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8376346: [lworld] Shenandoah support #1971

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2509563
Cherry-picked JDK-8376472: Shenandoah: Assembler store barriers read …
shipilev Feb 16, 2026
c395660
Basic Shenandoah support
shipilev Jan 22, 2026
49aa561
Exclude Shenandoah in another EA assert
shipilev Feb 16, 2026
2673c63
Fix include order
shipilev Feb 16, 2026
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1 change: 0 additions & 1 deletion .github/workflows/build-linux.yml
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Original file line number Diff line number Diff line change
Expand Up @@ -143,7 +143,6 @@ jobs:
--with-gtest=${{ steps.gtest.outputs.path }}
--with-zlib=system
--with-jmod-compress=zip-1
--disable-jvm-feature-shenandoahgc
--with-external-symbols-in-bundles=none
--with-native-debug-symbols-level=1
${{ inputs.extra-conf-options }} ${{ inputs.configure-arguments }} || (
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1 change: 0 additions & 1 deletion .github/workflows/build-macos.yml
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Expand Up @@ -110,7 +110,6 @@ jobs:
--with-gtest=${{ steps.gtest.outputs.path }}
--with-zlib=system
--with-jmod-compress=zip-1
--disable-jvm-feature-shenandoahgc
--with-external-symbols-in-bundles=none
--with-native-debug-symbols-level=1
${{ inputs.extra-conf-options }} ${{ inputs.configure-arguments }} || (
Expand Down
1 change: 0 additions & 1 deletion .github/workflows/build-windows.yml
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Expand Up @@ -134,7 +134,6 @@ jobs:
--with-gtest=${{ steps.gtest.outputs.path }}
--with-msvc-toolset-version=${{ inputs.msvc-toolset-version }}
--with-jmod-compress=zip-1
--disable-jvm-feature-shenandoahgc
--with-external-symbols-in-bundles=none
${{ inputs.extra-conf-options }} ${{ inputs.configure-arguments }} || (
echo "Dumping config.log:" &&
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80 changes: 38 additions & 42 deletions src/hotspot/cpu/aarch64/gc/shenandoah/shenandoahBarrierSetAssembler_aarch64.cpp
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Expand Up @@ -85,26 +85,16 @@ void ShenandoahBarrierSetAssembler::arraycopy_epilogue(MacroAssembler* masm, Dec
}
}

void ShenandoahBarrierSetAssembler::shenandoah_write_barrier_pre(MacroAssembler* masm,
Register obj,
Register pre_val,
Register thread,
Register tmp,
bool tosca_live,
bool expand_call) {
if (ShenandoahSATBBarrier) {
satb_write_barrier_pre(masm, obj, pre_val, thread, tmp, rscratch1, tosca_live, expand_call);
}
}
void ShenandoahBarrierSetAssembler::satb_barrier(MacroAssembler* masm,
Register obj,
Register pre_val,
Register thread,
Register tmp1,
Register tmp2,
bool tosca_live,
bool expand_call) {
assert(ShenandoahSATBBarrier, "Should be checked by caller");

void ShenandoahBarrierSetAssembler::satb_write_barrier_pre(MacroAssembler* masm,
Register obj,
Register pre_val,
Register thread,
Register tmp1,
Register tmp2,
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.
Expand Down Expand Up @@ -358,20 +348,20 @@ void ShenandoahBarrierSetAssembler::load_at(MacroAssembler* masm, DecoratorSet d
if (ShenandoahBarrierSet::need_keep_alive_barrier(decorators, type)) {
__ enter(/*strip_ret_addr*/true);
__ push_call_clobbered_registers();
satb_write_barrier_pre(masm /* masm */,
noreg /* obj */,
dst /* pre_val */,
rthread /* thread */,
tmp1 /* tmp1 */,
tmp2 /* tmp2 */,
true /* tosca_live */,
true /* expand_call */);
satb_barrier(masm /* masm */,
noreg /* obj */,
dst /* pre_val */,
rthread /* thread */,
tmp1 /* tmp1 */,
tmp2 /* tmp2 */,
true /* tosca_live */,
true /* expand_call */);
__ pop_call_clobbered_registers();
__ leave();
}
}

void ShenandoahBarrierSetAssembler::store_check(MacroAssembler* masm, Register obj) {
void ShenandoahBarrierSetAssembler::card_barrier(MacroAssembler* masm, Register obj) {
assert(ShenandoahCardBarrier, "Should have been checked by caller");

__ lsr(obj, obj, CardTable::card_shift());
Expand All @@ -394,13 +384,13 @@ 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);
if (!on_oop) {
// 1: non-reference types require no barriers
if (!is_reference_type(type)) {
BarrierSetAssembler::store_at(masm, decorators, type, dst, val, tmp1, tmp2, tmp3);
return;
}

// flatten object address if needed
// Flatten object address right away for simplicity: likely needed by barriers
if (dst.index() == noreg && dst.offset() == 0) {
if (dst.base() != tmp3) {
__ mov(tmp3, dst.base());
Expand All @@ -409,20 +399,26 @@ void ShenandoahBarrierSetAssembler::store_at(MacroAssembler* masm, DecoratorSet
__ lea(tmp3, dst);
}

shenandoah_write_barrier_pre(masm,
tmp3 /* obj */,
tmp2 /* pre_val */,
rthread /* thread */,
tmp1 /* tmp */,
val != noreg /* tosca_live */,
false /* expand_call */);
bool storing_non_null = (val != noreg);

// 2: pre-barrier: SATB needs the previous value
if (ShenandoahBarrierSet::need_satb_barrier(decorators, type)) {
satb_barrier(masm,
tmp3 /* obj */,
tmp2 /* pre_val */,
rthread /* thread */,
tmp1 /* tmp */,
rscratch1 /* tmp2 */,
storing_non_null /* tosca_live */,
false /* expand_call */);
}

// Store!
BarrierSetAssembler::store_at(masm, decorators, type, Address(tmp3, 0), val, noreg, noreg, noreg);

bool in_heap = (decorators & IN_HEAP) != 0;
bool needs_post_barrier = (val != noreg) && in_heap && ShenandoahCardBarrier;
if (needs_post_barrier) {
store_check(masm, tmp3);
// 3: post-barrier: card barrier needs store address
if (ShenandoahBarrierSet::need_card_barrier(decorators, type) && storing_non_null) {
card_barrier(masm, tmp3);
}
}

Expand Down
25 changes: 9 additions & 16 deletions src/hotspot/cpu/aarch64/gc/shenandoah/shenandoahBarrierSetAssembler_aarch64.hpp
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Expand Up @@ -40,23 +40,16 @@ class StubCodeGenerator;
class ShenandoahBarrierSetAssembler: public BarrierSetAssembler {
private:

void satb_write_barrier_pre(MacroAssembler* masm,
Register obj,
Register pre_val,
Register thread,
Register tmp1,
Register tmp2,
bool tosca_live,
bool expand_call);
void shenandoah_write_barrier_pre(MacroAssembler* masm,
Register obj,
Register pre_val,
Register thread,
Register tmp,
bool tosca_live,
bool expand_call);
void satb_barrier(MacroAssembler* masm,
Register obj,
Register pre_val,
Register thread,
Register tmp1,
Register tmp2,
bool tosca_live,
bool expand_call);

void store_check(MacroAssembler* masm, Register obj);
void card_barrier(MacroAssembler* masm, Register obj);

void resolve_forward_pointer(MacroAssembler* masm, Register dst, Register tmp = noreg);
void resolve_forward_pointer_not_null(MacroAssembler* masm, Register dst, Register tmp = noreg);
Expand Down
55 changes: 34 additions & 21 deletions src/hotspot/cpu/ppc/gc/shenandoah/shenandoahBarrierSetAssembler_ppc.cpp
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Expand Up @@ -50,14 +50,14 @@

#define __ masm->

void ShenandoahBarrierSetAssembler::satb_write_barrier(MacroAssembler *masm,
Register base, RegisterOrConstant ind_or_offs,
Register tmp1, Register tmp2, Register tmp3,
MacroAssembler::PreservationLevel preservation_level) {
void ShenandoahBarrierSetAssembler::satb_barrier(MacroAssembler *masm,
Register base, RegisterOrConstant ind_or_offs,
Register tmp1, Register tmp2, Register tmp3,
MacroAssembler::PreservationLevel preservation_level) {
if (ShenandoahSATBBarrier) {
__ block_comment("satb_write_barrier (shenandoahgc) {");
satb_write_barrier_impl(masm, 0, base, ind_or_offs, tmp1, tmp2, tmp3, preservation_level);
__ block_comment("} satb_write_barrier (shenandoahgc)");
__ block_comment("satb_barrier (shenandoahgc) {");
satb_barrier_impl(masm, 0, base, ind_or_offs, tmp1, tmp2, tmp3, preservation_level);
__ block_comment("} satb_barrier (shenandoahgc)");
}
}

Expand Down Expand Up @@ -198,11 +198,12 @@ void ShenandoahBarrierSetAssembler::arraycopy_epilogue(MacroAssembler* masm, Dec
// In "load mode", this register acts as a temporary register and must
// thus not be 'noreg'. In "preloaded mode", its content will be sustained.
// tmp1/tmp2: Temporary registers, one of which must be non-volatile in "preloaded mode".
void ShenandoahBarrierSetAssembler::satb_write_barrier_impl(MacroAssembler *masm, DecoratorSet decorators,
Register base, RegisterOrConstant ind_or_offs,
Register pre_val,
Register tmp1, Register tmp2,
MacroAssembler::PreservationLevel preservation_level) {
void ShenandoahBarrierSetAssembler::satb_barrier_impl(MacroAssembler *masm, DecoratorSet decorators,
Register base, RegisterOrConstant ind_or_offs,
Register pre_val,
Register tmp1, Register tmp2,
MacroAssembler::PreservationLevel preservation_level) {
assert(ShenandoahSATBBarrier, "Should be checked by caller");
assert_different_registers(tmp1, tmp2, pre_val, noreg);

Label skip_barrier;
Expand Down Expand Up @@ -574,13 +575,13 @@ void ShenandoahBarrierSetAssembler::load_at(
if (ShenandoahBarrierSet::need_keep_alive_barrier(decorators, type)) {
if (ShenandoahSATBBarrier) {
__ block_comment("keep_alive_barrier (shenandoahgc) {");
satb_write_barrier_impl(masm, 0, noreg, noreg, dst, tmp1, tmp2, preservation_level);
satb_barrier_impl(masm, 0, noreg, noreg, dst, tmp1, tmp2, preservation_level);
__ block_comment("} keep_alive_barrier (shenandoahgc)");
}
}
}

void ShenandoahBarrierSetAssembler::store_check(MacroAssembler* masm, Register base, RegisterOrConstant ind_or_offs, Register tmp) {
void ShenandoahBarrierSetAssembler::card_barrier(MacroAssembler* masm, Register base, RegisterOrConstant ind_or_offs, Register tmp) {
assert(ShenandoahCardBarrier, "Should have been checked by caller");
assert_different_registers(base, tmp, R0);

Expand All @@ -603,21 +604,33 @@ void ShenandoahBarrierSetAssembler::store_at(MacroAssembler *masm, DecoratorSet
Register base, RegisterOrConstant ind_or_offs, Register val,
Register tmp1, Register tmp2, Register tmp3,
MacroAssembler::PreservationLevel preservation_level) {
if (is_reference_type(type)) {
if (ShenandoahSATBBarrier) {
satb_write_barrier(masm, base, ind_or_offs, tmp1, tmp2, tmp3, preservation_level);
}
// 1: non-reference types require no barriers
if (!is_reference_type(type)) {
BarrierSetAssembler::store_at(masm, decorators, type,
base, ind_or_offs,
val,
tmp1, tmp2, tmp3,
preservation_level);
return;
}

bool storing_non_null = (val != noreg);

// 2: pre-barrier: SATB needs the previous value
if (ShenandoahBarrierSet::need_satb_barrier(decorators, type)) {
satb_barrier(masm, base, ind_or_offs, tmp1, tmp2, tmp3, preservation_level);
}

// Store!
BarrierSetAssembler::store_at(masm, decorators, type,
base, ind_or_offs,
val,
tmp1, tmp2, tmp3,
preservation_level);

// No need for post barrier if storing null
if (ShenandoahCardBarrier && is_reference_type(type) && val != noreg) {
store_check(masm, base, ind_or_offs, tmp1);
// 3: post-barrier: card barrier needs store address
if (ShenandoahBarrierSet::need_card_barrier(decorators, type) && storing_non_null) {
card_barrier(masm, base, ind_or_offs, tmp1);
}
}

Expand Down
24 changes: 12 additions & 12 deletions src/hotspot/cpu/ppc/gc/shenandoah/shenandoahBarrierSetAssembler_ppc.hpp
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Expand Up @@ -45,15 +45,15 @@ class ShenandoahBarrierSetAssembler: public BarrierSetAssembler {
private:

/* ==== Actual barrier implementations ==== */
void satb_write_barrier_impl(MacroAssembler* masm, DecoratorSet decorators,
Register base, RegisterOrConstant ind_or_offs,
Register pre_val,
Register tmp1, Register tmp2,
MacroAssembler::PreservationLevel preservation_level);
void satb_barrier_impl(MacroAssembler* masm, DecoratorSet decorators,
Register base, RegisterOrConstant ind_or_offs,
Register pre_val,
Register tmp1, Register tmp2,
MacroAssembler::PreservationLevel preservation_level);

void store_check(MacroAssembler* masm,
Register base, RegisterOrConstant ind_or_offs,
Register tmp);
void card_barrier(MacroAssembler* masm,
Register base, RegisterOrConstant ind_or_offs,
Register tmp);

void load_reference_barrier_impl(MacroAssembler* masm, DecoratorSet decorators,
Register base, RegisterOrConstant ind_or_offs,
Expand Down Expand Up @@ -85,10 +85,10 @@ class ShenandoahBarrierSetAssembler: public BarrierSetAssembler {
#endif

/* ==== Available barriers (facades of the actual implementations) ==== */
void satb_write_barrier(MacroAssembler* masm,
Register base, RegisterOrConstant ind_or_offs,
Register tmp1, Register tmp2, Register tmp3,
MacroAssembler::PreservationLevel preservation_level);
void satb_barrier(MacroAssembler* masm,
Register base, RegisterOrConstant ind_or_offs,
Register tmp1, Register tmp2, Register tmp3,
MacroAssembler::PreservationLevel preservation_level);

void load_reference_barrier(MacroAssembler* masm, DecoratorSet decorators,
Register base, RegisterOrConstant ind_or_offs,
Expand Down
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