diff options
| -rw-r--r-- | lib/compiler/src/v3_core.erl | 44 |
1 files changed, 24 insertions, 20 deletions
diff --git a/lib/compiler/src/v3_core.erl b/lib/compiler/src/v3_core.erl index 8074456be2..72649e5c9f 100644 --- a/lib/compiler/src/v3_core.erl +++ b/lib/compiler/src/v3_core.erl @@ -1853,27 +1853,22 @@ uguard(Pg, Gs0, Ks, St0) -> %% uexprs([Kexpr], [KnownVar], State) -> {[Kexpr],State}. uexprs([#imatch{anno=A,pat=P0,arg=Arg,fc=Fc}|Les], Ks, St0) -> - %% Optimise for simple set of unbound variable. - case upattern(P0, Ks, St0) of - {#c_var{},[],_Pvs,_Pus,_} -> - %% Throw our work away and just set to iset. + case upat_is_new_var(P0, Ks) of + true -> + %% Assignment to a new variable. uexprs([#iset{var=P0,arg=Arg}|Les], Ks, St0); - _Other -> - %% Throw our work away and set to icase. - if - Les =:= [] -> - %% Need to explicitly return match "value", make - %% safe for efficiency. - {La0,Lps,St1} = force_safe(Arg, St0), - La = mark_compiler_generated(La0), - Mc = #iclause{anno=A,pats=[P0],guard=[],body=[La]}, - uexprs(Lps ++ [#icase{anno=A, - args=[La0],clauses=[Mc],fc=Fc}], Ks, St1); - true -> - Mc = #iclause{anno=A,pats=[P0],guard=[],body=Les}, - uexprs([#icase{anno=A,args=[Arg], - clauses=[Mc],fc=Fc}], Ks, St0) - end + false when Les =:= [] -> + %% Need to explicitly return match "value", make + %% safe for efficiency. + {La0,Lps,St1} = force_safe(Arg, St0), + La = mark_compiler_generated(La0), + Mc = #iclause{anno=A,pats=[P0],guard=[],body=[La]}, + uexprs(Lps ++ [#icase{anno=A, + args=[La0],clauses=[Mc],fc=Fc}], Ks, St1); + false -> + Mc = #iclause{anno=A,pats=[P0],guard=[],body=Les}, + uexprs([#icase{anno=A,args=[Arg], + clauses=[Mc],fc=Fc}], Ks, St0) end; uexprs([Le0|Les0], Ks, St0) -> {Le1,St1} = uexpr(Le0, Ks, St0), @@ -1881,6 +1876,15 @@ uexprs([Le0|Les0], Ks, St0) -> {[Le1|Les1],St2}; uexprs([], _, St) -> {[],St}. +%% upat_is_new_var(Pattern, [KnownVar]) -> true|false. +%% Test whether the pattern is a single, previously unknown +%% variable. + +upat_is_new_var(#c_var{name=V}, Ks) -> + not is_element(V, Ks); +upat_is_new_var(_, _) -> + false. + %% Mark a "safe" as compiler-generated. mark_compiler_generated(#c_cons{anno=A,hd=H,tl=T}) -> ann_c_cons([compiler_generated|A], mark_compiler_generated(H), |