Available Expression Analysis is classified as which type of Data-Flow Analysis framework?
An expression x + y is available at point p if it was computed along ALL paths leading to p without subsequent redefinition of x or y (Forward, Must-analysis using intersection intersection).
Reaching Definitions Analysis determines:
Reaching Definitions determines which variable definitions d: x = ... can reach point p without an intervening assignment to x.
In Control Flow Graphs (CFG), node D 'Dominates' node N (written D dom N) if:
Dominance Definition: Node D dominates N if D lies on every control flow path from entry to N.
In a Control Flow Graph, a CFG edge A -> B is a 'Back Edge' if:
A back edge in CFG points from node A to an ancestor node B in the dominator tree where B dom A, forming a natural loop.
Peephole Optimization operates on:
Peephole optimization inspects a small window of 2-4 contiguous target instructions to remove redundant loads/stores, algebraic identities (x + 0), and jump chains.