Syntax-directed divide-and-conquer data-flow analysis

Abstract

Link-time optimization, with which GCC and LLVM are equipped, generally deals with large-scale procedures because of aggressive procedure inlining. Data-flow analysis (DFA), which is an essential computation for compiler optimization, is therefore desired to deal with large-scale procedures. One promising approach to the DFA of largescale procedures is divide-and-conquer parallelization. However, DFA on control-flow graphs is difficult to divide and conquer. If we perform DFA on abstract syntax trees (ASTs) in a syntax-directed manner, the divide and conquer of DFA becomes straightforward, owing to the recursive structure of ASTs, but then nonstructural control flow such as goto/label becomes a problem. In order to resolve it, we have developed a novel syntax-directed method of DFA on ASTs that can deal with goto/label and is ready to divide-and-conquer parallelization. We tested the feasibility of our method experimentally through prototype implementations and observed that our prototype achieved a significant speedup.