From 331de9413f4f82db41dfbe60f521b21880b6688e Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= Date: Sun, 14 Apr 2019 07:45:54 +0200 Subject: Eliminate the beam_except pass The beam_except pass rewrites certain calls `erlang:error/{1,2}` to use specialized instructions for common exceptions such as `{badmatch,Term}`. Move this optimization to `beam_ssa_pre_codegen` and `beam_ssa_codegen`. The main reason for this change is that optimization passes operating on SSA code are easier to maintain than optimization passes working on BEAM code. --- lib/compiler/src/beam_ssa_codegen.erl | 74 ++++++++++++++++++++++++++++++++--- 1 file changed, 69 insertions(+), 5 deletions(-) (limited to 'lib/compiler/src/beam_ssa_codegen.erl') diff --git a/lib/compiler/src/beam_ssa_codegen.erl b/lib/compiler/src/beam_ssa_codegen.erl index c2d5035b19..5ce44c97db 100644 --- a/lib/compiler/src/beam_ssa_codegen.erl +++ b/lib/compiler/src/beam_ssa_codegen.erl @@ -37,7 +37,8 @@ used_labels=gb_sets:empty() :: gb_sets:set(ssa_label()), regs=#{} :: #{beam_ssa:var_name()=>ssa_register()}, ultimate_fail=1 :: beam_label(), - catches=gb_sets:empty() :: gb_sets:set(ssa_label()) + catches=gb_sets:empty() :: gb_sets:set(ssa_label()), + fc_label=1 :: beam_label() }). -spec module(beam_ssa:b_module(), [compile:option()]) -> @@ -124,7 +125,7 @@ function(#b_function{anno=Anno,bs=Blocks}, AtomMod, St0) -> Labels = (St4#cg.labels)#{0=>Entry,?BADARG_BLOCK=>0}, St5 = St4#cg{labels=Labels,used_labels=gb_sets:singleton(Entry), ultimate_fail=Ult}, - {Body,St} = cg_fun(Blocks, St5), + {Body,St} = cg_fun(Blocks, St5#cg{fc_label=Fi}), Asm = [{label,Fi},line(Anno), {func_info,AtomMod,{atom,Name},Arity}] ++ add_parameter_annos(Body, Anno) ++ @@ -384,6 +385,7 @@ classify_heap_need(is_tagged_tuple) -> neutral; classify_heap_need(kill_try_tag) -> gc; classify_heap_need(landingpad) -> gc; classify_heap_need(make_fun) -> gc; +classify_heap_need(match_fail) -> gc; classify_heap_need(new_try_tag) -> gc; classify_heap_need(peek_message) -> gc; classify_heap_need(put_map) -> gc; @@ -1160,6 +1162,10 @@ cg_block([#cg_set{op=call}=I, #cg_set{op=succeeded,dst=Bool}], {Bool,_Fail}, St) -> %% A call in try/catch block. cg_block([I], none, St); +cg_block([#cg_set{op=match_fail}=I, + #cg_set{op=succeeded,dst=Bool}], {Bool,_Fail}, St) -> + %% A match_fail instruction in a try/catch block. + cg_block([I], none, St); cg_block([#cg_set{op=Op,dst=Dst0,args=Args0}=I, #cg_set{op=succeeded,dst=Bool}], {Bool,Fail}, St) -> [Dst|Args] = beam_args([Dst0|Args0], St), @@ -1216,6 +1222,28 @@ cg_block([#cg_set{op=copy}|_]=T0, Context, St0) -> no -> {Is,St} end; +cg_block([#cg_set{op=match_fail,args=Args0,anno=Anno}], none, St) -> + Args = beam_args(Args0, St), + Is = cg_match_fail(Args, line(Anno), none), + {Is,St}; +cg_block([#cg_set{op=match_fail,args=Args0,anno=Anno}|T], Context, St0) -> + FcLabel = case Context of + {return,_,none} -> + %% There is no stack frame. If this is a function_clause + %% exception, it is safe to jump to the label of the + %% func_info instruction. + St0#cg.fc_label; + _ -> + %% This is most probably not a function_clause. + %% If this is a function_clause exception + %% (rare), it is not safe to jump to the + %% func_info label. + none + end, + Args = beam_args(Args0, St0), + Is0 = cg_match_fail(Args, line(Anno), FcLabel), + {Is1,St} = cg_block(T, Context, St0), + {Is0++Is1,St}; cg_block([#cg_set{op=Op,dst=Dst0,args=Args0}=Set], none, St) -> [Dst|Args] = beam_args([Dst0|Args0], St), Is = cg_instr(Op, Args, Dst, Set), @@ -1489,6 +1517,42 @@ cg_call(#cg_set{anno=Anno,op=call,dst=Dst0,args=Args0}, Is = setup_args(Args++[Func], Anno, Context, St) ++ Line ++ Call, {Is,St}. +cg_match_fail([{atom,function_clause}|Args], Line, Fc) -> + case Fc of + none -> + %% There is a stack frame (probably because of inlining). + %% Jumping to the func_info label is not allowed by + %% beam_validator. Rewrite the instruction as a call to + %% erlang:error/2. + make_fc(Args, Line); + _ -> + setup_args(Args) ++ [{jump,{f,Fc}}] + end; +cg_match_fail([{atom,Op}], Line, _Fc) -> + [Line,Op]; +cg_match_fail([{atom,Op},Val], Line, _Fc) -> + [Line,{Op,Val}]. + +make_fc(Args, Line) -> + %% Recreate the original call to erlang:error/2. + Live = foldl(fun({x,X}, A) -> max(X+1, A); + (_, A) -> A + end, 0, Args), + TmpReg = {x,Live}, + StkMoves = build_stk(reverse(Args), TmpReg, nil), + [{test_heap,2*length(Args),Live}|StkMoves] ++ + [{move,{atom,function_clause},{x,0}}, + Line, + {call_ext,2,{extfunc,erlang,error,2}}]. + +build_stk([V], _TmpReg, Tail) -> + [{put_list,V,Tail,{x,1}}]; +build_stk([V|Vs], TmpReg, Tail) -> + I = {put_list,V,Tail,TmpReg}, + [I|build_stk(Vs, TmpReg, TmpReg)]; +build_stk([], _TmpReg, nil) -> + [{move,nil,{x,1}}]. + build_call(call_fun, Arity, _Func, none, Dst) -> [{call_fun,Arity}|copy({x,0}, Dst)]; build_call(call_fun, Arity, _Func, {return,Dst,N}, Dst) when is_integer(N) -> @@ -1527,15 +1591,15 @@ build_apply(Arity, {return,Val,N}, _Dst) when is_integer(N) -> build_apply(Arity, none, Dst) -> [{apply,Arity}|copy({x,0}, Dst)]. -cg_instr(put_map, [{atom,assoc},SrcMap|Ss], Dst, Set) -> - Live = get_live(Set), - [{put_map_assoc,{f,0},SrcMap,Dst,Live,{list,Ss}}]; cg_instr(bs_get_tail, [Src], Dst, Set) -> Live = get_live(Set), [{bs_get_tail,Src,Dst,Live}]; cg_instr(bs_get_position, [Ctx], Dst, Set) -> Live = get_live(Set), [{bs_get_position,Ctx,Dst,Live}]; +cg_instr(put_map, [{atom,assoc},SrcMap|Ss], Dst, Set) -> + Live = get_live(Set), + [{put_map_assoc,{f,0},SrcMap,Dst,Live,{list,Ss}}]; cg_instr(Op, Args, Dst, _Set) -> cg_instr(Op, Args, Dst). -- cgit v1.2.3