// attempt to preserve statement marker.
		b.Pos = b.Pos.WithIsStmt()
	}
	if branch == positive || branch == negative {
		b.Kind = BlockFirst
		b.ResetControls()
		if branch == positive {
			b.swapSuccessors()
		}
	} else {
		// TODO: figure out how to remove an entry from a jump table
	}
}

// isNonNegative reports whether v is known to be greater or equal to zero.