8232009: Shenandoah: C2 load barrier does not match interpreter version
Reviewed-by: rkennke
--- a/src/hotspot/share/gc/shenandoah/c2/shenandoahBarrierSetC2.cpp Fri Oct 18 09:17:38 2019 -0700
+++ b/src/hotspot/share/gc/shenandoah/c2/shenandoahBarrierSetC2.cpp Fri Oct 18 12:20:51 2019 -0400
@@ -536,9 +536,12 @@
bool mismatched = (decorators & C2_MISMATCHED) != 0;
bool unknown = (decorators & ON_UNKNOWN_OOP_REF) != 0;
bool on_heap = (decorators & IN_HEAP) != 0;
- bool on_weak = (decorators & ON_WEAK_OOP_REF) != 0;
+ bool on_weak_ref = (decorators & (ON_WEAK_OOP_REF | ON_PHANTOM_OOP_REF)) != 0;
bool is_unordered = (decorators & MO_UNORDERED) != 0;
bool need_cpu_mem_bar = !is_unordered || mismatched || !on_heap;
+ bool is_traversal_mode = ShenandoahHeap::heap()->is_traversal_mode();
+ bool keep_alive = (decorators & AS_NO_KEEPALIVE) == 0 || is_traversal_mode;
+ bool in_native = (decorators & IN_NATIVE) != 0;
Node* top = Compile::current()->top();
@@ -547,7 +550,7 @@
if (access.is_oop()) {
if (ShenandoahLoadRefBarrier) {
- load = new ShenandoahLoadReferenceBarrierNode(NULL, load, (decorators & IN_NATIVE) != 0);
+ load = new ShenandoahLoadReferenceBarrierNode(NULL, load, in_native && !is_traversal_mode);
if (access.is_parse_access()) {
load = static_cast<C2ParseAccess &>(access).kit()->gvn().transform(load);
} else {
@@ -563,7 +566,7 @@
// Also we need to add memory barrier to prevent commoning reads
// from this field across safepoint since GC can change its value.
bool need_read_barrier = ShenandoahKeepAliveBarrier &&
- (on_heap && (on_weak || (unknown && offset != top && obj != top)));
+ (on_weak_ref || (unknown && offset != top && obj != top));
if (!access.is_oop() || !need_read_barrier) {
return load;
@@ -573,7 +576,7 @@
C2ParseAccess& parse_access = static_cast<C2ParseAccess&>(access);
GraphKit* kit = parse_access.kit();
- if (on_weak) {
+ if (on_weak_ref && keep_alive) {
// Use the pre-barrier to record the value in the referent field
satb_write_barrier_pre(kit, false /* do_load */,
NULL /* obj */, NULL /* adr */, max_juint /* alias_idx */, NULL /* val */, NULL /* val_type */,