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cover: Use native coverage if supported
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Update the `cover` tool to use the native coverage feature of
the runtime system if supported by the runtime system.

I ran the compiler test with coverage on my M1 MacBook Pro both with
and without this commit. Here are running times:

* With this commit:    4 min 28 sec

* Without this commit: 5 min 34 sec
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@bjorng
bjorng committed Nov 21, 2023
1 parent 141a287 commit 5705b2a
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Showing 3 changed files with 111 additions and 47 deletions.
11 changes: 6 additions & 5 deletions lib/tools/doc/src/cover.xml
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Original file line number Diff line number Diff line change
Expand Up @@ -35,20 +35,21 @@
<description>
<p>The module <c>cover</c> provides a set of functions for coverage
analysis of Erlang programs, counting how many times each
<em>executable line</em> of code is executed when a program is run. <br></br>

<em>executable line</em> of code is executed when a program is run.
An executable line contains an Erlang expression such as a matching
or a function call. A blank line or a line containing a comment,
function head or pattern in a <c>case</c>- or <c>receive</c> statement
function head or pattern in a <c>case</c> or <c>receive</c> statement
is not executable.</p>
<p>Coverage analysis can be used to verify test cases, making sure all
relevant code is covered, and may also be helpful when looking for
bottlenecks in the code.</p>
<p>Before any analysis can take place, the involved modules must be
<em>Cover compiled</em>. This means that some extra information is
<em>cover compiled</em>. This means that some extra information is
added to the module before it is compiled into a binary which then
is loaded. The source file of the module is not affected and no
<c>.beam</c> file is created.</p>
<c>.beam</c> file is created. If the runtime system supports coverage
natively, Cover will automatically use that functionality to lower the
execution overhead for cover-compiled code.</p>
<p>Each time a function in a Cover compiled module is called,
information about the call is added to an internal database of Cover.
The coverage analysis is performed by examining the contents of
Expand Down
139 changes: 99 additions & 40 deletions lib/tools/src/cover.erl
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Original file line number Diff line number Diff line change
Expand Up @@ -1254,7 +1254,7 @@ do_start_nodes(Nodes, State) ->
{_LoadedModules,Compiled} =
get_compiled_still_loaded(State#main_state.nodes,
State#main_state.compiled),
remote_load_compiled(StartedNodes,Compiled),
remote_load_compiled(StartedNodes, Compiled, State),

State1 =
State#main_state{nodes = State#main_state.nodes ++ StartedNodes,
Expand Down Expand Up @@ -1303,7 +1303,7 @@ sync_compiled(Node,State) ->
remote_unload([Node],Unload),
Load = [L || L <- Compiled,
false == lists:member(L,RemoteCompiled)],
remote_load_compiled([Node],Load),
remote_load_compiled([Node], Load, State),
State#main_state{compiled=Compiled, nodes=[Node|Nodes]}
end,
State1#main_state{lost_nodes=Lost--[Node]}.
Expand All @@ -1312,8 +1312,14 @@ sync_compiled(Node,State) ->
%% We do it ?MAX_MODS modules at a time so that we don't
%% run out of memory on the cover_server node.
-define(MAX_MODS, 10).
remote_load_compiled(Nodes,Compiled) ->
remote_load_compiled(Nodes, Compiled, [], 0).
remote_load_compiled(Nodes, Compiled, #main_state{local_only=LocalOnly}) ->
case LocalOnly of
true ->
ok;
false ->
remote_load_compiled(Nodes, Compiled, [], 0)
end.

remote_load_compiled(_Nodes, [], [], _ModNum) ->
ok;
remote_load_compiled(Nodes, Compiled, Acc, ModNum)
Expand Down Expand Up @@ -1624,7 +1630,7 @@ do_compile_beams(ModsAndFiles, State) ->
end,
ModsAndFiles),
Compiled = [{M,F} || {ok,M,F} <- Result0],
remote_load_compiled(State#main_state.nodes,Compiled),
remote_load_compiled(State#main_state.nodes, Compiled, State),
fix_state_and_result(Result0,State,[]).

do_compile_beam(Module,BeamFile0,State) ->
Expand Down Expand Up @@ -1665,7 +1671,7 @@ do_compile(Files, Options, State) ->
end,
Files),
Compiled = [{M,F} || {ok,M,F} <- Result0],
remote_load_compiled(State#main_state.nodes,Compiled),
remote_load_compiled(State#main_state.nodes, Compiled, State),
fix_state_and_result(Result0,State,[]).

do_compile1(File, Options, LocalOnly) ->
Expand Down Expand Up @@ -1741,7 +1747,9 @@ do_compile_beam2(Module,Beam,UserOptions,Forms0,MainFile,LocalOnly) ->
%% Compile and load the result.
%% It's necessary to check the result of loading since it may
%% fail, for example if Module resides in a sticky directory.
Options = SourceInfo ++ UserOptions,
Options0 = SourceInfo ++ UserOptions,
Options = [report_errors,force_line_counters|Options0],

{ok, Module, Binary} = compile:forms(Forms, Options),

case code:load_binary(Module, ?TAG, Binary) of
Expand Down Expand Up @@ -1810,10 +1818,15 @@ counter_index(Mod, F, A, C, Line) ->

%% Create the counter array and store as a persistent term.
maybe_create_counters(Mod, true) ->
Cref = create_counters(Mod),
Key = {?MODULE,Mod},
persistent_term:put(Key, Cref),
ok;
case has_native_coverage() of
false ->
Cref = create_counters(Mod),
Key = {?MODULE,Mod},
persistent_term:put(Key, Cref),
ok;
true ->
ok
end;
maybe_create_counters(_Mod, false) ->
ok.

Expand All @@ -1824,14 +1837,20 @@ create_counters(Mod) ->
ets:insert(?COVER_MAPPING_TABLE, {{counters,Mod},Cref}),
Cref.

patch_code(Mod, Forms, false) ->
A = erl_anno:new(0),
AbstrKey = {tuple,A,[{atom,A,?MODULE},{atom,A,Mod}]},
patch_code1(Forms, {distributed,AbstrKey});
patch_code(Mod, Forms, true) ->
Cref = create_counters(Mod),
AbstrCref = cid_to_abstract(Cref),
patch_code1(Forms, {local_only,AbstrCref}).
patch_code(Mod, Forms, Local) ->
case has_native_coverage() of
true ->
_ = catch code:reset_coverage(Mod),
Forms;
false when Local =:= false ->
A = erl_anno:new(0),
AbstrKey = {tuple,A,[{atom,A,?MODULE},{atom,A,Mod}]},
patch_code1(Forms, {distributed,AbstrKey});
false when Local =:= true ->
Cref = create_counters(Mod),
AbstrCref = cid_to_abstract(Cref),
patch_code1(Forms, {local_only,AbstrCref})
end.

%% Go through the abstract code and replace 'executable_line' forms
%% with the actual code to increment the counters.
Expand Down Expand Up @@ -1885,30 +1904,37 @@ send_counters(Mod, CollectorPid) ->
%% Called on the main node. Collect the counters and consolidate
%% them into the collection table. Also zero the counters.
move_counters(Mod) ->
move_counters(Mod, fun insert_in_collection_table/1).
Process = fun insert_in_collection_table/1,
move_counters(Mod, Process).

move_counters(Mod, Process) ->
Move = case has_native_coverage() of
true ->
native_move(Mod);
false ->
standard_move(Mod)
end,
Pattern = {#bump{module=Mod,_='_'},'_'},
Matches = ets:match_object(?COVER_MAPPING_TABLE, Pattern, ?CHUNK_SIZE),
Cref = get_counters_ref(Mod),
move_counters1(Matches, Cref, Process).
move_counters1(Matches, Move, Process).

move_counters1({Mappings,Continuation}, Cref, Process) ->
Move = fun({Key,Index}) ->
Count = counters:get(Cref, Index),
ok = counters:sub(Cref, Index, Count),
{Key,Count}
end,
Process(lists:map(Move, Mappings)),
move_counters1(ets:match_object(Continuation), Cref, Process);
move_counters1('$end_of_table', _Cref, _Process) ->
move_counters1({Mappings,Continuation}, Move, Process) ->
Moved = [Move(Item) || Item <- Mappings],
Process(Moved),
move_counters1(ets:match_object(Continuation), Move, Process);
move_counters1('$end_of_table', _Move, _Process) ->
ok.

counters_mapping_table(Mod) ->
Mapping = counters_mapping(Mod),
Cref = get_counters_ref(Mod),
#{size:=Size} = counters:info(Cref),
[{Mod,Size}|Mapping].
case has_native_coverage() of
false ->
Cref = get_counters_ref(Mod),
#{size:=Size} = counters:info(Cref),
[{Mod,Size}|Mapping];
true ->
Mapping
end.

get_counters_ref(Mod) ->
ets:lookup_element(?COVER_MAPPING_TABLE, {counters,Mod}, 2).
Expand All @@ -1924,14 +1950,44 @@ clear_counters(Mod) ->
_ = ets:match_delete(?COVER_MAPPING_TABLE, Pattern),
ok.

standard_move(Mod) ->
Cref = get_counters_ref(Mod),
fun({Key,Index}) ->
Count = counters:get(Cref, Index),
ok = counters:sub(Cref, Index, Count),
{Key,Count}
end.

native_move(Mod) ->
Coverage = maps:from_list(code:get_coverage(line, Mod)),
_ = code:reset_coverage(Mod),
fun({#bump{line=Line}=Key,_Index}) ->
case Coverage of
#{Line := false} ->
{Key,0};
#{Line := true} ->
{Key,1};
#{Line := N} when is_integer(N), N >= 0 ->
{Key,N};
#{} ->
{Key,0}
end
end.

%% Reset counters (set counters to 0).
reset_counters(Mod) ->
Pattern = {#bump{module=Mod,_='_'},'$1'},
MatchSpec = [{Pattern,[],['$1']}],
Matches = ets:select(?COVER_MAPPING_TABLE,
MatchSpec, ?CHUNK_SIZE),
Cref = get_counters_ref(Mod),
reset_counters1(Matches, Cref).
case has_native_coverage() of
true ->
_ = catch code:reset_coverage(Mod),
ok;
false ->
Pattern = {#bump{module=Mod,_='_'},'$1'},
MatchSpec = [{Pattern,[],['$1']}],
Matches = ets:select(?COVER_MAPPING_TABLE,
MatchSpec, ?CHUNK_SIZE),
Cref = get_counters_ref(Mod),
reset_counters1(Matches, Cref)
end.

reset_counters1({Indices,Continuation}, Cref) ->
_ = [counters:put(Cref, N, 0) || N <- Indices],
Expand Down Expand Up @@ -2610,3 +2666,6 @@ html_encoding(latin1) ->
"iso-8859-1";
html_encoding(utf8) ->
"utf-8".

has_native_coverage() ->
code:coverage_support().
8 changes: 6 additions & 2 deletions lib/tools/src/tools.app.src
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Original file line number Diff line number Diff line change
Expand Up @@ -41,7 +41,11 @@
{env, [{file_util_search_methods,[{"", ""}, {"ebin", "esrc"}, {"ebin", "src"}]}
]
},
{runtime_dependencies, ["stdlib-4.0","runtime_tools-1.8.14",
"kernel-6.0","erts-9.1","compiler-5.0", "erts-13.0"]}
{runtime_dependencies, ["stdlib-@OTP-18856@",
"runtime_tools-@OTP-18856@",
"kernel-@OTP-18856@",
"erts-@OTP-18856@",
"compiler-@OTP-18856@",
"erts-@OTP-18856@"]}
]
}.

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