%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2011-2018. 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%
%%
-module(beam_except).
-export([module/2]).
%%% Rewrite certain calls to erlang:error/{1,2} to specialized
%%% instructions:
%%%
%%% erlang:error({badmatch,Value}) => badmatch Value
%%% erlang:error({case_clause,Value}) => case_end Value
%%% erlang:error({try_clause,Value}) => try_case_end Value
%%% erlang:error(if_clause) => if_end
%%% erlang:error(function_clause, Args) => jump FuncInfoLabel
%%%
-import(lists, [reverse/1,reverse/2,seq/2,splitwith/2]).
-spec module(beam_utils:module_code(), [compile:option()]) ->
{'ok',beam_utils:module_code()}.
module({Mod,Exp,Attr,Fs0,Lc}, _Opt) ->
Fs = [function(F) || F <- Fs0],
{ok,{Mod,Exp,Attr,Fs,Lc}}.
function({function,Name,Arity,CLabel,Is0}) ->
try
Is = function_1(Is0),
{function,Name,Arity,CLabel,Is}
catch
Class:Error:Stack ->
io:fwrite("Function: ~w/~w\n", [Name,Arity]),
erlang:raise(Class, Error, Stack)
end.
-record(st,
{lbl :: beam_asm:label(), %func_info label
loc :: [_], %location for func_info
arity :: arity() %arity for function
}).
function_1(Is0) ->
case Is0 of
[{label,Lbl},{line,Loc},{func_info,_,_,Arity}|_] ->
St = #st{lbl=Lbl,loc=Loc,arity=Arity},
translate(Is0, St, []);
[{label,_}|_] ->
%% No line numbers. The source must be a .S file.
%% There is no need to do anything.
Is0
end.
translate([{call_ext,Ar,{extfunc,erlang,error,Ar}}=I|Is], St, Acc) ->
translate_1(Ar, I, Is, St, Acc);
translate([I|Is], St, Acc) ->
translate(Is, St, [I|Acc]);
translate([], _, Acc) ->
reverse(Acc).
translate_1(Ar, I, Is, #st{arity=Arity}=St, [{line,_}=Line|Acc1]=Acc0) ->
case dig_out(Ar, Arity, Acc1) of
no ->
translate(Is, St, [I|Acc0]);
{yes,function_clause,Acc2} ->
case {Is,Line,St} of
{[return|_],{line,Loc},#st{lbl=Fi,loc=Loc}} ->
Instr = {jump,{f,Fi}},
translate(Is, St, [Instr|Acc2]);
{_,_,_} ->
%% Not a call_only instruction, or not the same
%% location information as in in the line instruction
%% before the func_info instruction. Not safe
%% to translate to a jump.
translate(Is, St, [I|Acc0])
end;
{yes,Instr,Acc2} ->
translate(Is, St, [Instr,Line|Acc2])
end.
dig_out(1, _Arity, Is) ->
dig_out(Is);
dig_out(2, Arity, Is) ->
dig_out_fc(Arity, Is);
dig_out(_, _, _) -> no.
dig_out([{block,Bl0}|Is]) ->
case dig_out_block(reverse(Bl0)) of
no -> no;
{yes,What,[]} ->
{yes,What,Is};
{yes,What,Bl} ->
{yes,What,[{block,Bl}|Is]}
end;
dig_out(_) -> no.
dig_out_block([{set,[{x,0}],[{atom,if_clause}],move}]) ->
{yes,if_end,[]};
dig_out_block([{set,[{x,0}],[{literal,{Exc,Value}}],move}|Is]) ->
translate_exception(Exc, {literal,Value}, Is, 0);
dig_out_block([{set,[{x,0}],[{atom,Exc},Value],put_tuple2}|Is]) ->
translate_exception(Exc, Value, Is, 3);
dig_out_block(_) -> no.
translate_exception(badmatch, Val, Is, Words) ->
{yes,{badmatch,Val},fix_block(Is, Words)};
translate_exception(case_clause, Val, Is, Words) ->
{yes,{case_end,Val},fix_block(Is, Words)};
translate_exception(try_clause, Val, Is, Words) ->
{yes,{try_case_end,Val},fix_block(Is, Words)};
translate_exception(_, _, _, _) -> no.
fix_block(Is, 0) ->
reverse(Is);
fix_block(Is, Words) ->
reverse(fix_block_1(Is, Words)).
fix_block_1([{set,[],[],{alloc,Live,{F1,F2,Needed0,F3}}}|Is], Words) ->
case Needed0 - Words of
0 ->
Is;
Needed ->
true = Needed >= 0, %Assertion.
[{set,[],[],{alloc,Live,{F1,F2,Needed,F3}}}|Is]
end;
fix_block_1([I|Is], Words) ->
[I|fix_block_1(Is, Words)];
fix_block_1([], _Words) ->
%% Rare. The heap allocation was probably done by a binary
%% construction instruction.
[].
dig_out_fc(Arity, Is0) ->
Regs0 = maps:from_list([{{x,X},{arg,X}} || X <- seq(0, Arity-1)]),
{Is,Acc0} = splitwith(fun({label,_}) -> false;
({test,_,_,_}) -> false;
(_) -> true
end, Is0),
{Regs,Acc} = dig_out_fc_1(reverse(Is), Arity, Regs0, Acc0),
case Regs of
#{{x,0}:={atom,function_clause},{x,1}:=Args} ->
case moves_from_stack(Args, 0, []) of
{Moves,Arity} ->
{yes,function_clause,reverse(Moves, Acc)};
{_,_} ->
no
end;
#{} ->
no
end.
dig_out_fc_1([{block,Bl}|Is], Arity, Regs0, Acc) ->
Regs = dig_out_fc_block(Bl, Regs0),
dig_out_fc_1(Is, Arity, Regs, Acc);
dig_out_fc_1([{bs_set_position,_,_}=I|Is], Arity, Regs, Acc) ->
dig_out_fc_1(Is, Arity, Regs, [I|Acc]);
dig_out_fc_1([{bs_get_tail,Src,Dst,Live0}|Is], Arity, Regs0, Acc) ->
case Src of
{x,X} when X < Arity ->
%% The heuristic for determining the number of live
%% registers is likely to give an incorrect result.
%% Give up.
{#{},[]};
_ ->
Regs = prune_xregs(Live0, Regs0),
Live = dig_out_stack_live(Regs, Live0),
I = {bs_get_tail,Src,Dst,Live},
dig_out_fc_1(Is, Arity, Regs, [I|Acc])
end;
dig_out_fc_1([_|_], _Arity, _Regs, _Acc) ->
{#{},[]};
dig_out_fc_1([], _Arity, Regs, Acc) ->
{Regs,Acc}.
dig_out_fc_block([{set,[],[],{alloc,Live,_}}|Is], Regs0) ->
Regs = prune_xregs(Live, Regs0),
dig_out_fc_block(Is, Regs);
dig_out_fc_block([{set,[Dst],[Hd,Tl],put_list}|Is], Regs0) ->
Regs = Regs0#{Dst=>{cons,get_reg(Hd, Regs0),get_reg(Tl, Regs0)}},
dig_out_fc_block(Is, Regs);
dig_out_fc_block([{set,[Dst],[Src],move}|Is], Regs0) ->
Regs = Regs0#{Dst=>get_reg(Src, Regs0)},
dig_out_fc_block(Is, Regs);
dig_out_fc_block([{set,_,_,_}|_], _Regs) ->
%% Unknown instruction. Fail.
#{};
dig_out_fc_block([], Regs) -> Regs.
dig_out_stack_live(Regs, Default) ->
Reg = {x,2},
case Regs of
#{Reg:=List} ->
dig_out_stack_live_1(List, Default);
#{} ->
Default
end.
dig_out_stack_live_1({cons,{arg,N},T}, Live) ->
dig_out_stack_live_1(T, max(N + 1, Live));
dig_out_stack_live_1({cons,_,T}, Live) ->
dig_out_stack_live_1(T, Live);
dig_out_stack_live_1(nil, Live) ->
Live;
dig_out_stack_live_1(_, Live) -> Live.
prune_xregs(Live, Regs) ->
maps:filter(fun({x,X}, _) -> X < Live end, Regs).
moves_from_stack({cons,{arg,N},_}, I, _Acc) when N =/= I ->
%% Wrong argument. Give up.
{[],-1};
moves_from_stack({cons,H,T}, I, Acc) ->
case H of
{arg,I} ->
moves_from_stack(T, I+1, Acc);
_ ->
moves_from_stack(T, I+1, [{move,H,{x,I}}|Acc])
end;
moves_from_stack(nil, I, Acc) ->
{reverse(Acc),I};
moves_from_stack({literal,[H|T]}, I, Acc) ->
Cons = {cons,tag_literal(H),tag_literal(T)},
moves_from_stack(Cons, I, Acc);
moves_from_stack(_, _, _) ->
%% Not understood. Give up.
{[],-1}.
get_reg(R, Regs) ->
case Regs of
#{R:=Val} -> Val;
#{} -> R
end.
tag_literal([]) -> nil;
tag_literal(T) when is_atom(T) -> {atom,T};
tag_literal(T) when is_float(T) -> {float,T};
tag_literal(T) when is_integer(T) -> {integer,T};
tag_literal(T) -> {literal,T}.
