From 09f170e35cf9df8438ae42d48b51becff167b5b4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= <bjorn@erlang.org>
Date: Wed, 12 Oct 2016 08:00:22 +0200
Subject: compile_SUITE: Make sure that guards are optimized

Guards should use the more efficient 'test' instructions, not 'bif'
instructions. Add a test to make sure that the optimizations don't
degrade.

We do have to keep an exception list for functions where we can't
replace all 'bif' calls with 'test' instructions. We try to keep
that list a short as practically possible.
---
 lib/compiler/test/compile_SUITE.erl | 94 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 92 insertions(+), 2 deletions(-)

(limited to 'lib/compiler/test')

diff --git a/lib/compiler/test/compile_SUITE.erl b/lib/compiler/test/compile_SUITE.erl
index a2d3e2140b..e2988b18dc 100644
--- a/lib/compiler/test/compile_SUITE.erl
+++ b/lib/compiler/test/compile_SUITE.erl
@@ -32,7 +32,7 @@
 	 other_output/1, kernel_listing/1, encrypted_abstr/1,
 	 strict_record/1,
 	 cover/1, env/1, core/1,
-	 core_roundtrip/1, asm/1,
+	 core_roundtrip/1, asm/1, optimized_guards/1,
 	 sys_pre_attributes/1, dialyzer/1,
 	 warnings/1, pre_load_check/1, env_compiler_options/1
 	]).
@@ -49,7 +49,7 @@ all() ->
      binary, makedep, cond_and_ifdef, listings, listings_big,
      other_output, kernel_listing, encrypted_abstr,
      strict_record,
-     cover, env, core, core_roundtrip, asm,
+     cover, env, core, core_roundtrip, asm, optimized_guards,
      sys_pre_attributes, dialyzer, warnings, pre_load_check,
      env_compiler_options].
 
@@ -926,6 +926,96 @@ do_asm(Beam, Outdir) ->
 	    error
     end.
 
+%% Make sure that guards are fully optimized. Guards should
+%% should use 'test' instructions, not 'bif' instructions.
+
+optimized_guards(_Config) ->
+    TestBeams = get_unique_beam_files(),
+    test_lib:p_run(fun(F) -> do_opt_guards(F) end, TestBeams).
+
+do_opt_guards(Beam) ->
+    {ok,{M,[{abstract_code,{raw_abstract_v1,A}}]}} =
+	beam_lib:chunks(Beam, [abstract_code]),
+    try
+	{ok,M,Asm} = compile:forms(A, ['S']),
+	do_opt_guards_mod(Asm)
+    catch Class:Error ->
+	    io:format("~p: ~p ~p\n~p\n",
+		      [M,Class,Error,erlang:get_stacktrace()]),
+	    error
+    end.
+
+do_opt_guards_mod({Mod,_Exp,_Attr,Asm,_NumLabels}) ->
+    case do_opt_guards_fs(Mod, Asm) of
+	[] ->
+	    ok;
+	[_|_]=Bifs ->
+	    io:format("ERRORS FOR ~p:\n~p\n", [Mod,Bifs]),
+	    error
+    end.
+
+do_opt_guards_fs(Mod, [{function,Name,Arity,_,Is}|Fs]) ->
+    Bifs0 = do_opt_guards_fun(Is),
+
+    %% The compiler does not attempt to optimize 'xor'.
+    %% Therefore, ignore all functions that use 'xor' in
+    %% a guard.
+    Bifs = case lists:any(fun({bif,'xor',_,_,_}) -> true;
+			     (_) -> false
+			  end, Bifs0) of
+	       true -> [];
+	       false -> Bifs0
+	   end,
+
+    %% Filter out the allowed exceptions.
+    FA = {Name,Arity},
+    case {Bifs,is_exception(Mod, FA)} of
+	{[_|_],true} ->
+	    io:format("~p:~p/~p IGNORED:\n~p\n",
+		      [Mod,Name,Arity,Bifs]),
+	    do_opt_guards_fs(Mod, Fs);
+	{[_|_],false} ->
+	    [{FA,Bifs}|do_opt_guards_fs(Mod, Fs)];
+	{[],false} ->
+	    do_opt_guards_fs(Mod, Fs);
+	{[],true} ->
+	    io:format("Redundant exception for ~p:~p/~p\n",
+		      [Mod,Name,Arity]),
+	    error(redundant)
+    end;
+do_opt_guards_fs(_, []) -> [].
+
+do_opt_guards_fun([{bif,Name,{f,F},As,_}=I|Is]) when F =/= 0 ->
+    Arity = length(As),
+    case erl_internal:comp_op(Name, Arity) orelse
+	erl_internal:bool_op(Name, Arity) orelse
+	erl_internal:new_type_test(Name, Arity) of
+	true ->
+	    [I|do_opt_guards_fun(Is)];
+	false ->
+	    do_opt_guards_fun(Is)
+    end;
+do_opt_guards_fun([_|Is]) ->
+    do_opt_guards_fun(Is);
+do_opt_guards_fun([]) -> [].
+
+is_exception(bs_match_SUITE, {matching_and_andalso_2,2}) -> true;
+is_exception(bs_match_SUITE, {matching_and_andalso_3,2}) -> true;
+is_exception(guard_SUITE, {'-complex_not/1-fun-4-',1}) -> true;
+is_exception(guard_SUITE, {'-complex_not/1-fun-5-',1}) -> true;
+is_exception(guard_SUITE, {basic_andalso_orelse,1}) -> true;
+is_exception(guard_SUITE, {bad_guards,1}) -> true;
+is_exception(guard_SUITE, {bad_guards_2,2}) -> true;
+is_exception(guard_SUITE, {bad_guards_3,2}) -> true;
+is_exception(guard_SUITE, {cqlc,4}) -> true;
+is_exception(guard_SUITE, {csemi7,3}) -> true;
+is_exception(guard_SUITE, {misc,1}) -> true;
+is_exception(guard_SUITE, {nested_not_2b,4}) -> true;
+is_exception(guard_SUITE, {tricky_1,2}) -> true;
+is_exception(map_SUITE, {map_guard_update,2}) -> true;
+is_exception(map_SUITE, {map_guard_update_variables,3}) -> true;
+is_exception(_, _) -> false.
+
 sys_pre_attributes(Config) ->
     DataDir = proplists:get_value(data_dir, Config),
     File = filename:join(DataDir, "attributes.erl"),
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