Compiler List Scheduler Dynamic Instruction Sequence Selection
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Solution Overview
Problem
The challenge in software processing is selecting an optimal instruction sequence for computations, as existing methods fail to determine the most efficient sequence a priori, especially due to varying hardware resource utilization and constraints, leading to suboptimal scheduling.
Innovation Solution
A list scheduler dynamically selects from multiple alternative instruction sequences by performing a cost analysis and look-ahead strategy, considering machine resources like dependency depth and register pressure, to optimize instruction scheduling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If instruction sequence selection is performed prior to scheduling, then the selection process is simplified, but it is not possible to determine the optimal instruction sequence for given program conditions
Solution Approach 1:
The patent implements dynamic instruction sequence selection during the scheduling phase rather than statically before scheduling. The list scheduler evaluates multiple alternative instruction sequences and selects the optimal one based on current resource availability and program state, making the selection adaptive to changing conditions while maintaining scheduling efficiency
Solution Approach 2:
The patent performs preliminary identification and tracking of alternative instruction sequences before scheduling begins. By pre-processing and organizing alternative sequences in an available instruction list with associated cost metrics, the system prepares multiple options in advance that can be efficiently evaluated during scheduling without compromising optimality
2Adaptability or versatility
If alternative instruction sequences utilize different hardware resources, then flexibility in resource allocation increases, but it becomes difficult to select the optimal instruction sequence due to varying machine resource requirements
Solution Approach 1:
The patent implements feedback mechanisms where the list scheduler continuously monitors current resource utilization and adjusts instruction sequence selection accordingly. Cost metrics are dynamically updated based on actual resource state, allowing the scheduler to select sequences that optimize resource usage at each scheduling decision point
Solution Approach 2:
The patent changes the parameters used for instruction sequence selection from static to dynamic values. Instead of fixed selection criteria, the system uses variable cost metrics that reflect current resource availability, dependency depth, and register pressure, enabling adaptive optimization as program execution progresses
Data Source
AI summary
A list scheduler in a compiler can select from a plurality of alternative instruction sequences for one or more computation performed within an application. A scheduler can initially identify and track one or more computations for which multiple alternative instruction sequences exist. An available instruction list can be populated with the alternative instruction sequences. The list scheduler can access the available instruction list during scheduling of the application. The list scheduler can perform a cost analysis while scheduling the instructions by performing a look ahead. The list scheduler may select alternate instruction sequences for similar computations occurring in different portions of the application based on the cost benefit analysis.