Emulator Register Optimization for Instruction Stream Translation

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Solution Overview

Problem

Conventional emulation methods face inefficiencies in translating instruction streams from one computing environment to another, despite existing techniques like hardware/software schemes, SimOS, SimICS, and code optimization methods, as they do not uniformly achieve optimal performance across all systems.

Innovation Solution

The method involves tracking frequently executed instruction sequences, optimizing register-based instructions by converting them into immediate form, and associating assumption tests to ensure efficient execution on the host system, while discarding translations for infrequently accessed memory pages to enhance emulation efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional emulation translation methods are used, then instruction streams can be executed on different architectures, but emulation efficiency and performance are suboptimal

Engineering Contradiction:
Improveemulation efficiencyVSAvoidtranslation overhead
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The patent combines interpretation and translation into a unified emulation process, where the emulator both interprets target instructions and translates them to host instructions. This integration allows the system to leverage both approaches: interpretation for flexibility and translation for performance optimization, thereby improving overall emulation efficiency while reducing translation overhead through intelligent selection of execution modes.

Inventive Principle:
Principle #5Merging (Combining)

2Productivity

If aggressive optimization techniques are applied during translation, then code execution performance improves, but the complexity of the translation process increases

Engineering Contradiction:
Improvecode execution performanceVSAvoidtranslation process complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent performs preliminary analysis of target instruction sequences to identify frequently executed code paths before applying optimization techniques. By pre-identifying hot spots and analyzing instruction patterns in advance, the emulator can apply aggressive optimizations only where beneficial, rather than uniformly across all code. This preliminary action reduces the complexity burden by focusing translation efforts on critical paths.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent applies different optimization strategies to different regions of the translated code based on their execution characteristics. Frequently executed instruction sequences receive aggressive optimizations including register allocation and instruction reordering, while less critical code paths use simpler translation approaches. This localized application of optimization techniques improves overall code execution performance without uniformly increasing translation process complexity.

Inventive Principle:
Principle #3Local quality

3Speed

If all instruction sequences are translated, then execution speed improves, but memory usage and translation overhead increase

Engineering Contradiction:
Improveexecution speedVSAvoidmemory usage
Core Design Contradiction:
SpeedVSQuantity of substance

Solution Approach 1:

The patent implements partial translation by selectively translating only the most frequently executed instruction sequences to host instructions, while leaving less critical code to be executed through interpretation. This partial approach to translation improves execution speed for hot paths without incurring the memory usage and translation overhead that would result from translating all instruction sequences. The emulator dynamically determines which code regions warrant translation based on execution frequency analysis.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP2082318B1Register-based instruction optimization for facilitating efficient emulation of an instruction stream
Publication Date: 2013.02.27 INTERNATIONAL BUSINESS MACHINE CORPORATION
  • EP2082318B1 patent drawingFigure 1
  • EP2082318B1 patent drawingFigure 2A
  • EP2082318B1 patent drawingFigure 2B

AI summary

A register-based instruction optimization is provided for facilitating efficient emulation of a target instruction stream. The optimization includes for at least one instruction in a frequently executed sequence of target instructions: confirming that at least one register is marked as a read-only register for the sequence; confirming that each register of the at least one register has been detected to have a constant value for the at least one instruction in multiple prior iterations of the executed sequence; and response thereto, optimizing the at least one instruction by replacing the at least one instruction with at least one immediate form instruction having at least one constant value encoded directly therein from the at least one register. The optimization results in an optimized sequence of target instructions, which when translated into a sequence of host instructions, is more efficiently executed by a host computing environment.