Revision: 19568
Author: [email protected]
Date: Thu Feb 27 09:36:29 2014 UTC
Log: Implement and enable zapping of code space while sweeping.
[email protected], [email protected]
BUG=
Review URL: https://codereview.chromium.org/181513004
http://code.google.com/p/v8/source/detail?r=19568
Modified:
/branches/bleeding_edge/src/flag-definitions.h
/branches/bleeding_edge/src/mark-compact.cc
=======================================
--- /branches/bleeding_edge/src/flag-definitions.h Wed Feb 26 14:50:58 2014
UTC
+++ /branches/bleeding_edge/src/flag-definitions.h Thu Feb 27 09:36:29 2014
UTC
@@ -572,6 +572,8 @@
DEFINE_bool(use_marking_progress_bar, true,
"Use a progress bar to scan large objects in increments when "
"incremental marking is active.")
+DEFINE_bool(zap_code_space, true,
+ "Zap free memory in code space with 0xCC while sweeping.")
DEFINE_int(random_seed, 0,
"Default seed for initializing random generator "
"(0, the default, means to use system random).")
=======================================
--- /branches/bleeding_edge/src/mark-compact.cc Wed Feb 19 14:03:48 2014 UTC
+++ /branches/bleeding_edge/src/mark-compact.cc Thu Feb 27 09:36:29 2014 UTC
@@ -3204,13 +3204,21 @@
};
+enum FreeSpaceTreatmentMode {
+ IGNORE_FREE_SPACE,
+ ZAP_FREE_SPACE
+};
+
+
// Sweep a space precisely. After this has been done the space can
// be iterated precisely, hitting only the live objects. Code space
// is always swept precisely because we want to be able to iterate
// over it. Map space is swept precisely, because it is not compacted.
// Slots in live objects pointing into evacuation candidates are updated
// if requested.
-template<SweepingMode sweeping_mode, SkipListRebuildingMode skip_list_mode>
+template<SweepingMode sweeping_mode,
+ SkipListRebuildingMode skip_list_mode,
+ FreeSpaceTreatmentMode free_space_mode>
static void SweepPrecisely(PagedSpace* space,
Page* p,
ObjectVisitor* v) {
@@ -3244,6 +3252,9 @@
for ( ; live_objects != 0; live_objects--) {
Address free_end = cell_base + offsets[live_index++] * kPointerSize;
if (free_end != free_start) {
+ if (free_space_mode == ZAP_FREE_SPACE) {
+ memset(free_start, 0xcc, static_cast<int>(free_end -
free_start));
+ }
space->Free(free_start, static_cast<int>(free_end - free_start));
#ifdef ENABLE_GDB_JIT_INTERFACE
if (FLAG_gdbjit && space->identity() == CODE_SPACE) {
@@ -3275,6 +3286,9 @@
*cell = 0;
}
if (free_start != p->area_end()) {
+ if (free_space_mode == ZAP_FREE_SPACE) {
+ memset(free_start, 0xcc, static_cast<int>(p->area_end() -
free_start));
+ }
space->Free(free_start, static_cast<int>(p->area_end() - free_start));
#ifdef ENABLE_GDB_JIT_INTERFACE
if (FLAG_gdbjit && space->identity() == CODE_SPACE) {
@@ -3520,12 +3534,23 @@
SweepConservatively<SWEEP_SEQUENTIALLY>(space, NULL, p);
break;
case OLD_POINTER_SPACE:
- SweepPrecisely<SWEEP_AND_VISIT_LIVE_OBJECTS, IGNORE_SKIP_LIST>(
+ SweepPrecisely<SWEEP_AND_VISIT_LIVE_OBJECTS,
+ IGNORE_SKIP_LIST,
+ IGNORE_FREE_SPACE>(
space, p, &updating_visitor);
break;
case CODE_SPACE:
- SweepPrecisely<SWEEP_AND_VISIT_LIVE_OBJECTS,
REBUILD_SKIP_LIST>(
- space, p, &updating_visitor);
+ if (FLAG_zap_code_space) {
+ SweepPrecisely<SWEEP_AND_VISIT_LIVE_OBJECTS,
+ REBUILD_SKIP_LIST,
+ ZAP_FREE_SPACE>(
+ space, p, &updating_visitor);
+ } else {
+ SweepPrecisely<SWEEP_AND_VISIT_LIVE_OBJECTS,
+ REBUILD_SKIP_LIST,
+ IGNORE_FREE_SPACE>(
+ space, p, &updating_visitor);
+ }
break;
default:
UNREACHABLE();
@@ -4145,10 +4170,15 @@
PrintF("Sweeping 0x%" V8PRIxPTR " precisely.\n",
reinterpret_cast<intptr_t>(p));
}
- if (space->identity() == CODE_SPACE) {
- SweepPrecisely<SWEEP_ONLY, REBUILD_SKIP_LIST>(space, p, NULL);
+ if (space->identity() == CODE_SPACE && FLAG_zap_code_space) {
+ SweepPrecisely<SWEEP_ONLY, REBUILD_SKIP_LIST, ZAP_FREE_SPACE>(
+ space, p, NULL);
+ } else if (space->identity() == CODE_SPACE) {
+ SweepPrecisely<SWEEP_ONLY, REBUILD_SKIP_LIST, IGNORE_FREE_SPACE>(
+ space, p, NULL);
} else {
- SweepPrecisely<SWEEP_ONLY, IGNORE_SKIP_LIST>(space, p, NULL);
+ SweepPrecisely<SWEEP_ONLY, IGNORE_SKIP_LIST, IGNORE_FREE_SPACE>(
+ space, p, NULL);
}
pages_swept++;
break;
--
--
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