Future Value Instruction Ordering for Processor Efficiency
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Solution Overview
Problem
Traditional instruction ordering methods limit the reordering or reorganization of instructions, which can hinder processor efficiency by requiring consumer instructions to wait for the results of previously processed instructions, leading to potential pipeline interruptions and processing delays.
Innovation Solution
Implementing future value instruction ordering, where a consumer instruction can be processed before a producer instruction, with the processor allocating a physical location for the value upon processing the consumer instruction and mapping the produced value to that location, allowing for greater flexibility in reordering instructions without violating semantic correctness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional instruction ordering is used where producer instructions must precede consumer instructions, then semantic correctness is maintained, but processor efficiency deteriorates due to pipeline interruptions and processing delays
Solution Approach 1:
The patent inverts the traditional instruction ordering by allowing consumer instructions to be placed before producer instructions in the instruction stream. This is achieved through a renaming mechanism that allocates physical locations for future values and maps them when produced, enabling out-of-order execution while maintaining semantic correctness. The consumer instruction can proceed without waiting for the producer, thus improving processor efficiency while the renaming system ensures the value dependency is properly resolved.
2Productivity
If instructions are reordered to improve processor efficiency, then pipeline interruptions are reduced, but semantic correctness may be violated without proper handling of data dependencies
Solution Approach 1:
The patent introduces a renaming mechanism as an intermediary between the consumer instruction and the producer instruction. When a consumer instruction references a future value, the renamer allocates a new physical location (register) for that value and creates a mapping between the logical reference and the physical location. When the producer instruction executes, it writes to the pre-allocated physical location, ensuring the value is available when the consumer instruction needs it. This intermediary renaming system maintains semantic correctness while enabling instruction reordering.
Solution Approach 2:
The renamer performs preliminary action by pre-allocating physical locations for future values before the producer instruction executes. When the consumer instruction is encountered, the renamer anticipates the future value and reserves a physical location for it. This preliminary allocation allows the consumer instruction to be processed immediately without waiting for the producer, while ensuring the value will be available at the correct location when produced.
3Reliability
If consumer instructions wait for producer instruction results, then data dependency is properly resolved, but processing delays occur reducing overall throughput
Solution Approach 1:
The renamer performs preliminary allocation of physical locations for future values when the consumer instruction is first encountered. Instead of making the consumer wait for the producer to complete, the renamer pre-reserves a physical location and creates a mapping that will be resolved when the producer executes. This eliminates the waiting time for the consumer instruction while ensuring data dependency is properly resolved through the mapping mechanism.
Solution Approach 2:
The patent inverts the traditional approach by allowing the consumer instruction to execute before the producer instruction completes. The renaming mechanism enables this by allocating the physical location at consumer instruction encounter time rather than at producer completion time. The consumer instruction operates on the pre-allocated location, and the producer instruction later writes the actual value to that same location, thus inverting the traditional execution order while maintaining correctness.
Data Source
AI summary
A method of ordering instructions. The method can include placing a first instruction that consumes a value of an object before a second instruction that produces the value of the object such that the first instruction is processed before the second instruction and a physical location is allocated to the value of the object upon processing the first instruction.