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register spilling

Keeping a value in a stack slot because no register is free for it, storing it there and loading it back when it is needed.

Spilling assigns a value's live range (or part of it) to a stack slot, inserting a store after its definition and loads before its uses; the inserted instructions are spill code.

Examples

  • With more live values than registers, the compiler stores one at [rsp + 8] and loads it back when it is needed.

See also

stack slot live range register pressure register allocation
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