src/cpu/x86/vm/x86_32.ad
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*** old/src/cpu/x86/vm/x86_32.ad Thu Feb 13 18:54:11 2014
--- new/src/cpu/x86/vm/x86_32.ad Thu Feb 13 18:54:11 2014
*** 2916,3461 ****
--- 2916,2925 ----
emit_opcode(cbuf,0x83); // SBB hi,0
emit_rm (cbuf,0x3, 0x3, HIGH_FROM_LOW($dst$$reg));
emit_d8 (cbuf,0 );
%}
// Because the transitions from emitted code to the runtime
// monitorenter/exit helper stubs are so slow it's critical that
// we inline both the stack-locking fast-path and the inflated fast path.
//
// See also: cmpFastLock and cmpFastUnlock.
//
// What follows is a specialized inline transliteration of the code
// in slow_enter() and slow_exit(). If we're concerned about I$ bloat
// another option would be to emit TrySlowEnter and TrySlowExit methods
// at startup-time. These methods would accept arguments as
// (rax,=Obj, rbx=Self, rcx=box, rdx=Scratch) and return success-failure
// indications in the icc.ZFlag. Fast_Lock and Fast_Unlock would simply
// marshal the arguments and emit calls to TrySlowEnter and TrySlowExit.
// In practice, however, the # of lock sites is bounded and is usually small.
// Besides the call overhead, TrySlowEnter and TrySlowExit might suffer
// if the processor uses simple bimodal branch predictors keyed by EIP
// Since the helper routines would be called from multiple synchronization
// sites.
//
// An even better approach would be write "MonitorEnter()" and "MonitorExit()"
// in java - using j.u.c and unsafe - and just bind the lock and unlock sites
// to those specialized methods. That'd give us a mostly platform-independent
// implementation that the JITs could optimize and inline at their pleasure.
// Done correctly, the only time we'd need to cross to native could would be
// to park() or unpark() threads. We'd also need a few more unsafe operators
// to (a) prevent compiler-JIT reordering of non-volatile accesses, and
// (b) explicit barriers or fence operations.
//
// TODO:
//
// * Arrange for C2 to pass "Self" into Fast_Lock and Fast_Unlock in one of the registers (scr).
// This avoids manifesting the Self pointer in the Fast_Lock and Fast_Unlock terminals.
// Given TLAB allocation, Self is usually manifested in a register, so passing it into
// the lock operators would typically be faster than reifying Self.
//
// * Ideally I'd define the primitives as:
// fast_lock (nax Obj, nax box, EAX tmp, nax scr) where box, tmp and scr are KILLED.
// fast_unlock (nax Obj, EAX box, nax tmp) where box and tmp are KILLED
// Unfortunately ADLC bugs prevent us from expressing the ideal form.
// Instead, we're stuck with a rather awkward and brittle register assignments below.
// Furthermore the register assignments are overconstrained, possibly resulting in
// sub-optimal code near the synchronization site.
//
// * Eliminate the sp-proximity tests and just use "== Self" tests instead.
// Alternately, use a better sp-proximity test.
//
// * Currently ObjectMonitor._Owner can hold either an sp value or a (THREAD *) value.
// Either one is sufficient to uniquely identify a thread.
// TODO: eliminate use of sp in _owner and use get_thread(tr) instead.
//
// * Intrinsify notify() and notifyAll() for the common cases where the
// object is locked by the calling thread but the waitlist is empty.
// avoid the expensive JNI call to JVM_Notify() and JVM_NotifyAll().
//
// * use jccb and jmpb instead of jcc and jmp to improve code density.
// But beware of excessive branch density on AMD Opterons.
//
// * Both Fast_Lock and Fast_Unlock set the ICC.ZF to indicate success
// or failure of the fast-path. If the fast-path fails then we pass
// control to the slow-path, typically in C. In Fast_Lock and
// Fast_Unlock we often branch to DONE_LABEL, just to find that C2
// will emit a conditional branch immediately after the node.
// So we have branches to branches and lots of ICC.ZF games.
// Instead, it might be better to have C2 pass a "FailureLabel"
// into Fast_Lock and Fast_Unlock. In the case of success, control
// will drop through the node. ICC.ZF is undefined at exit.
// In the case of failure, the node will branch directly to the
// FailureLabel
// obj: object to lock
// box: on-stack box address (displaced header location) - KILLED
// rax,: tmp -- KILLED
// scr: tmp -- KILLED
enc_class Fast_Lock( eRegP obj, eRegP box, eAXRegI tmp, eRegP scr ) %{
Register objReg = as_Register($obj$$reg);
Register boxReg = as_Register($box$$reg);
Register tmpReg = as_Register($tmp$$reg);
Register scrReg = as_Register($scr$$reg);
// Ensure the register assignents are disjoint
guarantee (objReg != boxReg, "") ;
guarantee (objReg != tmpReg, "") ;
guarantee (objReg != scrReg, "") ;
guarantee (boxReg != tmpReg, "") ;
guarantee (boxReg != scrReg, "") ;
guarantee (tmpReg == as_Register(EAX_enc), "") ;
MacroAssembler masm(&cbuf);
if (_counters != NULL) {
masm.atomic_incl(ExternalAddress((address) _counters->total_entry_count_addr()));
}
if (EmitSync & 1) {
// set box->dhw = unused_mark (3)
// Force all sync thru slow-path: slow_enter() and slow_exit()
masm.movptr (Address(boxReg, 0), int32_t(markOopDesc::unused_mark())) ;
masm.cmpptr (rsp, (int32_t)0) ;
} else
if (EmitSync & 2) {
Label DONE_LABEL ;
if (UseBiasedLocking) {
// Note: tmpReg maps to the swap_reg argument and scrReg to the tmp_reg argument.
masm.biased_locking_enter(boxReg, objReg, tmpReg, scrReg, false, DONE_LABEL, NULL, _counters);
}
masm.movptr(tmpReg, Address(objReg, 0)) ; // fetch markword
masm.orptr (tmpReg, 0x1);
masm.movptr(Address(boxReg, 0), tmpReg); // Anticipate successful CAS
if (os::is_MP()) { masm.lock(); }
masm.cmpxchgptr(boxReg, Address(objReg, 0)); // Updates tmpReg
masm.jcc(Assembler::equal, DONE_LABEL);
// Recursive locking
masm.subptr(tmpReg, rsp);
masm.andptr(tmpReg, (int32_t) 0xFFFFF003 );
masm.movptr(Address(boxReg, 0), tmpReg);
masm.bind(DONE_LABEL) ;
} else {
// Possible cases that we'll encounter in fast_lock
// ------------------------------------------------
// * Inflated
// -- unlocked
// -- Locked
// = by self
// = by other
// * biased
// -- by Self
// -- by other
// * neutral
// * stack-locked
// -- by self
// = sp-proximity test hits
// = sp-proximity test generates false-negative
// -- by other
//
Label IsInflated, DONE_LABEL, PopDone ;
// TODO: optimize away redundant LDs of obj->mark and improve the markword triage
// order to reduce the number of conditional branches in the most common cases.
// Beware -- there's a subtle invariant that fetch of the markword
// at [FETCH], below, will never observe a biased encoding (*101b).
// If this invariant is not held we risk exclusion (safety) failure.
if (UseBiasedLocking && !UseOptoBiasInlining) {
masm.biased_locking_enter(boxReg, objReg, tmpReg, scrReg, false, DONE_LABEL, NULL, _counters);
}
masm.movptr(tmpReg, Address(objReg, 0)) ; // [FETCH]
masm.testptr(tmpReg, 0x02) ; // Inflated v (Stack-locked or neutral)
masm.jccb (Assembler::notZero, IsInflated) ;
// Attempt stack-locking ...
masm.orptr (tmpReg, 0x1);
masm.movptr(Address(boxReg, 0), tmpReg); // Anticipate successful CAS
if (os::is_MP()) { masm.lock(); }
masm.cmpxchgptr(boxReg, Address(objReg, 0)); // Updates tmpReg
if (_counters != NULL) {
masm.cond_inc32(Assembler::equal,
ExternalAddress((address)_counters->fast_path_entry_count_addr()));
}
masm.jccb (Assembler::equal, DONE_LABEL);
// Recursive locking
masm.subptr(tmpReg, rsp);
masm.andptr(tmpReg, 0xFFFFF003 );
masm.movptr(Address(boxReg, 0), tmpReg);
if (_counters != NULL) {
masm.cond_inc32(Assembler::equal,
ExternalAddress((address)_counters->fast_path_entry_count_addr()));
}
masm.jmp (DONE_LABEL) ;
masm.bind (IsInflated) ;
// The object is inflated.
//
// TODO-FIXME: eliminate the ugly use of manifest constants:
// Use markOopDesc::monitor_value instead of "2".
// use markOop::unused_mark() instead of "3".
// The tmpReg value is an objectMonitor reference ORed with
// markOopDesc::monitor_value (2). We can either convert tmpReg to an
// objectmonitor pointer by masking off the "2" bit or we can just
// use tmpReg as an objectmonitor pointer but bias the objectmonitor
// field offsets with "-2" to compensate for and annul the low-order tag bit.
//
// I use the latter as it avoids AGI stalls.
// As such, we write "mov r, [tmpReg+OFFSETOF(Owner)-2]"
// instead of "mov r, [tmpReg+OFFSETOF(Owner)]".
//
#define OFFSET_SKEWED(f) ((ObjectMonitor::f ## _offset_in_bytes())-2)
// boxReg refers to the on-stack BasicLock in the current frame.
// We'd like to write:
// set box->_displaced_header = markOop::unused_mark(). Any non-0 value suffices.
// This is convenient but results a ST-before-CAS penalty. The following CAS suffers
// additional latency as we have another ST in the store buffer that must drain.
if (EmitSync & 8192) {
masm.movptr(Address(boxReg, 0), 3) ; // results in ST-before-CAS penalty
masm.get_thread (scrReg) ;
masm.movptr(boxReg, tmpReg); // consider: LEA box, [tmp-2]
masm.movptr(tmpReg, NULL_WORD); // consider: xor vs mov
if (os::is_MP()) { masm.lock(); }
masm.cmpxchgptr(scrReg, Address(boxReg, ObjectMonitor::owner_offset_in_bytes()-2)) ;
} else
if ((EmitSync & 128) == 0) { // avoid ST-before-CAS
masm.movptr(scrReg, boxReg) ;
masm.movptr(boxReg, tmpReg); // consider: LEA box, [tmp-2]
// Using a prefetchw helps avoid later RTS->RTO upgrades and cache probes
if ((EmitSync & 2048) && VM_Version::supports_3dnow_prefetch() && os::is_MP()) {
// prefetchw [eax + Offset(_owner)-2]
masm.prefetchw(Address(rax, ObjectMonitor::owner_offset_in_bytes()-2));
}
if ((EmitSync & 64) == 0) {
// Optimistic form: consider XORL tmpReg,tmpReg
masm.movptr(tmpReg, NULL_WORD) ;
} else {
// Can suffer RTS->RTO upgrades on shared or cold $ lines
// Test-And-CAS instead of CAS
masm.movptr(tmpReg, Address (tmpReg, ObjectMonitor::owner_offset_in_bytes()-2)) ; // rax, = m->_owner
masm.testptr(tmpReg, tmpReg) ; // Locked ?
masm.jccb (Assembler::notZero, DONE_LABEL) ;
}
// Appears unlocked - try to swing _owner from null to non-null.
// Ideally, I'd manifest "Self" with get_thread and then attempt
// to CAS the register containing Self into m->Owner.
// But we don't have enough registers, so instead we can either try to CAS
// rsp or the address of the box (in scr) into &m->owner. If the CAS succeeds
// we later store "Self" into m->Owner. Transiently storing a stack address
// (rsp or the address of the box) into m->owner is harmless.
// Invariant: tmpReg == 0. tmpReg is EAX which is the implicit cmpxchg comparand.
if (os::is_MP()) { masm.lock(); }
masm.cmpxchgptr(scrReg, Address(boxReg, ObjectMonitor::owner_offset_in_bytes()-2)) ;
masm.movptr(Address(scrReg, 0), 3) ; // box->_displaced_header = 3
masm.jccb (Assembler::notZero, DONE_LABEL) ;
masm.get_thread (scrReg) ; // beware: clobbers ICCs
masm.movptr(Address(boxReg, ObjectMonitor::owner_offset_in_bytes()-2), scrReg) ;
masm.xorptr(boxReg, boxReg) ; // set icc.ZFlag = 1 to indicate success
// If the CAS fails we can either retry or pass control to the slow-path.
// We use the latter tactic.
// Pass the CAS result in the icc.ZFlag into DONE_LABEL
// If the CAS was successful ...
// Self has acquired the lock
// Invariant: m->_recursions should already be 0, so we don't need to explicitly set it.
// Intentional fall-through into DONE_LABEL ...
} else {
masm.movptr(Address(boxReg, 0), 3) ; // results in ST-before-CAS penalty
masm.movptr(boxReg, tmpReg) ;
// Using a prefetchw helps avoid later RTS->RTO upgrades and cache probes
if ((EmitSync & 2048) && VM_Version::supports_3dnow_prefetch() && os::is_MP()) {
// prefetchw [eax + Offset(_owner)-2]
masm.prefetchw(Address(rax, ObjectMonitor::owner_offset_in_bytes()-2));
}
if ((EmitSync & 64) == 0) {
// Optimistic form
masm.xorptr (tmpReg, tmpReg) ;
} else {
// Can suffer RTS->RTO upgrades on shared or cold $ lines
masm.movptr(tmpReg, Address (tmpReg, ObjectMonitor::owner_offset_in_bytes()-2)) ; // rax, = m->_owner
masm.testptr(tmpReg, tmpReg) ; // Locked ?
masm.jccb (Assembler::notZero, DONE_LABEL) ;
}
// Appears unlocked - try to swing _owner from null to non-null.
// Use either "Self" (in scr) or rsp as thread identity in _owner.
// Invariant: tmpReg == 0. tmpReg is EAX which is the implicit cmpxchg comparand.
masm.get_thread (scrReg) ;
if (os::is_MP()) { masm.lock(); }
masm.cmpxchgptr(scrReg, Address(boxReg, ObjectMonitor::owner_offset_in_bytes()-2)) ;
// If the CAS fails we can either retry or pass control to the slow-path.
// We use the latter tactic.
// Pass the CAS result in the icc.ZFlag into DONE_LABEL
// If the CAS was successful ...
// Self has acquired the lock
// Invariant: m->_recursions should already be 0, so we don't need to explicitly set it.
// Intentional fall-through into DONE_LABEL ...
}
// DONE_LABEL is a hot target - we'd really like to place it at the
// start of cache line by padding with NOPs.
// See the AMD and Intel software optimization manuals for the
// most efficient "long" NOP encodings.
// Unfortunately none of our alignment mechanisms suffice.
masm.bind(DONE_LABEL);
// Avoid branch-to-branch on AMD processors
// This appears to be superstition.
if (EmitSync & 32) masm.nop() ;
// At DONE_LABEL the icc ZFlag is set as follows ...
// Fast_Unlock uses the same protocol.
// ZFlag == 1 -> Success
// ZFlag == 0 -> Failure - force control through the slow-path
}
%}
// obj: object to unlock
// box: box address (displaced header location), killed. Must be EAX.
// rbx,: killed tmp; cannot be obj nor box.
//
// Some commentary on balanced locking:
//
// Fast_Lock and Fast_Unlock are emitted only for provably balanced lock sites.
// Methods that don't have provably balanced locking are forced to run in the
// interpreter - such methods won't be compiled to use fast_lock and fast_unlock.
// The interpreter provides two properties:
// I1: At return-time the interpreter automatically and quietly unlocks any
// objects acquired the current activation (frame). Recall that the
// interpreter maintains an on-stack list of locks currently held by
// a frame.
// I2: If a method attempts to unlock an object that is not held by the
// the frame the interpreter throws IMSX.
//
// Lets say A(), which has provably balanced locking, acquires O and then calls B().
// B() doesn't have provably balanced locking so it runs in the interpreter.
// Control returns to A() and A() unlocks O. By I1 and I2, above, we know that O
// is still locked by A().
//
// The only other source of unbalanced locking would be JNI. The "Java Native Interface:
// Programmer's Guide and Specification" claims that an object locked by jni_monitorenter
// should not be unlocked by "normal" java-level locking and vice-versa. The specification
// doesn't specify what will occur if a program engages in such mixed-mode locking, however.
enc_class Fast_Unlock( nabxRegP obj, eAXRegP box, eRegP tmp) %{
Register objReg = as_Register($obj$$reg);
Register boxReg = as_Register($box$$reg);
Register tmpReg = as_Register($tmp$$reg);
guarantee (objReg != boxReg, "") ;
guarantee (objReg != tmpReg, "") ;
guarantee (boxReg != tmpReg, "") ;
guarantee (boxReg == as_Register(EAX_enc), "") ;
MacroAssembler masm(&cbuf);
if (EmitSync & 4) {
// Disable - inhibit all inlining. Force control through the slow-path
masm.cmpptr (rsp, 0) ;
} else
if (EmitSync & 8) {
Label DONE_LABEL ;
if (UseBiasedLocking) {
masm.biased_locking_exit(objReg, tmpReg, DONE_LABEL);
}
// classic stack-locking code ...
masm.movptr(tmpReg, Address(boxReg, 0)) ;
masm.testptr(tmpReg, tmpReg) ;
masm.jcc (Assembler::zero, DONE_LABEL) ;
if (os::is_MP()) { masm.lock(); }
masm.cmpxchgptr(tmpReg, Address(objReg, 0)); // Uses EAX which is box
masm.bind(DONE_LABEL);
} else {
Label DONE_LABEL, Stacked, CheckSucc, Inflated ;
// Critically, the biased locking test must have precedence over
// and appear before the (box->dhw == 0) recursive stack-lock test.
if (UseBiasedLocking && !UseOptoBiasInlining) {
masm.biased_locking_exit(objReg, tmpReg, DONE_LABEL);
}
masm.cmpptr(Address(boxReg, 0), 0) ; // Examine the displaced header
masm.movptr(tmpReg, Address(objReg, 0)) ; // Examine the object's markword
masm.jccb (Assembler::zero, DONE_LABEL) ; // 0 indicates recursive stack-lock
masm.testptr(tmpReg, 0x02) ; // Inflated?
masm.jccb (Assembler::zero, Stacked) ;
masm.bind (Inflated) ;
// It's inflated.
// Despite our balanced locking property we still check that m->_owner == Self
// as java routines or native JNI code called by this thread might
// have released the lock.
// Refer to the comments in synchronizer.cpp for how we might encode extra
// state in _succ so we can avoid fetching EntryList|cxq.
//
// I'd like to add more cases in fast_lock() and fast_unlock() --
// such as recursive enter and exit -- but we have to be wary of
// I$ bloat, T$ effects and BP$ effects.
//
// If there's no contention try a 1-0 exit. That is, exit without
// a costly MEMBAR or CAS. See synchronizer.cpp for details on how
// we detect and recover from the race that the 1-0 exit admits.
//
// Conceptually Fast_Unlock() must execute a STST|LDST "release" barrier
// before it STs null into _owner, releasing the lock. Updates
// to data protected by the critical section must be visible before
// we drop the lock (and thus before any other thread could acquire
// the lock and observe the fields protected by the lock).
// IA32's memory-model is SPO, so STs are ordered with respect to
// each other and there's no need for an explicit barrier (fence).
// See also http://gee.cs.oswego.edu/dl/jmm/cookbook.html.
masm.get_thread (boxReg) ;
if ((EmitSync & 4096) && VM_Version::supports_3dnow_prefetch() && os::is_MP()) {
// prefetchw [ebx + Offset(_owner)-2]
masm.prefetchw(Address(rbx, ObjectMonitor::owner_offset_in_bytes()-2));
}
// Note that we could employ various encoding schemes to reduce
// the number of loads below (currently 4) to just 2 or 3.
// Refer to the comments in synchronizer.cpp.
// In practice the chain of fetches doesn't seem to impact performance, however.
if ((EmitSync & 65536) == 0 && (EmitSync & 256)) {
// Attempt to reduce branch density - AMD's branch predictor.
masm.xorptr(boxReg, Address (tmpReg, ObjectMonitor::owner_offset_in_bytes()-2)) ;
masm.orptr(boxReg, Address (tmpReg, ObjectMonitor::recursions_offset_in_bytes()-2)) ;
masm.orptr(boxReg, Address (tmpReg, ObjectMonitor::EntryList_offset_in_bytes()-2)) ;
masm.orptr(boxReg, Address (tmpReg, ObjectMonitor::cxq_offset_in_bytes()-2)) ;
masm.jccb (Assembler::notZero, DONE_LABEL) ;
masm.movptr(Address (tmpReg, ObjectMonitor::owner_offset_in_bytes()-2), NULL_WORD) ;
masm.jmpb (DONE_LABEL) ;
} else {
masm.xorptr(boxReg, Address (tmpReg, ObjectMonitor::owner_offset_in_bytes()-2)) ;
masm.orptr(boxReg, Address (tmpReg, ObjectMonitor::recursions_offset_in_bytes()-2)) ;
masm.jccb (Assembler::notZero, DONE_LABEL) ;
masm.movptr(boxReg, Address (tmpReg, ObjectMonitor::EntryList_offset_in_bytes()-2)) ;
masm.orptr(boxReg, Address (tmpReg, ObjectMonitor::cxq_offset_in_bytes()-2)) ;
masm.jccb (Assembler::notZero, CheckSucc) ;
masm.movptr(Address (tmpReg, ObjectMonitor::owner_offset_in_bytes()-2), NULL_WORD) ;
masm.jmpb (DONE_LABEL) ;
}
// The Following code fragment (EmitSync & 65536) improves the performance of
// contended applications and contended synchronization microbenchmarks.
// Unfortunately the emission of the code - even though not executed - causes regressions
// in scimark and jetstream, evidently because of $ effects. Replacing the code
// with an equal number of never-executed NOPs results in the same regression.
// We leave it off by default.
if ((EmitSync & 65536) != 0) {
Label LSuccess, LGoSlowPath ;
masm.bind (CheckSucc) ;
// Optional pre-test ... it's safe to elide this
if ((EmitSync & 16) == 0) {
masm.cmpptr(Address (tmpReg, ObjectMonitor::succ_offset_in_bytes()-2), 0) ;
masm.jccb (Assembler::zero, LGoSlowPath) ;
}
// We have a classic Dekker-style idiom:
// ST m->_owner = 0 ; MEMBAR; LD m->_succ
// There are a number of ways to implement the barrier:
// (1) lock:andl &m->_owner, 0
// is fast, but mask doesn't currently support the "ANDL M,IMM32" form.
// LOCK: ANDL [ebx+Offset(_Owner)-2], 0
// Encodes as 81 31 OFF32 IMM32 or 83 63 OFF8 IMM8
// (2) If supported, an explicit MFENCE is appealing.
// In older IA32 processors MFENCE is slower than lock:add or xchg
// particularly if the write-buffer is full as might be the case if
// if stores closely precede the fence or fence-equivalent instruction.
// In more modern implementations MFENCE appears faster, however.
// (3) In lieu of an explicit fence, use lock:addl to the top-of-stack
// The $lines underlying the top-of-stack should be in M-state.
// The locked add instruction is serializing, of course.
// (4) Use xchg, which is serializing
// mov boxReg, 0; xchgl boxReg, [tmpReg + Offset(_owner)-2] also works
// (5) ST m->_owner = 0 and then execute lock:orl &m->_succ, 0.
// The integer condition codes will tell us if succ was 0.
// Since _succ and _owner should reside in the same $line and
// we just stored into _owner, it's likely that the $line
// remains in M-state for the lock:orl.
//
// We currently use (3), although it's likely that switching to (2)
// is correct for the future.
masm.movptr(Address (tmpReg, ObjectMonitor::owner_offset_in_bytes()-2), NULL_WORD) ;
if (os::is_MP()) {
if (VM_Version::supports_sse2() && 1 == FenceInstruction) {
masm.mfence();
} else {
masm.lock () ; masm.addptr(Address(rsp, 0), 0) ;
}
}
// Ratify _succ remains non-null
masm.cmpptr(Address (tmpReg, ObjectMonitor::succ_offset_in_bytes()-2), 0) ;
masm.jccb (Assembler::notZero, LSuccess) ;
masm.xorptr(boxReg, boxReg) ; // box is really EAX
if (os::is_MP()) { masm.lock(); }
masm.cmpxchgptr(rsp, Address(tmpReg, ObjectMonitor::owner_offset_in_bytes()-2));
masm.jccb (Assembler::notEqual, LSuccess) ;
// Since we're low on registers we installed rsp as a placeholding in _owner.
// Now install Self over rsp. This is safe as we're transitioning from
// non-null to non=null
masm.get_thread (boxReg) ;
masm.movptr(Address (tmpReg, ObjectMonitor::owner_offset_in_bytes()-2), boxReg) ;
// Intentional fall-through into LGoSlowPath ...
masm.bind (LGoSlowPath) ;
masm.orptr(boxReg, 1) ; // set ICC.ZF=0 to indicate failure
masm.jmpb (DONE_LABEL) ;
masm.bind (LSuccess) ;
masm.xorptr(boxReg, boxReg) ; // set ICC.ZF=1 to indicate success
masm.jmpb (DONE_LABEL) ;
}
masm.bind (Stacked) ;
// It's not inflated and it's not recursively stack-locked and it's not biased.
// It must be stack-locked.
// Try to reset the header to displaced header.
// The "box" value on the stack is stable, so we can reload
// and be assured we observe the same value as above.
masm.movptr(tmpReg, Address(boxReg, 0)) ;
if (os::is_MP()) { masm.lock(); }
masm.cmpxchgptr(tmpReg, Address(objReg, 0)); // Uses EAX which is box
// Intention fall-thru into DONE_LABEL
// DONE_LABEL is a hot target - we'd really like to place it at the
// start of cache line by padding with NOPs.
// See the AMD and Intel software optimization manuals for the
// most efficient "long" NOP encodings.
// Unfortunately none of our alignment mechanisms suffice.
if ((EmitSync & 65536) == 0) {
masm.bind (CheckSucc) ;
}
masm.bind(DONE_LABEL);
// Avoid branch to branch on AMD processors
if (EmitSync & 32768) { masm.nop() ; }
}
%}
enc_class enc_pop_rdx() %{
emit_opcode(cbuf,0x5A);
%}
enc_class enc_rethrow() %{
*** 13155,13181 ****
--- 12619,12648 ----
ins_pipe( pipe_jmp );
%}
// inlined locking and unlocking
instruct cmpFastLock( eFlagsReg cr, eRegP object, eBXRegP box, eAXRegI tmp, eRegP scr) %{
! match( Set cr (FastLock object box) );
effect( TEMP tmp, TEMP scr, USE_KILL box );
+ instruct cmpFastLock(eFlagsReg cr, eRegP object, eBXRegP box, eAXRegI tmp, eRegP scr) %{
+ match(Set cr (FastLock object box));
! effect(TEMP tmp, TEMP scr, USE_KILL box);
ins_cost(300);
format %{ "FASTLOCK $object,$box\t! kills $box,$tmp,$scr" %}
! ins_encode( Fast_Lock(object,box,tmp,scr) );
! ins_pipe( pipe_slow );
! ins_encode %{
! __ fast_lock($object$$Register, $box$$Register, $tmp$$Register, $scr$$Register, _counters);
+ %}
+ ins_pipe(pipe_slow);
%}
- instruct cmpFastUnlock( eFlagsReg cr, eRegP object, eAXRegP box, eRegP tmp ) %{
! match( Set cr (FastUnlock object box) );
! effect( TEMP tmp, USE_KILL box );
! effect(TEMP tmp, USE_KILL box);
ins_cost(300);
format %{ "FASTUNLOCK $object,$box\t! kills $box,$tmp" %}
! ins_encode( Fast_Unlock(object,box,tmp) );
! ins_pipe( pipe_slow );
! ins_encode %{
! __ fast_unlock($object$$Register, $box$$Register, $tmp$$Register);
+ %}
+ ins_pipe(pipe_slow);
%}
// ============================================================================
src/cpu/x86/vm/x86_32.ad
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