--- a/hotspot/src/share/vm/code/nmethod.cpp Mon Jul 07 12:37:11 2014 +0200
+++ b/hotspot/src/share/vm/code/nmethod.cpp Mon Jul 07 10:12:40 2014 +0200
@@ -51,6 +51,8 @@
PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
+unsigned char nmethod::_global_unloading_clock = 0;
+
#ifdef DTRACE_ENABLED
// Only bother with this argument setup if dtrace is available
@@ -446,6 +448,7 @@
// Fill in default values for various flag fields
void nmethod::init_defaults() {
_state = in_use;
+ _unloading_clock = 0;
_marked_for_reclamation = 0;
_has_flushed_dependencies = 0;
_has_unsafe_access = 0;
@@ -464,7 +467,11 @@
_oops_do_mark_link = NULL;
_jmethod_id = NULL;
_osr_link = NULL;
- _scavenge_root_link = NULL;
+ if (UseG1GC) {
+ _unloading_next = NULL;
+ } else {
+ _scavenge_root_link = NULL;
+ }
_scavenge_root_state = 0;
_compiler = NULL;
#if INCLUDE_RTM_OPT
@@ -1170,6 +1177,77 @@
}
}
+void nmethod::verify_clean_inline_caches() {
+ assert_locked_or_safepoint(CompiledIC_lock);
+
+ // If the method is not entrant or zombie then a JMP is plastered over the
+ // first few bytes. If an oop in the old code was there, that oop
+ // should not get GC'd. Skip the first few bytes of oops on
+ // not-entrant methods.
+ address low_boundary = verified_entry_point();
+ if (!is_in_use()) {
+ low_boundary += NativeJump::instruction_size;
+ // %%% Note: On SPARC we patch only a 4-byte trap, not a full NativeJump.
+ // This means that the low_boundary is going to be a little too high.
+ // This shouldn't matter, since oops of non-entrant methods are never used.
+ // In fact, why are we bothering to look at oops in a non-entrant method??
+ }
+
+ ResourceMark rm;
+ RelocIterator iter(this, low_boundary);
+ while(iter.next()) {
+ switch(iter.type()) {
+ case relocInfo::virtual_call_type:
+ case relocInfo::opt_virtual_call_type: {
+ CompiledIC *ic = CompiledIC_at(&iter);
+ // Ok, to lookup references to zombies here
+ CodeBlob *cb = CodeCache::find_blob_unsafe(ic->ic_destination());
+ if( cb != NULL && cb->is_nmethod() ) {
+ nmethod* nm = (nmethod*)cb;
+ // Verify that inline caches pointing to both zombie and not_entrant methods are clean
+ if (!nm->is_in_use() || (nm->method()->code() != nm)) {
+ assert(ic->is_clean(), "IC should be clean");
+ }
+ }
+ break;
+ }
+ case relocInfo::static_call_type: {
+ CompiledStaticCall *csc = compiledStaticCall_at(iter.reloc());
+ CodeBlob *cb = CodeCache::find_blob_unsafe(csc->destination());
+ if( cb != NULL && cb->is_nmethod() ) {
+ nmethod* nm = (nmethod*)cb;
+ // Verify that inline caches pointing to both zombie and not_entrant methods are clean
+ if (!nm->is_in_use() || (nm->method()->code() != nm)) {
+ assert(csc->is_clean(), "IC should be clean");
+ }
+ }
+ break;
+ }
+ }
+ }
+}
+
+int nmethod::verify_icholder_relocations() {
+ int count = 0;
+
+ RelocIterator iter(this);
+ while(iter.next()) {
+ if (iter.type() == relocInfo::virtual_call_type) {
+ if (CompiledIC::is_icholder_call_site(iter.virtual_call_reloc())) {
+ CompiledIC *ic = CompiledIC_at(&iter);
+ if (TraceCompiledIC) {
+ tty->print("noticed icholder " INTPTR_FORMAT " ", p2i(ic->cached_icholder()));
+ ic->print();
+ }
+ assert(ic->cached_icholder() != NULL, "must be non-NULL");
+ count++;
+ }
+ }
+ }
+
+ return count;
+}
+
// This is a private interface with the sweeper.
void nmethod::mark_as_seen_on_stack() {
assert(is_alive(), "Must be an alive method");
@@ -1202,6 +1280,23 @@
mdo->inc_decompile_count();
}
+void nmethod::increase_unloading_clock() {
+ _global_unloading_clock++;
+ if (_global_unloading_clock == 0) {
+ // _nmethods are allocated with _unloading_clock == 0,
+ // so 0 is never used as a clock value.
+ _global_unloading_clock = 1;
+ }
+}
+
+void nmethod::set_unloading_clock(unsigned char unloading_clock) {
+ OrderAccess::release_store((volatile jubyte*)&_unloading_clock, unloading_clock);
+}
+
+unsigned char nmethod::unloading_clock() {
+ return (unsigned char)OrderAccess::load_acquire((volatile jubyte*)&_unloading_clock);
+}
+
void nmethod::make_unloaded(BoolObjectClosure* is_alive, oop cause) {
post_compiled_method_unload();
@@ -1247,6 +1342,10 @@
// for later on.
CodeCache::set_needs_cache_clean(true);
}
+
+ // Unregister must be done before the state change
+ Universe::heap()->unregister_nmethod(this);
+
_state = unloaded;
// Log the unloading.
@@ -1590,6 +1689,35 @@
set_unload_reported();
}
+void static clean_ic_if_metadata_is_dead(CompiledIC *ic, BoolObjectClosure *is_alive) {
+ if (ic->is_icholder_call()) {
+ // The only exception is compiledICHolder oops which may
+ // yet be marked below. (We check this further below).
+ CompiledICHolder* cichk_oop = ic->cached_icholder();
+ if (cichk_oop->holder_method()->method_holder()->is_loader_alive(is_alive) &&
+ cichk_oop->holder_klass()->is_loader_alive(is_alive)) {
+ return;
+ }
+ } else {
+ Metadata* ic_oop = ic->cached_metadata();
+ if (ic_oop != NULL) {
+ if (ic_oop->is_klass()) {
+ if (((Klass*)ic_oop)->is_loader_alive(is_alive)) {
+ return;
+ }
+ } else if (ic_oop->is_method()) {
+ if (((Method*)ic_oop)->method_holder()->is_loader_alive(is_alive)) {
+ return;
+ }
+ } else {
+ ShouldNotReachHere();
+ }
+ }
+ }
+
+ ic->set_to_clean();
+}
+
// This is called at the end of the strong tracing/marking phase of a
// GC to unload an nmethod if it contains otherwise unreachable
// oops.
@@ -1633,31 +1761,7 @@
while(iter.next()) {
if (iter.type() == relocInfo::virtual_call_type) {
CompiledIC *ic = CompiledIC_at(&iter);
- if (ic->is_icholder_call()) {
- // The only exception is compiledICHolder oops which may
- // yet be marked below. (We check this further below).
- CompiledICHolder* cichk_oop = ic->cached_icholder();
- if (cichk_oop->holder_method()->method_holder()->is_loader_alive(is_alive) &&
- cichk_oop->holder_klass()->is_loader_alive(is_alive)) {
- continue;
- }
- } else {
- Metadata* ic_oop = ic->cached_metadata();
- if (ic_oop != NULL) {
- if (ic_oop->is_klass()) {
- if (((Klass*)ic_oop)->is_loader_alive(is_alive)) {
- continue;
- }
- } else if (ic_oop->is_method()) {
- if (((Method*)ic_oop)->method_holder()->is_loader_alive(is_alive)) {
- continue;
- }
- } else {
- ShouldNotReachHere();
- }
- }
- }
- ic->set_to_clean();
+ clean_ic_if_metadata_is_dead(ic, is_alive);
}
}
}
@@ -1695,6 +1799,175 @@
verify_metadata_loaders(low_boundary, is_alive);
}
+template <class CompiledICorStaticCall>
+static bool clean_if_nmethod_is_unloaded(CompiledICorStaticCall *ic, address addr, BoolObjectClosure *is_alive, nmethod* from) {
+ // Ok, to lookup references to zombies here
+ CodeBlob *cb = CodeCache::find_blob_unsafe(addr);
+ if (cb != NULL && cb->is_nmethod()) {
+ nmethod* nm = (nmethod*)cb;
+
+ if (nm->unloading_clock() != nmethod::global_unloading_clock()) {
+ // The nmethod has not been processed yet.
+ return true;
+ }
+
+ // Clean inline caches pointing to both zombie and not_entrant methods
+ if (!nm->is_in_use() || (nm->method()->code() != nm)) {
+ ic->set_to_clean();
+ assert(ic->is_clean(), err_msg("nmethod " PTR_FORMAT "not clean %s", from, from->method()->name_and_sig_as_C_string()));
+ }
+ }
+
+ return false;
+}
+
+static bool clean_if_nmethod_is_unloaded(CompiledIC *ic, BoolObjectClosure *is_alive, nmethod* from) {
+ return clean_if_nmethod_is_unloaded(ic, ic->ic_destination(), is_alive, from);
+}
+
+static bool clean_if_nmethod_is_unloaded(CompiledStaticCall *csc, BoolObjectClosure *is_alive, nmethod* from) {
+ return clean_if_nmethod_is_unloaded(csc, csc->destination(), is_alive, from);
+}
+
+bool nmethod::do_unloading_parallel(BoolObjectClosure* is_alive, bool unloading_occurred) {
+ ResourceMark rm;
+
+ // Make sure the oop's ready to receive visitors
+ assert(!is_zombie() && !is_unloaded(),
+ "should not call follow on zombie or unloaded nmethod");
+
+ // If the method is not entrant then a JMP is plastered over the
+ // first few bytes. If an oop in the old code was there, that oop
+ // should not get GC'd. Skip the first few bytes of oops on
+ // not-entrant methods.
+ address low_boundary = verified_entry_point();
+ if (is_not_entrant()) {
+ low_boundary += NativeJump::instruction_size;
+ // %%% Note: On SPARC we patch only a 4-byte trap, not a full NativeJump.
+ // (See comment above.)
+ }
+
+ // The RedefineClasses() API can cause the class unloading invariant
+ // to no longer be true. See jvmtiExport.hpp for details.
+ // Also, leave a debugging breadcrumb in local flag.
+ bool a_class_was_redefined = JvmtiExport::has_redefined_a_class();
+ if (a_class_was_redefined) {
+ // This set of the unloading_occurred flag is done before the
+ // call to post_compiled_method_unload() so that the unloading
+ // of this nmethod is reported.
+ unloading_occurred = true;
+ }
+
+ // Exception cache
+ clean_exception_cache(is_alive);
+
+ bool is_unloaded = false;
+ bool postponed = false;
+
+ RelocIterator iter(this, low_boundary);
+ while(iter.next()) {
+
+ switch (iter.type()) {
+
+ case relocInfo::virtual_call_type:
+ if (unloading_occurred) {
+ // If class unloading occurred we first iterate over all inline caches and
+ // clear ICs where the cached oop is referring to an unloaded klass or method.
+ clean_ic_if_metadata_is_dead(CompiledIC_at(&iter), is_alive);
+ }
+
+ postponed |= clean_if_nmethod_is_unloaded(CompiledIC_at(&iter), is_alive, this);
+ break;
+
+ case relocInfo::opt_virtual_call_type:
+ postponed |= clean_if_nmethod_is_unloaded(CompiledIC_at(&iter), is_alive, this);
+ break;
+
+ case relocInfo::static_call_type:
+ postponed |= clean_if_nmethod_is_unloaded(compiledStaticCall_at(iter.reloc()), is_alive, this);
+ break;
+
+ case relocInfo::oop_type:
+ if (!is_unloaded) {
+ // Unload check
+ oop_Relocation* r = iter.oop_reloc();
+ // Traverse those oops directly embedded in the code.
+ // Other oops (oop_index>0) are seen as part of scopes_oops.
+ assert(1 == (r->oop_is_immediate()) +
+ (r->oop_addr() >= oops_begin() && r->oop_addr() < oops_end()),
+ "oop must be found in exactly one place");
+ if (r->oop_is_immediate() && r->oop_value() != NULL) {
+ if (can_unload(is_alive, r->oop_addr(), unloading_occurred)) {
+ is_unloaded = true;
+ }
+ }
+ }
+ break;
+
+ }
+ }
+
+ if (is_unloaded) {
+ return postponed;
+ }
+
+ // Scopes
+ for (oop* p = oops_begin(); p < oops_end(); p++) {
+ if (*p == Universe::non_oop_word()) continue; // skip non-oops
+ if (can_unload(is_alive, p, unloading_occurred)) {
+ is_unloaded = true;
+ break;
+ }
+ }
+
+ if (is_unloaded) {
+ return postponed;
+ }
+
+ // Ensure that all metadata is still alive
+ verify_metadata_loaders(low_boundary, is_alive);
+
+ return postponed;
+}
+
+void nmethod::do_unloading_parallel_postponed(BoolObjectClosure* is_alive, bool unloading_occurred) {
+ ResourceMark rm;
+
+ // Make sure the oop's ready to receive visitors
+ assert(!is_zombie(),
+ "should not call follow on zombie nmethod");
+
+ // If the method is not entrant then a JMP is plastered over the
+ // first few bytes. If an oop in the old code was there, that oop
+ // should not get GC'd. Skip the first few bytes of oops on
+ // not-entrant methods.
+ address low_boundary = verified_entry_point();
+ if (is_not_entrant()) {
+ low_boundary += NativeJump::instruction_size;
+ // %%% Note: On SPARC we patch only a 4-byte trap, not a full NativeJump.
+ // (See comment above.)
+ }
+
+ RelocIterator iter(this, low_boundary);
+ while(iter.next()) {
+
+ switch (iter.type()) {
+
+ case relocInfo::virtual_call_type:
+ clean_if_nmethod_is_unloaded(CompiledIC_at(&iter), is_alive, this);
+ break;
+
+ case relocInfo::opt_virtual_call_type:
+ clean_if_nmethod_is_unloaded(CompiledIC_at(&iter), is_alive, this);
+ break;
+
+ case relocInfo::static_call_type:
+ clean_if_nmethod_is_unloaded(compiledStaticCall_at(iter.reloc()), is_alive, this);
+ break;
+ }
+ }
+}
+
#ifdef ASSERT
class CheckClass : AllStatic {
@@ -1911,7 +2184,7 @@
assert(cur != NULL, "not NULL-terminated");
nmethod* next = cur->_oops_do_mark_link;
cur->_oops_do_mark_link = NULL;
- cur->fix_oop_relocations();
+ cur->verify_oop_relocations();
NOT_PRODUCT(if (TraceScavenge) cur->print_on(tty, "oops_do, unmark"));
cur = next;
}
@@ -2479,6 +2752,10 @@
};
void nmethod::verify_scavenge_root_oops() {
+ if (UseG1GC) {
+ return;
+ }
+
if (!on_scavenge_root_list()) {
// Actually look inside, to verify the claim that it's clean.
DebugScavengeRoot debug_scavenge_root(this);