aboutsummaryrefslogtreecommitdiffstats
path: root/lib/compiler/src/beam_ssa.erl
diff options
context:
space:
mode:
Diffstat (limited to 'lib/compiler/src/beam_ssa.erl')
-rw-r--r--lib/compiler/src/beam_ssa.erl889
1 files changed, 889 insertions, 0 deletions
diff --git a/lib/compiler/src/beam_ssa.erl b/lib/compiler/src/beam_ssa.erl
new file mode 100644
index 0000000000..0f662d851d
--- /dev/null
+++ b/lib/compiler/src/beam_ssa.erl
@@ -0,0 +1,889 @@
+%%
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 2018. All Rights Reserved.
+%%
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%% http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%%
+%% %CopyrightEnd%
+%%
+%% Purpose: Type definitions and utilities for the SSA format.
+
+-module(beam_ssa).
+-export([add_anno/3,get_anno/2,get_anno/3,
+ clobbers_xregs/1,def/2,def_used/2,
+ definitions/1,
+ dominators/1,common_dominators/3,
+ flatmapfold_instrs_rpo/4,
+ fold_po/3,fold_po/4,fold_rpo/3,fold_rpo/4,
+ fold_instrs_rpo/4,
+ linearize/1,
+ mapfold_blocks_rpo/4,
+ mapfold_instrs_rpo/4,
+ normalize/1,
+ no_side_effect/1,
+ predecessors/1,
+ rename_vars/3,
+ rpo/1,rpo/2,
+ split_blocks/3,
+ successors/1,successors/2,
+ trim_unreachable/1,
+ update_phi_labels/4,used/1,
+ uses/1,uses/2]).
+
+-export_type([b_module/0,b_function/0,b_blk/0,b_set/0,
+ b_ret/0,b_br/0,b_switch/0,terminator/0,
+ b_var/0,b_literal/0,b_remote/0,b_local/0,
+ value/0,argument/0,label/0,
+ var_name/0,var_base/0,literal_value/0,
+ op/0,anno/0,block_map/0,dominator_map/0,
+ rename_map/0,rename_proplist/0,usage_map/0,
+ definition_map/0]).
+
+-include("beam_ssa.hrl").
+
+-type b_module() :: #b_module{}.
+-type b_function() :: #b_function{}.
+-type b_blk() :: #b_blk{}.
+-type b_set() :: #b_set{}.
+
+-type b_br() :: #b_br{}.
+-type b_ret() :: #b_ret{}.
+-type b_switch() :: #b_switch{}.
+-type terminator() :: b_br() | b_ret() | b_switch().
+
+-type construct() :: b_module() | b_function() | b_blk() | b_set() |
+ terminator().
+
+-type b_var() :: #b_var{}.
+-type b_literal() :: #b_literal{}.
+-type b_remote() :: #b_remote{}.
+-type b_local() :: #b_local{}.
+
+-type value() :: b_var() | b_literal().
+-type phi_value() :: {value(),label()}.
+-type argument() :: value() | b_remote() | b_local() | phi_value().
+-type label() :: non_neg_integer().
+
+-type var_name() :: var_base() | {var_base(),non_neg_integer()}.
+-type var_base() :: atom() | non_neg_integer().
+
+-type literal_value() :: atom() | integer() | float() | list() |
+ nil() | tuple() | map() | binary().
+
+-type op() :: {'bif',atom()} | {'float',float_op()} | prim_op() | cg_prim_op().
+-type anno() :: #{atom() := any()}.
+
+-type block_map() :: #{label():=b_blk()}.
+-type dominator_map() :: #{label():=[label()]}.
+-type numbering_map() :: #{label():=non_neg_integer()}.
+-type usage_map() :: #{b_var():=[{label(),b_set() | terminator()}]}.
+-type definition_map() :: #{b_var():=b_set()}.
+-type rename_map() :: #{b_var():=value()}.
+-type rename_proplist() :: [{b_var(),value()}].
+
+%% Note: By default, dialyzer will collapse this type to atom().
+%% To avoid the collapsing, change the value of SET_LIMIT to 50 in the
+%% file erl_types.erl in the hipe application.
+
+-type prim_op() :: 'bs_add' | 'bs_extract' | 'bs_init' | 'bs_init_writable' |
+ 'bs_match' | 'bs_put' | 'bs_start_match' | 'bs_test_tail' |
+ 'bs_utf16_size' | 'bs_utf8_size' | 'build_stacktrace' |
+ 'call' | 'catch_end' |
+ 'extract' |
+ 'get_hd' | 'get_map_element' | 'get_tl' | 'get_tuple_element' |
+ 'has_map_field' |
+ 'is_nonempty_list' | 'is_tagged_tuple' |
+ 'kill_try_tag' |
+ 'landingpad' |
+ 'make_fun' | 'new_try_tag' |
+ 'peek_message' | 'phi' | 'put_list' | 'put_map' | 'put_tuple' |
+ 'raw_raise' | 'recv_next' | 'remove_message' | 'resume' |
+ 'set_tuple_element' | 'succeeded' |
+ 'timeout' |
+ 'wait' | 'wait_timeout'.
+
+-type float_op() :: 'checkerror' | 'clearerror' | 'convert' | 'get' | 'put' |
+ '+' | '-' | '*' | '/'.
+
+%% Primops only used internally during code generation.
+-type cg_prim_op() :: 'bs_get' | 'bs_match_string' | 'bs_restore' | 'bs_skip' |
+ 'copy' | 'put_tuple_arity' | 'put_tuple_element'.
+
+-import(lists, [foldl/3,keyfind/3,mapfoldl/3,member/2,reverse/1]).
+
+-spec add_anno(Key, Value, Construct) -> Construct when
+ Key :: atom(),
+ Value :: any(),
+ Construct :: construct().
+
+add_anno(Key, Val, #b_function{anno=Anno}=Bl) ->
+ Bl#b_function{anno=Anno#{Key=>Val}};
+add_anno(Key, Val, #b_blk{anno=Anno}=Bl) ->
+ Bl#b_blk{anno=Anno#{Key=>Val}};
+add_anno(Key, Val, #b_set{anno=Anno}=Bl) ->
+ Bl#b_set{anno=Anno#{Key=>Val}};
+add_anno(Key, Val, #b_br{anno=Anno}=Bl) ->
+ Bl#b_br{anno=Anno#{Key=>Val}};
+add_anno(Key, Val, #b_ret{anno=Anno}=Bl) ->
+ Bl#b_ret{anno=Anno#{Key=>Val}};
+add_anno(Key, Val, #b_switch{anno=Anno}=Bl) ->
+ Bl#b_switch{anno=Anno#{Key=>Val}}.
+
+-spec get_anno(atom(), construct()) -> any().
+
+get_anno(Key, Construct) ->
+ map_get(Key, get_anno(Construct)).
+
+-spec get_anno(atom(), construct(),any()) -> any().
+
+get_anno(Key, Construct, Default) ->
+ maps:get(Key, get_anno(Construct), Default).
+
+get_anno(#b_function{anno=Anno}) -> Anno;
+get_anno(#b_blk{anno=Anno}) -> Anno;
+get_anno(#b_set{anno=Anno}) -> Anno;
+get_anno(#b_br{anno=Anno}) -> Anno;
+get_anno(#b_ret{anno=Anno}) -> Anno;
+get_anno(#b_switch{anno=Anno}) -> Anno.
+
+%% clobbers_xregs(#b_set{}) -> true|false.
+%% Test whether the instruction invalidates all X registers.
+
+-spec clobbers_xregs(b_set()) -> boolean().
+
+clobbers_xregs(#b_set{op=Op}) ->
+ case Op of
+ bs_init_writable -> true;
+ build_stacktrace -> true;
+ call -> true;
+ landingpad -> true;
+ make_fun -> true;
+ peek_message -> true;
+ raw_raise -> true;
+ _ -> false
+ end.
+
+%% no_side_effect(#b_set{}) -> true|false.
+%% Test whether this instruction has no side effect and thus is safe
+%% not to execute if its value is not used. Note that even if `true`
+%% is returned, the instruction could still be impure (e.g. bif:get).
+
+-spec no_side_effect(b_set()) -> boolean().
+
+no_side_effect(#b_set{op=Op}) ->
+ case Op of
+ {bif,_} -> true;
+ {float,get} -> true;
+ bs_init -> true;
+ bs_extract -> true;
+ bs_match -> true;
+ bs_start_match -> true;
+ bs_test_tail -> true;
+ bs_get_tail -> true;
+ bs_put -> true;
+ extract -> true;
+ get_hd -> true;
+ get_tl -> true;
+ get_map_element -> true;
+ get_tuple_element -> true;
+ has_map_field -> true;
+ is_nonempty_list -> true;
+ is_tagged_tuple -> true;
+ make_fun -> true;
+ put_map -> true;
+ put_list -> true;
+ put_tuple -> true;
+ succeeded -> true;
+ _ -> false
+ end.
+
+-spec predecessors(Blocks) -> #{BlockNumber:=[Predecessor]} when
+ Blocks :: block_map(),
+ BlockNumber :: label(),
+ Predecessor :: label().
+
+predecessors(Blocks) ->
+ P0 = [{S,L} || {L,Blk} <- maps:to_list(Blocks),
+ S <- successors(Blk)],
+ P1 = sofs:relation(P0),
+ P2 = sofs:rel2fam(P1),
+ P3 = sofs:to_external(P2),
+ P = [{0,[]}|P3],
+ maps:from_list(P).
+
+-spec successors(b_blk()) -> [label()].
+
+successors(#b_blk{last=Terminator}) ->
+ case Terminator of
+ #b_br{bool=#b_literal{val=true},succ=Succ} ->
+ [Succ];
+ #b_br{bool=#b_literal{val=false},fail=Fail} ->
+ [Fail];
+ #b_br{succ=Succ,fail=Fail} ->
+ [Fail,Succ];
+ #b_switch{fail=Fail,list=List} ->
+ [Fail|[L || {_,L} <- List]];
+ #b_ret{} ->
+ []
+ end.
+
+%% normalize(Instr0) -> Instr.
+%% Normalize instructions to help optimizations.
+%%
+%% For commutative operators (such as '+' and 'or'), always
+%% place a variable operand before a literal operand.
+%%
+%% Normalize #b_br{} to one of the following forms:
+%%
+%% #b_br{b_literal{val=true},succ=Label,fail=Label}
+%% #b_br{b_var{},succ=Label1,fail=Label2} where Label1 =/= Label2
+%%
+%% Simplify a #b_switch{} with a literal argument to a #b_br{}.
+%%
+%% Simplify a #b_switch{} with a variable argument and an empty
+%% switch list to a #b_br{}.
+
+-spec normalize(b_set() | terminator()) ->
+ b_set() | terminator().
+
+normalize(#b_set{op={bif,Bif},args=Args}=Set) ->
+ case {is_commutative(Bif),Args} of
+ {false,_} ->
+ Set;
+ {true,[#b_literal{}=Lit,#b_var{}=Var]} ->
+ Set#b_set{args=[Var,Lit]};
+ {true,_} ->
+ Set
+ end;
+normalize(#b_set{}=Set) ->
+ Set;
+normalize(#b_br{}=Br) ->
+ case Br of
+ #b_br{bool=Bool,succ=Same,fail=Same} ->
+ case Bool of
+ #b_literal{val=true} ->
+ Br;
+ _ ->
+ Br#b_br{bool=#b_literal{val=true}}
+ end;
+ #b_br{bool=#b_literal{val=true},succ=Succ} ->
+ Br#b_br{fail=Succ};
+ #b_br{bool=#b_literal{val=false},fail=Fail} ->
+ Br#b_br{bool=#b_literal{val=true},succ=Fail};
+ #b_br{} ->
+ Br
+ end;
+normalize(#b_switch{arg=Arg,fail=Fail,list=List}=Sw) ->
+ case Arg of
+ #b_literal{} ->
+ case keyfind(Arg, 1, List) of
+ false ->
+ #b_br{bool=#b_literal{val=true},succ=Fail,fail=Fail};
+ {Arg,L} ->
+ #b_br{bool=#b_literal{val=true},succ=L,fail=L}
+ end;
+ #b_var{} when List =:= [] ->
+ #b_br{bool=#b_literal{val=true},succ=Fail,fail=Fail};
+ #b_var{} ->
+ Sw
+ end;
+normalize(#b_ret{}=Ret) ->
+ Ret.
+
+-spec successors(label(), block_map()) -> [label()].
+
+successors(L, Blocks) ->
+ successors(map_get(L, Blocks)).
+
+-spec def(Ls, Blocks) -> Def when
+ Ls :: [label()],
+ Blocks :: block_map(),
+ Def :: ordsets:ordset(var_name()).
+
+def(Ls, Blocks) ->
+ Top = rpo(Ls, Blocks),
+ Blks = [map_get(L, Blocks) || L <- Top],
+ def_1(Blks, []).
+
+-spec def_used(Ls, Blocks) -> {Def,Used} when
+ Ls :: [label()],
+ Blocks :: block_map(),
+ Def :: ordsets:ordset(var_name()),
+ Used :: ordsets:ordset(var_name()).
+
+def_used(Ls, Blocks) ->
+ Top = rpo(Ls, Blocks),
+ Blks = [map_get(L, Blocks) || L <- Top],
+ Preds = cerl_sets:from_list(Top),
+ def_used_1(Blks, Preds, [], []).
+
+%% dominators(BlockMap) -> {Dominators,Numbering}.
+%% Calculate the dominator tree, returning a map where each entry
+%% in the map is a list that gives the path from that block to
+%% the top of the dominator tree. (Note that the suffixes of the
+%% paths are shared with each other, which make the representation
+%% of the dominator tree highly memory-efficient.)
+%%
+%% The implementation is based on:
+%%
+%% http://www.hipersoft.rice.edu/grads/publications/dom14.pdf
+%% Cooper, Keith D.; Harvey, Timothy J; Kennedy, Ken (2001).
+%% A Simple, Fast Dominance Algorithm.
+
+-spec dominators(Blocks) -> Result when
+ Blocks :: block_map(),
+ Result :: {dominator_map(), numbering_map()}.
+dominators(Blocks) ->
+ Preds = predecessors(Blocks),
+ Top0 = rpo(Blocks),
+ Df = maps:from_list(number(Top0, 0)),
+ [{0,[]}|Top] = [{L,map_get(L, Preds)} || L <- Top0],
+
+ %% The flow graph for an Erlang function is reducible, and
+ %% therefore one traversal in reverse postorder is sufficient.
+ Acc = #{0=>[0]},
+ {dominators_1(Top, Df, Acc),Df}.
+
+%% common_dominators([Label], Dominators, Numbering) -> [Label].
+%% Calculate the common dominators for the given list of blocks
+%% and Dominators and Numbering as returned from dominators/1.
+
+-spec common_dominators([label()], dominator_map(), numbering_map()) -> [label()].
+common_dominators(Ls, Dom, Numbering) ->
+ Doms = [map_get(L, Dom) || L <- Ls],
+ dom_intersection(Doms, Numbering).
+
+-spec fold_instrs_rpo(Fun, From, Acc0, Blocks) -> any() when
+ Fun :: fun((b_blk()|terminator(), any()) -> any()),
+ From :: [label()],
+ Acc0 :: any(),
+ Blocks :: block_map().
+
+fold_instrs_rpo(Fun, From, Acc0, Blocks) ->
+ Top = rpo(From, Blocks),
+ fold_instrs_rpo_1(Top, Fun, Blocks, Acc0).
+
+%% Like mapfold_instrs_rpo but at the block level to support lookahead and
+%% scope-dependent transformations.
+-spec mapfold_blocks_rpo(Fun, From, Acc, Blocks) -> Result when
+ Fun :: fun((label(), b_blk(), any()) -> {b_blk(), any()}),
+ From :: [label()],
+ Acc :: any(),
+ Blocks :: block_map(),
+ Result :: {block_map(), any()}.
+mapfold_blocks_rpo(Fun, From, Acc, Blocks) ->
+ Successors = rpo(From, Blocks),
+ foldl(fun(Lbl, A) ->
+ mapfold_blocks_rpo_1(Fun, Lbl, A)
+ end, {Blocks, Acc}, Successors).
+
+mapfold_blocks_rpo_1(Fun, Lbl, {Blocks0, Acc0}) ->
+ Block0 = map_get(Lbl, Blocks0),
+ {Block, Acc} = Fun(Lbl, Block0, Acc0),
+ Blocks = Blocks0#{Lbl:=Block},
+ {Blocks, Acc}.
+
+-spec mapfold_instrs_rpo(Fun, From, Acc0, Blocks0) -> {Blocks,Acc} when
+ Fun :: fun((b_blk()|terminator(), any()) -> any()),
+ From :: [label()],
+ Acc0 :: any(),
+ Acc :: any(),
+ Blocks0 :: block_map(),
+ Blocks :: block_map().
+
+mapfold_instrs_rpo(Fun, From, Acc0, Blocks) ->
+ Top = rpo(From, Blocks),
+ mapfold_instrs_rpo_1(Top, Fun, Blocks, Acc0).
+
+-spec flatmapfold_instrs_rpo(Fun, From, Acc0, Blocks0) -> {Blocks,Acc} when
+ Fun :: fun((b_blk()|terminator(), any()) -> any()),
+ From :: [label()],
+ Acc0 :: any(),
+ Acc :: any(),
+ Blocks0 :: block_map(),
+ Blocks :: block_map().
+
+flatmapfold_instrs_rpo(Fun, From, Acc0, Blocks) ->
+ Top = rpo(From, Blocks),
+ flatmapfold_instrs_rpo_1(Top, Fun, Blocks, Acc0).
+
+-type fold_fun() :: fun((label(), b_blk(), any()) -> any()).
+
+%% fold_rpo(Fun, [Label], Acc0, Blocks) -> Acc.
+%% Fold over all blocks a reverse postorder traversal of the block
+%% graph; that is, first visit a block, then visit its successors.
+
+-spec fold_rpo(Fun, Acc0, Blocks) -> any() when
+ Fun :: fold_fun(),
+ Acc0 :: any(),
+ Blocks :: #{label():=b_blk()}.
+
+fold_rpo(Fun, Acc0, Blocks) ->
+ fold_rpo(Fun, [0], Acc0, Blocks).
+
+%% fold_rpo(Fun, [Label], Acc0, Blocks) -> Acc. Fold over all blocks
+%% reachable from a given set of labels in a reverse postorder
+%% traversal of the block graph; that is, first visit a block, then
+%% visit its successors.
+
+-spec fold_rpo(Fun, Labels, Acc0, Blocks) -> any() when
+ Fun :: fold_fun(),
+ Labels :: [label()],
+ Acc0 :: any(),
+ Blocks :: #{label():=b_blk()}.
+
+fold_rpo(Fun, From, Acc0, Blocks) ->
+ Top = rpo(From, Blocks),
+ fold_rpo_1(Top, Fun, Blocks, Acc0).
+
+%% fold_po(Fun, Acc0, Blocks) -> Acc.
+%% Fold over all blocks in a postorder traversal of the block graph;
+%% that is, first visit all successors of block, then the block
+%% itself.
+
+-spec fold_po(Fun, Acc0, Blocks) -> any() when
+ Fun :: fold_fun(),
+ Acc0 :: any(),
+ Blocks :: #{label():=b_blk()}.
+
+%% fold_po(Fun, From, Acc0, Blocks) -> Acc.
+%% Fold over the blocks reachable from the block numbers given
+%% by From in a postorder traversal of the block graph.
+
+fold_po(Fun, Acc0, Blocks) ->
+ fold_po(Fun, [0], Acc0, Blocks).
+
+-spec fold_po(Fun, Labels, Acc0, Blocks) -> any() when
+ Fun :: fold_fun(),
+ Labels :: [label()],
+ Acc0 :: any(),
+ Blocks :: block_map().
+
+fold_po(Fun, From, Acc0, Blocks) ->
+ Top = reverse(rpo(From, Blocks)),
+ fold_rpo_1(Top, Fun, Blocks, Acc0).
+
+%% linearize(Blocks) -> [{BlockLabel,#b_blk{}}].
+%% Linearize the intermediate representation of the code.
+%% Unreachable blocks will be discarded, and phi nodes will
+%% be adjusted so that they no longer refers to discarded
+%% blocks or to blocks that no longer are predecessors of
+%% the phi node block.
+
+-spec linearize(Blocks) -> Linear when
+ Blocks :: block_map(),
+ Linear :: [{label(),b_blk()}].
+
+linearize(Blocks) ->
+ Seen = cerl_sets:new(),
+ {Linear0,_} = linearize_1([0], Blocks, Seen, []),
+ Linear = fix_phis(Linear0, #{}),
+ Linear.
+
+-spec rpo(Blocks) -> [Label] when
+ Blocks :: block_map(),
+ Label :: label().
+
+rpo(Blocks) ->
+ rpo([0], Blocks).
+
+-spec rpo(From, Blocks) -> Labels when
+ From :: [label()],
+ Blocks :: block_map(),
+ Labels :: [label()].
+
+rpo(From, Blocks) ->
+ Seen = cerl_sets:new(),
+ {Ls,_} = rpo_1(From, Blocks, Seen, []),
+ Ls.
+
+-spec rename_vars(Rename, [label()], block_map()) -> block_map() when
+ Rename :: rename_map() | rename_proplist().
+
+rename_vars(Rename, From, Blocks) when is_list(Rename) ->
+ rename_vars(maps:from_list(Rename), From, Blocks);
+rename_vars(Rename, From, Blocks) when is_map(Rename)->
+ Top = rpo(From, Blocks),
+ Preds = cerl_sets:from_list(Top),
+ F = fun(#b_set{op=phi,args=Args0}=Set) ->
+ Args = rename_phi_vars(Args0, Preds, Rename),
+ Set#b_set{args=Args};
+ (#b_set{args=Args0}=Set) ->
+ Args = [rename_var(A, Rename) || A <- Args0],
+ Set#b_set{args=Args};
+ (#b_switch{arg=Bool}=Sw) ->
+ Sw#b_switch{arg=rename_var(Bool, Rename)};
+ (#b_br{bool=Bool}=Br) ->
+ Br#b_br{bool=rename_var(Bool, Rename)};
+ (#b_ret{arg=Arg}=Ret) ->
+ Ret#b_ret{arg=rename_var(Arg, Rename)}
+ end,
+ map_instrs_1(Top, F, Blocks).
+
+%% split_blocks(Predicate, Blocks0, Count0) -> {Blocks,Count}.
+%% Call Predicate(Instruction) for each instruction in all
+%% blocks. If Predicate/1 returns true, split the block
+%% before this instruction.
+
+-spec split_blocks(Pred, Blocks0, Count0) -> {Blocks,Count} when
+ Pred :: fun((b_set()) -> boolean()),
+ Blocks :: block_map(),
+ Count0 :: beam_ssa:label(),
+ Blocks0 :: block_map(),
+ Blocks :: block_map(),
+ Count :: beam_ssa:label().
+
+split_blocks(P, Blocks, Count) ->
+ Ls = beam_ssa:rpo(Blocks),
+ split_blocks_1(Ls, P, Blocks, Count).
+
+-spec trim_unreachable(Blocks0) -> Blocks when
+ Blocks0 :: block_map(),
+ Blocks :: block_map().
+
+%% trim_unreachable(Blocks0) -> Blocks.
+%% Remove all unreachable blocks. Adjust all phi nodes so
+%% they don't refer to blocks that has been removed or no
+%% no longer branch to the phi node in question.
+
+trim_unreachable(Blocks) ->
+ %% Could perhaps be optimized if there is any need.
+ maps:from_list(linearize(Blocks)).
+
+%% update_phi_labels([BlockLabel], Old, New, Blocks0) -> Blocks.
+%% In the given blocks, replace label Old in with New in all
+%% phi nodes. This is useful after merging or splitting
+%% blocks.
+
+-spec update_phi_labels(From, Old, New, Blocks0) -> Blocks when
+ From :: [label()],
+ Old :: label(),
+ New :: label(),
+ Blocks0 :: block_map(),
+ Blocks :: block_map().
+
+update_phi_labels([L|Ls], Old, New, Blocks0) ->
+ case Blocks0 of
+ #{L:=#b_blk{is=[#b_set{op=phi}|_]=Is0}=Blk0} ->
+ Is = update_phi_labels_is(Is0, Old, New),
+ Blk = Blk0#b_blk{is=Is},
+ Blocks = Blocks0#{L:=Blk},
+ update_phi_labels(Ls, Old, New, Blocks);
+ #{L:=#b_blk{}} ->
+ %% No phi nodes in this block.
+ update_phi_labels(Ls, Old, New, Blocks0)
+ end;
+update_phi_labels([], _, _, Blocks) -> Blocks.
+
+-spec used(b_blk() | b_set() | terminator()) -> [var_name()].
+
+used(#b_blk{is=Is,last=Last}) ->
+ used_1([Last|Is], ordsets:new());
+used(#b_br{bool=#b_var{}=V}) ->
+ [V];
+used(#b_ret{arg=#b_var{}=V}) ->
+ [V];
+used(#b_set{op=phi,args=Args}) ->
+ ordsets:from_list([V || {#b_var{}=V,_} <- Args]);
+used(#b_set{args=Args}) ->
+ ordsets:from_list(used_args(Args));
+used(#b_switch{arg=#b_var{}=V}) ->
+ [V];
+used(_) -> [].
+
+-spec definitions(Blocks :: block_map()) -> definition_map().
+definitions(Blocks) ->
+ fold_instrs_rpo(fun(#b_set{ dst = Var }=I, Acc) ->
+ Acc#{Var => I};
+ (_Terminator, Acc) ->
+ Acc
+ end, [0], #{}, Blocks).
+
+-spec uses(Blocks :: block_map()) -> usage_map().
+uses(Blocks) ->
+ uses([0], Blocks).
+
+-spec uses(From, Blocks) -> usage_map() when
+ From :: [label()],
+ Blocks :: block_map().
+uses(From, Blocks) ->
+ fold_rpo(fun fold_uses_block/3, From, #{}, Blocks).
+
+fold_uses_block(Lbl, #b_blk{is=Is,last=Last}, UseMap0) ->
+ F = fun(I, UseMap) ->
+ foldl(fun(Var, Acc) ->
+ Uses0 = maps:get(Var, Acc, []),
+ Uses = [{Lbl, I} | Uses0],
+ maps:put(Var, Uses, Acc)
+ end, UseMap, used(I))
+ end,
+ F(Last, foldl(F, UseMap0, Is)).
+
+%%%
+%%% Internal functions.
+%%%
+
+is_commutative('and') -> true;
+is_commutative('or') -> true;
+is_commutative('xor') -> true;
+is_commutative('band') -> true;
+is_commutative('bor') -> true;
+is_commutative('bxor') -> true;
+is_commutative('+') -> true;
+is_commutative('*') -> true;
+is_commutative('=:=') -> true;
+is_commutative('==') -> true;
+is_commutative('=/=') -> true;
+is_commutative('/=') -> true;
+is_commutative(_) -> false.
+
+def_used_1([#b_blk{is=Is,last=Last}|Bs], Preds, Def0, Used0) ->
+ {Def,Used1} = def_used_is(Is, Preds, Def0, Used0),
+ Used = ordsets:union(used(Last), Used1),
+ def_used_1(Bs, Preds, Def, Used);
+def_used_1([], _Preds, Def, Used) ->
+ {ordsets:from_list(Def),Used}.
+
+def_used_is([#b_set{op=phi,dst=Dst,args=Args}|Is],
+ Preds, Def0, Used0) ->
+ Def = [Dst|Def0],
+ %% We must be careful to only include variables that will
+ %% be used when arriving from one of the predecessor blocks
+ %% in Preds.
+ Used1 = [V || {#b_var{}=V,L} <- Args, cerl_sets:is_element(L, Preds)],
+ Used = ordsets:union(ordsets:from_list(Used1), Used0),
+ def_used_is(Is, Preds, Def, Used);
+def_used_is([#b_set{dst=Dst}=I|Is], Preds, Def0, Used0) ->
+ Def = [Dst|Def0],
+ Used = ordsets:union(used(I), Used0),
+ def_used_is(Is, Preds, Def, Used);
+def_used_is([], _Preds, Def, Used) ->
+ {Def,Used}.
+
+def_1([#b_blk{is=Is}|Bs], Def0) ->
+ Def = def_is(Is, Def0),
+ def_1(Bs, Def);
+def_1([], Def) ->
+ ordsets:from_list(Def).
+
+def_is([#b_set{dst=Dst}|Is], Def) ->
+ def_is(Is, [Dst|Def]);
+def_is([], Def) -> Def.
+
+dominators_1([{L,Preds}|Ls], Df, Doms) ->
+ DomPreds = [map_get(P, Doms) || P <- Preds, is_map_key(P, Doms)],
+ Dom = [L|dom_intersection(DomPreds, Df)],
+ dominators_1(Ls, Df, Doms#{L=>Dom});
+dominators_1([], _Df, Doms) -> Doms.
+
+dom_intersection([S], _Df) ->
+ S;
+dom_intersection([S|Ss], Df) ->
+ dom_intersection(S, Ss, Df).
+
+dom_intersection(S1, [S2|Ss], Df) ->
+ dom_intersection(dom_intersection_1(S1, S2, Df), Ss, Df);
+dom_intersection(S, [], _Df) -> S.
+
+dom_intersection_1([E1|Es1]=Set1, [E2|Es2]=Set2, Df) ->
+ %% Blocks are numbered in the order they are found in
+ %% reverse postorder.
+ #{E1:=Df1,E2:=Df2} = Df,
+ if Df1 > Df2 ->
+ dom_intersection_1(Es1, Set2, Df);
+ Df2 > Df1 ->
+ dom_intersection_1(Es2, Set1, Df); %switch arguments!
+ true -> %Set1 == Set2
+ %% The common suffix of the sets is the intersection.
+ Set1
+ end.
+
+number([L|Ls], N) ->
+ [{L,N}|number(Ls, N+1)];
+number([], _) -> [].
+
+fold_rpo_1([L|Ls], Fun, Blocks, Acc0) ->
+ Block = map_get(L, Blocks),
+ Acc = Fun(L, Block, Acc0),
+ fold_rpo_1(Ls, Fun, Blocks, Acc);
+fold_rpo_1([], _, _, Acc) -> Acc.
+
+fold_instrs_rpo_1([L|Ls], Fun, Blocks, Acc0) ->
+ #b_blk{is=Is,last=Last} = map_get(L, Blocks),
+ Acc1 = foldl(Fun, Acc0, Is),
+ Acc = Fun(Last, Acc1),
+ fold_instrs_rpo_1(Ls, Fun, Blocks, Acc);
+fold_instrs_rpo_1([], _, _, Acc) -> Acc.
+
+mapfold_instrs_rpo_1([L|Ls], Fun, Blocks0, Acc0) ->
+ #b_blk{is=Is0,last=Last0} = Block0 = map_get(L, Blocks0),
+ {Is,Acc1} = mapfoldl(Fun, Acc0, Is0),
+ {Last,Acc} = Fun(Last0, Acc1),
+ Block = Block0#b_blk{is=Is,last=Last},
+ Blocks = Blocks0#{L:=Block},
+ mapfold_instrs_rpo_1(Ls, Fun, Blocks, Acc);
+mapfold_instrs_rpo_1([], _, Blocks, Acc) ->
+ {Blocks,Acc}.
+
+flatmapfold_instrs_rpo_1([L|Ls], Fun, Blocks0, Acc0) ->
+ #b_blk{is=Is0,last=Last0} = Block0 = map_get(L, Blocks0),
+ {Is,Acc1} = flatmapfoldl(Fun, Acc0, Is0),
+ {[Last],Acc} = Fun(Last0, Acc1),
+ Block = Block0#b_blk{is=Is,last=Last},
+ Blocks = Blocks0#{L:=Block},
+ flatmapfold_instrs_rpo_1(Ls, Fun, Blocks, Acc);
+flatmapfold_instrs_rpo_1([], _, Blocks, Acc) ->
+ {Blocks,Acc}.
+
+linearize_1([L|Ls], Blocks, Seen0, Acc0) ->
+ case cerl_sets:is_element(L, Seen0) of
+ true ->
+ linearize_1(Ls, Blocks, Seen0, Acc0);
+ false ->
+ Seen1 = cerl_sets:add_element(L, Seen0),
+ Block = map_get(L, Blocks),
+ Successors = successors(Block),
+ {Acc,Seen} = linearize_1(Successors, Blocks, Seen1, Acc0),
+ linearize_1(Ls, Blocks, Seen, [{L,Block}|Acc])
+ end;
+linearize_1([], _, Seen, Acc) ->
+ {Acc,Seen}.
+
+fix_phis([{L,Blk0}|Bs], S) ->
+ Blk = case Blk0 of
+ #b_blk{is=[#b_set{op=phi}|_]=Is0} ->
+ Is = fix_phis_1(Is0, L, S),
+ Blk0#b_blk{is=Is};
+ #b_blk{} ->
+ Blk0
+ end,
+ Successors = successors(Blk),
+ [{L,Blk}|fix_phis(Bs, S#{L=>Successors})];
+fix_phis([], _) -> [].
+
+fix_phis_1([#b_set{op=phi,args=Args0}=I|Is], L, S) ->
+ Args = [{Val,Pred} || {Val,Pred} <- Args0,
+ is_successor(L, Pred, S)],
+ [I#b_set{args=Args}|fix_phis_1(Is, L, S)];
+fix_phis_1(Is, _, _) -> Is.
+
+is_successor(L, Pred, S) ->
+ case S of
+ #{Pred:=Successors} ->
+ member(L, Successors);
+ #{} ->
+ %% This block has been removed.
+ false
+ end.
+
+rpo_1([L|Ls], Blocks, Seen0, Acc0) ->
+ case cerl_sets:is_element(L, Seen0) of
+ true ->
+ rpo_1(Ls, Blocks, Seen0, Acc0);
+ false ->
+ Block = map_get(L, Blocks),
+ Seen1 = cerl_sets:add_element(L, Seen0),
+ Successors = successors(Block),
+ {Acc,Seen} = rpo_1(Successors, Blocks, Seen1, Acc0),
+ rpo_1(Ls, Blocks, Seen, [L|Acc])
+ end;
+rpo_1([], _, Seen, Acc) ->
+ {Acc,Seen}.
+
+rename_var(#b_var{}=Old, Rename) ->
+ case Rename of
+ #{Old:=New} -> New;
+ #{} -> Old
+ end;
+rename_var(#b_remote{mod=Mod0,name=Name0}=Remote, Rename) ->
+ Mod = rename_var(Mod0, Rename),
+ Name = rename_var(Name0, Rename),
+ Remote#b_remote{mod=Mod,name=Name};
+rename_var(Old, _) -> Old.
+
+rename_phi_vars([{Var,L}|As], Preds, Ren) ->
+ case cerl_sets:is_element(L, Preds) of
+ true ->
+ [{rename_var(Var, Ren),L}|rename_phi_vars(As, Preds, Ren)];
+ false ->
+ [{Var,L}|rename_phi_vars(As, Preds, Ren)]
+ end;
+rename_phi_vars([], _, _) -> [].
+
+map_instrs_1([L|Ls], Fun, Blocks0) ->
+ #b_blk{is=Is0,last=Last0} = Blk0 = map_get(L, Blocks0),
+ Is = [Fun(I) || I <- Is0],
+ Last = Fun(Last0),
+ Blk = Blk0#b_blk{is=Is,last=Last},
+ Blocks = Blocks0#{L:=Blk},
+ map_instrs_1(Ls, Fun, Blocks);
+map_instrs_1([], _, Blocks) -> Blocks.
+
+flatmapfoldl(F, Accu0, [Hd|Tail]) ->
+ {R,Accu1} = F(Hd, Accu0),
+ {Rs,Accu2} = flatmapfoldl(F, Accu1, Tail),
+ {R++Rs,Accu2};
+flatmapfoldl(_, Accu, []) -> {[],Accu}.
+
+split_blocks_1([L|Ls], P, Blocks0, Count0) ->
+ #b_blk{is=Is0} = Blk = map_get(L, Blocks0),
+ case split_blocks_is(Is0, P, []) of
+ {yes,Bef,Aft} ->
+ NewLbl = Count0,
+ Count = Count0 + 1,
+ Br = #b_br{bool=#b_literal{val=true},succ=NewLbl,fail=NewLbl},
+ BefBlk = Blk#b_blk{is=Bef,last=Br},
+ NewBlk = Blk#b_blk{is=Aft},
+ Blocks1 = Blocks0#{L:=BefBlk,NewLbl=>NewBlk},
+ Successors = successors(NewBlk),
+ Blocks = update_phi_labels(Successors, L, NewLbl, Blocks1),
+ split_blocks_1([NewLbl|Ls], P, Blocks, Count);
+ no ->
+ split_blocks_1(Ls, P, Blocks0, Count0)
+ end;
+split_blocks_1([], _, Blocks, Count) ->
+ {Blocks,Count}.
+
+split_blocks_is([I|Is], P, []) ->
+ split_blocks_is(Is, P, [I]);
+split_blocks_is([I|Is], P, Acc) ->
+ case P(I) of
+ true ->
+ {yes,reverse(Acc),[I|Is]};
+ false ->
+ split_blocks_is(Is, P, [I|Acc])
+ end;
+split_blocks_is([], _, _) -> no.
+
+update_phi_labels_is([#b_set{op=phi,args=Args0}=I0|Is], Old, New) ->
+ Args = [{Arg,rename_label(Lbl, Old, New)} || {Arg,Lbl} <- Args0],
+ I = I0#b_set{args=Args},
+ [I|update_phi_labels_is(Is, Old, New)];
+update_phi_labels_is(Is, _, _) -> Is.
+
+rename_label(Old, Old, New) -> New;
+rename_label(Lbl, _Old, _New) -> Lbl.
+
+used_args([#b_var{}=V|As]) ->
+ [V|used_args(As)];
+used_args([#b_remote{mod=Mod,name=Name}|As]) ->
+ used_args([Mod,Name|As]);
+used_args([_|As]) ->
+ used_args(As);
+used_args([]) -> [].
+
+used_1([H|T], Used0) ->
+ Used = ordsets:union(used(H), Used0),
+ used_1(T, Used);
+used_1([], Used) -> Used.