Date of Award

3-2014

Degree Name

MS in Electrical Engineering

Department

Electrical Engineering

Advisor

Chris Lupo

Abstract

It is important for compilers to generate executable code that is as small as possible, particularly when generating code for embedded systems. One method of reducing code size is to use instruction set architectures (ISAs) that support combining multiple operations into single operations. The ARM ISA allows for combining multiple memory operations to contiguous memory addresses into a single operation. The LLVM compiler contains a specific memory optimization to perform this combining of memory operations, called ARMLoadStoreOpt. This optimization, however, relies on another optimization (ARMPreAllocLoadStoreOpt) to move eligible memory operations into proximity in order to perform properly. This mover optimization occurs before register allocation, while ARMLoadStoreOpt occurs after register allocation. This thesis implements a similar mover optimization (called MagnetPass) after register allocation is performed, and compares this implementation with the existing optimization. While in most cases the two optimizations provide comparable results, our implementation in its current state requires some improvements before it will be a viable alternative to the existing optimization. Specifically, the algorithm will need to be modified to reduce computational complexity, and our implementation will need to take care not to interfere with other LLVM optimizations.

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