[erlc] internal consistency check failed: "illegal_branch, try_handler"

[RobinMorisset]

On master,

f(X, #{0 := X, 0 := Y}) ->
    try #{ok => ok} of
        Y ->
            bnot (Y = X)
    after
        ok
    end.

crashes erlc with the message:

consistency_try:1: function f/2+13:
  Internal consistency check failed - please report this bug.
  Instruction: {jump,{f,8}}
  Error:       {illegal_branch,try_handler,8}:

[RobinMorisset]

A couple of other testcases with the same error message:

f(X, Y) ->
    try Y of
        X ->
            (?MODULE:f1(
                try ([_ | _] = Y) of
                    X ->
                        ok
                after
                    ok
                end
            ) orelse X) bsl 0
    after
        ok
    end.

f1(_) ->
    ok.

and

f(X) ->
    {
        X ++ (X = get()),
        <<
            (ok):(catch (0 +
                try
                    [ok || _ <- []]
                catch
                    _ ->
                        X
                end))
        >>
    }.

[jhogberg]

Another variant:

f(X) when true; X ->
    - maybe
        <<>> ?= X,
        f(maybe
            0 ?= ([] =< ok)
        end),
        <<>> ?= ok
    else
        false  ->
            X;
        0  ->
            X
    end.

[jhogberg]

Another variant:

f(X) ->
    Y =
        try
            false = X
        catch
            _ ->
                ok
        end /= ok,
    X = Y,
    false = Y,
    0 = ok.

[bjorng]

Another variant:

f(X, #{0 := X, 0 := Y}, Y = [_ | _]) ->
    try
        Y = ok
    catch
        _ ->
            [_ | []] = Y = X
    end.

[RobinMorisset]

Another infinite loop in the compiler (same as #6599 (comment) above), this time without using maybe:

f(_, []) ->
    0;
f(X, _) ->
    ?MODULE:foo(
        <<>> =
            try f(ok, X) + 0 of
                X ->
                    X
            catch
                _ ->
                    X
            end
    );
f(_, _) ->
    ok.

I believe that it is a duplicate of this bug because it is fixed by #6619

[jhogberg]

Another variant:

f(X, _, X, X) ->
    ok;
f(X, (X = -0.0), (X = Y), _) ->
    -Y.

[RobinMorisset]

Another probable variant:

f(X, X) when is_integer(X) ->
    ok;
f(Y, Y = #{}) ->
    Y#{ok := ok}.

results in

test7150:1: function f/2+12:
  Internal consistency check failed - please report this bug.
  Instruction: {put_map_exact,{f,0},
                              {x,0},
                              {x,0},
                              1,
                              {list,[{atom,ok},{atom,ok}]}}
  Error:       {bad_type,{needed,{t_map,any,any}},{actual,any}}:

[jhogberg]

Another probable variant:

Thanks, I can confirm it's the same issue. :-)

[RobinMorisset]

Another likely variant, but this time with bad_typed_register (new I think):

f(_V0) ->
    case
        trunc(
            try
                trunc(<<>> = _V0)
            catch
                _ ->
                    0.0
            end
        )
    of
        _V0 -> ok;
        _ -> 42
    end.

resulting in

test70284:1: function f/1+14:
  Internal consistency check failed - please report this bug.
  Instruction: {test,is_eq_exact,
                     {f,4},
                     [{tr,{y,0},{t_integer,any}},{integer,0}]}
  Error:       {bad_typed_register,{t_bitstring,256,true},{t_integer,any}}:

[RobinMorisset]

Yet another likely variant, with yet another symptom:

f(_V0, _V1 = _V0) when _V1; _V0 ->
    _V0#{ok := ok},
    try _V0 of
        _V1 ->
            _V1
    after
        ok
    end#{
        ok := ok
    }.

results in

Function: f/2
/home/rmorisset/minimized/test168208.erl: internal error in pass beam_ssa_codegen:
exception error: no function clause matching beam_ssa_codegen:cg_instr(put_map,[{atom,exact},{atom,true},{atom,ok},{atom,ok}],{x,0}) 
  in function  beam_ssa_codegen:cg_block/3 (beam_ssa_codegen.erl, line 1381)
  in call from beam_ssa_codegen:cg_linear/2 (beam_ssa_codegen.erl, line 986)
  in call from beam_ssa_codegen:cg_linear/2 (beam_ssa_codegen.erl, line 987)
  in call from beam_ssa_codegen:cg_fun/3 (beam_ssa_codegen.erl, line 177)
  in call from beam_ssa_codegen:function/4 (beam_ssa_codegen.erl, line 129)
  in call from lists:mapfoldl_1/3 (lists.erl, line 1706)
  in call from beam_ssa_codegen:module/2 (beam_ssa_codegen.erl, line 51)

[bjorng]

Yet another likely variant, with yet another symptom

I don't think so. It crashes in another compiler pass. Please put this one into a new issue.

[bjorng]

Here is another one from #7285:

f(_V0, _V1 = _V0) ->
  _V0#{},
  (case _V0 of _V1 -> _V1 end)#{ok => ok}.