From 726f6e4c7afe8ce37b30eedbebe583e7b9bfc51b Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= Date: Wed, 21 Dec 2011 07:41:48 +0100 Subject: Add the beam_except pass to optimize exceptions In order to save space, rewrite suitable calls to erlang:error/{1,2} to special BEAM instructions. This code is probably longer than the code taken out of v3_life and v3_codegen in the previous commit, but it is much easier to understand and maintain since the BEAM assembler format is better understood than the v3_life format. --- lib/compiler/src/beam_except.erl | 149 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 149 insertions(+) create mode 100644 lib/compiler/src/beam_except.erl (limited to 'lib/compiler/src/beam_except.erl') diff --git a/lib/compiler/src/beam_except.erl b/lib/compiler/src/beam_except.erl new file mode 100644 index 0000000000..fb1a43cd9e --- /dev/null +++ b/lib/compiler/src/beam_except.erl @@ -0,0 +1,149 @@ +%% +%% %CopyrightBegin% +%% +%% Copyright Ericsson AB 2011. All Rights Reserved. +%% +%% The contents of this file are subject to the Erlang Public License, +%% Version 1.1, (the "License"); you may not use this file except in +%% compliance with the License. You should have received a copy of the +%% Erlang Public License along with this software. If not, it can be +%% retrieved online at http://www.erlang.org/. +%% +%% Software distributed under the License is distributed on an "AS IS" +%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See +%% the License for the specific language governing rights 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]). + +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 = erlang:get_stacktrace(), + io:fwrite("Function: ~w/~w\n", [Name,Arity]), + erlang:raise(Class, Error, Stack) + end. + +-record(st, + {lbl, %func_info label + loc %location for func_info + }). + +function_1(Is0) -> + case Is0 of + [{label,Lbl},{line,Loc}|_] -> + St = #st{lbl=Lbl,loc=Loc}, + 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([{call_ext_only,Ar,{extfunc,erlang,error,Ar}}=I|Is], St, Acc) -> + translate_1(Ar, I, Is, St, Acc); +translate([{call_ext_last,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, [{line,_}=Line|Acc1]=Acc0) -> + case dig_out(Ar, Acc1) of + no -> + translate(Is, St, [I|Acc0]); + {yes,function_clause,Acc2} -> + case {Line,St} of + {{line,Loc},#st{lbl=Fi,loc=Loc}} -> + Instr = {jump,{f,Fi}}, + translate(Is, St, [Instr|Acc2]); + {_,_} -> + %% This must be "error(function_clause, Args)" in + %% the Erlang source code. Don't translate. + translate(Is, St, [I|Acc0]) + end; + {yes,Instr,Acc2} -> + translate(Is, St, [Instr,Line|Acc2]) + end. + +dig_out(Ar, [{kill,_}|Is]) -> + dig_out(Ar, Is); +dig_out(1, [{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(2, [{block,Bl}|Is]) -> + case dig_out_block_fc(Bl) of + no -> no; + {yes,What} -> {yes,What,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}],[Tuple],move}, + {set,[],[Value],put}, + {set,[],[{atom,Exc}],put}, + {set,[Tuple],[],{put_tuple,2}}|Is]) -> + translate_exception(Exc, Value, Is, 3); +dig_out_block([{set,[],[Value],put}, + {set,[],[{atom,Exc}],put}, + {set,[{x,0}],[],{put_tuple,2}}|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(Is0, Words) -> + [{set,[],[],{alloc,Live,{F1,F2,Needed,F3}}}|Is] = reverse(Is0), + [{set,[],[],{alloc,Live,{F1,F2,Needed-Words,F3}}}|Is]. + +dig_out_block_fc([{set,[],[],{alloc,Live,_}}|Bl]) -> + dig_out_fc(Bl, Live-1, nil); +dig_out_block_fc(_) -> no. + +dig_out_fc([{set,[Dst],[{x,Reg},Dst0],put_list}|Is], Reg, Dst0) -> + dig_out_fc(Is, Reg-1, Dst); +dig_out_fc([{set,[{x,0}],[{atom,function_clause}],move}], -1, {x,1}) -> + {yes,function_clause}; +dig_out_fc(_, _, _) -> no. -- cgit v1.2.3