Lexicon Entry

PHI Node

An SSA construct that selects a value based on which predecessor basic block control flow came from. Necessary because in SSA form each variable has exactly one definition.

Related Knowledge & Cross-References

Guide

Apr 3, 2026

LLVM IR Tutorial: The Hidden Language Between Your C Code and Assembly

Master LLVM IR in this hands-on tutorial. Learn SSA form, basic blocks, and PHI nodes with real Clang output and Godbolt examples — from C to IR to x86-64 and ARM64.