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authorBjörn Gustavsson <[email protected]>2016-09-26 15:01:19 +0200
committerBjörn Gustavsson <[email protected]>2016-10-05 13:00:45 +0200
commit0c599bcad1e7f5f66dd2342ab27791048145e892 (patch)
tree2f9702b3f3c829d6862df0cc193d5abc394251b4 /lib
parent3f3f25b23379b1afb15cc97462cf5d385690f5a0 (diff)
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beam_block: Avoid unsafe inclusion of get_map_elements in blocks
c2035ebb8b restricted the get_map_elements instruction so that it could only occur at the beginning of a block. It turns out that including it anywhere in a block is unsafe. Therefore, never put get_map_elements instruction in blocks. (Also remove the beam_utils:join_even/2 function since it is no longer used.) ERL-266
Diffstat (limited to 'lib')
-rw-r--r--lib/compiler/src/beam_block.erl10
-rw-r--r--lib/compiler/src/beam_flatten.erl1
-rw-r--r--lib/compiler/src/beam_split.erl3
-rw-r--r--lib/compiler/src/beam_utils.erl12
-rw-r--r--lib/compiler/test/beam_block_SUITE.erl26
5 files changed, 30 insertions, 22 deletions
diff --git a/lib/compiler/src/beam_block.erl b/lib/compiler/src/beam_block.erl
index ec41925beb..6a35191f6e 100644
--- a/lib/compiler/src/beam_block.erl
+++ b/lib/compiler/src/beam_block.erl
@@ -58,13 +58,6 @@ blockify(Is) ->
blockify([{loop_rec,{f,Fail},{x,0}},{loop_rec_end,_Lbl},{label,Fail}|Is], Acc) ->
%% Useless instruction sequence.
blockify(Is, Acc);
-blockify([{get_map_elements,F,S,{list,Gets}}|Is0], Acc) ->
- %% A get_map_elements instruction is only safe at the beginning of
- %% a block because of the failure label.
- {Ss,Ds} = beam_utils:split_even(Gets),
- I = {set,Ds,[S|Ss],{get_map_elements,F}},
- {Block,Is} = collect_block(Is0, [I]),
- blockify(Is, [{block,Block}|Acc]);
blockify([I|Is0]=IsAll, Acc) ->
case collect(I) of
error -> blockify(Is0, [I|Acc]);
@@ -220,7 +213,6 @@ move_allocates_1([], Acc) -> Acc.
alloc_may_pass({set,_,_,{alloc,_,_}}) -> false;
alloc_may_pass({set,_,_,{set_tuple_element,_}}) -> false;
-alloc_may_pass({set,_,_,{get_map_elements,_}}) -> false;
alloc_may_pass({set,_,_,put_list}) -> false;
alloc_may_pass({set,_,_,put}) -> false;
alloc_may_pass({set,_,_,_}) -> true.
@@ -235,8 +227,6 @@ opt([{set,_,_,{line,_}}=Line1,
{set,[D2],[{integer,Idx2},Reg],{bif,element,{f,0}}}=I2|Is])
when Idx1 < Idx2, D1 =/= D2, D1 =/= Reg, D2 =/= Reg ->
opt([Line2,I2,Line1,I1|Is]);
-opt([{set,[_|_],_Ss,{get_map_elements,_F}}=I|Is]) ->
- [I|opt(Is)];
opt([{set,Ds0,Ss,Op}|Is0]) ->
{Ds,Is} = opt_moves(Ds0, Is0),
[{set,Ds,Ss,Op}|opt(Is)];
diff --git a/lib/compiler/src/beam_flatten.erl b/lib/compiler/src/beam_flatten.erl
index 36369bd0b4..c9ff07b496 100644
--- a/lib/compiler/src/beam_flatten.erl
+++ b/lib/compiler/src/beam_flatten.erl
@@ -64,7 +64,6 @@ norm({set,[],[S,D],{set_tuple_element,I}}) -> {set_tuple_element,S,D,I};
norm({set,[D1,D2],[S],get_list}) -> {get_list,S,D1,D2};
norm({set,[D],[S|Puts],{alloc,R,{put_map,Op,F}}}) ->
{put_map,F,Op,S,D,R,{list,Puts}};
-%% get_map_elements is always handled in beam_split (moved out of block)
norm({set,[],[],remove_message}) -> remove_message;
norm({set,[],[],fclearerror}) -> fclearerror;
norm({set,[],[],fcheckerror}) -> {fcheckerror,{f,0}}.
diff --git a/lib/compiler/src/beam_split.erl b/lib/compiler/src/beam_split.erl
index c83c686953..feeab0af50 100644
--- a/lib/compiler/src/beam_split.erl
+++ b/lib/compiler/src/beam_split.erl
@@ -56,9 +56,6 @@ split_block([{set,[D],[S|Puts],{alloc,R,{put_map,Op,{f,Lbl}=Fail}}}|Is],
Bl, Acc) when Lbl =/= 0 ->
split_block(Is, [], [{put_map,Fail,Op,S,D,R,{list,Puts}}|
make_block(Bl, Acc)]);
-split_block([{set,Ds,[S|Ss],{get_map_elements,Fail}}|Is], Bl, Acc) ->
- Gets = beam_utils:join_even(Ss,Ds),
- split_block(Is, [], [{get_map_elements,Fail,S,{list,Gets}}|make_block(Bl, Acc)]);
split_block([{set,[R],[],{try_catch,Op,L}}|Is], Bl, Acc) ->
split_block(Is, [], [{Op,R,L}|make_block(Bl, Acc)]);
split_block([{set,[],[],{line,_}=Line}|Is], Bl, Acc) ->
diff --git a/lib/compiler/src/beam_utils.erl b/lib/compiler/src/beam_utils.erl
index a15ecf633e..249d9395ca 100644
--- a/lib/compiler/src/beam_utils.erl
+++ b/lib/compiler/src/beam_utils.erl
@@ -26,7 +26,7 @@
empty_label_index/0,index_label/3,index_labels/1,
code_at/2,bif_to_test/3,is_pure_test/1,
live_opt/1,delete_live_annos/1,combine_heap_needs/2,
- join_even/2,split_even/1]).
+ split_even/1]).
-import(lists, [member/2,sort/1,reverse/1,splitwith/2]).
@@ -233,11 +233,6 @@ combine_heap_needs(H1, H2) when is_integer(H1), is_integer(H2) ->
split_even(Rs) -> split_even(Rs, [], []).
-%% join_even/1
-%% {[1,3,5],[2,4,6]} -> [1,2,3,4,5,6]
-
-join_even([], []) -> [];
-join_even([S|Ss], [D|Ds]) -> [S,D|join_even(Ss, Ds)].
%%%
%%% Local functions.
@@ -753,6 +748,11 @@ live_opt([timeout=I|Is], _, D, Acc) ->
live_opt(Is, 0, D, [I|Acc]);
live_opt([{wait,_}=I|Is], _, D, Acc) ->
live_opt(Is, 0, D, [I|Acc]);
+live_opt([{get_map_elements,Fail,Src,{list,List}}=I|Is], Regs0, D, Acc) ->
+ {Ss,Ds} = split_even(List),
+ Regs1 = x_live([Src|Ss], x_dead(Ds, Regs0)),
+ Regs = live_join_label(Fail, D, Regs1),
+ live_opt(Is, Regs, D, [I|Acc]);
%% Transparent instructions - they neither use nor modify x registers.
live_opt([{deallocate,_}=I|Is], Regs, D, Acc) ->
diff --git a/lib/compiler/test/beam_block_SUITE.erl b/lib/compiler/test/beam_block_SUITE.erl
index 9fcb6e497d..55d5f2dbe8 100644
--- a/lib/compiler/test/beam_block_SUITE.erl
+++ b/lib/compiler/test/beam_block_SUITE.erl
@@ -22,7 +22,7 @@
-export([all/0,suite/0,groups/0,init_per_suite/1,end_per_suite/1,
init_per_group/2,end_per_group/2,
get_map_elements/1,otp_7345/1,move_opt_across_gc_bif/1,
- erl_202/1]).
+ erl_202/1,repro/1]).
%% The only test for the following functions is that
%% the code compiles and is accepted by beam_validator.
@@ -39,7 +39,8 @@ groups() ->
[get_map_elements,
otp_7345,
move_opt_across_gc_bif,
- erl_202
+ erl_202,
+ repro
]}].
init_per_suite(Config) ->
@@ -158,6 +159,27 @@ erl_202({{_, _},X}, _) ->
erl_202({_, _}, #erl_202_r1{y=R2}) ->
{R2#erl_202_r2.x}.
+%% See https://bugs.erlang.org/browse/ERL-266.
+%% Instructions with failure labels are not safe to include
+%% in a block. Including get_map_elements in a block would
+%% lead to unsafe code.
+
+repro(_Config) ->
+ [] = maps:to_list(repro([], #{}, #{})),
+ [{tmp1,n}] = maps:to_list(repro([{tmp1,0}], #{}, #{})),
+ [{tmp1,name}] = maps:to_list(repro([{tmp1,0}], #{}, #{0=>name})),
+ ok.
+
+repro([], TempNames, _Slots) ->
+ TempNames;
+repro([{Temp, Slot}|Xs], TempNames, Slots0) ->
+ {Name, Slots} =
+ case Slots0 of
+ #{Slot := Name0} -> {Name0, Slots0};
+ #{} -> {n, Slots0#{Slot => n}}
+ end,
+ repro(Xs, TempNames#{Temp => Name}, Slots).
+
%%%
%%% The only test of the following code is that it compiles.
%%%