blob: 8d6dce41df9508c053c062b4c5034113a66e60be [file] [log] [blame]
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package main
import (
"cmd/internal/gc"
"cmd/internal/obj"
"cmd/internal/obj/arm64"
)
func stackcopy(n, res *gc.Node, osrc, odst, w int64) {
// determine alignment.
// want to avoid unaligned access, so have to use
// smaller operations for less aligned types.
// for example moving [4]byte must use 4 MOVB not 1 MOVW.
align := int(n.Type.Align)
var op int
switch align {
default:
gc.Fatal("sgen: invalid alignment %d for %v", align, gc.Tconv(n.Type, 0))
case 1:
op = arm64.AMOVB
case 2:
op = arm64.AMOVH
case 4:
op = arm64.AMOVW
case 8:
op = arm64.AMOVD
}
if w%int64(align) != 0 {
gc.Fatal("sgen: unaligned size %d (align=%d) for %v", w, align, gc.Tconv(n.Type, 0))
}
c := int32(w / int64(align))
if osrc%int64(align) != 0 || odst%int64(align) != 0 {
gc.Fatal("sgen: unaligned offset src %d or dst %d (align %d)", osrc, odst, align)
}
// if we are copying forward on the stack and
// the src and dst overlap, then reverse direction
dir := align
if osrc < odst && int64(odst) < int64(osrc)+w {
dir = -dir
}
var dst gc.Node
var src gc.Node
if n.Ullman >= res.Ullman {
gc.Agenr(n, &dst, res) // temporarily use dst
gc.Regalloc(&src, gc.Types[gc.Tptr], nil)
gins(arm64.AMOVD, &dst, &src)
if res.Op == gc.ONAME {
gc.Gvardef(res)
}
gc.Agen(res, &dst)
} else {
if res.Op == gc.ONAME {
gc.Gvardef(res)
}
gc.Agenr(res, &dst, res)
gc.Agenr(n, &src, nil)
}
var tmp gc.Node
gc.Regalloc(&tmp, gc.Types[gc.Tptr], nil)
// set up end marker
var nend gc.Node
// move src and dest to the end of block if necessary
if dir < 0 {
if c >= 4 {
gc.Regalloc(&nend, gc.Types[gc.Tptr], nil)
gins(arm64.AMOVD, &src, &nend)
}
p := gins(arm64.AADD, nil, &src)
p.From.Type = obj.TYPE_CONST
p.From.Offset = w
p = gins(arm64.AADD, nil, &dst)
p.From.Type = obj.TYPE_CONST
p.From.Offset = w
} else {
p := gins(arm64.AADD, nil, &src)
p.From.Type = obj.TYPE_CONST
p.From.Offset = int64(-dir)
p = gins(arm64.AADD, nil, &dst)
p.From.Type = obj.TYPE_CONST
p.From.Offset = int64(-dir)
if c >= 4 {
gc.Regalloc(&nend, gc.Types[gc.Tptr], nil)
p := gins(arm64.AMOVD, &src, &nend)
p.From.Type = obj.TYPE_ADDR
p.From.Offset = w
}
}
// move
// TODO: enable duffcopy for larger copies.
if c >= 4 {
p := gins(op, &src, &tmp)
p.From.Type = obj.TYPE_MEM
p.From.Offset = int64(dir)
p.Scond = arm64.C_XPRE
ploop := p
p = gins(op, &tmp, &dst)
p.To.Type = obj.TYPE_MEM
p.To.Offset = int64(dir)
p.Scond = arm64.C_XPRE
p = gcmp(arm64.ACMP, &src, &nend)
gc.Patch(gc.Gbranch(arm64.ABNE, nil, 0), ploop)
gc.Regfree(&nend)
} else {
// TODO(austin): Instead of generating ADD $-8,R8; ADD
// $-8,R7; n*(MOVDU 8(R8),R9; MOVDU R9,8(R7);) just
// generate the offsets directly and eliminate the
// ADDs. That will produce shorter, more
// pipeline-able code.
var p *obj.Prog
for {
tmp14 := c
c--
if tmp14 <= 0 {
break
}
p = gins(op, &src, &tmp)
p.From.Type = obj.TYPE_MEM
p.From.Offset = int64(dir)
p.Scond = arm64.C_XPRE
p = gins(op, &tmp, &dst)
p.To.Type = obj.TYPE_MEM
p.To.Offset = int64(dir)
p.Scond = arm64.C_XPRE
}
}
gc.Regfree(&dst)
gc.Regfree(&src)
gc.Regfree(&tmp)
}