Update Android NDK and set optimization flags (#68354)

Brings in new cmake 2.23.1 and Android NDK23c which fixes an issue with the binary size and perf of libmonosgen-2.0.so

In NDK23b they decided to no longer pass -O2 compiler optimization flag (for arm64, armv7 used -Oz) as part of the Android toolchain but delegate to upstream CMake behavior: https://github.com/android/ndk/wiki/Changelog-r23 and https://github.com/android/ndk/issues/1536

CMake defaults to -O3 for Release builds but unfortunately this causes quite a noticable binary size increase and perf regression.

The Xamarin Android team measured startup time on an average of 10 runs of `dotnet new maui` on a Pixel 5:
```
-O3: 893.7ms
-O2: 600.2ms
-Oz: 649.1ms
```

We now explicitly pass in -O2 for Android builds.

Fixes https://github.com/dotnet/runtime/issues/68330

eng/native/build-commons.sh

@@ -84,8 +84,8 @@ build_native()
             exit 1
         fi
 
-        # keep ANDROID_NATIVE_API_LEVEL in sync with src/mono/Directory.Build.props
-        cmakeArgs="-DCMAKE_TOOLCHAIN_FILE=$ANDROID_NDK_ROOT/build/cmake/android.toolchain.cmake -DANDROID_NATIVE_API_LEVEL=21 $cmakeArgs"
+        # keep ANDROID_PLATFORM in sync with src/mono/Directory.Build.props
+        cmakeArgs="-DCMAKE_TOOLCHAIN_FILE=$ANDROID_NDK_ROOT/build/cmake/android.toolchain.cmake -DANDROID_PLATFORM=android-21 $cmakeArgs"
 
         # Don't try to set CC/CXX in init-compiler.sh - it's handled in android.toolchain.cmake already
         __Compiler="default"

eng/native/configureoptimization.cmake

@@ -12,6 +12,11 @@ if(CLR_CMAKE_HOST_WIN32)
 elseif(CLR_CMAKE_HOST_UNIX)
     add_compile_options($<$<CONFIG:Debug>:-O0>)
     add_compile_options($<$<CONFIG:Checked>:-O2>)
+    if(CLR_CMAKE_TARGET_ANDROID)
+        # -O2 optimization generates faster/smaller code on Android
+        add_compile_options($<$<CONFIG:Release>:-O2>)
+    else()
         add_compile_options($<$<CONFIG:Release>:-O3>)
+    endif()
     add_compile_options($<$<CONFIG:RelWithDebInfo>:-O2>)
 endif()

eng/pipelines/common/platform-matrix.yml

@@ -207,7 +207,7 @@ jobs:
       platform: Linux_bionic_arm64
       shouldContinueOnError: ${{ parameters.shouldContinueOnError }}
       container:
-        image: ubuntu-18.04-android-20220131172314-3983b4e
+        image: ubuntu-18.04-android-20220628174908-5789942
         registry: mcr
       jobParameters:
         runtimeFlavor: mono
@@ -236,7 +236,7 @@ jobs:
       platform: Linux_bionic_x64
       shouldContinueOnError: ${{ parameters.shouldContinueOnError }}
       container:
-        image: ubuntu-18.04-android-20220131172314-3983b4e
+        image: ubuntu-18.04-android-20220628174908-5789942
         registry: mcr
       jobParameters:
         runtimeFlavor: mono
@@ -494,7 +494,7 @@ jobs:
       platform: Android_x64
       shouldContinueOnError: ${{ parameters.shouldContinueOnError }}
       container:
-        image: ubuntu-18.04-android-20220131172314-3983b4e
+        image: ubuntu-18.04-android-20220628174908-5789942
         registry: mcr
       jobParameters:
         runtimeFlavor: mono
@@ -519,7 +519,7 @@ jobs:
       platform: Android_x86
       shouldContinueOnError: ${{ parameters.shouldContinueOnError }}
       container:
-        image: ubuntu-18.04-android-20220131172314-3983b4e
+        image: ubuntu-18.04-android-20220628174908-5789942
         registry: mcr
       jobParameters:
         runtimeFlavor: mono
@@ -544,7 +544,7 @@ jobs:
       platform: Android_arm
       shouldContinueOnError: ${{ parameters.shouldContinueOnError }}
       container:
-        image: ubuntu-18.04-android-20220131172314-3983b4e
+        image: ubuntu-18.04-android-20220628174908-5789942
         registry: mcr
       jobParameters:
         runtimeFlavor: mono
@@ -569,7 +569,7 @@ jobs:
       platform: Android_arm64
       shouldContinueOnError: ${{ parameters.shouldContinueOnError }}
       container:
-        image: ubuntu-18.04-android-20220131172314-3983b4e
+        image: ubuntu-18.04-android-20220628174908-5789942
         registry: mcr
       jobParameters:
         runtimeFlavor: mono

src/mono/CMakeLists.txt

@@ -314,6 +314,9 @@ elseif(TARGET_SYSTEM_NAME STREQUAL "Linux")
   set(TARGET_LINUX 1)
 elseif(TARGET_SYSTEM_NAME STREQUAL "Android")
   set(TARGET_ANDROID 1)
+  if (CMAKE_BUILD_TYPE STREQUAL "Release")
+    add_compile_options(-O2)
+  endif()
 elseif(TARGET_SYSTEM_NAME STREQUAL "Emscripten")
   set(TARGET_BROWSER 1)
   if (CMAKE_BUILD_TYPE STREQUAL "Release")

src/mono/Directory.Build.props

@@ -28,8 +28,8 @@
     <watchOS64_32Version></watchOS64_32Version>
     <macOSVersion></macOSVersion>
 
-    <!-- Version of the Android SDK we target, keep in sync with eng/native/build-commons.sh -->
-    <AndroidApiVersion>21</AndroidApiVersion>
+    <!-- Minimum version of the Android API level we target, keep in sync with eng/native/build-commons.sh -->
+    <AndroidApiLevelMin>21</AndroidApiLevelMin>
   </PropertyGroup>
 
   <!-- Output paths -->

src/mono/mono.proj

@@ -420,8 +420,7 @@
       <_MonoCMakeArgs Include="-DANDROID_NDK=$(ANDROID_NDK_ROOT)"/>
       <_MonoCMakeArgs Include="-DANDROID_STL=none"/>
       <_MonoCMakeArgs Include="-DANDROID_CPP_FEATURES=&quot;no-rtti no-exceptions&quot;"/>
-      <_MonoCMakeArgs Include="-DANDROID_NATIVE_API_LEVEL=$(AndroidApiVersion)"/>
-      <_MonoCMakeArgs Include="-DANDROID_PLATFORM=android-$(AndroidApiVersion)"/>
+      <_MonoCMakeArgs Include="-DANDROID_PLATFORM=android-$(AndroidApiLevelMin)"/>
       <_MonoCMakeArgs Condition="'$(Platform)' == 'arm64'" Include="-DANDROID_ABI=arm64-v8a" />
       <_MonoCMakeArgs Condition="'$(Platform)' == 'arm'" Include="-DANDROID_ABI=armeabi-v7a" />
       <_MonoCMakeArgs Condition="'$(Platform)' == 'x86'" Include="-DANDROID_ABI=x86" />

src/native/libs/CMakeLists.txt

@@ -103,8 +103,14 @@ if (CLR_CMAKE_TARGET_UNIX OR CLR_CMAKE_TARGET_BROWSER)
         if (CLR_CMAKE_TARGET_ARCH_ARMV7L AND DEFINED ENV{CROSSCOMPILE} AND CMAKE_C_COMPILER_VERSION VERSION_LESS 3.9)
             add_compile_options (-O1)
         else ()
+            if(CLR_CMAKE_TARGET_ANDROID)
+                # -O2 optimization generates faster/smaller code on Android
+                # TODO: This duplicates the settings in eng/native/configureoptimization.cmake, we should unify it
+                add_compile_options (-O2)
+            else()
                 add_compile_options (-O3)
             endif ()
+        endif ()
     else ()
         message(FATAL_ERROR "Unknown build type. Set CMAKE_BUILD_TYPE to DEBUG or RELEASE.")
     endif ()

src/tasks/AndroidAppBuilder/ApkBuilder.cs

@@ -334,7 +334,7 @@ public ApkBuilder(TaskLoggingHelper logger)
         File.WriteAllText(Path.Combine(OutputDir, "monodroid.c"), Utils.GetEmbeddedResource("monodroid.c"));
 
         string cmakeGenArgs = $"-DCMAKE_TOOLCHAIN_FILE={androidToolchain} -DANDROID_ABI=\"{abi}\" -DANDROID_STL=none " +
-            $"-DANDROID_NATIVE_API_LEVEL={MinApiLevel} -B monodroid";
+            $"-DANDROID_PLATFORM=android-{MinApiLevel} -B monodroid";
 
         string cmakeBuildArgs = "--build monodroid";