JDK-8265122 : [lworld] Implement a fast path for flat / null-free array allocation in C1
Type:Enhancement
Component:hotspot
Sub-Component:compiler
Affected Version:repo-valhalla
Priority:P4
Status:Open
Resolution:Unresolved
Submitted:2021-04-13
Updated:2025-05-06
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LIR_Assembler::emit_alloc_array always goes to the slow path for flat / null-free arrays. We should implement a fast path, similar to -XX:+UseFastNewObjectArray.
Comments
New array factory methods look like this and are intrinsified in C2:
static final OneByte[] NULL_FREE_ARRAY_0 = (OneByte[])ValueClass.newNullRestrictedNonAtomicArray(OneByte.class, 2, OneByte.DEFAULT);
static final OneByte[] NULL_FREE_ATOMIC_ARRAY_0 = (OneByte[])ValueClass.newNullRestrictedAtomicArray(OneByte.class, 2, OneByte.DEFAULT);
static final OneByte[] NULLABLE_ARRAY_0 = new OneByte[2];
static final OneByte[] NULLABLE_ATOMIC_ARRAY_0 = (OneByte[])ValueClass.newNullableAtomicArray(OneByte.class, 2);
They should be intrinsified in C1 as well.