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Store barrier cleanup

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This commit is contained in:
Aleksey Shipilev 2026-01-27 09:41:03 +01:00
parent 3033e6f421
commit 59f3646f9a
4 changed files with 69 additions and 72 deletions
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54
src/hotspot/cpu/x86/gc/shenandoah/shenandoahBarrierSetAssembler_x86.cpp
View File

@ -174,24 +174,14 @@ void ShenandoahBarrierSetAssembler::arraycopy_epilogue(MacroAssembler* masm, Dec
}
}
void ShenandoahBarrierSetAssembler::shenandoah_write_barrier_pre(MacroAssembler* masm,
void ShenandoahBarrierSetAssembler::satb_barrier(MacroAssembler* masm,
Register obj,
Register pre_val,
Register tmp,
bool tosca_live,
bool expand_call) {
assert(ShenandoahSATBBarrier, "Should be checked by caller");
if (ShenandoahSATBBarrier) {
satb_write_barrier_pre(masm, obj, pre_val, tmp, tosca_live, expand_call);
}
}
void ShenandoahBarrierSetAssembler::satb_write_barrier_pre(MacroAssembler* masm,
Register obj,
Register pre_val,
Register tmp,
bool tosca_live,
bool expand_call) {
// If expand_call is true then we expand the call_VM_leaf macro
// directly to skip generating the check by
// InterpreterMacroAssembler::call_VM_leaf_base that checks _last_sp.
@ -533,7 +523,7 @@ void ShenandoahBarrierSetAssembler::load_at(MacroAssembler* masm, DecoratorSet d
assert_different_registers(dst, tmp1, r15_thread);
// Generate the SATB pre-barrier code to log the value of
// the referent field in an SATB buffer.
shenandoah_write_barrier_pre(masm /* masm */,
satb_barrier(masm,
noreg /* obj */,
dst /* pre_val */,
tmp1 /* tmp */,
@ -544,7 +534,7 @@ void ShenandoahBarrierSetAssembler::load_at(MacroAssembler* masm, DecoratorSet d
}
}
void ShenandoahBarrierSetAssembler::store_check(MacroAssembler* masm, Register obj) {
void ShenandoahBarrierSetAssembler::card_barrier(MacroAssembler* masm, Register obj) {
assert(ShenandoahCardBarrier, "Should have been checked by caller");
// Does a store check for the oop in register obj. The content of
@ -575,14 +565,15 @@ void ShenandoahBarrierSetAssembler::store_check(MacroAssembler* masm, Register o
void ShenandoahBarrierSetAssembler::store_at(MacroAssembler* masm, DecoratorSet decorators, BasicType type,
Address dst, Register val, Register tmp1, Register tmp2, Register tmp3) {
bool on_oop = is_reference_type(type);
bool in_heap = (decorators & IN_HEAP) != 0;
bool as_normal = (decorators & AS_NORMAL) != 0;
if (on_oop && in_heap) {
bool needs_pre_barrier = as_normal;
// 1: non-reference type, no barrier is needed
if (!is_reference_type(type)) {
BarrierSetAssembler::store_at(masm, decorators, type, dst, val, tmp1, tmp2, tmp3);
return;
}
// Flatten object address right away for simplicity: likely needed by barriers
assert_different_registers(val, tmp1, tmp2, tmp3, r15_thread);
// flatten object address if needed
// We do it regardless of precise because we need the registers
if (dst.index() == noreg && dst.disp() == 0) {
if (dst.base() != tmp1) {
__ movptr(tmp1, dst.base());
@ -591,25 +582,24 @@ void ShenandoahBarrierSetAssembler::store_at(MacroAssembler* masm, DecoratorSet
__ lea(tmp1, dst);
}
assert_different_registers(val, tmp1, tmp2, tmp3, r15_thread);
bool storing_non_null = (val != noreg);
if (needs_pre_barrier) {
shenandoah_write_barrier_pre(masm /*masm*/,
// 2: pre-barrier: SATB needs the previous value
if (ShenandoahBarrierSet::need_satb_barrier(decorators, type)) {
satb_barrier(masm,
tmp1 /* obj */,
tmp2 /* pre_val */,
tmp3 /* tmp */,
val != noreg /* tosca_live */,
storing_non_null /* tosca_live */,
false /* expand_call */);
}
// Store!
BarrierSetAssembler::store_at(masm, decorators, type, Address(tmp1, 0), val, noreg, noreg, noreg);
if (val != noreg) {
if (ShenandoahCardBarrier) {
store_check(masm, tmp1);
}
}
} else {
BarrierSetAssembler::store_at(masm, decorators, type, dst, val, tmp1, tmp2, tmp3);
// 3: post-barrier: card barrier needs store address
if (ShenandoahBarrierSet::need_card_barrier(decorators, type) && storing_non_null) {
card_barrier(masm, tmp1);
}
}

11
src/hotspot/cpu/x86/gc/shenandoah/shenandoahBarrierSetAssembler_x86.hpp
View File

@ -41,21 +41,14 @@ class StubCodeGenerator;
class ShenandoahBarrierSetAssembler: public BarrierSetAssembler {
private:
void satb_write_barrier_pre(MacroAssembler* masm,
void satb_barrier(MacroAssembler* masm,
Register obj,
Register pre_val,
Register tmp,
bool tosca_live,
bool expand_call);
void shenandoah_write_barrier_pre(MacroAssembler* masm,
Register obj,
Register pre_val,
Register tmp,
bool tosca_live,
bool expand_call);
void store_check(MacroAssembler* masm, Register obj);
void card_barrier(MacroAssembler* masm, Register obj);
void gen_write_ref_array_post_barrier(MacroAssembler* masm, DecoratorSet decorators,
Register addr, Register count,

16
src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.cpp
View File

@ -72,13 +72,11 @@ void ShenandoahBarrierSet::print_on(outputStream* st) const {
bool ShenandoahBarrierSet::need_load_reference_barrier(DecoratorSet decorators, BasicType type) {
if (!ShenandoahLoadRefBarrier) return false;
// Only needed for references
return is_reference_type(type);
}
bool ShenandoahBarrierSet::need_keep_alive_barrier(DecoratorSet decorators, BasicType type) {
if (!ShenandoahSATBBarrier) return false;
// Only needed for references
if (!is_reference_type(type)) return false;
bool keep_alive = (decorators & AS_NO_KEEPALIVE) == 0;
@ -87,6 +85,20 @@ bool ShenandoahBarrierSet::need_keep_alive_barrier(DecoratorSet decorators, Basi
return (on_weak_ref || unknown) && keep_alive;
}
bool ShenandoahBarrierSet::need_satb_barrier(DecoratorSet decorators, BasicType type) {
if (!ShenandoahSATBBarrier) return false;
if (!is_reference_type(type)) return false;
bool dest_initialized = (decorators & IS_DEST_UNINITIALIZED) == 0;
return dest_initialized;
}
bool ShenandoahBarrierSet::need_card_barrier(DecoratorSet decorators, BasicType type) {
if (!ShenandoahCardBarrier) return false;
if (!is_reference_type(type)) return false;
bool in_heap = (decorators & IN_HEAP) != 0;
return in_heap;
}
void ShenandoahBarrierSet::on_slowpath_allocation_exit(JavaThread* thread, oop new_obj) {
#if COMPILER2_OR_JVMCI
if (ReduceInitialCardMarks && ShenandoahCardBarrier && !ShenandoahHeap::heap()->is_in_young(new_obj)) {

2
src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.hpp
View File

@ -60,6 +60,8 @@ public:
static bool need_load_reference_barrier(DecoratorSet decorators, BasicType type);
static bool need_keep_alive_barrier(DecoratorSet decorators, BasicType type);
static bool need_satb_barrier(DecoratorSet decorators, BasicType type);
static bool need_card_barrier(DecoratorSet decorators, BasicType type);
static bool is_strong_access(DecoratorSet decorators) {
return (decorators & (ON_WEAK_OOP_REF | ON_PHANTOM_OOP_REF)) == 0;