Compiler Metadata for Binary Emulation Optimization

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Solution Overview

Problem

Debugging software applications is inefficient due to the high overhead of bit-accurate tracing in production environments, which limits the practicality of recording and replaying execution traces of machine code instructions.

Innovation Solution

The use of compiler-generated emulation optimization metadata to reduce the number of steps needed to emulate machine code instructions, while preserving externally visible side-effects, by leveraging higher-level program behaviors expressed in source code, such as memory ordering constraints and volatility, to optimize binary emulation and trace recording.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If binary emulation is used to record bit-accurate traces, then tracing accuracy is improved, but emulation overhead increases

Engineering Contradiction:
Improvetracing accuracyVSAvoidemulation overhead
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The compiler performs preliminary analysis of source code during the compilation phase to generate metadata that captures high-level program behaviors, memory ordering constraints, and volatility information. This preliminary action allows the emulator to skip detailed tracing of certain operations and directly reproduce their effects, significantly reducing emulation overhead while maintaining bit-accurate tracing accuracy for critical operations.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent introduces compiler-generated metadata as an intermediary between the source code and the emulator. This metadata serves as a bridge that translates high-level source code semantics into optimization hints for the emulator, allowing it to make informed decisions about which operations require detailed tracing and which can be optimized or skipped, thereby reducing overall emulation overhead.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If full bit-accurate tracing is performed during binary emulation, then trace accuracy is improved, but trace file size increases

Engineering Contradiction:
Improvetrace accuracyVSAvoidtrace file size
Core Design Contradiction:
Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent extracts and records only the essential trace information needed for accurate replay, using compiler metadata to identify which operations require detailed tracing. By taking out only the critical trace data rather than recording all operations, the system maintains trace accuracy while significantly reducing the quantity of trace information stored, thus decreasing trace file size.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The system changes the parameters of trace recording by using compiler-generated metadata to dynamically determine which operations should be traced with full detail and which can use summarized or skipped recording. This parameter-based approach allows flexible adjustment of trace granularity, maintaining accuracy for critical operations while reducing overall trace file size through selective recording.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If compiler metadata is used to optimize emulation, then emulation speed is improved, but compilation complexity increases

Engineering Contradiction:
Improveemulation speedVSAvoidcompilation complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The compiler performs self-service by automatically analyzing source code during compilation and generating the necessary metadata without requiring external intervention. This self-service approach captures program behaviors, memory ordering constraints, and volatility information, storing them in the compiled binary. The emulator then uses this pre-generated metadata to optimize execution speed, while the compilation complexity increase is confined to the compilation phase only.

Inventive Principle:
Principle #25Self-service

4Measurement precision

If detailed tracing of all machine code instructions is performed, then debugging precision is improved, but debugging time increases

Engineering Contradiction:
Improvedebugging precisionVSAvoiddebugging time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The compiler performs preliminary analysis of source code to generate metadata that identifies critical operations requiring detailed tracing. This preliminary action allows the emulator to focus tracing efforts on only those operations that impact program behavior, maintaining debugging precision while avoiding unnecessary detailed tracing of redundant operations, thus reducing overall debugging time.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

Instead of performing detailed tracing on all machine code instructions (excessive action), the system uses compiler metadata to apply partial tracing only to critical operations that affect program behavior. This partial action approach maintains sufficient debugging precision for identifying bugs while significantly reducing the time spent tracing irrelevant operations.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP3895022B1Improving emulation and tracing performance using compiler-generated emulation optimization metadata
Publication Date: 2022.11.02 MICROSOFT TECHNOLOGY LICENSING LLC
  • EP3895022B1 patent drawingFigure 1
  • EP3895022B1 patent drawingFigure 2
  • EP3895022B1 patent drawingFigure 3

AI summary

An emulator can use compiler metadata to efficiently emulate execution of executable machine code compiled from the source code. Based on accessing compiler metadata associated with machine code, an emulator can identify behavior(s) of the source code from which the machine code is compiled which are not implied by the machine code. From these behaviors, the emulator can identify emulator optimization(s) that can be applied, during emulation of execution of a thread, to reduce a number of steps needed to emulate execution the machine code, while preserving any externally-visible side-effects. These optimizations can operate to reduce a number of emulator operations needed emulate execution of the machine code, or to elide one or more machine code instructions from emulation. These optimizations can then be applied while emulating execution of the thread. The emulated execution could be recorded to a trace that is equivalent to a trace recorded without these optimizations.