Gated Store Buffer for Precise Virtual Machine Exceptions

The patent introduces a store buffer as an intermediary structure between the execution unit and memory system. This buffer temporarily holds store operations, allowing the execution unit to continue processing instructions without waiting for memory writes to complete. The store buffer acts as a mediator that decouples the timing of store operations from memory access, enabling faster exception handling while maintaining precise exception semantics.

The patent segments the memory system into two distinct parts: a store buffer for temporary store operations and the main memory system for permanent storage. This segmentation allows the system to handle stores asynchronously in the buffer while maintaining simple, straightforward memory access paths for loads and other operations. The segmentation enables fast exception handling by isolating the complexity of store buffering from the rest of the memory subsystem.

The patent implements a dynamic gate control mechanism for the store buffer. The gate is selectively opened or closed based on the current execution state. During normal execution, the gate allows stores to proceed to memory. When an exception is detected, the gate closes to prevent further stores from reaching memory, ensuring precise exception semantics. This dynamic control allows the system to maintain precision only when necessary, minimizing time loss during normal operation.