go/src/cmd/compile/internal/ssa/lower.go

// convert to machine-dependent ops.
func lower(f *Func) { … }

// lateLower applies those rules that need to be run after the general lower rules.
func lateLower(f *Func) { … }

// checkLower checks for unlowered opcodes and fails if we find one.
func checkLower(f *Func) { … }