),
+	  read_from_string(FileName, String, Len, Int, Posn0, _),
+	  read_from_string(FileName, String, Len, Str, Posn0, _) },
+	( { Int = ok(I), Str = ok(S) } ->
+		io__write_int(I),
+		io__write_string(S),
+		io__nl
+	;
+		io__write_string("Syntax error.\n")
+	).

-- 
Fergus Henderson <fjh at cs.mu.oz.au>  |  "I have always known that the pursuit
WWW: <http://www.cs.mu.oz.au/~fjh>  |  of excellence is a lethal habit"
PGP: finger fjh at 128.250.37.3        |     -- the last words of T. S. Garp.