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Fix two type-related bugs
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Issue erlang#7147 uncovered two bugs in the compiler.

The first one is in the swapping of operands for commutative operands,
which the compiler does to simplify for the JIT. When the operands
were swapped, types for the operands in the annotation were not
updated.

The second one is in `beam_validator`, which assumed that if the
binary construction `<<F/float>>` succeeded, then `F` must be a
float. That is not correct, because `F` could also be an integer.

Closes erlang#7147
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bjorng committed Apr 25, 2023
1 parent 98e3bf2 commit b178b93
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Showing 4 changed files with 108 additions and 5 deletions.
15 changes: 13 additions & 2 deletions lib/compiler/src/beam_ssa.erl
Original file line number Diff line number Diff line change
Expand Up @@ -383,10 +383,21 @@ successors(#b_blk{last=Terminator}) ->
-spec normalize(b_set() | terminator()) ->
b_set() | terminator().

normalize(#b_set{op={bif,Bif},args=Args}=Set) ->
normalize(#b_set{anno=Anno0,op={bif,Bif},args=Args}=Set) ->
case {is_commutative(Bif),Args} of
{true, [#b_literal{}=Lit,#b_var{}=Var]} ->
Set#b_set{args=[Var,Lit]};
Anno = case Anno0 of
#{arg_types := ArgTypes0} ->
case ArgTypes0 of
#{1 := Type} ->
Anno0#{arg_types => #{0 => Type}};
#{} ->
Anno0
end;
#{} ->
Anno0
end,
Set#b_set{anno=Anno,args=[Var,Lit]};
{_, _} ->
Set
end;
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2 changes: 1 addition & 1 deletion lib/compiler/src/beam_validator.erl
Original file line number Diff line number Diff line change
Expand Up @@ -1582,7 +1582,7 @@ update_create_bin_list([], Vst) -> Vst.
update_create_bin_type(append) -> #t_bitstring{};
update_create_bin_type(private_append) -> #t_bitstring{};
update_create_bin_type(binary) -> #t_bitstring{};
update_create_bin_type(float) -> #t_float{};
update_create_bin_type(float) -> #t_number{};
update_create_bin_type(integer) -> #t_integer{};
update_create_bin_type(utf8) -> #t_integer{};
update_create_bin_type(utf16) -> #t_integer{};
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90 changes: 88 additions & 2 deletions lib/compiler/test/beam_ssa_SUITE.erl
Original file line number Diff line number Diff line change
Expand Up @@ -27,7 +27,7 @@
beam_ssa_dead_crash/1,stack_init/1,
mapfoldl/0,mapfoldl/1,
grab_bag/1,redundant_br/1,
coverage/1]).
coverage/1,normalize/1]).

suite() -> [{ct_hooks,[ts_install_cth]}].

Expand All @@ -48,7 +48,8 @@ groups() ->
stack_init,
grab_bag,
redundant_br,
coverage
coverage,
normalize
]}].

init_per_suite(Config) ->
Expand Down Expand Up @@ -1260,5 +1261,90 @@ coverage_5() ->
error
end#coverage{name = whatever}.

%% Test beam_ssa:normalize/1, especially that argument types are
%% correctly updated when arguments are swapped.
normalize(_Config) ->
normalize_commutative({bif,'band'}),
normalize_commutative({bif,'+'}),

normalize_noncommutative({bif,'div'}),

ok.

-record(b_var, {name}).
-record(b_literal, {val}).

normalize_commutative(Op) ->
A = #b_var{name=a},
B = #b_var{name=b},
Lit = #b_literal{val=42},

normalize_same(Op, [A,B]),
normalize_same(Op, [A,Lit]),

normalize_swapped(Op, [Lit,A]),

ok.

normalize_noncommutative(Op) ->
A = #b_var{name=a},
B = #b_var{name=b},
Lit = #b_literal{val=42},

normalize_same(Op, [A,B]),
normalize_same(Op, [A,Lit]),

ArgTypes0 = [{1,beam_types:make_integer(0, 1023)}],
I1 = make_bset(ArgTypes0, Op, [Lit,A]),
I1 = beam_ssa:normalize(I1),

ok.

normalize_same(Op, Args) ->
I0 = make_bset(#{}, Op, Args),
I0 = beam_ssa:normalize(I0),

ArgTypes0 = [{0,beam_types:make_integer(0, 1023)}],
I1 = make_bset(ArgTypes0, Op, Args),
I1 = beam_ssa:normalize(I1),

case Args of
[#b_var{},#b_var{}] ->
ArgTypes1 = [{0,beam_types:make_integer(0, 1023)},
{1,beam_types:make_integer(42)}],
I2 = make_bset(ArgTypes1, Op, Args),
I2 = beam_ssa:normalize(I2);
[_,_] ->
ok
end,

ok.

normalize_swapped(Op, [#b_literal{}=Lit,#b_var{}=Var]=Args) ->
EmptyAnno = #{},
I0 = make_bset(EmptyAnno, Op, Args),
{b_set,EmptyAnno,#b_var{name=1000},Op,[Var,Lit]} = beam_ssa:normalize(I0),

EmptyTypes = #{arg_types => #{}},
I1 = make_bset(EmptyTypes, Op, Args),
{b_set,EmptyTypes,#b_var{name=1000},Op,[Var,Lit]} = beam_ssa:normalize(I1),

IntRange = beam_types:make_integer(0, 1023),
ArgTypes0 = [{1,IntRange}],
I2 = make_bset(ArgTypes0, Op, Args),
{[{0,IntRange}],Op,[Var,Lit]} = unpack_bset(beam_ssa:normalize(I2)),

ok.

make_bset(ArgTypes, Op, Args) when is_list(ArgTypes) ->
Anno = #{arg_types => maps:from_list(ArgTypes)},
{b_set,Anno,#b_var{name=1000},Op,Args};
make_bset(Anno, Op, Args) when is_map(Anno) ->
{b_set,Anno,#b_var{name=1000},Op,Args}.

unpack_bset({b_set,Anno,{b_var,1000},Op,Args}) ->
ArgTypes = maps:get(arg_types, Anno, #{}),
{lists:sort(maps:to_list(ArgTypes)),Op,Args}.

%% The identity function.
id(I) -> I.
6 changes: 6 additions & 0 deletions lib/compiler/test/beam_type_SUITE.erl
Original file line number Diff line number Diff line change
Expand Up @@ -741,11 +741,17 @@ record_float(R, N0) ->

binary_float(_Config) ->
<<-1/float>> = binary_negate_float(<<1/float>>),
{'EXIT',{badarg,_}} = catch binary_float_1(id(64.0), id(0)),
ok.

binary_negate_float(<<Float/float>>) ->
<<-Float/float>>.

%% GH-7147.
binary_float_1(X, Y) ->
_ = <<Y:(ceil(64.0 = X))/float, (binary_to_integer(ok))>>,
ceil(X) band Y.

float_compare(_Config) ->
false = do_float_compare(-42.0),
false = do_float_compare(-42),
Expand Down

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