A love letter to liveness analysis: from SSA to registers
An ode to livelyness analysis; SSA to registers
The author walks through liveness analysis for register allocation in purple-garden, a language whose SSA IR uses block parameters instead of phi nodes. He shows how to compute each virtual register's live range by walking blocks in reverse, observing uses and definitions, then feeds those ranges into a linear-scan register allocator for both a bytecode VM and an x86 JIT. The post includes Rust implementations of the core observation and helper functions.
Register allocation is assigning the unlimited amount of virtual registers to the limited set of storage resources hardware has, specifically the general purpose registers, the floating point registers and the stack.