File 0438-Correct-bug-in-CSE-optimization.patch of Package erlang

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File 0438-Correct-bug-in-CSE-optimization.patch of Package erlang (Revision cb0c7ad891d5307a2eb53842d7d69a0f)

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From a874fbc4893cd253e708cfc06b71f04a5c38e4eb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= <bjorn@erlang.org>
Date: Sun, 31 Jul 2022 13:49:47 +0200
Subject: [PATCH] Correct bug in CSE optimization

The expression:

#{assoc := V} = #{key => self()}, V.

is supposed to raise a `badmatch` exception, but because of an
overeager common subexpression elimination optimization, it
returned `#{}`.
---
 lib/compiler/src/beam_ssa_opt.erl |  2 +-
 lib/compiler/test/map_SUITE.erl   | 33 +++++++++++++++++++++++++++++--
 2 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/lib/compiler/src/beam_ssa_opt.erl b/lib/compiler/src/beam_ssa_opt.erl
index 261a751880..4533b5b2ef 100644
--- a/lib/compiler/src/beam_ssa_opt.erl
+++ b/lib/compiler/src/beam_ssa_opt.erl
@@ -1005,7 +1005,7 @@ cse_add_inferred_exprs(#b_set{op={bif,tl},dst=Tl,args=[List]}, Es) ->
     Es#{{get_tl,[List]} => Tl};
 cse_add_inferred_exprs(#b_set{op={bif,map_get},dst=Value,args=[Key,Map]}, Es) ->
     Es#{{get_map_element,[Map,Key]} => Value};
-cse_add_inferred_exprs(#b_set{op=put_map,dst=Map,args=Args}, Es) ->
+cse_add_inferred_exprs(#b_set{op=put_map,dst=Map,args=[_,_|Args]}, Es) ->
     cse_add_map_get(Args, Map, Es);
 cse_add_inferred_exprs(_, Es) -> Es.
 
diff --git a/lib/compiler/test/map_SUITE.erl b/lib/compiler/test/map_SUITE.erl
index 6269851e85..aec95f1e6d 100644
--- a/lib/compiler/test/map_SUITE.erl
+++ b/lib/compiler/test/map_SUITE.erl
@@ -77,7 +77,10 @@
         t_duplicate_keys/1,
 
         %% new in OTP 23
-        t_key_expressions/1
+        t_key_expressions/1,
+
+         %% miscellaneous
+         t_cse_assoc/1
     ]).
 
 suite() -> [].
@@ -138,7 +141,10 @@ all() ->
         t_duplicate_keys,
 
         %% new in OTP 23
-        t_key_expressions
+        t_key_expressions,
+
+     %% miscellaneous
+     t_cse_assoc
     ].
 
 groups() -> [].
@@ -2350,6 +2356,29 @@ dup_keys_1(Map) ->
             O2
     end.
 
+t_cse_assoc(_Config) ->
+    {'EXIT',{{case_clause,#{key:=any}},_}} = catch do_cse_assoc(id(any)),
+
+    {'EXIT',{{case_clause,#{key:=value}},_}} = catch do_cse_assoc(id(#{}), id(value)),
+    42 = do_cse_assoc(id(#{assoc => 42}), id(any)),
+
+    ok.
+
+do_cse_assoc(V) ->
+    case #{key => V} of
+        #{assoc := Assoc} ->
+            %% The CSE optimization would consider the first two arguments in
+            %% the argument for `put_map` to be the key `alloc` and the value
+            %% `#{}`.
+            Assoc
+    end.
+
+do_cse_assoc(M, V) ->
+    case M#{key => V} of
+        #{assoc := Assoc} ->
+            Assoc
+    end.
+
 %% aux
 
 rand_terms(0) -> [];
-- 
2.35.3

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File 0438-Correct-bug-in-CSE-optimization.patch of Package erlang (Revision cb0c7ad891d5307a2eb53842d7d69a0f)

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