Adding upstream version 1.16.10.upstream/1.16.10upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 786 insertions, 0 deletions

diff --git a/src/cmd/internal/obj/arm/obj5.go b/src/cmd/internal/obj/arm/obj5.go
new file mode 100644
index 0000000..29d3a58
--- /dev/null
+++ b/src/cmd/internal/obj/arm/obj5.go
@@ -0,0 +1,786 @@
+// Derived from Inferno utils/5c/swt.c
+// https://bitbucket.org/inferno-os/inferno-os/src/master/utils/5c/swt.c
+//
+//	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 arm
+
+import (
+	"cmd/internal/obj"
+	"cmd/internal/objabi"
+	"cmd/internal/sys"
+)
+
+var progedit_tlsfallback *obj.LSym
+
+func progedit(ctxt *obj.Link, p *obj.Prog, newprog obj.ProgAlloc) {
+	p.From.Class = 0
+	p.To.Class = 0
+
+	c := ctxt5{ctxt: ctxt, newprog: newprog}
+
+	// Rewrite B/BL to symbol as TYPE_BRANCH.
+	switch p.As {
+	case AB, ABL, obj.ADUFFZERO, obj.ADUFFCOPY:
+		if p.To.Type == obj.TYPE_MEM && (p.To.Name == obj.NAME_EXTERN || p.To.Name == obj.NAME_STATIC) && p.To.Sym != nil {
+			p.To.Type = obj.TYPE_BRANCH
+		}
+	}
+
+	// Replace TLS register fetches on older ARM processors.
+	switch p.As {
+	// Treat MRC 15, 0, <reg>, C13, C0, 3 specially.
+	case AMRC:
+		if p.To.Offset&0xffff0fff == 0xee1d0f70 {
+			// Because the instruction might be rewritten to a BL which returns in R0
+			// the register must be zero.
+			if p.To.Offset&0xf000 != 0 {
+				ctxt.Diag("%v: TLS MRC instruction must write to R0 as it might get translated into a BL instruction", p.Line())
+			}
+
+			if objabi.GOARM < 7 {
+				// Replace it with BL runtime.read_tls_fallback(SB) for ARM CPUs that lack the tls extension.
+				if progedit_tlsfallback == nil {
+					progedit_tlsfallback = ctxt.Lookup("runtime.read_tls_fallback")
+				}
+
+				// MOVW	LR, R11
+				p.As = AMOVW
+
+				p.From.Type = obj.TYPE_REG
+				p.From.Reg = REGLINK
+				p.To.Type = obj.TYPE_REG
+				p.To.Reg = REGTMP
+
+				// BL	runtime.read_tls_fallback(SB)
+				p = obj.Appendp(p, newprog)
+
+				p.As = ABL
+				p.To.Type = obj.TYPE_BRANCH
+				p.To.Sym = progedit_tlsfallback
+				p.To.Offset = 0
+
+				// MOVW	R11, LR
+				p = obj.Appendp(p, newprog)
+
+				p.As = AMOVW
+				p.From.Type = obj.TYPE_REG
+				p.From.Reg = REGTMP
+				p.To.Type = obj.TYPE_REG
+				p.To.Reg = REGLINK
+				break
+			}
+		}
+
+		// Otherwise, MRC/MCR instructions need no further treatment.
+		p.As = AWORD
+	}
+
+	// Rewrite float constants to values stored in memory.
+	switch p.As {
+	case AMOVF:
+		if p.From.Type == obj.TYPE_FCONST && c.chipfloat5(p.From.Val.(float64)) < 0 && (c.chipzero5(p.From.Val.(float64)) < 0 || p.Scond&C_SCOND != C_SCOND_NONE) {
+			f32 := float32(p.From.Val.(float64))
+			p.From.Type = obj.TYPE_MEM
+			p.From.Sym = ctxt.Float32Sym(f32)
+			p.From.Name = obj.NAME_EXTERN
+			p.From.Offset = 0
+		}
+
+	case AMOVD:
+		if p.From.Type == obj.TYPE_FCONST && c.chipfloat5(p.From.Val.(float64)) < 0 && (c.chipzero5(p.From.Val.(float64)) < 0 || p.Scond&C_SCOND != C_SCOND_NONE) {
+			p.From.Type = obj.TYPE_MEM
+			p.From.Sym = ctxt.Float64Sym(p.From.Val.(float64))
+			p.From.Name = obj.NAME_EXTERN
+			p.From.Offset = 0
+		}
+	}
+
+	if ctxt.Flag_dynlink {
+		c.rewriteToUseGot(p)
+	}
+}
+
+// Rewrite p, if necessary, to access global data via the global offset table.
+func (c *ctxt5) rewriteToUseGot(p *obj.Prog) {
+	if p.As == obj.ADUFFCOPY || p.As == obj.ADUFFZERO {
+		//     ADUFFxxx $offset
+		// becomes
+		//     MOVW runtime.duffxxx@GOT, R9
+		//     ADD $offset, R9
+		//     CALL (R9)
+		var sym *obj.LSym
+		if p.As == obj.ADUFFZERO {
+			sym = c.ctxt.Lookup("runtime.duffzero")
+		} else {
+			sym = c.ctxt.Lookup("runtime.duffcopy")
+		}
+		offset := p.To.Offset
+		p.As = AMOVW
+		p.From.Type = obj.TYPE_MEM
+		p.From.Name = obj.NAME_GOTREF
+		p.From.Sym = sym
+		p.To.Type = obj.TYPE_REG
+		p.To.Reg = REG_R9
+		p.To.Name = obj.NAME_NONE
+		p.To.Offset = 0
+		p.To.Sym = nil
+		p1 := obj.Appendp(p, c.newprog)
+		p1.As = AADD
+		p1.From.Type = obj.TYPE_CONST
+		p1.From.Offset = offset
+		p1.To.Type = obj.TYPE_REG
+		p1.To.Reg = REG_R9
+		p2 := obj.Appendp(p1, c.newprog)
+		p2.As = obj.ACALL
+		p2.To.Type = obj.TYPE_MEM
+		p2.To.Reg = REG_R9
+		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() {
+		// MOVW $sym, Rx becomes MOVW sym@GOT, Rx
+		// MOVW $sym+<off>, Rx becomes MOVW sym@GOT, Rx; ADD <off>, Rx
+		if p.As != AMOVW {
+			c.ctxt.Diag("do not know how to handle TYPE_ADDR in %v with -dynlink", p)
+		}
+		if p.To.Type != obj.TYPE_REG {
+			c.ctxt.Diag("do not know how to handle LEAQ-type insn to non-register in %v with -dynlink", p)
+		}
+		p.From.Type = obj.TYPE_MEM
+		p.From.Name = obj.NAME_GOTREF
+		if p.From.Offset != 0 {
+			q := obj.Appendp(p, c.newprog)
+			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.GetFrom3() != nil && p.GetFrom3().Name == obj.NAME_EXTERN {
+		c.ctxt.Diag("don't know how to handle %v with -dynlink", p)
+	}
+	var source *obj.Addr
+	// MOVx sym, Ry becomes MOVW sym@GOT, R9; MOVx (R9), Ry
+	// MOVx Ry, sym becomes MOVW sym@GOT, R9; MOVx Ry, (R9)
+	// 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() {
+			c.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 == objabi.STLSBSS {
+		return
+	}
+	if source.Type != obj.TYPE_MEM {
+		c.ctxt.Diag("don't know how to handle %v with -dynlink", p)
+	}
+	p1 := obj.Appendp(p, c.newprog)
+	p2 := obj.Appendp(p1, c.newprog)
+
+	p1.As = AMOVW
+	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 = REG_R9
+
+	p2.As = p.As
+	p2.From = p.From
+	p2.To = p.To
+	if p.From.Name == obj.NAME_EXTERN {
+		p2.From.Reg = REG_R9
+		p2.From.Name = obj.NAME_NONE
+		p2.From.Sym = nil
+	} else if p.To.Name == obj.NAME_EXTERN {
+		p2.To.Reg = REG_R9
+		p2.To.Name = obj.NAME_NONE
+		p2.To.Sym = nil
+	} else {
+		return
+	}
+	obj.Nopout(p)
+}
+
+// Prog.mark
+const (
+	FOLL  = 1 << 0
+	LABEL = 1 << 1
+	LEAF  = 1 << 2
+)
+
+func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
+	autosize := int32(0)
+
+	if cursym.Func().Text == nil || cursym.Func().Text.Link == nil {
+		return
+	}
+
+	c := ctxt5{ctxt: ctxt, cursym: cursym, newprog: newprog}
+
+	p := c.cursym.Func().Text
+	autoffset := int32(p.To.Offset)
+	if autoffset == -4 {
+		// Historical way to mark NOFRAME.
+		p.From.Sym.Set(obj.AttrNoFrame, true)
+		autoffset = 0
+	}
+	if autoffset < 0 || autoffset%4 != 0 {
+		c.ctxt.Diag("frame size %d not 0 or a positive multiple of 4", autoffset)
+	}
+	if p.From.Sym.NoFrame() {
+		if autoffset != 0 {
+			c.ctxt.Diag("NOFRAME functions must have a frame size of 0, not %d", autoffset)
+		}
+	}
+
+	cursym.Func().Locals = autoffset
+	cursym.Func().Args = p.To.Val.(int32)
+
+	/*
+	 * find leaf subroutines
+	 */
+	for p := cursym.Func().Text; p != nil; p = p.Link {
+		switch p.As {
+		case obj.ATEXT:
+			p.Mark |= LEAF
+
+		case ADIV, ADIVU, AMOD, AMODU:
+			cursym.Func().Text.Mark &^= LEAF
+
+		case ABL,
+			ABX,
+			obj.ADUFFZERO,
+			obj.ADUFFCOPY:
+			cursym.Func().Text.Mark &^= LEAF
+		}
+	}
+
+	var q2 *obj.Prog
+	for p := cursym.Func().Text; p != nil; p = p.Link {
+		o := p.As
+		switch o {
+		case obj.ATEXT:
+			autosize = autoffset
+
+			if p.Mark&LEAF != 0 && autosize == 0 {
+				// A leaf function with no locals has no frame.
+				p.From.Sym.Set(obj.AttrNoFrame, true)
+			}
+
+			if !p.From.Sym.NoFrame() {
+				// If there is a stack frame at all, it includes
+				// space to save the LR.
+				autosize += 4
+			}
+
+			if autosize == 0 && cursym.Func().Text.Mark&LEAF == 0 {
+				// A very few functions that do not return to their caller
+				// are not identified as leaves but still have no frame.
+				if ctxt.Debugvlog {
+					ctxt.Logf("save suppressed in: %s\n", cursym.Name)
+				}
+
+				cursym.Func().Text.Mark |= LEAF
+			}
+
+			// FP offsets need an updated p.To.Offset.
+			p.To.Offset = int64(autosize) - 4
+
+			if cursym.Func().Text.Mark&LEAF != 0 {
+				cursym.Set(obj.AttrLeaf, true)
+				if p.From.Sym.NoFrame() {
+					break
+				}
+			}
+
+			if !p.From.Sym.NoSplit() {
+				p = c.stacksplit(p, autosize) // emit split check
+			}
+
+			// MOVW.W		R14,$-autosize(SP)
+			p = obj.Appendp(p, c.newprog)
+
+			p.As = AMOVW
+			p.Scond |= C_WBIT
+			p.From.Type = obj.TYPE_REG
+			p.From.Reg = REGLINK
+			p.To.Type = obj.TYPE_MEM
+			p.To.Offset = int64(-autosize)
+			p.To.Reg = REGSP
+			p.Spadj = autosize
+
+			if cursym.Func().Text.From.Sym.Wrapper() {
+				// if(g->panic != nil && g->panic->argp == FP) g->panic->argp = bottom-of-frame
+				//
+				//	MOVW g_panic(g), R1
+				//	CMP  $0, R1
+				//	B.NE checkargp
+				// end:
+				//	NOP
+				// ... function ...
+				// checkargp:
+				//	MOVW panic_argp(R1), R2
+				//	ADD  $(autosize+4), R13, R3
+				//	CMP  R2, R3
+				//	B.NE end
+				//	ADD  $4, R13, R4
+				//	MOVW R4, panic_argp(R1)
+				//	B    end
+				//
+				// The NOP is needed to give the jumps somewhere to land.
+				// It is a liblink NOP, not an ARM NOP: it encodes to 0 instruction bytes.
+
+				p = obj.Appendp(p, newprog)
+				p.As = AMOVW
+				p.From.Type = obj.TYPE_MEM
+				p.From.Reg = REGG
+				p.From.Offset = 4 * int64(ctxt.Arch.PtrSize) // G.panic
+				p.To.Type = obj.TYPE_REG
+				p.To.Reg = REG_R1
+
+				p = obj.Appendp(p, newprog)
+				p.As = ACMP
+				p.From.Type = obj.TYPE_CONST
+				p.From.Offset = 0
+				p.Reg = REG_R1
+
+				// B.NE checkargp
+				bne := obj.Appendp(p, newprog)
+				bne.As = ABNE
+				bne.To.Type = obj.TYPE_BRANCH
+
+				// end: NOP
+				end := obj.Appendp(bne, newprog)
+				end.As = obj.ANOP
+
+				// find end of function
+				var last *obj.Prog
+				for last = end; last.Link != nil; last = last.Link {
+				}
+
+				// MOVW panic_argp(R1), R2
+				mov := obj.Appendp(last, newprog)
+				mov.As = AMOVW
+				mov.From.Type = obj.TYPE_MEM
+				mov.From.Reg = REG_R1
+				mov.From.Offset = 0 // Panic.argp
+				mov.To.Type = obj.TYPE_REG
+				mov.To.Reg = REG_R2
+
+				// B.NE branch target is MOVW above
+				bne.To.SetTarget(mov)
+
+				// ADD $(autosize+4), R13, R3
+				p = obj.Appendp(mov, newprog)
+				p.As = AADD
+				p.From.Type = obj.TYPE_CONST
+				p.From.Offset = int64(autosize) + 4
+				p.Reg = REG_R13
+				p.To.Type = obj.TYPE_REG
+				p.To.Reg = REG_R3
+
+				// CMP R2, R3
+				p = obj.Appendp(p, newprog)
+				p.As = ACMP
+				p.From.Type = obj.TYPE_REG
+				p.From.Reg = REG_R2
+				p.Reg = REG_R3
+
+				// B.NE end
+				p = obj.Appendp(p, newprog)
+				p.As = ABNE
+				p.To.Type = obj.TYPE_BRANCH
+				p.To.SetTarget(end)
+
+				// ADD $4, R13, R4
+				p = obj.Appendp(p, newprog)
+				p.As = AADD
+				p.From.Type = obj.TYPE_CONST
+				p.From.Offset = 4
+				p.Reg = REG_R13
+				p.To.Type = obj.TYPE_REG
+				p.To.Reg = REG_R4
+
+				// MOVW R4, panic_argp(R1)
+				p = obj.Appendp(p, newprog)
+				p.As = AMOVW
+				p.From.Type = obj.TYPE_REG
+				p.From.Reg = REG_R4
+				p.To.Type = obj.TYPE_MEM
+				p.To.Reg = REG_R1
+				p.To.Offset = 0 // Panic.argp
+
+				// B end
+				p = obj.Appendp(p, newprog)
+				p.As = AB
+				p.To.Type = obj.TYPE_BRANCH
+				p.To.SetTarget(end)
+
+				// reset for subsequent passes
+				p = end
+			}
+
+		case obj.ARET:
+			nocache(p)
+			if cursym.Func().Text.Mark&LEAF != 0 {
+				if autosize == 0 {
+					p.As = AB
+					p.From = obj.Addr{}
+					if p.To.Sym != nil { // retjmp
+						p.To.Type = obj.TYPE_BRANCH
+					} else {
+						p.To.Type = obj.TYPE_MEM
+						p.To.Offset = 0
+						p.To.Reg = REGLINK
+					}
+
+					break
+				}
+			}
+
+			p.As = AMOVW
+			p.Scond |= C_PBIT
+			p.From.Type = obj.TYPE_MEM
+			p.From.Offset = int64(autosize)
+			p.From.Reg = REGSP
+			p.To.Type = obj.TYPE_REG
+			p.To.Reg = REGPC
+
+			// If there are instructions following
+			// this ARET, they come from a branch
+			// with the same stackframe, so no spadj.
+
+			if p.To.Sym != nil { // retjmp
+				p.To.Reg = REGLINK
+				q2 = obj.Appendp(p, newprog)
+				q2.As = AB
+				q2.To.Type = obj.TYPE_BRANCH
+				q2.To.Sym = p.To.Sym
+				p.To.Sym = nil
+				p.To.Name = obj.NAME_NONE
+				p = q2
+			}
+
+		case AADD:
+			if p.From.Type == obj.TYPE_CONST && p.From.Reg == 0 && p.To.Type == obj.TYPE_REG && p.To.Reg == REGSP {
+				p.Spadj = int32(-p.From.Offset)
+			}
+
+		case ASUB:
+			if p.From.Type == obj.TYPE_CONST && p.From.Reg == 0 && p.To.Type == obj.TYPE_REG && p.To.Reg == REGSP {
+				p.Spadj = int32(p.From.Offset)
+			}
+
+		case ADIV, ADIVU, AMOD, AMODU:
+			if cursym.Func().Text.From.Sym.NoSplit() {
+				ctxt.Diag("cannot divide in NOSPLIT function")
+			}
+			const debugdivmod = false
+			if debugdivmod {
+				break
+			}
+			if p.From.Type != obj.TYPE_REG {
+				break
+			}
+			if p.To.Type != obj.TYPE_REG {
+				break
+			}
+
+			// Make copy because we overwrite p below.
+			q1 := *p
+			if q1.Reg == REGTMP || q1.Reg == 0 && q1.To.Reg == REGTMP {
+				ctxt.Diag("div already using REGTMP: %v", p)
+			}
+
+			/* MOV m(g),REGTMP */
+			p.As = AMOVW
+			p.Pos = q1.Pos
+			p.From.Type = obj.TYPE_MEM
+			p.From.Reg = REGG
+			p.From.Offset = 6 * 4 // offset of g.m
+			p.Reg = 0
+			p.To.Type = obj.TYPE_REG
+			p.To.Reg = REGTMP
+
+			/* MOV a,m_divmod(REGTMP) */
+			p = obj.Appendp(p, newprog)
+			p.As = AMOVW
+			p.Pos = q1.Pos
+			p.From.Type = obj.TYPE_REG
+			p.From.Reg = q1.From.Reg
+			p.To.Type = obj.TYPE_MEM
+			p.To.Reg = REGTMP
+			p.To.Offset = 8 * 4 // offset of m.divmod
+
+			/* MOV b, R8 */
+			p = obj.Appendp(p, newprog)
+			p.As = AMOVW
+			p.Pos = q1.Pos
+			p.From.Type = obj.TYPE_REG
+			p.From.Reg = q1.Reg
+			if q1.Reg == 0 {
+				p.From.Reg = q1.To.Reg
+			}
+			p.To.Type = obj.TYPE_REG
+			p.To.Reg = REG_R8
+			p.To.Offset = 0
+
+			/* CALL appropriate */
+			p = obj.Appendp(p, newprog)
+			p.As = ABL
+			p.Pos = q1.Pos
+			p.To.Type = obj.TYPE_BRANCH
+			switch o {
+			case ADIV:
+				p.To.Sym = symdiv
+			case ADIVU:
+				p.To.Sym = symdivu
+			case AMOD:
+				p.To.Sym = symmod
+			case AMODU:
+				p.To.Sym = symmodu
+			}
+
+			/* MOV REGTMP, b */
+			p = obj.Appendp(p, newprog)
+			p.As = AMOVW
+			p.Pos = q1.Pos
+			p.From.Type = obj.TYPE_REG
+			p.From.Reg = REGTMP
+			p.From.Offset = 0
+			p.To.Type = obj.TYPE_REG
+			p.To.Reg = q1.To.Reg
+
+		case AMOVW:
+			if (p.Scond&C_WBIT != 0) && p.To.Type == obj.TYPE_MEM && p.To.Reg == REGSP {
+				p.Spadj = int32(-p.To.Offset)
+			}
+			if (p.Scond&C_PBIT != 0) && p.From.Type == obj.TYPE_MEM && p.From.Reg == REGSP && p.To.Reg != REGPC {
+				p.Spadj = int32(-p.From.Offset)
+			}
+			if p.From.Type == obj.TYPE_ADDR && p.From.Reg == REGSP && p.To.Type == obj.TYPE_REG && p.To.Reg == REGSP {
+				p.Spadj = int32(-p.From.Offset)
+			}
+
+		case obj.AGETCALLERPC:
+			if cursym.Leaf() {
+				/* MOVW LR, Rd */
+				p.As = AMOVW
+				p.From.Type = obj.TYPE_REG
+				p.From.Reg = REGLINK
+			} else {
+				/* MOVW (RSP), Rd */
+				p.As = AMOVW
+				p.From.Type = obj.TYPE_MEM
+				p.From.Reg = REGSP
+			}
+		}
+	}
+}
+
+func (c *ctxt5) stacksplit(p *obj.Prog, framesize int32) *obj.Prog {
+	// MOVW g_stackguard(g), R1
+	p = obj.Appendp(p, c.newprog)
+
+	p.As = AMOVW
+	p.From.Type = obj.TYPE_MEM
+	p.From.Reg = REGG
+	p.From.Offset = 2 * int64(c.ctxt.Arch.PtrSize) // G.stackguard0
+	if c.cursym.CFunc() {
+		p.From.Offset = 3 * int64(c.ctxt.Arch.PtrSize) // G.stackguard1
+	}
+	p.To.Type = obj.TYPE_REG
+	p.To.Reg = REG_R1
+
+	// Mark the stack bound check and morestack call async nonpreemptible.
+	// If we get preempted here, when resumed the preemption request is
+	// cleared, but we'll still call morestack, which will double the stack
+	// unnecessarily. See issue #35470.
+	p = c.ctxt.StartUnsafePoint(p, c.newprog)
+
+	if framesize <= objabi.StackSmall {
+		// small stack: SP < stackguard
+		//	CMP	stackguard, SP
+		p = obj.Appendp(p, c.newprog)
+
+		p.As = ACMP
+		p.From.Type = obj.TYPE_REG
+		p.From.Reg = REG_R1
+		p.Reg = REGSP
+	} else if framesize <= objabi.StackBig {
+		// large stack: SP-framesize < stackguard-StackSmall
+		//	MOVW $-(framesize-StackSmall)(SP), R2
+		//	CMP stackguard, R2
+		p = obj.Appendp(p, c.newprog)
+
+		p.As = AMOVW
+		p.From.Type = obj.TYPE_ADDR
+		p.From.Reg = REGSP
+		p.From.Offset = -(int64(framesize) - objabi.StackSmall)
+		p.To.Type = obj.TYPE_REG
+		p.To.Reg = REG_R2
+
+		p = obj.Appendp(p, c.newprog)
+		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
+		//	MOVW.NE $StackGuard(SP), R2
+		//	SUB.NE  R1, R2
+		//	MOVW.NE $(framesize+(StackGuard-StackSmall)), R3
+		//	CMP.NE  R3, R2
+		p = obj.Appendp(p, c.newprog)
+
+		p.As = ACMP
+		p.From.Type = obj.TYPE_CONST
+		p.From.Offset = int64(uint32(objabi.StackPreempt & (1<<32 - 1)))
+		p.Reg = REG_R1
+
+		p = obj.Appendp(p, c.newprog)
+		p.As = AMOVW
+		p.From.Type = obj.TYPE_ADDR
+		p.From.Reg = REGSP
+		p.From.Offset = int64(objabi.StackGuard)
+		p.To.Type = obj.TYPE_REG
+		p.To.Reg = REG_R2
+		p.Scond = C_SCOND_NE
+
+		p = obj.Appendp(p, c.newprog)
+		p.As = ASUB
+		p.From.Type = obj.TYPE_REG
+		p.From.Reg = REG_R1
+		p.To.Type = obj.TYPE_REG
+		p.To.Reg = REG_R2
+		p.Scond = C_SCOND_NE
+
+		p = obj.Appendp(p, c.newprog)
+		p.As = AMOVW
+		p.From.Type = obj.TYPE_ADDR
+		p.From.Offset = int64(framesize) + (int64(objabi.StackGuard) - objabi.StackSmall)
+		p.To.Type = obj.TYPE_REG
+		p.To.Reg = REG_R3
+		p.Scond = C_SCOND_NE
+
+		p = obj.Appendp(p, c.newprog)
+		p.As = ACMP
+		p.From.Type = obj.TYPE_REG
+		p.From.Reg = REG_R3
+		p.Reg = REG_R2
+		p.Scond = C_SCOND_NE
+	}
+
+	// BLS call-to-morestack
+	bls := obj.Appendp(p, c.newprog)
+	bls.As = ABLS
+	bls.To.Type = obj.TYPE_BRANCH
+
+	end := c.ctxt.EndUnsafePoint(bls, c.newprog, -1)
+
+	var last *obj.Prog
+	for last = c.cursym.Func().Text; last.Link != nil; last = last.Link {
+	}
+
+	// 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(last, c.newprog)
+	spfix.As = obj.ANOP
+	spfix.Spadj = -framesize
+
+	pcdata := c.ctxt.EmitEntryStackMap(c.cursym, spfix, c.newprog)
+	pcdata = c.ctxt.StartUnsafePoint(pcdata, c.newprog)
+
+	// MOVW	LR, R3
+	movw := obj.Appendp(pcdata, c.newprog)
+	movw.As = AMOVW
+	movw.From.Type = obj.TYPE_REG
+	movw.From.Reg = REGLINK
+	movw.To.Type = obj.TYPE_REG
+	movw.To.Reg = REG_R3
+
+	bls.To.SetTarget(movw)
+
+	// BL runtime.morestack
+	call := obj.Appendp(movw, c.newprog)
+	call.As = obj.ACALL
+	call.To.Type = obj.TYPE_BRANCH
+	morestack := "runtime.morestack"
+	switch {
+	case c.cursym.CFunc():
+		morestack = "runtime.morestackc"
+	case !c.cursym.Func().Text.From.Sym.NeedCtxt():
+		morestack = "runtime.morestack_noctxt"
+	}
+	call.To.Sym = c.ctxt.Lookup(morestack)
+
+	pcdata = c.ctxt.EndUnsafePoint(call, c.newprog, -1)
+
+	// B start
+	b := obj.Appendp(pcdata, c.newprog)
+	b.As = obj.AJMP
+	b.To.Type = obj.TYPE_BRANCH
+	b.To.SetTarget(c.cursym.Func().Text.Link)
+	b.Spadj = +framesize
+
+	return end
+}
+
+var unaryDst = map[obj.As]bool{
+	ASWI:  true,
+	AWORD: true,
+}
+
+var Linkarm = obj.LinkArch{
+	Arch:           sys.ArchARM,
+	Init:           buildop,
+	Preprocess:     preprocess,
+	Assemble:       span5,
+	Progedit:       progedit,
+	UnaryDst:       unaryDst,
+	DWARFRegisters: ARMDWARFRegisters,
+}