🏄 [heap] Add page evacuation mode for new->old

src/flag-definitions.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This file defines all of the flags.  It is separated into different section,
 // for Debug, Release, Logging and Profiling, etc.  To add a new flag, find the
 // correct section, and use one of the DEFINE_ macros, without a trailing ';'.
 //
 // This include does not have a guard, because it is a template-style include,
 // which can be included multiple times in different modes.  It expects to have
@@ skipping 235 matching lines @@
   DEFINE_BOOL(id, true, "enable " #description) \
   DEFINE_NEG_NEG_IMPLICATION(harmony_shipping, id)
 HARMONY_SHIPPING(FLAG_SHIPPING_FEATURES)
 #undef FLAG_SHIPPING_FEATURES
 
 // Flags for experimental implementation features.
 DEFINE_BOOL(compiled_keyed_generic_loads, false,
             "use optimizing compiler to generate keyed generic load stubs")
 DEFINE_BOOL(allocation_site_pretenuring, true,
             "pretenure with allocation sites")
+DEFINE_BOOL(page_evacuation, true, "evacuate pages based on utilization")

[Hannes Payer (out of office), 2016/04/18 12:12:23]

The term evacuation is already used in v8. Evacuation candidates are pages that
will be compacted. We are not going to move objects when this mode is on, we are
moving pages instead.

Better name?
-fast_page_evacuation
-page_promotion

WDYT?

[Michael Lippautz, 2016/04/18 12:57:38]

page_promotion it is

+DEFINE_INT(page_evacuation_threshold, 0,
+           "min percentage of live bytes on a page to enable fast evacuation")
 DEFINE_BOOL(trace_pretenuring, false,
             "trace pretenuring decisions of HAllocate instructions")
 DEFINE_BOOL(trace_pretenuring_statistics, false,
             "trace allocation site pretenuring statistics")
 DEFINE_BOOL(track_fields, true, "track fields with only smi values")
 DEFINE_BOOL(track_double_fields, true, "track fields with double values")
 DEFINE_BOOL(track_heap_object_fields, true, "track fields with heap values")
 DEFINE_BOOL(track_computed_fields, true, "track computed boilerplate fields")
 DEFINE_BOOL(harmony_instanceof_opt, true, "optimize ES6 instanceof support")
 DEFINE_IMPLICATION(track_double_fields, track_fields)
@@ skipping 895 matching lines @@
 #undef DEFINE_ALIAS_FLOAT
 #undef DEFINE_ALIAS_ARGS
 
 #undef FLAG_MODE_DECLARE
 #undef FLAG_MODE_DEFINE
 #undef FLAG_MODE_DEFINE_DEFAULTS
 #undef FLAG_MODE_META
 #undef FLAG_MODE_DEFINE_IMPLICATIONS
 
 #undef COMMA