Speculative load issue

An apparatus with a load and store buffer arranged to issue a load instruction in a program to a data cache, the load and store buffer comprising:

• a store buffer for storing one or more store instructions;
• and
• a load and store logic unit in communication with the store buffer, the load and store logic unit configured to:
• determine whether there are any unresolved store instructions in the store buffer that are older than the load instruction;
• in response to determining that there is at least one unresolved store instruction in the store buffer older than the load instruction, determining whether the oldest unresolved store instruction in the store buffer is within a speculation window for the load instruction;
• and
• in response to determining that the oldest unresolved store instruction is within the speculation window for the load instruction, speculatively issuing the load instruction to the data cache.

A non-transitory computer readable storage medium having encoded thereon computer readable program code for generating a processor configured to perform a method comprising:

• determining at a load and store logic unit whether there are any unresolved store instructions in a store buffer that are older than the load instruction;
• in response to determining that there is at least one unresolved store instruction in the store buffer older than the load instruction, determining at the load and store logic unit whether the oldest unresolved store instruction in the store buffer is within a speculation window for the load instruction;
• and
• in response to determining that the oldest unresolved store instruction is within the speculation window for the load instruction, speculatively issuing the load instruction to the data cache.