-
Notifications
You must be signed in to change notification settings - Fork 0
/
obj.go
2243 lines (1972 loc) · 65 KB
/
obj.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
// Copyright © 2015 The Go Authors. All rights reserved.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
package riscv
import (
"github.com/bir3/gocompiler/src/cmd/internal/obj"
"github.com/bir3/gocompiler/src/cmd/internal/objabi"
"github.com/bir3/gocompiler/src/cmd/internal/sys"
"fmt"
"log"
)
func buildop(ctxt *obj.Link) {}
func jalToSym(ctxt *obj.Link, p *obj.Prog, lr int16) {
switch p.As {
case obj.ACALL, obj.AJMP, obj.ARET, obj.ADUFFZERO, obj.ADUFFCOPY:
default:
ctxt.Diag("unexpected Prog in jalToSym: %v", p)
return
}
p.As = AJAL
p.Mark |= NEED_CALL_RELOC
p.From.Type = obj.TYPE_REG
p.From.Reg = lr
p.Reg = obj.REG_NONE
}
// progedit is called individually for each *obj.Prog. It normalizes instruction
// formats and eliminates as many pseudo-instructions as possible.
func progedit(ctxt *obj.Link, p *obj.Prog, newprog obj.ProgAlloc) {
// Expand binary instructions to ternary ones.
if p.Reg == obj.REG_NONE {
switch p.As {
case AADDI, ASLTI, ASLTIU, AANDI, AORI, AXORI, ASLLI, ASRLI, ASRAI,
AADDIW, ASLLIW, ASRLIW, ASRAIW, AADDW, ASUBW, ASLLW, ASRLW, ASRAW,
AADD, AAND, AOR, AXOR, ASLL, ASRL, ASUB, ASRA,
AMUL, AMULH, AMULHU, AMULHSU, AMULW, ADIV, ADIVU, ADIVW, ADIVUW,
AREM, AREMU, AREMW, AREMUW:
p.Reg = p.To.Reg
}
}
// Rewrite instructions with constant operands to refer to the immediate
// form of the instruction.
if p.From.Type == obj.TYPE_CONST {
switch p.As {
case AADD:
p.As = AADDI
case ASLT:
p.As = ASLTI
case ASLTU:
p.As = ASLTIU
case AAND:
p.As = AANDI
case AOR:
p.As = AORI
case AXOR:
p.As = AXORI
case ASLL:
p.As = ASLLI
case ASRL:
p.As = ASRLI
case ASRA:
p.As = ASRAI
case AADDW:
p.As = AADDIW
case ASLLW:
p.As = ASLLIW
case ASRLW:
p.As = ASRLIW
case ASRAW:
p.As = ASRAIW
}
}
switch p.As {
case obj.AJMP:
// Turn JMP into JAL ZERO or JALR ZERO.
p.From.Type = obj.TYPE_REG
p.From.Reg = REG_ZERO
switch p.To.Type {
case obj.TYPE_BRANCH:
p.As = AJAL
case obj.TYPE_MEM:
switch p.To.Name {
case obj.NAME_NONE:
p.As = AJALR
case obj.NAME_EXTERN, obj.NAME_STATIC:
// Handled in preprocess.
default:
ctxt.Diag("unsupported name %d for %v", p.To.Name, p)
}
default:
panic(fmt.Sprintf("unhandled type %+v", p.To.Type))
}
case obj.ACALL:
switch p.To.Type {
case obj.TYPE_MEM:
// Handled in preprocess.
case obj.TYPE_REG:
p.As = AJALR
p.From.Type = obj.TYPE_REG
p.From.Reg = REG_LR
default:
ctxt.Diag("unknown destination type %+v in CALL: %v", p.To.Type, p)
}
case obj.AUNDEF:
p.As = AEBREAK
case ASCALL:
// SCALL is the old name for ECALL.
p.As = AECALL
case ASBREAK:
// SBREAK is the old name for EBREAK.
p.As = AEBREAK
case AMOV:
// Put >32-bit constants in memory and load them.
if p.From.Type == obj.TYPE_CONST && p.From.Name == obj.NAME_NONE && p.From.Reg == obj.REG_NONE && int64(int32(p.From.Offset)) != p.From.Offset {
p.From.Type = obj.TYPE_MEM
p.From.Sym = ctxt.Int64Sym(p.From.Offset)
p.From.Name = obj.NAME_EXTERN
p.From.Offset = 0
}
}
}
// addrToReg extracts the register from an Addr, handling special Addr.Names.
func addrToReg(a obj.Addr) int16 {
switch a.Name {
case obj.NAME_PARAM, obj.NAME_AUTO:
return REG_SP
}
return a.Reg
}
// movToLoad converts a MOV mnemonic into the corresponding load instruction.
func movToLoad(mnemonic obj.As) obj.As {
switch mnemonic {
case AMOV:
return ALD
case AMOVB:
return ALB
case AMOVH:
return ALH
case AMOVW:
return ALW
case AMOVBU:
return ALBU
case AMOVHU:
return ALHU
case AMOVWU:
return ALWU
case AMOVF:
return AFLW
case AMOVD:
return AFLD
default:
panic(fmt.Sprintf("%+v is not a MOV", mnemonic))
}
}
// movToStore converts a MOV mnemonic into the corresponding store instruction.
func movToStore(mnemonic obj.As) obj.As {
switch mnemonic {
case AMOV:
return ASD
case AMOVB:
return ASB
case AMOVH:
return ASH
case AMOVW:
return ASW
case AMOVF:
return AFSW
case AMOVD:
return AFSD
default:
panic(fmt.Sprintf("%+v is not a MOV", mnemonic))
}
}
// markRelocs marks an obj.Prog that specifies a MOV pseudo-instruction and
// requires relocation.
func markRelocs(p *obj.Prog) {
switch p.As {
case AMOV, AMOVB, AMOVH, AMOVW, AMOVBU, AMOVHU, AMOVWU, AMOVF, AMOVD:
switch {
case p.From.Type == obj.TYPE_ADDR && p.To.Type == obj.TYPE_REG:
switch p.From.Name {
case obj.NAME_EXTERN, obj.NAME_STATIC:
p.Mark |= NEED_PCREL_ITYPE_RELOC
}
case p.From.Type == obj.TYPE_MEM && p.To.Type == obj.TYPE_REG:
switch p.From.Name {
case obj.NAME_EXTERN, obj.NAME_STATIC:
p.Mark |= NEED_PCREL_ITYPE_RELOC
}
case p.From.Type == obj.TYPE_REG && p.To.Type == obj.TYPE_MEM:
switch p.To.Name {
case obj.NAME_EXTERN, obj.NAME_STATIC:
p.Mark |= NEED_PCREL_STYPE_RELOC
}
}
}
}
// InvertBranch inverts the condition of a conditional branch.
func InvertBranch(as obj.As) obj.As {
switch as {
case ABEQ:
return ABNE
case ABEQZ:
return ABNEZ
case ABGE:
return ABLT
case ABGEU:
return ABLTU
case ABGEZ:
return ABLTZ
case ABGT:
return ABLE
case ABGTU:
return ABLEU
case ABGTZ:
return ABLEZ
case ABLE:
return ABGT
case ABLEU:
return ABGTU
case ABLEZ:
return ABGTZ
case ABLT:
return ABGE
case ABLTU:
return ABGEU
case ABLTZ:
return ABGEZ
case ABNE:
return ABEQ
case ABNEZ:
return ABEQZ
default:
panic("InvertBranch: not a branch")
}
}
// containsCall reports whether the symbol contains a CALL (or equivalent)
// instruction. Must be called after progedit.
func containsCall(sym *obj.LSym) bool {
// CALLs are CALL or JAL(R) with link register LR.
for p := sym.Func().Text; p != nil; p = p.Link {
switch p.As {
case obj.ACALL, obj.ADUFFZERO, obj.ADUFFCOPY:
return true
case AJAL, AJALR:
if p.From.Type == obj.TYPE_REG && p.From.Reg == REG_LR {
return true
}
}
}
return false
}
// setPCs sets the Pc field in all instructions reachable from p.
// It uses pc as the initial value and returns the next available pc.
func setPCs(p *obj.Prog, pc int64) int64 {
for ; p != nil; p = p.Link {
p.Pc = pc
for _, ins := range instructionsForProg(p) {
pc += int64(ins.length())
}
}
return pc
}
// stackOffset updates Addr offsets based on the current stack size.
//
// The stack looks like:
// -------------------
// | |
// | PARAMs |
// | |
// | |
// -------------------
// | Parent RA | SP on function entry
// -------------------
// | |
// | |
// | AUTOs |
// | |
// | |
// -------------------
// | RA | SP during function execution
// -------------------
//
// FixedFrameSize makes other packages aware of the space allocated for RA.
//
// A nicer version of this diagram can be found on slide 21 of the presentation
// attached to https://golang.org/issue/16922#issuecomment-243748180.
func stackOffset(a *obj.Addr, stacksize int64) {
switch a.Name {
case obj.NAME_AUTO:
// Adjust to the top of AUTOs.
a.Offset += stacksize
case obj.NAME_PARAM:
// Adjust to the bottom of PARAMs.
a.Offset += stacksize + 8
}
}
// preprocess generates prologue and epilogue code, computes PC-relative branch
// and jump offsets, and resolves pseudo-registers.
//
// preprocess is called once per linker symbol.
//
// When preprocess finishes, all instructions in the symbol are either
// concrete, real RISC-V instructions or directive pseudo-ops like TEXT,
// PCDATA, and FUNCDATA.
func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
if cursym.Func().Text == nil || cursym.Func().Text.Link == nil {
return
}
// Generate the prologue.
text := cursym.Func().Text
if text.As != obj.ATEXT {
ctxt.Diag("preprocess: found symbol that does not start with TEXT directive")
return
}
stacksize := text.To.Offset
if stacksize == -8 {
// Historical way to mark NOFRAME.
text.From.Sym.Set(obj.AttrNoFrame, true)
stacksize = 0
}
if stacksize < 0 {
ctxt.Diag("negative frame size %d - did you mean NOFRAME?", stacksize)
}
if text.From.Sym.NoFrame() {
if stacksize != 0 {
ctxt.Diag("NOFRAME functions must have a frame size of 0, not %d", stacksize)
}
}
if !containsCall(cursym) {
text.From.Sym.Set(obj.AttrLeaf, true)
if stacksize == 0 {
// A leaf function with no locals has no frame.
text.From.Sym.Set(obj.AttrNoFrame, true)
}
}
// Save LR unless there is no frame.
if !text.From.Sym.NoFrame() {
stacksize += ctxt.Arch.FixedFrameSize
}
cursym.Func().Args = text.To.Val.(int32)
cursym.Func().Locals = int32(stacksize)
prologue := text
if !cursym.Func().Text.From.Sym.NoSplit() {
prologue = stacksplit(ctxt, prologue, cursym, newprog, stacksize) // emit split check
}
if stacksize != 0 {
prologue = ctxt.StartUnsafePoint(prologue, newprog)
// Actually save LR.
prologue = obj.Appendp(prologue, newprog)
prologue.As = AMOV
prologue.From = obj.Addr{Type: obj.TYPE_REG, Reg: REG_LR}
prologue.To = obj.Addr{Type: obj.TYPE_MEM, Reg: REG_SP, Offset: -stacksize}
// Insert stack adjustment.
prologue = obj.Appendp(prologue, newprog)
prologue.As = AADDI
prologue.From = obj.Addr{Type: obj.TYPE_CONST, Offset: -stacksize}
prologue.Reg = REG_SP
prologue.To = obj.Addr{Type: obj.TYPE_REG, Reg: REG_SP}
prologue.Spadj = int32(stacksize)
prologue = ctxt.EndUnsafePoint(prologue, newprog, -1)
// On Linux, in a cgo binary we may get a SIGSETXID signal early on
// before the signal stack is set, as glibc doesn't allow us to block
// SIGSETXID. So a signal may land on the current stack and clobber
// the content below the SP. We store the LR again after the SP is
// decremented.
prologue = obj.Appendp(prologue, newprog)
prologue.As = AMOV
prologue.From = obj.Addr{Type: obj.TYPE_REG, Reg: REG_LR}
prologue.To = obj.Addr{Type: obj.TYPE_MEM, Reg: REG_SP, Offset: 0}
}
if cursym.Func().Text.From.Sym.Wrapper() {
// if(g->panic != nil && g->panic->argp == FP) g->panic->argp = bottom-of-frame
//
// MOV g_panic(g), X5
// BNE X5, ZERO, adjust
// end:
// NOP
// ...rest of function..
// adjust:
// MOV panic_argp(X5), X6
// ADD $(autosize+FIXED_FRAME), SP, X7
// BNE X6, X7, end
// ADD $FIXED_FRAME, SP, X6
// MOV X6, panic_argp(X5)
// JMP end
//
// The NOP is needed to give the jumps somewhere to land.
ldpanic := obj.Appendp(prologue, newprog)
ldpanic.As = AMOV
ldpanic.From = obj.Addr{Type: obj.TYPE_MEM, Reg: REGG, Offset: 4 * int64(ctxt.Arch.PtrSize)} // G.panic
ldpanic.Reg = obj.REG_NONE
ldpanic.To = obj.Addr{Type: obj.TYPE_REG, Reg: REG_X5}
bneadj := obj.Appendp(ldpanic, newprog)
bneadj.As = ABNE
bneadj.From = obj.Addr{Type: obj.TYPE_REG, Reg: REG_X5}
bneadj.Reg = REG_ZERO
bneadj.To.Type = obj.TYPE_BRANCH
endadj := obj.Appendp(bneadj, newprog)
endadj.As = obj.ANOP
last := endadj
for last.Link != nil {
last = last.Link
}
getargp := obj.Appendp(last, newprog)
getargp.As = AMOV
getargp.From = obj.Addr{Type: obj.TYPE_MEM, Reg: REG_X5, Offset: 0} // Panic.argp
getargp.Reg = obj.REG_NONE
getargp.To = obj.Addr{Type: obj.TYPE_REG, Reg: REG_X6}
bneadj.To.SetTarget(getargp)
calcargp := obj.Appendp(getargp, newprog)
calcargp.As = AADDI
calcargp.From = obj.Addr{Type: obj.TYPE_CONST, Offset: stacksize + ctxt.Arch.FixedFrameSize}
calcargp.Reg = REG_SP
calcargp.To = obj.Addr{Type: obj.TYPE_REG, Reg: REG_X7}
testargp := obj.Appendp(calcargp, newprog)
testargp.As = ABNE
testargp.From = obj.Addr{Type: obj.TYPE_REG, Reg: REG_X6}
testargp.Reg = REG_X7
testargp.To.Type = obj.TYPE_BRANCH
testargp.To.SetTarget(endadj)
adjargp := obj.Appendp(testargp, newprog)
adjargp.As = AADDI
adjargp.From = obj.Addr{Type: obj.TYPE_CONST, Offset: int64(ctxt.Arch.PtrSize)}
adjargp.Reg = REG_SP
adjargp.To = obj.Addr{Type: obj.TYPE_REG, Reg: REG_X6}
setargp := obj.Appendp(adjargp, newprog)
setargp.As = AMOV
setargp.From = obj.Addr{Type: obj.TYPE_REG, Reg: REG_X6}
setargp.Reg = obj.REG_NONE
setargp.To = obj.Addr{Type: obj.TYPE_MEM, Reg: REG_X5, Offset: 0} // Panic.argp
godone := obj.Appendp(setargp, newprog)
godone.As = AJAL
godone.From = obj.Addr{Type: obj.TYPE_REG, Reg: REG_ZERO}
godone.To.Type = obj.TYPE_BRANCH
godone.To.SetTarget(endadj)
}
// Update stack-based offsets.
for p := cursym.Func().Text; p != nil; p = p.Link {
stackOffset(&p.From, stacksize)
stackOffset(&p.To, stacksize)
}
// Additional instruction rewriting.
for p := cursym.Func().Text; p != nil; p = p.Link {
switch p.As {
case obj.AGETCALLERPC:
if cursym.Leaf() {
// MOV LR, Rd
p.As = AMOV
p.From.Type = obj.TYPE_REG
p.From.Reg = REG_LR
} else {
// MOV (RSP), Rd
p.As = AMOV
p.From.Type = obj.TYPE_MEM
p.From.Reg = REG_SP
}
case obj.ACALL, obj.ADUFFZERO, obj.ADUFFCOPY:
switch p.To.Type {
case obj.TYPE_MEM:
jalToSym(ctxt, p, REG_LR)
}
case obj.AJMP:
switch p.To.Type {
case obj.TYPE_MEM:
switch p.To.Name {
case obj.NAME_EXTERN, obj.NAME_STATIC:
jalToSym(ctxt, p, REG_ZERO)
}
}
case obj.ARET:
// Replace RET with epilogue.
retJMP := p.To.Sym
if stacksize != 0 {
// Restore LR.
p.As = AMOV
p.From = obj.Addr{Type: obj.TYPE_MEM, Reg: REG_SP, Offset: 0}
p.To = obj.Addr{Type: obj.TYPE_REG, Reg: REG_LR}
p = obj.Appendp(p, newprog)
p.As = AADDI
p.From = obj.Addr{Type: obj.TYPE_CONST, Offset: stacksize}
p.Reg = REG_SP
p.To = obj.Addr{Type: obj.TYPE_REG, Reg: REG_SP}
p.Spadj = int32(-stacksize)
p = obj.Appendp(p, newprog)
}
if retJMP != nil {
p.As = obj.ARET
p.To.Sym = retJMP
jalToSym(ctxt, p, REG_ZERO)
} else {
p.As = AJALR
p.From = obj.Addr{Type: obj.TYPE_REG, Reg: REG_ZERO}
p.Reg = obj.REG_NONE
p.To = obj.Addr{Type: obj.TYPE_REG, Reg: REG_LR}
}
// "Add back" the stack removed in the previous instruction.
//
// This is to avoid confusing pctospadj, which sums
// Spadj from function entry to each PC, and shouldn't
// count adjustments from earlier epilogues, since they
// won't affect later PCs.
p.Spadj = int32(stacksize)
case AADDI:
// Refine Spadjs account for adjustment via ADDI instruction.
if p.To.Type == obj.TYPE_REG && p.To.Reg == REG_SP && p.From.Type == obj.TYPE_CONST {
p.Spadj = int32(-p.From.Offset)
}
}
if p.To.Type == obj.TYPE_REG && p.To.Reg == REGSP && p.Spadj == 0 {
f := cursym.Func()
if f.FuncFlag&objabi.FuncFlag_SPWRITE == 0 {
f.FuncFlag |= objabi.FuncFlag_SPWRITE
if ctxt.Debugvlog || !ctxt.IsAsm {
ctxt.Logf("auto-SPWRITE: %s %v\n", cursym.Name, p)
if !ctxt.IsAsm {
ctxt.Diag("invalid auto-SPWRITE in non-assembly")
ctxt.DiagFlush()
log.Fatalf("bad SPWRITE")
}
}
}
}
}
var callCount int
for p := cursym.Func().Text; p != nil; p = p.Link {
markRelocs(p)
if p.Mark&NEED_CALL_RELOC == NEED_CALL_RELOC {
callCount++
}
}
const callTrampSize = 8 // 2 machine instructions.
maxTrampSize := int64(callCount * callTrampSize)
// Compute instruction addresses. Once we do that, we need to check for
// overextended jumps and branches. Within each iteration, Pc differences
// are always lower bounds (since the program gets monotonically longer,
// a fixed point will be reached). No attempt to handle functions > 2GiB.
for {
big, rescan := false, false
maxPC := setPCs(cursym.Func().Text, 0)
if maxPC+maxTrampSize > (1 << 20) {
big = true
}
for p := cursym.Func().Text; p != nil; p = p.Link {
switch p.As {
case ABEQ, ABEQZ, ABGE, ABGEU, ABGEZ, ABGT, ABGTU, ABGTZ, ABLE, ABLEU, ABLEZ, ABLT, ABLTU, ABLTZ, ABNE, ABNEZ:
if p.To.Type != obj.TYPE_BRANCH {
panic("assemble: instruction with branch-like opcode lacks destination")
}
offset := p.To.Target().Pc - p.Pc
if offset < -4096 || 4096 <= offset {
// Branch is long. Replace it with a jump.
jmp := obj.Appendp(p, newprog)
jmp.As = AJAL
jmp.From = obj.Addr{Type: obj.TYPE_REG, Reg: REG_ZERO}
jmp.To = obj.Addr{Type: obj.TYPE_BRANCH}
jmp.To.SetTarget(p.To.Target())
p.As = InvertBranch(p.As)
p.To.SetTarget(jmp.Link)
// We may have made previous branches too long,
// so recheck them.
rescan = true
}
case AJAL:
// Linker will handle the intersymbol case and trampolines.
if p.To.Target() == nil {
if !big {
break
}
// This function is going to be too large for JALs
// to reach trampolines. Replace with AUIPC+JALR.
jmp := obj.Appendp(p, newprog)
jmp.As = AJALR
jmp.From = p.From
jmp.To = obj.Addr{Type: obj.TYPE_REG, Reg: REG_TMP}
p.As = AAUIPC
p.Mark = (p.Mark &^ NEED_CALL_RELOC) | NEED_PCREL_ITYPE_RELOC
p.SetFrom3(obj.Addr{Type: obj.TYPE_CONST, Offset: p.To.Offset, Sym: p.To.Sym})
p.From = obj.Addr{Type: obj.TYPE_CONST, Offset: 0}
p.Reg = obj.REG_NONE
p.To = obj.Addr{Type: obj.TYPE_REG, Reg: REG_TMP}
rescan = true
break
}
offset := p.To.Target().Pc - p.Pc
if offset < -(1<<20) || (1<<20) <= offset {
// Replace with 2-instruction sequence. This assumes
// that TMP is not live across J instructions, since
// it is reserved by SSA.
jmp := obj.Appendp(p, newprog)
jmp.As = AJALR
jmp.From = p.From
jmp.To = obj.Addr{Type: obj.TYPE_REG, Reg: REG_TMP}
// p.From is not generally valid, however will be
// fixed up in the next loop.
p.As = AAUIPC
p.From = obj.Addr{Type: obj.TYPE_BRANCH, Sym: p.From.Sym}
p.From.SetTarget(p.To.Target())
p.Reg = obj.REG_NONE
p.To = obj.Addr{Type: obj.TYPE_REG, Reg: REG_TMP}
rescan = true
}
}
}
if !rescan {
break
}
}
// Now that there are no long branches, resolve branch and jump targets.
// At this point, instruction rewriting which changes the number of
// instructions will break everything--don't do it!
for p := cursym.Func().Text; p != nil; p = p.Link {
switch p.As {
case ABEQ, ABEQZ, ABGE, ABGEU, ABGEZ, ABGT, ABGTU, ABGTZ, ABLE, ABLEU, ABLEZ, ABLT, ABLTU, ABLTZ, ABNE, ABNEZ:
switch p.To.Type {
case obj.TYPE_BRANCH:
p.To.Type, p.To.Offset = obj.TYPE_CONST, p.To.Target().Pc-p.Pc
case obj.TYPE_MEM:
panic("unhandled type")
}
case AJAL:
// Linker will handle the intersymbol case and trampolines.
if p.To.Target() != nil {
p.To.Type, p.To.Offset = obj.TYPE_CONST, p.To.Target().Pc-p.Pc
}
case AAUIPC:
if p.From.Type == obj.TYPE_BRANCH {
low, high, err := Split32BitImmediate(p.From.Target().Pc - p.Pc)
if err != nil {
ctxt.Diag("%v: jump displacement %d too large", p, p.To.Target().Pc-p.Pc)
}
p.From = obj.Addr{Type: obj.TYPE_CONST, Offset: high, Sym: cursym}
p.Link.From.Offset = low
}
}
}
// Validate all instructions - this provides nice error messages.
for p := cursym.Func().Text; p != nil; p = p.Link {
for _, ins := range instructionsForProg(p) {
ins.validate(ctxt)
}
}
}
func stacksplit(ctxt *obj.Link, p *obj.Prog, cursym *obj.LSym, newprog obj.ProgAlloc, framesize int64) *obj.Prog {
// Leaf function with no frame is effectively NOSPLIT.
if framesize == 0 {
return p
}
if ctxt.Flag_maymorestack != "" {
// Save LR and REGCTXT
const frameSize = 16
p = ctxt.StartUnsafePoint(p, newprog)
// Spill Arguments. This has to happen before we open
// any more frame space.
p = cursym.Func().SpillRegisterArgs(p, newprog)
// MOV LR, -16(SP)
p = obj.Appendp(p, newprog)
p.As = AMOV
p.From = obj.Addr{Type: obj.TYPE_REG, Reg: REG_LR}
p.To = obj.Addr{Type: obj.TYPE_MEM, Reg: REG_SP, Offset: -frameSize}
// ADDI $-16, SP
p = obj.Appendp(p, newprog)
p.As = AADDI
p.From = obj.Addr{Type: obj.TYPE_CONST, Offset: -frameSize}
p.Reg = REG_SP
p.To = obj.Addr{Type: obj.TYPE_REG, Reg: REG_SP}
p.Spadj = frameSize
// MOV REGCTXT, 8(SP)
p = obj.Appendp(p, newprog)
p.As = AMOV
p.From = obj.Addr{Type: obj.TYPE_REG, Reg: REG_CTXT}
p.To = obj.Addr{Type: obj.TYPE_MEM, Reg: REG_SP, Offset: 8}
// CALL maymorestack
p = obj.Appendp(p, newprog)
p.As = obj.ACALL
p.To.Type = obj.TYPE_BRANCH
// See ../x86/obj6.go
p.To.Sym = ctxt.LookupABI(ctxt.Flag_maymorestack, cursym.ABI())
jalToSym(ctxt, p, REG_X5)
// Restore LR and REGCTXT
// MOV 8(SP), REGCTXT
p = obj.Appendp(p, newprog)
p.As = AMOV
p.From = obj.Addr{Type: obj.TYPE_MEM, Reg: REG_SP, Offset: 8}
p.To = obj.Addr{Type: obj.TYPE_REG, Reg: REG_CTXT}
// MOV (SP), LR
p = obj.Appendp(p, newprog)
p.As = AMOV
p.From = obj.Addr{Type: obj.TYPE_MEM, Reg: REG_SP, Offset: 0}
p.To = obj.Addr{Type: obj.TYPE_REG, Reg: REG_LR}
// ADDI $16, SP
p = obj.Appendp(p, newprog)
p.As = AADDI
p.From = obj.Addr{Type: obj.TYPE_CONST, Offset: frameSize}
p.Reg = REG_SP
p.To = obj.Addr{Type: obj.TYPE_REG, Reg: REG_SP}
p.Spadj = -frameSize
// Unspill arguments
p = cursym.Func().UnspillRegisterArgs(p, newprog)
p = ctxt.EndUnsafePoint(p, newprog, -1)
}
// Jump back to here after morestack returns.
startPred := p
// MOV g_stackguard(g), X6
p = obj.Appendp(p, newprog)
p.As = AMOV
p.From.Type = obj.TYPE_MEM
p.From.Reg = REGG
p.From.Offset = 2 * int64(ctxt.Arch.PtrSize) // G.stackguard0
if cursym.CFunc() {
p.From.Offset = 3 * int64(ctxt.Arch.PtrSize) // G.stackguard1
}
p.To.Type = obj.TYPE_REG
p.To.Reg = REG_X6
// Mark the stack bound check and morestack call async nonpreemptible.
// If we get preempted here, when resumed the preemption request is
// cleared, but we'll still call morestack, which will double the stack
// unnecessarily. See issue #35470.
p = ctxt.StartUnsafePoint(p, newprog)
var to_done, to_more *obj.Prog
if framesize <= objabi.StackSmall {
// small stack
// // if SP > stackguard { goto done }
// BLTU stackguard, SP, done
p = obj.Appendp(p, newprog)
p.As = ABLTU
p.From.Type = obj.TYPE_REG
p.From.Reg = REG_X6
p.Reg = REG_SP
p.To.Type = obj.TYPE_BRANCH
to_done = p
} else {
// large stack: SP-framesize < stackguard-StackSmall
offset := int64(framesize) - objabi.StackSmall
if framesize > objabi.StackBig {
// Such a large stack we need to protect against underflow.
// The runtime guarantees SP > objabi.StackBig, but
// framesize is large enough that SP-framesize may
// underflow, causing a direct comparison with the
// stack guard to incorrectly succeed. We explicitly
// guard against underflow.
//
// MOV $(framesize-StackSmall), X7
// BLTU SP, X7, label-of-call-to-morestack
p = obj.Appendp(p, newprog)
p.As = AMOV
p.From.Type = obj.TYPE_CONST
p.From.Offset = offset
p.To.Type = obj.TYPE_REG
p.To.Reg = REG_X7
p = obj.Appendp(p, newprog)
p.As = ABLTU
p.From.Type = obj.TYPE_REG
p.From.Reg = REG_SP
p.Reg = REG_X7
p.To.Type = obj.TYPE_BRANCH
to_more = p
}
// Check against the stack guard. We've ensured this won't underflow.
// ADD $-(framesize-StackSmall), SP, X7
// // if X7 > stackguard { goto done }
// BLTU stackguard, X7, done
p = obj.Appendp(p, newprog)
p.As = AADDI
p.From.Type = obj.TYPE_CONST
p.From.Offset = -offset
p.Reg = REG_SP
p.To.Type = obj.TYPE_REG
p.To.Reg = REG_X7
p = obj.Appendp(p, newprog)
p.As = ABLTU
p.From.Type = obj.TYPE_REG
p.From.Reg = REG_X6
p.Reg = REG_X7
p.To.Type = obj.TYPE_BRANCH
to_done = p
}
// Spill the register args that could be clobbered by the
// morestack code
p = ctxt.EmitEntryStackMap(cursym, p, newprog)
p = cursym.Func().SpillRegisterArgs(p, newprog)
// CALL runtime.morestack(SB)
p = obj.Appendp(p, newprog)
p.As = obj.ACALL
p.To.Type = obj.TYPE_BRANCH
if cursym.CFunc() {
p.To.Sym = ctxt.Lookup("runtime.morestackc")
} else if !cursym.Func().Text.From.Sym.NeedCtxt() {
p.To.Sym = ctxt.Lookup("runtime.morestack_noctxt")
} else {
p.To.Sym = ctxt.Lookup("runtime.morestack")
}
if to_more != nil {
to_more.To.SetTarget(p)
}
jalToSym(ctxt, p, REG_X5)
p = cursym.Func().UnspillRegisterArgs(p, newprog)
p = ctxt.EndUnsafePoint(p, newprog, -1)
// JMP start
p = obj.Appendp(p, newprog)
p.As = AJAL
p.To = obj.Addr{Type: obj.TYPE_BRANCH}
p.From = obj.Addr{Type: obj.TYPE_REG, Reg: REG_ZERO}
p.To.SetTarget(startPred.Link)
// placeholder for to_done's jump target
p = obj.Appendp(p, newprog)
p.As = obj.ANOP // zero-width place holder
to_done.To.SetTarget(p)
return p
}
// signExtend sign extends val starting at bit bit.
func signExtend(val int64, bit uint) int64 {
return val << (64 - bit) >> (64 - bit)
}
// Split32BitImmediate splits a signed 32-bit immediate into a signed 20-bit
// upper immediate and a signed 12-bit lower immediate to be added to the upper
// result. For example, high may be used in LUI and low in a following ADDI to
// generate a full 32-bit constant.
func Split32BitImmediate(imm int64) (low, high int64, err error) {
if !immIFits(imm, 32) {
return 0, 0, fmt.Errorf("immediate does not fit in 32 bits: %d", imm)
}
// Nothing special needs to be done if the immediate fits in 12 bits.
if immIFits(imm, 12) {
return imm, 0, nil
}
high = imm >> 12
// The bottom 12 bits will be treated as signed.
//
// If that will result in a negative 12 bit number, add 1 to
// our upper bits to adjust for the borrow.
//
// It is not possible for this increment to overflow. To
// overflow, the 20 top bits would be 1, and the sign bit for
// the low 12 bits would be set, in which case the entire 32
// bit pattern fits in a 12 bit signed value.
if imm&(1<<11) != 0 {
high++
}
low = signExtend(imm, 12)
high = signExtend(high, 20)
return low, high, nil
}
func regVal(r, min, max uint32) uint32 {
if r < min || r > max {
panic(fmt.Sprintf("register out of range, want %d < %d < %d", min, r, max))
}
return r - min
}
// regI returns an integer register.
func regI(r uint32) uint32 {
return regVal(r, REG_X0, REG_X31)
}
// regF returns a float register.
func regF(r uint32) uint32 {
return regVal(r, REG_F0, REG_F31)
}
// regAddr extracts a register from an Addr.
func regAddr(a obj.Addr, min, max uint32) uint32 {
if a.Type != obj.TYPE_REG {
panic(fmt.Sprintf("ill typed: %+v", a))
}
return regVal(uint32(a.Reg), min, max)
}
// regIAddr extracts the integer register from an Addr.
func regIAddr(a obj.Addr) uint32 {
return regAddr(a, REG_X0, REG_X31)
}
// regFAddr extracts the float register from an Addr.
func regFAddr(a obj.Addr) uint32 {
return regAddr(a, REG_F0, REG_F31)
}