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// Copyright 2016 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 riscv64
import (
"cmd/compile/internal/gc"
"cmd/internal/obj"
"cmd/internal/obj/riscv"
)
func zeroRange(pp *gc.Progs, p *obj.Prog, off, cnt int64, _ *uint32) *obj.Prog {
if cnt == 0 {
return p
}
// Adjust the frame to account for LR.
off += gc.Ctxt.FixedFrameSize()
if cnt < int64(4*gc.Widthptr) {
for i := int64(0); i < cnt; i += int64(gc.Widthptr) {
p = pp.Appendpp(p, riscv.AMOV, obj.TYPE_REG, riscv.REG_ZERO, 0, obj.TYPE_MEM, riscv.REG_SP, off+i)
}
return p
}
if cnt <= int64(128*gc.Widthptr) {
p = pp.Appendpp(p, riscv.AADDI, obj.TYPE_CONST, 0, off, obj.TYPE_REG, riscv.REG_A0, 0)
p.Reg = riscv.REG_SP
p = pp.Appendpp(p, obj.ADUFFZERO, obj.TYPE_NONE, 0, 0, obj.TYPE_MEM, 0, 0)
p.To.Name = obj.NAME_EXTERN
p.To.Sym = gc.Duffzero
p.To.Offset = 8 * (128 - cnt/int64(gc.Widthptr))
return p
}
// Loop, zeroing pointer width bytes at a time.
// ADD $(off), SP, T0
// ADD $(cnt), T0, T1
// loop:
// MOV ZERO, (T0)
// ADD $Widthptr, T0
// BNE T0, T1, loop
p = pp.Appendpp(p, riscv.AADD, obj.TYPE_CONST, 0, off, obj.TYPE_REG, riscv.REG_T0, 0)
p.Reg = riscv.REG_SP
p = pp.Appendpp(p, riscv.AADD, obj.TYPE_CONST, 0, cnt, obj.TYPE_REG, riscv.REG_T1, 0)
p.Reg = riscv.REG_T0
p = pp.Appendpp(p, riscv.AMOV, obj.TYPE_REG, riscv.REG_ZERO, 0, obj.TYPE_MEM, riscv.REG_T0, 0)
loop := p
p = pp.Appendpp(p, riscv.AADD, obj.TYPE_CONST, 0, int64(gc.Widthptr), obj.TYPE_REG, riscv.REG_T0, 0)
p = pp.Appendpp(p, riscv.ABNE, obj.TYPE_REG, riscv.REG_T0, 0, obj.TYPE_BRANCH, 0, 0)
p.Reg = riscv.REG_T1
gc.Patch(p, loop)
return p
}
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