Why architecture matters here

Valhalla changes performance + semantics. Architecture matters because value semantics + flat layout + specialization together enable a new class of Java code.

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The architecture: every piece explained

The top strip is the core. Value class no identity. Primitive class null-restricted. Flat layout inline in arrays. Generic specialization primitive generics.

The middle row is compatibility. Nullability annotation flavor. Migration existing types. GC + JIT interaction layout aware. Performance cache-line friendly.

The lower rows are practice. Tooling IDE + reflection. Compatibility. Ops — adoption + testing + rollback.

Project Valhalla — value types + primitive classes + generic specialization + flat layoutidentity-free objects for performanceValue classno identityPrimitive classnull-restrictedFlat layoutinline in arraysGeneric specializationprimitive genericsNullabilityflavor annotationMigrationexisting typesGC + JIT interactionlayout awarePerformancecache-line friendlyToolingIDE + reflectionCompatibilitywith prior JDKOps — adoption + testing + rollbackflavormigratelayoutmeasureadoptverifyverifyoperateoperate
Valhalla value types + flat layout + generic specialization.
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End-to-end flow

End-to-end: define Complex as value class. Complex[] stored inline; cache-friendly. Generic List specialized — no boxing. Performance-critical code benefits. Migration path preserves existing types.