What Is Static Single Assignment?
Static single assignment, or SSA, is a compiler intermediate representation in which every variable is assigned exactly one time, with new versioned names created for each reassignment. Where control flow merges, special phi nodes select which version reaches that point. This single-definition property makes data dependencies explicit and easy to track.
Why it matters
SSA form makes many optimizations simpler and faster because each value has a single, unambiguous definition to follow. It underlies passes like constant propagation and dead code elimination in modern compilers.
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