path: root/vendor/github.com/google/gops/internal/obj/arm64/obj7.go

// cmd/7l/noop.c, cmd/7l/obj.c, cmd/ld/pass.c from Vita Nuova.
// https://code.google.com/p/ken-cc/source/browse/
//
// 	Copyright © 1994-1999 Lucent Technologies Inc. All rights reserved.
// 	Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
// 	Portions Copyright © 1997-1999 Vita Nuova Limited
// 	Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
// 	Portions Copyright © 2004,2006 Bruce Ellis
// 	Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
// 	Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
// 	Portions Copyright © 2009 The Go Authors. All rights reserved.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

package arm64

import (
	"fmt"
	"log"
	"math"

	"github.com/google/gops/internal/obj"
	"github.com/google/gops/internal/sys"
)

var complements = []obj.As{
	AADD:  ASUB,
	AADDW: ASUBW,
	ASUB:  AADD,
	ASUBW: AADDW,
	ACMP:  ACMN,
	ACMPW: ACMNW,
	ACMN:  ACMP,
	ACMNW: ACMPW,
}

func stacksplit(ctxt *obj.Link, p *obj.Prog, framesize int32) *obj.Prog {
	// MOV	g_stackguard(g), R1
	p = obj.Appendp(ctxt, p)

	p.As = AMOVD
	p.From.Type = obj.TYPE_MEM
	p.From.Reg = REGG
	p.From.Offset = 2 * int64(ctxt.Arch.PtrSize) // G.stackguard0
	if ctxt.Cursym.CFunc() {
		p.From.Offset = 3 * int64(ctxt.Arch.PtrSize) // G.stackguard1
	}
	p.To.Type = obj.TYPE_REG
	p.To.Reg = REG_R1

	q := (*obj.Prog)(nil)
	if framesize <= obj.StackSmall {
		// small stack: SP < stackguard
		//	MOV	SP, R2
		//	CMP	stackguard, R2
		p = obj.Appendp(ctxt, p)

		p.As = AMOVD
		p.From.Type = obj.TYPE_REG
		p.From.Reg = REGSP
		p.To.Type = obj.TYPE_REG
		p.To.Reg = REG_R2

		p = obj.Appendp(ctxt, p)
		p.As = ACMP
		p.From.Type = obj.TYPE_REG
		p.From.Reg = REG_R1
		p.Reg = REG_R2
	} else if framesize <= obj.StackBig {
		// large stack: SP-framesize < stackguard-StackSmall
		//	SUB	$framesize, SP, R2
		//	CMP	stackguard, R2
		p = obj.Appendp(ctxt, p)

		p.As = ASUB
		p.From.Type = obj.TYPE_CONST
		p.From.Offset = int64(framesize)
		p.Reg = REGSP
		p.To.Type = obj.TYPE_REG
		p.To.Reg = REG_R2

		p = obj.Appendp(ctxt, p)
		p.As = ACMP
		p.From.Type = obj.TYPE_REG
		p.From.Reg = REG_R1
		p.Reg = REG_R2
	} else {
		// Such a large stack we need to protect against wraparound
		// if SP is close to zero.
		//	SP-stackguard+StackGuard < framesize + (StackGuard-StackSmall)
		// The +StackGuard on both sides is required to keep the left side positive:
		// SP is allowed to be slightly below stackguard. See stack.h.
		//	CMP	$StackPreempt, R1
		//	BEQ	label_of_call_to_morestack
		//	ADD	$StackGuard, SP, R2
		//	SUB	R1, R2
		//	MOV	$(framesize+(StackGuard-StackSmall)), R3
		//	CMP	R3, R2
		p = obj.Appendp(ctxt, p)

		p.As = ACMP
		p.From.Type = obj.TYPE_CONST
		p.From.Offset = obj.StackPreempt
		p.Reg = REG_R1

		p = obj.Appendp(ctxt, p)
		q = p
		p.As = ABEQ
		p.To.Type = obj.TYPE_BRANCH

		p = obj.Appendp(ctxt, p)
		p.As = AADD
		p.From.Type = obj.TYPE_CONST
		p.From.Offset = obj.StackGuard
		p.Reg = REGSP