jdk-sandbox: comparison src/hotspot/cpu/aarch64/aarch64.ad

equal deleted inserted replaced

-:c3fa35381763
+:91f56aee3928
 //
-// Copyright (c) 2003, 2018, Oracle and/or its affiliates. All rights reserved.
+// Copyright (c) 2003, 2019, Oracle and/or its affiliates. All rights reserved.
-// Copyright (c) 2014, 2018, Red Hat, Inc. All rights reserved.
+// Copyright (c) 2014, 2019, Red Hat, Inc. All rights reserved.
 // DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 //
 // This code is free software; you can redistribute it and/or modify it
 // under the terms of the GNU General Public License version 2 only, as
 // published by the Free Software Foundation.
 if (UseBiasedLocking && !UseOptoBiasInlining) {
 __ biased_locking_enter(box, oop, disp_hdr, tmp, true, cont);
 }
 // Handle existing monitor
-// we can use AArch64's bit test and branch here but
+__ tbnz(disp_hdr, exact_log2(markOopDesc::monitor_value), object_has_monitor);
-// markoopDesc does not define a bit index just the bit value
-// so assert in case the bit pos changes
-#   define __monitor_value_log2 1
-assert(markOopDesc::monitor_value == (1 << __monitor_value_log2), "incorrect bit position");
-__ tbnz(disp_hdr, __monitor_value_log2, object_has_monitor);
-#   undef __monitor_value_log2
 // Set displaced_header to be (markOop of object | UNLOCK_VALUE).
 __ orr(disp_hdr, disp_hdr, markOopDesc::unlocked_value);
 // Load Compare Value application register.
 __ stlxr(tmp, box, oop);
 __ cbzw(tmp, cont);
 __ b(retry_load);
 }
-// Formerly:
-// __ cmpxchgptr(/*oldv=*/disp_hdr,
-//               /*newv=*/box,
-//               /*addr=*/oop,
-//               /*tmp=*/tmp,
-//               cont,
-//               /*fail*/NULL);
 assert(oopDesc::mark_offset_in_bytes() == 0, "offset of _mark is not 0");
 // If the compare-and-exchange succeeded, then we found an unlocked
 // object, will have now locked it will continue at label cont
 __ stlxr(rscratch1, rthread, tmp);
 __ cbnzw(rscratch1, retry_load);
 __ bind(fail);
 }
-// Label next;
+// Store a non-null value into the box to avoid looking like a re-entrant
-// __ cmpxchgptr(/*oldv=*/disp_hdr,
+// lock. The fast-path monitor unlock code checks for
-//               /*newv=*/rthread,
+// markOopDesc::monitor_value so use markOopDesc::unused_mark which has the
-//               /*addr=*/tmp,
+// relevant bit set, and also matches ObjectSynchronizer::slow_enter.
-//               /*tmp=*/rscratch1,
+__ mov(tmp, (address)markOopDesc::unused_mark());
-//               /*succeed*/next,
+__ str(tmp, Address(box, BasicLock::displaced_header_offset_in_bytes()));
-//               /*fail*/NULL);
-// __ bind(next);
-// store a non-null value into the box.
-__ str(box, Address(box, BasicLock::displaced_header_offset_in_bytes()));
-// PPC port checks the following invariants
-// #ifdef ASSERT
-// bne(flag, cont);
-// We have acquired the monitor, check some invariants.
-// addw(/*monitor=*/tmp, tmp, -ObjectMonitor::owner_offset_in_bytes());
-// Invariant 1: _recursions should be 0.
-// assert(ObjectMonitor::recursions_size_in_bytes() == 8, "unexpected size");
-// assert_mem8_is_zero(ObjectMonitor::recursions_offset_in_bytes(), tmp,
-//                        "monitor->_recursions should be 0", -1);
-// Invariant 2: OwnerIsThread shouldn't be 0.
-// assert(ObjectMonitor::OwnerIsThread_size_in_bytes() == 4, "unexpected size");
-//assert_mem4_isnot_zero(ObjectMonitor::OwnerIsThread_offset_in_bytes(), tmp,
-//                           "monitor->OwnerIsThread shouldn't be 0", -1);
-// #endif
 __ bind(cont);
 // flag == EQ indicates success
 // flag == NE indicates failure
+%}
-%}
-// TODO
-// reimplement this with custom cmpxchgptr code
-// which avoids some of the unnecessary branching
 enc_class aarch64_enc_fast_unlock(iRegP object, iRegP box, iRegP tmp, iRegP tmp2) %{
 MacroAssembler _masm(&cbuf);
 Register oop = as_Register($object$$reg);
 Register box = as_Register($box$$reg);
 Register disp_hdr = as_Register($tmp$$reg);
 Register tmp = as_Register($tmp2$$reg);
 Label cont;
 Label object_has_monitor;
-Label cas_failed;
 assert_different_registers(oop, box, tmp, disp_hdr);
 if (UseBiasedLocking && !UseOptoBiasInlining) {
 __ biased_locking_exit(oop, tmp, cont);
 // If the displaced header is 0, we have a recursive unlock.
 __ cmp(disp_hdr, zr);
 __ br(Assembler::EQ, cont);
 // Handle existing monitor.
 __ ldr(tmp, Address(oop, oopDesc::mark_offset_in_bytes()));
 __ tbnz(disp_hdr, exact_log2(markOopDesc::monitor_value), object_has_monitor);
 // Check if it is still a light weight lock, this is is true if we
 // see the stack address of the basicLock in the markOop of the
 // object.
 if (UseLSE) {
 __ mov(tmp, box);
 __ casl(Assembler::xword, tmp, disp_hdr, oop);
 __ cmp(tmp, box);
-} else {
+__ b(cont);
-Label retry_load;
+} else {
-if ((VM_Version::features() & VM_Version::CPU_STXR_PREFETCH))
+Label retry_load;
-__ prfm(Address(oop), PSTL1STRM);
+if ((VM_Version::features() & VM_Version::CPU_STXR_PREFETCH))
-__ bind(retry_load);
+__ prfm(Address(oop), PSTL1STRM);
-__ ldxr(tmp, oop);
+__ bind(retry_load);
-__ cmp(box, tmp);
+__ ldxr(tmp, oop);
-__ br(Assembler::NE, cas_failed);
+__ cmp(box, tmp);
-// use stlxr to ensure update is immediately visible
+__ br(Assembler::NE, cont);
-__ stlxr(tmp, disp_hdr, oop);
+// use stlxr to ensure update is immediately visible
-__ cbzw(tmp, cont);
+__ stlxr(tmp, disp_hdr, oop);
-__ b(retry_load);
+__ cbzw(tmp, cont);
-}
+__ b(retry_load);
+}
-// __ cmpxchgptr(/*compare_value=*/box,
-//               /*exchange_value=*/disp_hdr,
-//               /*where=*/oop,
-//               /*result=*/tmp,
-//               cont,
-//               /*cas_failed*/NULL);
 assert(oopDesc::mark_offset_in_bytes() == 0, "offset of _mark is not 0");
-__ bind(cas_failed);
 // Handle existing monitor.
-__ b(cont);
 __ bind(object_has_monitor);
 __ add(tmp, tmp, -markOopDesc::monitor_value); // monitor
 __ ldr(rscratch1, Address(tmp, ObjectMonitor::owner_offset_in_bytes()));
 __ ldr(disp_hdr, Address(tmp, ObjectMonitor::recursions_offset_in_bytes()));
 __ eor(rscratch1, rscratch1, rthread); // Will be 0 if we are the owner.
 __ orr(rscratch1, rscratch1, disp_hdr); // Will be 0 if both are 0.
 __ cmp(rscratch1, zr);
 __ cbnz(rscratch1, cont);
 // need a release store here
 __ lea(tmp, Address(tmp, ObjectMonitor::owner_offset_in_bytes()));
-__ stlr(rscratch1, tmp); // rscratch1 is zero
+__ stlr(zr, tmp); // set unowned
 __ bind(cont);
 // flag == EQ indicates success
 // flag == NE indicates failure
 %}

changeset 53368	91f56aee3928
parent 53073	11033c4ada54
child 53472	cb43e14dc68b