From 528f17ad9b85c4a3a1e28428606494550eef3a1e Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= Date: Mon, 27 May 2019 15:34:35 +0200 Subject: Eliminate crash in the beam_ssa_dead compiler pass The compiler could crash in the beam_ssa_dead pass while compiling complex nested `case` expressions. See the added test case for an example and explanation. https://bugs.erlang.org/browse/ERL-956 --- lib/compiler/src/beam_ssa_dead.erl | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) (limited to 'lib/compiler/src/beam_ssa_dead.erl') diff --git a/lib/compiler/src/beam_ssa_dead.erl b/lib/compiler/src/beam_ssa_dead.erl index bb43a550ae..86f680c964 100644 --- a/lib/compiler/src/beam_ssa_dead.erl +++ b/lib/compiler/src/beam_ssa_dead.erl @@ -436,8 +436,22 @@ get_phi_arg([{Val,From}|_], From) -> Val; get_phi_arg([_|As], From) -> get_phi_arg(As, From). eval_terminator(#b_br{bool=#b_var{}=Bool}=Br, Bs, _St) -> - Val = get_value(Bool, Bs), - beam_ssa:normalize(Br#b_br{bool=Val}); + case get_value(Bool, Bs) of + #b_literal{val=Val}=Lit -> + case is_boolean(Val) of + true -> + beam_ssa:normalize(Br#b_br{bool=Lit}); + false -> + %% Non-boolean literal. This means that this `br` + %% terminator will never actually be reached with + %% these bindings. (There must be a previous two-way + %% branch that branches the other way when Bool + %% is bound to a non-boolean literal.) + none + end; + #b_var{}=Var -> + beam_ssa:normalize(Br#b_br{bool=Var}) + end; eval_terminator(#b_br{bool=#b_literal{}}=Br, _Bs, _St) -> beam_ssa:normalize(Br); eval_terminator(#b_switch{arg=Arg,fail=Fail,list=List}=Sw, Bs, St) -> -- cgit v1.2.3