File 2171-compiler-Add-type-info-for-bs_init_writabl... of Package erlang

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File 2171-compiler-Add-type-info-for-bs_init_writable.patch of Package erlang

From 93ee923900c39caf367d9d96613c4b0b410dfb35 Mon Sep 17 00:00:00 2001
From: Frej Drejhammar <frej.drejhammar@gmail.com>
Date: Mon, 20 Jun 2022 10:24:16 +0200
Subject: [PATCH] compiler: Add type info for bs_init_writable

The SSA instruction bs_init_writable is not known to the SSA type
analysis pass, nor is its result type known to the BEAM
validator. This patch adds type information for bs_init_writable and
as it allows the SSA type pass to elide is_bitstring tests, it also
extends the BEAM validator to consider the result of bs_init_writable
to be a bitstring.
---
 lib/compiler/src/beam_ssa_type.erl            |  2 +
 lib/compiler/src/beam_validator.erl           |  3 ++
 lib/compiler/test/compile_SUITE.erl           | 20 ++++++++-
 .../compile_SUITE_data/bs_init_writable.erl   | 45 +++++++++++++++++++
 4 files changed, 68 insertions(+), 2 deletions(-)
 create mode 100644 lib/compiler/test/compile_SUITE_data/bs_init_writable.erl

diff --git a/lib/compiler/src/beam_ssa_type.erl b/lib/compiler/src/beam_ssa_type.erl
index f96d4c521e..c35ae6c717 100644
--- a/lib/compiler/src/beam_ssa_type.erl
+++ b/lib/compiler/src/beam_ssa_type.erl
@@ -2148,6 +2148,8 @@ type(update_tuple, [Src | Updates], _Anno, Ts, _Ds) ->
 type(wait_timeout, [#b_literal{val=infinity}], _Anno, _Ts, _Ds) ->
     %% Waits forever, never reaching the 'after' block.
     beam_types:make_atom(false);
+type(bs_init_writable, [_Size], _, _, _) ->
+    beam_types:make_type_from_value(<<>>);
 type(_, _, _, _, _) ->
     any.
 
diff --git a/lib/compiler/src/beam_validator.erl b/lib/compiler/src/beam_validator.erl
index 649382bd93..0323fd384c 100644
--- a/lib/compiler/src/beam_validator.erl
+++ b/lib/compiler/src/beam_validator.erl
@@ -3279,6 +3279,9 @@ join_tuple_elements(I, Tuple, Type0) ->
 call_types({extfunc,M,F,A}, A, Vst) ->
     Args = get_call_args(A, Vst),
     beam_call_types:types(M, F, Args);
+call_types(bs_init_writable, A, Vst) ->
+    T = beam_types:make_type_from_value(<<>>),
+    {T, get_call_args(A, Vst), false};
 call_types(_, A, Vst) ->
     {any, get_call_args(A, Vst), false}.
 
diff --git a/lib/compiler/test/compile_SUITE.erl b/lib/compiler/test/compile_SUITE.erl
index 648137259a..b2b3f65d6a 100644
--- a/lib/compiler/test/compile_SUITE.erl
+++ b/lib/compiler/test/compile_SUITE.erl
@@ -38,7 +38,7 @@
 	 warnings/1, pre_load_check/1, env_compiler_options/1,
          bc_options/1, deterministic_include/1, deterministic_paths/1,
          compile_attribute/1, message_printing/1, other_options/1,
-         transforms/1, erl_compile_api/1, types_pp/1
+         transforms/1, erl_compile_api/1, types_pp/1, bs_init_writable/1
 	]).
 
 suite() -> [{ct_hooks,[ts_install_cth]}].
@@ -58,7 +58,7 @@ all() ->
      env_compiler_options, custom_debug_info, bc_options,
      custom_compile_info, deterministic_include, deterministic_paths,
      compile_attribute, message_printing, other_options, transforms,
-     erl_compile_api, types_pp].
+     erl_compile_api, types_pp, bs_init_writable].
 
 groups() -> 
     [].
@@ -2063,6 +2063,22 @@ get_result_types([CallLine|Lines], TypeLine, Acc) ->
     [_,Callee,_] = string:split(CallLine, "`", all),
     get_result_types(Lines, Acc#{ Callee => TypeLine }).
 
+%% Check that the beam_ssa_type pass knows about bs_init_writable.
+bs_init_writable(Config) ->
+    DataDir = proplists:get_value(data_dir, Config),
+    PrivDir = proplists:get_value(priv_dir, Config),
+    InFile = filename:join(DataDir, "bs_init_writable.erl"),
+    OutDir = filename:join(PrivDir, "bs_init_writable"),
+    OutFile = filename:join(OutDir, "bs_init_writable.S"),
+    ok = file:make_dir(OutDir),
+    {ok,bs_init_writable} = compile:file(InFile, ['S',{outdir,OutDir}]),
+    {ok,Listing} = file:read_file(OutFile),
+    Os = [global,multiline,{capture,all_but_first,list}],
+    %% The is_bitstr test should be optimized away.
+    nomatch = re:run(Listing, "({test,is_bitstr,.+})", Os),
+    %% The is_bitstr test should be optimized away.
+    nomatch = re:run(Listing, "({test,is_binary,.+})", Os),
+    ok = file:del_dir_r(OutDir).
 
 
 %%%
diff --git a/lib/compiler/test/compile_SUITE_data/bs_init_writable.erl b/lib/compiler/test/compile_SUITE_data/bs_init_writable.erl
new file mode 100644
index 0000000000..a9e061645f
--- /dev/null
+++ b/lib/compiler/test/compile_SUITE_data/bs_init_writable.erl
@@ -0,0 +1,45 @@
+%%
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 2022. All Rights Reserved.
+%%
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%%
+%% %CopyrightEnd%
+%%
+
+-module(bs_init_writable).
+
+-export([do/0]).
+
+do() ->
+    Val = ex:foo(),
+    X = << <<B:1>> || B <- Val >>,
+    should_not_have_bitstring_test(X),
+    Y = << <<B:8>> || B <- Val >>,
+    should_not_have_binary_test(Y).
+
+
+%% If the beam_ssa_type pass does its job,
+%% should_not_have_bitstring_test/1 should not contain a is_bitstr test.
+should_not_have_bitstring_test(X) when is_bitstring(X) ->
+    bitstring;
+should_not_have_bitstring_test(_) ->
+    something_else.
+
+%% If the beam_ssa_type pass does its job,
+%% should_not_have_binary_test/1 should not contain a is_binary test.
+should_not_have_binary_test(X) when is_binary(X) ->
+    binary;
+should_not_have_binary_test(_) ->
+    something_else.
-- 
2.35.3

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File 2171-compiler-Add-type-info-for-bs_init_writable.patch of Package erlang

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