（基于android12分析和測試）

一、現存問題

Android早期是aot的方式先編譯成機器碼，然后再運行的，這樣會導致安裝時間變長，后面的版本改成jit編譯方式休建，在運行時編譯乍恐，這樣會導致運行速度較慢。android7.0之后的版本支持jit+oat的方式編譯测砂，支持app配置baseline-profile的方式設置熱點代碼茵烈。

二、理論基礎

1砌些、ART 執(zhí)行方式

1. 最初安裝應用時不進行任何 AOT 編譯呜投。應用前幾次運行時，系統(tǒng)會對其進行解譯存璃，并對經常執(zhí)行的方法進行 JIT 編譯仑荐。
2. 當設備閑置和充電時，編譯守護程序會運行纵东，以便根據在應用前幾次運行期間生成的配置文件對常用代碼進行 AOT 編譯粘招。

3. 下一次重新啟動應用時將會使用配置文件引導型代碼，并避免在運行時對已經過編譯的方法進行 JIT 編譯偎球。在應用后續(xù)運行期間經過 JIT 編譯的方法將會添加到配置文件中洒扎，然后編譯守護程序將會對這些方法進行 AOT 編譯。

   
   
   1695197336986.png

2衰絮、編譯選項

dex2oat工具可以將dex文件生成vdex袍冷，odex或者.art文件。其中：

1. .dex
   .java->.class->.dex （apk解壓后的問題）
   java被編譯成.class之后猫牡，使用d8工具（以前是dx）將class文件合成dex文件胡诗，dex一般是jar的50%大小。然后被打包成單個 .apk 文件。.dex 文件可以通過自動轉換用 Java 編程語言編寫的編譯應用程序來創(chuàng)建乃戈。

2. .odex一種文件格式
   .java->.class->.dex->.oat
   過 AOT 編譯的方法代碼,ART可以直接用的機器碼褂痰。

3. .vdex
   dex->.vdex
   對dex文件進行初步優(yōu)化，調用dexOpt方法症虑，轉成vdex文件（文件名后綴依然是.dex）缩歪，只是小小的優(yōu)化了操作碼，
   其中odex的文件是可以直接被運行的谍憔。生成那種類型的文件依賴dex2Oat工具匪蝙，dex2Oat依賴一個核心參數“編譯過濾器”

編譯過濾器：(android 官方sdk android8.0之后沒有再更新)

• verify：僅運行 DEX 代碼驗證。
• quicken：（從 Android 12 開始已移除）運行 DEX 代碼驗證习贫，并優(yōu)化一些 DEX 指令逛球，以獲得更好的解譯器性能。（我在12還是看到有這樣配置）
• speed：運行 DEX 代碼驗證苫昌，并對所有方法進行 AOT 編譯颤绕。
• speed-profile：運行 DEX 代碼驗證，并對配置文件中列出的方法進行 AOT 編譯祟身。

實際上最新的android 12代碼中增加了一些奥务。

//android_12/art/libartbase/base/compiler_filter.h
enum Filter {
  kAssumeVerified,      // Skip verification but mark all classes as verified anyway.
  kExtract,             // Delay verication to runtime, do not compile anything.
  kVerify,              // Only verify classes.
  kSpaceProfile,        // Maximize space savings based on profile.
  kSpace,               // Maximize space savings.
  kSpeedProfile,        // Maximize runtime performance based on profile.
  kSpeed,               // Maximize runtime performance.
  kEverythingProfile,   // Compile everything capable of being compiled based on profile.
  kEverything,          // Compile everything capable of being compiled.
};
 
 
 
//android_12/art/libartbase/base/compiler_filter.cc
std::string CompilerFilter::NameOfFilter(Filter filter) {
  switch (filter) {
    case CompilerFilter::kAssumeVerified: return "assume-verified";
    case CompilerFilter::kExtract: return "extract";
    case CompilerFilter::kVerify: return "verify";
    case CompilerFilter::kSpaceProfile: return "space-profile";
    case CompilerFilter::kSpace: return "space";
    case CompilerFilter::kSpeedProfile: return "speed-profile";
    case CompilerFilter::kSpeed: return "speed";
    case CompilerFilter::kEverythingProfile: return "everything-profile";
    case CompilerFilter::kEverything: return "everything";
  }
  UNREACHABLE();
}

從這里可以得知，quicken被移除了袜硫，如果配置了重定向到verify 氯葬。配置speed可以將所有方法進行oat，從而加速代碼的運行速度婉陷。配置speed-profile帚称，可以選擇性的讓配置的方法進行AOT編譯。

3秽澳、強制編譯命令

系統(tǒng)支持用命令執(zhí)行odex編譯

命令：

adb shell cmd package compile

基于配置文件：

adb shell cmd package compile -m speed-profile -f my-package

全面編譯：

adb shell cmd package compile -m speed -f my-package

代碼執(zhí)行流程 ：

1695197534122.png

命令執(zhí)行后會生成odex和vdex文件闯睹，放置在data/app/package/oat/arm[64]/xxx

重啟進程后可以使用命令查：

/proc/pid/maps/ |grep "odex"

這樣就看到應用加載了odex加載到了內存。

4担神、手動執(zhí)行dex2Oat

android系統(tǒng)是自帶dex2oat工具的瞻坝，直接在平臺執(zhí)行dex2oat 命令可以直接生成對應的文件，默認位speed編譯

dex2oat --dex-file=a.dex --oat-file=./oat/arm64/base.odex

不過我企圖生成odex去覆蓋原來的odex失敗了杏瞻。簡單看了ART執(zhí)行的邏輯所刀，應該是校驗不通過導致。（沒有仔細研究捞挥，只是簡單看看代碼+推測）浮创。

后面發(fā)現如果用PackageManagerService（pkms）去生成一個odex就可以用。于是我加了點log查看一樣的命令參數砌函，使用pkms同款編譯參數后就可以用了斩披。放上研究了一天的命令參數

dex2oat32 --dex-file=./data/app/xxx/xxx.dex --oat-file=/data/app/xxx/oat/arm/xxx.odex --classpath-dir=/data/app/xxx --class-loader-context=PCL[]{PCL[/system/framework/org.apache.http.legacy.jar]} --instruction-set=arm --instruction-set-features=default --instruction-set-variant=cortex-a7 --compiler-filter=speed --compilation-reason=cmdline --max-image-block-size=524288 --resolve-startup-const-strings=true --generate-mini-debug-info --runtime-arg -Xdeny-art-apex-data-files  --runtime-arg -Xtarget-sdk-version:31 --runtime-arg -Xhidden-api-policy:enabled -j4 --runtime-arg -Xms64m --runtime-arg -Xmx512m --compile-individually

三溜族、PKMS 代碼執(zhí)行邏輯

1、pkms執(zhí)行邏輯

1695200019816.png

int performDexOpt(AndroidPackage pkg, @NonNull PackageSetting pkgSetting,
        String[] instructionSets, CompilerStats.PackageStats packageStats,
        PackageDexUsage.PackageUseInfo packageUseInfo, DexoptOptions options) {
 
    if (PLATFORM_PACKAGE_NAME.equals(pkg.getPackageName())) {
        throw new IllegalArgumentException("System server dexopting should be done via "
                + " DexManager and PackageDexOptimizer#dexoptSystemServerPath");
    }
    if (pkg.getUid() == -1) {
        throw new IllegalArgumentException("Dexopt for " + pkg.getPackageName()
                + " has invalid uid.");
    }
    if (!canOptimizePackage(pkg)) {//過濾不允許oat的
        return DEX_OPT_SKIPPED;
    }
    synchronized (mInstallLock) {
        final long acquireTime = acquireWakeLockLI(pkg.getUid());
        try {
            return performDexOptLI(pkg, pkgSetting, instructionSets,
                    packageStats, packageUseInfo, options);
        } finally {
            releaseWakeLockLI(acquireTime);
        }
    }
}
 
// 進入performDexOptLI(pkg, pkgSetting, instructionSets, packageStats, packageUseInfo, options)
 
private int performDexOptLI(AndroidPackage pkg, @NonNull PackageSetting pkgSetting,
        String[] targetInstructionSets, CompilerStats.PackageStats packageStats,
        PackageDexUsage.PackageUseInfo packageUseInfo, DexoptOptions options) {
...
 
    int result = DEX_OPT_SKIPPED;
    for (int i = 0; i < paths.size(); i++) {
        // Skip paths that have no code.
        if (!pathsWithCode[i]) {
            continue;
        }
        if (classLoaderContexts[i] == null) {
            throw new IllegalStateException("Inconsistent information in the "
                    + "package structure. A split is marked to contain code "
                    + "but has no dependency listed. Index=" + i + " path=" + paths.get(i));
        }
 
        // Append shared libraries with split dependencies for this split.
        String path = paths.get(i);
        if (options.getSplitName() != null) {
            // We are asked to compile only a specific split. Check that the current path is
            // what we are looking for.
            if (!options.getSplitName().equals(new File(path).getName())) {
                continue;
            }
        }
 
        String profileName = ArtManager.getProfileName(
                i == 0 ? null : pkg.getSplitNames()[i - 1]); //找profile文件
 
        ...
 
        final String compilerFilter = getRealCompilerFilter(pkg,
            options.getCompilerFilter(), isUsedByOtherApps);//對一些過濾編譯器做調整
        ...
 
        for (String dexCodeIsa : dexCodeInstructionSets) {
            int newResult = dexOptPath(pkg, pkgSetting, path, dexCodeIsa, compilerFilter,
                    profileAnalysisResult, classLoaderContexts[i], dexoptFlags, sharedGid,
                    packageStats, options.isDowngrade(), profileName, dexMetadataPath,
                    options.getCompilationReason());
        ...
    return result;
}
 
//進入dexOptPath
 
private int dexOptPath(AndroidPackage pkg, @NonNull PackageSetting pkgSetting, String path,
        String isa, String compilerFilter, int profileAnalysisResult, String classLoaderContext,
        int dexoptFlags, int uid, CompilerStats.PackageStats packageStats, boolean downgrade,
        String profileName, String dexMetadataPath, int compilationReason) {
   ...
    String oatDir = getPackageOatDirIfSupported(pkg,
            pkgSetting.getPkgState().isUpdatedSystemApp());
 
    ...
        mInstaller.dexopt(path, uid, pkg.getPackageName(), isa, dexoptNeeded, oatDir,
                dexoptFlags, compilerFilter, pkg.getVolumeUuid(), classLoaderContext,
                seInfo, false /* downgrade*/, pkg.getTargetSdkVersion(),
                profileName, dexMetadataPath,
                getAugmentedReasonName(compilationReason, dexMetadataPath != null)); //調用Installer 執(zhí)行dexOpt過程
 
        ...
        return DEX_OPT_PERFORMED;
    } catch (InstallerException e) {
        Slog.w(TAG, "Failed to dexopt", e);
        return DEX_OPT_FAILED;
    }
}

調用performDexOpt需要傳入以下參數

performDexOpt(AndroidPackage pkg, @NonNull PackageSetting pkgSetting,

String[] instructionSets,

CompilerStats.PackageStats packageStats,

PackageDexUsage.PackageUseInfo packageUseInfo,

DexoptOptions options)

其中DexoptOptions 定義了編譯的可選項垦沉，其構造方法如下煌抒，有個比較重要的屬性compilationReason，構造方法2也是通過reason獲取compilerFilter的厕倍。

//構造1
public DexoptOptions(String packageName, String compilerFilter, int flags) {
    this(packageName, /*compilationReason*/ -1, compilerFilter, /*splitName*/ null, flags);
}
 
//構造2
public DexoptOptions(String packageName, int compilationReason, int flags) {
    this(packageName, compilationReason, getCompilerFilterForReason(compilationReason),
            /*splitName*/ null, flags);
}
 
//構造3
public DexoptOptions(String packageName, int compilationReason, String compilerFilter,
            String splitName, int flags) {
    int validityMask =
            DEXOPT_CHECK_FOR_PROFILES_UPDATES |
            DEXOPT_FORCE |
            DEXOPT_BOOT_COMPLETE |
            DEXOPT_ONLY_SECONDARY_DEX |
            DEXOPT_ONLY_SHARED_DEX |
            DEXOPT_DOWNGRADE |
            DEXOPT_AS_SHARED_LIBRARY |
            DEXOPT_IDLE_BACKGROUND_JOB |
            DEXOPT_INSTALL_WITH_DEX_METADATA_FILE |
            DEXOPT_FOR_RESTORE;
    if ((flags & (~validityMask)) != 0) {
        throw new IllegalArgumentException("Invalid flags : " + Integer.toHexString(flags));
    }
 
    mPackageName = packageName;
    mCompilerFilter = compilerFilter;
    mFlags = flags;
    mSplitName = splitName;
    mCompilationReason = compilationReason;
}

通過reason獲取compilerFilter的寡壮。也就是從這個通過prop定義的值完成設置編譯過濾器。

public static String getCompilerFilterForReason(int reason) {
   return getAndCheckValidity(reason);
}

/ Load the property for the given reason and check for validity. This will throw an
// exception in case the reason or value are invalid.
private static String getAndCheckValidity(int reason) {
   String sysPropValue = SystemProperties.get(getSystemPropertyName(reason));
   if (sysPropValue == null || sysPropValue.isEmpty()
           || !(sysPropValue.equals(DexoptOptions.COMPILER_FILTER_NOOP)
                   || DexFile.isValidCompilerFilter(sysPropValue))) {
       throw new IllegalStateException("Value \"" + sysPropValue +"\" not valid "
               + "(reason " + REASON_STRINGS[reason] + ")");
   } else if (!isFilterAllowedForReason(reason, sysPropValue)) {
       throw new IllegalStateException("Value \"" + sysPropValue +"\" not allowed "
               + "(reason " + REASON_STRINGS[reason] + ")");
   }

   return sysPropValue;
}

PKMS 中定義了14中編譯原因讹弯，對應了每種觸發(fā)dexOpt的原因况既，和執(zhí)行dexOpt定義的編譯過濾器。

// Compilation reasons.
public static final int REASON_FIRST_BOOT = 0;
public static final int REASON_BOOT_AFTER_OTA = 1;
public static final int REASON_POST_BOOT = 2;
public static final int REASON_INSTALL = 3;
public static final int REASON_INSTALL_FAST = 4;
public static final int REASON_INSTALL_BULK = 5;
public static final int REASON_INSTALL_BULK_SECONDARY = 6;
public static final int REASON_INSTALL_BULK_DOWNGRADED = 7;
public static final int REASON_INSTALL_BULK_SECONDARY_DOWNGRADED = 8;
public static final int REASON_BACKGROUND_DEXOPT = 9;
public static final int REASON_AB_OTA = 10;
public static final int REASON_INACTIVE_PACKAGE_DOWNGRADE = 11;
public static final int REASON_CMDLINE = 12;
public static final int REASON_SHARED = 13;

2组民、BackgroundDexOptService

BackgroundDexOptService 是一個JobService棒仍，用于定期執(zhí)行任務。在SystemServer#startOtherService()方法中啟動臭胜，啟動后執(zhí)行兩個任務莫其。

任務一：監(jiān)聽開機廣播，在開機10分鐘-60分鐘內完成post-boot的dex優(yōu)化

任務二：每隔一天執(zhí)行一次idle 場景下dex優(yōu)化耸三。

1695200395519.png

//SystemServer.java 
private void startOtherServices(@NonNull TimingsTraceAndSlog t) {
...
t.traceBegin("StartBackgroundDexOptService");
try {
    BackgroundDexOptService.schedule(context);
} catch (Throwable e) {
    reportWtf("starting StartBackgroundDexOptService", e);
}
t.traceEnd();
...
}

// BackgroundDexOptService.java
public static void schedule(Context context) {
    if (isBackgroundDexoptDisabled()) {//讀屬性"pm.dexopt.disable_bg_dexopt" ,目前是false
        return;
    }
 
    final JobScheduler js = context.getSystemService(JobScheduler.class);
 
    // Schedule a one-off job which scans installed packages and updates
    // out-of-date oat files. Schedule it 10 minutes after the boot complete event,
    // so that we don't overload the boot with additional dex2oat compilations.
    context.registerReceiver(new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            js.schedule(new JobInfo.Builder(JOB_POST_BOOT_UPDATE, sDexoptServiceName)//BackgroundDexOptService 的第一個任務
                    .setMinimumLatency(TimeUnit.MINUTES.toMillis(10)) //最短執(zhí)行時間10min
                    .setOverrideDeadline(TimeUnit.MINUTES.toMillis(60)) //最遲執(zhí)行時間：60mins
                    .build());
            context.unregisterReceiver(this);
            if (DEBUG) {
                Slog.i(TAG, "BootBgDexopt scheduled");
            }
        }
    }, new IntentFilter(Intent.ACTION_BOOT_COMPLETED));//監(jiān)聽開機啟動廣播
 
    // Schedule a daily job which scans installed packages and compiles
    // those with fresh profiling data.
    js.schedule(new JobInfo.Builder(JOB_IDLE_OPTIMIZE, sDexoptServiceName) //BackgroundDexOptService 的第二個任務
                .setRequiresDeviceIdle(true) //設備在idle狀態(tài)
                .setRequiresCharging(true) //充電中
                .setPeriodic(IDLE_OPTIMIZATION_PERIOD) //執(zhí)行周期 一天
                .build());
 
    if (DEBUG) {
        Slog.d(TAG, "BgDexopt scheduled");
    }
}
 
 
//關注第一個job：到點執(zhí)行進入onStartJob方法
public boolean onStartJob(JobParameters params) {
    if (DEBUG) {
        Slog.i(TAG, "onStartJob");
    }
 
    // NOTE: PackageManagerService.isStorageLow uses a different set of criteria from
    // the checks above. This check is not "live" - the value is determined by a background
    // restart with a period of ~1 minute.
    PackageManagerService pm = (PackageManagerService)ServiceManager.getService("package");
    if (pm.isStorageLow()) {//Environment.getDataDirectory().getUsableSpace() < getMemoryLowThreshold(); 為data空間的20%或者低于500MB
        Slog.i(TAG, "Low storage, skipping this run");
        return false;
    }
 
    final ArraySet<String> pkgs = pm.getOptimizablePackages();
    if (pkgs.isEmpty()) {
        Slog.i(TAG, "No packages to optimize");
        return false;
    }
 
    mThermalStatusCutoff =
        SystemProperties.getInt("dalvik.vm.dexopt.thermal-cutoff", THERMAL_CUTOFF_DEFAULT);//2
 
    boolean result;
    if (params.getJobId() == JOB_POST_BOOT_UPDATE) {
        result = runPostBootUpdate(params, pm, pkgs);//進入這里
    } else {
        result = runIdleOptimization(params, pm, pkgs);
    }
 
    return result;
}
 
//執(zhí)行post-boot更新
private boolean runPostBootUpdate(final JobParameters jobParams,
        final PackageManagerService pm, final ArraySet<String> pkgs) {
    if (mExitPostBootUpdate.get()) {
        // This job has already been superseded. Do not start it.
        return false;
    }
    new Thread("BackgroundDexOptService_PostBootUpdate") {//新起一個線程執(zhí)行postBootUpdate
        @Override
        public void run() {
            postBootUpdate(jobParams, pm, pkgs);
        }
 
    }.start();
    return true;
}
 
//子線程運行執(zhí)行所有可優(yōu)化包的dex優(yōu)化
private void postBootUpdate(JobParameters jobParams, PackageManagerService pm,
        ArraySet<String> pkgs) {
    final BatteryManagerInternal batteryManagerInternal =
            LocalServices.getService(BatteryManagerInternal.class);
    final long lowThreshold = getLowStorageThreshold(this);
 
    mAbortPostBootUpdate.set(false);
 
    ArraySet<String> updatedPackages = new ArraySet<>();
    for (String pkg : pkgs) {
        if (mAbortPostBootUpdate.get()) {
            // JobScheduler requested an early abort.
            return;
        }
        if (mExitPostBootUpdate.get()) {
            // Different job, which supersedes this one, is running.
            break;
        }
        if (batteryManagerInternal.getBatteryLevelLow()) {//低電量不執(zhí)行
            // Rather bail than completely drain the battery.
            break;
        }
        long usableSpace = mDataDir.getUsableSpace();
        if (usableSpace < lowThreshold) {//存儲不足
            // Rather bail than completely fill up the disk.
            Slog.w(TAG, "Aborting background dex opt job due to low storage: " +
                    usableSpace);
            break;
        }
        if (DEBUG) {
            Slog.i(TAG, "Updating package " + pkg);
        }
 
        // Update package if needed. Note that there can be no race between concurrent
        // jobs because PackageDexOptimizer.performDexOpt is synchronized.
 
        // checkProfiles is false to avoid merging profiles during boot which
        // might interfere with background compilation (b/28612421).
        // Unfortunately this will also means that "pm.dexopt.boot=speed-profile" will
        // behave differently than "pm.dexopt.bg-dexopt=speed-profile" but that's a
        // trade-off worth doing to save boot time work.
        int result = pm.performDexOptWithStatus(new DexoptOptions(//進入PKMS
                pkg,
                PackageManagerService.REASON_POST_BOOT,//原因
                DexoptOptions.DEXOPT_BOOT_COMPLETE));
        if (result == PackageDexOptimizer.DEX_OPT_PERFORMED)  {
            updatedPackages.add(pkg);
        }
    }
    notifyPinService(updatedPackages);
    notifyPackagesUpdated(updatedPackages);
    // Ran to completion, so we abandon our timeslice and do not reschedule.
    jobFinished(jobParams, /* reschedule */ false);
}
 
進入PKMS 的performDexOptWithStatus方法乱陡。
/* package */ int performDexOptWithStatus(DexoptOptions options) {
    return performDexOptTraced(options);
}
 
 
private int performDexOptTraced(DexoptOptions options) {
    Trace.traceBegin(TRACE_TAG_PACKAGE_MANAGER, "dexopt");
    try {
        return performDexOptInternal(options);
    } finally {
        Trace.traceEnd(TRACE_TAG_PACKAGE_MANAGER);
    }
}
 
 
private int performDexOptInternal(DexoptOptions options) {
    AndroidPackage p;
    PackageSetting pkgSetting;
    synchronized (mLock) {
        p = mPackages.get(options.getPackageName());
        pkgSetting = mSettings.getPackageLPr(options.getPackageName());
        if (p == null || pkgSetting == null) {
            // Package could not be found. Report failure.
            return PackageDexOptimizer.DEX_OPT_FAILED;
        }
        mPackageUsage.maybeWriteAsync(mSettings.getPackagesLocked());
        mCompilerStats.maybeWriteAsync();
    }
    final long callingId = Binder.clearCallingIdentity();
    try {
        synchronized (mInstallLock) {
            return performDexOptInternalWithDependenciesLI(p, pkgSetting, options); //進入這里
        }
    } finally {
        Binder.restoreCallingIdentity(callingId);
    }
}
 
 
private int performDexOptInternalWithDependenciesLI(AndroidPackage p,
        @NonNull PackageSetting pkgSetting, DexoptOptions options) {
    // System server gets a special path.
    if (PLATFORM_PACKAGE_NAME.equals(p.getPackageName())) {
        return mDexManager.dexoptSystemServer(options);//android 走系統(tǒng)
    }
 
    // Select the dex optimizer based on the force parameter.
    // Note: The force option is rarely used (cmdline input for testing, mostly), so it's OK to
    //       allocate an object here.
    PackageDexOptimizer pdo = options.isForce()
            ? new PackageDexOptimizer.ForcedUpdatePackageDexOptimizer(mPackageDexOptimizer)
            : mPackageDexOptimizer; //如果有攜帶f就要強制編譯，無其他邏輯
 
    // Dexopt all dependencies first. Note: we ignore the return value and march on
    // on errors.
    // Note that we are going to call performDexOpt on those libraries as many times as
    // they are referenced in packages. When we do a batch of performDexOpt (for example
    // at boot, or background job), the passed 'targetCompilerFilter' stays the same,
    // and the first package that uses the library will dexopt it. The
    // others will see that the compiled code for the library is up to date.
    Collection<SharedLibraryInfo> deps = findSharedLibraries(pkgSetting);
    final String[] instructionSets = getAppDexInstructionSets(
            AndroidPackageUtils.getPrimaryCpuAbi(p, pkgSetting),
            AndroidPackageUtils.getSecondaryCpuAbi(p, pkgSetting));
    if (!deps.isEmpty()) {
        DexoptOptions libraryOptions = new DexoptOptions(options.getPackageName(),
                options.getCompilationReason(), options.getCompilerFilter(),
                options.getSplitName(),
                options.getFlags() | DexoptOptions.DEXOPT_AS_SHARED_LIBRARY);
        for (SharedLibraryInfo info : deps) {
            AndroidPackage depPackage = null;
            PackageSetting depPackageSetting = null;
            synchronized (mLock) {
                depPackage = mPackages.get(info.getPackageName());
                depPackageSetting = mSettings.getPackageLPr(info.getPackageName());
            }
            if (depPackage != null && depPackageSetting != null) {
                // TODO: Analyze and investigate if we (should) profile libraries.
                pdo.performDexOpt(depPackage, depPackageSetting, instructionSets, //先對依賴庫進行dex優(yōu)化
                        getOrCreateCompilerPackageStats(depPackage),
                        mDexManager.getPackageUseInfoOrDefault(depPackage.getPackageName()),
                        libraryOptions);
            } else {
                // TODO(ngeoffray): Support dexopting system shared libraries.
            }
        }
    }
 
    return pdo.performDexOpt(p, pkgSetting, instructionSets,//進入PackageDexOptimizer#performDexOpt流程吕晌，上面已經分析過蛋褥。
            getOrCreateCompilerPackageStats(p),
            mDexManager.getPackageUseInfoOrDefault(p.getPackageName()), options);
}