Instruction Code Selection

• Published in: SSA-based Compiler Design pp. 257 - 268
• Main Authors: Ebner, Dietmar, Krall, Andreas, Scholz, Bernhard
• Format: Book Chapter
• Language: English
• Published: Cham Springer International Publishing 2022
• Subjects: Code generation; Code selection; Compiler back-end; Compiler design; Data-flow tree; Def-use chain; Instruction selection; Multiple output instructions; Non-terminal symbol; Partitioned Boolean quadratic problem (PBQP); Pattern matching; SSA graph; Static single assignment form (SSA form); Terminal symbol
• ISBN: 303080514X; 9783030805142
• DOI: 10.1007/978-3-030-80515-9_19

In this chapter, we introduce how SSA form can be used for instruction selection. Instruction selection translates a machine-independent intermediate code representation into a low-level intermediate representation or into machine code. Classical techniques specialize for specific target architectures and limit the scope to statement level. In this chapter, we present an optimal technique for intra-procedural instruction selection that uses partitioned Boolean quadratic optimization. The presented approach goes beyond limitations such as instruction selection expressed as trees and permits complex acyclic graph patterns in order to find the most suitable complex instructions in an instruction set. Such instructions can have multiple inputs and results at the same time.