src/cmd/internal/obj/arm64/obj7.go

   1 // cmd/7l/noop.c, cmd/7l/obj.c, cmd/ld/pass.c from Vita Nuova.
   2 // https://code.google.com/p/ken-cc/source/browse/
   3 //
   4 //      Copyright © 1994-1999 Lucent Technologies Inc. All rights reserved.
   5 //      Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
   6 //      Portions Copyright © 1997-1999 Vita Nuova Limited
   7 //      Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
   8 //      Portions Copyright © 2004,2006 Bruce Ellis
   9 //      Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
  10 //      Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
  11 //      Portions Copyright © 2009 The Go Authors. All rights reserved.
  12 //
  13 // Permission is hereby granted, free of charge, to any person obtaining a copy
  14 // of this software and associated documentation files (the "Software"), to deal
  15 // in the Software without restriction, including without limitation the rights
  16 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  17 // copies of the Software, and to permit persons to whom the Software is
  18 // furnished to do so, subject to the following conditions:
  19 //
  20 // The above copyright notice and this permission notice shall be included in
  21 // all copies or substantial portions of the Software.
  22 //
  23 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  24 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  25 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
  26 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  27 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  28 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  29 // THE SOFTWARE.
  30
  31 package arm64
  32
  33 import (
  34         "cmd/internal/obj"
  35         "cmd/internal/objabi"
  36         "cmd/internal/src"
  37         "cmd/internal/sys"
  38         "internal/buildcfg"
  39         "log"
  40         "math"
  41 )
  42
  43 var complements = []obj.As{
  44         AADD:  ASUB,
  45         AADDW: ASUBW,
  46         ASUB:  AADD,
  47         ASUBW: AADDW,
  48         ACMP:  ACMN,
  49         ACMPW: ACMNW,
  50         ACMN:  ACMP,
  51         ACMNW: ACMPW,
  52 }
  53
  54 func (c *ctxt7) stacksplit(p *obj.Prog, framesize int32) *obj.Prog {
  55         // MOV  g_stackguard(g), R1
  56         p = obj.Appendp(p, c.newprog)
  57
  58         p.As = AMOVD
  59         p.From.Type = obj.TYPE_MEM
  60         p.From.Reg = REGG
  61         p.From.Offset = 2 * int64(c.ctxt.Arch.PtrSize) // G.stackguard0
  62         if c.cursym.CFunc() {
  63                 p.From.Offset = 3 * int64(c.ctxt.Arch.PtrSize) // G.stackguard1
  64         }
  65         p.To.Type = obj.TYPE_REG
  66         p.To.Reg = REG_R1
  67
  68         // Mark the stack bound check and morestack call async nonpreemptible.
  69         // If we get preempted here, when resumed the preemption request is
  70         // cleared, but we'll still call morestack, which will double the stack
  71         // unnecessarily. See issue #35470.
  72         p = c.ctxt.StartUnsafePoint(p, c.newprog)
  73
  74         q := (*obj.Prog)(nil)
  75         if framesize <= objabi.StackSmall {
  76                 // small stack: SP < stackguard
  77                 //      MOV     SP, R2
  78                 //      CMP     stackguard, R2
  79                 p = obj.Appendp(p, c.newprog)
  80
  81                 p.As = AMOVD
  82                 p.From.Type = obj.TYPE_REG
  83                 p.From.Reg = REGSP
  84                 p.To.Type = obj.TYPE_REG
  85                 p.To.Reg = REG_R2
  86
  87                 p = obj.Appendp(p, c.newprog)
  88                 p.As = ACMP
  89                 p.From.Type = obj.TYPE_REG
  90                 p.From.Reg = REG_R1
  91                 p.Reg = REG_R2
  92         } else if framesize <= objabi.StackBig {
  93                 // large stack: SP-framesize < stackguard-StackSmall
  94                 //      SUB     $(framesize-StackSmall), SP, R2
  95                 //      CMP     stackguard, R2
  96                 p = obj.Appendp(p, c.newprog)
  97
  98                 p.As = ASUB
  99                 p.From.Type = obj.TYPE_CONST
 100                 p.From.Offset = int64(framesize) - objabi.StackSmall
 101                 p.Reg = REGSP
 102                 p.To.Type = obj.TYPE_REG
 103                 p.To.Reg = REG_R2
 104
 105                 p = obj.Appendp(p, c.newprog)
 106                 p.As = ACMP
 107                 p.From.Type = obj.TYPE_REG
 108                 p.From.Reg = REG_R1
 109                 p.Reg = REG_R2
 110         } else {
 111                 // Such a large stack we need to protect against underflow.
 112                 // The runtime guarantees SP > objabi.StackBig, but
 113                 // framesize is large enough that SP-framesize may
 114                 // underflow, causing a direct comparison with the
 115                 // stack guard to incorrectly succeed. We explicitly
 116                 // guard against underflow.
 117                 //
 118                 //      SUBS    $(framesize-StackSmall), SP, R2
 119                 //      // On underflow, jump to morestack
 120                 //      BLO     label_of_call_to_morestack
 121                 //      CMP     stackguard, R2
 122
 123                 p = obj.Appendp(p, c.newprog)
 124                 p.As = ASUBS
 125                 p.From.Type = obj.TYPE_CONST
 126                 p.From.Offset = int64(framesize) - objabi.StackSmall
 127                 p.Reg = REGSP
 128                 p.To.Type = obj.TYPE_REG
 129                 p.To.Reg = REG_R2
 130
 131                 p = obj.Appendp(p, c.newprog)
 132                 q = p
 133                 p.As = ABLO
 134                 p.To.Type = obj.TYPE_BRANCH
 135
 136                 p = obj.Appendp(p, c.newprog)
 137                 p.As = ACMP
 138                 p.From.Type = obj.TYPE_REG
 139                 p.From.Reg = REG_R1
 140                 p.Reg = REG_R2
 141         }
 142
 143         // BLS  do-morestack
 144         bls := obj.Appendp(p, c.newprog)
 145         bls.As = ABLS
 146         bls.To.Type = obj.TYPE_BRANCH
 147
 148         end := c.ctxt.EndUnsafePoint(bls, c.newprog, -1)
 149
 150         var last *obj.Prog
 151         for last = c.cursym.Func().Text; last.Link != nil; last = last.Link {
 152         }
 153
 154         // Now we are at the end of the function, but logically
 155         // we are still in function prologue. We need to fix the
 156         // SP data and PCDATA.
 157         spfix := obj.Appendp(last, c.newprog)
 158         spfix.As = obj.ANOP
 159         spfix.Spadj = -framesize
 160
 161         pcdata := c.ctxt.EmitEntryStackMap(c.cursym, spfix, c.newprog)
 162         pcdata = c.ctxt.StartUnsafePoint(pcdata, c.newprog)
 163
 164         // MOV  LR, R3
 165         movlr := obj.Appendp(pcdata, c.newprog)
 166         movlr.As = AMOVD
 167         movlr.From.Type = obj.TYPE_REG
 168         movlr.From.Reg = REGLINK
 169         movlr.To.Type = obj.TYPE_REG
 170         movlr.To.Reg = REG_R3
 171         if q != nil {
 172                 q.To.SetTarget(movlr)
 173         }
 174         bls.To.SetTarget(movlr)
 175
 176         debug := movlr
 177         if false {
 178                 debug = obj.Appendp(debug, c.newprog)
 179                 debug.As = AMOVD
 180                 debug.From.Type = obj.TYPE_CONST
 181                 debug.From.Offset = int64(framesize)
 182                 debug.To.Type = obj.TYPE_REG
 183                 debug.To.Reg = REGTMP
 184         }
 185
 186         // BL   runtime.morestack(SB)
 187         call := obj.Appendp(debug, c.newprog)
 188         call.As = ABL
 189         call.To.Type = obj.TYPE_BRANCH
 190         morestack := "runtime.morestack"
 191         switch {
 192         case c.cursym.CFunc():
 193                 morestack = "runtime.morestackc"
 194         case !c.cursym.Func().Text.From.Sym.NeedCtxt():
 195                 morestack = "runtime.morestack_noctxt"
 196         }
 197         call.To.Sym = c.ctxt.Lookup(morestack)
 198
 199         pcdata = c.ctxt.EndUnsafePoint(call, c.newprog, -1)
 200
 201         // B    start
 202         jmp := obj.Appendp(pcdata, c.newprog)
 203         jmp.As = AB
 204         jmp.To.Type = obj.TYPE_BRANCH
 205         jmp.To.SetTarget(c.cursym.Func().Text.Link)
 206         jmp.Spadj = +framesize
 207
 208         return end
 209 }
 210
 211 func progedit(ctxt *obj.Link, p *obj.Prog, newprog obj.ProgAlloc) {
 212         c := ctxt7{ctxt: ctxt, newprog: newprog}
 213
 214         p.From.Class = 0
 215         p.To.Class = 0
 216
 217         // $0 results in C_ZCON, which matches both C_REG and various
 218         // C_xCON, however the C_REG cases in asmout don't expect a
 219         // constant, so they will use the register fields and assemble
 220         // a R0. To prevent that, rewrite $0 as ZR.
 221         if p.From.Type == obj.TYPE_CONST && p.From.Offset == 0 {
 222                 p.From.Type = obj.TYPE_REG
 223                 p.From.Reg = REGZERO
 224         }
 225         if p.To.Type == obj.TYPE_CONST && p.To.Offset == 0 {
 226                 p.To.Type = obj.TYPE_REG
 227                 p.To.Reg = REGZERO
 228         }
 229
 230         // Rewrite BR/BL to symbol as TYPE_BRANCH.
 231         switch p.As {
 232         case AB,
 233                 ABL,
 234                 obj.ARET,
 235                 obj.ADUFFZERO,
 236                 obj.ADUFFCOPY:
 237                 if p.To.Sym != nil {
 238                         p.To.Type = obj.TYPE_BRANCH
 239                 }
 240                 break
 241         }
 242
 243         // Rewrite float constants to values stored in memory.
 244         switch p.As {
 245         case AFMOVS:
 246                 if p.From.Type == obj.TYPE_FCONST {
 247                         f64 := p.From.Val.(float64)
 248                         f32 := float32(f64)
 249                         if c.chipfloat7(f64) > 0 {
 250                                 break
 251                         }
 252                         if math.Float32bits(f32) == 0 {
 253                                 p.From.Type = obj.TYPE_REG
 254                                 p.From.Reg = REGZERO
 255                                 break
 256                         }
 257                         p.From.Type = obj.TYPE_MEM
 258                         p.From.Sym = c.ctxt.Float32Sym(f32)
 259                         p.From.Name = obj.NAME_EXTERN
 260                         p.From.Offset = 0
 261                 }
 262
 263         case AFMOVD:
 264                 if p.From.Type == obj.TYPE_FCONST {
 265                         f64 := p.From.Val.(float64)
 266                         if c.chipfloat7(f64) > 0 {
 267                                 break
 268                         }
 269                         if math.Float64bits(f64) == 0 {
 270                                 p.From.Type = obj.TYPE_REG
 271                                 p.From.Reg = REGZERO
 272                                 break
 273                         }
 274                         p.From.Type = obj.TYPE_MEM
 275                         p.From.Sym = c.ctxt.Float64Sym(f64)
 276                         p.From.Name = obj.NAME_EXTERN
 277                         p.From.Offset = 0
 278                 }
 279
 280                 break
 281         }
 282
 283         // Rewrite negative immediates as positive immediates with
 284         // complementary instruction.
 285         switch p.As {
 286         case AADD, ASUB, ACMP, ACMN:
 287                 if p.From.Type == obj.TYPE_CONST && p.From.Offset < 0 && p.From.Offset != -1<<63 {
 288                         p.From.Offset = -p.From.Offset
 289                         p.As = complements[p.As]
 290                 }
 291         case AADDW, ASUBW, ACMPW, ACMNW:
 292                 if p.From.Type == obj.TYPE_CONST && p.From.Offset < 0 && int32(p.From.Offset) != -1<<31 {
 293                         p.From.Offset = -p.From.Offset
 294                         p.As = complements[p.As]
 295                 }
 296         }
 297
 298         // For 32-bit instruction with constant, rewrite
 299         // the high 32-bit to be a repetition of the low
 300         // 32-bit, so that the BITCON test can be shared
 301         // for both 32-bit and 64-bit. 32-bit ops will
 302         // zero the high 32-bit of the destination register
 303         // anyway.
 304         if (isANDWop(p.As) || isADDWop(p.As) || p.As == AMOVW) && p.From.Type == obj.TYPE_CONST {
 305                 v := p.From.Offset & 0xffffffff
 306                 p.From.Offset = v | v<<32
 307         }
 308
 309         if c.ctxt.Flag_dynlink {
 310                 c.rewriteToUseGot(p)
 311         }
 312 }
 313
 314 // Rewrite p, if necessary, to access global data via the global offset table.
 315 func (c *ctxt7) rewriteToUseGot(p *obj.Prog) {
 316         if p.As == obj.ADUFFCOPY || p.As == obj.ADUFFZERO {
 317                 //     ADUFFxxx $offset
 318                 // becomes
 319                 //     MOVD runtime.duffxxx@GOT, REGTMP
 320                 //     ADD $offset, REGTMP
 321                 //     CALL REGTMP
 322                 var sym *obj.LSym
 323                 if p.As == obj.ADUFFZERO {
 324                         sym = c.ctxt.Lookup("runtime.duffzero")
 325                 } else {
 326                         sym = c.ctxt.Lookup("runtime.duffcopy")
 327                 }
 328                 offset := p.To.Offset
 329                 p.As = AMOVD
 330                 p.From.Type = obj.TYPE_MEM
 331                 p.From.Name = obj.NAME_GOTREF
 332                 p.From.Sym = sym
 333                 p.To.Type = obj.TYPE_REG
 334                 p.To.Reg = REGTMP
 335                 p.To.Name = obj.NAME_NONE
 336                 p.To.Offset = 0
 337                 p.To.Sym = nil
 338                 p1 := obj.Appendp(p, c.newprog)
 339                 p1.As = AADD
 340                 p1.From.Type = obj.TYPE_CONST
 341                 p1.From.Offset = offset
 342                 p1.To.Type = obj.TYPE_REG
 343                 p1.To.Reg = REGTMP
 344                 p2 := obj.Appendp(p1, c.newprog)
 345                 p2.As = obj.ACALL
 346                 p2.To.Type = obj.TYPE_REG
 347                 p2.To.Reg = REGTMP
 348         }
 349
 350         // We only care about global data: NAME_EXTERN means a global
 351         // symbol in the Go sense, and p.Sym.Local is true for a few
 352         // internally defined symbols.
 353         if p.From.Type == obj.TYPE_ADDR && p.From.Name == obj.NAME_EXTERN && !p.From.Sym.Local() {
 354                 // MOVD $sym, Rx becomes MOVD sym@GOT, Rx
 355                 // MOVD $sym+<off>, Rx becomes MOVD sym@GOT, Rx; ADD <off>, Rx
 356                 if p.As != AMOVD {
 357                         c.ctxt.Diag("do not know how to handle TYPE_ADDR in %v with -dynlink", p)
 358                 }
 359                 if p.To.Type != obj.TYPE_REG {
 360                         c.ctxt.Diag("do not know how to handle LEAQ-type insn to non-register in %v with -dynlink", p)
 361                 }
 362                 p.From.Type = obj.TYPE_MEM
 363                 p.From.Name = obj.NAME_GOTREF
 364                 if p.From.Offset != 0 {
 365                         q := obj.Appendp(p, c.newprog)
 366                         q.As = AADD
 367                         q.From.Type = obj.TYPE_CONST
 368                         q.From.Offset = p.From.Offset
 369                         q.To = p.To
 370                         p.From.Offset = 0
 371                 }
 372         }
 373         if p.GetFrom3() != nil && p.GetFrom3().Name == obj.NAME_EXTERN {
 374                 c.ctxt.Diag("don't know how to handle %v with -dynlink", p)
 375         }
 376         var source *obj.Addr
 377         // MOVx sym, Ry becomes MOVD sym@GOT, REGTMP; MOVx (REGTMP), Ry
 378         // MOVx Ry, sym becomes MOVD sym@GOT, REGTMP; MOVD Ry, (REGTMP)
 379         // An addition may be inserted between the two MOVs if there is an offset.
 380         if p.From.Name == obj.NAME_EXTERN && !p.From.Sym.Local() {
 381                 if p.To.Name == obj.NAME_EXTERN && !p.To.Sym.Local() {
 382                         c.ctxt.Diag("cannot handle NAME_EXTERN on both sides in %v with -dynlink", p)
 383                 }
 384                 source = &p.From
 385         } else if p.To.Name == obj.NAME_EXTERN && !p.To.Sym.Local() {
 386                 source = &p.To
 387         } else {
 388                 return
 389         }
 390         if p.As == obj.ATEXT || p.As == obj.AFUNCDATA || p.As == obj.ACALL || p.As == obj.ARET || p.As == obj.AJMP {
 391                 return
 392         }
 393         if source.Sym.Type == objabi.STLSBSS {
 394                 return
 395         }
 396         if source.Type != obj.TYPE_MEM {
 397                 c.ctxt.Diag("don't know how to handle %v with -dynlink", p)
 398         }
 399         p1 := obj.Appendp(p, c.newprog)
 400         p2 := obj.Appendp(p1, c.newprog)
 401         p1.As = AMOVD
 402         p1.From.Type = obj.TYPE_MEM
 403         p1.From.Sym = source.Sym
 404         p1.From.Name = obj.NAME_GOTREF
 405         p1.To.Type = obj.TYPE_REG
 406         p1.To.Reg = REGTMP
 407
 408         p2.As = p.As
 409         p2.From = p.From
 410         p2.To = p.To
 411         if p.From.Name == obj.NAME_EXTERN {
 412                 p2.From.Reg = REGTMP
 413                 p2.From.Name = obj.NAME_NONE
 414                 p2.From.Sym = nil
 415         } else if p.To.Name == obj.NAME_EXTERN {
 416                 p2.To.Reg = REGTMP
 417                 p2.To.Name = obj.NAME_NONE
 418                 p2.To.Sym = nil
 419         } else {
 420                 return
 421         }
 422         obj.Nopout(p)
 423 }
 424
 425 func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
 426         if cursym.Func().Text == nil || cursym.Func().Text.Link == nil {
 427                 return
 428         }
 429
 430         c := ctxt7{ctxt: ctxt, newprog: newprog, cursym: cursym}
 431
 432         p := c.cursym.Func().Text
 433         textstksiz := p.To.Offset
 434         if textstksiz == -8 {
 435                 // Historical way to mark NOFRAME.
 436                 p.From.Sym.Set(obj.AttrNoFrame, true)
 437                 textstksiz = 0
 438         }
 439         if textstksiz < 0 {
 440                 c.ctxt.Diag("negative frame size %d - did you mean NOFRAME?", textstksiz)
 441         }
 442         if p.From.Sym.NoFrame() {
 443                 if textstksiz != 0 {
 444                         c.ctxt.Diag("NOFRAME functions must have a frame size of 0, not %d", textstksiz)
 445                 }
 446         }
 447
 448         c.cursym.Func().Args = p.To.Val.(int32)
 449         c.cursym.Func().Locals = int32(textstksiz)
 450
 451         /*
 452          * find leaf subroutines
 453          */
 454         for p := c.cursym.Func().Text; p != nil; p = p.Link {
 455                 switch p.As {
 456                 case obj.ATEXT:
 457                         p.Mark |= LEAF
 458
 459                 case ABL,
 460                         obj.ADUFFZERO,
 461                         obj.ADUFFCOPY:
 462                         c.cursym.Func().Text.Mark &^= LEAF
 463                 }
 464         }
 465
 466         var q *obj.Prog
 467         var q1 *obj.Prog
 468         var retjmp *obj.LSym
 469         for p := c.cursym.Func().Text; p != nil; p = p.Link {
 470                 o := p.As
 471                 switch o {
 472                 case obj.ATEXT:
 473                         c.cursym.Func().Text = p
 474                         c.autosize = int32(textstksiz)
 475
 476                         if p.Mark&LEAF != 0 && c.autosize == 0 {
 477                                 // A leaf function with no locals has no frame.
 478                                 p.From.Sym.Set(obj.AttrNoFrame, true)
 479                         }
 480
 481                         if !p.From.Sym.NoFrame() {
 482                                 // If there is a stack frame at all, it includes
 483                                 // space to save the LR.
 484                                 c.autosize += 8
 485                         }
 486
 487                         if c.autosize != 0 {
 488                                 extrasize := int32(0)
 489                                 if c.autosize%16 == 8 {
 490                                         // Allocate extra 8 bytes on the frame top to save FP
 491                                         extrasize = 8
 492                                 } else if c.autosize&(16-1) == 0 {
 493                                         // Allocate extra 16 bytes to save FP for the old frame whose size is 8 mod 16
 494                                         extrasize = 16
 495                                 } else {
 496                                         c.ctxt.Diag("%v: unaligned frame size %d - must be 16 aligned", p, c.autosize-8)
 497                                 }
 498                                 c.autosize += extrasize
 499                                 c.cursym.Func().Locals += extrasize
 500
 501                                 // low 32 bits for autosize
 502                                 // high 32 bits for extrasize
 503                                 p.To.Offset = int64(c.autosize) | int64(extrasize)<<32
 504                         } else {
 505                                 // NOFRAME
 506                                 p.To.Offset = 0
 507                         }
 508
 509                         if c.autosize == 0 && c.cursym.Func().Text.Mark&LEAF == 0 {
 510                                 if c.ctxt.Debugvlog {
 511                                         c.ctxt.Logf("save suppressed in: %s\n", c.cursym.Func().Text.From.Sym.Name)
 512                                 }
 513                                 c.cursym.Func().Text.Mark |= LEAF
 514                         }
 515
 516                         if cursym.Func().Text.Mark&LEAF != 0 {
 517                                 cursym.Set(obj.AttrLeaf, true)
 518                                 if p.From.Sym.NoFrame() {
 519                                         break
 520                                 }
 521                         }
 522
 523                         if p.Mark&LEAF != 0 && c.autosize < objabi.StackSmall {
 524                                 // A leaf function with a small stack can be marked
 525                                 // NOSPLIT, avoiding a stack check.
 526                                 p.From.Sym.Set(obj.AttrNoSplit, true)
 527                         }
 528
 529                         if !p.From.Sym.NoSplit() {
 530                                 p = c.stacksplit(p, c.autosize) // emit split check
 531                         }
 532
 533                         var prologueEnd *obj.Prog
 534
 535                         aoffset := c.autosize
 536                         if aoffset > 0xF0 {
 537                                 aoffset = 0xF0
 538                         }
 539
 540                         // Frame is non-empty. Make sure to save link register, even if
 541                         // it is a leaf function, so that traceback works.
 542                         q = p
 543                         if c.autosize > aoffset {
 544                                 // Frame size is too large for a MOVD.W instruction.
 545                                 // Store link register before decrementing SP, so if a signal comes
 546                                 // during the execution of the function prologue, the traceback
 547                                 // code will not see a half-updated stack frame.
 548                                 // This sequence is not async preemptible, as if we open a frame
 549                                 // at the current SP, it will clobber the saved LR.
 550                                 q = c.ctxt.StartUnsafePoint(q, c.newprog)
 551
 552                                 q = obj.Appendp(q, c.newprog)
 553                                 q.Pos = p.Pos
 554                                 q.As = ASUB
 555                                 q.From.Type = obj.TYPE_CONST
 556                                 q.From.Offset = int64(c.autosize)
 557                                 q.Reg = REGSP
 558                                 q.To.Type = obj.TYPE_REG
 559                                 q.To.Reg = REGTMP
 560
 561                                 prologueEnd = q
 562
 563                                 q = obj.Appendp(q, c.newprog)
 564                                 q.Pos = p.Pos
 565                                 q.As = AMOVD
 566                                 q.From.Type = obj.TYPE_REG
 567                                 q.From.Reg = REGLINK
 568                                 q.To.Type = obj.TYPE_MEM
 569                                 q.To.Reg = REGTMP
 570
 571                                 q1 = obj.Appendp(q, c.newprog)
 572                                 q1.Pos = p.Pos
 573                                 q1.As = AMOVD
 574                                 q1.From.Type = obj.TYPE_REG
 575                                 q1.From.Reg = REGTMP
 576                                 q1.To.Type = obj.TYPE_REG
 577                                 q1.To.Reg = REGSP
 578                                 q1.Spadj = c.autosize
 579
 580                                 if buildcfg.GOOS == "ios" {
 581                                         // iOS does not support SA_ONSTACK. We will run the signal handler
 582                                         // on the G stack. If we write below SP, it may be clobbered by
 583                                         // the signal handler. So we save LR after decrementing SP.
 584                                         q1 = obj.Appendp(q1, c.newprog)
 585                                         q1.Pos = p.Pos
 586                                         q1.As = AMOVD
 587                                         q1.From.Type = obj.TYPE_REG
 588                                         q1.From.Reg = REGLINK
 589                                         q1.To.Type = obj.TYPE_MEM
 590                                         q1.To.Reg = REGSP
 591                                 }
 592
 593                                 q1 = c.ctxt.EndUnsafePoint(q1, c.newprog, -1)
 594                         } else {
 595                                 // small frame, update SP and save LR in a single MOVD.W instruction
 596                                 q1 = obj.Appendp(q, c.newprog)
 597                                 q1.As = AMOVD
 598                                 q1.Pos = p.Pos
 599                                 q1.From.Type = obj.TYPE_REG
 600                                 q1.From.Reg = REGLINK
 601                                 q1.To.Type = obj.TYPE_MEM
 602                                 q1.Scond = C_XPRE
 603                                 q1.To.Offset = int64(-aoffset)
 604                                 q1.To.Reg = REGSP
 605                                 q1.Spadj = aoffset
 606
 607                                 prologueEnd = q1
 608                         }
 609
 610                         prologueEnd.Pos = prologueEnd.Pos.WithXlogue(src.PosPrologueEnd)
 611
 612                         // Frame pointer.
 613                         q1 = obj.Appendp(q1, c.newprog)
 614                         q1.Pos = p.Pos
 615                         q1.As = AMOVD
 616                         q1.From.Type = obj.TYPE_REG
 617                         q1.From.Reg = REGFP
 618                         q1.To.Type = obj.TYPE_MEM
 619                         q1.To.Reg = REGSP
 620                         q1.To.Offset = -8
 621
 622                         q1 = obj.Appendp(q1, c.newprog)
 623                         q1.Pos = p.Pos
 624                         q1.As = ASUB
 625                         q1.From.Type = obj.TYPE_CONST
 626                         q1.From.Offset = 8
 627                         q1.Reg = REGSP
 628                         q1.To.Type = obj.TYPE_REG
 629                         q1.To.Reg = REGFP
 630
 631                         if c.cursym.Func().Text.From.Sym.Wrapper() {
 632                                 // if(g->panic != nil && g->panic->argp == FP) g->panic->argp = bottom-of-frame
 633                                 //
 634                                 //      MOV  g_panic(g), R1
 635                                 //      CBNZ checkargp
 636                                 // end:
 637                                 //      NOP
 638                                 // ... function body ...
 639                                 // checkargp:
 640                                 //      MOV  panic_argp(R1), R2
 641                                 //      ADD  $(autosize+8), RSP, R3
 642                                 //      CMP  R2, R3
 643                                 //      BNE  end
 644                                 //      ADD  $8, RSP, R4
 645                                 //      MOVD R4, panic_argp(R1)
 646                                 //      B    end
 647                                 //
 648                                 // The NOP is needed to give the jumps somewhere to land.
 649                                 // It is a liblink NOP, not an ARM64 NOP: it encodes to 0 instruction bytes.
 650                                 q = q1
 651
 652                                 // MOV g_panic(g), R1
 653                                 q = obj.Appendp(q, c.newprog)
 654                                 q.As = AMOVD
 655                                 q.From.Type = obj.TYPE_MEM
 656                                 q.From.Reg = REGG
 657                                 q.From.Offset = 4 * int64(c.ctxt.Arch.PtrSize) // G.panic
 658                                 q.To.Type = obj.TYPE_REG
 659                                 q.To.Reg = REG_R1
 660
 661                                 // CBNZ R1, checkargp
 662                                 cbnz := obj.Appendp(q, c.newprog)
 663                                 cbnz.As = ACBNZ
 664                                 cbnz.From.Type = obj.TYPE_REG
 665                                 cbnz.From.Reg = REG_R1
 666                                 cbnz.To.Type = obj.TYPE_BRANCH
 667
 668                                 // Empty branch target at the top of the function body
 669                                 end := obj.Appendp(cbnz, c.newprog)
 670                                 end.As = obj.ANOP
 671
 672                                 // find the end of the function
 673                                 var last *obj.Prog
 674                                 for last = end; last.Link != nil; last = last.Link {
 675                                 }
 676
 677                                 // MOV panic_argp(R1), R2
 678                                 mov := obj.Appendp(last, c.newprog)
 679                                 mov.As = AMOVD
 680                                 mov.From.Type = obj.TYPE_MEM
 681                                 mov.From.Reg = REG_R1
 682                                 mov.From.Offset = 0 // Panic.argp
 683                                 mov.To.Type = obj.TYPE_REG
 684                                 mov.To.Reg = REG_R2
 685
 686                                 // CBNZ branches to the MOV above
 687                                 cbnz.To.SetTarget(mov)
 688
 689                                 // ADD $(autosize+8), SP, R3
 690                                 q = obj.Appendp(mov, c.newprog)
 691                                 q.As = AADD
 692                                 q.From.Type = obj.TYPE_CONST
 693                                 q.From.Offset = int64(c.autosize) + 8
 694                                 q.Reg = REGSP
 695                                 q.To.Type = obj.TYPE_REG
 696                                 q.To.Reg = REG_R3
 697
 698                                 // CMP R2, R3
 699                                 q = obj.Appendp(q, c.newprog)
 700                                 q.As = ACMP
 701                                 q.From.Type = obj.TYPE_REG
 702                                 q.From.Reg = REG_R2
 703                                 q.Reg = REG_R3
 704
 705                                 // BNE end
 706                                 q = obj.Appendp(q, c.newprog)
 707                                 q.As = ABNE
 708                                 q.To.Type = obj.TYPE_BRANCH
 709                                 q.To.SetTarget(end)
 710
 711                                 // ADD $8, SP, R4
 712                                 q = obj.Appendp(q, c.newprog)
 713                                 q.As = AADD
 714                                 q.From.Type = obj.TYPE_CONST
 715                                 q.From.Offset = 8
 716                                 q.Reg = REGSP
 717                                 q.To.Type = obj.TYPE_REG
 718                                 q.To.Reg = REG_R4
 719
 720                                 // MOV R4, panic_argp(R1)
 721                                 q = obj.Appendp(q, c.newprog)
 722                                 q.As = AMOVD
 723                                 q.From.Type = obj.TYPE_REG
 724                                 q.From.Reg = REG_R4
 725                                 q.To.Type = obj.TYPE_MEM
 726                                 q.To.Reg = REG_R1
 727                                 q.To.Offset = 0 // Panic.argp
 728
 729                                 // B end
 730                                 q = obj.Appendp(q, c.newprog)
 731                                 q.As = AB
 732                                 q.To.Type = obj.TYPE_BRANCH
 733                                 q.To.SetTarget(end)
 734                         }
 735
 736                 case obj.ARET:
 737                         nocache(p)
 738                         if p.From.Type == obj.TYPE_CONST {
 739                                 c.ctxt.Diag("using BECOME (%v) is not supported!", p)
 740                                 break
 741                         }
 742
 743                         retjmp = p.To.Sym
 744                         p.To = obj.Addr{}
 745                         if c.cursym.Func().Text.Mark&LEAF != 0 {
 746                                 if c.autosize != 0 {
 747                                         p.As = AADD
 748                                         p.From.Type = obj.TYPE_CONST
 749                                         p.From.Offset = int64(c.autosize)
 750                                         p.To.Type = obj.TYPE_REG
 751                                         p.To.Reg = REGSP
 752                                         p.Spadj = -c.autosize
 753
 754                                         // Frame pointer.
 755                                         p = obj.Appendp(p, c.newprog)
 756                                         p.As = ASUB
 757                                         p.From.Type = obj.TYPE_CONST
 758                                         p.From.Offset = 8
 759                                         p.Reg = REGSP
 760                                         p.To.Type = obj.TYPE_REG
 761                                         p.To.Reg = REGFP
 762                                 }
 763                         } else {
 764                                 /* want write-back pre-indexed SP+autosize -> SP, loading REGLINK*/
 765
 766                                 // Frame pointer.
 767                                 p.As = AMOVD
 768                                 p.From.Type = obj.TYPE_MEM
 769                                 p.From.Reg = REGSP
 770                                 p.From.Offset = -8
 771                                 p.To.Type = obj.TYPE_REG
 772                                 p.To.Reg = REGFP
 773                                 p = obj.Appendp(p, c.newprog)
 774
 775                                 aoffset := c.autosize
 776
 777                                 if aoffset <= 0xF0 {
 778                                         p.As = AMOVD
 779                                         p.From.Type = obj.TYPE_MEM
 780                                         p.Scond = C_XPOST
 781                                         p.From.Offset = int64(aoffset)
 782                                         p.From.Reg = REGSP
 783                                         p.To.Type = obj.TYPE_REG
 784                                         p.To.Reg = REGLINK
 785                                         p.Spadj = -aoffset
 786                                 } else {
 787                                         p.As = AMOVD
 788                                         p.From.Type = obj.TYPE_MEM
 789                                         p.From.Offset = 0
 790                                         p.From.Reg = REGSP
 791                                         p.To.Type = obj.TYPE_REG
 792                                         p.To.Reg = REGLINK
 793
 794                                         q = newprog()
 795                                         q.As = AADD
 796                                         q.From.Type = obj.TYPE_CONST
 797                                         q.From.Offset = int64(aoffset)
 798                                         q.To.Type = obj.TYPE_REG
 799                                         q.To.Reg = REGSP
 800                                         q.Link = p.Link
 801                                         q.Spadj = int32(-q.From.Offset)
 802                                         q.Pos = p.Pos
 803                                         p.Link = q
 804                                         p = q
 805                                 }
 806                         }
 807
 808                         // If enabled, this code emits 'MOV PC, R27' before every 'MOV LR, PC',
 809                         // so that if you are debugging a low-level crash where PC and LR are zero,
 810                         // you can look at R27 to see what jumped to the zero.
 811                         // This is useful when bringing up Go on a new system.
 812                         // (There is similar code in ../ppc64/obj9.go:/if.false.)
 813                         const debugRETZERO = false
 814                         if debugRETZERO {
 815                                 if p.As != obj.ARET {
 816                                         q = newprog()
 817                                         q.Pos = p.Pos
 818                                         q.Link = p.Link
 819                                         p.Link = q
 820                                         p = q
 821                                 }
 822                                 p.As = AADR
 823                                 p.From.Type = obj.TYPE_BRANCH
 824                                 p.From.Offset = 0
 825                                 p.To.Type = obj.TYPE_REG
 826                                 p.To.Reg = REGTMP
 827
 828                         }
 829
 830                         if p.As != obj.ARET {
 831                                 q = newprog()
 832                                 q.Pos = p.Pos
 833                                 q.Link = p.Link
 834                                 p.Link = q
 835                                 p = q
 836                         }
 837
 838                         if retjmp != nil { // retjmp
 839                                 p.As = AB
 840                                 p.To.Type = obj.TYPE_BRANCH
 841                                 p.To.Sym = retjmp
 842                                 p.Spadj = +c.autosize
 843                                 break
 844                         }
 845
 846                         p.As = obj.ARET
 847                         p.To.Type = obj.TYPE_MEM
 848                         p.To.Offset = 0
 849                         p.To.Reg = REGLINK
 850                         p.Spadj = +c.autosize
 851
 852                 case AADD, ASUB:
 853                         if p.To.Type == obj.TYPE_REG && p.To.Reg == REGSP && p.From.Type == obj.TYPE_CONST {
 854                                 if p.As == AADD {
 855                                         p.Spadj = int32(-p.From.Offset)
 856                                 } else {
 857                                         p.Spadj = int32(+p.From.Offset)
 858                                 }
 859                         }
 860
 861                 case obj.AGETCALLERPC:
 862                         if cursym.Leaf() {
 863                                 /* MOVD LR, Rd */
 864                                 p.As = AMOVD
 865                                 p.From.Type = obj.TYPE_REG
 866                                 p.From.Reg = REGLINK
 867                         } else {
 868                                 /* MOVD (RSP), Rd */
 869                                 p.As = AMOVD
 870                                 p.From.Type = obj.TYPE_MEM
 871                                 p.From.Reg = REGSP
 872                         }
 873
 874                 case obj.ADUFFCOPY:
 875                         //  ADR ret_addr, R27
 876                         //  STP (FP, R27), -24(SP)
 877                         //  SUB 24, SP, FP
 878                         //  DUFFCOPY
 879                         // ret_addr:
 880                         //  SUB 8, SP, FP
 881
 882                         q1 := p
 883                         // copy DUFFCOPY from q1 to q4
 884                         q4 := obj.Appendp(p, c.newprog)
 885                         q4.Pos = p.Pos
 886                         q4.As = obj.ADUFFCOPY
 887                         q4.To = p.To
 888
 889                         q1.As = AADR
 890                         q1.From.Type = obj.TYPE_BRANCH
 891                         q1.To.Type = obj.TYPE_REG
 892                         q1.To.Reg = REG_R27
 893
 894                         q2 := obj.Appendp(q1, c.newprog)
 895                         q2.Pos = p.Pos
 896                         q2.As = ASTP
 897                         q2.From.Type = obj.TYPE_REGREG
 898                         q2.From.Reg = REGFP
 899                         q2.From.Offset = int64(REG_R27)
 900                         q2.To.Type = obj.TYPE_MEM
 901                         q2.To.Reg = REGSP
 902                         q2.To.Offset = -24
 903
 904                         // maintain FP for DUFFCOPY
 905                         q3 := obj.Appendp(q2, c.newprog)
 906                         q3.Pos = p.Pos
 907                         q3.As = ASUB
 908                         q3.From.Type = obj.TYPE_CONST
 909                         q3.From.Offset = 24
 910                         q3.Reg = REGSP
 911                         q3.To.Type = obj.TYPE_REG
 912                         q3.To.Reg = REGFP
 913
 914                         q5 := obj.Appendp(q4, c.newprog)
 915                         q5.Pos = p.Pos
 916                         q5.As = ASUB
 917                         q5.From.Type = obj.TYPE_CONST
 918                         q5.From.Offset = 8
 919                         q5.Reg = REGSP
 920                         q5.To.Type = obj.TYPE_REG
 921                         q5.To.Reg = REGFP
 922                         q1.From.SetTarget(q5)
 923                         p = q5
 924
 925                 case obj.ADUFFZERO:
 926                         //  ADR ret_addr, R27
 927                         //  STP (FP, R27), -24(SP)
 928                         //  SUB 24, SP, FP
 929                         //  DUFFZERO
 930                         // ret_addr:
 931                         //  SUB 8, SP, FP
 932
 933                         q1 := p
 934                         // copy DUFFZERO from q1 to q4
 935                         q4 := obj.Appendp(p, c.newprog)
 936                         q4.Pos = p.Pos
 937                         q4.As = obj.ADUFFZERO
 938                         q4.To = p.To
 939
 940                         q1.As = AADR
 941                         q1.From.Type = obj.TYPE_BRANCH
 942                         q1.To.Type = obj.TYPE_REG
 943                         q1.To.Reg = REG_R27
 944
 945                         q2 := obj.Appendp(q1, c.newprog)
 946                         q2.Pos = p.Pos
 947                         q2.As = ASTP
 948                         q2.From.Type = obj.TYPE_REGREG
 949                         q2.From.Reg = REGFP
 950                         q2.From.Offset = int64(REG_R27)
 951                         q2.To.Type = obj.TYPE_MEM
 952                         q2.To.Reg = REGSP
 953                         q2.To.Offset = -24
 954
 955                         // maintain FP for DUFFZERO
 956                         q3 := obj.Appendp(q2, c.newprog)
 957                         q3.Pos = p.Pos
 958                         q3.As = ASUB
 959                         q3.From.Type = obj.TYPE_CONST
 960                         q3.From.Offset = 24
 961                         q3.Reg = REGSP
 962                         q3.To.Type = obj.TYPE_REG
 963                         q3.To.Reg = REGFP
 964
 965                         q5 := obj.Appendp(q4, c.newprog)
 966                         q5.Pos = p.Pos
 967                         q5.As = ASUB
 968                         q5.From.Type = obj.TYPE_CONST
 969                         q5.From.Offset = 8
 970                         q5.Reg = REGSP
 971                         q5.To.Type = obj.TYPE_REG
 972                         q5.To.Reg = REGFP
 973                         q1.From.SetTarget(q5)
 974                         p = q5
 975                 }
 976
 977                 if p.To.Type == obj.TYPE_REG && p.To.Reg == REGSP && p.Spadj == 0 {
 978                         f := c.cursym.Func()
 979                         if f.FuncFlag&objabi.FuncFlag_SPWRITE == 0 {
 980                                 c.cursym.Func().FuncFlag |= objabi.FuncFlag_SPWRITE
 981                                 if ctxt.Debugvlog || !ctxt.IsAsm {
 982                                         ctxt.Logf("auto-SPWRITE: %s %v\n", c.cursym.Name, p)
 983                                         if !ctxt.IsAsm {
 984                                                 ctxt.Diag("invalid auto-SPWRITE in non-assembly")
 985                                                 ctxt.DiagFlush()
 986                                                 log.Fatalf("bad SPWRITE")
 987                                         }
 988                                 }
 989                         }
 990                 }
 991         }
 992 }
 993
 994 func nocache(p *obj.Prog) {
 995         p.Optab = 0
 996         p.From.Class = 0
 997         p.To.Class = 0
 998 }
 999
1000 var unaryDst = map[obj.As]bool{
1001         AWORD:  true,
1002         ADWORD: true,
1003         ABL:    true,
1004         AB:     true,
1005         ACLREX: true,
1006 }
1007
1008 var Linkarm64 = obj.LinkArch{
1009         Arch:           sys.ArchARM64,
1010         Init:           buildop,
1011         Preprocess:     preprocess,
1012         Assemble:       span7,
1013         Progedit:       progedit,
1014         UnaryDst:       unaryDst,
1015         DWARFRegisters: ARM64DWARFRegisters,
1016 }