From 53bd4974a1012669fb7db09815fabac01b586c12 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= Date: Wed, 21 Dec 2011 06:44:28 +0100 Subject: Eliminate the match_fail primop in v3_kernel and later passes MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit In the v3_life pass, it is assumed that a 'match_fail' primop only occur at the top-level and at the end of a function. But this code: do_split_cases(A) -> case A of x -> Z = dummy1; _ -> Z = dummy2, a=b end, Z. will be optimized by sys_core_fold to the following code: 'split_cases'/1 = fun (_cor0) -> let <_cor7,Z> = case _cor0 of <'x'> when 'true' -> < 'dummy1','dummy1' > <_cor6> when 'true' -> %% Here follows a 'match_fail' primop inside %% multiple return values: < primop 'match_fail'({'badmatch','b'}),'dummy2' > end in Z moving the 'match_fail' primop into a "values" construction. In the future, we would like to get rid of the v3_life pass (it is there for historical reasons), so in the mean-time we prefer to not add more code to it by generalizing the handling of 'match_fail'. Since the 'match_fail' primop can be simulated by erlang:error/{1,2}, the simplest solution is to translate 'match_fail' to a call to erlang:error/{1,2} in v3_kernel and remove the handling of 'match_fail' in v3_life and v3_codegen. It is tempting to get rid of 'match_fail' also in the Core Erlang format, but there are two issues: - Removing the support for 'match_fail' completely may break tools that generate Core Erlang code. We should not do that in a minor release. - There is no easy way to generate a 'function_clause' exception that will remain correct if it will be inlined into another function. (Calling "erlang:error(function_clause, Args)" is fine only if it is not inlined into another function.) A good solution probably involves introducing new instructions, which is better done in a major release. Noticed-by: Håkan Matsson Minimized-test-case-by: Erik Søe Sørensen --- lib/compiler/src/v3_codegen.erl | 37 ------------------------------------- lib/compiler/src/v3_kernel.erl | 22 +++++++++++++--------- lib/compiler/src/v3_life.erl | 34 ++-------------------------------- 3 files changed, 15 insertions(+), 78 deletions(-) (limited to 'lib/compiler/src') diff --git a/lib/compiler/src/v3_codegen.erl b/lib/compiler/src/v3_codegen.erl index e7dae67085..6623485609 100644 --- a/lib/compiler/src/v3_codegen.erl +++ b/lib/compiler/src/v3_codegen.erl @@ -53,7 +53,6 @@ %% Main codegen structure. -record(cg, {lcount=1, %Label counter - finfo, %Function info label bfail, %Fail label for BIFs break, %Break label recv, %Receive label @@ -126,7 +125,6 @@ cg_fun(Les, Hvs, Vdb, AtomMod, NameArity, Anno, St0) -> stk=[]}, 0, Vdb), {B,_Aft,St} = cg_list(Les, 0, Vdb, Bef, St3#cg{bfail=0, - finfo=Fi, ultimate_failure=UltimateMatchFail, is_top_block=true}), {Name,Arity} = NameArity, @@ -147,8 +145,6 @@ cg({match,M,Rs}, Le, Vdb, Bef, St) -> match_cg(M, Rs, Le, Vdb, Bef, St); cg({guard_match,M,Rs}, Le, Vdb, Bef, St) -> guard_match_cg(M, Rs, Le, Vdb, Bef, St); -cg({match_fail,F}, Le, Vdb, Bef, St) -> - match_fail_cg(F, Le, Vdb, Bef, St); cg({call,Func,As,Rs}, Le, Vdb, Bef, St) -> call_cg(Func, As, Rs, Le, Vdb, Bef, St); cg({enter,Func,As}, Le, Vdb, Bef, St) -> @@ -294,39 +290,6 @@ match_cg({block,Es}, Le, _Fail, Bef, St) -> Int = clear_dead(Bef, Le#l.i, Le#l.vdb), block_cg(Es, Le, Int, St). -%% match_fail_cg(FailReason, Le, Vdb, StackReg, State) -> -%% {[Ainstr],StackReg,State}. -%% Generate code for the match_fail "call". N.B. there is no generic -%% case for when the fail value has been created elsewhere. - -match_fail_cg({function_clause,As}, Le, Vdb, Bef, St) -> - %% Must have the args in {x,0}, {x,1},... - {Sis,Int} = cg_setup_call(As, Bef, Le#l.i, Vdb), - {Sis ++ [{jump,{f,St#cg.finfo}}], - Int#sr{reg=clear_regs(Int#sr.reg)},St}; -match_fail_cg({badmatch,Term}, Le, Vdb, Bef, St) -> - R = cg_reg_arg(Term, Bef), - Int0 = clear_dead(Bef, Le#l.i, Vdb), - {Sis,Int} = adjust_stack(Int0, Le#l.i, Le#l.i+1, Vdb), - {Sis ++ [line(Le),{badmatch,R}], - Int#sr{reg=clear_regs(Int0#sr.reg)},St}; -match_fail_cg({case_clause,Reason}, Le, Vdb, Bef, St) -> - R = cg_reg_arg(Reason, Bef), - Int0 = clear_dead(Bef, Le#l.i, Vdb), - {Sis,Int} = adjust_stack(Int0, Le#l.i, Le#l.i+1, Vdb), - {Sis++[line(Le),{case_end,R}], - Int#sr{reg=clear_regs(Bef#sr.reg)},St}; -match_fail_cg(if_clause, Le, Vdb, Bef, St) -> - Int0 = clear_dead(Bef, Le#l.i, Vdb), - {Sis,Int1} = adjust_stack(Int0, Le#l.i, Le#l.i+1, Vdb), - {Sis++[line(Le),if_end],Int1#sr{reg=clear_regs(Int1#sr.reg)},St}; -match_fail_cg({try_clause,Reason}, Le, Vdb, Bef, St) -> - R = cg_reg_arg(Reason, Bef), - Int0 = clear_dead(Bef, Le#l.i, Vdb), - {Sis,Int} = adjust_stack(Int0, Le#l.i, Le#l.i+1, Vdb), - {Sis ++ [line(Le),{try_case_end,R}], - Int#sr{reg=clear_regs(Int0#sr.reg)},St}. - %% bsm_rename_ctx([Clause], Var) -> [Clause] %% We know from an annotation that the register for a binary can %% be reused for the match context because the two are not truly diff --git a/lib/compiler/src/v3_kernel.erl b/lib/compiler/src/v3_kernel.erl index d76291f57f..f2eaa37617 100644 --- a/lib/compiler/src/v3_kernel.erl +++ b/lib/compiler/src/v3_kernel.erl @@ -83,6 +83,7 @@ -import(lists, [map/2,foldl/3,foldr/3,mapfoldl/3,splitwith/2,member/2, keymember/3,keyfind/3]). -import(ordsets, [add_element/2,del_element/2,union/2,union/1,subtract/2]). +-import(cerl, [c_tuple/1]). -include("core_parse.hrl"). -include("v3_kernel.hrl"). @@ -422,10 +423,11 @@ expr(#c_call{anno=A,module=M0,name=F0,args=Cargs}, Sub, St0) -> end; expr(#c_primop{anno=A,name=#c_literal{val=match_fail},args=Cargs0}, Sub, St0) -> Cargs = translate_match_fail(Cargs0, Sub, A, St0), - %% This special case will disappear. {Kargs,Ap,St} = atomic_list(Cargs, Sub, St0), Ar = length(Cargs), - Call = #k_call{anno=A,op=#k_internal{name=match_fail,arity=Ar},args=Kargs}, + Call = #k_call{anno=A,op=#k_remote{mod=#k_atom{val=erlang}, + name=#k_atom{val=error}, + arity=Ar},args=Kargs}, {Call,Ap,St}; expr(#c_primop{anno=A,name=#c_literal{val=N},args=Cargs}, Sub, St0) -> {Kargs,Ap,St1} = atomic_list(Cargs, Sub, St0), @@ -455,14 +457,14 @@ expr(#ireceive_accept{anno=A}, _Sub, St) -> {#k_receive_accept{anno=A},[],St}. translate_match_fail(Args, Sub, Anno, St) -> case Args of [#c_tuple{es=[#c_literal{val=function_clause}|As]}] -> - translate_match_fail_1(Anno, Args, As, Sub, St); + translate_match_fail_1(Anno, As, Sub, St); [#c_literal{val=Tuple}] when is_tuple(Tuple) -> %% The inliner may have created a literal out of %% the original #c_tuple{}. case tuple_to_list(Tuple) of [function_clause|As0] -> As = [#c_literal{val=E} || E <- As0], - translate_match_fail_1(Anno, Args, As, Sub, St); + translate_match_fail_1(Anno, As, Sub, St); _ -> Args end; @@ -471,7 +473,7 @@ translate_match_fail(Args, Sub, Anno, St) -> Args end. -translate_match_fail_1(Anno, Args, As, Sub, #kern{ff=FF}) -> +translate_match_fail_1(Anno, As, Sub, #kern{ff=FF}) -> AnnoFunc = case keyfind(function_name, 1, Anno) of false -> none; %Force rewrite. @@ -481,10 +483,10 @@ translate_match_fail_1(Anno, Args, As, Sub, #kern{ff=FF}) -> case {AnnoFunc,FF} of {Same,Same} -> %% Still in the correct function. - Args; + translate_fc(As); {{F,_},F} -> %% Still in the correct function. - Args; + translate_fc(As); _ -> %% Wrong function or no function_name annotation. %% @@ -493,9 +495,12 @@ translate_match_fail_1(Anno, Args, As, Sub, #kern{ff=FF}) -> %% the current function). match_fail(function_clause) will %% only work at the top level of the function it was originally %% defined in, so we will need to rewrite it to a case_clause. - [#c_tuple{es=[#c_literal{val=case_clause},#c_tuple{es=As}]}] + [c_tuple([#c_literal{val=case_clause},c_tuple(As)])] end. +translate_fc(Args) -> + [#c_literal{val=function_clause},make_list(Args)]. + %% call_type(Module, Function, Arity) -> call | bif | apply | error. %% Classify the call. call_type(#c_literal{val=M}, #c_literal{val=F}, Ar) when is_atom(M), is_atom(F) -> @@ -1494,7 +1499,6 @@ iletrec_funs_gen(Fs, FreeVs, St) -> %% is_exit_expr(Kexpr) -> boolean(). %% Test whether Kexpr always exits and never returns. -is_exit_expr(#k_call{op=#k_internal{name=match_fail,arity=1}}) -> true; is_exit_expr(#k_receive_next{}) -> true; is_exit_expr(_) -> false. diff --git a/lib/compiler/src/v3_life.erl b/lib/compiler/src/v3_life.erl index fac9a9843d..93f8034230 100644 --- a/lib/compiler/src/v3_life.erl +++ b/lib/compiler/src/v3_life.erl @@ -89,19 +89,8 @@ function(#k_fdef{anno=#k{a=Anno},func=F,arity=Ar,vars=Vs,body=Kb}) -> end. %% body(Kbody, I, Vdb) -> {[Expr],MaxI,Vdb}. -%% Handle a body, need special cases for transforming match_fails. -%% We KNOW that they only occur last in a body. - -body(#k_seq{arg=#k_put{anno=Pa,arg=Arg,ret=[R]}, - body=#k_enter{anno=Ea,op=#k_internal{name=match_fail,arity=1}, - args=[R]}}, - I, Vdb0) -> - Vdb1 = use_vars(Pa#k.us, I, Vdb0), %All used here - {[match_fail(Arg, I, Pa#k.a ++ Ea#k.a)],I,Vdb1}; -body(#k_enter{anno=Ea,op=#k_internal{name=match_fail,arity=1},args=[Arg]}, - I, Vdb0) -> - Vdb1 = use_vars(Ea#k.us, I, Vdb0), - {[match_fail(Arg, I, Ea#k.a)],I,Vdb1}; +%% Handle a body. + body(#k_seq{arg=Ke,body=Kb}, I, Vdb0) -> %%ok = io:fwrite("life ~w:~p~n", [?LINE,{Ke,I,Vdb0}]), A = get_kanno(Ke), @@ -353,25 +342,6 @@ guard_clause(#k_guard_clause{anno=A,guard=Kg,body=Kb}, Ls, I, Ctxt, Vdb0) -> i=I,vdb=use_vars((get_kanno(Kg))#k.us, I+2, Vdb1), a=A#k.a}. -%% match_fail(FailValue, I, Anno) -> Expr. -%% Generate the correct match_fail instruction. N.B. there is no -%% generic case for when the fail value has been created elsewhere. - -match_fail(#k_literal{anno=Anno,val={Atom,Val}}, I, A) when is_atom(Atom) -> - match_fail(#k_tuple{anno=Anno,es=[#k_atom{val=Atom},#k_literal{val=Val}]}, I, A); -match_fail(#k_literal{anno=Anno,val={Atom}}, I, A) when is_atom(Atom) -> - match_fail(#k_tuple{anno=Anno,es=[#k_atom{val=Atom}]}, I, A); -match_fail(#k_tuple{es=[#k_atom{val=function_clause}|As]}, I, A) -> - #l{ke={match_fail,{function_clause,literal_list(As, [])}},i=I,a=A}; -match_fail(#k_tuple{es=[#k_atom{val=badmatch},Val]}, I, A) -> - #l{ke={match_fail,{badmatch,literal(Val, [])}},i=I,a=A}; -match_fail(#k_tuple{es=[#k_atom{val=case_clause},Val]}, I, A) -> - #l{ke={match_fail,{case_clause,literal(Val, [])}},i=I,a=A}; -match_fail(#k_atom{val=if_clause}, I, A) -> - #l{ke={match_fail,if_clause},i=I,a=A}; -match_fail(#k_tuple{es=[#k_atom{val=try_clause},Val]}, I, A) -> - #l{ke={match_fail,{try_clause,literal(Val, [])}},i=I,a=A}. - %% type(Ktype) -> Type. type(k_literal) -> literal; -- cgit v1.2.3