Method and apparatus for facilitating speculative loads in a multiprocessor system

An apparatus that facilitates speculative load operations in a multiprocessor system, comprising:

• a processor;
• an L1 cache coupled to the processor;
• an L2 cache coupled to the L1 cache;
• a load buffer coupled to the processor that maintains a record of speculative load operations that have completed at the processor;
• wherein a speculative load operation is a load operation that is speculatively initiated before a preceding load operation has returned;
• an invalidation signal received at the L1 cache, which indicates that a specific line in the L1 cache is to be invalidated;
• a lookup mechanism that is configured to examine the load buffer to determine if there exists a matching speculative load operation that is completed and is directed to the same location in the L1 cache that the invalidation signal is directed to;
• and
• a replay mechanism, wherein if there exists a matching speculative load operation, the replay mechanism is configured to replay the matching speculative load operation, so that the matching speculative load operation takes place after an event that caused the invalidation signal completes.

A multiprocessor system that facilitates speculative load operations, comprising:

• a plurality of processors;
• a first processor within the plurality of processors;
• an L1 cache coupled to the first processor;
• an L2 cache coupled to the L1 cache;
• a load buffer coupled to the first processor that maintains a record of speculative load operations that have completed at the first processor;
• wherein a speculative load operation is a load operation that is speculatively initiated before a preceding load operation has returned;
• an invalidation signal received at the L1 cache, which indicates that a specific line in the L1 cache is to be invalidated;
• a lookup mechanism that is configured to examine the load buffer to determine if there exists a matching speculative load operation that is completed and is directed to the same location in the L1 cache that the invalidation signal is directed to;
• and
• a replay mechanism, wherein if there exists a matching speculative load operation, the replay mechanism is configured to replay the matching speculative load operation, so that the matching speculative load operation takes place after an event that caused the invalidation signal completes.