Instruction combining for coalescing memory accesses using global code motion

Instruction combining is an optimization to replace a sequence of instructions with a more efficient instruction yielding the same result in a fewer machine cycles. When we use it for coalescing memory accesses, we can reduce the memory traffic by combining narrow memory references with contiguous addresses into a wider reference for taking advantage of a wide-bus architecture. Coalescing memory accesses can improve performance for two reasons: one by reducing the additional cycles required for moving data from caches to registers and the other by reducing the stall cycles caused by multiple outstanding memory access requests. Previous approaches for memory access coalescing focus only on array access instructions related to loop induction variables, and thus they miss many other opportunities. In this paper, we propose a new algorithm for instruction combining by applying global code motion to wider regions of the given program in search of more potential candidates. We implemented t...

• Type: Conference
• Year: 2004
• Where: ACMMSP
• Authors: Motohiro Kawahito, Hideaki Komatsu, Toshio Nakatani
• Keywords: Access Coalescing Focus, ACMMSP 2004, Instruction Combining, Memory Accesses