diff options
| -rw-r--r-- | lib/compiler/src/sys_core_fold.erl | 78 |
1 files changed, 77 insertions, 1 deletions
diff --git a/lib/compiler/src/sys_core_fold.erl b/lib/compiler/src/sys_core_fold.erl index d1eec9e347..c45c7aa1de 100644 --- a/lib/compiler/src/sys_core_fold.erl +++ b/lib/compiler/src/sys_core_fold.erl @@ -349,7 +349,12 @@ expr(#c_case{}=Case0, Ctxt, Sub) -> Case = Case1#c_case{arg=Arg2,clauses=Cs2}, warn_no_clause_match(Case1, Case), Expr = eval_case(Case, Sub), - bsm_an(Expr); + case move_case_into_arg(Case, Sub) of + impossible -> + bsm_an(Expr); + Other -> + expr(Other, Ctxt, sub_new_preserve_types(Sub)) + end; Other -> expr(Other, Ctxt, Sub) end; @@ -2571,6 +2576,77 @@ opt_simple_let_2(Let, Vs0, Arg0, Body, value, Sub) -> value, Sub) end. +move_case_into_arg(#c_case{arg=#c_let{vars=OuterVars0,arg=OuterArg, + body=InnerArg0}=Outer, + clauses=InnerClauses}=Inner, Sub) -> + %% + %% case let <OuterVars> = <OuterArg> in <InnerArg> of + %% <InnerClauses> + %% end + %% + %% ==> + %% + %% let <OuterVars> = <OuterArg> + %% in case <InnerArg> of <InnerClauses> end + %% + ScopeSub0 = sub_subst_scope(Sub#sub{t=[]}), + {OuterVars,ScopeSub} = pattern_list(OuterVars0, ScopeSub0), + InnerArg = body(InnerArg0, ScopeSub), + Outer#c_let{vars=OuterVars,arg=OuterArg, + body=Inner#c_case{arg=InnerArg,clauses=InnerClauses}}; +move_case_into_arg(#c_case{arg=#c_case{arg=OuterArg, + clauses=[OuterCa0,OuterCb]}=Outer, + clauses=InnerClauses}=Inner0, Sub) -> + case is_failing_clause(OuterCb) of + true -> + #c_clause{pats=OuterPats0,guard=OuterGuard0, + body=InnerArg0} = OuterCa0, + %% + %% case case <OuterArg> of + %% <OuterPats> when <OuterGuard> -> <InnerArg> + %% <OuterCb> + %% ... + %% end of + %% <InnerClauses> + %% end + %% + %% ==> + %% + %% case <OuterArg> of + %% <OuterPats> when <OuterGuard> -> + %% case <InnerArg> of <InnerClauses> end + %% <OuterCb> + %% end + %% + ScopeSub0 = sub_subst_scope(Sub#sub{t=[]}), + {OuterPats,ScopeSub} = pattern_list(OuterPats0, ScopeSub0), + OuterGuard = guard(OuterGuard0, ScopeSub), + InnerArg = body(InnerArg0, ScopeSub), + Inner = Inner0#c_case{arg=InnerArg,clauses=InnerClauses}, + OuterCa = OuterCa0#c_clause{pats=OuterPats,guard=OuterGuard, + body=Inner}, + Outer#c_case{arg=OuterArg, + clauses=[OuterCa,OuterCb]}; + false -> + impossible + end; +move_case_into_arg(#c_case{arg=#c_seq{arg=OuterArg,body=InnerArg}=Outer, + clauses=InnerClauses}=Inner, _Sub) -> + %% + %% case do <OuterArg> <InnerArg> of + %% <InnerClauses> + %% end + %% + %% ==> + %% + %% do <OuterArg> + %% case <InnerArg> of <InerClauses> end + %% + Outer#c_seq{arg=OuterArg, + body=Inner#c_case{arg=InnerArg,clauses=InnerClauses}}; +move_case_into_arg(_, _) -> + impossible. + %% In guards only, rewrite a case in a let argument like %% %% let <Var> = case <> of |