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insert_spill_reloads

llvm_codegen::regalloc

Function insert_spill_reloads 

Source 
pub fn insert_spill_reloads(
    mf: &mut MachineFunction,
    result: &mut RegAllocResult,
    load_op: MOpcode,
    store_op: MOpcode,
)
Expand description

Insert spill stores and reload loads for all spilled VRegs.

For each spilled VReg v:

  • After every instruction that defines v, insert a STORE of v to its frame slot using a fresh VReg.
  • Before every instruction that uses v, insert a LOAD from its frame slot into a fresh VReg, and replace the use with that fresh VReg.

Fresh VRegs are then allocated in a second linear-scan pass (they have very short live intervals so they virtually never cause additional spills). The result is merged into result.

load_op / store_op are target-provided opcodes. The instructions have the layout:

  • LOAD: dst = VReg(fresh), operands = [Imm(slot)]
  • STORE: dst = None, operands = [Imm(slot), VReg(src)]