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authorBjörn Gustavsson <[email protected]>2011-12-21 06:44:28 +0100
committerBjörn Gustavsson <[email protected]>2012-01-04 10:49:15 +0100
commit53bd4974a1012669fb7db09815fabac01b586c12 (patch)
treec2c1bc82febe57acf81969bee72b57af4181f308 /lib/compiler/src
parent8769a849dbbb70cb92733f484b2a0e1693e97eb7 (diff)
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Eliminate the match_fail primop in v3_kernel and later passes
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
Diffstat (limited to 'lib/compiler/src')
-rw-r--r--lib/compiler/src/v3_codegen.erl37
-rw-r--r--lib/compiler/src/v3_kernel.erl22
-rw-r--r--lib/compiler/src/v3_life.erl34
3 files changed, 15 insertions, 78 deletions
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;