[fuchsia, arm64] Use mx_cache_flush instead of removed __clear_cache.

runtime/vm/flag_list.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef RUNTIME_VM_FLAG_LIST_H_
 #define RUNTIME_VM_FLAG_LIST_H_
 
 // Don't use USING_DBC outside of this file.
 #if defined(TARGET_ARCH_DBC)
 #define USING_DBC true
 #else
 #define USING_DBC false
 #endif
 
 // Don't use USING_MULTICORE outside of this file.
 #if defined(ARCH_IS_MULTI_CORE)
 #define USING_MULTICORE true
 #else
 #define USING_MULTICORE false
 #endif
 
 // Don't use USING_PRODUCT outside of this file.
 #if defined(PRODUCT)
 #define USING_PRODUCT true
 #else
 #define USING_PRODUCT false
 #endif
 
+// Don't use USING_FUCHSIA outside of this file.
+#if defined(HOST_OS_FUCHSIA)
+#define USING_FUCHSIA true
+#else
+#define USING_FUCHSIA false
+#endif
+
 // List of all flags in the VM.
 // Flags can be one of three categories:
 // * P roduct flags: Can be set in any of the deployment modes, including in
 //   production.
 // * R elease flags: Generally available flags except when building product.
 // * D ebug flags: Can only be set in debug VMs, which also have C++ assertions
 //   enabled.
 // * pre C ompile flags: Generally available flags except when building product
 //   or precompiled runtime.
 //
 // Usage:
 //   P(name, type, default_value, comment)
 //   R(name, product_value, type, default_value, comment)
 //   D(name, type, default_value, comment)
 //   C(name, precompiled_value, product_value, type, default_value, comment)
 #define FLAG_LIST(P, R, D, C)                                                  \
   P(background_compilation, bool, USING_MULTICORE,                             \
     "Run optimizing compilation in background")                                \
   R(background_compilation_stop_alot, false, bool, false,                      \
     "Stress test system: stop background compiler often.")                     \
   R(break_at_isolate_spawn, false, bool, false,                                \
     "Insert a one-time breakpoint at the entrypoint for all spawned isolates") \
-  C(collect_code, false, true, bool, true,                                     \
+  C(collect_code, false, !USING_FUCHSIA, bool, !USING_FUCHSIA,                 \
     "Attempt to GC infrequently used code.")                                   \
   P(collect_dynamic_function_names, bool, true,                                \
     "Collects all dynamic function names to identify unique targets")          \
   R(concurrent_sweep, USING_MULTICORE, bool, USING_MULTICORE,                  \
     "Concurrent sweep for old generation.")                                    \
   R(dedup_instructions, true, bool, false,                                     \
     "Canonicalize instructions when precompiling.")                            \
   C(deoptimize_alot, false, false, bool, false,                                \
     "Deoptimizes we are about to return to Dart code from native entries.")    \
   C(deoptimize_every, 0, 0, int, 0,                                            \
@@ skipping 112 matching lines @@
   P(verbose_gc_hdr, int, 40, "Print verbose GC header interval.")              \
   R(verify_after_gc, false, bool, false,                                       \
     "Enables heap verification after GC.")                                     \
   R(verify_before_gc, false, bool, false,                                      \
     "Enables heap verification before GC.")                                    \
   D(verify_gc_contains, bool, false,                                           \
     "Enables verification of address contains during GC.")                     \
   D(verify_on_transition, bool, false, "Verify on dart <==> VM.")
 
 #endif  // RUNTIME_VM_FLAG_LIST_H_