[Task 1/5] [No QA] Add native PGO build and benchmark tooling

.gitignore

@@ -136,6 +136,9 @@ config/certificatePinning/roots/
 # Rspack build profiling output (RSPACK_PROFILE=OVERVIEW|ALL)
 .rspack-profile-*/
 
+# Local native PGO profiles
+.pgo/
+
 # Expo
 .expo
 dist/

android/app/build.gradle

@@ -84,6 +84,16 @@ project.ext.envConfigFiles = [
  * Set this to true to Run Proguard on Release builds to minify the Java bytecode.
  */
 def enableProguardInReleaseBuilds = true
+def pgoMode = providers.gradleProperty('pgoMode').getOrElse('off')
+def pgoProfile = providers.gradleProperty('pgoProfile').orNull
+
+if (!(pgoMode in ['off', 'generate', 'use'])) {
+    throw new GradleException("Unsupported pgoMode '${pgoMode}'. Use off, generate, or use.")
+}
+
+if (pgoMode == 'use' && !pgoProfile) {
+    throw new GradleException('pgoProfile is required when pgoMode=use.')
+}
 
 /**
  * The preferred build flavor of JavaScriptCore (JSC)
@@ -119,6 +129,7 @@ android {
         // Supported language variants must be declared here to avoid from being removed during the compilation.
         // This also helps us to not include unnecessary language variants in the APK.
         resConfigs "en", "es"
+        buildConfigField 'boolean', 'PGO_PROFILE_GENERATION', (pgoMode == 'generate').toString()
     }
 
     flavorDimensions "default"

android/app/src/main/AndroidManifest.xml

@@ -28,6 +28,14 @@
         android:theme="@style/AppTheme"
         tools:replace="android:supportsRtl">
 
+        <receiver
+            android:name=".PgoProfileReceiver"
+            android:exported="true">
+            <intent-filter>
+                <action android:name="com.expensify.chat.action.WRITE_PGO_PROFILES" />
+            </intent-filter>
+        </receiver>
+
         <service
             android:name="com.expensify.reactnativebackgroundtask.BackgroundJobService"
             android:permission="android.permission.BIND_JOB_SERVICE"

android/app/src/main/java/com/expensify/chat/PgoProfileReceiver.java

@@ -0,0 +1,27 @@
+package com.expensify.chat;
+
+import android.content.BroadcastReceiver;
+import android.content.Context;
+import android.content.Intent;
+import android.util.Log;
+
+/**
+ * Receives an explicit adb broadcast at the end of a local PGO collection run.
+ *
+ * The receiver is inert in ordinary builds. It deliberately lives outside the JS surface so a
+ * manual profiling journey can finish before its native counters are persisted.
+ */
+public final class PgoProfileReceiver extends BroadcastReceiver {
+    private static final String TAG = "PgoProfileReceiver";
+
+    @Override
+    public void onReceive(Context context, Intent intent) {
+        if (!BuildConfig.PGO_PROFILE_GENERATION) {
+            Log.w(TAG, "Ignoring PGO profile request in a non-instrumented build.");
+            return;
+        }
+
+        final int writtenProfiles = PgoProfileWriter.writeProfiles(context);
+        Log.i(TAG, "Wrote " + writtenProfiles + " LLVM PGO profile(s).");
+    }
+}

android/app/src/main/java/com/expensify/chat/PgoProfileWriter.java

@@ -0,0 +1,19 @@
+package com.expensify.chat;
+
+import android.content.Context;
+
+/** Development-only bridge for persisting LLVM PGO counters before Android kills the process. */
+public final class PgoProfileWriter {
+    private PgoProfileWriter() {}
+
+    private static native int writeProfiles(String directory);
+
+    public static int writeProfiles(Context context) {
+        if (!BuildConfig.PGO_PROFILE_GENERATION) {
+            return 0;
+        }
+
+        System.loadLibrary("ExpensifyNitroUtils");
+        return writeProfiles(context.getCacheDir().getAbsolutePath());
+    }
+}

ios/NewExpensify/RCTBootSplash.h

@@ -4,6 +4,7 @@
 
 + (void)initWithStoryboard:(NSString * _Nonnull)storyboardName
                   rootView:(UIView * _Nullable)rootView;
++ (void)initializePGOProfileCollection;
 + (void)hide:(BOOL)fade;
 + (void)bringSubviewToFrontIfInitialized;
 

ios/NewExpensify/RCTBootSplash.mm

@@ -13,13 +13,62 @@
 #import <React/RCTSurfaceHostingView.h>
 #import <React/RCTRootView.h>
 
+#ifndef EXPENSIFY_PGO_GENERATE
+#define EXPENSIFY_PGO_GENERATE 0
+#endif
+
+#if EXPENSIFY_PGO_GENERATE
+#include <dlfcn.h>
+
+extern "C" void __llvm_profile_set_filename(const char *FilenamePat);
+extern "C" int __llvm_profile_write_file(void);
+extern "C" void __llvm_profile_reset_counters(void);
+
+using PGOSetFilename = void (*)(const char *);
+using PGOWriteFile = int (*)();
+using PGOResetCounters = void (*)();
+
+template <typename Function>
+static Function HermesPGOFunction(const char *symbol) {
+  return reinterpret_cast<Function>(dlsym(RTLD_DEFAULT, symbol));
+}
+#endif
+
+static NSString *const PGO_DIRECTORY_NAME = @"ExpensifyPGO";
+static NSString *const PGO_STATUS_MARKER = @"profile-status.txt";
+static CFStringRef const PGO_WRITE_NOTIFICATION = CFSTR("com.expensify.pgo.write-profiles");
+static CFStringRef const PGO_CLEAR_NOTIFICATION = CFSTR("com.expensify.pgo.clear-profiles");
+
 static RCTSurfaceHostingProxyRootView *_rootView = nil;
 
 static UIView *_loadingView = nil;
 static NSMutableArray<RCTPromiseResolveBlock> *_resolveQueue = [[NSMutableArray alloc] init];
 static bool _fade = false;
 static bool _nativeHidden = false;
 
+static long long CurrentTimeMilliseconds(void) {
+  return (long long)([[NSDate date] timeIntervalSince1970] * 1000);
+}
+
+@interface RCTBootSplash ()
++ (NSURL *)pgoDirectoryURL;
++ (void)writePGOStatus:(NSString *)status result:(int)result;
++ (void)writePGOProfiles;
++ (void)clearPGOProfiles;
+@end
+
+static void HandlePGONotification(__unused CFNotificationCenterRef center,
+                                  __unused void *observer,
+                                  CFStringRef name,
+                                  __unused const void *object,
+                                  __unused CFDictionaryRef userInfo) {
+  if (CFEqual(name, PGO_WRITE_NOTIFICATION)) {
+    [RCTBootSplash writePGOProfiles];
+  } else if (CFEqual(name, PGO_CLEAR_NOTIFICATION)) {
+    [RCTBootSplash clearPGOProfiles];
+  }
+}
+
 @implementation RCTBootSplash
 
 RCT_EXPORT_MODULE();
@@ -32,6 +81,81 @@ + (BOOL)requiresMainQueueSetup {
   return NO;
 }
 
++ (NSURL *)pgoDirectoryURL {
+  NSURL *cachesURL = [[[NSFileManager defaultManager] URLsForDirectory:NSCachesDirectory
+                                                            inDomains:NSUserDomainMask] firstObject];
+  NSURL *directoryURL = [cachesURL URLByAppendingPathComponent:PGO_DIRECTORY_NAME isDirectory:YES];
+  [[NSFileManager defaultManager] createDirectoryAtURL:directoryURL
+                           withIntermediateDirectories:YES
+                                            attributes:nil
+                                                 error:nil];
+  return directoryURL;
+}
+
++ (void)writePGOStatus:(NSString *)status result:(int)result {
+  NSString *contents = [NSString stringWithFormat:@"%lld,%@,%d", CurrentTimeMilliseconds(), status, result];
+  NSURL *statusURL = [[self pgoDirectoryURL] URLByAppendingPathComponent:PGO_STATUS_MARKER];
+  [contents writeToURL:statusURL atomically:YES encoding:NSUTF8StringEncoding error:nil];
+}
+
++ (void)initializePGOProfileCollection {
+  static dispatch_once_t onceToken;
+  dispatch_once(&onceToken, ^{
+    CFNotificationCenterRef notificationCenter = CFNotificationCenterGetDarwinNotifyCenter();
+    CFNotificationCenterAddObserver(notificationCenter, NULL, HandlePGONotification, PGO_WRITE_NOTIFICATION, NULL, CFNotificationSuspensionBehaviorDeliverImmediately);
+    CFNotificationCenterAddObserver(notificationCenter, NULL, HandlePGONotification, PGO_CLEAR_NOTIFICATION, NULL, CFNotificationSuspensionBehaviorDeliverImmediately);
+
+#if EXPENSIFY_PGO_GENERATE
+    NSString *profilePattern = [[[self pgoDirectoryURL] URLByAppendingPathComponent:@"newdot-%m.profraw"] path];
+    __llvm_profile_set_filename(profilePattern.fileSystemRepresentation);
+    PGOSetFilename setHermesFilename = HermesPGOFunction<PGOSetFilename>("expensify_llvm_profile_set_filename");
+    if (setHermesFilename != nullptr) {
+      setHermesFilename(profilePattern.fileSystemRepresentation);
+    }
+#endif
+  });
+}
+
++ (void)writePGOProfiles {
+#if EXPENSIFY_PGO_GENERATE
+  int appResult = __llvm_profile_write_file();
+  PGOWriteFile writeHermesFile = HermesPGOFunction<PGOWriteFile>("expensify_llvm_profile_write_file");
+  int hermesResult = writeHermesFile != nullptr ? writeHermesFile() : 1;
+  int result = appResult == 0 && hermesResult == 0 ? 0 : 1;
+  [self writePGOStatus:@"written" result:result];
+  NSLog(@"ExpensifyPGO: wrote LLVM profile with result=%d appResult=%d hermesResult=%d", result, appResult, hermesResult);
+#else
+  [self writePGOStatus:@"not-instrumented" result:1];
+  NSLog(@"ExpensifyPGO: ignored profile write in a non-instrumented build");
+#endif
+}
+
++ (void)clearPGOProfiles {
+  NSFileManager *fileManager = [NSFileManager defaultManager];
+  NSURL *directoryURL = [self pgoDirectoryURL];
+  NSArray<NSURL *> *files = [fileManager contentsOfDirectoryAtURL:directoryURL
+                                      includingPropertiesForKeys:nil
+                                                         options:0
+                                                           error:nil];
+  for (NSURL *fileURL in files) {
+    if ([fileURL.lastPathComponent hasSuffix:@".profraw"] || [fileURL.lastPathComponent isEqualToString:PGO_STATUS_MARKER]) {
+      [fileManager removeItemAtURL:fileURL error:nil];
+    }
+  }
+
+#if EXPENSIFY_PGO_GENERATE
+  __llvm_profile_reset_counters();
+  PGOResetCounters resetHermesCounters = HermesPGOFunction<PGOResetCounters>("expensify_llvm_profile_reset_counters");
+  int result = resetHermesCounters != nullptr ? 0 : 1;
+  if (resetHermesCounters != nullptr) {
+    resetHermesCounters();
+  }
+  [self writePGOStatus:@"cleared" result:result];
+#else
+  [self writePGOStatus:@"not-instrumented" result:1];
+#endif
+}
+
 + (bool)isLoadingViewVisible {
   return _loadingView != nil && ![_loadingView isHidden];
 }

knip.json

@@ -90,5 +90,5 @@
         "diff-so-fancy",
         "@babel/plugin-proposal-class-properties"
     ],
-    "ignoreBinaries": ["metro-symbolicate", "mkcert", "openssl"]
+    "ignoreBinaries": ["metro-symbolicate", "mkcert", "openssl", "agent-device"]
 }

modules/ExpensifyNitroUtils/android/CMakeLists.txt

@@ -1,13 +1,42 @@
 project(ExpensifyNitroUtils)
+# cspell:ignore STREQUAL libclang fprofile defsym
+
 cmake_minimum_required(VERSION 3.9.0)
 
 set(PACKAGE_NAME ExpensifyNitroUtils)
 set(CMAKE_VERBOSE_MAKEFILE ON)
 set(CMAKE_CXX_STANDARD 20)
 
+if(EXPENSIFY_PGO_MODE STREQUAL "generate")
+    execute_process(
+        COMMAND ${CMAKE_CXX_COMPILER} --print-resource-dir
+        OUTPUT_VARIABLE CLANG_RESOURCE_DIR
+        OUTPUT_STRIP_TRAILING_WHITESPACE
+    )
+    set(PGO_RUNTIME "${CLANG_RESOURCE_DIR}/lib/linux/libclang_rt.profile-aarch64-android.a")
+    if(NOT EXISTS "${PGO_RUNTIME}")
+        message(FATAL_ERROR "LLVM profiling runtime was not found at ${PGO_RUNTIME}")
+    endif()
+    add_compile_options(-fprofile-generate)
+    add_link_options(
+        -fprofile-generate
+        "-Wl,--whole-archive,${PGO_RUNTIME},--no-whole-archive"
+        -Wl,--undefined=__llvm_profile_set_filename
+        -Wl,--undefined=__llvm_profile_write_file
+        -Wl,--defsym=expensify_llvm_profile_set_filename=__llvm_profile_set_filename
+        -Wl,--defsym=expensify_llvm_profile_write_file=__llvm_profile_write_file
+        -Wl,--export-dynamic-symbol=expensify_llvm_profile_set_filename
+        -Wl,--export-dynamic-symbol=expensify_llvm_profile_write_file
+    )
+elseif(EXPENSIFY_PGO_MODE STREQUAL "use")
+    add_compile_options("-fprofile-use=${EXPENSIFY_PGO_PROFILE}")
+    add_link_options("-fprofile-use=${EXPENSIFY_PGO_PROFILE}")
+endif()
+
 # Define C++ library and add all sources
 add_library(${PACKAGE_NAME} SHARED
     src/main/cpp/cpp-adapter.cpp
+    src/main/cpp/PgoProfileWriter.cpp
 )
 
 # Add Nitrogen specs
@@ -29,4 +58,4 @@ target_link_libraries(
     ${PACKAGE_NAME}
     ${LOG_LIB}
     android
-)
+)

modules/ExpensifyNitroUtils/android/build.gradle

@@ -34,6 +34,17 @@ def getExtOrIntegerDefault(name) {
   return rootProject.ext.has(name) ? rootProject.ext.get(name) : (project.properties["ExpensifyNitroUtils_" + name]).toInteger()
 }
 
+def pgoMode = rootProject.findProperty('pgoMode') ?: 'off'
+def pgoProfile = rootProject.findProperty('pgoProfile')
+
+if (!(pgoMode in ['off', 'generate', 'use'])) {
+  throw new GradleException("Unsupported pgoMode '${pgoMode}'. Use off, generate, or use.")
+}
+
+if (pgoMode == 'use' && !pgoProfile) {
+  throw new GradleException('pgoProfile is required when pgoMode=use.')
+}
+
 android {
   namespace "com.margelo.nitro.utils"
   ndkVersion getExtOrDefault("ndkVersion")
@@ -47,7 +58,10 @@ android {
     externalNativeBuild {
       cmake {
         cppFlags "-O2 -frtti -fexceptions -Wall -fstack-protector-all"
-        arguments "-DANDROID_STL=c++_shared"
+        arguments "-DANDROID_STL=c++_shared", "-DEXPENSIFY_PGO_MODE=${pgoMode}"
+        if (pgoMode == 'use') {
+          arguments "-DEXPENSIFY_PGO_PROFILE=${file(pgoProfile).absolutePath}"
+        }
         abiFilters (*reactNativeArchitectures())
       }
     }
@@ -126,4 +140,3 @@ dependencies {
   // Add a dependency on NitroModules
   implementation project(":react-native-nitro-modules")
 }
-