File 0200-beam_ssa_throw-Remove-pointless-assertion-... of Package erlang

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File 0200-beam_ssa_throw-Remove-pointless-assertion-that-cause.patch of Package erlang (Revision 937f847f2956692f80dfc36d9f9dc085)

Currently displaying revision 937f847f2956692f80dfc36d9f9dc085 , Show latest

From 3a285636bcceff0cdd06e56a293bac952a4bc618 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?John=20H=C3=B6gberg?= <john@erlang.org>
Date: Thu, 10 Jun 2021 13:05:04 +0200
Subject: [PATCH] beam_ssa_throw: Remove pointless assertion that caused
 crashes

We don't have to care about this when simulating a throw, since we
will assume all paths are possible if we get the types wrong. We
only need to be careful not to assert something we cannot prove.
---
 lib/compiler/src/beam_ssa_throw.erl  | 10 +++++-----
 lib/compiler/test/trycatch_SUITE.erl | 26 ++++++++++++++++++++++++++
 2 files changed, 31 insertions(+), 5 deletions(-)

diff --git a/lib/compiler/src/beam_ssa_throw.erl b/lib/compiler/src/beam_ssa_throw.erl
index cf742ec6ce..ae70872730 100644
--- a/lib/compiler/src/beam_ssa_throw.erl
+++ b/lib/compiler/src/beam_ssa_throw.erl
@@ -418,12 +418,12 @@ ois_is([#b_set{op=get_tl,dst=Dst,args=[Src]} | Is], Ts0) ->
     {Type, _, _} = beam_call_types:types(erlang, tl, [SrcType]),
     Ts = Ts0#{ Dst => Type },
     ois_is(Is, Ts);
-ois_is([#b_set{op=get_tuple_element,dst=Dst,args=[Src, Offset]} | Is], Ts0) ->
+ois_is([#b_set{op=get_tuple_element,
+               dst=Dst,
+               args=[Src, #b_literal{val=Offset}]} | Is], Ts0) ->
     Type = case Ts0 of
-               #{ Src := #t_tuple{size=Size,elements=Es} } ->
-                   #b_literal{val=N} = Offset,
-                   true = Size > N,                    %Assertion.
-                   beam_types:get_tuple_element(N + 1, Es);
+               #{ Src := #t_tuple{size=Size,elements=Es} } when Offset < Size ->
+                   beam_types:get_tuple_element(Offset + 1, Es);
                #{} ->
                    any
            end,
diff --git a/lib/compiler/test/trycatch_SUITE.erl b/lib/compiler/test/trycatch_SUITE.erl
index 0c82f908b5..6221e64bcd 100644
--- a/lib/compiler/test/trycatch_SUITE.erl
+++ b/lib/compiler/test/trycatch_SUITE.erl
@@ -30,6 +30,7 @@
          stacktrace/1,nested_stacktrace/1,raise/1,
          no_return_in_try_block/1,
          expression_export/1,
+         throw_opt_crash/1,
          coverage/1]).
 
 -include_lib("common_test/include/ct.hrl").
@@ -48,6 +49,7 @@ groups() ->
        hockey,handle_info,catch_in_catch,grab_bag,
        stacktrace,nested_stacktrace,raise,
        no_return_in_try_block,expression_export,
+       throw_opt_crash,
        coverage]}].
 
 
@@ -1552,6 +1554,30 @@ expr_export_5() ->
         ok
     end.
 
+%% GH-4953: Type inference in throw optimization could crash in rare
+%% circumstances when a thrown type conflicted with one that was matched in
+%% a catch clause.
+throw_opt_crash(_Config) ->
+    try
+        throw_opt_crash_1(id(false), {pass, id(b), id(c)}),
+        throw_opt_crash_1(id(false), {crash, id(b)}),
+        ok
+    catch
+        throw:{pass, B, C} ->
+            {error, gurka, {B, C}};
+        throw:{beta, B, C} ->
+            {error, gaffel, {B, C}};
+        throw:{gamma, B, C} ->
+            {error, grammofon, {B, C}}
+    end.
+
+throw_opt_crash_1(true, {_, _ ,_}=Term) ->
+    throw(Term);
+throw_opt_crash_1(true, {_, _}=Term) ->
+    throw(Term);
+throw_opt_crash_1(false, _Term) ->
+    ok.
+
 coverage(_Config) ->
     {'EXIT',{{badfun,true},[_|_]}} = (catch coverage_1()),
     ok = coverage_ssa_throw(),
-- 
2.26.2

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