Files
mercury/compiler/middle_rec.m
Zoltan Somogyi 389599b337 Revamped the determinism system.
prog_io, hlds:	Added the functor "multidet" to the type determinism.
		Added types and predicates to relate determinism to its
		two components, can_fail and soln_count.

		Removed the functor "unspecified" from the type determinism,
		substituting maybe(determinism) for determinism in proc_info.

		Replaced the type category with the type code_model,
		and added predicates to compute it from determinism.

det_analysis:	Redone the analyses to work with determinism, not category
		(or code_model). This should enable programmers to write
		their own erroneous (and failure) predicates.

other files:	Use the new and renamed types and access predicates.
1995-04-06 02:13:05 +00:00

405 lines
13 KiB
Mathematica

%---------------------------------------------------------------------------%
% Copyright (C) 1995 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.
%---------------------------------------------------------------------------%
%
% Code generation - do middle recursion optimization
% Main authors: zs and conway.
%
%---------------------------------------------------------------------------%
%---------------------------------------------------------------------------%
:- module middle_rec.
:- interface.
:- import_module hlds, llds, code_info.
:- pred middle_rec__match_det(hlds__goal, hlds__goal, code_info, code_info).
:- mode middle_rec__match_det(in, out, in, out) is semidet.
:- pred middle_rec__gen_det(hlds__goal, code_tree, code_info, code_info).
:- mode middle_rec__gen_det(in, out, in, out) is det.
%---------------------------------------------------------------------------%
%---------------------------------------------------------------------------%
:- implementation.
:- import_module code_gen, unify_gen, set, int.
:- import_module code_util, code_aux, opt_util, std_util, tree, list, require.
%---------------------------------------------------------------------------%
middle_rec__match_det(Goal, Switch, CodeInfo, CodeInfo) :-
Goal = GoalExpr - GoalInfo,
GoalExpr = switch(Var, CanFail, [Case1, Case2]),
CanFail = cannot_fail, % we are in trouble if this fails
Case1 = case(ConsId1, Goal1),
Case2 = case(ConsId2, Goal2),
(
code_aux__contains_only_builtins(Goal1),
code_aux__contains_simple_recursive_call(Goal2, CodeInfo, _)
->
Switch = switch(Var, cannot_fail, [
case(ConsId1, Goal1),
case(ConsId2, Goal2)
]) - GoalInfo
;
code_aux__contains_only_builtins(Goal2),
code_aux__contains_simple_recursive_call(Goal1, CodeInfo, _)
->
Switch = switch(Var, cannot_fail, [
case(ConsId2, Goal2),
case(ConsId1, Goal1)
]) - GoalInfo
;
fail
).
middle_rec__gen_det(Goal, Instrs) -->
(
{ Goal = switch(Var, cannot_fail, [Case1, Case2])
- SwitchGoalInfo},
{ Case1 = case(NonrecConsId, Base) },
{ Case2 = case(_RecConsId, Recursive) }
->
{ goal_info_store_map(SwitchGoalInfo, StoreMap0) },
(
{ StoreMap0 = yes(StoreMap) }
->
code_info__push_store_map(StoreMap)
;
{ true }
),
code_info__get_call_info(CallInfo),
code_info__get_varset(VarSet),
{ code_aux__explain_call_info(CallInfo, VarSet,
CallInfoComment) },
code_info__get_module_info(ModuleInfo),
code_info__get_pred_id(PredId),
code_info__get_proc_id(ProcId),
{ code_util__make_local_entry_label(ModuleInfo, PredId, ProcId,
Entry) },
code_aux__pre_goal_update(SwitchGoalInfo),
code_info__get_next_label(BaseLabel, no),
code_info__push_failure_cont(known(BaseLabel)),
unify_gen__generate_tag_test(Var, NonrecConsId, NegTestCode),
code_info__pop_failure_cont,
{ tree__flatten(NegTestCode, NegTestListList) },
{ list__condense(NegTestListList, NegTestList) },
{ code_util__negate_the_test(NegTestList, EntryTestList) },
code_info__grab_code_info(CodeInfo),
code_gen__generate_forced_det_goal(Base, BaseCodeFrag),
code_info__slap_code_info(CodeInfo),
code_gen__generate_forced_det_goal(Recursive, RecCodeFrag),
code_aux__post_goal_update(SwitchGoalInfo),
code_info__remake_with_store_map,
(
{ StoreMap0 = yes(_StoreMap) }
->
code_info__pop_store_map
;
{ true }
),
code_info__get_arginfo(ArgModes),
code_info__get_headvars(HeadVars),
{ assoc_list__from_corresponding_lists(HeadVars, ArgModes, Args) },
code_info__setup_call(Args, callee, EpilogFrag),
{ code_gen__output_args(Args, LiveArgs) },
{ BaseCode = tree(BaseCodeFrag, EpilogFrag) },
{ RecCode = tree(RecCodeFrag, EpilogFrag) },
{ LiveValCode = [ livevals(LiveArgs) - "" ] },
{ tree__flatten(RecCode, RecListList) },
{ list__condense(RecListList, RecList) },
{ middle_rec__split_rec_code(RecList, BeforeList0, AfterList) },
{ list__append(BeforeList0, AfterList, RecCodeList) },
{ middle_rec__find_unused_register(RecCodeList, AuxReg) },
{ middle_rec__add_counter_to_livevals(BeforeList0, AuxReg,
BeforeList) },
{ tree__flatten(BaseCode, BaseListList) },
{ list__condense(BaseListList, BaseList) },
{ middle_rec__generate_downloop_test(EntryTestList,
Loop1Label, Loop1Test) },
code_info__get_next_label(Loop1Label, no),
code_info__get_next_label(Loop2Label, no),
code_info__get_total_stackslot_count(StackSlots),
( { StackSlots = 0 } ->
{ MaybeIncrSp = [] },
{ MaybeDecrSp = [] },
{ InitAuxReg = [ assign(AuxReg, const(int_const(0)))
- "initialize counter register" ] },
{ IncrAuxReg = [ assign(AuxReg, binop((+),
lval(AuxReg),
const(int_const(1))))
- "increment loop counter" ] },
{ DecrAuxReg = [ assign(AuxReg, binop((-),
lval(AuxReg),
const(int_const(1))))
- "decrement loop counter" ] },
{ TestAuxReg = [ if_val(binop((>),
lval(AuxReg), const(int_const(0))),
label(Loop2Label))
- "test on upward loop" ] }
;
{ MaybeIncrSp = [incr_sp(StackSlots) - ""] },
{ MaybeDecrSp = [decr_sp(StackSlots) - ""] },
{ InitAuxReg = [ assign(AuxReg, lval(sp))
- "initialize counter register" ] },
{ IncrAuxReg = [] },
{ DecrAuxReg = [] },
{ TestAuxReg = [ if_val(binop((>),
lval(sp), lval(AuxReg)),
label(Loop2Label))
- "test on upward loop" ] }
),
{ list__condense([
[
label(Entry) - "Procedure entry point",
comment(CallInfoComment) - ""
],
EntryTestList,
InitAuxReg,
[
label(Loop1Label) - "start of the down loop"
],
MaybeIncrSp,
IncrAuxReg,
BeforeList,
Loop1Test,
BaseList,
[
label(Loop2Label) - ""
],
AfterList,
MaybeDecrSp,
DecrAuxReg,
TestAuxReg,
LiveValCode,
[
goto(succip, succip) -
"exit from recursive case",
label(BaseLabel) - "start of base case"
],
BaseList,
LiveValCode,
[
goto(succip, succip) - "exit from base case"
]
], InstrList) },
{ Instrs = node(InstrList) }
;
{ error("middle_rec__gen_det match failed") }
).
:- pred middle_rec__generate_downloop_test(list(instruction), label,
list(instruction)).
:- mode middle_rec__generate_downloop_test(in, in, out) is det.
middle_rec__generate_downloop_test([], _, _) :-
error("middle_rec__generate_downloop_test on empty list").
middle_rec__generate_downloop_test([Instr0 | Instrs0], Target, Instrs) :-
( Instr0 = if_val(Test, _OldTarget) - _Comment ->
( Instrs0 = [] ->
true
;
error("middle_rec__generate_downloop_test: if_val followed by other instructions")
),
code_util__neg_rval(Test, NewTest),
Instrs = [if_val(NewTest, label(Target)) - "test on downward loop"]
;
middle_rec__generate_downloop_test(Instrs0, Target, Instrs1),
Instrs = [Instr0 | Instrs1]
).
%---------------------------------------------------------------------------%
:- pred middle_rec__split_rec_code(list(instruction),
list(instruction), list(instruction)).
:- mode middle_rec__split_rec_code(in, out, out) is det.
middle_rec__split_rec_code([], _, _) :-
error("did not find call in middle_rec__split_rec_code").
middle_rec__split_rec_code([Instr0 | Instrs1], Before, After) :-
( Instr0 = call(_, _, _, _) - _ ->
(
opt_util__skip_comments(Instrs1, Instrs2),
Instrs2 = [Instr2 | Instrs3],
Instr2 = label(_) - _
->
Before = [],
After = Instrs3
;
error("call not followed by label in middle_rec__split_rec_code")
)
;
middle_rec__split_rec_code(Instrs1, Before1, After),
Before = [Instr0 | Before1]
).
%---------------------------------------------------------------------------%
:- pred middle_rec__add_counter_to_livevals(list(instruction), lval,
list(instruction)).
:- mode middle_rec__add_counter_to_livevals(in, in, out) is det.
middle_rec__add_counter_to_livevals([], _Lval, []).
middle_rec__add_counter_to_livevals([I0|Is0], Lval, [I|Is]) :-
(
I0 = livevals(Lives0) - Comment
->
set__insert(Lives0, Lval, Lives),
I = livevals(Lives) - Comment
;
I = I0
),
middle_rec__add_counter_to_livevals(Is0, Lval, Is).
%---------------------------------------------------------------------------%
:- pred middle_rec__find_unused_register(list(instruction), lval).
:- mode middle_rec__find_unused_register(in, out) is det.
middle_rec__find_unused_register(Instrs, UnusedReg) :-
set__init(Used0),
middle_rec__find_used_registers(Instrs, Used0, Used1),
set__to_sorted_list(Used1, UsedList),
middle_rec__find_unused_register_2(UsedList, 1, UnusedReg).
:- pred middle_rec__find_unused_register_2(list(int), int, lval).
:- mode middle_rec__find_unused_register_2(in, in, out) is det.
middle_rec__find_unused_register_2([], N, reg(r(N))).
middle_rec__find_unused_register_2([H | T], N, Reg) :-
( N < H ->
Reg = reg(r(N))
;
N1 is N + 1,
middle_rec__find_unused_register_2(T, N1, Reg)
).
:- pred middle_rec__find_used_registers(list(instruction), set(int), set(int)).
:- mode middle_rec__find_used_registers(in, di, uo) is det.
middle_rec__find_used_registers([], Used, Used).
middle_rec__find_used_registers([Instr - _ | Instrs], Used0, Used) :-
middle_rec__find_used_registers_instr(Instr, Used0, Used1),
middle_rec__find_used_registers(Instrs, Used1, Used).
:- pred middle_rec__find_used_registers_instr(instr, set(int), set(int)).
:- mode middle_rec__find_used_registers_instr(in, di, uo) is det.
middle_rec__find_used_registers_instr(comment(_), Used, Used).
middle_rec__find_used_registers_instr(livevals(LvalSet), Used0, Used) :-
set__to_sorted_list(LvalSet, LvalList),
middle_rec__find_used_registers_lvals(LvalList, Used0, Used).
middle_rec__find_used_registers_instr(block(_, Instrs), Used0, Used) :-
middle_rec__find_used_registers(Instrs, Used0, Used).
middle_rec__find_used_registers_instr(assign(Lval, Rval), Used0, Used) :-
middle_rec__find_used_registers_lval(Lval, Used0, Used1),
middle_rec__find_used_registers_rval(Rval, Used1, Used).
middle_rec__find_used_registers_instr(call(_, _, _, _), Used, Used).
middle_rec__find_used_registers_instr(call_closure(_, _, _), Used, Used).
middle_rec__find_used_registers_instr(mkframe(_, _, _), Used, Used).
middle_rec__find_used_registers_instr(modframe(_), Used, Used).
middle_rec__find_used_registers_instr(label(_), Used, Used).
middle_rec__find_used_registers_instr(goto(_, _), Used, Used).
middle_rec__find_used_registers_instr(computed_goto(Rval, _), Used0, Used) :-
middle_rec__find_used_registers_rval(Rval, Used0, Used).
middle_rec__find_used_registers_instr(c_code(_), Used, Used).
middle_rec__find_used_registers_instr(if_val(Rval, _), Used0, Used) :-
middle_rec__find_used_registers_rval(Rval, Used0, Used).
middle_rec__find_used_registers_instr(incr_hp(Lval, _, Rval), Used0, Used) :-
middle_rec__find_used_registers_lval(Lval, Used0, Used1),
middle_rec__find_used_registers_rval(Rval, Used1, Used).
middle_rec__find_used_registers_instr(mark_hp(Lval), Used0, Used) :-
middle_rec__find_used_registers_lval(Lval, Used0, Used).
middle_rec__find_used_registers_instr(restore_hp(Rval), Used0, Used) :-
middle_rec__find_used_registers_rval(Rval, Used0, Used).
middle_rec__find_used_registers_instr(incr_sp(_), Used, Used).
middle_rec__find_used_registers_instr(decr_sp(_), Used, Used).
:- pred middle_rec__find_used_registers_lvals(list(lval), set(int), set(int)).
:- mode middle_rec__find_used_registers_lvals(in, di, uo) is det.
middle_rec__find_used_registers_lvals([], Used, Used).
middle_rec__find_used_registers_lvals([Lval | Lvals], Used0, Used) :-
middle_rec__find_used_registers_lval(Lval, Used0, Used1),
middle_rec__find_used_registers_lvals(Lvals, Used1, Used).
:- pred middle_rec__find_used_registers_lval(lval, set(int), set(int)).
:- mode middle_rec__find_used_registers_lval(in, di, uo) is det.
middle_rec__find_used_registers_lval(Lval, Used0, Used) :-
( Lval = reg(r(N)) ->
set__insert(Used0, N, Used)
; Lval = field(_, Rval, FieldNum) ->
middle_rec__find_used_registers_rval(Rval, Used0, Used1),
middle_rec__find_used_registers_rval(FieldNum, Used1, Used)
; Lval = lvar(_) ->
error("lvar found in middle_rec__find_used_registers_lval")
;
Used = Used0
).
:- pred middle_rec__find_used_registers_rval(rval, set(int), set(int)).
:- mode middle_rec__find_used_registers_rval(in, di, uo) is det.
middle_rec__find_used_registers_rval(Rval, Used0, Used) :-
(
Rval = lval(Lval),
middle_rec__find_used_registers_lval(Lval, Used0, Used)
;
Rval = var(_),
error("var found in middle_rec__find_used_registers_rval")
;
Rval = create(_, MaybeRvals, _),
middle_rec__find_used_registers_maybe_rvals(MaybeRvals,
Used0, Used)
;
Rval = mkword(_, Rval1),
middle_rec__find_used_registers_rval(Rval1, Used0, Used)
;
Rval = const(_),
Used = Used0
;
Rval = unop(_, Rval1),
middle_rec__find_used_registers_rval(Rval1, Used0, Used)
;
Rval = binop(_, Rval1, Rval2),
middle_rec__find_used_registers_rval(Rval1, Used0, Used1),
middle_rec__find_used_registers_rval(Rval2, Used1, Used)
).
:- pred middle_rec__find_used_registers_maybe_rvals(list(maybe(rval)),
set(int), set(int)).
:- mode middle_rec__find_used_registers_maybe_rvals(in, di, uo) is det.
middle_rec__find_used_registers_maybe_rvals([], Used, Used).
middle_rec__find_used_registers_maybe_rvals([MaybeRval | MaybeRvals],
Used0, Used) :-
(
MaybeRval = no,
Used1 = Used0
;
MaybeRval = yes(Rval),
middle_rec__find_used_registers_rval(Rval, Used0, Used1)
),
middle_rec__find_used_registers_maybe_rvals(MaybeRvals, Used1, Used).