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Fix invalid register values in arraycopy_epilogue barrier #216

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Merged
merged 1 commit into from
Apr 20, 2023
Merged

Fix invalid register values in arraycopy_epilogue barrier #216

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32 changes: 32 additions & 0 deletions openjdk/barriers/mmtkObjectBarrier.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -82,9 +82,41 @@ void MMTkObjectBarrierSetAssembler::object_reference_write_post(MacroAssembler*
#endif
}

void MMTkObjectBarrierSetAssembler::arraycopy_prologue(MacroAssembler* masm, DecoratorSet decorators, BasicType type, Register src, Register dst, Register count) {
// `count` or `dst` register values may get overwritten after the array copy, and `arraycopy_epilogue` can receive invalid addresses.
// Save the register values here and restore them in `arraycopy_epilogue`.
// See https://github.com/openjdk/jdk/blob/jdk-11%2B19/src/hotspot/cpu/x86/gc/shared/modRefBarrierSetAssembler_x86.cpp#L37-L50
bool checkcast = (decorators & ARRAYCOPY_CHECKCAST) != 0;
bool disjoint = (decorators & ARRAYCOPY_DISJOINT) != 0;
bool obj_int = type == T_OBJECT LP64_ONLY(&& UseCompressedOops);
if (type == T_OBJECT || type == T_ARRAY) {
if (!checkcast) {
if (!obj_int) {
// Save count for barrier
__ movptr(r11, count);
} else if (disjoint) {
// Save dst in r11 in the disjoint case
__ movq(r11, dst);
}
}
}
}

void MMTkObjectBarrierSetAssembler::arraycopy_epilogue(MacroAssembler* masm, DecoratorSet decorators, BasicType type, Register src, Register dst, Register count) {
bool checkcast = (decorators & ARRAYCOPY_CHECKCAST) != 0;
bool disjoint = (decorators & ARRAYCOPY_DISJOINT) != 0;
bool obj_int = type == T_OBJECT LP64_ONLY(&& UseCompressedOops);
const bool dest_uninitialized = (decorators & IS_DEST_UNINITIALIZED) != 0;
if ((type == T_OBJECT || type == T_ARRAY) && !dest_uninitialized) {
if (!checkcast) {
if (!obj_int) {
// Save count for barrier
count = r11;
} else if (disjoint) {
// Use the saved dst in the disjoint case
dst = r11;
}
}
__ pusha();
__ movptr(c_rarg0, src);
__ movptr(c_rarg1, dst);
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1 change: 1 addition & 0 deletions openjdk/barriers/mmtkObjectBarrier.hpp
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Expand Up @@ -32,6 +32,7 @@ class MMTkObjectBarrierSetAssembler: public MMTkBarrierSetAssembler {
protected:
virtual void object_reference_write_post(MacroAssembler* masm, DecoratorSet decorators, Address dst, Register val, Register tmp1, Register tmp2) const override;
public:
virtual void arraycopy_prologue(MacroAssembler* masm, DecoratorSet decorators, BasicType type, Register src, Register dst, Register count) override;
virtual void arraycopy_epilogue(MacroAssembler* masm, DecoratorSet decorators, BasicType type, Register src, Register dst, Register count) override;
};

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