if opcodeTable[v.Op].zeroWidth {
				if prologComplete && mustBeFirst(v) {
					panic(fmt.Errorf("Unexpected placement of op '%s' appearing after non-pseudo-op at beginning of block %s in %s\n%s", v.LongString(), b, b.Func.Name, b.Func))
				}
				if changed {
					if mustBeFirst(v) || v.Op == OpArg {
						// already taken care of above
						continue
					}

			if v.Op == OpInvalid {
				continue
			}
			b.Values[i] = v
			i++
		}
		b.Values = b.Values[:i]
	}
}

func (s *regAllocState) placeSpills() {
	mustBeFirst := func(op Op) bool {
		return op.isLoweredGetClosurePtr() || op == OpPhi || op == OpArgIntReg || op == OpArgFloatReg
	}

	// Start maps block IDs to the list of spills