Struct LinearScanAllocator 

pub struct LinearScanAllocator;

Classic linear scan register allocator (Poletto & Sarkar, 1999).

Usage:

let intervals = LinearScanAllocator::compute_intervals(&function);
let free_regs = vec!["r12", "r13", "r14", "r15", "rbx"];
let alloc_map = LinearScanAllocator::allocate(&intervals, &free_regs);

Implementations

impl LinearScanAllocator

pub fn compute_intervals(function: &Function) -> Vec<LiveInterval>

Compute interval hulls from instruction operands and control-flow liveness.

Positions are handed out by walking function.blocks in storage order and counting instructions. Backends compare start and end against positions they number the same way — the clobber ranges that keep a value out of a caller-saved register across a call are built like this — so the two numberings are one index space and changing the order here without changing every backend that shares it silently assigns a live value to a clobbered register.

pub fn allocate<R: Copy + Eq>( intervals: &[LiveInterval], available_regs: &[R], ) -> HashMap<VirtualReg, Allocation<R>>

Run the linear scan allocation algorithm.

intervals must be sorted by start (as returned by compute_intervals). available_regs is the pool of physical registers to draw from (any Copy + Eq type works — for x86_64 pass &["r12", "r13", ...]).

Returns a map from each VirtualReg to either a physical register or a spill slot (negative byte offset from frame base).

pub fn allocate_with_constraints<R: Copy + Eq>( intervals: &[LiveInterval], available_regs: &[R], allowed: impl Fn(&LiveInterval, R) -> bool, ) -> HashMap<VirtualReg, Allocation<R>>

Allocate registers permitted by each interval’s target constraints.