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Estimated hours taken: 6 Branches: main This diff changes the LLDS backend to make it easier to read and to maintain, but contains no changes in algorithms whatsoever. compiler/basic_block.m: compiler/dupelim.m: compiler/frameopt.m: compiler/jumpopt.m: compiler/layout_out.m: compiler/livemap.m: compiler/peephole.m: compiler/reassign.m: compiler/rtti_out.m: compiler/use_local_vars.m: Convert these modules to our current coding standards. Use state variable notation when appropriate, reordering arguments as necessary. compiler/llds_out.m: Convert these modules to our current coding standards. Use state variable notation when appropriate, reordering arguments as necessary. Delete predicates which are just specialized forms of foldl, using foldl (or foldl2 etc) directly instead. Factor out some common code. compiler/livemap.m: Convert these modules to our current coding standards. Use state variable notation when appropriate, reordering arguments as necessary. Remove some special case handling that used to be required by the value numbering pass. library/bintree_set.m: Provide a function version of the initialization predicate.
452 lines
15 KiB
Mathematica
452 lines
15 KiB
Mathematica
%-----------------------------------------------------------------------------%
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% Copyright (C) 1995-2003 The University of Melbourne.
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% This file may only be copied under the terms of the GNU General
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% Public License - see the file COPYING in the Mercury distribution.
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%-----------------------------------------------------------------------------%
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%
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% File: livemap.m
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%
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% Main author: zs.
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%
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% This module builds up a map that gives the set of live lvals at each label.
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%-----------------------------------------------------------------------------%
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:- module ll_backend__livemap.
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:- interface.
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:- import_module ll_backend__llds.
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:- import_module list, set, map, std_util.
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:- type livemap == map(label, lvalset).
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:- type lvalset == set(lval).
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% Given a list of instructions defining a procedure, return a map
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% giving the set of live non-field lvals at each label.
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%
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% We can compute this set only if the procedure contains no C code.
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:- pred livemap__build(list(instruction)::in, maybe(livemap)::out) is det.
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:- implementation.
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:- import_module ll_backend__opt_util.
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:- import_module require, string, bool.
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%-----------------------------------------------------------------------------%
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%-----------------------------------------------------------------------------%
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% The method we follow is a backward scan of the instruction list,
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% keeping track of the set of live lvals as we go. We update this set
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% at each instruction. When we get to a label, we know that this set
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% of lvals is live at that label.
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%
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% At instructions that can branch away, every lval that is live at
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% any possible target is live before that instruction. Since some
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% branches may be backward branches, we may not have seen the branch
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% target when we process the branch. Therefore we have to repeat the
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% scan, this time with more knowledge about more labels, until we
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% get to a fixpoint.
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livemap__build(Instrs, MaybeLivemap) :-
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map__init(Livemap0),
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list__reverse(Instrs, BackInstrs),
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livemap__build_2(BackInstrs, Livemap0, MaybeLivemap).
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:- pred livemap__build_2(list(instruction)::in, livemap::in,
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maybe(livemap)::out) is det.
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livemap__build_2(Backinstrs, Livemap0, MaybeLivemap) :-
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set__init(Livevals0),
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livemap__build_livemap(Backinstrs, Livevals0, no, ContainsUserCode,
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Livemap0, Livemap1),
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( ContainsUserCode = yes ->
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MaybeLivemap = no
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; livemap__equal_livemaps(Livemap0, Livemap1) ->
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MaybeLivemap = yes(Livemap1)
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;
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livemap__build_2(Backinstrs, Livemap1, MaybeLivemap)
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).
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% Check whether the two livemaps agree on the set of live lvals
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% at every label. They must agree on the set of labels as well.
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% This is important. Livemap1 will be empty in the first call,
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% so agreement only on the set of labels in Livemap1 is useless.
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% The domain of Livemap2 should always be every label in the procedure.
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% as should the domain of Livemap1 in every call after the first.
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:- pred livemap__equal_livemaps(livemap::in, livemap::in) is semidet.
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livemap__equal_livemaps(Livemap1, Livemap2) :-
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map__keys(Livemap1, Labels),
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map__keys(Livemap2, Labels),
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livemap__equal_livemaps_keys(Labels, Livemap1, Livemap2).
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:- pred livemap__equal_livemaps_keys(list(label)::in, livemap::in, livemap::in)
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is semidet.
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livemap__equal_livemaps_keys([], _Livemap1, _Livemap2).
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livemap__equal_livemaps_keys([Label | Labels], Livemap1, Livemap2) :-
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map__lookup(Livemap1, Label, Liveset1),
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map__lookup(Livemap2, Label, Liveset2),
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set__equal(Liveset1, Liveset2),
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livemap__equal_livemaps_keys(Labels, Livemap1, Livemap2).
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%-----------------------------------------------------------------------------%
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%-----------------------------------------------------------------------------%
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% Build up a map of what lvals are live at each label.
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% The input instruction sequence is reversed.
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:- pred livemap__build_livemap(list(instruction)::in, lvalset::in,
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bool::in, bool::out, livemap::in, livemap::out) is det.
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livemap__build_livemap([], _, !ContainsUserCode, !Livemap).
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livemap__build_livemap([Instr0 | Instrs0], Livevals0,
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!ContainsUserCode, !Livemap) :-
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livemap__build_livemap_instr(Instr0, Instrs0, Instrs1,
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Livevals0, Livevals1, !ContainsUserCode, !Livemap),
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livemap__build_livemap(Instrs1, Livevals1, !ContainsUserCode, !Livemap).
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:- pred livemap__build_livemap_instr(instruction::in, list(instruction)::in,
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list(instruction)::out, lvalset::in, lvalset::out,
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bool::in, bool::out, livemap::in, livemap::out) is det.
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livemap__build_livemap_instr(Instr0, !Instrs, !Livevals, !ContainsUserCode,
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!Livemap) :-
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Instr0 = Uinstr0 - _,
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(
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Uinstr0 = comment(_)
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;
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Uinstr0 = livevals(_),
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error("livevals found in backward scan in build_livemap")
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;
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Uinstr0 = block(_, _, _),
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error("block found in backward scan in build_livemap")
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;
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Uinstr0 = assign(Lval, Rval),
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% Make dead the variable assigned, but make any variables
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% needed to access it live. Make the variables in the assigned
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% expression live as well.
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% The deletion has to be done first. If the assigned-to lval
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% appears on the right hand side as well as the left, then we
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% want make_live to put it back into the liveval set.
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set__delete(!.Livevals, Lval, !:Livevals),
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opt_util__lval_access_rvals(Lval, Rvals),
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livemap__make_live_in_rvals([Rval | Rvals], !Livevals)
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;
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Uinstr0 = call(_, _, _, _, _, _),
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livemap__look_for_livevals(!Instrs, !Livevals, "call", yes, _)
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;
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Uinstr0 = mkframe(_, _)
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;
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Uinstr0 = label(Label),
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map__set(!.Livemap, Label, !.Livevals, !:Livemap)
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;
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Uinstr0 = goto(CodeAddr),
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opt_util__livevals_addr(CodeAddr, LivevalsNeeded),
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livemap__look_for_livevals(!Instrs, !Livevals, "goto",
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LivevalsNeeded, Found),
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( Found = yes ->
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true
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; CodeAddr = label(Label) ->
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livemap__insert_label_livevals([Label], !.Livemap,
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set__init, !:Livevals)
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;
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( CodeAddr = do_redo
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; CodeAddr = do_fail
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; CodeAddr = do_not_reached
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)
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->
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true
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;
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error("unknown label type in build_livemap")
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),
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livemap__special_code_addr(CodeAddr, MaybeSpecial),
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( MaybeSpecial = yes(Special) ->
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set__insert(!.Livevals, Special, !:Livevals)
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;
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true
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)
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;
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Uinstr0 = computed_goto(Rval, Labels),
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livemap__make_live_in_rvals([Rval], set__init, !:Livevals),
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livemap__insert_label_livevals(Labels, !.Livemap, !Livevals)
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;
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Uinstr0 = if_val(Rval, CodeAddr),
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Livevals0 = !.Livevals,
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livemap__look_for_livevals(!Instrs, !Livevals, "if_val",
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no, Found),
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(
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Found = yes,
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% This if_val was put here by middle_rec.
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% We must make sure that the locations mentioned
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% in the livevals annotation become live,
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% since they will be needed at CodeAddr.
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% The locations in Livevals0 may be needed
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% in the fall-through continuation.
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set__union(Livevals0, !Livevals)
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;
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Found = no,
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livemap__make_live_in_rvals([Rval], !Livevals),
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( CodeAddr = label(Label) ->
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livemap__insert_label_livevals([Label],
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!.Livemap, !Livevals)
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;
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true
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)
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),
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livemap__special_code_addr(CodeAddr, MaybeSpecial),
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( MaybeSpecial = yes(Special) ->
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set__insert(!.Livevals, Special, !:Livevals)
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;
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true
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)
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;
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Uinstr0 = incr_hp(Lval, _, _, Rval, _),
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% Make dead the variable assigned, but make any variables
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% needed to access it live. Make the variables in the size
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% expression live as well.
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% The use of the size rval occurs after the assignment
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% to lval, but the two should never have any variables in
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% common. This is why doing the deletion first works.
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set__delete(!.Livevals, Lval, !:Livevals),
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opt_util__lval_access_rvals(Lval, Rvals),
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livemap__make_live_in_rvals([Rval | Rvals], !Livevals)
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;
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Uinstr0 = mark_hp(Lval),
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set__delete(!.Livevals, Lval, !:Livevals),
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opt_util__lval_access_rvals(Lval, Rvals),
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livemap__make_live_in_rvals(Rvals, !Livevals)
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;
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Uinstr0 = restore_hp(Rval),
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livemap__make_live_in_rvals([Rval], !Livevals)
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;
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Uinstr0 = free_heap(Rval),
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livemap__make_live_in_rvals([Rval], !Livevals)
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;
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Uinstr0 = store_ticket(Lval),
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set__delete(!.Livevals, Lval, !:Livevals),
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opt_util__lval_access_rvals(Lval, Rvals),
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livemap__make_live_in_rvals(Rvals, !Livevals)
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;
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Uinstr0 = reset_ticket(Rval, _Reason),
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livemap__make_live_in_rval(Rval, !Livevals)
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;
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Uinstr0 = discard_ticket
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;
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Uinstr0 = prune_ticket
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;
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Uinstr0 = mark_ticket_stack(Lval),
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set__delete(!.Livevals, Lval, !:Livevals),
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opt_util__lval_access_rvals(Lval, Rvals),
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livemap__make_live_in_rvals(Rvals, !Livevals)
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;
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Uinstr0 = prune_tickets_to(Rval),
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livemap__make_live_in_rval(Rval, !Livevals)
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;
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Uinstr0 = incr_sp(_, _)
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;
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Uinstr0 = decr_sp(_)
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;
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Uinstr0 = init_sync_term(_, _)
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;
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Uinstr0 = fork(_, _, _)
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;
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Uinstr0 = join_and_terminate(_)
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;
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Uinstr0 = join_and_continue(_, _)
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;
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Uinstr0 = c_code(_, LiveLvalInfo),
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livemap__build_live_lval_info(LiveLvalInfo,
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!Livevals, !ContainsUserCode)
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;
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Uinstr0 = pragma_c(_, Components, _, _, _, _, _, _),
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livemap__build_livemap_pragma_components(Components,
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!Livevals, !ContainsUserCode)
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).
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:- pred livemap__build_livemap_pragma_components(list(pragma_c_component)::in,
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lvalset::in, lvalset::out, bool::in, bool::out) is det.
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livemap__build_livemap_pragma_components([], !Livevals, !ContainsUserCode).
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livemap__build_livemap_pragma_components([Component | Components],
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!Livevals, !ContainsUserCode) :-
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(
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Component = pragma_c_inputs(Inputs),
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livemap__build_livemap_pragma_inputs(Inputs,
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!Livevals)
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;
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Component = pragma_c_outputs(_)
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;
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Component = pragma_c_user_code(_, _),
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!:ContainsUserCode = yes
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;
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Component = pragma_c_raw_code(_, LiveLvalInfo),
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livemap__build_live_lval_info(LiveLvalInfo,
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!Livevals, !ContainsUserCode)
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;
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Component = pragma_c_fail_to(_)
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;
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Component = pragma_c_noop
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),
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livemap__build_livemap_pragma_components(Components,
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!Livevals, !ContainsUserCode).
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:- pred livemap__build_live_lval_info(c_code_live_lvals::in,
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lvalset::in, lvalset::out, bool::in, bool::out) is det.
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livemap__build_live_lval_info(no_live_lvals_info, !Livevals, _, yes).
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livemap__build_live_lval_info(live_lvals_info(LiveLvalSet), !Livevals,
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!DontValueNumber) :-
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set__to_sorted_list(LiveLvalSet, LiveLvals),
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livemap__insert_proper_livevals(LiveLvals, !Livevals).
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:- pred livemap__build_livemap_pragma_inputs(list(pragma_c_input)::in,
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lvalset::in, lvalset::out) is det.
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livemap__build_livemap_pragma_inputs([], !Livevals).
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livemap__build_livemap_pragma_inputs([Input | Inputs], !Livevals) :-
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Input = pragma_c_input(_, _, Rval, _),
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( Rval = lval(Lval) ->
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livemap__insert_proper_liveval(Lval, !Livevals)
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;
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true
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),
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livemap__build_livemap_pragma_inputs(Inputs, !Livevals).
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:- pred livemap__look_for_livevals(list(instruction)::in,
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list(instruction)::out, lvalset::in, lvalset::out, string::in,
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bool::in, bool::out) is det.
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livemap__look_for_livevals(Instrs0, Instrs, !Livevals,
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Site, Compulsory, Found) :-
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opt_util__skip_comments(Instrs0, Instrs1),
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( Instrs1 = [livevals(Livevals1) - _ | Instrs2] ->
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livemap__filter_livevals(Livevals1, !:Livevals),
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Instrs = Instrs2,
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Found = yes
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; Compulsory = yes ->
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string__append(Site, " not preceded by livevals", Msg),
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error(Msg)
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;
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Instrs = Instrs1,
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Found = no
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).
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% What lval (if any) is consulted when we branch to a code address?
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:- pred livemap__special_code_addr(code_addr::in, maybe(lval)::out) is det.
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livemap__special_code_addr(label(_), no).
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livemap__special_code_addr(imported(_), no).
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livemap__special_code_addr(succip, yes(succip)).
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livemap__special_code_addr(do_succeed(_), yes(succip(lval(curfr)))).
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livemap__special_code_addr(do_redo, yes(redoip(lval(maxfr)))).
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livemap__special_code_addr(do_trace_redo_fail_shallow, no).
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livemap__special_code_addr(do_trace_redo_fail_deep, no).
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livemap__special_code_addr(do_fail, no).
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livemap__special_code_addr(do_call_closure, no).
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livemap__special_code_addr(do_call_class_method, no).
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livemap__special_code_addr(do_not_reached, no).
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%-----------------------------------------------------------------------------%
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%-----------------------------------------------------------------------------%
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:- pred livemap__make_live_in_rvals(list(rval)::in, lvalset::in, lvalset::out)
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is det.
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livemap__make_live_in_rvals([], !Live).
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livemap__make_live_in_rvals([Rval | Rvals], !Live) :-
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livemap__make_live_in_rval(Rval, !Live),
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livemap__make_live_in_rvals(Rvals, !Live).
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% Set all lvals found in this rval to live, with the exception of
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% fields, since they are treated specially (the later stages consider
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% them to be live even if they are not explicitly in the live set).
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:- pred livemap__make_live_in_rval(rval::in, lvalset::in, lvalset::out) is det.
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livemap__make_live_in_rval(lval(Lval), !Live) :-
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% XXX maybe we should treat mem_refs the same way as field refs
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( Lval = field(_, _, _) ->
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true
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;
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set__insert(!.Live, Lval, !:Live)
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),
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opt_util__lval_access_rvals(Lval, AccessRvals),
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livemap__make_live_in_rvals(AccessRvals, !Live).
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livemap__make_live_in_rval(mkword(_, Rval), !Live) :-
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livemap__make_live_in_rval(Rval, !Live).
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livemap__make_live_in_rval(const(_), !Live).
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livemap__make_live_in_rval(unop(_, Rval), !Live) :-
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livemap__make_live_in_rval(Rval, !Live).
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livemap__make_live_in_rval(binop(_, Rval1, Rval2), !Live) :-
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livemap__make_live_in_rval(Rval1, !Live),
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livemap__make_live_in_rval(Rval2, !Live).
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livemap__make_live_in_rval(var(_), _, _) :-
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error("var rval should not propagate to the optimizer").
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livemap__make_live_in_rval(mem_addr(MemRef), !Live) :-
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livemap__make_live_in_mem_ref(MemRef, !Live).
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:- pred livemap__make_live_in_mem_ref(mem_ref::in, lvalset::in, lvalset::out)
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is det.
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livemap__make_live_in_mem_ref(stackvar_ref(_), !Live).
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livemap__make_live_in_mem_ref(framevar_ref(_), !Live).
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livemap__make_live_in_mem_ref(heap_ref(Rval, _, _), !Live) :-
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livemap__make_live_in_rval(Rval, !Live).
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%-----------------------------------------------------------------------------%
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%-----------------------------------------------------------------------------%
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:- pred livemap__filter_livevals(lvalset::in, lvalset::out) is det.
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livemap__filter_livevals(Livevals0, Livevals) :-
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set__to_sorted_list(Livevals0, Livelist),
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set__init(Livevals1),
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livemap__insert_proper_livevals(Livelist, Livevals1, Livevals).
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:- pred livemap__insert_label_livevals(list(label)::in, livemap::in,
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lvalset::in, lvalset::out) is det.
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livemap__insert_label_livevals([], _, !Livevals).
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livemap__insert_label_livevals([Label | Labels], Livemap, !Livevals) :-
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( map__search(Livemap, Label, LabelLivevals) ->
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set__to_sorted_list(LabelLivevals, Livelist),
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livemap__insert_proper_livevals(Livelist, !Livevals)
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;
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true
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),
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livemap__insert_label_livevals(Labels, Livemap, !Livevals).
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:- pred livemap__insert_proper_livevals(list(lval)::in, lvalset::in,
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lvalset::out) is det.
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livemap__insert_proper_livevals([], !Livevals).
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livemap__insert_proper_livevals([Live | Livelist], !Livevals) :-
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livemap__insert_proper_liveval(Live, !Livevals),
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livemap__insert_proper_livevals(Livelist, !Livevals).
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% Don't insert references to locations on the heap.
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:- pred livemap__insert_proper_liveval(lval::in, lvalset::in, lvalset::out)
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is det.
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livemap__insert_proper_liveval(Live, !Livevals) :-
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|
( Live = field(_, _, _) ->
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true
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|
;
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set__insert(!.Livevals, Live, !:Livevals)
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|
).
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%-----------------------------------------------------------------------------%
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%-----------------------------------------------------------------------------%
|