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authorJohn Högberg <[email protected]>2019-04-26 15:31:39 +0200
committerJohn Högberg <[email protected]>2019-04-29 11:20:41 +0200
commit65189902618e01e64326404fae9b1e63ff87b536 (patch)
tree06532d7914069ebbbb8d700d8d1391143ea2c3aa /lib
parent90eb43d0b61b5a51aede0537e394bd02216b6fa0 (diff)
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compiler: Propagate match context position on fail path
Diffstat (limited to 'lib')
-rw-r--r--lib/compiler/src/beam_ssa_pre_codegen.erl141
-rw-r--r--lib/compiler/test/bs_match_SUITE.erl35
2 files changed, 108 insertions, 68 deletions
diff --git a/lib/compiler/src/beam_ssa_pre_codegen.erl b/lib/compiler/src/beam_ssa_pre_codegen.erl
index bad43a9c4e..bf99e8fc26 100644
--- a/lib/compiler/src/beam_ssa_pre_codegen.erl
+++ b/lib/compiler/src/beam_ssa_pre_codegen.erl
@@ -342,21 +342,22 @@ make_save_point_dict_1([], Ctx, I, Acc) ->
[{Ctx,I}|Acc].
bs_restores([{L,#b_blk{is=Is,last=Last}}|Bs], CtxChain, D0, Rs0) ->
- FPos = case D0 of
- #{L:=Pos0} -> Pos0;
- #{} -> #{}
- end,
- {SPos,Rs} = bs_restores_is(Is, CtxChain, FPos, Rs0),
- D = bs_update_successors(Last, SPos, FPos, D0),
+ InPos = maps:get(L, D0, #{}),
+ {SuccPos, FailPos, Rs} = bs_restores_is(Is, CtxChain, InPos, InPos, Rs0),
+
+ D = bs_update_successors(Last, SuccPos, FailPos, D0),
bs_restores(Bs, CtxChain, D, Rs);
bs_restores([], _, _, Rs) -> Rs.
bs_update_successors(#b_br{succ=Succ,fail=Fail}, SPos, FPos, D) ->
join_positions([{Succ,SPos},{Fail,FPos}], D);
-bs_update_successors(#b_switch{fail=Fail,list=List}, SPos, _FPos, D) ->
+bs_update_successors(#b_switch{fail=Fail,list=List}, SPos, FPos, D) ->
+ SPos = FPos, %Assertion.
Update = [{L,SPos} || {_,L} <- List] ++ [{Fail,SPos}],
join_positions(Update, D);
-bs_update_successors(#b_ret{}, _, _, D) -> D.
+bs_update_successors(#b_ret{}, SPos, FPos, D) ->
+ SPos = FPos, %Assertion.
+ D.
join_positions([{L,MapPos0}|T], D) ->
case D of
@@ -382,75 +383,91 @@ join_positions_1(MapPos0, MapPos1) ->
end, MapPos1),
maps:merge(MapPos0, MapPos2).
+%%
+%% Updates the restore and position maps according to the given instructions.
+%%
+%% Note that positions may be updated even when a match fails; if a match
+%% requires a restore, the position at the fail block will be the position
+%% we've *restored to* and not the one we entered the current block with.
+%%
+
bs_restores_is([#b_set{op=bs_start_match,dst=Start}|Is],
- CtxChain, PosMap0, Rs) ->
- PosMap = PosMap0#{Start=>Start},
- bs_restores_is(Is, CtxChain, PosMap, Rs);
+ CtxChain, SPos0, FPos, Rs) ->
+ %% We only allow one match per block.
+ SPos0 = FPos, %Assertion.
+ SPos = SPos0#{Start=>Start},
+ bs_restores_is(Is, CtxChain, SPos, FPos, Rs);
bs_restores_is([#b_set{op=bs_match,dst=NewPos,args=Args}=I|Is],
- CtxChain, PosMap0, Rs0) ->
+ CtxChain, SPos0, FPos0, Rs0) ->
+ SPos0 = FPos0, %Assertion.
Start = bs_subst_ctx(NewPos, CtxChain),
[_,FromPos|_] = Args,
- case PosMap0 of
+ case SPos0 of
#{Start:=FromPos} ->
%% Same position, no restore needed.
- PosMap = case bs_match_type(I) of
+ SPos = case bs_match_type(I) of
plain ->
%% Update position to new position.
- PosMap0#{Start:=NewPos};
+ SPos0#{Start:=NewPos};
_ ->
%% Position will not change (test_unit
%% instruction or no instruction at
%% all).
- PosMap0#{Start:=FromPos}
+ SPos0#{Start:=FromPos}
end,
- bs_restores_is(Is, CtxChain, PosMap, Rs0);
+ bs_restores_is(Is, CtxChain, SPos, FPos0, Rs0);
#{Start:=_} ->
%% Different positions, might need a restore instruction.
case bs_match_type(I) of
none ->
- %% The tail test will be optimized away.
- %% No need to do a restore.
- PosMap = PosMap0#{Start:=FromPos},
- bs_restores_is(Is, CtxChain, PosMap, Rs0);
+ %% This is a tail test that will be optimized away.
+ %% There's no need to do a restore, and all
+ %% positions are unchanged.
+ bs_restores_is(Is, CtxChain, SPos0, FPos0, Rs0);
test_unit ->
%% This match instruction will be replaced by
%% a test_unit instruction. We will need a
%% restore. The new position will be the position
%% restored to (NOT NewPos).
- PosMap = PosMap0#{Start:=FromPos},
+ SPos = SPos0#{Start:=FromPos},
+ FPos = FPos0#{Start:=FromPos},
Rs = Rs0#{NewPos=>{Start,FromPos}},
- bs_restores_is(Is, CtxChain, PosMap, Rs);
+ bs_restores_is(Is, CtxChain, SPos, FPos, Rs);
plain ->
%% Match or skip. Position will be changed.
- PosMap = PosMap0#{Start:=NewPos},
+ SPos = SPos0#{Start:=NewPos},
+ FPos = FPos0#{Start:=FromPos},
Rs = Rs0#{NewPos=>{Start,FromPos}},
- bs_restores_is(Is, CtxChain, PosMap, Rs)
+ bs_restores_is(Is, CtxChain, SPos, FPos, Rs)
end
end;
bs_restores_is([#b_set{op=bs_extract,args=[FromPos|_]}|Is],
- CtxChain, PosMap, Rs) ->
+ CtxChain, SPos, FPos, Rs) ->
Start = bs_subst_ctx(FromPos, CtxChain),
- #{Start:=FromPos} = PosMap, %Assertion.
- bs_restores_is(Is, CtxChain, PosMap, Rs);
+ #{Start:=FromPos} = SPos, %Assertion.
+ #{Start:=FromPos} = FPos, %Assertion.
+ bs_restores_is(Is, CtxChain, SPos, FPos, Rs);
bs_restores_is([#b_set{op=call,dst=Dst,args=Args}|Is],
- CtxChain, PosMap0, Rs0) ->
- {Rs,PosMap1} = bs_restore_args(Args, PosMap0, CtxChain, Dst, Rs0),
- PosMap = bs_invalidate_pos(Args, PosMap1, CtxChain),
- bs_restores_is(Is, CtxChain, PosMap, Rs);
-bs_restores_is([#b_set{op=landingpad}|Is], CtxChain, PosMap0, Rs) ->
+ CtxChain, SPos0, FPos0, Rs0) ->
+ {Rs, SPos1, FPos1} = bs_restore_args(Args, SPos0, FPos0, CtxChain, Dst, Rs0),
+ {SPos, FPos} = bs_invalidate_pos(Args, SPos1, FPos1, CtxChain),
+ bs_restores_is(Is, CtxChain, SPos, FPos, Rs);
+bs_restores_is([#b_set{op=landingpad}|Is], CtxChain, SPos0, FPos0, Rs) ->
%% We can land here from any point, so all positions are invalid.
- PosMap = maps:map(fun(_Start,_Pos) -> unknown end, PosMap0),
- bs_restores_is(Is, CtxChain, PosMap, Rs);
+ Invalidate = fun(_Start,_Pos) -> unknown end,
+ SPos = maps:map(Invalidate, SPos0),
+ FPos = maps:map(Invalidate, FPos0),
+ bs_restores_is(Is, CtxChain, SPos, FPos, Rs);
bs_restores_is([#b_set{op=Op,dst=Dst,args=Args}|Is],
- CtxChain, PosMap0, Rs0)
+ CtxChain, SPos0, FPos0, Rs0)
when Op =:= bs_test_tail;
Op =:= bs_get_tail ->
- {Rs,PosMap} = bs_restore_args(Args, PosMap0, CtxChain, Dst, Rs0),
- bs_restores_is(Is, CtxChain, PosMap, Rs);
-bs_restores_is([_|Is], CtxChain, PosMap, Rs) ->
- bs_restores_is(Is, CtxChain, PosMap, Rs);
-bs_restores_is([], _CtxChain, PosMap, Rs) ->
- {PosMap,Rs}.
+ {Rs, SPos, FPos} = bs_restore_args(Args, SPos0, FPos0, CtxChain, Dst, Rs0),
+ bs_restores_is(Is, CtxChain, SPos, FPos, Rs);
+bs_restores_is([_|Is], CtxChain, SPos, FPos, Rs) ->
+ bs_restores_is(Is, CtxChain, SPos, FPos, Rs);
+bs_restores_is([], _CtxChain, SPos, FPos, Rs) ->
+ {SPos, FPos, Rs}.
bs_match_type(#b_set{args=[#b_literal{val=skip},_Ctx,
#b_literal{val=binary},_Flags,
@@ -464,40 +481,42 @@ bs_match_type(_) ->
%% Call instructions leave the match position in an undefined state,
%% requiring us to invalidate each affected argument.
-bs_invalidate_pos([#b_var{}=Arg|Args], PosMap0, CtxChain) ->
+bs_invalidate_pos([#b_var{}=Arg|Args], SPos0, FPos0, CtxChain) ->
Start = bs_subst_ctx(Arg, CtxChain),
- case PosMap0 of
+ case SPos0 of
#{Start:=_} ->
- PosMap = PosMap0#{Start:=unknown},
- bs_invalidate_pos(Args, PosMap, CtxChain);
+ SPos = SPos0#{Start:=unknown},
+ FPos = FPos0#{Start:=unknown},
+ bs_invalidate_pos(Args, SPos, FPos, CtxChain);
#{} ->
%% Not a match context.
- bs_invalidate_pos(Args, PosMap0, CtxChain)
+ bs_invalidate_pos(Args, SPos0, FPos0, CtxChain)
end;
-bs_invalidate_pos([_|Args], PosMap, CtxChain) ->
- bs_invalidate_pos(Args, PosMap, CtxChain);
-bs_invalidate_pos([], PosMap, _CtxChain) ->
- PosMap.
+bs_invalidate_pos([_|Args], SPos, FPos, CtxChain) ->
+ bs_invalidate_pos(Args, SPos, FPos, CtxChain);
+bs_invalidate_pos([], SPos, FPos, _CtxChain) ->
+ {SPos, FPos}.
-bs_restore_args([#b_var{}=Arg|Args], PosMap0, CtxChain, Dst, Rs0) ->
+bs_restore_args([#b_var{}=Arg|Args], SPos0, FPos0, CtxChain, Dst, Rs0) ->
Start = bs_subst_ctx(Arg, CtxChain),
- case PosMap0 of
+ case SPos0 of
#{Start:=Arg} ->
%% Same position, no restore needed.
- bs_restore_args(Args, PosMap0, CtxChain, Dst, Rs0);
+ bs_restore_args(Args, SPos0, FPos0, CtxChain, Dst, Rs0);
#{Start:=_} ->
%% Different positions, need a restore instruction.
- PosMap = PosMap0#{Start:=Arg},
+ SPos = SPos0#{Start:=Arg},
+ FPos = FPos0#{Start:=Arg},
Rs = Rs0#{Dst=>{Start,Arg}},
- bs_restore_args(Args, PosMap, CtxChain, Dst, Rs);
+ bs_restore_args(Args, SPos, FPos, CtxChain, Dst, Rs);
#{} ->
%% Not a match context.
- bs_restore_args(Args, PosMap0, CtxChain, Dst, Rs0)
+ bs_restore_args(Args, SPos0, FPos0, CtxChain, Dst, Rs0)
end;
-bs_restore_args([_|Args], PosMap, CtxChain, Dst, Rs) ->
- bs_restore_args(Args, PosMap, CtxChain, Dst, Rs);
-bs_restore_args([], PosMap, _CtxChain, _Dst, Rs) ->
- {Rs,PosMap}.
+bs_restore_args([_|Args], SPos, FPos, CtxChain, Dst, Rs) ->
+ bs_restore_args(Args, SPos, FPos, CtxChain, Dst, Rs);
+bs_restore_args([], SPos, FPos, _CtxChain, _Dst, Rs) ->
+ {Rs,SPos,FPos}.
%% Insert all bs_save and bs_restore instructions.
diff --git a/lib/compiler/test/bs_match_SUITE.erl b/lib/compiler/test/bs_match_SUITE.erl
index 41e4918b1e..d97f49c56e 100644
--- a/lib/compiler/test/bs_match_SUITE.erl
+++ b/lib/compiler/test/bs_match_SUITE.erl
@@ -1891,15 +1891,37 @@ expression_before_match_1(R) ->
%% Make sure that context positions are updated on calls.
restore_on_call(Config) when is_list(Config) ->
- ok = restore_on_call_1(<<0, 1, 2>>).
+ ok = restore_on_call_plain(<<0, 1, 2>>),
+ <<"x">> = restore_on_call_match(<<0, "x">>),
+ ok.
-restore_on_call_1(<<0, Rest/binary>>) ->
- <<2>> = restore_on_call_2(Rest),
- <<2>> = restore_on_call_2(Rest), %% {badmatch, <<>>} on missing restore.
+restore_on_call_plain(<<0, Rest/binary>>) ->
+ <<2>> = restore_on_call_plain_1(Rest),
+ %% {badmatch, <<>>} on missing restore.
+ <<2>> = restore_on_call_plain_1(Rest),
ok.
-restore_on_call_2(<<1, Rest/binary>>) -> Rest;
-restore_on_call_2(Other) -> Other.
+restore_on_call_plain_1(<<1, Rest/binary>>) -> Rest;
+restore_on_call_plain_1(Other) -> Other.
+
+%% Calls a function that moves the match context passed to it, and then matches
+%% on its result to confuse the reposition algorithm's success/fail logic.
+restore_on_call_match(<<0, Bin/binary>>) ->
+ case skip_until_zero(Bin) of
+ {skipped, Rest} ->
+ Rest;
+ not_found ->
+ %% The match context did not get repositioned before the
+ %% bs_get_tail instruction here.
+ Bin
+ end.
+
+skip_until_zero(<<0,Rest/binary>>) ->
+ {skipped, Rest};
+skip_until_zero(<<_C,Rest/binary>>) ->
+ skip_until_zero(Rest);
+skip_until_zero(_) ->
+ not_found.
%% 'catch' must invalidate positions.
restore_after_catch(Config) when is_list(Config) ->
@@ -1983,5 +2005,4 @@ do_matching_meets_apply(_Bin, {Handler, State}) ->
%% Another case of the above.
Handler:abs(State).
-
id(I) -> I.