func (b *Block) Fatalf(msg string, args ...interface{}) { b.Func.Fatalf(msg, args...) }

type BranchPrediction int8

const (
	BranchUnlikely = BranchPrediction(-1)
	BranchUnknown  = BranchPrediction(0)
	BranchLikely   = BranchPrediction(+1)
)

type Hotness int8 // Could use negative numbers for specifically non-hot blocks, but don't, yet.
const (

func describePredictionAgrees(b *Block, prediction BranchPrediction) string {
	s := ""
	if prediction == b.Likely {
		s = " (agrees with previous)"
	} else if b.Likely != BranchUnknown {
		s = " (disagrees with previous, ignored)"
	}
	return s
}

func describeBranchPrediction(f *Func, b *Block, likely, not int8, prediction BranchPrediction) {
	f.Warnl(b.Pos, "Branch prediction rule %s < %s%s",

		s.stmtList(cond.Init())
		s.condBranch(cond.X, yes, no, likely)
		return
	}
	c := s.expr(cond)
	b := s.endBlock()
	b.Kind = ssa.BlockIf
	b.SetControl(c)
	b.Likely = ssa.BranchPrediction(likely) // gc and ssa both use -1/0/+1 for likeliness
	b.AddEdgeTo(yes)
	b.AddEdgeTo(no)
}

type skipMask uint8

const (
	skipPtr skipMask = 1 << iota
	skipLen
	skipCap
)