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8271925: ZGC: Arraycopy stub passes invalid oop to load barrier
Reviewed-by: neliasso, kvn
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TobiHartmann committed Aug 10, 2021
1 parent 3b899ef commit d53d94b14d09bbcbfd9bbc0d214ead9bd52e7f58
Showing with 9 additions and 6 deletions.
  1. +9 −6 src/hotspot/share/gc/z/c2/zBarrierSetC2.cpp
@@ -300,13 +300,16 @@ void ZBarrierSetC2::clone_at_expansion(PhaseMacroExpand* phase, ArrayCopyNode* a
// BarrierSetC2::clone sets the offsets via BarrierSetC2::arraycopy_payload_base_offset
// which 8-byte aligns them to allow for word size copies. Make sure the offsets point
// to the first element in the array when cloning object arrays. Otherwise, load
// barriers are applied to parts of the header.
// barriers are applied to parts of the header. Also adjust the length accordingly.
assert(src_offset == dest_offset, "should be equal");
assert((src_offset->get_long() == arrayOopDesc::base_offset_in_bytes(T_OBJECT) && UseCompressedClassPointers) ||
(src_offset->get_long() == arrayOopDesc::length_offset_in_bytes() && !UseCompressedClassPointers),
"unexpected offset for object array clone");
src_offset = phase->longcon(arrayOopDesc::base_offset_in_bytes(T_OBJECT));
dest_offset = src_offset;
jlong offset = src_offset->get_long();
if (offset != arrayOopDesc::base_offset_in_bytes(T_OBJECT)) {
assert(!UseCompressedClassPointers, "should only happen without compressed class pointers");
assert((arrayOopDesc::base_offset_in_bytes(T_OBJECT) - offset) == BytesPerLong, "unexpected offset");
length = phase->transform_later(new SubLNode(length, phase->longcon(1))); // Size is in longs
src_offset = phase->longcon(arrayOopDesc::base_offset_in_bytes(T_OBJECT));
dest_offset = src_offset;
}
}
Node* payload_src = phase->basic_plus_adr(src, src_offset);
Node* payload_dst = phase->basic_plus_adr(dest, dest_offset);

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