[worker] Revert Xcode build tool prewarming

packages/build-tools/resources/xcode-local-cache-plugin/eas_local_cas_plugin.c

@@ -0,0 +1,296 @@
+#include <dlfcn.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+/*
+ * Xcode loads one plugin that implements the llcas_* API. This small shim loads
+ * Apple's local CAS plugin and forwards every API call to it. The only exception
+ * is the "remote-service-path" option: Xcode needs that option to schedule C and
+ * Objective-C cache tasks, but Apple's local plugin does not need a remote service.
+ * The shim accepts and discards that option. No cache data leaves the machine.
+ */
+
+typedef void *llcas_cas_options_t;
+typedef void *llcas_cas_t;
+typedef void *llcas_cancellable_t;
+typedef uint32_t llcas_lookup_result_t;
+
+typedef struct {
+  const uint8_t *data;
+  size_t size;
+} llcas_digest_t;
+
+typedef struct {
+  const void *data;
+  size_t size;
+} llcas_data_t;
+
+typedef struct {
+  uint64_t opaque;
+} llcas_objectid_t;
+
+typedef struct {
+  uint64_t opaque;
+} llcas_loaded_object_t;
+
+typedef struct {
+  uint64_t opaque_b;
+  uint64_t opaque_e;
+} llcas_object_refs_t;
+
+typedef void (*llcas_cas_load_object_cb)(void *, llcas_lookup_result_t,
+                                         llcas_loaded_object_t, char *);
+typedef void (*llcas_actioncache_get_cb)(void *, llcas_lookup_result_t,
+                                         llcas_objectid_t, char *);
+typedef void (*llcas_actioncache_put_cb)(void *, bool, char *);
+
+static void *apple_plugin_handle;
+
+static void *apple_plugin_symbol(const char *name) {
+  if (apple_plugin_handle == NULL) {
+    const char *path = getenv("EAS_XCODE_LOCAL_CAS_APPLE_PLUGIN");
+    if (path == NULL || path[0] == '\0') {
+      path = "/Applications/Xcode.app/Contents/Developer/usr/lib/"
+             "libToolchainCASPlugin.dylib";
+    }
+    apple_plugin_handle = dlopen(path, RTLD_NOW | RTLD_LOCAL);
+    if (apple_plugin_handle == NULL) {
+      fprintf(stderr, "EAS local CAS plugin could not load %s: %s\n", path,
+              dlerror());
+      abort();
+    }
+  }
+
+  void *symbol = dlsym(apple_plugin_handle, name);
+  if (symbol == NULL) {
+    fprintf(stderr, "EAS local CAS plugin could not find %s: %s\n", name,
+            dlerror());
+    abort();
+  }
+  return symbol;
+}
+
+#define APPLE_PLUGIN(name, type) ((type)apple_plugin_symbol(#name))
+
+void llcas_get_plugin_version(uint32_t *major, uint32_t *minor) {
+  typedef void (*fn_t)(uint32_t *, uint32_t *);
+  APPLE_PLUGIN(llcas_get_plugin_version, fn_t)(major, minor);
+}
+
+void llcas_string_dispose(char *value) {
+  typedef void (*fn_t)(char *);
+  APPLE_PLUGIN(llcas_string_dispose, fn_t)(value);
+}
+
+void llcas_cancellable_cancel(llcas_cancellable_t token) {
+  typedef void (*fn_t)(llcas_cancellable_t);
+  APPLE_PLUGIN(llcas_cancellable_cancel, fn_t)(token);
+}
+
+void llcas_cancellable_dispose(llcas_cancellable_t token) {
+  typedef void (*fn_t)(llcas_cancellable_t);
+  APPLE_PLUGIN(llcas_cancellable_dispose, fn_t)(token);
+}
+
+llcas_cas_options_t llcas_cas_options_create(void) {
+  typedef llcas_cas_options_t (*fn_t)(void);
+  return APPLE_PLUGIN(llcas_cas_options_create, fn_t)();
+}
+
+void llcas_cas_options_dispose(llcas_cas_options_t options) {
+  typedef void (*fn_t)(llcas_cas_options_t);
+  APPLE_PLUGIN(llcas_cas_options_dispose, fn_t)(options);
+}
+
+void llcas_cas_options_set_client_version(llcas_cas_options_t options,
+                                          uint32_t major, uint32_t minor) {
+  typedef void (*fn_t)(llcas_cas_options_t, uint32_t, uint32_t);
+  APPLE_PLUGIN(llcas_cas_options_set_client_version, fn_t)(options, major, minor);
+}
+
+void llcas_cas_options_set_ondisk_path(llcas_cas_options_t options,
+                                       const char *path) {
+  typedef void (*fn_t)(llcas_cas_options_t, const char *);
+  APPLE_PLUGIN(llcas_cas_options_set_ondisk_path, fn_t)(options, path);
+}
+
+bool llcas_cas_options_set_option(llcas_cas_options_t options, const char *name,
+                                  const char *value, char **error) {
+  if (name != NULL && strcmp(name, "remote-service-path") == 0) {
+    if (error != NULL) {
+      *error = NULL;
+    }
+    return false;
+  }
+  typedef bool (*fn_t)(llcas_cas_options_t, const char *, const char *,
+                       char **);
+  return APPLE_PLUGIN(llcas_cas_options_set_option, fn_t)(options, name, value,
+                                                          error);
+}
+
+llcas_cas_t llcas_cas_create(llcas_cas_options_t options, char **error) {
+  typedef llcas_cas_t (*fn_t)(llcas_cas_options_t, char **);
+  return APPLE_PLUGIN(llcas_cas_create, fn_t)(options, error);
+}
+
+void llcas_cas_dispose(llcas_cas_t cas) {
+  typedef void (*fn_t)(llcas_cas_t);
+  APPLE_PLUGIN(llcas_cas_dispose, fn_t)(cas);
+}
+
+int64_t llcas_cas_get_ondisk_size(llcas_cas_t cas, char **error) {
+  typedef int64_t (*fn_t)(llcas_cas_t, char **);
+  return APPLE_PLUGIN(llcas_cas_get_ondisk_size, fn_t)(cas, error);
+}
+
+bool llcas_cas_set_ondisk_size_limit(llcas_cas_t cas, int64_t size,
+                                     char **error) {
+  typedef bool (*fn_t)(llcas_cas_t, int64_t, char **);
+  return APPLE_PLUGIN(llcas_cas_set_ondisk_size_limit, fn_t)(cas, size, error);
+}
+
+bool llcas_cas_prune_ondisk_data(llcas_cas_t cas, char **error) {
+  typedef bool (*fn_t)(llcas_cas_t, char **);
+  return APPLE_PLUGIN(llcas_cas_prune_ondisk_data, fn_t)(cas, error);
+}
+
+char *llcas_cas_get_hash_schema_name(llcas_cas_t cas) {
+  typedef char *(*fn_t)(llcas_cas_t);
+  return APPLE_PLUGIN(llcas_cas_get_hash_schema_name, fn_t)(cas);
+}
+
+uint32_t llcas_digest_parse(llcas_cas_t cas, const char *printed,
+                            uint8_t *bytes, size_t bytes_size, char **error) {
+  typedef uint32_t (*fn_t)(llcas_cas_t, const char *, uint8_t *, size_t,
+                           char **);
+  return APPLE_PLUGIN(llcas_digest_parse, fn_t)(cas, printed, bytes,
+                                                bytes_size, error);
+}
+
+bool llcas_digest_print(llcas_cas_t cas, llcas_digest_t digest, char **printed,
+                        char **error) {
+  typedef bool (*fn_t)(llcas_cas_t, llcas_digest_t, char **, char **);
+  return APPLE_PLUGIN(llcas_digest_print, fn_t)(cas, digest, printed, error);
+}
+
+bool llcas_cas_get_objectid(llcas_cas_t cas, llcas_digest_t digest,
+                            llcas_objectid_t *object, char **error) {
+  typedef bool (*fn_t)(llcas_cas_t, llcas_digest_t, llcas_objectid_t *,
+                       char **);
+  return APPLE_PLUGIN(llcas_cas_get_objectid, fn_t)(cas, digest, object, error);
+}
+
+llcas_digest_t llcas_objectid_get_digest(llcas_cas_t cas,
+                                         llcas_objectid_t object) {
+  typedef llcas_digest_t (*fn_t)(llcas_cas_t, llcas_objectid_t);
+  return APPLE_PLUGIN(llcas_objectid_get_digest, fn_t)(cas, object);
+}
+
+llcas_lookup_result_t llcas_cas_contains_object(llcas_cas_t cas,
+                                                llcas_objectid_t object,
+                                                bool globally, char **error) {
+  typedef llcas_lookup_result_t (*fn_t)(llcas_cas_t, llcas_objectid_t, bool,
+                                        char **);
+  return APPLE_PLUGIN(llcas_cas_contains_object, fn_t)(cas, object, globally,
+                                                       error);
+}
+
+llcas_lookup_result_t llcas_cas_load_object(llcas_cas_t cas,
+                                            llcas_objectid_t object,
+                                            llcas_loaded_object_t *loaded,
+                                            char **error) {
+  typedef llcas_lookup_result_t (*fn_t)(llcas_cas_t, llcas_objectid_t,
+                                        llcas_loaded_object_t *, char **);
+  return APPLE_PLUGIN(llcas_cas_load_object, fn_t)(cas, object, loaded, error);
+}
+
+void llcas_cas_load_object_async(llcas_cas_t cas, llcas_objectid_t object,
+                                 void *context,
+                                 llcas_cas_load_object_cb callback,
+                                 llcas_cancellable_t *cancellable) {
+  typedef void (*fn_t)(llcas_cas_t, llcas_objectid_t, void *,
+                       llcas_cas_load_object_cb, llcas_cancellable_t *);
+  APPLE_PLUGIN(llcas_cas_load_object_async,
+               fn_t)(cas, object, context, callback, cancellable);
+}
+
+bool llcas_cas_store_object(llcas_cas_t cas, llcas_data_t data,
+                            const llcas_objectid_t *refs, size_t refs_count,
+                            llcas_objectid_t *stored, char **error) {
+  typedef bool (*fn_t)(llcas_cas_t, llcas_data_t, const llcas_objectid_t *,
+                       size_t, llcas_objectid_t *, char **);
+  return APPLE_PLUGIN(llcas_cas_store_object,
+                      fn_t)(cas, data, refs, refs_count, stored, error);
+}
+
+llcas_data_t llcas_loaded_object_get_data(llcas_cas_t cas,
+                                          llcas_loaded_object_t object) {
+  typedef llcas_data_t (*fn_t)(llcas_cas_t, llcas_loaded_object_t);
+  return APPLE_PLUGIN(llcas_loaded_object_get_data, fn_t)(cas, object);
+}
+
+llcas_object_refs_t llcas_loaded_object_get_refs(llcas_cas_t cas,
+                                                 llcas_loaded_object_t object) {
+  typedef llcas_object_refs_t (*fn_t)(llcas_cas_t, llcas_loaded_object_t);
+  return APPLE_PLUGIN(llcas_loaded_object_get_refs, fn_t)(cas, object);
+}
+
+size_t llcas_object_refs_get_count(llcas_cas_t cas, llcas_object_refs_t refs) {
+  typedef size_t (*fn_t)(llcas_cas_t, llcas_object_refs_t);
+  return APPLE_PLUGIN(llcas_object_refs_get_count, fn_t)(cas, refs);
+}
+
+llcas_objectid_t llcas_object_refs_get_id(llcas_cas_t cas,
+                                          llcas_object_refs_t refs,
+                                          size_t index) {
+  typedef llcas_objectid_t (*fn_t)(llcas_cas_t, llcas_object_refs_t, size_t);
+  return APPLE_PLUGIN(llcas_object_refs_get_id, fn_t)(cas, refs, index);
+}
+
+llcas_lookup_result_t llcas_actioncache_get_for_digest(llcas_cas_t cas,
+                                                       llcas_digest_t digest,
+                                                       llcas_objectid_t *result,
+                                                       bool globally,
+                                                       char **error) {
+  typedef llcas_lookup_result_t (*fn_t)(llcas_cas_t, llcas_digest_t,
+                                        llcas_objectid_t *, bool, char **);
+  return APPLE_PLUGIN(llcas_actioncache_get_for_digest,
+                      fn_t)(cas, digest, result, globally, error);
+}
+
+void llcas_actioncache_get_for_digest_async(llcas_cas_t cas,
+                                            llcas_digest_t digest,
+                                            bool globally, void *context,
+                                            llcas_actioncache_get_cb callback,
+                                            llcas_cancellable_t *cancellable) {
+  typedef void (*fn_t)(llcas_cas_t, llcas_digest_t, bool, void *,
+                       llcas_actioncache_get_cb, llcas_cancellable_t *);
+  APPLE_PLUGIN(llcas_actioncache_get_for_digest_async,
+               fn_t)(cas, digest, globally, context, callback, cancellable);
+}
+
+bool llcas_actioncache_put_for_digest(llcas_cas_t cas, llcas_digest_t digest,
+                                      llcas_objectid_t value, bool globally,
+                                      char **error) {
+  typedef bool (*fn_t)(llcas_cas_t, llcas_digest_t, llcas_objectid_t, bool,
+                       char **);
+  return APPLE_PLUGIN(llcas_actioncache_put_for_digest,
+                      fn_t)(cas, digest, value, globally, error);
+}
+
+void llcas_actioncache_put_for_digest_async(llcas_cas_t cas,
+                                            llcas_digest_t digest,
+                                            llcas_objectid_t value,
+                                            bool globally, void *context,
+                                            llcas_actioncache_put_cb callback,
+                                            llcas_cancellable_t *cancellable) {
+  typedef void (*fn_t)(llcas_cas_t, llcas_digest_t, llcas_objectid_t, bool,
+                       void *, llcas_actioncache_put_cb, llcas_cancellable_t *);
+  APPLE_PLUGIN(llcas_actioncache_put_for_digest_async,
+               fn_t)(cas, digest, value, globally, context, callback,
+                     cancellable);
+}

packages/build-tools/src/builders/ios.ts

@@ -18,8 +18,12 @@ import { downloadApplicationArchiveAsync } from '../ios/resign';
 import { resolveArtifactPath, resolveBuildConfiguration, resolveScheme } from '../ios/resolve';
 import { Sentry } from '../sentry';
 import { parseAndReportXcactivitylog } from '../steps/utils/ios/xcactivitylog';
-import { cacheStatsAsync, restoreCcacheAsync } from '../steps/functions/restoreBuildCache';
-import { saveCcacheAsync } from '../steps/functions/saveBuildCache';
+import {
+  cacheStatsAsync,
+  restoreCcacheAsync,
+  restoreXcodeCompilationCacheAsync,
+} from '../steps/functions/restoreBuildCache';
+import { saveCcacheAsync, saveXcodeCompilationCacheAsync } from '../steps/functions/saveBuildCache';
 import { uploadApplicationArchive } from '../utils/artifacts';
 import {
   configureExpoUpdatesIfInstalledAsync,
@@ -100,13 +104,21 @@ async function buildInnerAsync(
         return;
       }
       await ctx.cacheManager?.restoreCache(ctx);
-      await restoreCcacheAsync({
-        logger: ctx.logger,
-        workingDirectory,
-        platform: ctx.job.platform,
-        env: ctx.env,
-        secrets: ctx.job.secrets,
-      });
+      await Promise.all([
+        restoreCcacheAsync({
+          logger: ctx.logger,
+          workingDirectory,
+          platform: ctx.job.platform,
+          env: ctx.env,
+          secrets: ctx.job.secrets,
+        }),
+        restoreXcodeCompilationCacheAsync({
+          logger: ctx.logger,
+          workingDirectory,
+          env: ctx.env,
+          secrets: ctx.job.secrets,
+        }),
+      ]);
     });
 
     await ctx.runBuildPhase(BuildPhase.INSTALL_PODS, async () => {
@@ -242,14 +254,22 @@ async function buildInnerAsync(
       return;
     }
     await ctx.cacheManager?.saveCache(ctx);
-    await saveCcacheAsync({
-      logger: ctx.logger,
-      workingDirectory,
-      platform: ctx.job.platform,
-      evictUsedBefore,
-      env: ctx.env,
-      secrets: ctx.job.secrets,
-    });
+    await Promise.all([
+      saveCcacheAsync({
+        logger: ctx.logger,
+        workingDirectory,
+        platform: ctx.job.platform,
+        evictUsedBefore,
+        env: ctx.env,
+        secrets: ctx.job.secrets,
+      }),
+      saveXcodeCompilationCacheAsync({
+        logger: ctx.logger,
+        workingDirectory,
+        env: ctx.env,
+        secrets: ctx.job.secrets,
+      }),
+    ]);
   });
 
   await ctx.runBuildPhase(BuildPhase.CACHE_STATS, async () => {

packages/build-tools/src/ios/__tests__/compilationCache.test.ts

@@ -0,0 +1,161 @@
+import spawn from '@expo/turtle-spawn';
+import { vol } from 'memfs';
+import os from 'os';
+import path from 'path';
+
+import { createMockLogger } from '../../__tests__/utils/logger';
+import {
+  XCODE_COMPILATION_CACHE_ENV,
+  XCODE_COMPILATION_CACHE_RELATIVE_PATH,
+  compressXcodeCompilationCacheAsync,
+  decompressXcodeCompilationCacheAsync,
+  prepareXcodeCompilationCacheEnvAsync,
+} from '../compilationCache';
+
+jest.mock('@expo/turtle-spawn', () => ({
+  __esModule: true,
+  default: jest.fn(),
+}));
+
+const DEVELOPER_DIRECTORY = '/Applications/Xcode.app/Contents/Developer';
+const APPLE_PLUGIN_PATH = path.join(DEVELOPER_DIRECTORY, 'usr/lib/libToolchainCASPlugin.dylib');
+const BUNDLED_SHIM_PATH = path.resolve(
+  __dirname,
+  '../../../bin/libeas_xcode_local_cas_plugin.dylib'
+);
+
+describe(prepareXcodeCompilationCacheEnvAsync, () => {
+  test('does nothing without the explicit opt-in', async () => {
+    const result = await prepareXcodeCompilationCacheEnvAsync({
+      derivedDataPath: '/project/ios/build',
+      env: {},
+      logger: createMockLogger(),
+    });
+
+    expect(result).toEqual({});
+    expect(spawn).not.toHaveBeenCalled();
+  });
+
+  test('enables compilation caching after validating the bundled arm64 shim', async () => {
+    vol.fromJSON({
+      [BUNDLED_SHIM_PATH]: 'bundled shim',
+      [APPLE_PLUGIN_PATH]: 'Apple plugin',
+    });
+    vol.mkdirSync(os.tmpdir(), { recursive: true });
+    jest.mocked(spawn).mockResolvedValue({} as any);
+
+    const result = await prepareXcodeCompilationCacheEnvAsync({
+      derivedDataPath: '/project/ios/build',
+      env: {
+        [XCODE_COMPILATION_CACHE_ENV]: '1',
+        DEVELOPER_DIR: DEVELOPER_DIRECTORY,
+      },
+      logger: createMockLogger(),
+    });
+
+    expect(spawn).toHaveBeenCalledWith(
+      'xcrun',
+      expect.arrayContaining([
+        'llvm-cas',
+        `--fcas-plugin-path=${BUNDLED_SHIM_PATH}`,
+        '--fcas-plugin-option=remote-service-path=/dev/null',
+        '--ingest',
+        BUNDLED_SHIM_PATH,
+      ]),
+      expect.objectContaining({
+        env: expect.objectContaining({
+          EAS_XCODE_LOCAL_CAS_APPLE_PLUGIN: APPLE_PLUGIN_PATH,
+        }),
+      })
+    );
+    expect(result).toEqual({
+      EAS_XCODE_LOCAL_CAS_APPLE_PLUGIN: APPLE_PLUGIN_PATH,
+      GYM_XCARGS: `COMPILATION_CACHE_ENABLE_CACHING=YES COMPILATION_CACHE_ENABLE_DIAGNOSTIC_REMARKS=YES COMPILATION_CACHE_ENABLE_PLUGIN=YES COMPILATION_CACHE_PLUGIN_PATH=${BUNDLED_SHIM_PATH} COMPILATION_CACHE_REMOTE_SERVICE_PATH=/dev/null`,
+      GYM_DERIVED_DATA_PATH: '/project/ios/build',
+    });
+  });
+
+  test('does not enable compilation caching when the bundled shim is missing', async () => {
+    const logger = createMockLogger();
+    vol.fromJSON({
+      [APPLE_PLUGIN_PATH]: 'Apple plugin',
+    });
+
+    const result = await prepareXcodeCompilationCacheEnvAsync({
+      derivedDataPath: '/project/ios/build',
+      env: {
+        [XCODE_COMPILATION_CACHE_ENV]: '1',
+        DEVELOPER_DIR: DEVELOPER_DIRECTORY,
+      },
+      logger,
+    });
+
+    expect(spawn).not.toHaveBeenCalled();
+    expect(result).toEqual({});
+    expect(logger.warn).toHaveBeenCalledWith(
+      expect.objectContaining({ err: expect.any(Error) }),
+      expect.stringContaining('compilation caching is disabled')
+    );
+  });
+
+  test('does not enable compilation caching when the bundled shim is incompatible', async () => {
+    const logger = createMockLogger();
+    vol.fromJSON({
+      [BUNDLED_SHIM_PATH]: 'bundled shim',
+      [APPLE_PLUGIN_PATH]: 'Apple plugin',
+    });
+    vol.mkdirSync(os.tmpdir(), { recursive: true });
+    jest.mocked(spawn).mockRejectedValue(new Error('incompatible plugin'));
+
+    const result = await prepareXcodeCompilationCacheEnvAsync({
+      derivedDataPath: '/project/ios/build',
+      env: {
+        [XCODE_COMPILATION_CACHE_ENV]: '1',
+        DEVELOPER_DIR: DEVELOPER_DIRECTORY,
+      },
+      logger,
+    });
+
+    expect(result).toEqual({});
+    expect(logger.warn).toHaveBeenCalledWith(
+      expect.objectContaining({ err: expect.any(Error) }),
+      expect.stringContaining('compilation caching is disabled')
+    );
+  });
+});
+
+describe('Xcode compilation cache archives', () => {
+  test('uses system tar to preserve sparse files', async () => {
+    const workingDirectory = '/working-directory';
+    vol.fromJSON({
+      [path.join(workingDirectory, XCODE_COMPILATION_CACHE_RELATIVE_PATH, 'cache.db')]: 'cache',
+    });
+    vol.mkdirSync(os.tmpdir(), { recursive: true });
+    jest.mocked(spawn).mockResolvedValue({} as any);
+
+    const { archivePath } = await compressXcodeCompilationCacheAsync({
+      workingDirectory,
+      env: {},
+      logger: createMockLogger(),
+    });
+
+    expect(spawn).toHaveBeenCalledWith(
+      'tar',
+      ['-czf', archivePath, '-C', workingDirectory, XCODE_COMPILATION_CACHE_RELATIVE_PATH],
+      expect.any(Object)
+    );
+
+    await decompressXcodeCompilationCacheAsync({
+      archivePath,
+      workingDirectory,
+      env: {},
+      logger: createMockLogger(),
+    });
+
+    expect(spawn).toHaveBeenCalledWith(
+      'tar',
+      ['-xzSf', archivePath, '-C', workingDirectory],
+      expect.any(Object)
+    );
+  });
+});

packages/build-tools/src/ios/__tests__/fastlane.test.ts

@@ -6,6 +6,7 @@ import path from 'path';
 import { createTestIosJob } from '../../__tests__/utils/job';
 import { createMockLogger } from '../../__tests__/utils/logger';
 import { BuildContext } from '../../context';
+import * as CompilationCache from '../compilationCache';
 import { Credentials } from '../credentials/manager';
 import { DistributionType } from '../credentials/provisioningProfile';
 import { runFastlaneGym } from '../fastlane';
@@ -23,13 +24,19 @@ const WORKING_DIR = '/workingdir';
 // BuildContext.getReactNativeProjectDirectory() nests the RN project under `${workingdir}/build`.
 const IOS_DIR = path.join(WORKING_DIR, 'build', 'ios');
 
-function makeIosBuildContext({ simulator }: { simulator: boolean }): BuildContext<Ios.Job> {
+function makeIosBuildContext({
+  simulator,
+  env = {},
+}: {
+  simulator: boolean;
+  env?: Record<string, string>;
+}): BuildContext<Ios.Job> {
   const job: Ios.Job = { ...createTestIosJob(), simulator };
   return new BuildContext(job, {
     workingdir: WORKING_DIR,
     logger: createMockLogger(),
     logBuffer: { getLogs: () => [], getPhaseLogs: () => [] },
-    env: { __API_SERVER_URL: 'http://api.expo.test' },
+    env: { __API_SERVER_URL: 'http://api.expo.test', ...env },
     uploadArtifact: jest.fn(),
   });
 }
@@ -71,6 +78,10 @@ describe(runFastlaneGym, () => {
     (spawn as jest.Mock).mockClear();
   });
 
+  afterEach(() => {
+    jest.restoreAllMocks();
+  });
+
   describe.each([
     {
       name: 'archive',
@@ -125,4 +136,68 @@ describe(runFastlaneGym, () => {
       workspacePath: IOS_DIR,
     });
   });
+
+  it('enables local Swift, C, and Objective-C compilation caching', async () => {
+    jest.spyOn(CompilationCache, 'prepareXcodeCompilationCacheEnvAsync').mockResolvedValue({
+      GYM_XCARGS:
+        'OTHER_SWIFT_FLAGS=-warnings-as-errors COMPILATION_CACHE_ENABLE_CACHING=YES COMPILATION_CACHE_ENABLE_DIAGNOSTIC_REMARKS=YES COMPILATION_CACHE_ENABLE_PLUGIN=YES COMPILATION_CACHE_PLUGIN_PATH=/workingdir/bin/libeas_xcode_local_cas_plugin.dylib COMPILATION_CACHE_REMOTE_SERVICE_PATH=/dev/null',
+      EAS_XCODE_LOCAL_CAS_APPLE_PLUGIN:
+        '/Applications/Xcode.app/Contents/Developer/usr/lib/libToolchainCASPlugin.dylib',
+      GYM_DERIVED_DATA_PATH: path.join(IOS_DIR, 'build'),
+    });
+    const ctx = makeIosBuildContext({
+      simulator: false,
+      env: {
+        EAS_BUILD_XCODE_COMPILATION_CACHE: '1',
+        GYM_XCARGS: 'OTHER_SWIFT_FLAGS=-warnings-as-errors',
+      },
+    });
+
+    await runFastlaneGym(ctx, {
+      scheme: 'App',
+      credentials: ARCHIVE_CREDENTIALS,
+      entitlements: null,
+    });
+
+    expect(spawn).toHaveBeenCalledWith(
+      'fastlane',
+      ['gym'],
+      expect.objectContaining({
+        env: expect.objectContaining({
+          GYM_XCARGS:
+            'OTHER_SWIFT_FLAGS=-warnings-as-errors COMPILATION_CACHE_ENABLE_CACHING=YES COMPILATION_CACHE_ENABLE_DIAGNOSTIC_REMARKS=YES COMPILATION_CACHE_ENABLE_PLUGIN=YES COMPILATION_CACHE_PLUGIN_PATH=/workingdir/bin/libeas_xcode_local_cas_plugin.dylib COMPILATION_CACHE_REMOTE_SERVICE_PATH=/dev/null',
+          EAS_XCODE_LOCAL_CAS_APPLE_PLUGIN:
+            '/Applications/Xcode.app/Contents/Developer/usr/lib/libToolchainCASPlugin.dylib',
+          GYM_DERIVED_DATA_PATH: path.join(IOS_DIR, 'build'),
+        }),
+      })
+    );
+  });
+
+  it('does not enable compilation caching when the local plugin cannot be prepared', async () => {
+    const ctx = makeIosBuildContext({
+      simulator: false,
+      env: {
+        EAS_BUILD_XCODE_COMPILATION_CACHE: '1',
+      },
+    });
+
+    await runFastlaneGym(ctx, {
+      scheme: 'App',
+      credentials: ARCHIVE_CREDENTIALS,
+      entitlements: null,
+    });
+
+    expect(spawn).toHaveBeenCalledWith(
+      'fastlane',
+      ['gym'],
+      expect.objectContaining({
+        env: expect.not.objectContaining({ GYM_XCARGS: expect.any(String) }),
+      })
+    );
+    expect(ctx.logger.warn).toHaveBeenCalledWith(
+      expect.objectContaining({ err: expect.any(Error) }),
+      expect.stringContaining('compilation caching is disabled')
+    );
+  });
 });

packages/build-tools/src/ios/compilationCache.ts

@@ -0,0 +1,194 @@
+import { Env, Platform } from '@expo/eas-build-job';
+import { bunyan } from '@expo/logger';
+import spawn from '@expo/turtle-spawn';
+import { createHash } from 'crypto';
+import fs from 'fs-extra';
+import os from 'os';
+import path from 'path';
+
+import { CACHE_KEY_PREFIX_BY_PLATFORM, generateDefaultBuildCacheKeyAsync } from '../utils/cacheKey';
+
+export const XCODE_COMPILATION_CACHE_ENV = 'EAS_BUILD_XCODE_COMPILATION_CACHE';
+export const XCODE_COMPILATION_CACHE_RELATIVE_PATH = 'ios/build/CompilationCache.noindex';
+
+export function getXcodeCompilationCachePath(derivedDataPath: string): string {
+  return path.join(derivedDataPath, 'CompilationCache.noindex');
+}
+
+async function prepareXcodeLocalCompilationCachePluginAsync({
+  env,
+  logger,
+}: {
+  env: Env;
+  logger: bunyan;
+}): Promise<{ pluginPath: string; applePluginPath: string }> {
+  const bundledPluginPath = path.resolve(
+    __dirname,
+    '../../bin/libeas_xcode_local_cas_plugin.dylib'
+  );
+  const developerDirectory =
+    env.DEVELOPER_DIR ??
+    (
+      await spawn('xcode-select', ['--print-path'], {
+        env,
+        logger,
+      })
+    ).stdout.trim();
+  const applePluginPath = path.join(
+    developerDirectory,
+    'usr',
+    'lib',
+    'libToolchainCASPlugin.dylib'
+  );
+
+  if (!(await fs.pathExists(applePluginPath))) {
+    throw new Error(`The Xcode CAS plugin is missing at ${applePluginPath}.`);
+  }
+  if (!(await fs.pathExists(bundledPluginPath))) {
+    throw new Error(`The EAS local CAS plugin is missing at ${bundledPluginPath}.`);
+  }
+
+  const validationDirectory = await fs.mkdtemp(
+    path.join(os.tmpdir(), 'eas-xcode-local-cache-validation-')
+  );
+  try {
+    await spawn(
+      'xcrun',
+      [
+        'llvm-cas',
+        `--fcas-plugin-path=${bundledPluginPath}`,
+        '--fcas-plugin-option=remote-service-path=/dev/null',
+        `--cas=${path.join(validationDirectory, 'cas')}`,
+        '--ingest',
+        bundledPluginPath,
+      ],
+      {
+        env: { ...env, EAS_XCODE_LOCAL_CAS_APPLE_PLUGIN: applePluginPath },
+        logger,
+      }
+    );
+  } finally {
+    await fs.remove(validationDirectory);
+  }
+
+  return { pluginPath: bundledPluginPath, applePluginPath };
+}
+
+export async function compressXcodeCompilationCacheAsync({
+  workingDirectory,
+  env,
+  logger,
+}: {
+  workingDirectory: string;
+  env: Env;
+  logger: bunyan;
+}): Promise<{ archivePath: string }> {
+  const cachePath = path.join(workingDirectory, XCODE_COMPILATION_CACHE_RELATIVE_PATH);
+  if (!(await fs.pathExists(cachePath))) {
+    throw new Error(`The Xcode compilation cache does not exist at ${cachePath}.`);
+  }
+
+  const archiveDirectory = await fs.mkdtemp(path.join(os.tmpdir(), 'xcode-compilation-cache-'));
+  const archivePath = path.join(archiveDirectory, 'cache.tar.gz');
+  await spawn(
+    'tar',
+    ['-czf', archivePath, '-C', workingDirectory, XCODE_COMPILATION_CACHE_RELATIVE_PATH],
+    { env, logger }
+  );
+  return { archivePath };
+}
+
+export async function decompressXcodeCompilationCacheAsync({
+  archivePath,
+  workingDirectory,
+  env,
+  logger,
+}: {
+  archivePath: string;
+  workingDirectory: string;
+  env: Env;
+  logger: bunyan;
+}): Promise<void> {
+  await fs.ensureDir(workingDirectory);
+  await spawn('tar', ['-xzSf', archivePath, '-C', workingDirectory], { env, logger });
+}
+
+export async function generateXcodeCompilationCacheKeyAsync({
+  workingDirectory,
+  env,
+  logger,
+}: {
+  workingDirectory: string;
+  env: Env;
+  logger: bunyan;
+}): Promise<{ key: string; keyPrefix: string; xcodeVersion: string }> {
+  const xcodeVersion = (
+    await spawn('xcodebuild', ['-version'], {
+      env,
+      logger,
+    })
+  ).stdout.trim();
+  const xcodeVersionHash = createHash('sha256').update(xcodeVersion).digest('hex').slice(0, 16);
+  const ccacheKey = await generateDefaultBuildCacheKeyAsync(workingDirectory, Platform.IOS);
+  const dependencyHash = ccacheKey.slice(CACHE_KEY_PREFIX_BY_PLATFORM[Platform.IOS].length);
+  const keyPrefix = `ios-xcode-compilation-cache-${xcodeVersionHash}-`;
+
+  return {
+    key: `${keyPrefix}${dependencyHash}`,
+    keyPrefix,
+    xcodeVersion: xcodeVersion.replace(/\s+/g, ' '),
+  };
+}
+
+export async function prepareXcodeCompilationCacheEnvAsync({
+  derivedDataPath,
+  env,
+  logger,
+}: {
+  derivedDataPath: string;
+  env: Env;
+  logger: bunyan;
+}): Promise<Env> {
+  if (env[XCODE_COMPILATION_CACHE_ENV] !== '1') {
+    return {};
+  }
+
+  let plugin: { pluginPath: string; applePluginPath: string };
+  try {
+    plugin = await prepareXcodeLocalCompilationCachePluginAsync({
+      env,
+      logger,
+    });
+    logger.info(`The EAS local Xcode CAS plugin is ready at ${plugin.pluginPath}.`);
+  } catch (error: any) {
+    logger.warn(
+      { err: error },
+      'The EAS local Xcode CAS plugin is missing or incompatible. Xcode compilation caching is disabled.'
+    );
+    return {};
+  }
+  logger.info(
+    `Xcode compilation caching is enabled. The cache directory is ${getXcodeCompilationCachePath(derivedDataPath)}.`
+  );
+
+  const pluginXcargs = [
+    'COMPILATION_CACHE_ENABLE_PLUGIN=YES',
+    `COMPILATION_CACHE_PLUGIN_PATH=${plugin.pluginPath}`,
+    // A non-empty remote service path makes Xcode schedule C, Objective-C,
+    // precompiled-module, and precompiled-header cache tasks. The EAS plugin
+    // consumes this option and never opens the path or performs remote I/O.
+    'COMPILATION_CACHE_REMOTE_SERVICE_PATH=/dev/null',
+  ].join(' ');
+
+  return {
+    GYM_XCARGS: [
+      env.GYM_XCARGS,
+      'COMPILATION_CACHE_ENABLE_CACHING=YES COMPILATION_CACHE_ENABLE_DIAGNOSTIC_REMARKS=YES',
+      pluginXcargs,
+    ]
+      .filter(Boolean)
+      .join(' '),
+    GYM_DERIVED_DATA_PATH: derivedDataPath,
+    EAS_XCODE_LOCAL_CAS_APPLE_PLUGIN: plugin.applePluginPath,
+  };
+}

packages/build-tools/src/ios/fastlane.ts

@@ -7,6 +7,7 @@ import os from 'os';
 import path from 'path';
 
 import type { Credentials } from './credentials/manager';
+import * as CompilationCache from './compilationCache';
 import { createFastfileForResigningBuild } from './fastfile';
 import { createGymfileForArchiveBuild, createGymfileForSimulatorBuild } from './gymfile';
 import { isTVOS } from './tvos';
@@ -46,13 +47,18 @@ export async function runFastlaneGym<TJob extends Ios.Job>(
   if (ctx.skipNativeBuild) {
     throw new SkipNativeBuildError('Skipping fastlane build');
   }
+  const compilationCacheEnv = await CompilationCache.prepareXcodeCompilationCacheEnvAsync({
+    derivedDataPath,
+    env: ctx.env,
+    logger: ctx.logger,
+  });
   const buildLogger = new XcodeBuildLogger(ctx.logger, ctx.getReactNativeProjectDirectory());
   void buildLogger.watchLogFiles(ctx.buildLogsDirectory);
   try {
     await runFastlane(['gym'], {
       cwd: workspacePath,
       logger: ctx.logger,
-      env: { ...ctx.env, ...extraEnv },
+      env: { ...ctx.env, ...extraEnv, ...compilationCacheEnv },
     });
   } finally {
     await buildLogger.flush();

packages/build-tools/src/steps/functions/__tests__/xcodeBuildCache.test.ts

@@ -0,0 +1,110 @@
+import { Platform } from '@expo/eas-build-job';
+import { vol } from 'memfs';
+
+import { createMockLogger } from '../../../__tests__/utils/logger';
+import {
+  XCODE_COMPILATION_CACHE_ENV,
+  XCODE_COMPILATION_CACHE_RELATIVE_PATH,
+  compressXcodeCompilationCacheAsync,
+  decompressXcodeCompilationCacheAsync,
+  generateXcodeCompilationCacheKeyAsync,
+} from '../../../ios/compilationCache';
+import { downloadCacheAsync } from '../restoreCache';
+import { restoreXcodeCompilationCacheAsync } from '../restoreBuildCache';
+import { uploadCacheAsync } from '../saveCache';
+import { saveXcodeCompilationCacheAsync } from '../saveBuildCache';
+
+jest.mock('../restoreCache', () => ({
+  downloadCacheAsync: jest.fn(),
+}));
+
+jest.mock('../saveCache', () => ({
+  uploadCacheAsync: jest.fn(),
+}));
+
+jest.mock('../../../ios/compilationCache', () => ({
+  XCODE_COMPILATION_CACHE_ENV: 'EAS_BUILD_XCODE_COMPILATION_CACHE',
+  XCODE_COMPILATION_CACHE_RELATIVE_PATH: 'ios/build/CompilationCache.noindex',
+  compressXcodeCompilationCacheAsync: jest.fn(),
+  decompressXcodeCompilationCacheAsync: jest.fn(),
+  generateXcodeCompilationCacheKeyAsync: jest.fn(),
+}));
+
+const WORKING_DIRECTORY = '/working-directory';
+const ENV = {
+  [XCODE_COMPILATION_CACHE_ENV]: '1',
+  EAS_USE_CACHE: '1',
+  EAS_BUILD_ID: 'build-id',
+  __API_SERVER_URL: 'https://api.expo.test',
+};
+const SECRETS = { robotAccessToken: 'robot-access-token' };
+
+describe('Xcode compilation build cache', () => {
+  beforeEach(() => {
+    jest.mocked(generateXcodeCompilationCacheKeyAsync).mockResolvedValue({
+      key: 'ios-xcode-compilation-cache-version-dependencies',
+      keyPrefix: 'ios-xcode-compilation-cache-version-',
+      xcodeVersion: 'Xcode 26.0 Build version 17A000',
+    });
+  });
+
+  test('restores through the active build cache service', async () => {
+    jest.mocked(downloadCacheAsync).mockResolvedValue({
+      archivePath: '/tmp/cache.tar.gz',
+      matchedKey: 'ios-xcode-compilation-cache-version-dependencies',
+    });
+
+    await restoreXcodeCompilationCacheAsync({
+      logger: createMockLogger(),
+      workingDirectory: WORKING_DIRECTORY,
+      env: ENV,
+      secrets: SECRETS,
+    });
+
+    expect(downloadCacheAsync).toHaveBeenCalledWith(
+      expect.objectContaining({
+        jobId: 'build-id',
+        key: 'ios-xcode-compilation-cache-version-dependencies',
+        keyPrefixes: ['ios-xcode-compilation-cache-version-'],
+        paths: [XCODE_COMPILATION_CACHE_RELATIVE_PATH],
+        platform: Platform.IOS,
+      })
+    );
+    expect(decompressXcodeCompilationCacheAsync).toHaveBeenCalledWith(
+      expect.objectContaining({
+        archivePath: '/tmp/cache.tar.gz',
+        workingDirectory: WORKING_DIRECTORY,
+      })
+    );
+  });
+
+  test('saves through the active build cache service', async () => {
+    vol.fromJSON({ '/tmp/xcode-cache.tar.gz': 'cache' });
+    jest.mocked(compressXcodeCompilationCacheAsync).mockResolvedValue({
+      archivePath: '/tmp/xcode-cache.tar.gz',
+    });
+
+    await saveXcodeCompilationCacheAsync({
+      logger: createMockLogger(),
+      workingDirectory: WORKING_DIRECTORY,
+      env: ENV,
+      secrets: SECRETS,
+    });
+
+    expect(compressXcodeCompilationCacheAsync).toHaveBeenCalledWith(
+      expect.objectContaining({
+        workingDirectory: WORKING_DIRECTORY,
+      })
+    );
+
+    expect(uploadCacheAsync).toHaveBeenCalledWith(
+      expect.objectContaining({
+        jobId: 'build-id',
+        key: 'ios-xcode-compilation-cache-version-dependencies',
+        paths: [XCODE_COMPILATION_CACHE_RELATIVE_PATH],
+        platform: Platform.IOS,
+        size: 5,
+      })
+    );
+  });
+});

packages/build-tools/src/steps/functions/restoreBuildCache.ts

@@ -20,6 +20,12 @@ import {
   getCcachePath,
 } from '../../utils/cacheKey';
 import { Datadog } from '../../datadog';
+import {
+  XCODE_COMPILATION_CACHE_ENV,
+  XCODE_COMPILATION_CACHE_RELATIVE_PATH,
+  decompressXcodeCompilationCacheAsync,
+  generateXcodeCompilationCacheKeyAsync,
+} from '../../ios/compilationCache';
 import { GRADLE_CACHE_KEY_PREFIX, generateGradleCacheKeyAsync } from '../../utils/gradleCacheKey';
 import { TurtleFetchError, turtleFetch } from '../../utils/turtleFetch';
 
@@ -48,26 +54,91 @@ export function createRestoreBuildCacheFunction(): BuildFunction {
         );
       }
 
-      await restoreCcacheAsync({
-        logger,
-        workingDirectory,
-        platform,
-        env,
-        secrets: stepCtx.global.staticContext.job.secrets,
-      });
-
-      if (platform === Platform.ANDROID) {
-        await restoreGradleCacheAsync({
+      await Promise.all([
+        restoreCcacheAsync({
           logger,
           workingDirectory,
+          platform,
           env,
           secrets: stepCtx.global.staticContext.job.secrets,
-        });
-      }
+        }),
+        platform === Platform.IOS
+          ? restoreXcodeCompilationCacheAsync({
+              logger,
+              workingDirectory,
+              env,
+              secrets: stepCtx.global.staticContext.job.secrets,
+            })
+          : restoreGradleCacheAsync({
+              logger,
+              workingDirectory,
+              env,
+              secrets: stepCtx.global.staticContext.job.secrets,
+            }),
+      ]);
     },
   });
 }
 
+export async function restoreXcodeCompilationCacheAsync({
+  logger,
+  workingDirectory,
+  env,
+  secrets,
+}: {
+  logger: bunyan;
+  workingDirectory: string;
+  env: Record<string, string | undefined>;
+  secrets?: { robotAccessToken?: string };
+}): Promise<void> {
+  const buildCacheEnabled =
+    env.EAS_RESTORE_CACHE === '1' || (env.EAS_USE_CACHE === '1' && env.EAS_RESTORE_CACHE !== '0');
+  if (!buildCacheEnabled || env[XCODE_COMPILATION_CACHE_ENV] !== '1') {
+    return;
+  }
+
+  try {
+    const robotAccessToken = nullthrows(
+      secrets?.robotAccessToken,
+      'Robot access token is required for cache operations'
+    );
+    const expoApiServerURL = nullthrows(env.__API_SERVER_URL, '__API_SERVER_URL is not set');
+    const jobId = nullthrows(env.EAS_BUILD_ID, 'EAS_BUILD_ID is not set');
+    const { key, keyPrefix, xcodeVersion } = await generateXcodeCompilationCacheKeyAsync({
+      workingDirectory,
+      env,
+      logger,
+    });
+    logger.info(`Restoring Xcode compilation cache for ${xcodeVersion} with key: ${key}`);
+
+    const { archivePath, matchedKey } = await downloadCacheAsync({
+      logger,
+      jobId,
+      expoApiServerURL,
+      robotAccessToken,
+      paths: [XCODE_COMPILATION_CACHE_RELATIVE_PATH],
+      key,
+      keyPrefixes: [keyPrefix],
+      platform: Platform.IOS,
+    });
+    await decompressXcodeCompilationCacheAsync({
+      archivePath,
+      workingDirectory,
+      env,
+      logger,
+    });
+    logger.info(
+      `Xcode compilation cache restored ${matchedKey === key ? '(direct hit)' : '(prefix match)'}`
+    );
+  } catch (err: unknown) {
+    if (err instanceof TurtleFetchError && err.response?.status === 404) {
+      logger.info('No Xcode compilation cache found for this key');
+    } else {
+      logger.warn({ err }, 'Failed to restore Xcode compilation cache');
+    }
+  }
+}
+
 export function createCacheStatsBuildFunction(): BuildFunction {
   return new BuildFunction({
     namespace: 'eas',

packages/build-tools/src/steps/functions/saveBuildCache.ts

@@ -14,6 +14,12 @@ import os from 'os';
 import path from 'path';
 
 import { compressCacheAsync, uploadCacheAsync } from './saveCache';
+import {
+  XCODE_COMPILATION_CACHE_ENV,
+  XCODE_COMPILATION_CACHE_RELATIVE_PATH,
+  compressXcodeCompilationCacheAsync,
+  generateXcodeCompilationCacheKeyAsync,
+} from '../../ios/compilationCache';
 import { formatBytes } from '../../utils/artifacts';
 import { generateDefaultBuildCacheKeyAsync, getCcachePath } from '../../utils/cacheKey';
 import { generateGradleCacheKeyAsync } from '../../utils/gradleCacheKey';
@@ -43,27 +49,87 @@ export function createSaveBuildCacheFunction(evictUsedBefore: Date): BuildFuncti
         );
       }
 
-      await saveCcacheAsync({
-        logger,
-        workingDirectory,
-        platform,
-        evictUsedBefore,
-        env,
-        secrets: stepCtx.global.staticContext.job.secrets,
-      });
-
-      if (platform === Platform.ANDROID) {
-        await saveGradleCacheAsync({
+      await Promise.all([
+        saveCcacheAsync({
           logger,
           workingDirectory,
+          platform,
+          evictUsedBefore,
           env,
           secrets: stepCtx.global.staticContext.job.secrets,
-        });
-      }
+        }),
+        platform === Platform.IOS
+          ? saveXcodeCompilationCacheAsync({
+              logger,
+              workingDirectory,
+              env,
+              secrets: stepCtx.global.staticContext.job.secrets,
+            })
+          : saveGradleCacheAsync({
+              logger,
+              workingDirectory,
+              env,
+              secrets: stepCtx.global.staticContext.job.secrets,
+            }),
+      ]);
     },
   });
 }
 
+export async function saveXcodeCompilationCacheAsync({
+  logger,
+  workingDirectory,
+  env,
+  secrets,
+}: {
+  logger: bunyan;
+  workingDirectory: string;
+  env: Record<string, string | undefined>;
+  secrets?: { robotAccessToken?: string };
+}): Promise<void> {
+  const buildCacheEnabled =
+    env.EAS_SAVE_CACHE === '1' || (env.EAS_USE_CACHE === '1' && env.EAS_SAVE_CACHE !== '0');
+  if (!buildCacheEnabled || env[XCODE_COMPILATION_CACHE_ENV] !== '1') {
+    return;
+  }
+
+  try {
+    const { key, xcodeVersion } = await generateXcodeCompilationCacheKeyAsync({
+      workingDirectory,
+      env,
+      logger,
+    });
+    logger.info(`Saving Xcode compilation cache for ${xcodeVersion} with key: ${key}`);
+    const jobId = nullthrows(env.EAS_BUILD_ID, 'EAS_BUILD_ID is not set');
+    const robotAccessToken = nullthrows(
+      secrets?.robotAccessToken,
+      'Robot access token is required for cache operations'
+    );
+    const expoApiServerURL = nullthrows(env.__API_SERVER_URL, '__API_SERVER_URL is not set');
+    const { archivePath } = await compressXcodeCompilationCacheAsync({
+      workingDirectory,
+      env,
+      logger,
+    });
+    const { size } = await fs.promises.stat(archivePath);
+    logger.info(`Xcode compilation cache archive size: ${formatBytes(size)}`);
+
+    await uploadCacheAsync({
+      logger,
+      jobId,
+      expoApiServerURL,
+      robotAccessToken,
+      archivePath,
+      key,
+      paths: [XCODE_COMPILATION_CACHE_RELATIVE_PATH],
+      size,
+      platform: Platform.IOS,
+    });
+  } catch (err) {
+    logger.error({ err }, 'Failed to save Xcode compilation cache');
+  }
+}
+
 export async function saveCcacheAsync({
   logger,
   workingDirectory,

packages/build-tools/src/steps/utils/ios/fastlane.ts

@@ -5,6 +5,7 @@ import path from 'path';
 
 import { COMMON_FASTLANE_ENV } from '../../../common/fastlane';
 import { XcodeBuildLogger } from '../../../common/xcpretty';
+import * as CompilationCache from '../../../ios/compilationCache';
 
 export async function runFastlaneGym({
   workingDir,
@@ -19,14 +20,23 @@ export async function runFastlaneGym({
   env: BuildStepEnv;
   extraEnv?: BuildStepEnv;
 }): Promise<void> {
+  const workspacePath = path.join(workingDir, 'ios');
+  const derivedDataPath = path.join(workspacePath, 'build');
+  // When caching is enabled, this also sets GYM_DERIVED_DATA_PATH so Fastlane
+  // and the cache restore/save operations use this exact directory.
+  const compilationCacheEnv = await CompilationCache.prepareXcodeCompilationCacheEnvAsync({
+    derivedDataPath,
+    env,
+    logger,
+  });
   const buildLogger = new XcodeBuildLogger(logger, workingDir);
   void buildLogger.watchLogFiles(buildLogsDirectory);
   try {
     await runFastlane(['gym'], {
-      cwd: path.join(workingDir, 'ios'),
+      cwd: workspacePath,
       logger,
       env,
-      extraEnv,
+      extraEnv: { ...extraEnv, ...compilationCacheEnv },
     });
   } finally {
     await buildLogger.flush();

packages/worker/package.sh

@@ -103,8 +103,8 @@ fi
 
 if [[ "$PLATFORM" == "ios" ]]; then
   record_sim_package_dir="$ROOT_DIR/packages/build-tools/resources/record-sim"
-  record_sim_bin_dir="$target_root_dir/packages/build-tools/bin"
-  mkdir -p "$record_sim_bin_dir"
+  build_tools_bin_dir="$target_root_dir/packages/build-tools/bin"
+  mkdir -p "$build_tools_bin_dir"
   record_sim_bin_path=$(swift build \
     -c release \
     --package-path "$record_sim_package_dir" \
@@ -114,8 +114,18 @@ if [[ "$PLATFORM" == "ios" ]]; then
     -c release \
     --package-path "$record_sim_package_dir" \
     --build-path "$record_sim_build_dir"
-  cp "$record_sim_bin_path/record-sim" "$record_sim_bin_dir/record-sim"
-  chmod +x "$record_sim_bin_dir/record-sim"
+  cp "$record_sim_bin_path/record-sim" "$build_tools_bin_dir/record-sim"
+  chmod +x "$build_tools_bin_dir/record-sim"
+
+  xcrun clang \
+    -arch arm64 \
+    -dynamiclib \
+    -O2 \
+    -Wall \
+    -Wextra \
+    -Werror \
+    -o "$build_tools_bin_dir/libeas_xcode_local_cas_plugin.dylib" \
+    "$ROOT_DIR/packages/build-tools/resources/xcode-local-cache-plugin/eas_local_cas_plugin.c"
 
   # build plugin
   pushd "$ROOT_DIR/packages/expo-cocoapods-proxy" >/dev/null 2>&1