The Effect of Program Optimization on Trace Cache Efficiency

Trace cache, an instruction fetch technique that reduces taken branch penalties by storing and fetching program instructions in dynamic execution order, dramatically improves instruction fetch bandwidth. Similarly, program transformations like loop unrolling, procedure inlining, feedback-directed program restructuring, and profiledirected feedback can improve instruction fetch bandwidth by changing the static structure and ordering of a program's basic blocks. We examine the interaction of these compiletime and run-time techniques in the context of a high-quality production compiler that implements such transformations and a cycle-accurate simulation model of a wide issue superscalar processor. Not surprisingly, we find that the relative benefit of adding trace cache declines with increasing optimization level, and vice versa. Furthermore, we find that certain optimizations that improve performance on a processor model without trace cache can actually degrade performance on a pro...

• Type: Conference
• Year: 1999
• Where: IEEEPACT
• Authors: Derek L. Howard, Mikko H. Lipasti
• Keywords: Distributed And Parallel Computing, IEEEPACT 1999, Instruction Fetch Bandwidth, Instruction Fetch Technique, Trace Cache