Efficient vectorization of SIMD programs with non-aligned and irregular data access hardware

Automatic vectorization of programs for partitioned-ALU SIMD (Single Instruction Multiple Data) processors has been difficult because of not only data dependency issues but also non-aligned and irregular data access problems. A nonaligned or irregular data access operation incurs many overhead cycles for data alignment. Moreover, this causes difficulty in efficient code generation and hinders automatic vectorization. In this paper, we employ special memory access hardware for improving the performance of SIMD processors; one is the split line buffer and the other is the packing buffer. The former solves the non-aligned memory access problem, while the latter simplifies irregular and stride data access. The addition of these hardware units not only requires very small changes to the instruction set architecture but also contributes to the significant performance improvement by vectorizing more loops and reducing the overhead cycles. We have also developed an auto-vectorization compiler...

• Type: Conference
• Year: 2008
• Where: CASES
• Authors: Hoseok Chang, Wonyong Sung
• Keywords: Automatic Vectorization, CASES 2008, Irregular Data Access, Split Line Buffer, System Software