Support building libs and apps for iOS, watchOS, and tvOS with bitcode

build/config/ios/BUILD.gn

Index: build/config/ios/BUILD.gn
diff --git a/build/config/ios/BUILD.gn b/build/config/ios/BUILD.gn
index 0dda3e52631cc9f627d1e9519501859bafa6a7a2..ec6b9e67bcfb5f1fa5a7acb1495f5d4e6d7d8ac7 100644
--- a/build/config/ios/BUILD.gn
+++ b/build/config/ios/BUILD.gn
@@ -6,6 +6,23 @@ import("//build/config/ios/ios_sdk.gni")
 import("//build/config/sysroot.gni")
 import("//build/toolchain/toolchain.gni")
 
+declare_args() {
+  # Enabling this option makes clang compile to an intermediate
+  # representation ("bitcode"), and not to native code. This is preferred
+  # when including WebRTC in the apps that will be sent to Apple's App Store
+  # and mandatory for the apps that run on watchOS or tvOS.
+  # The option only works when building with Xcode (use_xcode_clang = true).
+  # Mimicking how Xcode handles it, the production builds (is_debug = false)
+  # get real bitcode sections added, while the debug builds (is_debug = true)
+  # only get bitcode-section "markers" added in them.
+  # NOTE: This option is ignored when building versions for the iOS simulator,
+  # where a part of libvpx is compiled from the assembly code written using
+  # Intel assembly syntax; Yasm / Nasm do not support emitting bitcode parts.
+  # That is not a limitation for now as Xcode mandates the presence of bitcode
+  # only when building bitcode-enabled projects for real devices (ARM CPUs).
+  enable_ios_bitcode = false
+}
+
 # This is included by reference in the //build/config/compiler:runtime_library
 # config that is applied to all targets. It is here to separate out the logic
 # that is iOS-only. Please see that target for advice on what should go in
@@ -24,6 +41,14 @@ config("runtime_library") {
     common_flags += [ "-miphoneos-version-min=$ios_deployment_target" ]
   }
 
+  if (use_xcode_clang && enable_ios_bitcode && !use_ios_simulator) {
+    if (is_debug) {
+      common_flags += [ "-fembed-bitcode-marker" ]
+    } else {
+      common_flags += [ "-fembed-bitcode" ]
+    }
+  }
+
   asmflags = common_flags
   cflags = common_flags
   ldflags = common_flags