File 1014-Remove-unsafe-optimization.patch of Package erlang

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File 1014-Remove-unsafe-optimization.patch of Package erlang (Revision e821d375830f7564cfd918f62d383b35)

Currently displaying revision e821d375830f7564cfd918f62d383b35 , Show latest

From e48897d427455ea8c2de19605f686af2ced4e47e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= <bjorn@erlang.org>
Date: Fri, 8 Mar 2024 12:56:15 +0100
Subject: [PATCH] Remove unsafe optimization

Replacing a `bs_start_match` instruction with an `is_bitstring/1`
instruction is unsafe if the source term is a match context.
---
 lib/compiler/src/beam_ssa_opt.erl    |  4 ----
 lib/compiler/test/bs_match_SUITE.erl | 31 ++++++++++++++++++++++++----
 2 files changed, 27 insertions(+), 8 deletions(-)

diff --git a/lib/compiler/src/beam_ssa_opt.erl b/lib/compiler/src/beam_ssa_opt.erl
index eadbb3cc2b..8f8e01a7ce 100644
--- a/lib/compiler/src/beam_ssa_opt.erl
+++ b/lib/compiler/src/beam_ssa_opt.erl
@@ -1381,10 +1381,6 @@ live_opt_is([#b_set{op={succeeded,guard},dst=SuccDst,args=[Dst]}=SuccI,
                 {bif,tuple_size} ->
                     I = I0#b_set{op={bif,is_tuple},dst=SuccDst},
                     live_opt_is([I|Is], Live0, Acc);
-                bs_start_match ->
-                    [#b_literal{val=new},Bin] = I0#b_set.args,
-                    I = I0#b_set{op={bif,is_bitstring},args=[Bin],dst=SuccDst},
-                    live_opt_is([I|Is], Live0, Acc);
                 get_map_element ->
                     I = I0#b_set{op=has_map_field,dst=SuccDst},
                     live_opt_is([I|Is], Live0, Acc);
diff --git a/lib/compiler/test/bs_match_SUITE.erl b/lib/compiler/test/bs_match_SUITE.erl
index e935fe98ff..fb2bcc0a74 100644
--- a/lib/compiler/test/bs_match_SUITE.erl
+++ b/lib/compiler/test/bs_match_SUITE.erl
@@ -49,7 +49,8 @@
          bad_phi_paths/1,many_clauses/1,
          combine_empty_segments/1,hangs_forever/1,
          bs_saved_position_units/1,empty_matches/1,
-         gh_6410/1]).
+         gh_6410/1,
+         otp_19019/1]).
 
 -export([coverage_id/1,coverage_external_ignore/2]).
 
@@ -89,7 +90,8 @@ groups() ->
        exceptions_after_match_failure,bad_phi_paths,
        many_clauses,combine_empty_segments,hangs_forever,
        bs_saved_position_units,empty_matches,
-       gh_6410]}].
+       gh_6410,
+       otp_19019]}].
 
 init_per_suite(Config) ->
     test_lib:recompile(?MODULE),
@@ -2672,6 +2674,25 @@ do_gh_6410(X) ->
             X
     end).
 
+otp_19019(_Config) ->
+    ok = do_otp_19019(id(<<42>>)),
+    <<>> = do_otp_19019(id(<<>>)),
+
+    ok.
+
+do_otp_19019(<<_:8>>) ->
+    ok;
+do_otp_19019(A) ->
+    try
+        %% The `bs_start_match` instruction would be replaced with an
+        %% `is_bitstring/1` test, which is not safe when `A` is a
+        %% match context.
+        << (ok) || <<_:ok>> <= A>>
+    after
+        ok
+    end.
+
+
 %%% Utilities.
 id(I) -> I.
 
-- 
2.35.3

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File 1014-Remove-unsafe-optimization.patch of Package erlang (Revision e821d375830f7564cfd918f62d383b35)

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