Add gops agentv0.10.2-dev

1 files changed, 1029 insertions, 0 deletions

diff --git a/vendor/github.com/google/gops/internal/obj/s390x/objz.go b/vendor/github.com/google/gops/internal/obj/s390x/objz.go
new file mode 100644
index 00000000..bbf4c35c
--- /dev/null
+++ b/vendor/github.com/google/gops/internal/obj/s390x/objz.go
@@ -0,0 +1,1029 @@
+// Based on cmd/internal/obj/ppc64/obj9.go.
+//
+//	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 © 2000-2008 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 © 2000-2008 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 s390x
+
+import (
+	"fmt"
+	"math"
+
+	"github.com/google/gops/internal/obj"
+	"github.com/google/gops/internal/sys"
+)
+
+func progedit(ctxt *obj.Link, p *obj.Prog) {
+	p.From.Class = 0
+	p.To.Class = 0
+
+	// Rewrite BR/BL to symbol as TYPE_BRANCH.
+	switch p.As {
+	case ABR,
+		ABL,
+		obj.ARET,
+		obj.ADUFFZERO,
+		obj.ADUFFCOPY:
+		if p.To.Sym != nil {
+			p.To.Type = obj.TYPE_BRANCH
+		}
+	}
+
+	// Rewrite float constants to values stored in memory unless they are +0.
+	switch p.As {
+	case AFMOVS:
+		if p.From.Type == obj.TYPE_FCONST {
+			f32 := float32(p.From.Val.(float64))
+			i32 := math.Float32bits(f32)
+			if i32 == 0 { // +0
+				break
+			}
+			literal := fmt.Sprintf("$f32.%08x", i32)
+			s := obj.Linklookup(ctxt, literal, 0)
+			s.Size = 4
+			p.From.Type = obj.TYPE_MEM
+			p.From.Sym = s
+			p.From.Sym.Set(obj.AttrLocal, true)
+			p.From.Name = obj.NAME_EXTERN
+			p.From.Offset = 0
+		}
+
+	case AFMOVD:
+		if p.From.Type == obj.TYPE_FCONST {
+			i64 := math.Float64bits(p.From.Val.(float64))
+			if i64 == 0 { // +0
+				break
+			}
+			literal := fmt.Sprintf("$f64.%016x", i64)
+			s := obj.Linklookup(ctxt, literal, 0)
+			s.Size = 8
+			p.From.Type = obj.TYPE_MEM
+			p.From.Sym = s
+			p.From.Sym.Set(obj.AttrLocal, true)
+			p.From.Name = obj.NAME_EXTERN
+			p.From.Offset = 0
+		}
+
+		// put constants not loadable by LOAD IMMEDIATE into memory
+	case AMOVD:
+		if p.From.Type == obj.TYPE_CONST {
+			val := p.From.Offset
+			if int64(int32(val)) != val &&
+				int64(uint32(val)) != val &&
+				int64(uint64(val)&(0xffffffff<<32)) != val {
+				literal := fmt.Sprintf("$i64.%016x", uint64(p.From.Offset))
+				s := obj.Linklookup(ctxt, literal, 0)
+				s.Size = 8
+				p.From.Type = obj.TYPE_MEM
+				p.From.Sym = s
+				p.From.Sym.Set(obj.AttrLocal, true)
+				p.From.Name = obj.NAME_EXTERN
+				p.From.Offset = 0
+			}
+		}
+	}
+
+	// Rewrite SUB constants into ADD.
+	switch p.As {
+	case ASUBC:
+		if p.From.Type == obj.TYPE_CONST && isint32(-p.From.Offset) {
+			p.From.Offset = -p.From.Offset
+			p.As = AADDC
+		}
+
+	case ASUB:
+		if p.From.Type == obj.TYPE_CONST && isint32(-p.From.Offset) {
+			p.From.Offset = -p.From.Offset
+			p.As = AADD
+		}
+	}
+
+	if ctxt.Flag_dynlink {
+		rewriteToUseGot(ctxt, p)
+	}
+}
+
+// Rewrite p, if necessary, to access global data via the global offset table.
+func rewriteToUseGot(ctxt *obj.Link, p *obj.Prog) {
+	// At the moment EXRL instructions are not emitted by the compiler and only reference local symbols in
+	// assembly code.
+	if p.As == AEXRL {
+		return
+	}
+
+	// We only care about global data: NAME_EXTERN means a global
+	// symbol in the Go sense, and p.Sym.Local is true for a few
+	// internally defined symbols.
+	if p.From.Type == obj.TYPE_ADDR && p.From.Name == obj.NAME_EXTERN && !p.From.Sym.Local() {
+		// MOVD $sym, Rx becomes MOVD sym@GOT, Rx
+		// MOVD $sym+<off>, Rx becomes MOVD sym@GOT, Rx; ADD <off>, Rx
+		if p.To.Type != obj.TYPE_REG || p.As != AMOVD {
+			ctxt.Diag("do not know how to handle LEA-type insn to non-register in %v with -dynlink", p)
+		}
+		p.From.Type = obj.TYPE_MEM
+		p.From.Name = obj.NAME_GOTREF
+		q := p
+		if p.From.Offset != 0 {
+			q = obj.Appendp(ctxt, p)
+			q.As = AADD
+			q.From.Type = obj.TYPE_CONST
+			q.From.Offset = p.From.Offset
+			q.To = p.To
+			p.From.Offset = 0
+		}
+	}
+	if p.From3 != nil && p.From3.Name == obj.NAME_EXTERN {
+		ctxt.Diag("don't know how to handle %v with -dynlink", p)
+	}
+	var source *obj.Addr
+	// MOVD sym, Ry becomes MOVD sym@GOT, REGTMP; MOVD (REGTMP), Ry
+	// MOVD Ry, sym becomes MOVD sym@GOT, REGTMP; MOVD Ry, (REGTMP)
+	// An addition may be inserted between the two MOVs if there is an offset.
+	if p.From.Name == obj.NAME_EXTERN && !p.From.Sym.Local() {
+		if p.To.Name == obj.NAME_EXTERN && !p.To.Sym.Local() {
+			ctxt.Diag("cannot handle NAME_EXTERN on both sides in %v with -dynlink", p)
+		}
+		source = &p.From
+	} else if p.To.Name == obj.NAME_EXTERN && !p.To.Sym.Local() {
+		source = &p.To
+	} else {
+		return
+	}
+	if p.As == obj.ATEXT || p.As == obj.AFUNCDATA || p.As == obj.ACALL || p.As == obj.ARET || p.As == obj.AJMP {
+		return
+	}
+	if source.Sym.Type == obj.STLSBSS {
+		return
+	}
+	if source.Type != obj.TYPE_MEM {
+		ctxt.Diag("don't know how to handle %v with -dynlink", p)
+	}
+	p1 := obj.Appendp(ctxt, p)
+	p2 := obj.Appendp(ctxt, p1)
+
+	p1.As = AMOVD
+	p1.From.Type = obj.TYPE_MEM
+	p1.From.Sym = source.Sym
+	p1.From.Name = obj.NAME_GOTREF
+	p1.To.Type = obj.TYPE_REG
+	p1.To.Reg = REGTMP
+
+	p2.As = p.As
+	p2.From = p.From
+	p2.To = p.To
+	if p.From.Name == obj.NAME_EXTERN {
+		p2.From.Reg = REGTMP
+		p2.From.Name = obj.NAME_NONE
+		p2.From.Sym = nil
+	} else if p.To.Name == obj.NAME_EXTERN {
+		p2.To.Reg = REGTMP
+		p2.To.Name = obj.NAME_NONE
+		p2.To.Sym = nil
+	} else {
+		return
+	}
+	obj.Nopout(p)
+}
+
+func preprocess(ctxt *obj.Link, cursym *obj.LSym) {
+	// TODO(minux): add morestack short-cuts with small fixed frame-size.
+	ctxt.Cursym = cursym
+
+	if cursym.Text == nil || cursym.Text.Link == nil {
+		return
+	}
+
+	p := cursym.Text
+	textstksiz := p.To.Offset
+	if textstksiz == -8 {
+		// Compatibility hack.
+		p.From3.Offset |= obj.NOFRAME
+		textstksiz = 0
+	}
+	if textstksiz%8 != 0 {
+		ctxt.Diag("frame size %d not a multiple of 8", textstksiz)
+	}
+	if p.From3.Offset&obj.NOFRAME != 0 {
+		if textstksiz != 0 {
+			ctxt.Diag("NOFRAME functions must have a frame size of 0, not %d", textstksiz)
+		}
+	}
+
+	cursym.Args = p.To.Val.(int32)
+	cursym.Locals = int32(textstksiz)
+
+	/*
+	 * find leaf subroutines
+	 * strip NOPs
+	 * expand RET
+	 * expand BECOME pseudo
+	 */
+	if ctxt.Debugvlog != 0 {
+		ctxt.Logf("%5.2f noops\n", obj.Cputime())
+	}
+
+	var q *obj.Prog
+	var q1 *obj.Prog
+	for p := cursym.Text; p != nil; p = p.Link {
+		switch p.As {
+		/* too hard, just leave alone */
+		case obj.ATEXT:
+			q = p
+
+			p.Mark |= LABEL | LEAF | SYNC
+			if p.Link != nil {
+				p.Link.Mark |= LABEL
+			}
+
+		case ASYNC,
+			AWORD:
+			q = p
+			p.Mark |= LABEL | SYNC
+			continue
+
+		case AMOVW, AMOVWZ, AMOVD:
+			q = p
+			if p.From.Reg >= REG_RESERVED || p.To.Reg >= REG_RESERVED {
+				p.Mark |= LABEL | SYNC
+			}
+			continue
+
+		case AFABS,
+			AFADD,
+			AFDIV,
+			AFMADD,
+			AFMOVD,
+			AFMOVS,
+			AFMSUB,
+			AFMUL,
+			AFNABS,
+			AFNEG,
+			AFNMADD,
+			AFNMSUB,
+			ALEDBR,
+			ALDEBR,
+			AFSUB:
+			q = p
+
+			p.Mark |= FLOAT
+			continue
+
+		case ABL,
+			ABCL,
+			obj.ADUFFZERO,
+			obj.ADUFFCOPY:
+			cursym.Text.Mark &^= LEAF
+			fallthrough
+
+		case ABC,
+			ABEQ,
+			ABGE,
+			ABGT,
+			ABLE,
+			ABLT,
+			ABLEU,
+			ABLTU,
+			ABNE,
+			ABR,
+			ABVC,
+			ABVS,
+			ACMPBEQ,
+			ACMPBGE,
+			ACMPBGT,
+			ACMPBLE,
+			ACMPBLT,
+			ACMPBNE,
+			ACMPUBEQ,
+			ACMPUBGE,
+			ACMPUBGT,
+			ACMPUBLE,
+			ACMPUBLT,
+			ACMPUBNE:
+			p.Mark |= BRANCH
+			q = p
+			q1 = p.Pcond
+			if q1 != nil {
+				for q1.As == obj.ANOP {
+					q1 = q1.Link
+					p.Pcond = q1
+				}
+
+				if q1.Mark&LEAF == 0 {
+					q1.Mark |= LABEL
+				}
+			} else {
+				p.Mark |= LABEL
+			}
+			q1 = p.Link
+			if q1 != nil {
+				q1.Mark |= LABEL
+			}
+			continue
+
+		case AFCMPO, AFCMPU:
+			q = p
+			p.Mark |= FCMP | FLOAT
+			continue
+
+		case obj.ARET:
+			q = p
+			if p.Link != nil {
+				p.Link.Mark |= LABEL
+			}
+			continue
+
+		case obj.ANOP:
+			q1 = p.Link
+			q.Link = q1 /* q is non-nop */
+			q1.Mark |= p.Mark
+			continue
+
+		default:
+			q = p
+			continue
+		}
+	}
+
+	autosize := int32(0)
+	var p1 *obj.Prog
+	var p2 *obj.Prog
+	var pLast *obj.Prog
+	var pPre *obj.Prog
+	var pPreempt *obj.Prog
+	wasSplit := false
+	for p := cursym.Text; p != nil; p = p.Link {
+		pLast = p
+		switch p.As {
+		case obj.ATEXT:
+			autosize = int32(textstksiz)
+
+			if p.Mark&LEAF != 0 && autosize == 0 {
+				// A leaf function with no locals has no frame.
+				p.From3.Offset |= obj.NOFRAME
+			}
+
+			if p.From3.Offset&obj.NOFRAME == 0 {
+				// If there is a stack frame at all, it includes
+				// space to save the LR.
+				autosize += int32(ctxt.FixedFrameSize())
+			}
+
+			if p.Mark&LEAF != 0 && autosize < obj.StackSmall {
+				// A leaf function with a small stack can be marked
+				// NOSPLIT, avoiding a stack check.
+				p.From3.Offset |= obj.NOSPLIT
+			}
+
+			p.To.Offset = int64(autosize)
+
+			q = p
+
+			if p.From3.Offset&obj.NOSPLIT == 0 {
+				p, pPreempt = stacksplitPre(ctxt, p, autosize) // emit pre part of split check
+				pPre = p
+				wasSplit = true //need post part of split
+			}
+
+			if autosize != 0 {
+				// Make sure to save link register for non-empty frame, even if
+				// it is a leaf function, so that traceback works.
+				// Store link register before decrementing SP, so if a signal comes
+				// during the execution of the function prologue, the traceback
+				// code will not see a half-updated stack frame.
+				q = obj.Appendp(ctxt, p)
+				q.As = AMOVD
+				q.From.Type = obj.TYPE_REG
+				q.From.Reg = REG_LR
+				q.To.Type = obj.TYPE_MEM
+				q.To.Reg = REGSP
+				q.To.Offset = int64(-autosize)
+
+				q = obj.Appendp(ctxt, q)
+				q.As = AMOVD
+				q.From.Type = obj.TYPE_ADDR
+				q.From.Offset = int64(-autosize)
+				q.From.Reg = REGSP // not actually needed - REGSP is assumed if no reg is provided
+				q.To.Type = obj.TYPE_REG
+				q.To.Reg = REGSP
+				q.Spadj = autosize
+			} else if cursym.Text.Mark&LEAF == 0 {
+				// A very few functions that do not return to their caller
+				// (e.g. gogo) are not identified as leaves but still have
+				// no frame.
+				cursym.Text.Mark |= LEAF
+			}
+
+			if cursym.Text.Mark&LEAF != 0 {
+				cursym.Set(obj.AttrLeaf, true)
+				break
+			}
+
+			if cursym.Text.From3.Offset&obj.WRAPPER != 0 {
+				// if(g->panic != nil && g->panic->argp == FP) g->panic->argp = bottom-of-frame
+				//
+				//	MOVD g_panic(g), R3
+				//	CMP R3, $0
+				//	BEQ end
+				//	MOVD panic_argp(R3), R4
+				//	ADD $(autosize+8), R1, R5
+				//	CMP R4, R5
+				//	BNE end
+				//	ADD $8, R1, R6
+				//	MOVD R6, panic_argp(R3)
+				// end:
+				//	NOP
+				//
+				// The NOP is needed to give the jumps somewhere to land.
+				// It is a liblink NOP, not a s390x NOP: it encodes to 0 instruction bytes.
+
+				q = obj.Appendp(ctxt, q)
+
+				q.As = AMOVD
+				q.From.Type = obj.TYPE_MEM
+				q.From.Reg = REGG
+				q.From.Offset = 4 * int64(ctxt.Arch.PtrSize) // G.panic
+				q.To.Type = obj.TYPE_REG
+				q.To.Reg = REG_R3
+
+				q = obj.Appendp(ctxt, q)
+				q.As = ACMP
+				q.From.Type = obj.TYPE_REG
+				q.From.Reg = REG_R3
+				q.To.Type = obj.TYPE_CONST
+				q.To.Offset = 0
+
+				q = obj.Appendp(ctxt, q)
+				q.As = ABEQ
+				q.To.Type = obj.TYPE_BRANCH
+				p1 = q
+
+				q = obj.Appendp(ctxt, q)
+				q.As = AMOVD
+				q.From.Type = obj.TYPE_MEM
+				q.From.Reg = REG_R3
+				q.From.Offset = 0 // Panic.argp
+				q.To.Type = obj.TYPE_REG
+				q.To.Reg = REG_R4
+
+				q = obj.Appendp(ctxt, q)
+				q.As = AADD
+				q.From.Type = obj.TYPE_CONST
+				q.From.Offset = int64(autosize) + ctxt.FixedFrameSize()
+				q.Reg = REGSP
+				q.To.Type = obj.TYPE_REG
+				q.To.Reg = REG_R5
+
+				q = obj.Appendp(ctxt, q)
+				q.As = ACMP
+				q.From.Type = obj.TYPE_REG
+				q.From.Reg = REG_R4
+				q.To.Type = obj.TYPE_REG
+				q.To.Reg = REG_R5
+
+				q = obj.Appendp(ctxt, q)
+				q.As = ABNE
+				q.To.Type = obj.TYPE_BRANCH
+				p2 = q
+
+				q = obj.Appendp(ctxt, q)
+				q.As = AADD
+				q.From.Type = obj.TYPE_CONST
+				q.From.Offset = ctxt.FixedFrameSize()
+				q.Reg = REGSP
+				q.To.Type = obj.TYPE_REG
+				q.To.Reg = REG_R6
+
+				q = obj.Appendp(ctxt, q)
+				q.As = AMOVD
+				q.From.Type = obj.TYPE_REG
+				q.From.Reg = REG_R6
+				q.To.Type = obj.TYPE_MEM
+				q.To.Reg = REG_R3
+				q.To.Offset = 0 // Panic.argp
+
+				q = obj.Appendp(ctxt, q)
+
+				q.As = obj.ANOP
+				p1.Pcond = q
+				p2.Pcond = q
+			}
+
+		case obj.ARET:
+			if p.From.Type == obj.TYPE_CONST {
+				ctxt.Diag("using BECOME (%v) is not supported!", p)
+				break
+			}
+
+			retTarget := p.To.Sym
+
+			if cursym.Text.Mark&LEAF != 0 {
+				if autosize == 0 {
+					p.As = ABR
+					p.From = obj.Addr{}
+					if retTarget == nil {
+						p.To.Type = obj.TYPE_REG
+						p.To.Reg = REG_LR
+					} else {
+						p.To.Type = obj.TYPE_BRANCH
+						p.To.Sym = retTarget
+					}
+					p.Mark |= BRANCH
+					break
+				}
+
+				p.As = AADD
+				p.From.Type = obj.TYPE_CONST
+				p.From.Offset = int64(autosize)
+				p.To.Type = obj.TYPE_REG
+				p.To.Reg = REGSP
+				p.Spadj = -autosize
+
+				q = obj.Appendp(ctxt, p)
+				q.As = ABR
+				q.From = obj.Addr{}
+				q.To.Type = obj.TYPE_REG
+				q.To.Reg = REG_LR
+				q.Mark |= BRANCH
+				q.Spadj = autosize
+				break
+			}
+
+			p.As = AMOVD
+			p.From.Type = obj.TYPE_MEM
+			p.From.Reg = REGSP
+			p.From.Offset = 0
+			p.To.Type = obj.TYPE_REG
+			p.To.Reg = REG_LR
+
+			q = p
+
+			if autosize != 0 {
+				q = obj.Appendp(ctxt, q)
+				q.As = AADD
+				q.From.Type = obj.TYPE_CONST
+				q.From.Offset = int64(autosize)
+				q.To.Type = obj.TYPE_REG
+				q.To.Reg = REGSP
+				q.Spadj = -autosize
+			}
+
+			q = obj.Appendp(ctxt, q)
+			q.As = ABR
+			q.From = obj.Addr{}
+			if retTarget == nil {
+				q.To.Type = obj.TYPE_REG
+				q.To.Reg = REG_LR
+			} else {
+				q.To.Type = obj.TYPE_BRANCH
+				q.To.Sym = retTarget
+			}
+			q.Mark |= BRANCH
+			q.Spadj = autosize
+
+		case AADD:
+			if p.To.Type == obj.TYPE_REG && p.To.Reg == REGSP && p.From.Type == obj.TYPE_CONST {
+				p.Spadj = int32(-p.From.Offset)
+			}
+		}
+	}
+	if wasSplit {
+		pLast = stacksplitPost(ctxt, pLast, pPre, pPreempt, autosize) // emit post part of split check
+	}
+}
+
+/*
+// instruction scheduling
+	if(debug['Q'] == 0)
+		return;
+
+	curtext = nil;
+	q = nil;	// p - 1
+	q1 = firstp;	// top of block
+	o = 0;		// count of instructions
+	for(p = firstp; p != nil; p = p1) {
+		p1 = p->link;
+		o++;
+		if(p->mark & NOSCHED){
+			if(q1 != p){
+				sched(q1, q);
+			}
+			for(; p != nil; p = p->link){
+				if(!(p->mark & NOSCHED))
+					break;
+				q = p;
+			}
+			p1 = p;
+			q1 = p;
+			o = 0;
+			continue;
+		}
+		if(p->mark & (LABEL|SYNC)) {
+			if(q1 != p)
+				sched(q1, q);
+			q1 = p;
+			o = 1;
+		}
+		if(p->mark & (BRANCH|SYNC)) {
+			sched(q1, p);
+			q1 = p1;
+			o = 0;
+		}
+		if(o >= NSCHED) {
+			sched(q1, p);
+			q1 = p1;
+			o = 0;
+		}
+		q = p;
+	}
+*/
+func stacksplitPre(ctxt *obj.Link, p *obj.Prog, framesize int32) (*obj.Prog, *obj.Prog) {
+	var q *obj.Prog
+
+	// MOVD	g_stackguard(g), R3
+	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_R3
+
+	q = nil
+	if framesize <= obj.StackSmall {
+		// small stack: SP < stackguard
+		//	CMP	stackguard, SP
+
+		//p.To.Type = obj.TYPE_REG
+		//p.To.Reg = REGSP
+
+		// q1: BLT	done
+
+		p = obj.Appendp(ctxt, p)
+		//q1 = p
+		p.From.Type = obj.TYPE_REG
+		p.From.Reg = REG_R3
+		p.Reg = REGSP
+		p.As = ACMPUBGE
+		p.To.Type = obj.TYPE_BRANCH
+		//p = obj.Appendp(ctxt, p)
+
+		//p.As = ACMPU
+		//p.From.Type = obj.TYPE_REG
+		//p.From.Reg = REG_R3
+		//p.To.Type = obj.TYPE_REG
+		//p.To.Reg = REGSP
+
+		//p = obj.Appendp(ctxt, p)
+		//p.As = ABGE
+		//p.To.Type = obj.TYPE_BRANCH
+
+	} else if framesize <= obj.StackBig {
+		// large stack: SP-framesize < stackguard-StackSmall
+		//	ADD $-framesize, SP, R4
+		//	CMP stackguard, R4
+		p = obj.Appendp(ctxt, p)
+
+		p.As = AADD
+		p.From.Type = obj.TYPE_CONST
+		p.From.Offset = int64(-framesize)
+		p.Reg = REGSP
+		p.To.Type = obj.TYPE_REG
+		p.To.Reg = REG_R4
+
+		p = obj.Appendp(ctxt, p)
+		p.From.Type = obj.TYPE_REG
+		p.From.Reg = REG_R3
+		p.Reg = REG_R4
+		p.As = ACMPUBGE
+		p.To.Type = obj.TYPE_BRANCH
+
+	} 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.
+		//
+		// Preemption sets stackguard to StackPreempt, a very large value.
+		// That breaks the math above, so we have to check for that explicitly.
+		//	// stackguard is R3
+		//	CMP	R3, $StackPreempt
+		//	BEQ	label-of-call-to-morestack
+		//	ADD	$StackGuard, SP, R4
+		//	SUB	R3, R4
+		//	MOVD	$(framesize+(StackGuard-StackSmall)), TEMP
+		//	CMPUBGE	TEMP, R4
+		p = obj.Appendp(ctxt, p)
+
+		p.As = ACMP
+		p.From.Type = obj.TYPE_REG
+		p.From.Reg = REG_R3
+		p.To.Type = obj.TYPE_CONST
+		p.To.Offset = obj.StackPreempt
+
+		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
+		p.To.Type = obj.TYPE_REG
+		p.To.Reg = REG_R4
+
+		p = obj.Appendp(ctxt, p)
+		p.As = ASUB
+		p.From.Type = obj.TYPE_REG
+		p.From.Reg = REG_R3
+		p.To.Type = obj.TYPE_REG
+		p.To.Reg = REG_R4
+
+		p = obj.Appendp(ctxt, p)
+		p.As = AMOVD
+		p.From.Type = obj.TYPE_CONST
+		p.From.Offset = int64(framesize) + obj.StackGuard - obj.StackSmall
+		p.To.Type = obj.TYPE_REG
+		p.To.Reg = REGTMP
+
+		p = obj.Appendp(ctxt, p)
+		p.From.Type = obj.TYPE_REG
+		p.From.Reg = REGTMP
+		p.Reg = REG_R4
+		p.As = ACMPUBGE
+		p.To.Type = obj.TYPE_BRANCH
+	}
+
+	return p, q
+}
+
+func stacksplitPost(ctxt *obj.Link, p *obj.Prog, pPre *obj.Prog, pPreempt *obj.Prog, framesize int32) *obj.Prog {
+	// Now we are at the end of the function, but logically
+	// we are still in function prologue. We need to fix the
+	// SP data and PCDATA.
+	spfix := obj.Appendp(ctxt, p)
+	spfix.As = obj.ANOP
+	spfix.Spadj = -framesize
+
+	pcdata := obj.Appendp(ctxt, spfix)
+	pcdata.Lineno = ctxt.Cursym.Text.Lineno
+	pcdata.Mode = ctxt.Cursym.Text.Mode
+	pcdata.As = obj.APCDATA
+	pcdata.From.Type = obj.TYPE_CONST
+	pcdata.From.Offset = obj.PCDATA_StackMapIndex
+	pcdata.To.Type = obj.TYPE_CONST
+	pcdata.To.Offset = -1 // pcdata starts at -1 at function entry
+
+	// MOVD	LR, R5
+	p = obj.Appendp(ctxt, pcdata)
+	pPre.Pcond = p
+	p.As = AMOVD
+	p.From.Type = obj.TYPE_REG
+	p.From.Reg = REG_LR
+	p.To.Type = obj.TYPE_REG
+	p.To.Reg = REG_R5
+	if pPreempt != nil {
+		pPreempt.Pcond = p
+	}
+
+	// BL	runtime.morestack(SB)
+	p = obj.Appendp(ctxt, p)
+
+	p.As = ABL
+	p.To.Type = obj.TYPE_BRANCH
+	if ctxt.Cursym.CFunc() {
+		p.To.Sym = obj.Linklookup(ctxt, "runtime.morestackc", 0)
+	} else if ctxt.Cursym.Text.From3.Offset&obj.NEEDCTXT == 0 {
+		p.To.Sym = obj.Linklookup(ctxt, "runtime.morestack_noctxt", 0)
+	} else {
+		p.To.Sym = obj.Linklookup(ctxt, "runtime.morestack", 0)
+	}
+
+	// BR	start
+	p = obj.Appendp(ctxt, p)
+
+	p.As = ABR
+	p.To.Type = obj.TYPE_BRANCH
+	p.Pcond = ctxt.Cursym.Text.Link
+	return p
+}
+
+var pc_cnt int64
+
+func follow(ctxt *obj.Link, s *obj.LSym) {
+	ctxt.Cursym = s
+
+	pc_cnt = 0
+	firstp := ctxt.NewProg()
+	lastp := firstp
+	xfol(ctxt, s.Text, &lastp)
+	lastp.Link = nil
+	s.Text = firstp.Link
+}
+
+func relinv(a obj.As) obj.As {
+	switch a {
+	case ABEQ:
+		return ABNE
+	case ABNE:
+		return ABEQ
+
+	case ABGE:
+		return ABLT
+	case ABLT:
+		return ABGE
+
+	case ABGT:
+		return ABLE
+	case ABLE:
+		return ABGT
+
+	case ABVC:
+		return ABVS
+	case ABVS:
+		return ABVC
+	}
+
+	return 0
+}
+
+func xfol(ctxt *obj.Link, p *obj.Prog, last **obj.Prog) {
+	var q *obj.Prog
+	var r *obj.Prog
+	var b obj.As
+
+	for p != nil {
+		a := p.As
+		if a == ABR {
+			q = p.Pcond
+			if (p.Mark&NOSCHED != 0) || q != nil && (q.Mark&NOSCHED != 0) {
+				p.Mark |= FOLL
+				(*last).Link = p
+				*last = p
+				(*last).Pc = pc_cnt
+				pc_cnt += 1
+				p = p.Link
+				xfol(ctxt, p, last)
+				p = q
+				if p != nil && p.Mark&FOLL == 0 {
+					continue
+				}
+				return
+			}
+
+			if q != nil {
+				p.Mark |= FOLL
+				p = q
+				if p.Mark&FOLL == 0 {
+					continue
+				}
+			}
+		}
+
+		if p.Mark&FOLL != 0 {
+			q = p
+			for i := 0; i < 4; i, q = i+1, q.Link {
+				if q == *last || (q.Mark&NOSCHED != 0) {
+					break
+				}
+				b = 0 /* set */
+				a = q.As
+				if a == obj.ANOP {
+					i--
+					continue
+				}
+				if a != ABR && a != obj.ARET {
+					if q.Pcond == nil || (q.Pcond.Mark&FOLL != 0) {
+						continue
+					}
+					b = relinv(a)
+					if b == 0 {
+						continue
+					}
+				}
+
+				for {
+					r = ctxt.NewProg()
+					*r = *p
+					if r.Mark&FOLL == 0 {
+						fmt.Printf("can't happen 1\n")
+					}
+					r.Mark |= FOLL
+					if p != q {
+						p = p.Link
+						(*last).Link = r
+						*last = r
+						(*last).Pc = pc_cnt
+						pc_cnt += 1
+						continue
+					}
+
+					(*last).Link = r
+					*last = r
+					(*last).Pc = pc_cnt
+					pc_cnt += 1
+					if a == ABR || a == obj.ARET {
+						return
+					}
+					r.As = b
+					r.Pcond = p.Link
+					r.Link = p.Pcond
+					if r.Link.Mark&FOLL == 0 {
+						xfol(ctxt, r.Link, last)
+					}
+					if r.Pcond.Mark&FOLL == 0 {
+						fmt.Printf("can't happen 2\n")
+					}
+					return
+				}
+			}
+
+			a = ABR
+			q = ctxt.NewProg()
+			q.As = a
+			q.Lineno = p.Lineno
+			q.To.Type = obj.TYPE_BRANCH
+			q.To.Offset = p.Pc
+			q.Pcond = p
+			p = q
+		}
+
+		p.Mark |= FOLL
+		(*last).Link = p
+		*last = p
+		(*last).Pc = pc_cnt
+		pc_cnt += 1
+
+		if a == ABR || a == obj.ARET {
+			if p.Mark&NOSCHED != 0 {
+				p = p.Link
+				continue
+			}
+
+			return
+		}
+
+		if p.Pcond != nil {
+			if a != ABL && p.Link != nil {
+				xfol(ctxt, p.Link, last)
+				p = p.Pcond
+				if p == nil || (p.Mark&FOLL != 0) {
+					return
+				}
+				continue
+			}
+		}
+
+		p = p.Link
+	}
+}
+
+var unaryDst = map[obj.As]bool{
+	ASTCK:  true,
+	ASTCKC: true,
+	ASTCKE: true,
+	ASTCKF: true,
+	ANEG:   true,
+	ANEGW:  true,
+	AVONE:  true,
+	AVZERO: true,
+}
+
+var Links390x = obj.LinkArch{
+	Arch:       sys.ArchS390X,
+	Preprocess: preprocess,
+	Assemble:   spanz,
+	Follow:     follow,
+	Progedit:   progedit,
+	UnaryDst:   unaryDst,
+}