diff --git a/compiler/compile_target_code.m b/compiler/compile_target_code.m
index 81a3632d4..5decdb236 100644
--- a/compiler/compile_target_code.m
+++ b/compiler/compile_target_code.m
@@ -1,7 +1,7 @@
 %-----------------------------------------------------------------------------%
 % vim: ft=mercury ts=4 sw=4 et
 %-----------------------------------------------------------------------------%
-% Copyright (C) 2002-2005 The University of Melbourne.
+% Copyright (C) 2002-2006 The 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.
 %-----------------------------------------------------------------------------%
@@ -865,7 +865,7 @@ make_init_file(ErrorStream, MainModuleName, AllModules, Succeeded, !IO) :-
         io__close_output(InitFileStream, !IO),
         module_name_to_file_name(MainModuleName, ".init", yes, InitFileName,
             !IO),
-        update_interface(InitFileName, Succeeded1, !IO),
+        update_interface_return_succeeded(InitFileName, Succeeded1, !IO),
         Succeeded = Succeeded0 `and` Succeeded1
     ;
         InitFileRes = error(Error),
@@ -1071,7 +1071,7 @@ make_init_obj_file(ErrorStream, MustCompile, ModuleName, ModuleNames, Result,
     maybe_report_stats(Stats, !IO),
     (
         MkInitOK0 = yes,
-        update_interface(InitCFileName, MkInitOK1, !IO),
+        update_interface_return_succeeded(InitCFileName, MkInitOK1, !IO),
         (
             MkInitOK1 = yes,
             (
diff --git a/compiler/handle_options.m b/compiler/handle_options.m
index e74fbf0e9..3362fb26f 100644
--- a/compiler/handle_options.m
+++ b/compiler/handle_options.m
@@ -1707,7 +1707,25 @@ postprocess_options_lowlevel(!Globals) :-
     option_implies(optimize_frames, optimize_jumps, bool(yes), !Globals),
 
         % --optimize-proc-dups is implemented only with --trad-passes.
-    option_implies(optimize_proc_dups, trad_passes, bool(yes), !Globals).
+    option_implies(optimize_proc_dups, trad_passes, bool(yes), !Globals),
+
+    globals.lookup_bool_option(!.Globals, optimize_frames, OptFrames),
+    globals.lookup_bool_option(!.Globals, use_local_vars, OptLocalVars),
+    globals.lookup_int_option(!.Globals, optimize_repeat, OptRepeat),
+    (
+        ( OptFrames = yes
+        ; OptLocalVars = yes
+        ),
+        OptRepeat < 1
+    ->
+        % The frame optimization and the local vars optimization depend on
+        % the jump and label optimization having been done. They are turned
+        % on above, but they still won't be executed unless optimize_repeat
+        % is at least one.
+        globals__set_option(optimize_repeat, int(1), !Globals)
+    ;
+        true
+    ).
 
     % option_implies(SourceBoolOption, ImpliedOption, ImpliedOptionValue):
     % If the SourceBoolOption is set to yes, then the ImpliedOption is set
diff --git a/compiler/mercury_compile.m b/compiler/mercury_compile.m
index aef0f5880..f4b07a019 100644
--- a/compiler/mercury_compile.m
+++ b/compiler/mercury_compile.m
@@ -2735,7 +2735,7 @@ backend_pass_by_preds_4(PredInfo, !ProcInfo, ProcId, PredId, !HLDS,
     globals__lookup_bool_option(Globals, optimize, Optimize),
     (
         Optimize = yes,
-        optimize__proc(!.GlobalData, ProcCode0, ProcCode, !IO)
+        optimize_proc(!.GlobalData, ProcCode0, ProcCode, !IO)
     ;
         Optimize = no,
         ProcCode = ProcCode0
@@ -4041,7 +4041,7 @@ maybe_do_optimize(GlobalData, Verbose, Stats, !LLDS, !IO) :-
         Optimize = yes,
         maybe_write_string(Verbose, "% Doing optimizations...\n", !IO),
         maybe_flush_output(Verbose, !IO),
-        optimize_main(GlobalData, !LLDS, !IO),
+        optimize_procs(GlobalData, !LLDS, !IO),
         maybe_write_string(Verbose, "% done.\n", !IO),
         maybe_report_stats(Stats, !IO)
     ;
diff --git a/compiler/modules.m b/compiler/modules.m
index faecea7af..2759921ae 100644
--- a/compiler/modules.m
+++ b/compiler/modules.m
@@ -692,12 +692,13 @@
     %
 :- pred touch_datestamp(file_name::in, io::di, io::uo) is det.
 
-    % update_interface(FileName, Succeeded):
+    % update_interface_return_succeeded(FileName, Succeeded):
     %
     % Call the shell script mercury_update_interface to update the
     % interface file FileName if it has changed.
     %
-:- pred update_interface(file_name::in, bool::out, io::di, io::uo) is det.
+:- pred update_interface_return_succeeded(file_name::in, bool::out,
+    io::di, io::uo) is det.
 
 :- pred update_interface(file_name::in, io::di, io::uo) is det.
 
@@ -2242,7 +2243,7 @@ write_interface_file(_SourceFileName, ModuleName, Suffix, MaybeTimestamp,
         % update <Module>.int from <Module>.int.tmp if necessary
 
 update_interface(OutputFileName, !IO) :-
-    update_interface(OutputFileName, Succeeded, !IO),
+    update_interface_return_succeeded(OutputFileName, Succeeded, !IO),
     (
         Succeeded = no,
         report_error("problem updating interface files.", !IO)
@@ -2250,7 +2251,7 @@ update_interface(OutputFileName, !IO) :-
         Succeeded = yes
     ).
 
-update_interface(OutputFileName, Succeeded, !IO) :-
+update_interface_return_succeeded(OutputFileName, Succeeded, !IO) :-
     globals__io_lookup_bool_option(verbose, Verbose, !IO),
     maybe_write_string(Verbose, "% Updating interface:\n", !IO),
     TmpOutputFileName = OutputFileName ++ ".tmp",
diff --git a/compiler/optimize.m b/compiler/optimize.m
index 362f03e85..2b327d1c0 100644
--- a/compiler/optimize.m
+++ b/compiler/optimize.m
@@ -1,7 +1,7 @@
 %-----------------------------------------------------------------------------%
 % vim: ft=mercury ts=4 sw=4 et
 %-----------------------------------------------------------------------------%
-% Copyright (C) 1996-2005 The University of Melbourne.
+% Copyright (C) 1996-2006 The 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.
 %-----------------------------------------------------------------------------%
@@ -13,7 +13,7 @@
 
 %-----------------------------------------------------------------------------%
 
-:- module ll_backend__optimize.
+:- module ll_backend.optimize.
 :- interface.
 
 :- import_module ll_backend.global_data.
@@ -24,10 +24,10 @@
 
 %-----------------------------------------------------------------------------%
 
-:- pred optimize_main(global_data::in,
+:- pred optimize_procs(global_data::in,
     list(c_procedure)::in, list(c_procedure)::out, io::di, io::uo) is det.
 
-:- pred optimize__proc(global_data::in, c_procedure::in, c_procedure::out,
+:- pred optimize_proc(global_data::in, c_procedure::in, c_procedure::out,
     io::di, io::uo) is det.
 
 %-----------------------------------------------------------------------------%
@@ -71,35 +71,35 @@
 
 %-----------------------------------------------------------------------------%
 
-optimize_main(GlobalData, !Procs, !IO) :-
-    list__map_foldl(optimize__proc(GlobalData), !Procs, !IO).
+optimize_procs(GlobalData, !Procs, !IO) :-
+    list.map_foldl(optimize_proc(GlobalData), !Procs, !IO).
 
-optimize__proc(GlobalData, CProc0, CProc, !IO) :-
+optimize_proc(GlobalData, CProc0, CProc, !IO) :-
     some [!OptDebugInfo, !C, !Instrs] (
         CProc0 = c_procedure(Name, Arity, PredProcId, !:Instrs,
             ProcLabel, !:C, MayAlterRtti),
-        optimize__init_opt_debug_info(Name, Arity, PredProcId, ProcLabel,
+        init_opt_debug_info(Name, Arity, PredProcId, ProcLabel,
             !.Instrs, !.C, !:OptDebugInfo, !IO),
-        globals__io_lookup_int_option(optimize_repeat, Repeat, !IO),
+        globals.io_lookup_int_option(optimize_repeat, Repeat, !IO),
         (
             global_data_maybe_get_proc_layout(GlobalData,
                 PredProcId, ProcLayout)
         ->
             LabelMap = ProcLayout ^ internal_map,
-            map__sorted_keys(LabelMap, LayoutLabelNums),
-            LayoutLabels = list__map(make_internal_label(ProcLabel),
+            map.sorted_keys(LabelMap, LayoutLabelNums),
+            LayoutLabels = list.map(make_internal_label(ProcLabel),
                 LayoutLabelNums),
-            set__sorted_list_to_set(LayoutLabels, LayoutLabelSet)
+            set.sorted_list_to_set(LayoutLabels, LayoutLabelSet)
         ;
-            set__init(LayoutLabelSet)
+            set.init(LayoutLabelSet)
         ),
-        optimize__initial(LayoutLabelSet, ProcLabel, MayAlterRtti, !C,
+        optimize_initial(LayoutLabelSet, ProcLabel, MayAlterRtti, !C,
             !OptDebugInfo, !Instrs, !IO),
-        optimize__repeat(Repeat, LayoutLabelSet, ProcLabel, MayAlterRtti, !C,
+        optimize_repeat(Repeat, LayoutLabelSet, ProcLabel, MayAlterRtti, !C,
             !OptDebugInfo, !Instrs, !IO),
-        optimize__middle(yes, LayoutLabelSet, ProcLabel, MayAlterRtti, !C,
+        optimize_middle(yes, LayoutLabelSet, ProcLabel, MayAlterRtti, !C,
             !OptDebugInfo, !Instrs, !IO),
-        optimize__last(LayoutLabelSet, ProcLabel, !.C, !.OptDebugInfo, !Instrs,
+        optimize_last(LayoutLabelSet, ProcLabel, !.C, !.OptDebugInfo, !Instrs,
             !IO),
         CProc = c_procedure(Name, Arity, PredProcId, !.Instrs, ProcLabel,
             !.C, MayAlterRtti)
@@ -123,14 +123,14 @@ make_internal_label(ProcLabel, LabelNum) = internal(LabelNum, ProcLabel).
             )
     ;       no_opt_debug_info.
 
-:- pred optimize__init_opt_debug_info(string::in, int::in, pred_proc_id::in,
+:- pred init_opt_debug_info(string::in, int::in, pred_proc_id::in,
     proc_label::in, list(instruction)::in, counter::in, opt_debug_info::out,
     io::di, io::uo) is det.
 
-optimize__init_opt_debug_info(Name, Arity, PredProcId, ProcLabel, Instrs0,
-        Counter, OptDebugInfo, !IO) :-
-    globals__io_lookup_bool_option(debug_opt, DebugOpt, !IO),
-    globals__io_lookup_int_option(debug_opt_pred_id, DebugOptPredId, !IO),
+init_opt_debug_info(Name, Arity, PredProcId, ProcLabel, Instrs0, Counter,
+        OptDebugInfo, !IO) :-
+    globals.io_lookup_bool_option(debug_opt, DebugOpt, !IO),
+    globals.io_lookup_int_option(debug_opt_pred_id, DebugOptPredId, !IO),
     PredProcId = proc(PredId, ProcId),
     pred_id_to_int(PredId, PredIdInt),
     proc_id_to_int(ProcId, ProcIdInt),
@@ -144,21 +144,21 @@ optimize__init_opt_debug_info(Name, Arity, PredProcId, ProcLabel, Instrs0,
             ++ ".proc" ++ int_to_string(ProcIdInt),
         OptDebugInfo = opt_debug_info(BaseName, 0, 0, Instrs0),
 
-        io__call_system("mkdir -p " ++ opt_subdir_name, MkdirRes, !IO),
+        io.call_system("mkdir -p " ++ opt_subdir_name, MkdirRes, !IO),
         ( MkdirRes = ok(0) ->
             true
         ;
             unexpected(this_file, "cannot make " ++ opt_subdir_name)
         ),
         FileName = BaseName ++ ".opt0",
-        io__open_output(FileName, Res, !IO),
+        io.open_output(FileName, Res, !IO),
         ( Res = ok(FileStream) ->
-            io__set_output_stream(FileStream, OutputStream, !IO),
-            counter__allocate(NextLabel, Counter, _),
-            opt_debug__msg(yes, NextLabel, "before optimization", !IO),
-            opt_debug__maybe_dump_instrs(yes, ProcLabel, Instrs0, !IO),
-            io__set_output_stream(OutputStream, _, !IO),
-            io__close_output(FileStream, !IO)
+            io.set_output_stream(FileStream, OutputStream, !IO),
+            counter.allocate(NextLabel, Counter, _),
+            opt_debug.msg(yes, NextLabel, "before optimization", !IO),
+            opt_debug.maybe_dump_instrs(yes, ProcLabel, Instrs0, !IO),
+            io.set_output_stream(OutputStream, _, !IO),
+            io.close_output(FileStream, !IO)
         ;
             unexpected(this_file, "cannot open " ++ FileName)
         )
@@ -170,12 +170,11 @@ optimize__init_opt_debug_info(Name, Arity, PredProcId, ProcLabel, Instrs0,
 
 opt_subdir_name = "OptSubdir".
 
-:- pred optimize__maybe_opt_debug(list(instruction)::in, counter::in,
-    string::in, proc_label::in, opt_debug_info::in, opt_debug_info::out,
-    io::di, io::uo) is det.
+:- pred maybe_opt_debug(list(instruction)::in, counter::in, string::in,
+    proc_label::in, opt_debug_info::in, opt_debug_info::out, io::di, io::uo)
+    is det.
 
-optimize__maybe_opt_debug(Instrs, Counter, Msg, ProcLabel, !OptDebugInfo,
-        !IO) :-
+maybe_opt_debug(Instrs, Counter, Msg, ProcLabel, !OptDebugInfo, !IO) :-
     (
         !.OptDebugInfo = opt_debug_info(BaseName, OptNum0, PrevNum,
             PrevInstrs),
@@ -185,25 +184,25 @@ optimize__maybe_opt_debug(Instrs, Counter, Msg, ProcLabel, !OptDebugInfo,
             Same = no
         ),
         OptNum = OptNum0 + 1,
-        string__int_to_string(PrevNum, PrevNumStr),
-        string__int_to_string(OptNum, OptNumStr),
+        string.int_to_string(PrevNum, PrevNumStr),
+        string.int_to_string(OptNum, OptNumStr),
         PrevFileName = BaseName ++ ".opt" ++ PrevNumStr,
         OptFileName = BaseName ++ ".opt" ++ OptNumStr,
         DiffFileName = BaseName ++ ".diff" ++ OptNumStr,
-        io__open_output(OptFileName, Res, !IO),
+        io.open_output(OptFileName, Res, !IO),
         ( Res = ok(FileStream) ->
-            io__set_output_stream(FileStream, OutputStream, !IO),
-            counter__allocate(NextLabel, Counter, _),
-            opt_debug__msg(yes, NextLabel, Msg, !IO),
+            io.set_output_stream(FileStream, OutputStream, !IO),
+            counter.allocate(NextLabel, Counter, _),
+            opt_debug.msg(yes, NextLabel, Msg, !IO),
             (
                 Same = yes,
-                io__write_string("same as previous version\n", !IO)
+                io.write_string("same as previous version\n", !IO)
             ;
                 Same = no,
-                opt_debug__maybe_dump_instrs(yes, ProcLabel, Instrs, !IO)
+                opt_debug.maybe_dump_instrs(yes, ProcLabel, Instrs, !IO)
             ),
-            io__set_output_stream(OutputStream, _, !IO),
-            io__close_output(FileStream, !IO)
+            io.set_output_stream(OutputStream, _, !IO),
+            io.close_output(FileStream, !IO)
         ;
             ErrorMsg = "cannot open " ++ OptFileName,
             unexpected(this_file, ErrorMsg)
@@ -218,7 +217,7 @@ optimize__maybe_opt_debug(Instrs, Counter, Msg, ProcLabel, !OptDebugInfo,
             % of --debug-opt (zs) strongly prefers -u to -c.
             DiffCommand = "diff -u '" ++ PrevFileName ++ "' '" ++ OptFileName
                 ++ "' > '" ++ DiffFileName ++ "'",
-            io__call_system(DiffCommand, _, !IO),
+            io.call_system(DiffCommand, _, !IO),
             !:OptDebugInfo = opt_debug_info(BaseName, OptNum, OptNum, Instrs)
         )
     ;
@@ -227,29 +226,29 @@ optimize__maybe_opt_debug(Instrs, Counter, Msg, ProcLabel, !OptDebugInfo,
 
 %-----------------------------------------------------------------------------%
 
-:- pred optimize__initial(set(label)::in, proc_label::in, may_alter_rtti::in,
+:- pred optimize_initial(set(label)::in, proc_label::in, may_alter_rtti::in,
     counter::in, counter::out, opt_debug_info::in, opt_debug_info::out,
     list(instruction)::in, list(instruction)::out, io::di, io::uo) is det.
 
-optimize__initial(LayoutLabelSet, ProcLabel, MayAlterRtti, !C, !OptDebugInfo,
+optimize_initial(LayoutLabelSet, ProcLabel, MayAlterRtti, !C, !OptDebugInfo,
         !Instrs, !IO) :-
-    globals__io_lookup_bool_option(very_verbose, VeryVerbose, !IO),
-    LabelStr = opt_util__format_proc_label(ProcLabel),
+    globals.io_lookup_bool_option(very_verbose, VeryVerbose, !IO),
+    LabelStr = opt_util.format_proc_label(ProcLabel),
 
-    globals__io_lookup_bool_option(optimize_frames, FrameOpt, !IO),
+    globals.io_lookup_bool_option(optimize_frames, FrameOpt, !IO),
     (
         FrameOpt = yes,
         (
             VeryVerbose = yes,
-            io__write_string("% Optimizing nondet frames for ", !IO),
-            io__write_string(LabelStr, !IO),
-            io__write_string("\n", !IO)
+            io.write_string("% Optimizing nondet frames for ", !IO),
+            io.write_string(LabelStr, !IO),
+            io.write_string("\n", !IO)
         ;
             VeryVerbose = no
         ),
         frameopt_nondet(ProcLabel, LayoutLabelSet, MayAlterRtti, !C, !Instrs,
             _Mod),
-        optimize__maybe_opt_debug(!.Instrs, !.C, "after nondet frame opt",
+        maybe_opt_debug(!.Instrs, !.C, "after nondet frame opt",
             ProcLabel, !OptDebugInfo, !IO)
     ;
         FrameOpt = no
@@ -257,12 +256,12 @@ optimize__initial(LayoutLabelSet, ProcLabel, MayAlterRtti, !C, !OptDebugInfo,
 
 %-----------------------------------------------------------------------------%
 
-:- pred optimize__repeat(int::in, set(label)::in, proc_label::in,
+:- pred optimize_repeat(int::in, set(label)::in, proc_label::in,
     may_alter_rtti::in, counter::in, counter::out,
     opt_debug_info::in, opt_debug_info::out,
     list(instruction)::in, list(instruction)::out, io::di, io::uo) is det.
 
-optimize__repeat(CurIter, LayoutLabelSet, ProcLabel, MayAlterRtti,
+optimize_repeat(CurIter, LayoutLabelSet, ProcLabel, MayAlterRtti,
         !C, !OptDebugInfo, !Instrs, !IO) :-
     ( CurIter > 0 ->
         NextIter = CurIter - 1,
@@ -271,11 +270,11 @@ optimize__repeat(CurIter, LayoutLabelSet, ProcLabel, MayAlterRtti,
         ;
             Final = no
         ),
-        optimize__repeated(Final, LayoutLabelSet, ProcLabel, MayAlterRtti,
+        optimize_repeated(Final, LayoutLabelSet, ProcLabel, MayAlterRtti,
             !C, !OptDebugInfo, !Instrs, Mod, !IO),
         (
             Mod = yes,
-            optimize__repeat(NextIter, LayoutLabelSet, ProcLabel, MayAlterRtti,
+            optimize_repeat(NextIter, LayoutLabelSet, ProcLabel, MayAlterRtti,
                 !C, !OptDebugInfo, !Instrs, !IO)
         ;
             Mod = no
@@ -287,92 +286,92 @@ optimize__repeat(CurIter, LayoutLabelSet, ProcLabel, MayAlterRtti,
     % We short-circuit jump sequences before normal peepholing
     % to create more opportunities for use of the tailcall macro.
     %
-:- pred optimize__repeated(bool::in, set(label)::in, proc_label::in,
+:- pred optimize_repeated(bool::in, set(label)::in, proc_label::in,
     may_alter_rtti::in, counter::in, counter::out,
     opt_debug_info::in, opt_debug_info::out,
     list(instruction)::in, list(instruction)::out, bool::out,
     io::di, io::uo) is det.
 
-optimize__repeated(Final, LayoutLabelSet, ProcLabel, MayAlterRtti,
+optimize_repeated(Final, LayoutLabelSet, ProcLabel, MayAlterRtti,
         !C, !OptDebugInfo, !Instrs, Mod, !IO) :-
     InstrsAtStart = !.Instrs,
-    LabelStr = opt_util__format_proc_label(ProcLabel),
-    globals__io_lookup_bool_option(very_verbose, VeryVerbose, !IO),
-    globals__io_lookup_bool_option(optimize_jumps, Jumpopt, !IO),
-    globals__io_lookup_bool_option(optimize_fulljumps, FullJumpopt, !IO),
-    globals__io_lookup_bool_option(pessimize_tailcalls,
+    LabelStr = opt_util.format_proc_label(ProcLabel),
+    globals.io_lookup_bool_option(very_verbose, VeryVerbose, !IO),
+    globals.io_lookup_bool_option(optimize_jumps, Jumpopt, !IO),
+    globals.io_lookup_bool_option(optimize_fulljumps, FullJumpopt, !IO),
+    globals.io_lookup_bool_option(pessimize_tailcalls,
         PessimizeTailCalls, !IO),
-    globals__io_lookup_bool_option(checked_nondet_tailcalls,
+    globals.io_lookup_bool_option(checked_nondet_tailcalls,
         CheckedNondetTailCalls, !IO),
     (
         Jumpopt = yes,
         (
             VeryVerbose = yes,
-            io__write_string("% Optimizing jumps for ", !IO),
-            io__write_string(LabelStr, !IO),
-            io__write_string("\n", !IO)
+            io.write_string("% Optimizing jumps for ", !IO),
+            io.write_string(LabelStr, !IO),
+            io.write_string("\n", !IO)
         ;
             VeryVerbose = no
         ),
         jumpopt_main(LayoutLabelSet, MayAlterRtti, ProcLabel, FullJumpopt,
             Final, PessimizeTailCalls, CheckedNondetTailCalls, !C, !Instrs,
             Mod1),
-        optimize__maybe_opt_debug(!.Instrs, !.C, "after jump opt",
+        maybe_opt_debug(!.Instrs, !.C, "after jump opt",
             ProcLabel, !OptDebugInfo, !IO)
     ;
         Jumpopt = no,
         Mod1 = no
     ),
-    globals__io_lookup_bool_option(optimize_peep, Peephole, !IO),
+    globals.io_lookup_bool_option(optimize_peep, Peephole, !IO),
     (
         Peephole = yes,
         (
             VeryVerbose = yes,
-            io__write_string("% Optimizing locally for ", !IO),
-            io__write_string(LabelStr, !IO),
-            io__write_string("\n", !IO)
+            io.write_string("% Optimizing locally for ", !IO),
+            io.write_string(LabelStr, !IO),
+            io.write_string("\n", !IO)
         ;
             VeryVerbose = no
         ),
-        globals__io_get_gc_method(GC_Method, !IO),
-        peephole__optimize(GC_Method, !Instrs, Mod2),
-        optimize__maybe_opt_debug(!.Instrs, !.C, "after peephole",
+        globals.io_get_gc_method(GC_Method, !IO),
+        peephole.optimize(GC_Method, !Instrs, Mod2),
+        maybe_opt_debug(!.Instrs, !.C, "after peephole",
             ProcLabel, !OptDebugInfo, !IO)
     ;
         Peephole = no,
         Mod2 = no
     ),
-    globals__io_lookup_bool_option(optimize_labels, LabelElim, !IO),
+    globals.io_lookup_bool_option(optimize_labels, LabelElim, !IO),
     (
         LabelElim = yes,
         (
             VeryVerbose = yes,
-            io__write_string("% Optimizing labels for ", !IO),
-            io__write_string(LabelStr, !IO),
-            io__write_string("\n", !IO)
+            io.write_string("% Optimizing labels for ", !IO),
+            io.write_string(LabelStr, !IO),
+            io.write_string("\n", !IO)
         ;
             VeryVerbose = no
         ),
         labelopt_main(Final, LayoutLabelSet, !Instrs, Mod3),
-        optimize__maybe_opt_debug(!.Instrs, !.C, "after label opt",
+        maybe_opt_debug(!.Instrs, !.C, "after label opt",
             ProcLabel, !OptDebugInfo, !IO)
     ;
         LabelElim = no,
         Mod3 = no
     ),
-    globals__io_lookup_bool_option(optimize_dups, DupElim, !IO),
+    globals.io_lookup_bool_option(optimize_dups, DupElim, !IO),
     (
         DupElim = yes,
         (
             VeryVerbose = yes,
-            io__write_string("% Optimizing duplicates for ", !IO),
-            io__write_string(LabelStr, !IO),
-            io__write_string("\n", !IO)
+            io.write_string("% Optimizing duplicates for ", !IO),
+            io.write_string(LabelStr, !IO),
+            io.write_string("\n", !IO)
         ;
             VeryVerbose = no
         ),
         dupelim_main(ProcLabel, !C, !Instrs),
-        optimize__maybe_opt_debug(!.Instrs, !.C, "after duplicates",
+        maybe_opt_debug(!.Instrs, !.C, "after duplicates",
             ProcLabel, !OptDebugInfo, !IO)
     ;
         DupElim = no
@@ -382,38 +381,38 @@ optimize__repeated(Final, LayoutLabelSet, ProcLabel, MayAlterRtti,
     ;
         Mod = yes
     ),
-    globals__io_lookup_bool_option(detailed_statistics, Statistics, !IO),
+    globals.io_lookup_bool_option(detailed_statistics, Statistics, !IO),
     maybe_report_stats(Statistics, !IO).
 
-:- pred optimize__middle(bool::in, set(label)::in, proc_label::in,
+:- pred optimize_middle(bool::in, set(label)::in, proc_label::in,
     may_alter_rtti::in, counter::in, counter::out,
     opt_debug_info::in, opt_debug_info::out,
     list(instruction)::in, list(instruction)::out, io::di, io::uo) is det.
 
-optimize__middle(Final, LayoutLabelSet, ProcLabel, MayAlterRtti, !C,
+optimize_middle(Final, LayoutLabelSet, ProcLabel, MayAlterRtti, !C,
         !OptDebugInfo, !Instrs, !IO) :-
-    globals__io_lookup_bool_option(very_verbose, VeryVerbose, !IO),
-    LabelStr = opt_util__format_proc_label(ProcLabel),
+    globals.io_lookup_bool_option(very_verbose, VeryVerbose, !IO),
+    LabelStr = opt_util.format_proc_label(ProcLabel),
 
-    globals__io_lookup_bool_option(optimize_frames, FrameOpt, !IO),
+    globals.io_lookup_bool_option(optimize_frames, FrameOpt, !IO),
     (
         FrameOpt = yes,
         (
             VeryVerbose = yes,
-            io__write_string("% Optimizing frames for ", !IO),
-            io__write_string(LabelStr, !IO),
-            io__write_string("\n", !IO)
+            io.write_string("% Optimizing frames for ", !IO),
+            io.write_string(LabelStr, !IO),
+            io.write_string("\n", !IO)
         ;
             VeryVerbose = no
         ),
-        globals__io_get_globals(Globals, !IO),
+        globals.io_get_globals(Globals, !IO),
         frameopt_main(ProcLabel, !C, !Instrs, Globals, Mod1),
-        optimize__maybe_opt_debug(!.Instrs, !.C, "after frame opt",
+        maybe_opt_debug(!.Instrs, !.C, "after frame opt",
             ProcLabel, !OptDebugInfo, !IO),
-        globals__io_lookup_bool_option(optimize_fulljumps, FullJumpopt, !IO),
-        globals__io_lookup_bool_option(pessimize_tailcalls,
+        globals.io_lookup_bool_option(optimize_fulljumps, FullJumpopt, !IO),
+        globals.io_lookup_bool_option(pessimize_tailcalls,
             PessimizeTailCalls, !IO),
-        globals__io_lookup_bool_option(checked_nondet_tailcalls,
+        globals.io_lookup_bool_option(checked_nondet_tailcalls,
             CheckedNondetTailCalls, !IO),
         (
             ( FullJumpopt = yes
@@ -422,16 +421,16 @@ optimize__middle(Final, LayoutLabelSet, ProcLabel, MayAlterRtti, !C,
         ->
             (
                 VeryVerbose = yes,
-                io__write_string("% Optimizing jumps for ", !IO),
-                io__write_string(LabelStr, !IO),
-                io__write_string("\n", !IO)
+                io.write_string("% Optimizing jumps for ", !IO),
+                io.write_string(LabelStr, !IO),
+                io.write_string("\n", !IO)
             ;
                 VeryVerbose = no
             ),
             jumpopt_main(LayoutLabelSet, MayAlterRtti, ProcLabel, FullJumpopt,
                 Final, PessimizeTailCalls, CheckedNondetTailCalls, !C, !Instrs,
                 _Mod2),
-            optimize__maybe_opt_debug(!.Instrs, !.C, "after jumps",
+            maybe_opt_debug(!.Instrs, !.C, "after jumps",
                 ProcLabel, !OptDebugInfo, !IO)
         ;
             true
@@ -440,14 +439,14 @@ optimize__middle(Final, LayoutLabelSet, ProcLabel, MayAlterRtti, !C,
             Mod1 = yes,
             (
                 VeryVerbose = yes,
-                io__write_string("% Optimizing labels for ", !IO),
-                io__write_string(LabelStr, !IO),
-                io__write_string("\n", !IO)
+                io.write_string("% Optimizing labels for ", !IO),
+                io.write_string(LabelStr, !IO),
+                io.write_string("\n", !IO)
             ;
                 VeryVerbose = no
             ),
             labelopt_main(Final, LayoutLabelSet, !Instrs, _Mod3),
-            optimize__maybe_opt_debug(!.Instrs, !.C, "after labels",
+            maybe_opt_debug(!.Instrs, !.C, "after labels",
                 ProcLabel, !OptDebugInfo, !IO)
         ;
             Mod1 = no
@@ -455,40 +454,40 @@ optimize__middle(Final, LayoutLabelSet, ProcLabel, MayAlterRtti, !C,
     ;
         FrameOpt = no
     ),
-    globals__io_lookup_bool_option(use_local_vars, UseLocalVars, !IO),
+    globals.io_lookup_bool_option(use_local_vars, UseLocalVars, !IO),
     (
         UseLocalVars = yes,
         (
             VeryVerbose = yes,
-            io__write_string("% Optimizing local vars for ", !IO),
-            io__write_string(LabelStr, !IO),
-            io__write_string("\n", !IO)
+            io.write_string("% Optimizing local vars for ", !IO),
+            io.write_string(LabelStr, !IO),
+            io.write_string("\n", !IO)
         ;
             VeryVerbose = no
         ),
-        globals__io_lookup_int_option(num_real_r_regs, NumRealRRegs, !IO),
-        globals__io_lookup_int_option(local_var_access_threshold,
+        globals.io_lookup_int_option(num_real_r_regs, NumRealRRegs, !IO),
+        globals.io_lookup_int_option(local_var_access_threshold,
             AccessThreshold, !IO),
-        globals__io_lookup_bool_option(auto_comments, AutoComments, !IO),
-        use_local_vars__main(!Instrs, NumRealRRegs, AccessThreshold,
+        globals.io_lookup_bool_option(auto_comments, AutoComments, !IO),
+        use_local_vars_proc(!Instrs, NumRealRRegs, AccessThreshold,
             AutoComments, ProcLabel, !C),
-        optimize__maybe_opt_debug(!.Instrs, !.C, "after use_local_vars",
+        maybe_opt_debug(!.Instrs, !.C, "after use_local_vars",
             ProcLabel, !OptDebugInfo, !IO)
     ;
         UseLocalVars = no
     ).
 
-:- pred optimize__last(set(label)::in, proc_label::in, counter::in,
+:- pred optimize_last(set(label)::in, proc_label::in, counter::in,
     opt_debug_info::in, list(instruction)::in, list(instruction)::out,
     io::di, io::uo) is det.
 
-optimize__last(LayoutLabelSet, ProcLabel, C, !.OptDebugInfo, !Instrs, !IO) :-
-    globals__io_lookup_bool_option(very_verbose, VeryVerbose, !IO),
-    LabelStr = opt_util__format_proc_label(ProcLabel),
+optimize_last(LayoutLabelSet, ProcLabel, C, !.OptDebugInfo, !Instrs, !IO) :-
+    globals.io_lookup_bool_option(very_verbose, VeryVerbose, !IO),
+    LabelStr = opt_util.format_proc_label(ProcLabel),
 
-    globals__io_lookup_bool_option(optimize_reassign, Reassign, !IO),
-    globals__io_lookup_bool_option(optimize_delay_slot, DelaySlot, !IO),
-    globals__io_lookup_bool_option(use_local_vars, UseLocalVars, !IO),
+    globals.io_lookup_bool_option(optimize_reassign, Reassign, !IO),
+    globals.io_lookup_bool_option(optimize_delay_slot, DelaySlot, !IO),
+    globals.io_lookup_bool_option(use_local_vars, UseLocalVars, !IO),
     (
         ( Reassign = yes
         ; DelaySlot = yes
@@ -499,14 +498,14 @@ optimize__last(LayoutLabelSet, ProcLabel, C, !.OptDebugInfo, !Instrs, !IO) :-
         % since they can confuse reassign, wrap_blocks and delay_slot.
         (
             VeryVerbose = yes,
-            io__write_string("% Optimizing labels for ", !IO),
-            io__write_string(LabelStr, !IO),
-            io__write_string("\n", !IO)
+            io.write_string("% Optimizing labels for ", !IO),
+            io.write_string(LabelStr, !IO),
+            io.write_string("\n", !IO)
         ;
             VeryVerbose = no
         ),
         labelopt_main(no, LayoutLabelSet, !Instrs, _Mod1),
-        optimize__maybe_opt_debug(!.Instrs, C, "after label opt",
+        maybe_opt_debug(!.Instrs, C, "after label opt",
             ProcLabel, !OptDebugInfo, !IO)
     ;
         true
@@ -515,14 +514,14 @@ optimize__last(LayoutLabelSet, ProcLabel, C, !.OptDebugInfo, !Instrs, !IO) :-
         Reassign = yes,
         (
             VeryVerbose = yes,
-            io__write_string("% Optimizing reassign for ", !IO),
-            io__write_string(LabelStr, !IO),
-            io__write_string("\n", !IO)
+            io.write_string("% Optimizing reassign for ", !IO),
+            io.write_string(LabelStr, !IO),
+            io.write_string("\n", !IO)
         ;
             VeryVerbose = no
         ),
         remove_reassign(!Instrs),
-        optimize__maybe_opt_debug(!.Instrs, C, "after reassign",
+        maybe_opt_debug(!.Instrs, C, "after reassign",
             ProcLabel, !OptDebugInfo, !IO)
     ;
         Reassign = no
@@ -531,41 +530,41 @@ optimize__last(LayoutLabelSet, ProcLabel, C, !.OptDebugInfo, !Instrs, !IO) :-
         DelaySlot = yes,
         (
             VeryVerbose = yes,
-            io__write_string("% Optimizing delay slot for ", !IO),
-            io__write_string(LabelStr, !IO),
-            io__write_string("\n", !IO)
+            io.write_string("% Optimizing delay slot for ", !IO),
+            io.write_string(LabelStr, !IO),
+            io.write_string("\n", !IO)
         ;
             VeryVerbose = no
         ),
         fill_branch_delay_slot(!Instrs),
-        optimize__maybe_opt_debug(!.Instrs, C, "after delay slots",
+        maybe_opt_debug(!.Instrs, C, "after delay slots",
             ProcLabel, !OptDebugInfo, !IO)
     ;
         DelaySlot = no
     ),
     (
         VeryVerbose = yes,
-        io__write_string("% Optimizing returns for ", !IO),
-        io__write_string(LabelStr, !IO),
-        io__write_string("\n", !IO)
+        io.write_string("% Optimizing returns for ", !IO),
+        io.write_string(LabelStr, !IO),
+        io.write_string("\n", !IO)
     ;
         VeryVerbose = no
     ),
     combine_decr_sp(!Instrs),
-    optimize__maybe_opt_debug(!.Instrs, C, "after combine decr_sp",
+    maybe_opt_debug(!.Instrs, C, "after combine decr_sp",
         ProcLabel, !OptDebugInfo, !IO),
     (
         UseLocalVars = yes,
         (
             VeryVerbose = yes,
-            io__write_string("% Wrapping blocks for ", !IO),
-            io__write_string(LabelStr, !IO),
-            io__write_string("\n", !IO)
+            io.write_string("% Wrapping blocks for ", !IO),
+            io.write_string(LabelStr, !IO),
+            io.write_string("\n", !IO)
         ;
             VeryVerbose = no
         ),
         wrap_blocks(!Instrs),
-        optimize__maybe_opt_debug(!.Instrs, C, "after wrap blocks",
+        maybe_opt_debug(!.Instrs, C, "after wrap blocks",
             ProcLabel, !.OptDebugInfo, _OptDebugInfo, !IO)
     ;
         UseLocalVars = no
@@ -579,12 +578,12 @@ optimize__last(LayoutLabelSet, ProcLabel, C, !.OptDebugInfo, !Instrs, !IO) :-
 :- func mangle_name_as_filename(string) = string.
 
 mangle_name_as_filename(Str0) = Str :-
-    string__foldl(escape_dir_char, Str0, "", Str).
+    string.foldl(escape_dir_char, Str0, "", Str).
 
 :- pred escape_dir_char(char::in, string::in, string::out) is det.
 
 escape_dir_char(Char, !Str) :-
-    ( dir__is_directory_separator(Char) ->
+    ( dir.is_directory_separator(Char) ->
         !:Str = !.Str ++ "_slash_"
     ;
         !:Str = !.Str ++ char_to_string(Char)
diff --git a/compiler/use_local_vars.m b/compiler/use_local_vars.m
index 34c1bac85..a897ceb4f 100644
--- a/compiler/use_local_vars.m
+++ b/compiler/use_local_vars.m
@@ -1,7 +1,7 @@
 %-----------------------------------------------------------------------------%
 % vim: ft=mercury ts=4 sw=4 et
 %-----------------------------------------------------------------------------%
-% Copyright (C) 2001-2005 The University of Melbourne.
+% Copyright (C) 2001-2006 The 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.
 %-----------------------------------------------------------------------------%
@@ -58,7 +58,7 @@
 
 %-----------------------------------------------------------------------------%
 
-:- module ll_backend__use_local_vars.
+:- module ll_backend.use_local_vars.
 :- interface.
 
 :- import_module ll_backend.llds.
@@ -70,7 +70,7 @@
 
 %-----------------------------------------------------------------------------%
 
-:- pred use_local_vars__main(list(instruction)::in, list(instruction)::out,
+:- pred use_local_vars_proc(list(instruction)::in, list(instruction)::out,
     int::in, int::in, bool::in, proc_label::in, counter::in, counter::out)
     is det.
 
@@ -96,12 +96,12 @@
 %-----------------------------------------------------------------------------%
 %-----------------------------------------------------------------------------%
 
-use_local_vars__main(Instrs0, Instrs, NumRealRRegs, AccessThreshold,
+use_local_vars_proc(Instrs0, Instrs, NumRealRRegs, AccessThreshold,
         AutoComments, ProcLabel, !C) :-
     create_basic_blocks(Instrs0, Comments0, ProcLabel, !C, NewLabels,
         LabelSeq, BlockMap0),
     flatten_basic_blocks(LabelSeq, BlockMap0, TentativeInstrs),
-    livemap__build(TentativeInstrs, MaybeLiveMap),
+    livemap.build(TentativeInstrs, MaybeLiveMap),
     (
         % Instrs0 must have contained C code which cannot be analyzed
         MaybeLiveMap = no,
@@ -110,7 +110,7 @@ use_local_vars__main(Instrs0, Instrs, NumRealRRegs, AccessThreshold,
         MaybeLiveMap = yes(LiveMap),
         extend_basic_blocks(LabelSeq, EBBLabelSeq, BlockMap0, EBBBlockMap0,
             NewLabels),
-        list__foldl(use_local_vars_block(LiveMap, NumRealRRegs,
+        list.foldl(use_local_vars_block(LiveMap, NumRealRRegs,
             AccessThreshold), EBBLabelSeq, EBBBlockMap0, EBBBlockMap),
         flatten_basic_blocks(EBBLabelSeq, EBBBlockMap, Instrs1),
         (
@@ -129,10 +129,10 @@ use_local_vars__main(Instrs0, Instrs, NumRealRRegs, AccessThreshold,
 
 use_local_vars_block(LiveMap, NumRealRRegs, AccessThreshold, Label,
         !BlockMap) :-
-    map__lookup(!.BlockMap, Label, BlockInfo0),
+    map.lookup(!.BlockMap, Label, BlockInfo0),
     BlockInfo0 = block_info(BlockLabel, LabelInstr, RestInstrs0,
         FallInto, JumpLabels, MaybeFallThrough),
-    counter__init(1, TempCounter0),
+    counter.init(1, TempCounter0),
     use_local_vars_instrs(RestInstrs0, RestInstrs, TempCounter0, TempCounter,
         NumRealRRegs, AccessThreshold, LiveMap, MaybeFallThrough),
     ( TempCounter = TempCounter0 ->
@@ -140,7 +140,7 @@ use_local_vars_block(LiveMap, NumRealRRegs, AccessThreshold, Label,
     ;
         BlockInfo = block_info(BlockLabel, LabelInstr, RestInstrs, FallInto,
             JumpLabels, MaybeFallThrough),
-        map__det_update(!.BlockMap, Label, BlockInfo, !:BlockMap)
+        map.det_update(!.BlockMap, Label, BlockInfo, !:BlockMap)
     ).
 
 %-----------------------------------------------------------------------------%
@@ -155,7 +155,7 @@ use_local_vars_instrs(!RestInstrs, !TempCounter,
         MaybeFallThrough),
     ( AccessThreshold >= 1 ->
         opt_access(!RestInstrs, !TempCounter, NumRealRRegs,
-            set__init, AccessThreshold)
+            set.init, AccessThreshold)
     ;
         true
     ).
@@ -180,19 +180,19 @@ opt_assign([Instr0 | TailInstrs0], Instrs, !TempCounter, NumRealRRegs,
             find_compulsory_lvals(TailInstrs0, LiveMap, MaybeFallThrough,
                 no, MaybeCompulsoryLvals),
             MaybeCompulsoryLvals = known(CompulsoryLvals),
-            not set__member(ToLval, CompulsoryLvals)
+            not set.member(ToLval, CompulsoryLvals)
         ->
-            counter__allocate(TempNum, !TempCounter),
+            counter.allocate(TempNum, !TempCounter),
             NewLval = temp(r, TempNum),
             substitute_lval_in_defn(ToLval, NewLval, Instr0, Instr),
-            list__map_foldl(
-                exprn_aux__substitute_lval_in_instr(ToLval, NewLval),
+            list.map_foldl(
+                exprn_aux.substitute_lval_in_instr(ToLval, NewLval),
                 TailInstrs0, TailInstrs1, 0, _),
             opt_assign(TailInstrs1, TailInstrs, !TempCounter, NumRealRRegs,
                 LiveMap, MaybeFallThrough),
             Instrs = [Instr | TailInstrs]
         ;
-            counter__allocate(TempNum, !TempCounter),
+            counter.allocate(TempNum, !TempCounter),
             NewLval = temp(r, TempNum),
             substitute_lval_in_instr_until_defn(ToLval, NewLval,
                 TailInstrs0, TailInstrs1, 0, NumSubst),
@@ -227,7 +227,7 @@ find_compulsory_lvals([], LiveMap, MaybeFallThrough, _PrevLivevals,
         MaybeCompulsoryLvals) :-
     (
         MaybeFallThrough = yes(FallThrough),
-        map__lookup(LiveMap, FallThrough, CompulsoryLvals),
+        map.lookup(LiveMap, FallThrough, CompulsoryLvals),
         MaybeCompulsoryLvals = known(CompulsoryLvals)
     ;
         MaybeFallThrough = no,
@@ -249,14 +249,14 @@ find_compulsory_lvals([Instr | Instrs], LiveMap, MaybeFallThrough,
             this_file, "find_compulsory_lvals: call without livevals"),
         % The livevals instruction will include all the live lvals
         % in MaybeCompulsoryLvals after we return.
-        !:MaybeCompulsoryLvals = known(set__init)
+        !:MaybeCompulsoryLvals = known(set.init)
     ;
         Uinstr = goto(_Target),
         PrevLivevals = yes
     ->
         % The livevals instruction will include all the live lvals
         % in MaybeCompulsoryLvals after we return.
-        !:MaybeCompulsoryLvals = known(set__init)
+        !:MaybeCompulsoryLvals = known(set.init)
     ;
         possible_targets(Uinstr, Labels, NonLabelCodeAddrs),
         (
@@ -268,8 +268,8 @@ find_compulsory_lvals([Instr | Instrs], LiveMap, MaybeFallThrough,
                     no, !:MaybeCompulsoryLvals)
             ;
                 Labels = [_ | _],
-                list__map(map__lookup(LiveMap), Labels, LabelsLiveLvals),
-                AllLabelsLiveLvals = set__union_list(LabelsLiveLvals),
+                list.map(map.lookup(LiveMap), Labels, LabelsLiveLvals),
+                AllLabelsLiveLvals = set.union_list(LabelsLiveLvals),
                 find_compulsory_lvals(Instrs, LiveMap, MaybeFallThrough,
                     no, !:MaybeCompulsoryLvals),
                 union_maybe_compulsory_lvals(AllLabelsLiveLvals,
@@ -287,7 +287,7 @@ find_compulsory_lvals([Instr | Instrs], LiveMap, MaybeFallThrough,
 union_maybe_compulsory_lvals(New, !MaybeCompulsoryLvals) :-
     (
         !.MaybeCompulsoryLvals = known(OldCompulsoryLvals),
-        set__union(New, OldCompulsoryLvals, AllCompulsoryLvals),
+        set.union(New, OldCompulsoryLvals, AllCompulsoryLvals),
         !:MaybeCompulsoryLvals = known(AllCompulsoryLvals)
     ;
         !.MaybeCompulsoryLvals = unknown_must_assume_all
@@ -306,21 +306,21 @@ opt_access([Instr0 | TailInstrs0], Instrs, !TempCounter, NumRealRRegs,
         Uinstr0 = assign(ToLval, FromRval),
         lvals_in_lval(ToLval, ToSubLvals),
         lvals_in_rval(FromRval, FromSubLvals),
-        list__append(ToSubLvals, FromSubLvals, SubLvals),
-        list__filter(
+        list.append(ToSubLvals, FromSubLvals, SubLvals),
+        list.filter(
             base_lval_worth_replacing_not_tried(AlreadyTried0, NumRealRRegs),
             SubLvals, ReplaceableSubLvals),
         ReplaceableSubLvals = [ChosenLval | ChooseableRvals]
     ->
         OrigTempCounter = !.TempCounter,
-        counter__allocate(TempNum, !TempCounter),
+        counter.allocate(TempNum, !TempCounter),
         TempLval = temp(r, TempNum),
         lvals_in_lval(ChosenLval, SubChosenLvals),
         expect(unify(SubChosenLvals, []),
             this_file, "opt_access: nonempty SubChosenLvals"),
         substitute_lval_in_instr_until_defn(ChosenLval, TempLval,
             [Instr0 | TailInstrs0], Instrs1, 0, NumReplacements),
-        set__insert(AlreadyTried0, ChosenLval, AlreadyTried1),
+        set.insert(AlreadyTried0, ChosenLval, AlreadyTried1),
         ( NumReplacements >= AccessThreshold ->
             TempAssign = assign(TempLval, lval(ChosenLval))
                 - "factor out common sub lval",
@@ -334,12 +334,12 @@ opt_access([Instr0 | TailInstrs0], Instrs, !TempCounter, NumRealRRegs,
         ;
             !:TempCounter = OrigTempCounter,
             opt_access(TailInstrs0, TailInstrs, !TempCounter, NumRealRRegs,
-                set__init, AccessThreshold),
+                set.init, AccessThreshold),
             Instrs = [Instr0 | TailInstrs]
         )
     ;
         opt_access(TailInstrs0, TailInstrs, !TempCounter, NumRealRRegs,
-            set__init, AccessThreshold),
+            set.init, AccessThreshold),
         Instrs = [Instr0 | TailInstrs]
     ).
 
@@ -361,7 +361,7 @@ base_lval_worth_replacing(NumRealRRegs, Lval) :-
     is semidet.
 
 base_lval_worth_replacing_not_tried(AlreadyTried, NumRealRRegs, Lval) :-
-    \+ set__member(Lval, AlreadyTried),
+    \+ set.member(Lval, AlreadyTried),
     base_lval_worth_replacing(NumRealRRegs, Lval).
 
 %-----------------------------------------------------------------------------%
@@ -460,7 +460,7 @@ substitute_lval_in_instr_until_defn_2(OldLval, NewLval, !Instr, !Instrs, !N) :-
             % contains is itself.
             true
         ;
-            exprn_aux__substitute_lval_in_instr(OldLval, NewLval, !Instr, !N),
+            exprn_aux.substitute_lval_in_instr(OldLval, NewLval, !Instr, !N),
             substitute_lval_in_instr_until_defn(OldLval, NewLval, !Instrs, !N)
         )
     ;
@@ -473,10 +473,10 @@ substitute_lval_in_instr_until_defn_2(OldLval, NewLval, !Instr, !Instrs, !N) :-
         Uinstr0 = goto(_)
     ;
         Uinstr0 = computed_goto(_, _),
-        exprn_aux__substitute_lval_in_instr(OldLval, NewLval, !Instr, !N)
+        exprn_aux.substitute_lval_in_instr(OldLval, NewLval, !Instr, !N)
     ;
         Uinstr0 = if_val(_, _),
-        exprn_aux__substitute_lval_in_instr(OldLval, NewLval, !Instr, !N)
+        exprn_aux.substitute_lval_in_instr(OldLval, NewLval, !Instr, !N)
     ;
         Uinstr0 = save_maxfr(_)
     ;
@@ -489,7 +489,7 @@ substitute_lval_in_instr_until_defn_2(OldLval, NewLval, !Instr, !Instrs, !N) :-
             % contains is itself.
             true
         ;
-            exprn_aux__substitute_lval_in_instr(OldLval, NewLval, !Instr, !N),
+            exprn_aux.substitute_lval_in_instr(OldLval, NewLval, !Instr, !N),
             substitute_lval_in_instr_until_defn(OldLval, NewLval, !Instrs, !N)
         )
     ;
diff --git a/tests/valid/Mmakefile b/tests/valid/Mmakefile
index fd2c39846..e040dbcec 100644
--- a/tests/valid/Mmakefile
+++ b/tests/valid/Mmakefile
@@ -87,6 +87,7 @@ OTHER_PROGS= \
 	empty_bound_inst_list \
 	empty_switch \
 	error \
+	eval \
 	existential_cons \
 	explicit_quant \
 	export_before_func \
diff --git a/tests/valid/eval.m b/tests/valid/eval.m
new file mode 100644
index 000000000..20cdc558c
--- /dev/null
+++ b/tests/valid/eval.m
@@ -0,0 +1,66 @@
+% This is a regression test. The compiler on 29 January, 2006 aborted with
+% the message "Software Error: basic_block.m: Unexpected: extend_basic_blocks:
+% fall through mismatch" when invoked with -O0 --optimize-repeat=0
+% --optimize-saved-vars on this file.
+%
+% The contents of this file are an extract from eval.m in the CVS directory
+% benchmarks/progs/icfp2000.
+
+:- module eval.
+:- interface.
+
+:- import_module bool.
+:- import_module list.
+:- import_module io.
+
+:- type token_list == list(token_group).
+
+:- type token_group
+	--->    single_token(token)
+	;       function(token_list)
+	;       array(token_list).
+
+:- type token
+	--->    identifier(string)
+	;       binder(string)
+	;       boolean(bool)
+	;       number(int)
+	;       string(string).
+
+:- type code == token_list.
+
+:- pred interpret(code::in, io__state::di, io__state::uo) is det.
+
+%-----------------------------------------------------------------------------%
+
+:- implementation.
+
+:- import_module map.
+:- import_module array.
+
+:- type value
+	--->	boolean(bool)
+	;	int(int)
+	;	real(float)
+	;	string(string).
+
+:- type id == string.
+
+:- type env == map(id, value).
+
+:- type stack == list(value).
+
+interpret(Code) -->
+	initial_setup(Env0, Stack0),
+	interpret(Code, Env0, Stack0, _Env, _Stack).
+
+:- pred initial_setup(env::out, stack::out,
+	io__state::di, io__state::uo) is det.
+
+initial_setup(Env, []) -->
+	{ map__init(Env) }.
+
+:- pred interpret(code::in, env::in, stack::in,
+	env::out, stack::out, io__state::di, io__state::uo) is det.
+
+interpret(_, Env, Stack, Env, Stack) --> [].