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 // zrReplace is the set of instructions for which $0 in the From operand
  55 // should be replaced with REGZERO.
  56 var zrReplace = map[obj.As]bool{
  57         AMOVD:  true,
  58         AMOVW:  true,
  59         AMOVWU: true,
  60         AMOVH:  true,
  61         AMOVHU: true,
  62         AMOVB:  true,
  63         AMOVBU: true,
  64         ASBC:   true,
  65         ASBCW:  true,
  66         ASBCS:  true,
  67         ASBCSW: true,
  68         AADC:   true,
  69         AADCW:  true,
  70         AADCS:  true,
  71         AADCSW: true,
  72         AFMOVD: true,
  73         AFMOVS: true,
  74 }
  75
  76 func (c *ctxt7) stacksplit(p *obj.Prog, framesize int32) *obj.Prog {
  77         if c.ctxt.Flag_maymorestack != "" {
  78                 p = c.cursym.Func().SpillRegisterArgs(p, c.newprog)
  79
  80                 // Save LR and make room for FP, REGCTXT. Leave room
  81                 // for caller's saved FP.
  82                 const frameSize = 32
  83                 p = obj.Appendp(p, c.newprog)
  84                 p.As = AMOVD
  85                 p.From.Type = obj.TYPE_REG
  86                 p.From.Reg = REGLINK
  87                 p.To.Type = obj.TYPE_MEM
  88                 p.Scond = C_XPRE
  89                 p.To.Offset = -frameSize
  90                 p.To.Reg = REGSP
  91                 p.Spadj = frameSize
  92
  93                 // Save FP.
  94                 p = obj.Appendp(p, c.newprog)
  95                 p.As = AMOVD
  96                 p.From.Type = obj.TYPE_REG
  97                 p.From.Reg = REGFP
  98                 p.To.Type = obj.TYPE_MEM
  99                 p.To.Reg = REGSP
 100                 p.To.Offset = -8
 101
 102                 p = obj.Appendp(p, c.newprog)
 103                 p.As = ASUB
 104                 p.From.Type = obj.TYPE_CONST
 105                 p.From.Offset = 8
 106                 p.Reg = REGSP
 107                 p.To.Type = obj.TYPE_REG
 108                 p.To.Reg = REGFP
 109
 110                 // Save REGCTXT (for simplicity we do this whether or
 111                 // not we need it.)
 112                 p = obj.Appendp(p, c.newprog)
 113                 p.As = AMOVD
 114                 p.From.Type = obj.TYPE_REG
 115                 p.From.Reg = REGCTXT
 116                 p.To.Type = obj.TYPE_MEM
 117                 p.To.Reg = REGSP
 118                 p.To.Offset = 8
 119
 120                 // BL maymorestack
 121                 p = obj.Appendp(p, c.newprog)
 122                 p.As = ABL
 123                 p.To.Type = obj.TYPE_BRANCH
 124                 // See ../x86/obj6.go
 125                 p.To.Sym = c.ctxt.LookupABI(c.ctxt.Flag_maymorestack, c.cursym.ABI())
 126
 127                 // Restore REGCTXT.
 128                 p = obj.Appendp(p, c.newprog)
 129                 p.As = AMOVD
 130                 p.From.Type = obj.TYPE_MEM
 131                 p.From.Reg = REGSP
 132                 p.From.Offset = 8
 133                 p.To.Type = obj.TYPE_REG
 134                 p.To.Reg = REGCTXT
 135
 136                 // Restore FP.
 137                 p = obj.Appendp(p, c.newprog)
 138                 p.As = AMOVD
 139                 p.From.Type = obj.TYPE_MEM
 140                 p.From.Reg = REGSP
 141                 p.From.Offset = -8
 142                 p.To.Type = obj.TYPE_REG
 143                 p.To.Reg = REGFP
 144
 145                 // Restore LR and SP.
 146                 p = obj.Appendp(p, c.newprog)
 147                 p.As = AMOVD
 148                 p.From.Type = obj.TYPE_MEM
 149                 p.Scond = C_XPOST
 150                 p.From.Offset = frameSize
 151                 p.From.Reg = REGSP
 152                 p.To.Type = obj.TYPE_REG
 153                 p.To.Reg = REGLINK
 154                 p.Spadj = -frameSize
 155
 156                 p = c.cursym.Func().UnspillRegisterArgs(p, c.newprog)
 157         }
 158
 159         // Jump back to here after morestack returns.
 160         startPred := p
 161
 162         // MOV  g_stackguard(g), RT1
 163         p = obj.Appendp(p, c.newprog)
 164
 165         p.As = AMOVD
 166         p.From.Type = obj.TYPE_MEM
 167         p.From.Reg = REGG
 168         p.From.Offset = 2 * int64(c.ctxt.Arch.PtrSize) // G.stackguard0
 169         if c.cursym.CFunc() {
 170                 p.From.Offset = 3 * int64(c.ctxt.Arch.PtrSize) // G.stackguard1
 171         }
 172         p.To.Type = obj.TYPE_REG
 173         p.To.Reg = REGRT1
 174
 175         // Mark the stack bound check and morestack call async nonpreemptible.
 176         // If we get preempted here, when resumed the preemption request is
 177         // cleared, but we'll still call morestack, which will double the stack
 178         // unnecessarily. See issue #35470.
 179         p = c.ctxt.StartUnsafePoint(p, c.newprog)
 180
 181         q := (*obj.Prog)(nil)
 182         if framesize <= objabi.StackSmall {
 183                 // small stack: SP < stackguard
 184                 //      CMP     stackguard, SP
 185
 186                 p = obj.Appendp(p, c.newprog)
 187                 p.As = ACMP
 188                 p.From.Type = obj.TYPE_REG
 189                 p.From.Reg = REGRT1
 190                 p.Reg = REGSP
 191         } else if framesize <= objabi.StackBig {
 192                 // large stack: SP-framesize < stackguard-StackSmall
 193                 //      SUB     $(framesize-StackSmall), SP, RT2
 194                 //      CMP     stackguard, RT2
 195                 p = obj.Appendp(p, c.newprog)
 196
 197                 p.As = ASUB
 198                 p.From.Type = obj.TYPE_CONST
 199                 p.From.Offset = int64(framesize) - objabi.StackSmall
 200                 p.Reg = REGSP
 201                 p.To.Type = obj.TYPE_REG
 202                 p.To.Reg = REGRT2
 203
 204                 p = obj.Appendp(p, c.newprog)
 205                 p.As = ACMP
 206                 p.From.Type = obj.TYPE_REG
 207                 p.From.Reg = REGRT1
 208                 p.Reg = REGRT2
 209         } else {
 210                 // Such a large stack we need to protect against underflow.
 211                 // The runtime guarantees SP > objabi.StackBig, but
 212                 // framesize is large enough that SP-framesize may
 213                 // underflow, causing a direct comparison with the
 214                 // stack guard to incorrectly succeed. We explicitly
 215                 // guard against underflow.
 216                 //
 217                 //      SUBS    $(framesize-StackSmall), SP, RT2
 218                 //      // On underflow, jump to morestack
 219                 //      BLO     label_of_call_to_morestack
 220                 //      CMP     stackguard, RT2
 221
 222                 p = obj.Appendp(p, c.newprog)
 223                 p.As = ASUBS
 224                 p.From.Type = obj.TYPE_CONST
 225                 p.From.Offset = int64(framesize) - objabi.StackSmall
 226                 p.Reg = REGSP
 227                 p.To.Type = obj.TYPE_REG
 228                 p.To.Reg = REGRT2
 229
 230                 p = obj.Appendp(p, c.newprog)
 231                 q = p
 232                 p.As = ABLO
 233                 p.To.Type = obj.TYPE_BRANCH
 234
 235                 p = obj.Appendp(p, c.newprog)
 236                 p.As = ACMP
 237                 p.From.Type = obj.TYPE_REG
 238                 p.From.Reg = REGRT1
 239                 p.Reg = REGRT2
 240         }
 241
 242         // BLS  do-morestack
 243         bls := obj.Appendp(p, c.newprog)
 244         bls.As = ABLS
 245         bls.To.Type = obj.TYPE_BRANCH
 246
 247         end := c.ctxt.EndUnsafePoint(bls, c.newprog, -1)
 248
 249         var last *obj.Prog
 250         for last = c.cursym.Func().Text; last.Link != nil; last = last.Link {
 251         }
 252
 253         // Now we are at the end of the function, but logically
 254         // we are still in function prologue. We need to fix the
 255         // SP data and PCDATA.
 256         spfix := obj.Appendp(last, c.newprog)
 257         spfix.As = obj.ANOP
 258         spfix.Spadj = -framesize
 259
 260         pcdata := c.ctxt.EmitEntryStackMap(c.cursym, spfix, c.newprog)
 261         pcdata = c.ctxt.StartUnsafePoint(pcdata, c.newprog)
 262
 263         if q != nil {
 264                 q.To.SetTarget(pcdata)
 265         }
 266         bls.To.SetTarget(pcdata)
 267
 268         spill := c.cursym.Func().SpillRegisterArgs(pcdata, c.newprog)
 269
 270         // MOV  LR, R3
 271         movlr := obj.Appendp(spill, c.newprog)
 272         movlr.As = AMOVD
 273         movlr.From.Type = obj.TYPE_REG
 274         movlr.From.Reg = REGLINK
 275         movlr.To.Type = obj.TYPE_REG
 276         movlr.To.Reg = REG_R3
 277
 278         debug := movlr
 279         if false {
 280                 debug = obj.Appendp(debug, c.newprog)
 281                 debug.As = AMOVD
 282                 debug.From.Type = obj.TYPE_CONST
 283                 debug.From.Offset = int64(framesize)
 284                 debug.To.Type = obj.TYPE_REG
 285                 debug.To.Reg = REGTMP
 286         }
 287
 288         // BL   runtime.morestack(SB)
 289         call := obj.Appendp(debug, c.newprog)
 290         call.As = ABL
 291         call.To.Type = obj.TYPE_BRANCH
 292         morestack := "runtime.morestack"
 293         switch {
 294         case c.cursym.CFunc():
 295                 morestack = "runtime.morestackc"
 296         case !c.cursym.Func().Text.From.Sym.NeedCtxt():
 297                 morestack = "runtime.morestack_noctxt"
 298         }
 299         call.To.Sym = c.ctxt.Lookup(morestack)
 300
 301         unspill := c.cursym.Func().UnspillRegisterArgs(call, c.newprog)
 302         pcdata = c.ctxt.EndUnsafePoint(unspill, c.newprog, -1)
 303
 304         // B    start
 305         jmp := obj.Appendp(pcdata, c.newprog)
 306         jmp.As = AB
 307         jmp.To.Type = obj.TYPE_BRANCH
 308         jmp.To.SetTarget(startPred.Link)
 309         jmp.Spadj = +framesize
 310
 311         return end
 312 }
 313
 314 func progedit(ctxt *obj.Link, p *obj.Prog, newprog obj.ProgAlloc) {
 315         c := ctxt7{ctxt: ctxt, newprog: newprog}
 316
 317         p.From.Class = 0
 318         p.To.Class = 0
 319
 320         // Previously we rewrote $0 to ZR, but we have now removed this change.
 321         // In order to be compatible with some previous legal instruction formats,
 322         // reserve the previous conversion for some specific instructions.
 323         if p.From.Type == obj.TYPE_CONST && p.From.Offset == 0 && zrReplace[p.As] {
 324                 p.From.Type = obj.TYPE_REG
 325                 p.From.Reg = REGZERO
 326         }
 327
 328         // Rewrite BR/BL to symbol as TYPE_BRANCH.
 329         switch p.As {
 330         case AB,
 331                 ABL,
 332                 obj.ARET,
 333                 obj.ADUFFZERO,
 334                 obj.ADUFFCOPY:
 335                 if p.To.Sym != nil {
 336                         p.To.Type = obj.TYPE_BRANCH
 337                 }
 338                 break
 339         }
 340
 341         // Rewrite float constants to values stored in memory.
 342         switch p.As {
 343         case AFMOVS:
 344                 if p.From.Type == obj.TYPE_FCONST {
 345                         f64 := p.From.Val.(float64)
 346                         f32 := float32(f64)
 347                         if c.chipfloat7(f64) > 0 {
 348                                 break
 349                         }
 350                         if math.Float32bits(f32) == 0 {
 351                                 p.From.Type = obj.TYPE_REG
 352                                 p.From.Reg = REGZERO
 353                                 break
 354                         }
 355                         p.From.Type = obj.TYPE_MEM
 356                         p.From.Sym = c.ctxt.Float32Sym(f32)
 357                         p.From.Name = obj.NAME_EXTERN
 358                         p.From.Offset = 0
 359                 }
 360
 361         case AFMOVD:
 362                 if p.From.Type == obj.TYPE_FCONST {
 363                         f64 := p.From.Val.(float64)
 364                         if c.chipfloat7(f64) > 0 {
 365                                 break
 366                         }
 367                         if math.Float64bits(f64) == 0 {
 368                                 p.From.Type = obj.TYPE_REG
 369                                 p.From.Reg = REGZERO
 370                                 break
 371                         }
 372                         p.From.Type = obj.TYPE_MEM
 373                         p.From.Sym = c.ctxt.Float64Sym(f64)
 374                         p.From.Name = obj.NAME_EXTERN
 375                         p.From.Offset = 0
 376                 }
 377
 378                 break
 379         }
 380
 381         // Rewrite negative immediates as positive immediates with
 382         // complementary instruction.
 383         switch p.As {
 384         case AADD, ASUB, ACMP, ACMN:
 385                 if p.From.Type == obj.TYPE_CONST && p.From.Offset < 0 && p.From.Offset != -1<<63 {
 386                         p.From.Offset = -p.From.Offset
 387                         p.As = complements[p.As]
 388                 }
 389         case AADDW, ASUBW, ACMPW, ACMNW:
 390                 if p.From.Type == obj.TYPE_CONST && p.From.Offset < 0 && int32(p.From.Offset) != -1<<31 {
 391                         p.From.Offset = -p.From.Offset
 392                         p.As = complements[p.As]
 393                 }
 394         }
 395
 396         if c.ctxt.Flag_dynlink {
 397                 c.rewriteToUseGot(p)
 398         }
 399 }
 400
 401 // Rewrite p, if necessary, to access global data via the global offset table.
 402 func (c *ctxt7) rewriteToUseGot(p *obj.Prog) {
 403         if p.As == obj.ADUFFCOPY || p.As == obj.ADUFFZERO {
 404                 //     ADUFFxxx $offset
 405                 // becomes
 406                 //     MOVD runtime.duffxxx@GOT, REGTMP
 407                 //     ADD $offset, REGTMP
 408                 //     CALL REGTMP
 409                 var sym *obj.LSym
 410                 if p.As == obj.ADUFFZERO {
 411                         sym = c.ctxt.LookupABI("runtime.duffzero", obj.ABIInternal)
 412                 } else {
 413                         sym = c.ctxt.LookupABI("runtime.duffcopy", obj.ABIInternal)
 414                 }
 415                 offset := p.To.Offset
 416                 p.As = AMOVD
 417                 p.From.Type = obj.TYPE_MEM
 418                 p.From.Name = obj.NAME_GOTREF
 419                 p.From.Sym = sym
 420                 p.To.Type = obj.TYPE_REG
 421                 p.To.Reg = REGTMP
 422                 p.To.Name = obj.NAME_NONE
 423                 p.To.Offset = 0
 424                 p.To.Sym = nil
 425                 p1 := obj.Appendp(p, c.newprog)
 426                 p1.As = AADD
 427                 p1.From.Type = obj.TYPE_CONST
 428                 p1.From.Offset = offset
 429                 p1.To.Type = obj.TYPE_REG
 430                 p1.To.Reg = REGTMP
 431                 p2 := obj.Appendp(p1, c.newprog)
 432                 p2.As = obj.ACALL
 433                 p2.To.Type = obj.TYPE_REG
 434                 p2.To.Reg = REGTMP
 435         }
 436
 437         // We only care about global data: NAME_EXTERN means a global
 438         // symbol in the Go sense, and p.Sym.Local is true for a few
 439         // internally defined symbols.
 440         if p.From.Type == obj.TYPE_ADDR && p.From.Name == obj.NAME_EXTERN && !p.From.Sym.Local() {
 441                 // MOVD $sym, Rx becomes MOVD sym@GOT, Rx
 442                 // MOVD $sym+<off>, Rx becomes MOVD sym@GOT, Rx; ADD <off>, Rx
 443                 if p.As != AMOVD {
 444                         c.ctxt.Diag("do not know how to handle TYPE_ADDR in %v with -dynlink", p)
 445                 }
 446                 if p.To.Type != obj.TYPE_REG {
 447                         c.ctxt.Diag("do not know how to handle LEAQ-type insn to non-register in %v with -dynlink", p)
 448                 }
 449                 p.From.Type = obj.TYPE_MEM
 450                 p.From.Name = obj.NAME_GOTREF
 451                 if p.From.Offset != 0 {
 452                         q := obj.Appendp(p, c.newprog)
 453                         q.As = AADD
 454                         q.From.Type = obj.TYPE_CONST
 455                         q.From.Offset = p.From.Offset
 456                         q.To = p.To
 457                         p.From.Offset = 0
 458                 }
 459         }
 460         if p.GetFrom3() != nil && p.GetFrom3().Name == obj.NAME_EXTERN {
 461                 c.ctxt.Diag("don't know how to handle %v with -dynlink", p)
 462         }
 463         var source *obj.Addr
 464         // MOVx sym, Ry becomes MOVD sym@GOT, REGTMP; MOVx (REGTMP), Ry
 465         // MOVx Ry, sym becomes MOVD sym@GOT, REGTMP; MOVD Ry, (REGTMP)
 466         // An addition may be inserted between the two MOVs if there is an offset.
 467         if p.From.Name == obj.NAME_EXTERN && !p.From.Sym.Local() {
 468                 if p.To.Name == obj.NAME_EXTERN && !p.To.Sym.Local() {
 469                         c.ctxt.Diag("cannot handle NAME_EXTERN on both sides in %v with -dynlink", p)
 470                 }
 471                 source = &p.From
 472         } else if p.To.Name == obj.NAME_EXTERN && !p.To.Sym.Local() {
 473                 source = &p.To
 474         } else {
 475                 return
 476         }
 477         if p.As == obj.ATEXT || p.As == obj.AFUNCDATA || p.As == obj.ACALL || p.As == obj.ARET || p.As == obj.AJMP {
 478                 return
 479         }
 480         if source.Sym.Type == objabi.STLSBSS {
 481                 return
 482         }
 483         if source.Type != obj.TYPE_MEM {
 484                 c.ctxt.Diag("don't know how to handle %v with -dynlink", p)
 485         }
 486         p1 := obj.Appendp(p, c.newprog)
 487         p2 := obj.Appendp(p1, c.newprog)
 488         p1.As = AMOVD
 489         p1.From.Type = obj.TYPE_MEM
 490         p1.From.Sym = source.Sym
 491         p1.From.Name = obj.NAME_GOTREF
 492         p1.To.Type = obj.TYPE_REG
 493         p1.To.Reg = REGTMP
 494
 495         p2.As = p.As
 496         p2.From = p.From
 497         p2.To = p.To
 498         if p.From.Name == obj.NAME_EXTERN {
 499                 p2.From.Reg = REGTMP
 500                 p2.From.Name = obj.NAME_NONE
 501                 p2.From.Sym = nil
 502         } else if p.To.Name == obj.NAME_EXTERN {
 503                 p2.To.Reg = REGTMP
 504                 p2.To.Name = obj.NAME_NONE
 505                 p2.To.Sym = nil
 506         } else {
 507                 return
 508         }
 509         obj.Nopout(p)
 510 }
 511
 512 func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
 513         if cursym.Func().Text == nil || cursym.Func().Text.Link == nil {
 514                 return
 515         }
 516
 517         c := ctxt7{ctxt: ctxt, newprog: newprog, cursym: cursym}
 518
 519         p := c.cursym.Func().Text
 520         textstksiz := p.To.Offset
 521         if textstksiz == -8 {
 522                 // Historical way to mark NOFRAME.
 523                 p.From.Sym.Set(obj.AttrNoFrame, true)
 524                 textstksiz = 0
 525         }
 526         if textstksiz < 0 {
 527                 c.ctxt.Diag("negative frame size %d - did you mean NOFRAME?", textstksiz)
 528         }
 529         if p.From.Sym.NoFrame() {
 530                 if textstksiz != 0 {
 531                         c.ctxt.Diag("NOFRAME functions must have a frame size of 0, not %d", textstksiz)
 532                 }
 533         }
 534
 535         c.cursym.Func().Args = p.To.Val.(int32)
 536         c.cursym.Func().Locals = int32(textstksiz)
 537
 538         /*
 539          * find leaf subroutines
 540          */
 541         for p := c.cursym.Func().Text; p != nil; p = p.Link {
 542                 switch p.As {
 543                 case obj.ATEXT:
 544                         p.Mark |= LEAF
 545
 546                 case ABL,
 547                         obj.ADUFFZERO,
 548                         obj.ADUFFCOPY:
 549                         c.cursym.Func().Text.Mark &^= LEAF
 550                 }
 551         }
 552
 553         var q *obj.Prog
 554         var q1 *obj.Prog
 555         var retjmp *obj.LSym
 556         for p := c.cursym.Func().Text; p != nil; p = p.Link {
 557                 o := p.As
 558                 switch o {
 559                 case obj.ATEXT:
 560                         c.cursym.Func().Text = p
 561                         c.autosize = int32(textstksiz)
 562
 563                         if p.Mark&LEAF != 0 && c.autosize == 0 {
 564                                 // A leaf function with no locals has no frame.
 565                                 p.From.Sym.Set(obj.AttrNoFrame, true)
 566                         }
 567
 568                         if !p.From.Sym.NoFrame() {
 569                                 // If there is a stack frame at all, it includes
 570                                 // space to save the LR.
 571                                 c.autosize += 8
 572                         }
 573
 574                         if c.autosize != 0 {
 575                                 extrasize := int32(0)
 576                                 if c.autosize%16 == 8 {
 577                                         // Allocate extra 8 bytes on the frame top to save FP
 578                                         extrasize = 8
 579                                 } else if c.autosize&(16-1) == 0 {
 580                                         // Allocate extra 16 bytes to save FP for the old frame whose size is 8 mod 16
 581                                         extrasize = 16
 582                                 } else {
 583                                         c.ctxt.Diag("%v: unaligned frame size %d - must be 16 aligned", p, c.autosize-8)
 584                                 }
 585                                 c.autosize += extrasize
 586                                 c.cursym.Func().Locals += extrasize
 587
 588                                 // low 32 bits for autosize
 589                                 // high 32 bits for extrasize
 590                                 p.To.Offset = int64(c.autosize) | int64(extrasize)<<32
 591                         } else {
 592                                 // NOFRAME
 593                                 p.To.Offset = 0
 594                         }
 595
 596                         if c.autosize == 0 && c.cursym.Func().Text.Mark&LEAF == 0 {
 597                                 if c.ctxt.Debugvlog {
 598                                         c.ctxt.Logf("save suppressed in: %s\n", c.cursym.Func().Text.From.Sym.Name)
 599                                 }
 600                                 c.cursym.Func().Text.Mark |= LEAF
 601                         }
 602
 603                         if cursym.Func().Text.Mark&LEAF != 0 {
 604                                 cursym.Set(obj.AttrLeaf, true)
 605                                 if p.From.Sym.NoFrame() {
 606                                         break
 607                                 }
 608                         }
 609
 610                         if p.Mark&LEAF != 0 && c.autosize < objabi.StackSmall {
 611                                 // A leaf function with a small stack can be marked
 612                                 // NOSPLIT, avoiding a stack check.
 613                                 p.From.Sym.Set(obj.AttrNoSplit, true)
 614                         }
 615
 616                         if !p.From.Sym.NoSplit() {
 617                                 p = c.stacksplit(p, c.autosize) // emit split check
 618                         }
 619
 620                         var prologueEnd *obj.Prog
 621
 622                         aoffset := c.autosize
 623                         if aoffset > 0xf0 {
 624                                 // MOVD.W offset variant range is -0x100 to 0xf8, SP should be 16-byte aligned.
 625                                 // so the maximum aoffset value is 0xf0.
 626                                 aoffset = 0xf0
 627                         }
 628
 629                         // Frame is non-empty. Make sure to save link register, even if
 630                         // it is a leaf function, so that traceback works.
 631                         q = p
 632                         if c.autosize > aoffset {
 633                                 // Frame size is too large for a MOVD.W instruction. Store the frame pointer
 634                                 // register and link register before decrementing SP, so if a signal comes
 635                                 // during the execution of the function prologue, the traceback code will
 636                                 // not see a half-updated stack frame.
 637
 638                                 // SUB $autosize, RSP, R20
 639                                 q1 = obj.Appendp(q, c.newprog)
 640                                 q1.Pos = p.Pos
 641                                 q1.As = ASUB
 642                                 q1.From.Type = obj.TYPE_CONST
 643                                 q1.From.Offset = int64(c.autosize)
 644                                 q1.Reg = REGSP
 645                                 q1.To.Type = obj.TYPE_REG
 646                                 q1.To.Reg = REG_R20
 647
 648                                 prologueEnd = q1
 649
 650                                 // STP (R29, R30), -8(R20)
 651                                 q1 = obj.Appendp(q1, c.newprog)
 652                                 q1.Pos = p.Pos
 653                                 q1.As = ASTP
 654                                 q1.From.Type = obj.TYPE_REGREG
 655                                 q1.From.Reg = REGFP
 656                                 q1.From.Offset = REGLINK
 657                                 q1.To.Type = obj.TYPE_MEM
 658                                 q1.To.Reg = REG_R20
 659                                 q1.To.Offset = -8
 660
 661                                 // This is not async preemptible, as if we open a frame
 662                                 // at the current SP, it will clobber the saved LR.
 663                                 q1 = c.ctxt.StartUnsafePoint(q1, c.newprog)
 664
 665                                 // MOVD R20, RSP
 666                                 q1 = obj.Appendp(q1, c.newprog)
 667                                 q1.Pos = p.Pos
 668                                 q1.As = AMOVD
 669                                 q1.From.Type = obj.TYPE_REG
 670                                 q1.From.Reg = REG_R20
 671                                 q1.To.Type = obj.TYPE_REG
 672                                 q1.To.Reg = REGSP
 673                                 q1.Spadj = c.autosize
 674
 675                                 q1 = c.ctxt.EndUnsafePoint(q1, c.newprog, -1)
 676
 677                                 if buildcfg.GOOS == "ios" {
 678                                         // iOS does not support SA_ONSTACK. We will run the signal handler
 679                                         // on the G stack. If we write below SP, it may be clobbered by
 680                                         // the signal handler. So we save FP and LR after decrementing SP.
 681                                         // STP (R29, R30), -8(RSP)
 682                                         q1 = obj.Appendp(q1, c.newprog)
 683                                         q1.Pos = p.Pos
 684                                         q1.As = ASTP
 685                                         q1.From.Type = obj.TYPE_REGREG
 686                                         q1.From.Reg = REGFP
 687                                         q1.From.Offset = REGLINK
 688                                         q1.To.Type = obj.TYPE_MEM
 689                                         q1.To.Reg = REGSP
 690                                         q1.To.Offset = -8
 691                                 }
 692                         } else {
 693                                 // small frame, update SP and save LR in a single MOVD.W instruction.
 694                                 // So if a signal comes during the execution of the function prologue,
 695                                 // the traceback code will not see a half-updated stack frame.
 696                                 // Also, on Linux, in a cgo binary we may get a SIGSETXID signal
 697                                 // early on before the signal stack is set, as glibc doesn't allow
 698                                 // us to block SIGSETXID. So it is important that we don't write below
 699                                 // the SP until the signal stack is set.
 700                                 // Luckily, all the functions from thread entry to setting the signal
 701                                 // stack have small frames.
 702                                 q1 = obj.Appendp(q, c.newprog)
 703                                 q1.As = AMOVD
 704                                 q1.Pos = p.Pos
 705                                 q1.From.Type = obj.TYPE_REG
 706                                 q1.From.Reg = REGLINK
 707                                 q1.To.Type = obj.TYPE_MEM
 708                                 q1.Scond = C_XPRE
 709                                 q1.To.Offset = int64(-aoffset)
 710                                 q1.To.Reg = REGSP
 711                                 q1.Spadj = aoffset
 712
 713                                 prologueEnd = q1
 714
 715                                 // Frame pointer.
 716                                 q1 = obj.Appendp(q1, c.newprog)
 717                                 q1.Pos = p.Pos
 718                                 q1.As = AMOVD
 719                                 q1.From.Type = obj.TYPE_REG
 720                                 q1.From.Reg = REGFP
 721                                 q1.To.Type = obj.TYPE_MEM
 722                                 q1.To.Reg = REGSP
 723                                 q1.To.Offset = -8
 724                         }
 725
 726                         prologueEnd.Pos = prologueEnd.Pos.WithXlogue(src.PosPrologueEnd)
 727
 728                         q1 = obj.Appendp(q1, c.newprog)
 729                         q1.Pos = p.Pos
 730                         q1.As = ASUB
 731                         q1.From.Type = obj.TYPE_CONST
 732                         q1.From.Offset = 8
 733                         q1.Reg = REGSP
 734                         q1.To.Type = obj.TYPE_REG
 735                         q1.To.Reg = REGFP
 736
 737                         if c.cursym.Func().Text.From.Sym.Wrapper() {
 738                                 // if(g->panic != nil && g->panic->argp == FP) g->panic->argp = bottom-of-frame
 739                                 //
 740                                 //      MOV  g_panic(g), RT1
 741                                 //      CBNZ checkargp
 742                                 // end:
 743                                 //      NOP
 744                                 // ... function body ...
 745                                 // checkargp:
 746                                 //      MOV  panic_argp(RT1), RT2
 747                                 //      ADD  $(autosize+8), RSP, R20
 748                                 //      CMP  RT2, R20
 749                                 //      BNE  end
 750                                 //      ADD  $8, RSP, R20
 751                                 //      MOVD R20, panic_argp(RT1)
 752                                 //      B    end
 753                                 //
 754                                 // The NOP is needed to give the jumps somewhere to land.
 755                                 // It is a liblink NOP, not an ARM64 NOP: it encodes to 0 instruction bytes.
 756                                 q = q1
 757
 758                                 // MOV g_panic(g), RT1
 759                                 q = obj.Appendp(q, c.newprog)
 760                                 q.As = AMOVD
 761                                 q.From.Type = obj.TYPE_MEM
 762                                 q.From.Reg = REGG
 763                                 q.From.Offset = 4 * int64(c.ctxt.Arch.PtrSize) // G.panic
 764                                 q.To.Type = obj.TYPE_REG
 765                                 q.To.Reg = REGRT1
 766
 767                                 // CBNZ RT1, checkargp
 768                                 cbnz := obj.Appendp(q, c.newprog)
 769                                 cbnz.As = ACBNZ
 770                                 cbnz.From.Type = obj.TYPE_REG
 771                                 cbnz.From.Reg = REGRT1
 772                                 cbnz.To.Type = obj.TYPE_BRANCH
 773
 774                                 // Empty branch target at the top of the function body
 775                                 end := obj.Appendp(cbnz, c.newprog)
 776                                 end.As = obj.ANOP
 777
 778                                 // find the end of the function
 779                                 var last *obj.Prog
 780                                 for last = end; last.Link != nil; last = last.Link {
 781                                 }
 782
 783                                 // MOV panic_argp(RT1), RT2
 784                                 mov := obj.Appendp(last, c.newprog)
 785                                 mov.As = AMOVD
 786                                 mov.From.Type = obj.TYPE_MEM
 787                                 mov.From.Reg = REGRT1
 788                                 mov.From.Offset = 0 // Panic.argp
 789                                 mov.To.Type = obj.TYPE_REG
 790                                 mov.To.Reg = REGRT2
 791
 792                                 // CBNZ branches to the MOV above
 793                                 cbnz.To.SetTarget(mov)
 794
 795                                 // ADD $(autosize+8), SP, R20
 796                                 q = obj.Appendp(mov, c.newprog)
 797                                 q.As = AADD
 798                                 q.From.Type = obj.TYPE_CONST
 799                                 q.From.Offset = int64(c.autosize) + 8
 800                                 q.Reg = REGSP
 801                                 q.To.Type = obj.TYPE_REG
 802                                 q.To.Reg = REG_R20
 803
 804                                 // CMP RT2, R20
 805                                 q = obj.Appendp(q, c.newprog)
 806                                 q.As = ACMP
 807                                 q.From.Type = obj.TYPE_REG
 808                                 q.From.Reg = REGRT2
 809                                 q.Reg = REG_R20
 810
 811                                 // BNE end
 812                                 q = obj.Appendp(q, c.newprog)
 813                                 q.As = ABNE
 814                                 q.To.Type = obj.TYPE_BRANCH
 815                                 q.To.SetTarget(end)
 816
 817                                 // ADD $8, SP, R20
 818                                 q = obj.Appendp(q, c.newprog)
 819                                 q.As = AADD
 820                                 q.From.Type = obj.TYPE_CONST
 821                                 q.From.Offset = 8
 822                                 q.Reg = REGSP
 823                                 q.To.Type = obj.TYPE_REG
 824                                 q.To.Reg = REG_R20
 825
 826                                 // MOV R20, panic_argp(RT1)
 827                                 q = obj.Appendp(q, c.newprog)
 828                                 q.As = AMOVD
 829                                 q.From.Type = obj.TYPE_REG
 830                                 q.From.Reg = REG_R20
 831                                 q.To.Type = obj.TYPE_MEM
 832                                 q.To.Reg = REGRT1
 833                                 q.To.Offset = 0 // Panic.argp
 834
 835                                 // B end
 836                                 q = obj.Appendp(q, c.newprog)
 837                                 q.As = AB
 838                                 q.To.Type = obj.TYPE_BRANCH
 839                                 q.To.SetTarget(end)
 840                         }
 841
 842                 case obj.ARET:
 843                         nocache(p)
 844                         if p.From.Type == obj.TYPE_CONST {
 845                                 c.ctxt.Diag("using BECOME (%v) is not supported!", p)
 846                                 break
 847                         }
 848
 849                         retjmp = p.To.Sym
 850                         p.To = obj.Addr{}
 851                         if c.cursym.Func().Text.Mark&LEAF != 0 {
 852                                 if c.autosize != 0 {
 853                                         p.As = AADD
 854                                         p.From.Type = obj.TYPE_CONST
 855                                         p.From.Offset = int64(c.autosize)
 856                                         p.To.Type = obj.TYPE_REG
 857                                         p.To.Reg = REGSP
 858                                         p.Spadj = -c.autosize
 859
 860                                         // Frame pointer.
 861                                         p = obj.Appendp(p, c.newprog)
 862                                         p.As = ASUB
 863                                         p.From.Type = obj.TYPE_CONST
 864                                         p.From.Offset = 8
 865                                         p.Reg = REGSP
 866                                         p.To.Type = obj.TYPE_REG
 867                                         p.To.Reg = REGFP
 868                                 }
 869                         } else {
 870                                 aoffset := c.autosize
 871                                 // LDP -8(RSP), (R29, R30)
 872                                 p.As = ALDP
 873                                 p.From.Type = obj.TYPE_MEM
 874                                 p.From.Offset = -8
 875                                 p.From.Reg = REGSP
 876                                 p.To.Type = obj.TYPE_REGREG
 877                                 p.To.Reg = REGFP
 878                                 p.To.Offset = REGLINK
 879
 880                                 // ADD $aoffset, RSP, RSP
 881                                 q = newprog()
 882                                 q.As = AADD
 883                                 q.From.Type = obj.TYPE_CONST
 884                                 q.From.Offset = int64(aoffset)
 885                                 q.To.Type = obj.TYPE_REG
 886                                 q.To.Reg = REGSP
 887                                 q.Spadj = -aoffset
 888                                 q.Pos = p.Pos
 889                                 q.Link = p.Link
 890                                 p.Link = q
 891                                 p = q
 892                         }
 893
 894                         // If enabled, this code emits 'MOV PC, R27' before every 'MOV LR, PC',
 895                         // so that if you are debugging a low-level crash where PC and LR are zero,
 896                         // you can look at R27 to see what jumped to the zero.
 897                         // This is useful when bringing up Go on a new system.
 898                         // (There is similar code in ../ppc64/obj9.go:/if.false.)
 899                         const debugRETZERO = false
 900                         if debugRETZERO {
 901                                 if p.As != obj.ARET {
 902                                         q = newprog()
 903                                         q.Pos = p.Pos
 904                                         q.Link = p.Link
 905                                         p.Link = q
 906                                         p = q
 907                                 }
 908                                 p.As = AADR
 909                                 p.From.Type = obj.TYPE_BRANCH
 910                                 p.From.Offset = 0
 911                                 p.To.Type = obj.TYPE_REG
 912                                 p.To.Reg = REGTMP
 913
 914                         }
 915
 916                         if p.As != obj.ARET {
 917                                 q = newprog()
 918                                 q.Pos = p.Pos
 919                                 q.Link = p.Link
 920                                 p.Link = q
 921                                 p = q
 922                         }
 923
 924                         if retjmp != nil { // retjmp
 925                                 p.As = AB
 926                                 p.To.Type = obj.TYPE_BRANCH
 927                                 p.To.Sym = retjmp
 928                                 p.Spadj = +c.autosize
 929                                 break
 930                         }
 931
 932                         p.As = obj.ARET
 933                         p.To.Type = obj.TYPE_MEM
 934                         p.To.Offset = 0
 935                         p.To.Reg = REGLINK
 936                         p.Spadj = +c.autosize
 937
 938                 case AADD, ASUB:
 939                         if p.To.Type == obj.TYPE_REG && p.To.Reg == REGSP && p.From.Type == obj.TYPE_CONST {
 940                                 if p.As == AADD {
 941                                         p.Spadj = int32(-p.From.Offset)
 942                                 } else {
 943                                         p.Spadj = int32(+p.From.Offset)
 944                                 }
 945                         }
 946
 947                 case obj.AGETCALLERPC:
 948                         if cursym.Leaf() {
 949                                 /* MOVD LR, Rd */
 950                                 p.As = AMOVD
 951                                 p.From.Type = obj.TYPE_REG
 952                                 p.From.Reg = REGLINK
 953                         } else {
 954                                 /* MOVD (RSP), Rd */
 955                                 p.As = AMOVD
 956                                 p.From.Type = obj.TYPE_MEM
 957                                 p.From.Reg = REGSP
 958                         }
 959
 960                 case obj.ADUFFCOPY:
 961                         //  ADR ret_addr, R27
 962                         //  STP (FP, R27), -24(SP)
 963                         //  SUB 24, SP, FP
 964                         //  DUFFCOPY
 965                         // ret_addr:
 966                         //  SUB 8, SP, FP
 967
 968                         q1 := p
 969                         // copy DUFFCOPY from q1 to q4
 970                         q4 := obj.Appendp(p, c.newprog)
 971                         q4.Pos = p.Pos
 972                         q4.As = obj.ADUFFCOPY
 973                         q4.To = p.To
 974
 975                         q1.As = AADR
 976                         q1.From.Type = obj.TYPE_BRANCH
 977                         q1.To.Type = obj.TYPE_REG
 978                         q1.To.Reg = REG_R27
 979
 980                         q2 := obj.Appendp(q1, c.newprog)
 981                         q2.Pos = p.Pos
 982                         q2.As = ASTP
 983                         q2.From.Type = obj.TYPE_REGREG
 984                         q2.From.Reg = REGFP
 985                         q2.From.Offset = int64(REG_R27)
 986                         q2.To.Type = obj.TYPE_MEM
 987                         q2.To.Reg = REGSP
 988                         q2.To.Offset = -24
 989
 990                         // maintain FP for DUFFCOPY
 991                         q3 := obj.Appendp(q2, c.newprog)
 992                         q3.Pos = p.Pos
 993                         q3.As = ASUB
 994                         q3.From.Type = obj.TYPE_CONST
 995                         q3.From.Offset = 24
 996                         q3.Reg = REGSP
 997                         q3.To.Type = obj.TYPE_REG
 998                         q3.To.Reg = REGFP
 999
1000                         q5 := obj.Appendp(q4, c.newprog)
1001                         q5.Pos = p.Pos
1002                         q5.As = ASUB
1003                         q5.From.Type = obj.TYPE_CONST
1004                         q5.From.Offset = 8
1005                         q5.Reg = REGSP
1006                         q5.To.Type = obj.TYPE_REG
1007                         q5.To.Reg = REGFP
1008                         q1.From.SetTarget(q5)
1009                         p = q5
1010
1011                 case obj.ADUFFZERO:
1012                         //  ADR ret_addr, R27
1013                         //  STP (FP, R27), -24(SP)
1014                         //  SUB 24, SP, FP
1015                         //  DUFFZERO
1016                         // ret_addr:
1017                         //  SUB 8, SP, FP
1018
1019                         q1 := p
1020                         // copy DUFFZERO from q1 to q4
1021                         q4 := obj.Appendp(p, c.newprog)
1022                         q4.Pos = p.Pos
1023                         q4.As = obj.ADUFFZERO
1024                         q4.To = p.To
1025
1026                         q1.As = AADR
1027                         q1.From.Type = obj.TYPE_BRANCH
1028                         q1.To.Type = obj.TYPE_REG
1029                         q1.To.Reg = REG_R27
1030
1031                         q2 := obj.Appendp(q1, c.newprog)
1032                         q2.Pos = p.Pos
1033                         q2.As = ASTP
1034                         q2.From.Type = obj.TYPE_REGREG
1035                         q2.From.Reg = REGFP
1036                         q2.From.Offset = int64(REG_R27)
1037                         q2.To.Type = obj.TYPE_MEM
1038                         q2.To.Reg = REGSP
1039                         q2.To.Offset = -24
1040
1041                         // maintain FP for DUFFZERO
1042                         q3 := obj.Appendp(q2, c.newprog)
1043                         q3.Pos = p.Pos
1044                         q3.As = ASUB
1045                         q3.From.Type = obj.TYPE_CONST
1046                         q3.From.Offset = 24
1047                         q3.Reg = REGSP
1048                         q3.To.Type = obj.TYPE_REG
1049                         q3.To.Reg = REGFP
1050
1051                         q5 := obj.Appendp(q4, c.newprog)
1052                         q5.Pos = p.Pos
1053                         q5.As = ASUB
1054                         q5.From.Type = obj.TYPE_CONST
1055                         q5.From.Offset = 8
1056                         q5.Reg = REGSP
1057                         q5.To.Type = obj.TYPE_REG
1058                         q5.To.Reg = REGFP
1059                         q1.From.SetTarget(q5)
1060                         p = q5
1061                 }
1062
1063                 if p.To.Type == obj.TYPE_REG && p.To.Reg == REGSP && p.Spadj == 0 {
1064                         f := c.cursym.Func()
1065                         if f.FuncFlag&objabi.FuncFlag_SPWRITE == 0 {
1066                                 c.cursym.Func().FuncFlag |= objabi.FuncFlag_SPWRITE
1067                                 if ctxt.Debugvlog || !ctxt.IsAsm {
1068                                         ctxt.Logf("auto-SPWRITE: %s %v\n", c.cursym.Name, p)
1069                                         if !ctxt.IsAsm {
1070                                                 ctxt.Diag("invalid auto-SPWRITE in non-assembly")
1071                                                 ctxt.DiagFlush()
1072                                                 log.Fatalf("bad SPWRITE")
1073                                         }
1074                                 }
1075                         }
1076                 }
1077                 if p.From.Type == obj.TYPE_SHIFT && (p.To.Reg == REG_RSP || p.Reg == REG_RSP) {
1078                         offset := p.From.Offset
1079                         op := offset & (3 << 22)
1080                         if op != SHIFT_LL {
1081                                 ctxt.Diag("illegal combination: %v", p)
1082                         }
1083                         r := (offset >> 16) & 31
1084                         shift := (offset >> 10) & 63
1085                         if shift > 4 {
1086                                 // the shift amount is out of range, in order to avoid repeated error
1087                                 // reportings, don't call ctxt.Diag, because asmout case 27 has the
1088                                 // same check.
1089                                 shift = 7
1090                         }
1091                         p.From.Type = obj.TYPE_REG
1092                         p.From.Reg = int16(REG_LSL + r + (shift&7)<<5)
1093                         p.From.Offset = 0
1094                 }
1095         }
1096 }
1097
1098 func nocache(p *obj.Prog) {
1099         p.Optab = 0
1100         p.From.Class = 0
1101         p.To.Class = 0
1102 }
1103
1104 var unaryDst = map[obj.As]bool{
1105         AWORD:  true,
1106         ADWORD: true,
1107         ABL:    true,
1108         AB:     true,
1109         ACLREX: true,
1110 }
1111
1112 var Linkarm64 = obj.LinkArch{
1113         Arch:           sys.ArchARM64,
1114         Init:           buildop,
1115         Preprocess:     preprocess,
1116         Assemble:       span7,
1117         Progedit:       progedit,
1118         UnaryDst:       unaryDst,
1119         DWARFRegisters: ARM64DWARFRegisters,
1120 }