File 0138-Eliminate-crash-when-optimization-passes-are-disable.patch of Package erlang
From c723601d49df30e6ffa7a2d8a40cdef973b67759 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= <bjorn@erlang.org>
Date: Tue, 14 Jun 2022 05:30:23 +0200
Subject: [PATCH] Eliminate crash when optimization passes are disabled
When compiling the following code with optimization passes disabled:
foo() ->
([<<bad/utf8>>] =
try
[whatever]
catch
_:_ when false ->
ok
end) ! (some_atom ++ <<>>).
`beam_validator` rejects the code with the following message:
some_module:1: function foo/0+11:
Internal consistency check failed - please report this bug.
Instruction: {get_hd,{literal,[whatever]},{x,0}}
Error: {literal_not_allowed,{literal,[whatever]}}:
All optimization passes are supposed to be optional, so this crash is
not acceptable even though the code is nonsensical. Eliminate the
crash by having `beam_ssa_pre_codegen` re-run its code cleaning
pass until there are no more unreachable blocks.
---
lib/compiler/src/beam_ssa_pre_codegen.erl | 78 ++++++++++++-----------
lib/compiler/test/beam_ssa_SUITE.erl | 14 ++++
2 files changed, 55 insertions(+), 37 deletions(-)
diff --git a/lib/compiler/src/beam_ssa_pre_codegen.erl b/lib/compiler/src/beam_ssa_pre_codegen.erl
index 0c7ee89bf0..c5b428759c 100644
--- a/lib/compiler/src/beam_ssa_pre_codegen.erl
+++ b/lib/compiler/src/beam_ssa_pre_codegen.erl
@@ -74,7 +74,7 @@
-import(lists, [all/2,any/2,append/1,duplicate/2,
foldl/3,last/1,member/2,partition/2,
reverse/1,reverse/2,seq/2,sort/1,
- splitwith/2,usort/1,zip/2]).
+ usort/1,zip/2]).
-spec module(beam_ssa:b_module(), [compile:option()]) ->
{'ok',beam_ssa:b_module()}.
@@ -588,10 +588,13 @@ bs_subst_ctx(Other, _CtxChain) ->
%% arguments. Evaluate the instructions and remove them.
sanitize(#st{ssa=Blocks0,cnt=Count0}=St) ->
- Ls = beam_ssa:rpo(Blocks0),
- {Blocks,Count} = sanitize(Ls, Blocks0, Count0, #{}),
+ {Blocks,Count} = sanitize(Blocks0, Count0),
St#st{ssa=Blocks,cnt=Count}.
+sanitize(Blocks, Counts) ->
+ Ls = beam_ssa:rpo(Blocks),
+ sanitize(Ls, Blocks, Counts, #{}).
+
sanitize([L|Ls], Blocks0, Count0, Values0) ->
#b_blk{is=Is0,last=Last0} = Blk0 = map_get(L, Blocks0),
case sanitize_is(Is0, Last0, Blocks0, Count0, Values0, false, []) of
@@ -603,21 +606,28 @@ sanitize([L|Ls], Blocks0, Count0, Values0) ->
sanitize(Ls, Blocks, Count, Values)
end;
sanitize([], Blocks0, Count, Values) ->
- Blocks = if
- map_size(Values) =:= 0 ->
- Blocks0;
- true ->
- RPO = beam_ssa:rpo(Blocks0),
- beam_ssa:rename_vars(Values, RPO, Blocks0)
- end,
+ Blocks1 = if
+ map_size(Values) =:= 0 ->
+ Blocks0;
+ true ->
+ RPO = beam_ssa:rpo(Blocks0),
+ beam_ssa:rename_vars(Values, RPO, Blocks0)
+ end,
%% Unreachable blocks can cause problems for the dominator calculations.
- Ls = beam_ssa:rpo(Blocks),
- Reachable = gb_sets:from_list(Ls),
- {case map_size(Blocks) =:= gb_sets:size(Reachable) of
- true -> Blocks;
- false -> remove_unreachable(Ls, Blocks, Reachable, [])
- end, Count}.
+ Linear = beam_ssa:linearize(Blocks1),
+ if
+ map_size(Blocks1) =:= length(Linear) ->
+ {Blocks1,Count};
+ true ->
+ %% Since blocks were removed, some phi nodes could have
+ %% been reduced to a single value. Single-valued phi nodes
+ %% can cause problem when beam_ssa_codegen does its own
+ %% constant propagation, so we will have re-run this pass
+ %% to get rid of any single-valued phi nodes.
+ Blocks = maps:from_list(Linear),
+ sanitize(Blocks, Count)
+ end.
sanitize_is([#b_set{op=get_map_element,args=Args0}=I0|Is],
Last, Blocks, Count0, Values, Changed, Acc) ->
@@ -702,6 +712,19 @@ sanitize_is([#b_set{op=bs_test_tail}=I], Last, Blocks, Count, Values,
_ ->
do_sanitize_is(I, [], Last, Blocks, Count, Values, Changed, Acc)
end;
+sanitize_is([#b_set{op=bs_get,args=Args0}=I0|Is], Last, Blocks, Count, Values,
+ Changed, Acc) ->
+ case {Args0,sanitize_args(Args0, Values)} of
+ {[_,_,_,#b_var{},_],[Type,Val,Flags,#b_literal{val=all},Unit]} ->
+ %% The size `all` is used for the size of the final binary
+ %% segment in a pattern. Using `all` explicitly is not allowed,
+ %% so we convert it to an obvious invalid size.
+ Args = [Type,Val,Flags,#b_literal{val=bad_size},Unit],
+ I = I0#b_set{args=Args},
+ sanitize_is(Is, Last, Blocks, Count, Values, true, [I|Acc]);
+ {_,_} ->
+ sanitize_is(Is, Last, Blocks, Count, Values, Changed, [I0|Acc])
+ end;
sanitize_is([#b_set{}=I|Is], Last, Blocks, Count, Values, Changed, Acc) ->
do_sanitize_is(I, Is, Last, Blocks, Count, Values, Changed, Acc);
sanitize_is([], Last, _Blocks, Count, Values, Changed, Acc) ->
@@ -807,27 +830,11 @@ sanitize_instr(is_tagged_tuple, [#b_literal{val=Tuple},
true ->
{value,false}
end;
+sanitize_instr(succeeded, [#b_literal{}], _I) ->
+ {value,true};
sanitize_instr(_, _, _) ->
ok.
-remove_unreachable([L|Ls], Blocks, Reachable, Acc) ->
- #b_blk{is=Is0} = Blk0 = map_get(L, Blocks),
- case split_phis(Is0) of
- {[_|_]=Phis,Rest} ->
- Is = [prune_phi(Phi, Reachable) || Phi <- Phis] ++ Rest,
- Blk = Blk0#b_blk{is=Is},
- remove_unreachable(Ls, Blocks, Reachable, [{L,Blk}|Acc]);
- {[],_} ->
- remove_unreachable(Ls, Blocks, Reachable, [{L,Blk0}|Acc])
- end;
-remove_unreachable([], _Blocks, _, Acc) ->
- maps:from_list(Acc).
-
-prune_phi(#b_set{args=Args0}=Phi, Reachable) ->
- Args = [A || {_,Pred}=A <- Args0,
- gb_sets:is_element(Pred, Reachable)],
- Phi#b_set{args=Args}.
-
phi_all_same_literal([{#b_literal{}=Arg, _From} | Phis]) ->
phi_all_same_literal_1(Phis, Arg);
phi_all_same_literal([_|_]) ->
@@ -3048,9 +3055,6 @@ rel2fam(S0) ->
S = sofs:rel2fam(S1),
sofs:to_external(S).
-split_phis(Is) ->
- splitwith(fun(#b_set{op=Op}) -> Op =:= phi end, Is).
-
is_yreg({y,_}) -> true;
is_yreg({x,_}) -> false;
is_yreg({z,_}) -> false;
diff --git a/lib/compiler/test/beam_ssa_SUITE.erl b/lib/compiler/test/beam_ssa_SUITE.erl
index d1330b78bf..21715fd15c 100644
--- a/lib/compiler/test/beam_ssa_SUITE.erl
+++ b/lib/compiler/test/beam_ssa_SUITE.erl
@@ -886,6 +886,8 @@ grab_bag(_Config) ->
{'EXIT',{{try_clause,[]},[_|_]}} = catch grab_bag_18(),
+ {'EXIT',{{badmatch,[whatever]},[_|_]}} = catch grab_bag_19(),
+
ok.
grab_bag_1() ->
@@ -1112,6 +1114,18 @@ grab_bag_18() ->
end
end.
+grab_bag_19() ->
+ ([<<bad/utf8>>] =
+ %% beam_ssa_pre_codegen would produce single-valued phi
+ %% nodes, which in turn would cause the constant propagation
+ %% in beam_ssa_codegen:prefer_xregs/2 to produce get_hd and
+ %% get_tl instructions with literal operands.
+ try
+ [whatever]
+ catch
+ _:_ when false ->
+ ok
+ end) ! (some_atom ++ <<>>).
redundant_br(_Config) ->
{false,{x,y,z}} = redundant_br_1(id({x,y,z})),
--
2.35.3
