/* * register dr is one of the special ones (AX, CX, DI, SI, etc.). * we need to use it. if it is already allocated as a temporary * (r > 1; can only happen if a routine like sgen passed a * special as cgen's res and then cgen used regalloc to reuse * it as its own temporary), then move it for now to another * register. caller must call restx to move it back. * the move is not necessary if dr == res, because res is * known to be dead. */ func savex(dr int, x *gc.Node, oldx *gc.Node, res *gc.Node, t *gc.Type) { r := reg[dr] // save current ax and dx if they are live // and not the destination *oldx = gc.Node{} gc.Nodreg(x, t, dr) if r > 1 && !gc.Samereg(x, res) { gc.Regalloc(oldx, gc.Types[gc.TINT64], nil) x.Type = gc.Types[gc.TINT64] gmove(x, oldx) x.Type = t oldx.Etype = r // squirrel away old r value reg[dr] = 1 } }