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mercury/compiler/jumpopt.m
Zoltan Somogyi c643291d1f Add cons_list and snoc_list to cord.m. 
library/cord.m:
    Add those two new predicates.

NEWS.md:
    Announce the additions.

compiler/*.m:
    Use snoc_list in many places.

tests/hard_coded/test_cord_2.{m,exp}:
    Extend this test case to test cons_list.
2025-10-10 18:48:26 +11:00

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%-----------------------------------------------------------------------------%
% vim: ft=mercury ts=4 sw=4 et
%-----------------------------------------------------------------------------%
% Copyright (C) 1994-2007, 2009-2012 The University of Melbourne.
% Copyright (C) 2013, 2015-2020, 2024-2025 The Mercury team.
% This file may only be copied under the terms of the GNU General
% Public License - see the file COPYING in the Mercury distribution.
%-----------------------------------------------------------------------------%
%
% File: jumpopt.m.
% Author: zs.
%
% This module contains code that optimizes jumps to jumps.
%
%-----------------------------------------------------------------------------%
:- module ll_backend.jumpopt.
:- interface.
:- import_module libs.
:- import_module libs.optimization_options.
:- import_module ll_backend.llds.
:- import_module mdbcomp.
:- import_module mdbcomp.prim_data.
:- import_module bool.
:- import_module counter.
:- import_module list.
:- import_module set_tree234.
%-----------------------------------------------------------------------------%
% optimize_jumps_in_proc(LayoutLabels, MayAlterRtti, ProcLabel,
% Fulljumpopt, Recjump, PessimizeTailCalls, CheckedNondetTailCall,
% !LabelNumCounter, !Instrs, Mod):
%
% Take an instruction list and optimize jumps. This includes the jumps
% implicit in procedure returns.
%
% LayoutLabels gives the set of labels that have layout structures.
% This module will not optimize jumps to labels in this set, since
% this may interfere with the RTTI recorded for these labels.
% MayAlterRtti says whether we are allowed to perform optimizations
% that may interfere with RTTI.
%
% Fulljumpopt should be the value of the --optimize-fulljumps option.
%
% Recjump should be an indication of whether this is the final
% application of this optimization.
%
% PessimizeTailCalls should be the value of the --pessimize-tailcalls
% option.
%
% CheckedNondetTailCall should be the value of the
% --checked-nondet-tailcalls option.
%
% Mod will say whether the instruction sequence was modified
% by the optimization.
%
:- pred optimize_jumps_in_proc(set_tree234(label)::in, may_alter_rtti::in,
proc_label::in, maybe_opt_fulljumps::in, bool::in,
maybe_pessimize_llds_tailcalls::in, maybe_opt_checked_nondet_tailcalls::in,
counter::in, counter::out, list(instruction)::in, list(instruction)::out,
bool::out) is det.
%-----------------------------------------------------------------------------%
%-----------------------------------------------------------------------------%
:- implementation.
:- import_module backend_libs.
:- import_module backend_libs.builtin_ops.
:- import_module hlds.
:- import_module hlds.hlds_data.
:- import_module hlds.hlds_llds.
:- import_module ll_backend.code_util.
:- import_module ll_backend.opt_util.
:- import_module parse_tree.
:- import_module parse_tree.prog_data.
:- import_module parse_tree.prog_data_foreign.
:- import_module cord.
:- import_module map.
:- import_module maybe.
:- import_module require.
:- import_module string.
%-----------------------------------------------------------------------------%
% We first build up a bunch of tables giving information about labels.
% We then traverse the instruction list, using the information in the
% tables to short-circuit jumps.
%
% InstrMap: Maps each label to the next real (non-comment, non-livevals)
% instruction after that label.
% LvalMap: Maps each label to yes(Livevals) if the label is followed
% by a livevals instruction, and to no otherwise.
% BlockMap: Maps each label to the block following that label.
% This includes all instructions up to the first one that
% cannot fall through.
% ProcMap: Maps each label that begins a det epilog to the epilog.
% SuccMap: Maps each label that begins a nondet epilog to the epilog.
% SdprocMap: Maps each label that begins a semidet epilog to the epilog.
% This can be the success epilog or the failure epilog.
% ForkMap: Maps each label that begins a full semidet epilog (code to
% test r1, and to execute the success or failure epilog
% depending on the result) to the epilog.
%
% BlockMap will not contain the initial block of the procedure unless
% Recjump is set. The intention is that Recjump will not be set until
% frameopt, which can do a better job of optimizing this block, have
% been applied.
optimize_jumps_in_proc(LayoutLabels, MayAlterRtti, ProcLabel, Fulljumpopt,
Recjump, PessimizeTailCalls, CheckedNondetTailCall, !LabelNumCounter,
!Instrs, Mod) :-
some [!InstrMap, !BlockMap, !LvalMap, !ProcMap, !SdprocMap, !SuccMap,
!ForkMap]
(
Instrs0 = !.Instrs,
map.init(!:InstrMap),
map.init(!:BlockMap),
map.init(!:LvalMap),
map.init(!:ProcMap),
map.init(!:SdprocMap),
map.init(!:SuccMap),
jump_opt_build_maps(!.Instrs, Recjump, !InstrMap, !BlockMap, !LvalMap,
!ProcMap, !SdprocMap, !SuccMap),
jump_opt_build_forkmap(!.Instrs, !.SdprocMap, map.init, !:ForkMap),
(
PessimizeTailCalls = do_not_pessimize_llds_tailcalls
;
PessimizeTailCalls = pessimize_llds_tailcalls,
!:ProcMap = map.init,
!:SdprocMap = map.init,
!:SuccMap = map.init,
!:ForkMap = map.init
),
JumpOptInfo = jump_opt_info(!.InstrMap, !.BlockMap, !.LvalMap,
!.ProcMap, !.SdprocMap, !.ForkMap, !.SuccMap, LayoutLabels,
Fulljumpopt, MayAlterRtti),
(
CheckedNondetTailCall = opt_checked_nondet_tailcalls,
CheckedNondetTailCallInfo0 =
check_nondet_tailcalls(ProcLabel, !.LabelNumCounter),
jump_opt_instr_list(!.Instrs, comment(""), JumpOptInfo,
CheckedNondetTailCallInfo0, CheckedNondetTailCallInfo,
cord.init, InstrsCord),
(
CheckedNondetTailCallInfo =
check_nondet_tailcalls(_, !:LabelNumCounter)
;
CheckedNondetTailCallInfo = do_not_check_nondet_tailcalls,
unexpected($pred, "lost the next label number")
)
;
CheckedNondetTailCall = do_not_opt_checked_nondet_tailcalls,
CheckedNondetTailCallInfo0 = do_not_check_nondet_tailcalls,
jump_opt_instr_list(!.Instrs, comment(""), JumpOptInfo,
CheckedNondetTailCallInfo0, _, cord.init, InstrsCord)
),
!:Instrs = cord.list(InstrsCord),
opt_util.filter_out_bad_livevals(!Instrs),
( if !.Instrs = Instrs0 then
Mod = no
else
Mod = yes
)
).
%-----------------------------------------------------------------------------%
:- pred jump_opt_build_maps(list(instruction)::in, bool::in,
instrmap::in, instrmap::out, tailmap::in, tailmap::out,
lvalmap::in, lvalmap::out, tailmap::in, tailmap::out,
tailmap::in, tailmap::out, tailmap::in, tailmap::out) is det.
jump_opt_build_maps([], _, !InstrMap, !BlockMap,
!LvalMap, !ProcMap, !SdprocMap, !SuccMap).
jump_opt_build_maps([Instr0 | Instrs0], Recjump, !InstrMap, !BlockMap,
!LvalMap, !ProcMap, !SdprocMap, !SuccMap) :-
Instr0 = llds_instr(Uinstr0, Comment0),
( if Uinstr0 = label(Label) then
opt_util.skip_comments(Instrs0, Instrs1),
( if Instrs1 = [Instr1 | _], Instr1 = llds_instr(livevals(_), _) then
map.det_insert(Label, yes(Instr1), !LvalMap)
else
map.det_insert(Label, no, !LvalMap)
),
opt_util.skip_comments_livevals(Instrs1, Instrs2),
( if Instrs2 = [Instr2 | _] then
map.det_insert(Label, Instr2, !InstrMap)
else
true
),
( if opt_util.is_proceed_next(Instrs1, Between1) then
map.det_insert(Label, Between1, !ProcMap)
else
true
),
( if opt_util.is_sdproceed_next(Instrs1, Between2) then
map.det_insert(Label, Between2, !SdprocMap)
else
true
),
( if opt_util.is_succeed_next(Instrs1, Between3) then
map.det_insert(Label, Between3, !SuccMap)
else
true
),
% Put the start of the procedure into Blockmap only after
% frameopt has had a shot at it.
( if
(
Label = internal_label(_, _),
% We put entry labels into !BlockMap only if the comment
% does NOT end with "nofulljump".
not string.suffix(Comment0, "nofulljump")
;
Label = entry_label(_, _),
% We put entry labels into !BlockMap only if Recjump = yes.
Recjump = yes
)
then
opt_util.find_no_fallthrough(Instrs1, Block),
map.det_insert(Label, Block, !BlockMap)
else
true
)
else
true
),
jump_opt_build_maps(Instrs0, Recjump, !InstrMap, !BlockMap, !LvalMap,
!ProcMap, !SdprocMap, !SuccMap).
% Find labels followed by a test of r1 where both paths set r1 to
% its original value and proceed.
%
:- pred jump_opt_build_forkmap(list(instruction)::in, tailmap::in,
tailmap::in, tailmap::out) is det.
jump_opt_build_forkmap([], _SdprocMap, !ForkMap).
jump_opt_build_forkmap([llds_instr(Uinstr, _Comment) | Instrs], SdprocMap,
!ForkMap) :-
( if
Uinstr = label(Label),
opt_util.is_forkproceed_next(Instrs, SdprocMap, Between)
then
map.det_insert(Label, Between, !ForkMap)
else
true
),
jump_opt_build_forkmap(Instrs, SdprocMap, !ForkMap).
%-----------------------------------------------------------------------------%
:- type jump_opt_info
---> jump_opt_info(
joi_instr_map :: instrmap,
joi_block_map :: tailmap,
joi_lval_map :: lvalmap,
joi_proc_map :: tailmap,
joi_sdproc_map :: tailmap,
joi_fork_map :: tailmap,
joi_succ_map :: tailmap,
joi_layout_labels :: set_tree234(label),
joi_full_jump_opt :: maybe_opt_fulljumps,
joi_may_alter_rtti :: may_alter_rtti
).
:- type new_remain
---> nr_specified(
new_instructions :: list(instruction),
remaining_instructions :: list(instruction)
)
; nr_usual_case.
% The list of new instructions contains just Instr0, and
% the list of remaining instructions, on which to recurse,
% Instrs0.
:- type maybe_check_nondet_tailcalls
---> do_not_check_nondet_tailcalls
; check_nondet_tailcalls(proc_label, counter).
% Optimize the given instruction list by eliminating unnecessary jumps.
%
% We handle calls by attempting to turn them into tailcalls. If this fails,
% we try to short-circuit the return address.
%
% We handle gotos by first trying to eliminate them. If this fails,
% we check whether their target label begins a proceed/succeed sequence;
% if it does, we replace the label by that sequence. If this fails as well,
% we check whether the instruction at the ultimate target label can
% fall through. If it cannot (e.g. call), we replace the goto with
% this instruction.
%
% We handle computed gotos by attempting to short-circuit all the labels
% in the label list.
%
% We handle if-vals by trying to turn them into the assignment
% of a boolean value to r1, or by short-circuiting the target label.
% We also try to eliminate a goto following an if-val, if we can do so
% by negating the condition and possibly also deleting a label between
% the if-val and the goto.
%
% We build up the generated instruction list in reverse order, because
% building it in right order would make instr_list not tail recursive,
% and thus unable to handle very long instruction lists.
%
:- pred jump_opt_instr_list(list(instruction)::in, instr::in,
jump_opt_info::in,
maybe_check_nondet_tailcalls::in, maybe_check_nondet_tailcalls::out,
cord(instruction)::in, cord(instruction)::out) is det.
jump_opt_instr_list([], _PrevInstr, _,
!CheckedNondetTailCallInfo, !InstrsCord).
jump_opt_instr_list([Instr0 | Instrs0], PrevInstr, JumpOptInfo,
!CheckedNondetTailCallInfo, !InstrsCord) :-
Instr0 = llds_instr(Uinstr0, Comment0),
% We do a switch on the instruction type to ensure that we short circuit
% all the labels that are in InstrMap but not in LayoutLabels in *all*
% instructions in which they occur. This means we must fully search
% every part of every instruction that may possibly hold a label.
% In theory, this means every lval and every rval, but in practice we
% know that rvals representing e.g. the tags of fields cannot contain
% labels.
(
Uinstr0 = llcall(_, _, _, _, _, _),
jump_opt_llcall(Uinstr0, Comment0, Instrs0, PrevInstr, JumpOptInfo,
!CheckedNondetTailCallInfo, NewRemain)
;
Uinstr0 = goto(_),
jump_opt_goto(Uinstr0, Comment0, Instrs0, PrevInstr, JumpOptInfo,
!CheckedNondetTailCallInfo, NewRemain)
;
Uinstr0 = computed_goto(IndexRval, MaybeMaxIndex, MaybeTargets0),
InstrMap = JumpOptInfo ^ joi_instr_map,
% Short-circuit all the destination labels.
short_circuit_maybe_labels(InstrMap, MaybeTargets0, MaybeTargets),
( if MaybeTargets = MaybeTargets0 then
NewRemain = nr_usual_case
else
Shorted = Comment0 ++ " (some shortcircuits)",
NewInstrs = [llds_instr(computed_goto(IndexRval,
MaybeMaxIndex, MaybeTargets), Shorted)],
NewRemain = nr_specified(NewInstrs, Instrs0)
)
;
Uinstr0 = if_val(_, _),
jump_opt_if_val(Uinstr0, Comment0, Instrs0, PrevInstr, JumpOptInfo,
NewRemain)
;
Uinstr0 = assign(Lval, Rval0),
% Any labels mentioned in Rval0 should be short-circuited.
InstrMap = JumpOptInfo ^ joi_instr_map,
short_circuit_labels_rval(InstrMap, Rval0, Rval),
( if Rval = Rval0 then
NewRemain = nr_usual_case
else
Shorted = Comment0 ++ " (some shortcircuits)",
NewInstrs = [llds_instr(assign(Lval, Rval), Shorted)],
NewRemain = nr_specified(NewInstrs, Instrs0)
)
;
Uinstr0 = keep_assign(Lval, Rval0),
% Any labels mentioned in Rval0 should be short-circuited.
InstrMap = JumpOptInfo ^ joi_instr_map,
short_circuit_labels_rval(InstrMap, Rval0, Rval),
( if Rval = Rval0 then
NewRemain = nr_usual_case
else
Shorted = Comment0 ++ " (some shortcircuits)",
NewInstrs = [llds_instr(keep_assign(Lval, Rval), Shorted)],
NewRemain = nr_specified(NewInstrs, Instrs0)
)
;
Uinstr0 = mkframe(FrameInfo, Redoip),
( if Redoip = yes(code_label(Label0)) then
InstrMap = JumpOptInfo ^ joi_instr_map,
short_circuit_label(InstrMap, Label0, Label),
( if Label = Label0 then
NewRemain = nr_usual_case
else
Shorted = Comment0 ++ " (some shortcircuits)",
NewInstrs =
[llds_instr(mkframe(FrameInfo, yes(code_label(Label))),
Shorted)],
NewRemain = nr_specified(NewInstrs, Instrs0)
)
else
NewRemain = nr_usual_case
)
;
Uinstr0 = foreign_proc_code(_, _, _, _, _, _, _, _, _, _),
jump_opt_foreign_proc_code(Uinstr0, Comment0, Instrs0, PrevInstr,
JumpOptInfo, NewRemain)
;
Uinstr0 = block(_, _, _),
% These are supposed to be introduced only after jumpopt is run
% for the last time.
unexpected($pred, "block")
;
Uinstr0 = fork_new_child(SyncTerm, Child0),
InstrMap = JumpOptInfo ^ joi_instr_map,
short_circuit_label(InstrMap, Child0, Child),
( if Child = Child0 then
NewRemain = nr_usual_case
else
Uinstr = fork_new_child(SyncTerm, Child),
Comment = Comment0 ++ " (redirect)",
Instr = llds_instr(Uinstr, Comment),
NewRemain = nr_specified([Instr], Instrs0)
)
;
Uinstr0 = join_and_continue(SyncTerm, Label0),
InstrMap = JumpOptInfo ^ joi_instr_map,
short_circuit_label(InstrMap, Label0, Label),
( if Label = Label0 then
NewRemain = nr_usual_case
else
Uinstr = join_and_continue(SyncTerm, Label),
Comment = Comment0 ++ " (redirect)",
Instr = llds_instr(Uinstr, Comment),
NewRemain = nr_specified([Instr], Instrs0)
)
;
Uinstr0 = lc_wait_free_slot(_, _, _),
% The label in the third argument should not be referred to
% from any code in the procedure's LLDS instruction sequence,
% so there is no way for it to be short circuited.
NewRemain = nr_usual_case
;
Uinstr0 = lc_spawn_off(LCRval, LCSRval, Child0),
InstrMap = JumpOptInfo ^ joi_instr_map,
short_circuit_label(InstrMap, Child0, Child),
( if Child = Child0 then
NewRemain = nr_usual_case
else
Uinstr = lc_spawn_off(LCRval, LCSRval, Child),
Comment = Comment0 ++ " (redirect)",
Instr = llds_instr(Uinstr, Comment),
NewRemain = nr_specified([Instr], Instrs0)
)
;
( Uinstr0 = arbitrary_c_code(_, _, _)
; Uinstr0 = comment(_)
; Uinstr0 = livevals(_)
; Uinstr0 = label(_)
; Uinstr0 = save_maxfr(_)
; Uinstr0 = restore_maxfr(_)
; Uinstr0 = incr_sp(_, _, _)
; Uinstr0 = decr_sp(_)
; Uinstr0 = decr_sp_and_return(_)
; Uinstr0 = push_region_frame(_, _)
; Uinstr0 = region_fill_frame(_, _, _, _, _)
; Uinstr0 = region_set_fixed_slot(_, _, _)
; Uinstr0 = use_and_maybe_pop_region_frame(_, _)
; Uinstr0 = store_ticket(_)
; Uinstr0 = reset_ticket(_, _)
; Uinstr0 = discard_ticket
; Uinstr0 = prune_ticket
; Uinstr0 = prune_tickets_to(_)
; Uinstr0 = mark_ticket_stack(_)
; Uinstr0 = mark_hp(_)
; Uinstr0 = free_heap(_)
; Uinstr0 = incr_hp(_, _, _, _, _, _, _, _)
; Uinstr0 = restore_hp(_)
; Uinstr0 = init_sync_term(_, _, _)
; Uinstr0 = lc_create_loop_control(_, _)
; Uinstr0 = lc_join_and_terminate(_, _)
),
NewRemain = nr_usual_case
),
(
NewRemain = nr_usual_case,
ReplacementInstrsEmpty = no,
RecurseInstrs = Instrs0,
cord.snoc(Instr0, !InstrsCord)
;
NewRemain = nr_specified(ReplacementInstrs, RecurseInstrs),
cord.snoc_list(ReplacementInstrs, !InstrsCord),
(
ReplacementInstrs = [],
ReplacementInstrsEmpty = yes
;
ReplacementInstrs = [_ | _],
ReplacementInstrsEmpty = no
)
),
( if
( Uinstr0 = comment(_)
; ReplacementInstrsEmpty = yes
)
then
NewPrevInstr = PrevInstr
else
NewPrevInstr = Uinstr0
),
jump_opt_instr_list(RecurseInstrs, NewPrevInstr, JumpOptInfo,
!CheckedNondetTailCallInfo, !InstrsCord).
:- pred jump_opt_llcall(instr::in(instr_llcall), string::in,
list(instruction)::in, instr::in, jump_opt_info::in,
maybe_check_nondet_tailcalls::in, maybe_check_nondet_tailcalls::out,
new_remain::out) is det.
jump_opt_llcall(Uinstr0, Comment0, Instrs0, PrevInstr, JumpOptInfo,
!CheckedNondetTailCallInfo, NewRemain) :-
Uinstr0 = llcall(Proc, RetAddr, LiveInfos, Context, GoalPath, CallModel),
( if RetAddr = code_label(RetLabel) then
( if
(
JumpOptInfo ^ joi_may_alter_rtti = must_not_alter_rtti
;
LayoutLabels = JumpOptInfo ^ joi_layout_labels,
set_tree234.member(RetLabel, LayoutLabels)
)
then
% We cannot optimize the call. Test for this once, here, instead
% of at the end of each of the following conditions.
NewRemain = nr_usual_case
else if
% Look for det style tailcalls. We look for this even if
% the call is semidet, because one of the optimizations below
% turns a pair of semidet epilogs into a det epilog.
( CallModel = call_model_det(allow_lco)
; CallModel = call_model_semidet(allow_lco)
),
ProcMap = JumpOptInfo ^ joi_proc_map,
map.search(ProcMap, RetLabel, Between0),
PrevInstr = livevals(Livevals)
then
opt_util.filter_out_livevals(Between0, Between1),
NewInstrs = Between1 ++
[llds_instr(livevals(Livevals), ""),
llds_instr(goto(Proc), redirect_comment(Comment0))],
NewRemain = nr_specified(NewInstrs, Instrs0)
else if
% Look for semidet style tailcalls.
CallModel = call_model_semidet(allow_lco),
ForkMap = JumpOptInfo ^ joi_fork_map,
map.search(ForkMap, RetLabel, Between),
PrevInstr = livevals(Livevals)
then
NewInstrs = Between ++
[llds_instr(livevals(Livevals), ""),
llds_instr(goto(Proc), redirect_comment(Comment0))],
NewRemain = nr_specified(NewInstrs, Instrs0)
else if
% Look for nondet style tailcalls which do not need
% a runtime check.
CallModel = call_model_nondet(unchecked_tail_call),
SuccMap = JumpOptInfo ^ joi_succ_map,
map.search(SuccMap, RetLabel, BetweenIncl),
BetweenIncl = [llds_instr(livevals(_), _), llds_instr(goto(_), _)],
PrevInstr = livevals(Livevals)
then
NewInstrs = [
llds_instr(assign(maxfr, lval(prevfr_slot(lval(curfr)))),
"discard this frame"),
llds_instr(assign(succip, lval(succip_slot(lval(curfr)))),
"setup PC on return from tailcall"),
llds_instr(assign(curfr, lval(succfr_slot(lval(curfr)))),
"setup curfr on return from tailcall"),
llds_instr(livevals(Livevals), ""),
llds_instr(goto(Proc), redirect_comment(Comment0))
],
NewRemain = nr_specified(NewInstrs, Instrs0)
else if
% Look for nondet style tailcalls which do need
% a runtime check.
CallModel = call_model_nondet(checked_tail_call),
!.CheckedNondetTailCallInfo =
check_nondet_tailcalls(ProcLabel, LabelNumCounter0),
SuccMap = JumpOptInfo ^ joi_succ_map,
map.search(SuccMap, RetLabel, BetweenIncl),
BetweenIncl = [llds_instr(livevals(_), _), llds_instr(goto(_), _)],
PrevInstr = livevals(Livevals)
then
counter.allocate(LabelNum, LabelNumCounter0, LabelNumCounter1),
NewLabel = internal_label(LabelNum, ProcLabel),
NewInstrs = [
llds_instr(if_val(binop(
int_cmp(int_type_int, ne), lval(curfr), lval(maxfr)),
code_label(NewLabel)),
"branch around if cannot tail call"),
llds_instr(assign(maxfr, lval(prevfr_slot(lval(curfr)))),
"discard this frame"),
llds_instr(assign(succip, lval(succip_slot(lval(curfr)))),
"setup PC on return from tailcall"),
llds_instr(assign(curfr, lval(succfr_slot(lval(curfr)))),
"setup curfr on return from tailcall"),
llds_instr(livevals(Livevals), ""),
llds_instr(goto(Proc), redirect_comment(Comment0)),
llds_instr(label(NewLabel), "non tail call"),
llds_instr(livevals(Livevals), ""),
llds_instr(Uinstr0, Comment0)
],
NewRemain = nr_specified(NewInstrs, Instrs0),
!:CheckedNondetTailCallInfo =
check_nondet_tailcalls(ProcLabel, LabelNumCounter1)
else if
% Short circuit the return label if possible.
InstrMap = JumpOptInfo ^ joi_instr_map,
map.search(InstrMap, RetLabel, RetInstr)
then
final_dest(InstrMap, RetLabel, DestLabel, RetInstr, _DestInstr),
( if RetLabel = DestLabel then
NewInstrs = [llds_instr(Uinstr0, Comment0)]
else
NewInstrs = [llds_instr(llcall(Proc, code_label(DestLabel),
LiveInfos, Context, GoalPath, CallModel),
redirect_comment(Comment0))]
),
NewRemain = nr_specified(NewInstrs, Instrs0)
else
NewRemain = nr_usual_case
)
else
NewRemain = nr_usual_case
).
:- pred jump_opt_goto(instr::in(instr_goto), string::in,
list(instruction)::in, instr::in, jump_opt_info::in,
maybe_check_nondet_tailcalls::in, maybe_check_nondet_tailcalls::out,
new_remain::out) is det.
jump_opt_goto(Uinstr0, Comment0, Instrs0, PrevInstr, JumpOptInfo,
!CheckedNondetTailCallInfo, NewRemain) :-
Uinstr0 = goto(TargetAddr),
( if TargetAddr = code_label(TargetLabel) then
( if
% Eliminate the goto if possible.
opt_util.is_this_label_next(TargetLabel, Instrs0, _)
then
NewInstrs = [],
NewRemain = nr_specified(NewInstrs, Instrs0)
else if
PrevInstr = if_val(_, code_label(IfTargetLabel)),
opt_util.is_this_label_next(IfTargetLabel, Instrs0, _)
then
% Eliminating the goto (by the local peephole pass)
% is better than shortcircuiting it here,
% PROVIDED the test will succeed most of the time;
% we could use profiling feedback on this.
% We cannot eliminate the instruction here because
% that would require altering the if_val instruction.
NewInstrs = [llds_instr(Uinstr0, Comment0)],
NewRemain = nr_specified(NewInstrs, Instrs0)
else if
% Replace a jump to a det epilog with the epilog.
ProcMap = JumpOptInfo ^ joi_proc_map,
map.search(ProcMap, TargetLabel, Between0)
then
adjust_livevals(PrevInstr, Between0, Between),
NewInstrs = Between ++
[llds_instr(goto(code_succip), "shortcircuit")],
NewRemain = nr_specified(NewInstrs, Instrs0)
else if
% Replace a jump to a semidet epilog with the epilog.
SdprocMap = JumpOptInfo ^ joi_sdproc_map,
map.search(SdprocMap, TargetLabel, Between0)
then
adjust_livevals(PrevInstr, Between0, Between),
NewInstrs = Between ++
[llds_instr(goto(code_succip), "shortcircuit")],
NewRemain = nr_specified(NewInstrs, Instrs0)
else if
% Replace a jump to a nondet epilog with the epilog.
SuccMap = JumpOptInfo ^ joi_succ_map,
map.search(SuccMap, TargetLabel, BetweenIncl0)
then
adjust_livevals(PrevInstr, BetweenIncl0, NewInstrs),
NewRemain = nr_specified(NewInstrs, Instrs0)
else if
% Replace a jump to a non-epilog block with the block itself.
% These jumps are treated separately from jumps to epilog blocks,
% for two reasons. First, epilog blocks are always short, so we
% always want to replace jumps to them, whereas other blocks
% may be long, so we want to replace jumps to them only if the
% fulljumps option was given. Second, non-epilog blocks may contain
% branches to other labels in this procedure, and we want to
% make sure that these are short-circuited. This short-circuiting
% is necessary because another optimization below eliminates
% labels, which is correct only if jumps to those labels are
% short-circuited everywhere.
JumpOptInfo ^ joi_full_jump_opt = opt_fulljumps,
InstrMap = JumpOptInfo ^ joi_instr_map,
map.search(InstrMap, TargetLabel, TargetInstr),
final_dest(InstrMap, TargetLabel, DestLabel,
TargetInstr, _DestInstr),
BlockMap = JumpOptInfo ^ joi_block_map,
map.search(BlockMap, DestLabel, Block),
block_may_be_duplicated(Block) = yes
then
opt_util.filter_out_labels(Block, FilteredBlock),
adjust_livevals(PrevInstr, FilteredBlock, AdjustedBlock),
% Block may end with a goto to DestLabel. We avoid infinite
% expansion in such cases by removing DestLabel from BlockMap,
% though only while processing AdjustedBlock.
map.delete(DestLabel, BlockMap, CrippledBlockMap),
CrippledJumpOptInfo = JumpOptInfo ^ joi_block_map :=
CrippledBlockMap,
jump_opt_instr_list(AdjustedBlock, comment(""),
CrippledJumpOptInfo, !CheckedNondetTailCallInfo,
cord.init, NewInstrsCord),
NewRemain = nr_specified(cord.list(NewInstrsCord), Instrs0)
else if
% Short-circuit the goto.
InstrMap = JumpOptInfo ^ joi_instr_map,
map.search(InstrMap, TargetLabel, TargetInstr)
then
final_dest(InstrMap, TargetLabel, DestLabel,
TargetInstr, DestInstr),
DestInstr = llds_instr(UdestInstr, _Destcomment),
Shorted = "shortcircuited jump: " ++ Comment0,
opt_util.can_instr_fall_through(UdestInstr) = Canfallthrough,
(
Canfallthrough = no,
NewInstrs0 = [llds_instr(UdestInstr, Shorted)]
;
Canfallthrough = yes,
( if TargetLabel = DestLabel then
NewInstrs0 = [llds_instr(Uinstr0, Comment0)]
else
NewInstrs0 =
[llds_instr(goto(code_label(DestLabel)), Shorted)]
)
),
LvalMap = JumpOptInfo ^ joi_lval_map,
( if map.search(LvalMap, DestLabel, yes(Lvalinstr)) then
adjust_livevals(PrevInstr, [Lvalinstr | NewInstrs0], NewInstrs)
else
NewInstrs = NewInstrs0
),
NewRemain = nr_specified(NewInstrs, Instrs0)
else
NewRemain = nr_usual_case
)
else
NewRemain = nr_usual_case
).
:- pred jump_opt_if_val(instr::in(instr_if_val), string::in,
list(instruction)::in, instr::in, jump_opt_info::in,
new_remain::out) is det.
jump_opt_if_val(Uinstr0, Comment0, Instrs0, _PrevInstr, JumpOptInfo,
NewRemain) :-
Uinstr0 = if_val(Cond, TargetAddr),
( if TargetAddr = code_label(TargetLabel) then
JumpOptInfo = jump_opt_info(InstrMap, BlockMap, _LvalMap,
_ProcMap, _SdprocMap, _ForkMap, _SuccMap, LayoutLabels,
Fulljumpopt, _MayAlterRtti),
( if
% Attempt to transform code such as
%
% if (Cond) L2
% L1:
% goto L3
% L2: ...
%
% into
%
% if (! Cond) L3
% L2: ...
%
% The label L1 may be present or not. If it is present, we are
% eliminating it, which is possible only because we short-circuit
% all jumps to it (make them jump directly to L3). This may not be
% possible if L3 is a non-label code address; e.g. we cannot jump
% to non-label code addresses from computed gotos.
opt_util.skip_comments(Instrs0, Instrs1),
Instrs1 = [Instr1 | Instrs2],
( if Instr1 = llds_instr(label(ElimLabel), _) then
not set_tree234.member(ElimLabel, LayoutLabels),
opt_util.skip_comments(Instrs2, Instrs3),
Instrs3 = [GotoInstr | AfterGoto],
HaveLabel = yes
else
Instr1 = GotoInstr,
AfterGoto = Instrs2,
HaveLabel = no
),
GotoInstr = llds_instr(goto(GotoTarget), GotoComment),
( HaveLabel = no ; GotoTarget = code_label(_) ),
opt_util.skip_comments(AfterGoto, AfterGotoComments),
AfterGotoComments = [LabelInstr | _],
LabelInstr = llds_instr(label(TargetLabel), _)
then
code_util.negate_rval(Cond, NotCond),
NewInstr = llds_instr(if_val(NotCond, GotoTarget), GotoComment),
NewInstrs = [],
% The transformed code may fit the pattern again, so make sure that
% we look for the pattern again by giving all of the transformed
% instructions to the recursive call. We can't go into an infinite
% loop because each application of the transformation strictly
% reduces the size of the code.
RemainInstrs = [NewInstr | AfterGoto],
NewRemain = nr_specified(NewInstrs, RemainInstrs)
else if
% Attempt to transform code such as
%
% if (Cond) L1
% goto L2
%
% into
%
% if (! Cond) L2
% <code at L1>
%
% when we know the code at L1 and don't know the code at L2.
% Here, we just generate
%
% if (! Cond) L2
% goto L1
%
% and get the code processed again starting after the if_val,
% to get the recursive call to replace the goto to L1
% with the code at L1.
Fulljumpopt = opt_fulljumps,
map.search(BlockMap, TargetLabel, _TargetBlock),
opt_util.skip_comments(Instrs0, Instrs1),
Instrs1 = [GotoInstr | AfterGoto],
GotoInstr = llds_instr(goto(GotoAddr), GotoComment),
not (
GotoAddr = code_label(GotoLabel),
map.search(BlockMap, GotoLabel, _)
)
then
code_util.negate_rval(Cond, NotCond),
NewIfInstr = llds_instr(if_val(NotCond, GotoAddr), GotoComment),
NewInstrs = [NewIfInstr],
NewGotoComment = Comment0 ++ " (switched)",
NewGotoInstr =
llds_instr(goto(code_label(TargetLabel)), NewGotoComment),
RemainInstrs = [NewGotoInstr | AfterGoto],
NewRemain = nr_specified(NewInstrs, RemainInstrs)
else if
map.search(InstrMap, TargetLabel, TargetInstr)
then
final_dest(InstrMap, TargetLabel, DestLabel,
TargetInstr, _DestInstr),
( if
% Attempt to transform code such as
%
% if (Cond) L1
% r1 = MR_FALSE (or MR_TRUE)
% when followed by
% <epilog>
% ...
% L1:
% r1 = MR_TRUE (or MR_FALSE)
% <epilog>
%
% into
%
% r1 = Cond (or r1 = !Cond)
% <epilog>
%
opt_util.is_sdproceed_next(Instrs0, BetweenFT),
map.search(BlockMap, DestLabel, Block),
opt_util.is_sdproceed_next(Block, BetweenBR),
opt_util.filter_out_r1(BetweenFT, yes(SuccessFT), Between),
opt_util.filter_out_r1(BetweenBR, yes(SuccessBR), Between),
(
SuccessFT = llconst_true,
SuccessBR = llconst_false,
code_util.negate_rval(Cond, NewCond)
;
SuccessFT = llconst_false,
SuccessBR = llconst_true,
NewCond = Cond
),
not needs_workaround(reg(reg_r, 1), NewCond)
then
( if NewCond = lval(reg(reg_r, 1)) then
NewAssign = llds_instr(comment("r1 = old r1"), "")
else
NewAssign = llds_instr(assign(reg(reg_r, 1), NewCond),
"shortcircuit bool computation")
),
Proceed = llds_instr(goto(code_succip), "shortcircuit"),
NewInstrs = [NewAssign | Between] ++ [Proceed],
skip_to_next_label(Instrs0, _DeadInstrs, LiveInstrs0),
NewRemain = nr_specified(NewInstrs, LiveInstrs0)
else if
% Try to short-circuit the destination.
TargetLabel \= DestLabel
then
Shorted = "shortcircuited jump: " ++ Comment0,
NewInstrs = [
llds_instr(if_val(Cond, code_label(DestLabel)), Shorted)
],
NewRemain = nr_specified(NewInstrs, Instrs0)
else
NewRemain = nr_usual_case
)
else
NewRemain = nr_usual_case
)
else
NewRemain = nr_usual_case
).
:- pred jump_opt_foreign_proc_code(instr::in(instr_foreign_proc_code),
string::in, list(instruction)::in, instr::in, jump_opt_info::in,
new_remain::out) is det.
jump_opt_foreign_proc_code(Uinstr0, Comment0, Instrs0, _PrevInstr,
JumpOptInfo, NewRemain) :-
Uinstr0 = foreign_proc_code(Decls, Components0, MayCallMercury,
MaybeFixNoLayout, MaybeFixLayout, MaybeFixOnlyLayout,
MaybeNoFix0, MaybeDefLabel, StackSlotRef, MaybeDup),
some [!Redirect] (
InstrMap = JumpOptInfo ^ joi_instr_map,
list.map_foldl(short_circuit_foreign_proc_component(InstrMap),
Components0, Components, no, !:Redirect),
(
MaybeNoFix0 = yes(NoFix),
short_circuit_label(InstrMap, NoFix, NoFixDest),
MaybeNoFix = yes(NoFixDest),
!:Redirect = yes
;
MaybeNoFix0 = no,
MaybeNoFix = no
),
% These sanity checks are too strong, because we don't prohibit labels
% appearing these slots of foreign_proc_code instructions from appearing
% in InstrMap; we only prohibit the use of those entries in InstrMap
% to optimize away these labels.
%
% ( if
% MaybeFixNoLayout = yes(FixNoLayout),
% short_circuit_label(InstrMap, FixNoLayout, FixNoLayoutDest),
% FixNoLayoutDest \= FixNoLayout
% then
% error("jump_opt_instr_list: foreign_proc_code fix_no_layout")
% else
% true
% ),
% ( if
% MaybeFixLayout = yes(FixLayout),
% short_circuit_label(InstrMap, FixLayout, FixLayoutDest),
% FixLayoutDest \= FixLayout
% then
% error("jump_opt_instr_list: foreign_proc_code fix_layout")
% else
% true
% ),
% ( if
% MaybeFixOnlyLayout = yes(FixOnlyLayout),
% short_circuit_label(InstrMap, FixOnlyLayout, FixOnlyLayoutDest),
% FixOnlyLayoutDest \= FixOnlyLayout
% then
% error("jump_opt_instr_list: foreign_proc_code fix_only_layout")
% else
% true
% ),
(
!.Redirect = no,
NewRemain = nr_usual_case
;
!.Redirect = yes,
Comment = Comment0 ++ " (some redirects)",
Uinstr = foreign_proc_code(Decls, Components, MayCallMercury,
MaybeFixNoLayout, MaybeFixLayout, MaybeFixOnlyLayout,
MaybeNoFix, MaybeDefLabel, StackSlotRef, MaybeDup),
Instr = llds_instr(Uinstr, Comment),
NewRemain = nr_specified([Instr], Instrs0)
)
).
:- func block_may_be_duplicated(list(instruction)) = bool.
block_may_be_duplicated([]) = yes.
block_may_be_duplicated([Instr | Instrs]) = BlockMayBeDuplicated :-
Instr = llds_instr(Uinstr, _),
InstrMayBeDuplicated = instr_may_be_duplicated(Uinstr),
(
InstrMayBeDuplicated = no,
BlockMayBeDuplicated = no
;
InstrMayBeDuplicated = yes,
BlockMayBeDuplicated = block_may_be_duplicated(Instrs)
).
:- func instr_may_be_duplicated(instr) = bool.
instr_may_be_duplicated(Instr) = InstrMayBeDuplicated :-
( if Instr ^ fproc_fix_onlylayout = yes(_) then
% This instruction is a trace event. Duplicating it would
% increase code size, and may cost more in locality than
% the benefit represented by the elimination of the jump.
% When debugging is enabled, size is in any case more important
% than the last bit of speed.
InstrMayBeDuplicated = no
else if Instr ^ fproc_maybe_dupl = proc_may_not_duplicate then
InstrMayBeDuplicated = no
else
InstrMayBeDuplicated = yes
).
:- func redirect_comment(string) = string.
redirect_comment(Comment) = Comment ++ " (redirected return)".
% We avoid generating statements that redefine the value of a location
% by comparing its old contents for non-equality with zero.
%
% The reason is that code such as r1 = !r1 causes gcc 2.7 on SPARCs to
% abort with an internal error.
%
% Apparently this is the only place where the Mercury compiler generates
% assignments like that, otherwise we might need a more general work-around
% that worked for code generated by other parts of the compiler as well.
%
% (It is likely that the problem would occur if bool_not was ever inlined
% into a procedure where the value being complemented was already known to
% be false.)
%
:- pred needs_workaround(lval::in, rval::in) is semidet.
needs_workaround(Lval, Cond) :-
(
Cond = unop(logical_not, lval(Lval))
;
Cond = binop(Op, Left, Right),
Op = int_cmp(_, CmpOp),
( CmpOp = eq ; CmpOp = ne ),
(
Right = lval(Lval),
( Left = const(llconst_int(0))
; Left = mkword(ptag(0u8), unop(mkbody, const(llconst_int(0))))
)
;
Left = lval(Lval),
( Right = const(llconst_int(0))
; Right = mkword(ptag(0u8), unop(mkbody, const(llconst_int(0))))
)
)
).
:- pred adjust_livevals(instr::in, list(instruction)::in,
list(instruction)::out) is det.
adjust_livevals(PrevInstr, Instrs0, Instrs) :-
( if
PrevInstr = livevals(PrevLivevals),
opt_util.skip_comments(Instrs0, Instrs1),
Instrs1 = [llds_instr(livevals(BetweenLivevals), _) | Instrs2]
then
( if BetweenLivevals = PrevLivevals then
Instrs = Instrs2
else
unexpected($pred, "BetweenLivevals and PrevLivevals differ")
)
else
Instrs = Instrs0
).
%-----------------------------------------------------------------------------%
% Short-circuit the given label by following any gotos at the
% labelled instruction or by falling through consecutive labels.
%
:- pred short_circuit_label(instrmap::in, label::in, label::out) is det.
short_circuit_label(InstrMap, Label0, Label) :-
( if map.search(InstrMap, Label0, Instr0) then
final_dest(InstrMap, Label0, Label, Instr0, _Instr)
else
Label = Label0
).
% Find the final destination of a given instruction at a given label.
% We follow gotos as well as consecutive labels.
%
:- pred final_dest(instrmap::in, label::in, label::out, instruction::in,
instruction::out) is det.
final_dest(InstrMap, SrcLabel, DestLabel, SrcInstr, DestInstr) :-
final_dest_loop(InstrMap, [], SrcLabel, DestLabel, SrcInstr, DestInstr).
:- pred final_dest_loop(instrmap::in, list(label)::in,
label::in, label::out, instruction::in, instruction::out) is det.
final_dest_loop(InstrMap, LabelsSofar, SrcLabel, DestLabel,
SrcInstr, DestInstr) :-
( if
SrcInstr = llds_instr(SrcUinstr, _Comment),
(
SrcUinstr = goto(code_label(TargetLabel))
;
SrcUinstr = label(TargetLabel)
),
map.search(InstrMap, TargetLabel, TargetInstr),
not list.member(SrcLabel, LabelsSofar)
then
final_dest_loop(InstrMap, [SrcLabel | LabelsSofar],
TargetLabel, DestLabel, TargetInstr, DestInstr)
else
DestLabel = SrcLabel,
DestInstr = SrcInstr
).
%-----------------------------------------------------------------------------%
:- pred short_circuit_maybe_labels(instrmap::in,
list(maybe(label))::in, list(maybe(label))::out) is det.
short_circuit_maybe_labels(_InstrMap, [], []).
short_circuit_maybe_labels(InstrMap, [MaybeLabel0 | MaybeLabels0],
[MaybeLabel | MaybeLabels]) :-
(
MaybeLabel0 = yes(Label0),
short_circuit_label(InstrMap, Label0, Label),
MaybeLabel = yes(Label)
;
MaybeLabel0 = no,
MaybeLabel = no
),
short_circuit_maybe_labels(InstrMap, MaybeLabels0, MaybeLabels).
%-----------------------------------------------------------------------------%
:- pred short_circuit_labels_rval(instrmap::in, rval::in, rval::out) is det.
short_circuit_labels_rval(InstrMap, Rval0, Rval) :-
(
Rval0 = lval(Lval0),
short_circuit_labels_lval(InstrMap, Lval0, Lval),
Rval = lval(Lval)
;
Rval0 = var(_),
unexpected($pred, "var")
;
Rval0 = mkword(Tag, SubRval0),
short_circuit_labels_rval(InstrMap, SubRval0, SubRval),
Rval = mkword(Tag, SubRval)
;
Rval0 = const(Const0),
short_circuit_labels_const(InstrMap, Const0, Const),
Rval = const(Const)
;
Rval0 = cast(Type, SubRval0),
short_circuit_labels_rval(InstrMap, SubRval0, SubRval),
Rval = cast(Type, SubRval)
;
Rval0 = unop(UnOp, SubRval0),
short_circuit_labels_rval(InstrMap, SubRval0, SubRval),
Rval = unop(UnOp, SubRval)
;
Rval0 = binop(BinOp, LRval0, RRval0),
short_circuit_labels_rval(InstrMap, LRval0, LRval),
short_circuit_labels_rval(InstrMap, RRval0, RRval),
Rval = binop(BinOp, LRval, RRval)
;
( Rval0 = mkword_hole(_)
; Rval0 = mem_addr(_)
),
Rval = Rval0
).
:- pred short_circuit_labels_const(instrmap::in,
rval_const::in, rval_const::out) is det.
short_circuit_labels_const(InstrMap, RvalConst0, RvalConst) :-
(
( RvalConst0 = llconst_true
; RvalConst0 = llconst_false
; RvalConst0 = llconst_int(_)
; RvalConst0 = llconst_uint(_)
; RvalConst0 = llconst_int8(_)
; RvalConst0 = llconst_uint8(_)
; RvalConst0 = llconst_int16(_)
; RvalConst0 = llconst_uint16(_)
; RvalConst0 = llconst_int32(_)
; RvalConst0 = llconst_uint32(_)
; RvalConst0 = llconst_int64(_)
; RvalConst0 = llconst_uint64(_)
; RvalConst0 = llconst_foreign(_, _)
; RvalConst0 = llconst_float(_)
; RvalConst0 = llconst_string(_)
; RvalConst0 = llconst_multi_string(_)
; RvalConst0 = llconst_data_addr(_)
; RvalConst0 = llconst_data_addr_word_offset(_, _)
),
RvalConst = RvalConst0
;
RvalConst0 = llconst_code_addr(CodeAddr0),
( if CodeAddr0 = code_label(Label0) then
short_circuit_label(InstrMap, Label0, Label),
CodeAddr = code_label(Label)
else
CodeAddr = CodeAddr0
),
RvalConst = llconst_code_addr(CodeAddr)
).
% Not currently needed.
%
% :- pred short_circuit_labels_maybe_rvals(instrmap::in, list(maybe(rval))::in,
% list(maybe(rval))::out) is det.
%
% short_circuit_labels_maybe_rvals(_, [], []).
% short_circuit_labels_maybe_rvals(InstrMap, [MaybeRval0 | MaybeRvals0],
% [MaybeRval | MaybeRvals]) :-
% short_circuit_labels_maybe_rval(InstrMap, MaybeRval0, MaybeRval),
% short_circuit_labels_maybe_rvals(InstrMap, MaybeRvals0, MaybeRvals).
%
% :- pred short_circuit_labels_maybe_rval(instrmap::in,
% maybe(rval)::in, maybe(rval)::out) is det.
%
% short_circuit_labels_maybe_rval(InstrMap, MaybeRval0, MaybeRval) :-
% (
% MaybeRval0 = no,
% MaybeRval = no
% ;
% MaybeRval0 = yes(Rval0),
% short_circuit_labels_rval(InstrMap, Rval0, Rval),
% MaybeRval = yes(Rval)
% ).
:- pred short_circuit_labels_lval(instrmap::in, lval::in, lval::out) is det.
short_circuit_labels_lval(InstrMap, Lval0, Lval) :-
(
( Lval0 = reg(_T, _N)
; Lval0 = succip
; Lval0 = maxfr
; Lval0 = curfr
; Lval0 = hp
; Lval0 = sp
; Lval0 = parent_sp
; Lval0 = temp(_T, _N)
; Lval0 = stackvar(_N)
; Lval0 = parent_stackvar(_N)
; Lval0 = framevar(_N)
; Lval0 = double_stackvar(_Type, _N)
; Lval0 = global_var_ref(_Var)
),
Lval = Lval0
;
Lval0 = succip_slot(Rval0),
short_circuit_labels_rval(InstrMap, Rval0, Rval),
Lval = succip_slot(Rval)
;
Lval0 = redoip_slot(Rval0),
short_circuit_labels_rval(InstrMap, Rval0, Rval),
Lval = redoip_slot(Rval)
;
Lval0 = redofr_slot(Rval0),
short_circuit_labels_rval(InstrMap, Rval0, Rval),
Lval = redofr_slot(Rval)
;
Lval0 = succfr_slot(Rval0),
short_circuit_labels_rval(InstrMap, Rval0, Rval),
Lval = succfr_slot(Rval)
;
Lval0 = prevfr_slot(Rval0),
short_circuit_labels_rval(InstrMap, Rval0, Rval),
Lval = prevfr_slot(Rval)
;
Lval0 = field(Tag, Rval0, Field0),
short_circuit_labels_rval(InstrMap, Rval0, Rval),
short_circuit_labels_rval(InstrMap, Field0, Field),
Lval = field(Tag, Rval, Field)
;
Lval0 = mem_ref(Rval0),
short_circuit_labels_rval(InstrMap, Rval0, Rval),
Lval = mem_ref(Rval)
;
Lval0 = lvar(_),
unexpected($pred, "lvar")
).
:- pred short_circuit_foreign_proc_component(instrmap::in,
foreign_proc_component::in, foreign_proc_component::out,
bool::in, bool::out) is det.
short_circuit_foreign_proc_component(InstrMap, !Component, !Redirect) :-
(
!.Component = foreign_proc_fail_to(Label0),
short_circuit_label(InstrMap, Label0, Label),
!:Component = foreign_proc_fail_to(Label),
( if Label = Label0 then
true
else
!:Redirect = yes
)
;
( !.Component = foreign_proc_inputs(_)
; !.Component = foreign_proc_outputs(_)
; !.Component = foreign_proc_user_code(_, _, _)
; !.Component = foreign_proc_raw_code(_, _, _, _)
; !.Component = foreign_proc_alloc_id(_)
; !.Component = foreign_proc_noop
)
).
%-----------------------------------------------------------------------------%
:- end_module ll_backend.jumpopt.
%-----------------------------------------------------------------------------%
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