ggen.go

     1  // Copyright 2009 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package amd64
     6  
     7  import (
     8  	"cmd/compile/internal/objw"
     9  	"cmd/internal/obj"
    10  	"cmd/internal/obj/x86"
    11  )
    12  
    13  func zerorange(pp *objw.Progs, p *obj.Prog, off, cnt int64, state *uint32) *obj.Prog {
    14  	if cnt%8 != 0 {
    15  		panic("zeroed region not aligned")
    16  	}
    17  	for cnt >= 16 {
    18  		p = pp.Append(p, x86.AMOVUPS, obj.TYPE_REG, x86.REG_X15, 0, obj.TYPE_MEM, x86.REG_SP, off)
    19  		off += 16
    20  		cnt -= 16
    21  	}
    22  	if cnt != 0 {
    23  		p = pp.Append(p, x86.AMOVQ, obj.TYPE_REG, x86.REG_X15, 0, obj.TYPE_MEM, x86.REG_SP, off)
    24  	}
    25  	return p
    26  }
    27  
    28  func ginsnop(pp *objw.Progs) *obj.Prog {
    29  	// This is a hardware nop (1-byte 0x90) instruction,
    30  	// even though we describe it as an explicit XCHGL here.
    31  	// Particularly, this does not zero the high 32 bits
    32  	// like typical *L opcodes.
    33  	// (gas assembles "xchg %eax,%eax" to 0x87 0xc0, which
    34  	// does zero the high 32 bits.)
    35  	p := pp.Prog(x86.AXCHGL)
    36  	p.From.Type = obj.TYPE_REG
    37  	p.From.Reg = x86.REG_AX
    38  	p.To.Type = obj.TYPE_REG
    39  	p.To.Reg = x86.REG_AX
    40  	return p
    41  }
    42
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