--- a/hotspot/src/share/vm/code/codeCache.cpp Mon Mar 07 21:40:10 2016 +0000
+++ b/hotspot/src/share/vm/code/codeCache.cpp Mon Mar 07 23:06:34 2016 +0000
@@ -637,16 +637,19 @@
}
// Walk the list of methods which might contain non-perm oops.
-void CodeCache::scavenge_root_nmethods_do(CodeBlobClosure* f) {
+void CodeCache::scavenge_root_nmethods_do(CodeBlobToOopClosure* f) {
assert_locked_or_safepoint(CodeCache_lock);
if (UseG1GC) {
return;
}
+ const bool fix_relocations = f->fix_relocations();
debug_only(mark_scavenge_root_nmethods());
- for (nmethod* cur = scavenge_root_nmethods(); cur != NULL; cur = cur->scavenge_root_link()) {
+ nmethod* prev = NULL;
+ nmethod* cur = scavenge_root_nmethods();
+ while (cur != NULL) {
debug_only(cur->clear_scavenge_root_marked());
assert(cur->scavenge_root_not_marked(), "");
assert(cur->on_scavenge_root_list(), "else shouldn't be on this list");
@@ -659,6 +662,18 @@
// Perform cur->oops_do(f), maybe just once per nmethod.
f->do_code_blob(cur);
}
+ nmethod* const next = cur->scavenge_root_link();
+ // The scavengable nmethod list must contain all methods with scavengable
+ // oops. It is safe to include more nmethod on the list, but we do not
+ // expect any live non-scavengable nmethods on the list.
+ if (fix_relocations) {
+ if (!is_live || !cur->detect_scavenge_root_oops()) {
+ unlink_scavenge_root_nmethod(cur, prev);
+ } else {
+ prev = cur;
+ }
+ }
+ cur = next;
}
// Check for stray marks.
@@ -678,6 +693,24 @@
print_trace("add_scavenge_root", nm);
}
+void CodeCache::unlink_scavenge_root_nmethod(nmethod* nm, nmethod* prev) {
+ assert_locked_or_safepoint(CodeCache_lock);
+
+ assert((prev == NULL && scavenge_root_nmethods() == nm) ||
+ (prev != NULL && prev->scavenge_root_link() == nm), "precondition");
+
+ assert(!UseG1GC, "G1 does not use the scavenge_root_nmethods list");
+
+ print_trace("unlink_scavenge_root", nm);
+ if (prev == NULL) {
+ set_scavenge_root_nmethods(nm->scavenge_root_link());
+ } else {
+ prev->set_scavenge_root_link(nm->scavenge_root_link());
+ }
+ nm->set_scavenge_root_link(NULL);
+ nm->clear_on_scavenge_root_list();
+}
+
void CodeCache::drop_scavenge_root_nmethod(nmethod* nm) {
assert_locked_or_safepoint(CodeCache_lock);
@@ -686,20 +719,13 @@
}
print_trace("drop_scavenge_root", nm);
- nmethod* last = NULL;
- nmethod* cur = scavenge_root_nmethods();
- while (cur != NULL) {
- nmethod* next = cur->scavenge_root_link();
+ nmethod* prev = NULL;
+ for (nmethod* cur = scavenge_root_nmethods(); cur != NULL; cur = cur->scavenge_root_link()) {
if (cur == nm) {
- if (last != NULL)
- last->set_scavenge_root_link(next);
- else set_scavenge_root_nmethods(next);
- nm->set_scavenge_root_link(NULL);
- nm->clear_on_scavenge_root_list();
+ unlink_scavenge_root_nmethod(cur, prev);
return;
}
- last = cur;
- cur = next;
+ prev = cur;
}
assert(false, "should have been on list");
}
@@ -728,11 +754,7 @@
} else {
// Prune it from the list, so we don't have to look at it any more.
print_trace("prune_scavenge_root", cur);
- cur->set_scavenge_root_link(NULL);
- cur->clear_on_scavenge_root_list();
- if (last != NULL)
- last->set_scavenge_root_link(next);
- else set_scavenge_root_nmethods(next);
+ unlink_scavenge_root_nmethod(cur, last);
}
cur = next;
}
--- a/hotspot/src/share/vm/code/codeCache.hpp Mon Mar 07 21:40:10 2016 +0000
+++ b/hotspot/src/share/vm/code/codeCache.hpp Mon Mar 07 23:06:34 2016 +0000
@@ -116,6 +116,10 @@
static int allocated_segments();
static size_t freelists_length();
+ static void set_scavenge_root_nmethods(nmethod* nm) { _scavenge_root_nmethods = nm; }
+ static void prune_scavenge_root_nmethods();
+ static void unlink_scavenge_root_nmethod(nmethod* nm, nmethod* prev);
+
public:
// Initialization
static void initialize();
@@ -153,13 +157,17 @@
// to "true" iff some code got unloaded.
static void do_unloading(BoolObjectClosure* is_alive, bool unloading_occurred);
static void asserted_non_scavengable_nmethods_do(CodeBlobClosure* f = NULL) PRODUCT_RETURN;
- static void scavenge_root_nmethods_do(CodeBlobClosure* f);
+
+ // Apply f to every live code blob in scavengable nmethods. Prune nmethods
+ // from the list of scavengable nmethods if f->fix_relocations() and a nmethod
+ // no longer has scavengable oops. If f->fix_relocations(), then f must copy
+ // objects to their new location immediately to avoid fixing nmethods on the
+ // basis of the old object locations.
+ static void scavenge_root_nmethods_do(CodeBlobToOopClosure* f);
static nmethod* scavenge_root_nmethods() { return _scavenge_root_nmethods; }
- static void set_scavenge_root_nmethods(nmethod* nm) { _scavenge_root_nmethods = nm; }
static void add_scavenge_root_nmethod(nmethod* nm);
static void drop_scavenge_root_nmethod(nmethod* nm);
- static void prune_scavenge_root_nmethods();
// Printing/debugging
static void print(); // prints summary
--- a/hotspot/src/share/vm/code/nmethod.cpp Mon Mar 07 21:40:10 2016 +0000
+++ b/hotspot/src/share/vm/code/nmethod.cpp Mon Mar 07 23:06:34 2016 +0000
@@ -1381,7 +1381,6 @@
assert(_method == NULL, "Tautology");
set_osr_link(NULL);
- //set_scavenge_root_link(NULL); // done by prune_scavenge_root_nmethods
NMethodSweeper::report_state_change(this);
}
--- a/hotspot/src/share/vm/gc/parallel/psScavenge.cpp Mon Mar 07 21:40:10 2016 +0000
+++ b/hotspot/src/share/vm/gc/parallel/psScavenge.cpp Mon Mar 07 23:06:34 2016 +0000
@@ -600,12 +600,6 @@
NOT_PRODUCT(reference_processor()->verify_no_references_recorded());
- {
- GCTraceTime(Debug, gc, phases) tm("Prune Scavenge Root Methods", &_gc_timer);
-
- CodeCache::prune_scavenge_root_nmethods();
- }
-
// Re-verify object start arrays
if (VerifyObjectStartArray &&
VerifyAfterGC) {
--- a/hotspot/src/share/vm/gc/shared/genCollectedHeap.cpp Mon Mar 07 21:40:10 2016 +0000
+++ b/hotspot/src/share/vm/gc/shared/genCollectedHeap.cpp Mon Mar 07 23:06:34 2016 +0000
@@ -561,7 +561,7 @@
OopClosure* weak_roots,
CLDClosure* strong_cld_closure,
CLDClosure* weak_cld_closure,
- CodeBlobClosure* code_roots) {
+ CodeBlobToOopClosure* code_roots) {
// General roots.
assert(Threads::thread_claim_parity() != 0, "must have called prologue code");
assert(code_roots != NULL, "code root closure should always be set");
@@ -578,7 +578,7 @@
// Don't process them if they will be processed during the ClassLoaderDataGraph phase.
CLDClosure* roots_from_clds_p = (strong_cld_closure != weak_cld_closure) ? strong_cld_closure : NULL;
// Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
- CodeBlobClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
+ CodeBlobToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
bool is_par = scope->n_threads() > 1;
Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_clds_p, roots_from_code_p);
--- a/hotspot/src/share/vm/gc/shared/genCollectedHeap.hpp Mon Mar 07 21:40:10 2016 +0000
+++ b/hotspot/src/share/vm/gc/shared/genCollectedHeap.hpp Mon Mar 07 23:06:34 2016 +0000
@@ -399,7 +399,7 @@
OopClosure* weak_roots,
CLDClosure* strong_cld_closure,
CLDClosure* weak_cld_closure,
- CodeBlobClosure* code_roots);
+ CodeBlobToOopClosure* code_roots);
public:
static const bool StrongAndWeakRoots = false;
--- a/hotspot/src/share/vm/memory/iterator.hpp Mon Mar 07 21:40:10 2016 +0000
+++ b/hotspot/src/share/vm/memory/iterator.hpp Mon Mar 07 23:06:34 2016 +0000
@@ -285,9 +285,12 @@
protected:
void do_nmethod(nmethod* nm);
public:
+ // If fix_relocations(), then cl must copy objects to their new location immediately to avoid
+ // patching nmethods with the old locations.
CodeBlobToOopClosure(OopClosure* cl, bool fix_relocations) : _cl(cl), _fix_relocations(fix_relocations) {}
virtual void do_code_blob(CodeBlob* cb);
+ bool fix_relocations() const { return _fix_relocations; }
const static bool FixRelocations = true;
};