Slice construction for pre-executing data dependent loads

An apparatus comprising:

• a processor configured to execute an instruction sequence;
• a slicer of the processor configured to identify a load instruction in the instruction sequence as a first occurrence of a qualified load instruction which will encounter a miss in a last-level cache of a cache hierarchy associated with the processor, wherein the slicer is configured to identify the load instruction as a first occurrence of the qualified load instruction based on a determination that a number of cycles that load instruction is waiting in a load queue of the processor is greater than a number of cycles which will be incurred for the load instruction to be serviced from the last-level cache if there is a hit in the last-level cache for the load data;
• a commit buffer configured to store information pertaining to the first occurrence of the qualified load instruction and shadow instructions which follow the qualified load instruction;
• wherein the slicer is configured to, upon detection of a second occurrence of the qualified load instruction in one of the shadow instructions, construct an instruction slice from the information in the commit buffer to form a slice payload;
• and
• a pre-execution engine configured to pre-execute the instruction slice based on the slice payload to determine an address from which data is to be fetched for execution of a third occurrence of the qualified load instruction;
• and
• a memory controller configured to prefetch the data from the address for the third occurrence of the qualified load instruction.

A non-transitory computer-readable medium comprising code, which, when executed by a computer, causes the computer to perform operations for instruction processing, the non-transitory computer-readable medium comprising:

• code for identifying a load instruction in an instruction sequence executable by a processor as a first occurrence of a qualified load instruction, wherein the code for identifying the load instruction as a first occurrence of the qualified load instruction comprises code for determining that a number of cycles that the load instruction is waiting for load data in a load queue of the processor is greater than a number of cycles which will be incurred in servicing the load instruction from the last-level cache if there is a hit in the last-level cache for the load data;
• code for storing information pertaining to the first occurrence of the qualified load instruction and shadow instructions which follow the qualified load instruction in a commit buffer;
• code for, upon detecting a second occurrence of the qualified load instruction in one of the shadow instructions, constructing an instruction slice from the information in the commit buffer to form a slice payload;
• code for pre-executing the instruction slice based on the slice payload to determine an address from which data is to be fetched for executing a third occurrence of the qualified load instruction;
• and
• code for prefetching the data from the address for the third occurrence of the qualified load instruction.

An apparatus comprising:

• means for identifying a load instruction in an instruction sequence executable by a processor as a first occurrence of a qualified load instruction, wherein the means for identifying the load instruction as a first occurrence of the qualified load instruction comprises means for determining that a number of cycles that the load instruction is waiting for load data in a load queue of the processor is greater than a number of cycles which will be incurred in servicing the load instruction from the last-level cache if there is a hit in the last-level cache for the load data;
• means for storing information pertaining to the first occurrence of the qualified load instruction and shadow instructions which follow the qualified load instruction;
• means for, upon detecting a second occurrence of the qualified load instruction in one of the shadow instructions, constructing an instruction slice from the information in the means for storing to form a slice payload;
• means for pre-executing the instruction slice based on the slice payload to determine an address from which data is to be fetched for executing a third occurrence of the qualified load instruction;
• and
• means for prefetching the data from the address for the third occurrence of the qualified load instruction.