mercury/compiler/code_util.m

%-----------------------------------------------------------------------------%
% vim: ft=mercury ts=4 sw=4 et
%-----------------------------------------------------------------------------%
% Copyright (C) 1994-2011 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.
%-----------------------------------------------------------------------------%
% 
% File: code_util.m.
% 
% Various utilities routines for code generation and recognition of builtins.
% 
%-----------------------------------------------------------------------------%

:- module ll_backend.code_util.
:- interface.

:- import_module hlds.hlds_goal.
:- import_module hlds.hlds_llds.
:- import_module hlds.hlds_module.
:- import_module hlds.hlds_pred.
:- import_module hlds.hlds_rtti.
:- import_module ll_backend.llds.
:- import_module mdbcomp.prim_data.
:- import_module parse_tree.prog_data.

:- import_module assoc_list.
:- import_module bool.
:- import_module list.
:- import_module maybe.
:- import_module pair.

%-----------------------------------------------------------------------------%

    % Create a code address which holds the address of the specified procedure.
    % The `immed' argument should be `no' if the the caller wants the returned
    % address to be valid from everywhere in the program. If being valid from
    % within the current procedure is enough, this argument should be `yes'
    % wrapped around the value of the --procs-per-c-function option and the
    % current procedure id. Using an address that is only valid from within
    % the current procedure may make jumps more efficient.
    %
:- type immed == maybe(pair(int, pred_proc_id)).
:- func make_entry_label(module_info, pred_id, proc_id, immed) = code_addr.

:- func make_entry_label_from_rtti(rtti_proc_label, immed) = code_addr.

    % Create a label which holds the address of the specified procedure,
    % which must be defined in the current module (procedures that are
    % imported from other modules have representations only as code_addrs,
    % not as labels, since their address is not known at C compilation time).
    % The fourth argument has the same meaning as for make_entry_label.
    %
:- func make_local_entry_label(module_info, pred_id, proc_id, immed) = label.

    % Create a label internal to a Mercury procedure.
    %
:- func make_internal_label(module_info, pred_id, proc_id, int) = label.

:- func extract_proc_label_from_code_addr(code_addr) = proc_label.

:- pred arg_loc_to_register(arg_loc::in, lval::out) is det.

:- pred max_mentioned_reg(list(lval)::in, int::out) is det.
:- pred max_mentioned_abs_reg(list(abs_locn)::in, int::out) is det.

:- pred goal_may_alloc_temp_frame(hlds_goal::in, bool::out) is det.

    % Negate a condition.
    % This is used mostly just to make the generated code more readable.
    %
:- pred neg_rval(rval::in, rval::out) is det.

:- pred negate_the_test(list(instruction)::in, list(instruction)::out) is det.

    % These predicates return the set of lvals referenced in an rval
    % and an lval respectively. Lvals referenced indirectly through
    % lvals of the form var(_) are not counted.
    %
:- func lvals_in_rval(rval) = list(lval).
:- func lvals_in_lval(lval) = list(lval).
:- func lvals_in_lvals(list(lval)) = list(lval).

    % Given a procedure that already has its arg_info field filled in,
    % return a list giving its input variables and their initial locations.
    %
:- pred build_input_arg_list(proc_info::in, assoc_list(prog_var, lval)::out)
    is det.

:- func size_of_cell_args(list(cell_arg)) = int.

%---------------------------------------------------------------------------%
%---------------------------------------------------------------------------%

:- implementation.

:- import_module backend_libs.builtin_ops.
:- import_module backend_libs.proc_label.
:- import_module hlds.code_model.

:- import_module int.
:- import_module require.
:- import_module term.

%---------------------------------------------------------------------------%

make_entry_label(ModuleInfo, PredId, ProcId, Immed) = ProcAddr :-
    RttiProcLabel = make_rtti_proc_label(ModuleInfo, PredId, ProcId),
    ProcAddr = make_entry_label_from_rtti(RttiProcLabel, Immed).

make_entry_label_from_rtti(RttiProcLabel, Immed) = ProcAddr :-
    ProcIsImported = RttiProcLabel ^ rpl_proc_is_imported,
    (
        ProcIsImported = yes,
        ProcLabel = make_proc_label_from_rtti(RttiProcLabel),
        ProcAddr = code_imported_proc(ProcLabel)
    ;
        ProcIsImported = no,
        Label = make_local_entry_label_from_rtti(RttiProcLabel, Immed),
        ProcAddr = code_label(Label)
    ).

make_local_entry_label(ModuleInfo, PredId, ProcId, Immed) = Label :-
    RttiProcLabel = make_rtti_proc_label(ModuleInfo, PredId, ProcId),
    Label = make_local_entry_label_from_rtti(RttiProcLabel, Immed).

:- func make_local_entry_label_from_rtti(rtti_proc_label, immed) = label.

make_local_entry_label_from_rtti(RttiProcLabel, Immed) = Label :-
    ProcLabel = make_proc_label_from_rtti(RttiProcLabel),
    (
        Immed = no,
        % If we want to define the label or use it to put it into a data
        % structure, a label that is usable only within the current C module
        % won't do.
        ProcIsExported = RttiProcLabel ^ rpl_proc_is_exported,
        (
            ProcIsExported = yes,
            EntryType = entry_label_exported
        ;
            ProcIsExported = no,
            EntryType = entry_label_local
        ),
        Label = entry_label(EntryType, ProcLabel)
    ;
        Immed = yes(ProcsPerFunc - proc(CurPredId, CurProcId)),
        Label = choose_local_label_type(ProcsPerFunc, CurPredId, CurProcId,
            RttiProcLabel ^ rpl_pred_id, RttiProcLabel ^ rpl_proc_id,
            ProcLabel)
    ).

:- func choose_local_label_type(int, pred_id, proc_id, pred_id, proc_id,
        proc_label) = label.

choose_local_label_type(ProcsPerFunc, CurPredId, CurProcId,
        PredId, ProcId, ProcLabel) = Label :-
    (
        % If we want to branch to the label now, we prefer a form that is
        % usable only within the current C module, since it is likely to be
        % faster.
        (
            ProcsPerFunc = 0
        ;
            PredId = CurPredId,
            ProcId = CurProcId
        )
    ->
        EntryType = entry_label_c_local
    ;
        EntryType = entry_label_local
    ),
    Label = entry_label(EntryType, ProcLabel).

%-----------------------------------------------------------------------------%

make_internal_label(ModuleInfo, PredId, ProcId, LabelNum) = Label :-
    ProcLabel = make_proc_label(ModuleInfo, PredId, ProcId),
    Label = internal_label(LabelNum, ProcLabel).

extract_proc_label_from_code_addr(CodeAddr) = ProcLabel :-
    ( CodeAddr = code_label(Label) ->
        ProcLabel = get_proc_label(Label)
    ; CodeAddr = code_imported_proc(ProcLabelPrime) ->
        ProcLabel = ProcLabelPrime
    ;
        unexpected($module, $pred, "failed")
    ).

%-----------------------------------------------------------------------------%

arg_loc_to_register(ArgLoc, reg(reg_r, ArgLoc)).

%-----------------------------------------------------------------------------%

max_mentioned_reg(Lvals, MaxRegNum) :-
    max_mentioned_reg_2(Lvals, 0, MaxRegNum).

:- pred max_mentioned_reg_2(list(lval)::in, int::in, int::out) is det.

max_mentioned_reg_2([], !MaxRegNum).
max_mentioned_reg_2([Lval | Lvals], !MaxRegNum) :-
    ( Lval = reg(reg_r, N) ->
        int.max(N, !MaxRegNum)
    ;
        true
    ),
    max_mentioned_reg_2(Lvals, !MaxRegNum).

max_mentioned_abs_reg(Lvals, MaxRegNum) :-
    max_mentioned_abs_reg_2(Lvals, 0, MaxRegNum).

:- pred max_mentioned_abs_reg_2(list(abs_locn)::in, int::in, int::out) is det.

max_mentioned_abs_reg_2([], !MaxRegNum).
max_mentioned_abs_reg_2([Lval | Lvals], !MaxRegNum) :-
    ( Lval = abs_reg(N) ->
        int.max(N, !MaxRegNum)
    ;
        true
    ),
    max_mentioned_abs_reg_2(Lvals, !MaxRegNum).

%-----------------------------------------------------------------------------%

goal_may_alloc_temp_frame(hlds_goal(GoalExpr, _GoalInfo), May) :-
    goal_may_alloc_temp_frame_2(GoalExpr, May).

:- pred goal_may_alloc_temp_frame_2(hlds_goal_expr::in, bool::out)
    is det.

goal_may_alloc_temp_frame_2(generic_call(_, _, _, _), no).
goal_may_alloc_temp_frame_2(plain_call(_, _, _, _, _, _), no).
goal_may_alloc_temp_frame_2(unify(_, _, _, _, _), no).
    % We cannot safely say that a foreign code fragment does not allocate
    % temporary nondet frames without knowing all the #defined macros
    % that expand to mktempframe and variants thereof. The performance
    % impact of being too conservative is probably not too bad.
goal_may_alloc_temp_frame_2(call_foreign_proc(_, _, _, _, _, _, _), yes).
goal_may_alloc_temp_frame_2(scope(_, Goal), May) :-
    Goal = hlds_goal(_, GoalInfo),
    CodeModel = goal_info_get_code_model(GoalInfo),
    (
        CodeModel = model_non,
        May = yes
    ;
        ( CodeModel = model_det
        ; CodeModel = model_semi
        ),
        goal_may_alloc_temp_frame(Goal, May)
    ).
goal_may_alloc_temp_frame_2(negation(Goal), May) :-
    goal_may_alloc_temp_frame(Goal, May).
goal_may_alloc_temp_frame_2(conj(_ConjType, Goals), May) :-
    goal_list_may_alloc_temp_frame(Goals, May).
goal_may_alloc_temp_frame_2(disj(Goals), May) :-
    goal_list_may_alloc_temp_frame(Goals, May).
goal_may_alloc_temp_frame_2(switch(_Var, _Det, Cases), May) :-
    cases_may_alloc_temp_frame(Cases, May).
goal_may_alloc_temp_frame_2(if_then_else(_Vars, C, T, E), May) :-
    ( goal_may_alloc_temp_frame(C, yes) ->
        May = yes
    ; goal_may_alloc_temp_frame(T, yes) ->
        May = yes
    ;
        goal_may_alloc_temp_frame(E, May)
    ).
goal_may_alloc_temp_frame_2(shorthand(_), _) :-
    % These should have been expanded out by now.
    unexpected($module, $pred, "shorthand").

:- pred goal_list_may_alloc_temp_frame(list(hlds_goal)::in, bool::out) is det.

goal_list_may_alloc_temp_frame([], no).
goal_list_may_alloc_temp_frame([Goal | Goals], May) :-
    ( goal_may_alloc_temp_frame(Goal, yes) ->
        May = yes
    ;
        goal_list_may_alloc_temp_frame(Goals, May)
    ).

:- pred cases_may_alloc_temp_frame(list(case)::in, bool::out) is det.

cases_may_alloc_temp_frame([], no).
cases_may_alloc_temp_frame([case(_, _, Goal) | Cases], May) :-
    ( goal_may_alloc_temp_frame(Goal, yes) ->
        May = yes
    ;
        cases_may_alloc_temp_frame(Cases, May)
    ).

%-----------------------------------------------------------------------------%

neg_rval(Rval, NegRval) :-
    ( neg_rval_2(Rval, NegRval0) ->
        NegRval = NegRval0
    ;
        NegRval = unop(logical_not, Rval)
    ).

:- pred neg_rval_2(rval::in, rval::out) is semidet.

neg_rval_2(const(Const), const(NegConst)) :-
    (
        Const = llconst_true,
        NegConst = llconst_false
    ;
        Const = llconst_false,
        NegConst = llconst_true
    ).
neg_rval_2(unop(logical_not, Rval), Rval).
neg_rval_2(binop(Op, X, Y), binop(NegOp, X, Y)) :-
    neg_op(Op, NegOp).

:- pred neg_op(binary_op::in, binary_op::out) is semidet.

neg_op(eq, ne).
neg_op(ne, eq).
neg_op(int_lt, int_ge).
neg_op(int_le, int_gt).
neg_op(int_gt, int_le).
neg_op(int_ge, int_lt).
neg_op(str_eq, str_ne).
neg_op(str_ne, str_eq).
neg_op(str_lt, str_ge).
neg_op(str_le, str_gt).
neg_op(str_gt, str_le).
neg_op(str_ge, str_lt).
neg_op(float_eq, float_ne).
neg_op(float_ne, float_eq).
neg_op(float_lt, float_ge).
neg_op(float_le, float_gt).
neg_op(float_gt, float_le).
neg_op(float_ge, float_lt).

negate_the_test([], _) :-
    unexpected($module, $pred, "empty list").
negate_the_test([Instr0 | Instrs0], Instrs) :-
    ( Instr0 = llds_instr(if_val(Test, Target), Comment) ->
        neg_rval(Test, NewTest),
        Instrs = [llds_instr(if_val(NewTest, Target), Comment)]
    ;
        negate_the_test(Instrs0, Instrs1),
        Instrs = [Instr0 | Instrs1]
    ).

%-----------------------------------------------------------------------------%

lvals_in_lvals([]) = [].
lvals_in_lvals([First | Rest]) = FirstLvals ++ RestLvals :-
    FirstLvals = lvals_in_lval(First),
    RestLvals = lvals_in_lvals(Rest).

lvals_in_rval(lval(Lval)) = [Lval | lvals_in_lval(Lval)].
lvals_in_rval(var(_)) = [].
lvals_in_rval(mkword(_, Rval)) = lvals_in_rval(Rval).
lvals_in_rval(const(_)) = [].
lvals_in_rval(unop(_, Rval)) = lvals_in_rval(Rval).
lvals_in_rval(binop(_, Rval1, Rval2)) =
    lvals_in_rval(Rval1) ++ lvals_in_rval(Rval2).
lvals_in_rval(mem_addr(MemRef)) = lvals_in_mem_ref(MemRef).

lvals_in_lval(reg(_, _)) = [].
lvals_in_lval(stackvar(_)) = [].
lvals_in_lval(parent_stackvar(_)) = [].
lvals_in_lval(framevar(_)) = [].
lvals_in_lval(succip) = [].
lvals_in_lval(maxfr) = [].
lvals_in_lval(curfr) = [].
lvals_in_lval(succip_slot(Rval)) = lvals_in_rval(Rval).
lvals_in_lval(redofr_slot(Rval)) = lvals_in_rval(Rval).
lvals_in_lval(redoip_slot(Rval)) = lvals_in_rval(Rval).
lvals_in_lval(succfr_slot(Rval)) = lvals_in_rval(Rval).
lvals_in_lval(prevfr_slot(Rval)) = lvals_in_rval(Rval).
lvals_in_lval(hp) = [].
lvals_in_lval(sp) = [].
lvals_in_lval(parent_sp) = [].
lvals_in_lval(field(_, Rval1, Rval2)) =
    lvals_in_rval(Rval1) ++ lvals_in_rval(Rval2).
lvals_in_lval(lvar(_)) = [].
lvals_in_lval(temp(_, _)) = [].
lvals_in_lval(mem_ref(Rval)) = lvals_in_rval(Rval).
lvals_in_lval(global_var_ref(_)) = [].

:- func lvals_in_mem_ref(mem_ref) = list(lval).

lvals_in_mem_ref(stackvar_ref(Rval)) = lvals_in_rval(Rval).
lvals_in_mem_ref(framevar_ref(Rval)) = lvals_in_rval(Rval).
lvals_in_mem_ref(heap_ref(Rval1, _, Rval2)) =
    lvals_in_rval(Rval1) ++ lvals_in_rval(Rval2).

%-----------------------------------------------------------------------------%

build_input_arg_list(ProcInfo, VarLvals) :-
    proc_info_get_headvars(ProcInfo, HeadVars),
    proc_info_arg_info(ProcInfo, ArgInfos),
    assoc_list.from_corresponding_lists(HeadVars, ArgInfos, VarArgInfos),
    build_input_arg_list_2(VarArgInfos, VarLvals).

:- pred build_input_arg_list_2(assoc_list(prog_var, arg_info)::in,
    assoc_list(prog_var, lval)::out) is det.

build_input_arg_list_2([], []).
build_input_arg_list_2([V - Arg | Rest0], VarArgs) :-
    Arg = arg_info(Loc, Mode),
    (
        Mode = top_in,
        arg_loc_to_register(Loc, Reg),
        VarArgs = [V - Reg | VarArgs0]
    ;
        ( Mode = top_out
        ; Mode = top_unused
        ),
        VarArgs = VarArgs0
    ),
    build_input_arg_list_2(Rest0, VarArgs0).

%-----------------------------------------------------------------------------%

size_of_cell_args([]) = 0.
size_of_cell_args([CellArg | CellArgs]) = Size + Sizes :-
    (
        ( CellArg = cell_arg_full_word(_, _)
        ; CellArg = cell_arg_take_addr(_, _)
        ; CellArg = cell_arg_skip
        ),
        Size = 1
    ;
        CellArg = cell_arg_double_word(_),
        Size = 2
    ),
    Sizes = size_of_cell_args(CellArgs).

%-----------------------------------------------------------------------------%
:- end_module ll_backend.code_util.
%-----------------------------------------------------------------------------%