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7190310: Inlining WeakReference.get(), and hoisting $referent may lead to non-terminating loops

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In C2 add software membar after load from Reference.referent field to prevent commoning of loads across safepoint since GC can change its value. In C1 always generate Reference.get() intrinsic.

Reviewed-by: roland, twisti, dholmes, johnc
This commit is contained in:
Vladimir Kozlov 2012-08-20 09:58:58 -07:00
parent e3c3c8527e
commit 04c6a7ce10
9 changed files with 333 additions and 300 deletions
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79
hotspot/src/cpu/sparc/vm/c1_CodeStubs_sparc.cpp
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@ -435,85 +435,6 @@ void G1PreBarrierStub::emit_code(LIR_Assembler* ce) {
}
void G1UnsafeGetObjSATBBarrierStub::emit_code(LIR_Assembler* ce) {
// At this point we know that offset == referent_offset.
//
// So we might have to emit:
// if (src == null) goto continuation.
//
// and we definitely have to emit:
// if (klass(src).reference_type == REF_NONE) goto continuation
// if (!marking_active) goto continuation
// if (pre_val == null) goto continuation
// call pre_barrier(pre_val)
// goto continuation
//
__ bind(_entry);
assert(src()->is_register(), "sanity");
Register src_reg = src()->as_register();
if (gen_src_check()) {
// The original src operand was not a constant.
// Generate src == null?
if (__ is_in_wdisp16_range(_continuation)) {
__ br_null(src_reg, /*annul*/false, Assembler::pt, _continuation);
} else {
__ cmp(src_reg, G0);
__ brx(Assembler::equal, false, Assembler::pt, _continuation);
}
__ delayed()->nop();
}
// Generate src->_klass->_reference_type() == REF_NONE)?
assert(tmp()->is_register(), "sanity");
Register tmp_reg = tmp()->as_register();
__ load_klass(src_reg, tmp_reg);
Address ref_type_adr(tmp_reg, instanceKlass::reference_type_offset());
__ ldub(ref_type_adr, tmp_reg);
// _reference_type field is of type ReferenceType (enum)
assert(REF_NONE == 0, "check this code");
__ cmp_zero_and_br(Assembler::equal, tmp_reg, _continuation, /*annul*/false, Assembler::pt);
__ delayed()->nop();
// Is marking active?
assert(thread()->is_register(), "precondition");
Register thread_reg = thread()->as_pointer_register();
Address in_progress(thread_reg, in_bytes(JavaThread::satb_mark_queue_offset() +
PtrQueue::byte_offset_of_active()));
if (in_bytes(PtrQueue::byte_width_of_active()) == 4) {
__ ld(in_progress, tmp_reg);
} else {
assert(in_bytes(PtrQueue::byte_width_of_active()) == 1, "Assumption");
__ ldsb(in_progress, tmp_reg);
}
__ cmp_zero_and_br(Assembler::equal, tmp_reg, _continuation, /*annul*/false, Assembler::pt);
__ delayed()->nop();
// val == null?
assert(val()->is_register(), "Precondition.");
Register val_reg = val()->as_register();
if (__ is_in_wdisp16_range(_continuation)) {
__ br_null(val_reg, /*annul*/false, Assembler::pt, _continuation);
} else {
__ cmp(val_reg, G0);
__ brx(Assembler::equal, false, Assembler::pt, _continuation);
}
__ delayed()->nop();
__ call(Runtime1::entry_for(Runtime1::Runtime1::g1_pre_barrier_slow_id));
__ delayed()->mov(val_reg, G4);
__ br(Assembler::always, false, Assembler::pt, _continuation);
__ delayed()->nop();
}
jbyte* G1PostBarrierStub::_byte_map_base = NULL;
jbyte* G1PostBarrierStub::byte_map_base_slow() {