Module regalloc 

Public API for regalloc. Linear-scan register allocator.

Reference: Poletto & Sarkar, “Linear Scan Register Allocation”, TOPLAS 1999.

Algorithm:

1. Compute per-VReg live intervals by a single pass over all instructions.
2. Sort intervals by start point.
3. Scan forward: maintain an “active” set sorted by end point.
   • Expire intervals whose end ≤ current start (return their regs to free pool).
   • If a free register exists, assign it.
   • Otherwise spill the interval with the largest end point.

Re-exports

pub use crate::regalloc_gc::graph_color;

Structs

LiveInterval

Half-open live interval [start, end) in flat instruction program order.

RegAllocResult

Maps each VReg to the PReg it was assigned, or records it as spilled.

Enums

RegAllocStrategy

Register allocation strategy used by allocate_registers.

Functions

allocate_registers

Allocate registers with the selected strategy.

apply_allocation

Replace MOperand::VReg with MOperand::PReg in mf according to result. Also rewrites instr.dst so that the destination register number reflects the assigned physical register rather than the raw VReg counter. Spilled VRegs are left unchanged (the caller must handle them).

compute_live_intervals

Build live intervals by scanning all instructions of mf.

insert_spill_reloads

Insert spill stores and reload loads for all spilled VRegs.

linear_scan

Run linear-scan allocation over intervals using allocatable registers.