--- a/src/hotspot/share/runtime/mutex.cpp Mon Oct 16 20:22:41 2017 +0000
+++ b/src/hotspot/share/runtime/mutex.cpp Mon Oct 16 22:36:06 2017 -0400
@@ -251,12 +251,6 @@
//
// o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o
-
-// CASPTR() uses the canonical argument order that dominates in the literature.
-// Our internal cmpxchg_ptr() uses a bastardized ordering to accommodate Sun .il templates.
-
-#define CASPTR(a, c, s) \
- intptr_t(Atomic::cmpxchg_ptr((void *)(s), (void *)(a), (void *)(c)))
#define UNS(x) (uintptr_t(x))
#define TRACE(m) \
{ \
@@ -268,6 +262,15 @@
} \
}
+const intptr_t _LBIT = 1;
+
+// Endian-ness ... index of least-significant byte in SplitWord.Bytes[]
+#ifdef VM_LITTLE_ENDIAN
+ #define _LSBINDEX 0
+#else
+ #define _LSBINDEX (sizeof(intptr_t)-1)
+#endif
+
// Simplistic low-quality Marsaglia SHIFT-XOR RNG.
// Bijective except for the trailing mask operation.
// Useful for spin loops as the compiler can't optimize it away.
@@ -297,7 +300,7 @@
intptr_t v = _LockWord.FullWord;
for (;;) {
if ((v & _LBIT) != 0) return 0;
- const intptr_t u = CASPTR(&_LockWord, v, v|_LBIT);
+ const intptr_t u = Atomic::cmpxchg(v|_LBIT, &_LockWord.FullWord, v);
if (v == u) return 1;
v = u;
}
@@ -307,12 +310,12 @@
// Optimistic fast-path form ...
// Fast-path attempt for the common uncontended case.
// Avoid RTS->RTO $ coherence upgrade on typical SMP systems.
- intptr_t v = CASPTR(&_LockWord, 0, _LBIT); // agro ...
+ intptr_t v = Atomic::cmpxchg(_LBIT, &_LockWord.FullWord, (intptr_t)0); // agro ...
if (v == 0) return 1;
for (;;) {
if ((v & _LBIT) != 0) return 0;
- const intptr_t u = CASPTR(&_LockWord, v, v|_LBIT);
+ const intptr_t u = Atomic::cmpxchg(v|_LBIT, &_LockWord.FullWord, v);
if (v == u) return 1;
v = u;
}
@@ -350,7 +353,7 @@
for (;;) {
intptr_t v = _LockWord.FullWord;
if ((v & _LBIT) == 0) {
- if (CASPTR (&_LockWord, v, v|_LBIT) == v) {
+ if (Atomic::cmpxchg (v|_LBIT, &_LockWord.FullWord, v) == v) {
return 1;
}
continue;
@@ -419,13 +422,13 @@
intptr_t v = _LockWord.FullWord;
for (;;) {
if ((v & _LBIT) == 0) {
- const intptr_t u = CASPTR(&_LockWord, v, v|_LBIT);
+ const intptr_t u = Atomic::cmpxchg(v|_LBIT, &_LockWord.FullWord, v);
if (u == v) return 1; // indicate acquired
v = u;
} else {
// Anticipate success ...
ESelf->ListNext = (ParkEvent *)(v & ~_LBIT);
- const intptr_t u = CASPTR(&_LockWord, v, intptr_t(ESelf)|_LBIT);
+ const intptr_t u = Atomic::cmpxchg(intptr_t(ESelf)|_LBIT, &_LockWord.FullWord, v);
if (u == v) return 0; // indicate pushed onto cxq
v = u;
}
@@ -463,7 +466,7 @@
OrderAccess::fence();
// Optional optimization ... try barging on the inner lock
- if ((NativeMonitorFlags & 32) && CASPTR (&_OnDeck, NULL, UNS(ESelf)) == 0) {
+ if ((NativeMonitorFlags & 32) && Atomic::cmpxchg(ESelf, &_OnDeck, (ParkEvent*)NULL) == NULL) {
goto OnDeck_LOOP;
}
@@ -474,7 +477,7 @@
// Only the OnDeck thread can try to acquire -- contend for -- the lock.
// CONSIDER: use Self->OnDeck instead of m->OnDeck.
// Deschedule Self so that others may run.
- while (OrderAccess::load_ptr_acquire(&_OnDeck) != ESelf) {
+ while (OrderAccess::load_acquire(&_OnDeck) != ESelf) {
ParkCommon(ESelf, 0);
}
@@ -570,7 +573,7 @@
// Unlike a normal lock, however, the exiting thread "locks" OnDeck,
// picks a successor and marks that thread as OnDeck. That successor
// thread will then clear OnDeck once it eventually acquires the outer lock.
- if (CASPTR (&_OnDeck, NULL, _LBIT) != UNS(NULL)) {
+ if (Atomic::cmpxchg((ParkEvent*)_LBIT, &_OnDeck, (ParkEvent*)NULL) != NULL) {
return;
}
@@ -585,14 +588,14 @@
assert(RelaxAssert || w != Thread::current()->_MutexEvent, "invariant");
_EntryList = w->ListNext;
// as a diagnostic measure consider setting w->_ListNext = BAD
- assert(UNS(_OnDeck) == _LBIT, "invariant");
+ assert(intptr_t(_OnDeck) == _LBIT, "invariant");
// Pass OnDeck role to w, ensuring that _EntryList has been set first.
// w will clear _OnDeck once it acquires the outer lock.
// Note that once we set _OnDeck that thread can acquire the mutex, proceed
// with its critical section and then enter this code to unlock the mutex. So
// you can have multiple threads active in IUnlock at the same time.
- OrderAccess::release_store_ptr(&_OnDeck, w);
+ OrderAccess::release_store(&_OnDeck, w);
// Another optional optimization ...
// For heavily contended locks it's not uncommon that some other
@@ -616,7 +619,7 @@
for (;;) {
// optional optimization - if locked, the owner is responsible for succession
if (cxq & _LBIT) goto Punt;
- const intptr_t vfy = CASPTR(&_LockWord, cxq, cxq & _LBIT);
+ const intptr_t vfy = Atomic::cmpxchg(cxq & _LBIT, &_LockWord.FullWord, cxq);
if (vfy == cxq) break;
cxq = vfy;
// Interference - LockWord changed - Just retry
@@ -652,7 +655,7 @@
// A thread could have added itself to cxq since this thread previously checked.
// Detect and recover by refetching cxq.
Punt:
- assert(UNS(_OnDeck) == _LBIT, "invariant");
+ assert(intptr_t(_OnDeck) == _LBIT, "invariant");
_OnDeck = NULL; // Release inner lock.
OrderAccess::storeload(); // Dekker duality - pivot point
@@ -693,7 +696,7 @@
const intptr_t v = _LockWord.FullWord;
assert((v & 0xFF) == _LBIT, "invariant");
nfy->ListNext = (ParkEvent *)(v & ~_LBIT);
- if (CASPTR (&_LockWord, v, UNS(nfy)|_LBIT) == v) break;
+ if (Atomic::cmpxchg(intptr_t(nfy)|_LBIT, &_LockWord.FullWord, v) == v) break;
// interference - _LockWord changed -- just retry
}
// Note that setting Notified before pushing nfy onto the cxq is
@@ -840,7 +843,7 @@
// ESelf is now on the cxq, EntryList or at the OnDeck position.
// The following fragment is extracted from Monitor::ILock()
for (;;) {
- if (OrderAccess::load_ptr_acquire(&_OnDeck) == ESelf && TrySpin(Self)) break;
+ if (OrderAccess::load_acquire(&_OnDeck) == ESelf && TrySpin(Self)) break;
ParkCommon(ESelf, 0);
}
assert(_OnDeck == ESelf, "invariant");
@@ -1058,7 +1061,7 @@
// Only the OnDeck thread can try to acquire -- contend for -- the lock.
// CONSIDER: use Self->OnDeck instead of m->OnDeck.
for (;;) {
- if (OrderAccess::load_ptr_acquire(&_OnDeck) == ESelf && TrySpin(NULL)) break;
+ if (OrderAccess::load_acquire(&_OnDeck) == ESelf && TrySpin(NULL)) break;
ParkCommon(ESelf, 0);
}