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8197454: Need Access decorator for storing oop into uninitialized location

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Repurpose ARRAYCOPY_DEST_NOT_INITIALIZED to AS_DEST_NOT_INITIALIZED.

Reviewed-by: eosterlund, coleenp
This commit is contained in:
Kim Barrett 2018-02-13 17:36:22 -05:00
parent eb3ec99500
commit 023fc4b866
5 changed files with 28 additions and 27 deletions
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42
src/hotspot/share/oops/access.hpp
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@ -155,6 +155,8 @@ const DecoratorSet MO_DECORATOR_MASK = MO_UNORDERED | MO_VOLATILE | MO_RELAXED |
// - Accesses on narrowOop* translate to encoded/decoded memory accesses without runtime checks
// - Accesses on HeapWord* translate to a runtime check choosing one of the above
// - Accesses on other types translate to raw memory accesses without runtime checks
// * AS_DEST_NOT_INITIALIZED: This property can be important to e.g. SATB barriers by
// marking that the previous value is uninitialized nonsense rather than a real value.
// * AS_NO_KEEPALIVE: The barrier is used only on oop references and will not keep any involved objects
// alive, regardless of the type of reference being accessed. It will however perform the memory access
// in a consistent way w.r.t. e.g. concurrent compaction, so that the right field is being accessed,
@ -164,10 +166,12 @@ const DecoratorSet MO_DECORATOR_MASK = MO_UNORDERED | MO_VOLATILE | MO_RELAXED |
// responsibility of performing the access and what barriers to be performed to the GC. This is the default.
// Note that primitive accesses will only be resolved on the barrier set if the appropriate build-time
// decorator for enabling primitive barriers is enabled for the build.
const DecoratorSet AS_RAW = UCONST64(1) << 11;
const DecoratorSet AS_NO_KEEPALIVE = UCONST64(1) << 12;
const DecoratorSet AS_NORMAL = UCONST64(1) << 13;
const DecoratorSet AS_DECORATOR_MASK = AS_RAW | AS_NO_KEEPALIVE | AS_NORMAL;
const DecoratorSet AS_RAW = UCONST64(1) << 11;
const DecoratorSet AS_DEST_NOT_INITIALIZED = UCONST64(1) << 12;
const DecoratorSet AS_NO_KEEPALIVE = UCONST64(1) << 13;
const DecoratorSet AS_NORMAL = UCONST64(1) << 14;
const DecoratorSet AS_DECORATOR_MASK = AS_RAW | AS_DEST_NOT_INITIALIZED |
AS_NO_KEEPALIVE | AS_NORMAL;
// === Reference Strength Decorators ===
// These decorators only apply to accesses on oop-like types (oop/narrowOop).
@ -178,10 +182,10 @@ const DecoratorSet AS_DECORATOR_MASK = AS_RAW | AS_NO_KEEPALIVE | AS_NORMAL;
// * ON_UNKNOWN_OOP_REF: The memory access is performed on a reference of unknown strength.
// This could for example come from the unsafe API.
// * Default (no explicit reference strength specified): ON_STRONG_OOP_REF
const DecoratorSet ON_STRONG_OOP_REF = UCONST64(1) << 14;
const DecoratorSet ON_WEAK_OOP_REF = UCONST64(1) << 15;
const DecoratorSet ON_PHANTOM_OOP_REF = UCONST64(1) << 16;
const DecoratorSet ON_UNKNOWN_OOP_REF = UCONST64(1) << 17;
const DecoratorSet ON_STRONG_OOP_REF = UCONST64(1) << 15;
const DecoratorSet ON_WEAK_OOP_REF = UCONST64(1) << 16;
const DecoratorSet ON_PHANTOM_OOP_REF = UCONST64(1) << 17;
const DecoratorSet ON_UNKNOWN_OOP_REF = UCONST64(1) << 18;
const DecoratorSet ON_DECORATOR_MASK = ON_STRONG_OOP_REF | ON_WEAK_OOP_REF |
ON_PHANTOM_OOP_REF | ON_UNKNOWN_OOP_REF;
@ -196,23 +200,21 @@ const DecoratorSet ON_DECORATOR_MASK = ON_STRONG_OOP_REF | ON_WEAK_OOP_REF |
// * IN_CONCURRENT_ROOT: The access is performed in an off-heap data structure pointing into the Java heap,
// but is notably not scanned during safepoints. This is sometimes a special case for some GCs and
// implies that it is also an IN_ROOT.
const DecoratorSet IN_HEAP = UCONST64(1) << 18;
const DecoratorSet IN_HEAP_ARRAY = UCONST64(1) << 19;
const DecoratorSet IN_ROOT = UCONST64(1) << 20;
const DecoratorSet IN_CONCURRENT_ROOT = UCONST64(1) << 21;
const DecoratorSet IN_ARCHIVE_ROOT = UCONST64(1) << 22;
const DecoratorSet IN_HEAP = UCONST64(1) << 19;
const DecoratorSet IN_HEAP_ARRAY = UCONST64(1) << 20;
const DecoratorSet IN_ROOT = UCONST64(1) << 21;
const DecoratorSet IN_CONCURRENT_ROOT = UCONST64(1) << 22;
const DecoratorSet IN_ARCHIVE_ROOT = UCONST64(1) << 23;
const DecoratorSet IN_DECORATOR_MASK = IN_HEAP | IN_HEAP_ARRAY |
IN_ROOT | IN_CONCURRENT_ROOT |
IN_ARCHIVE_ROOT;
// == Value Decorators ==
// * OOP_NOT_NULL: This property can make certain barriers faster such as compressing oops.
const DecoratorSet OOP_NOT_NULL = UCONST64(1) << 23;
const DecoratorSet OOP_NOT_NULL = UCONST64(1) << 24;
const DecoratorSet OOP_DECORATOR_MASK = OOP_NOT_NULL;
// == Arraycopy Decorators ==
// * ARRAYCOPY_DEST_NOT_INITIALIZED: This property can be important to e.g. SATB barriers by
// marking that the previous value uninitialized nonsense rather than a real value.
// * ARRAYCOPY_CHECKCAST: This property means that the class of the objects in source
// are not guaranteed to be subclasses of the class of the destination array. This requires
// a check-cast barrier during the copying operation. If this is not set, it is assumed
@ -222,14 +224,12 @@ const DecoratorSet OOP_DECORATOR_MASK = OOP_NOT_NULL;
// * ARRAYCOPY_ARRAYOF: The copy is in the arrayof form.
// * ARRAYCOPY_ATOMIC: The accesses have to be atomic over the size of its elements.
// * ARRAYCOPY_ALIGNED: The accesses have to be aligned on a HeapWord.
const DecoratorSet ARRAYCOPY_DEST_NOT_INITIALIZED = UCONST64(1) << 24;
const DecoratorSet ARRAYCOPY_CHECKCAST = UCONST64(1) << 25;
const DecoratorSet ARRAYCOPY_DISJOINT = UCONST64(1) << 26;
const DecoratorSet ARRAYCOPY_ARRAYOF = UCONST64(1) << 27;
const DecoratorSet ARRAYCOPY_ATOMIC = UCONST64(1) << 28;
const DecoratorSet ARRAYCOPY_ALIGNED = UCONST64(1) << 29;
const DecoratorSet ARRAYCOPY_DECORATOR_MASK = ARRAYCOPY_DEST_NOT_INITIALIZED |
ARRAYCOPY_CHECKCAST | ARRAYCOPY_DISJOINT |
const DecoratorSet ARRAYCOPY_DECORATOR_MASK = ARRAYCOPY_CHECKCAST | ARRAYCOPY_DISJOINT |
ARRAYCOPY_DISJOINT | ARRAYCOPY_ARRAYOF |
ARRAYCOPY_ATOMIC | ARRAYCOPY_ALIGNED;
@ -343,8 +343,8 @@ class Access: public AllStatic {
template <DecoratorSet expected_mo_decorators>
static void verify_primitive_decorators() {
const DecoratorSet primitive_decorators = (AS_DECORATOR_MASK ^ AS_NO_KEEPALIVE) | IN_HEAP |
IN_HEAP_ARRAY;
const DecoratorSet primitive_decorators = (AS_DECORATOR_MASK ^ AS_NO_KEEPALIVE ^ AS_DEST_NOT_INITIALIZED) |
IN_HEAP | IN_HEAP_ARRAY;
verify_decorators<expected_mo_decorators | primitive_decorators>();
}