webrtc/system_wrappers/BUILD.gn
Alessio Bazzica 0441bb625f APM: add HW-only denormal disabler
Denormal numbers (see [1]) may origin in APM when the input is zeroed
after a non-zero signal. In extreme cases, instructions involving
denormal operands may run as much as 100 times slower, which seems to
be the case (to some extent) of crbug.com/1227566.

This CL adds a class that disables denormals only via hardware on x86
and on ARM. The class is used in APM and it is an adaption of [2].

Tested: appr.tc call on Chromium (Win, Mac)

[1] https://en.wikipedia.org/wiki/Denormal_number
[2] https://source.chromium.org/chromium/chromium/src/+/main:third_party/blink/renderer/platform/audio/denormal_disabler.h

Fixed: chromium:1227566
Change-Id: I0ed2eab55dc597529f09f93c26c7a01de051fdbe
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/227768
Reviewed-by: Magnus Flodman <mflodman@webrtc.org>
Reviewed-by: Per Åhgren <peah@webrtc.org>
Commit-Queue: Alessio Bazzica <alessiob@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#34701}
2021-08-10 15:48:22 +00:00

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# Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
#
# Use of this source code is governed by a BSD-style license
# that can be found in the LICENSE file in the root of the source
# tree. An additional intellectual property rights grant can be found
# in the file PATENTS. All contributing project authors may
# be found in the AUTHORS file in the root of the source tree.
if (is_android) {
import("//build/config/android/config.gni")
import("//build/config/android/rules.gni")
}
import("../webrtc.gni")
rtc_library("system_wrappers") {
visibility = [ "*" ]
sources = [
"include/clock.h",
"include/cpu_features_wrapper.h",
"include/cpu_info.h",
"include/ntp_time.h",
"include/rtp_to_ntp_estimator.h",
"include/sleep.h",
"source/clock.cc",
"source/cpu_features.cc",
"source/cpu_info.cc",
"source/rtp_to_ntp_estimator.cc",
"source/sleep.cc",
]
defines = []
libs = []
deps = [
":field_trial",
"../api:array_view",
"../api/units:timestamp",
"../modules:module_api_public",
"../rtc_base:checks",
"../rtc_base/synchronization:mutex",
"../rtc_base/system:arch",
"../rtc_base/system:rtc_export",
]
absl_deps = [ "//third_party/abseil-cpp/absl/types:optional" ]
if (is_android) {
if (build_with_mozilla) {
include_dirs = [
"/config/external/nspr",
"/nsprpub/lib/ds",
"/nsprpub/pr/include",
]
} else {
sources += [ "source/cpu_features_android.cc" ]
deps += [ "//third_party/android_sdk:cpu_features" ]
}
libs += [ "log" ]
}
if (is_linux || is_chromeos) {
if (!build_with_chromium) {
sources += [ "source/cpu_features_linux.cc" ]
}
libs += [ "rt" ]
}
if (is_win) {
libs += [ "winmm.lib" ]
# Windows needs ../rtc_base due to include of
# webrtc/rtc_base/win32.h in source/clock.cc.
deps += [ "../rtc_base:win32" ]
}
deps += [
"../rtc_base:rtc_base_approved",
"../rtc_base:rtc_numerics",
]
}
rtc_library("field_trial") {
visibility = [ "*" ]
public = [ "include/field_trial.h" ]
sources = [ "source/field_trial.cc" ]
if (rtc_exclude_field_trial_default) {
defines = [ "WEBRTC_EXCLUDE_FIELD_TRIAL_DEFAULT" ]
}
deps = [
"../rtc_base:checks",
"../rtc_base:logging",
"../rtc_base:stringutils",
]
absl_deps = [ "//third_party/abseil-cpp/absl/strings" ]
}
rtc_library("metrics") {
visibility = [ "*" ]
public = [ "include/metrics.h" ]
sources = [ "source/metrics.cc" ]
if (rtc_exclude_metrics_default) {
defines = [ "WEBRTC_EXCLUDE_METRICS_DEFAULT" ]
}
deps = [
"../rtc_base:checks",
"../rtc_base:rtc_base_approved",
"../rtc_base/synchronization:mutex",
]
}
rtc_library("denormal_disabler") {
visibility = [ "*" ]
public = [ "include/denormal_disabler.h" ]
sources = [ "source/denormal_disabler.cc" ]
deps = [
"../rtc_base:checks",
"../rtc_base/system:arch",
]
if (is_clang) {
cflags_cc = [ "-Wno-unused-private-field" ]
}
}
if (rtc_include_tests && !build_with_chromium) {
rtc_test("system_wrappers_unittests") {
testonly = true
sources = [
"source/clock_unittest.cc",
"source/denormal_disabler_unittest.cc",
"source/field_trial_unittest.cc",
"source/metrics_default_unittest.cc",
"source/metrics_unittest.cc",
"source/ntp_time_unittest.cc",
"source/rtp_to_ntp_estimator_unittest.cc",
]
deps = [
":denormal_disabler",
":field_trial",
":metrics",
":system_wrappers",
"../rtc_base:checks",
"../rtc_base:rtc_base_approved",
"../test:rtc_expect_death",
"../test:test_main",
"../test:test_support",
"//testing/gtest",
]
absl_deps = [ "//third_party/abseil-cpp/absl/strings" ]
if (is_android) {
deps += [ "//testing/android/native_test:native_test_support" ]
shard_timeout = 900
}
}
}