Repository navigation
Expand file tree
/
Copy pathfunc.go
More file actions
1090 lines (983 loc) · 28.5 KB
/
Copy pathfunc.go
File metadata and controls
1090 lines (983 loc) · 28.5 KB
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 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package ir
// This file implements the Function and BasicBlock types.
import (
"bytes"
"fmt"
"go/ast"
"go/format"
"go/token"
"go/types"
"io"
"os"
"sort"
"strings"
"honnef.co/go/tools/go/types/typeutil"
)
// addEdge adds a control-flow graph edge from from to to.
func addEdge(from, to *BasicBlock) {
from.Succs = append(from.Succs, to)
to.Preds = append(to.Preds, from)
}
// Control returns the last instruction in the block.
func (b *BasicBlock) Control() Instruction {
if len(b.Instrs) == 0 {
return nil
}
return b.Instrs[len(b.Instrs)-1]
}
// SigmaFor returns the sigma node for v coming from pred.
func (b *BasicBlock) SigmaFor(v Value, pred *BasicBlock) *Sigma {
for _, instr := range b.Instrs {
sigma, ok := instr.(*Sigma)
if !ok {
// no more sigmas
return nil
}
if sigma.From == pred && sigma.X == v {
return sigma
}
}
return nil
}
// Parent returns the function that contains block b.
func (b *BasicBlock) Parent() *Function { return b.parent }
// String returns a human-readable label of this block.
// It is not guaranteed unique within the function.
func (b *BasicBlock) String() string {
return fmt.Sprintf("%d", b.Index)
}
// emit appends an instruction to the current basic block.
// If the instruction defines a Value, it is returned.
func (b *BasicBlock) emit(i Instruction, source ast.Node) Value {
i.setSource(source)
i.setBlock(b)
b.Instrs = append(b.Instrs, i)
v, _ := i.(Value)
return v
}
// predIndex returns the i such that b.Preds[i] == c or panics if
// there is none.
func (b *BasicBlock) predIndex(c *BasicBlock) int {
for i, pred := range b.Preds {
if pred == c {
return i
}
}
panic(fmt.Sprintf("no edge %s -> %s", c, b))
}
// succIndex returns the i such that b.Succs[i] == c or -1 if there is none.
func (b *BasicBlock) succIndex(c *BasicBlock) int {
for i, succ := range b.Succs {
if succ == c {
return i
}
}
return -1
}
// hasPhi returns true if b.Instrs contains φ-nodes.
func (b *BasicBlock) hasPhi() bool {
_, ok := b.Instrs[0].(*Phi)
return ok
}
func (b *BasicBlock) Phis() []Instruction {
return b.phis()
}
// phis returns the prefix of b.Instrs containing all the block's φ-nodes.
func (b *BasicBlock) phis() []Instruction {
for i, instr := range b.Instrs {
if _, ok := instr.(*Phi); !ok {
return b.Instrs[:i]
}
}
return nil // unreachable in well-formed blocks
}
// replacePred replaces all occurrences of p in b's predecessor list with q.
// Ordinarily there should be at most one.
func (b *BasicBlock) replacePred(p, q *BasicBlock) {
for i, pred
10BC8
:= range b.Preds {
if pred == p {
b.Preds[i] = q
}
}
}
// replaceSucc replaces all occurrences of p in b's successor list with q.
// Ordinarily there should be at most one.
func (b *BasicBlock) replaceSucc(p, q *BasicBlock) {
for i, succ := range b.Succs {
if succ == p {
b.Succs[i] = q
}
}
}
// removePred removes all occurrences of p in b's
// predecessor list and φ-nodes.
// Ordinarily there should be at most one.
func (b *BasicBlock) removePred(p *BasicBlock) {
phis := b.phis()
// We must preserve edge order for φ-nodes.
j := 0
for i, pred := range b.Preds {
if pred != p {
b.Preds[j] = b.Preds[i]
// Strike out φ-edge too.
for _, instr := range phis {
phi := instr.(*Phi)
phi.Edges[j] = phi.Edges[i]
}
j++
}
}
// Nil out b.Preds[j:] and φ-edges[j:] to aid GC.
for i := j; i < len(b.Preds); i++ {
b.Preds[i] = nil
for _, instr := range phis {
instr.(*Phi).Edges[i] = nil
}
}
b.Preds = b.Preds[:j]
for _, instr := range phis {
phi := instr.(*Phi)
phi.Edges = phi.Edges[:j]
}
}
// Destinations associated with unlabelled for/switch/select stmts.
// We push/pop one of these as we enter/leave each construct and for
// each BranchStmt we scan for the innermost target of the right type.
type targets struct {
tail *targets // rest of stack
_break *BasicBlock
_continue *BasicBlock
_fallthrough *BasicBlock
}
// Destinations associated with a labelled block.
// We populate these as labels are encountered in forward gotos or
// labelled statements.
// Forward gotos are resolved once it is known which statement they
// are associated with inside the Function.
type lblock struct {
label *types.Label // Label targeted by the blocks.
resolved bool // _goto block encountered (back jump or resolved fwd jump)
_goto *BasicBlock
_break *BasicBlock
_continue *BasicBlock
}
// label returns the symbol denoted by a label identifier.
//
// label should be a non-blank identifier (label.Name != "_").
func (f *Function) label(label *ast.Ident) *types.Label {
return f.Pkg.objectOf(label).(*types.Label)
}
// lblockOf returns the branch target associated with the
// specified label, creating it if needed.
func (f *Function) lblockOf(label *types.Label) *lblock {
lb := f.lblocks[label]
if lb == nil {
lb = &lblock{
label: label,
_goto: f.newBasicBlock(label.Name()),
}
if f.lblocks == nil {
f.lblocks = make(map[*types.Label]*lblock)
}
f.lblocks[label] = lb
}
return lb
}
// labelledBlock searches f for the block of the specified label.
//
// If f is a yield function, it additionally searches ancestor Functions
// corresponding to enclosing range-over-func statements within the
// same source function, so the returned block may belong to a different Function.
func labelledBlock(f *Function, label *types.Label, tok token.Token) *BasicBlock {
if lb := f.lblocks[label]; lb != nil {
var block *BasicBlock
switch tok {
case token.BREAK:
block = lb._break
case token.CONTINUE:
block = lb._continue
case token.GOTO:
block = lb._goto
}
if block != nil {
return block
}
}
// Search ancestors if this is a yield function.
if f.jump != nil {
return labelledBlock(f.parent, label, tok)
}
return nil
}
// targetedBlock looks for the nearest block in f.targets
// (and f's ancestors) that matches tok's type, and returns
// the block and function it was found in.
func targetedBlock(f *Function, tok token.Token) *BasicBlock {
if f == nil {
return nil
}
for t := f.targets; t != nil; t = t.tail {
var block *BasicBlock
switch tok {
case token.BREAK:
block = t._break
case token.CONTINUE:
block = t._continue
case token.FALLTHROUGH:
block = t._fallthrough
}
if block != nil {
return block
}
}
// Search f's ancestors (in case f is a yield function).
return targetedBlock(f.parent, tok)
}
// addResultVar adds a result for a variable v to f.results and v to f.returnVars.
func (f *Function) addResultVar(v *types.Var, source ast.Node) {
name := v.Name()
if name == "" {
name = fmt.Sprintf("res.%d", len(f.results))
}
result := emitLocalVar(f, v, source)
result.comment = name
f.results = append(f.results, result)
f.returnVars = append(f.returnVars, v)
}
func (f *Function) addParamVar(v *types.Var, source ast.Node) *Parameter {
name := v.Name()
if name == "" {
name = fmt.Sprintf("arg%d", len(f.Params))
}
var b *BasicBlock
if len(f.Blocks) > 0 {
b = f.Blocks[0]
}
param := &Parameter{name: name}
param.setBlock(b)
param.setType(v.Type())
param.setSource(source)
param.object = v
f.Params = append(f.Params, param)
if b != nil {
f.Blocks[0].Instrs = append(f.Blocks[0].Instrs, param)
}
return param
}
// addSpilledParam declares a parameter that is pre-spilled to the
// stack; the function body will load/store the spilled location.
// Subsequent lifting will eliminate spills where possible.
func (f *Function) addSpilledParam(obj *types.Var, source ast.Node) {
param := f.addParamVar(obj, source)
spill := emitLocalVar(f, obj, source)
emitStore(f, spill, param, source)
// f.emit(&Store{Addr: spill, Val: param})
}
// startBody initializes the function prior to generating IR code for its body.
// Precondition: f.Type() already set.
func (f *Function) startBody() {
entry := f.newBasicBlock("entry")
f.currentBlock = entry
f.vars = make(map[*types.Var]Value) // needed for some synthetics, e.g. init
}
func (f *Function) blockset(i int) *BlockSet {
bs := &f.blocksets[i]
if len(bs.values) != len(f.Blocks) {
if cap(bs.values) >= len(f.Blocks) {
bs.values = bs.values[:len(f.Blocks)]
bs.Clear()
} else {
bs.values = make([]bool, len(f.Blocks))
}
} else {
bs.Clear()
}
return bs
}
func (f *Function) exitBlock() {
old := f.currentBlock
f.Exit = f.newBasicBlock("exit")
f.currentBlock = f.Exit
results := make([]Value, len(f.results))
// Run function calls deferred in this
// function when explicitly returning from it.
f.emit(new(RunDefers), nil)
for i, r := range f.results {
results[i] = emitLoad(f, r, nil)
}
f.emit(&Return{Results: results}, nil)
f.currentBlock = old
}
// createSyntacticParams populates f.Params and generates code (spills
// and named result locals) for all the parameters declared in the
// syntax. In addition it populates the f.objects mapping.
//
// Preconditions:
// f.startBody() was called.
// Postcondition:
// len(f.Params) == len(f.Signature.Params) + (f.Signature.Recv() ? 1 : 0)
func (f *Function) createSyntacticParams(recv *ast.FieldList, functype *ast.FuncType) {
// Receiver (at most one inner iteration).
if recv != nil {
for _, field := range recv.List {
for _, n := range field.Names {
f.addSpilledParam(identVar(f, n), n)
}
// Anonymous receiver? No need to spill.
if field.Names == nil {
f.addParamVar(f.Signature.Recv(), field)
}
}
}
// Parameters.
if functype.Params != nil {
n := len(f.Params) // 1 if has recv, 0 otherwise
for _, field := range functype.Params.List {
for _, n := range field.Names {
f.addSpilledParam(identVar(f, n), n)
}
// Anonymous parameter? No need to spill.
if field.Names == nil {
f.addParamVar(f.Signature.Params().At(len(f.Params)-n), field)
}
}
}
// Results.
if functype.Results != nil {
for _, field := range functype.Results.List {
// Implicit "var" decl of locals for named results.
for _, n := range field.Names {
v := identVar(f, n)
f.addResultVar(v, n)
}
// Implicit "var" decl of local for an unnamed result.
if field.Names == nil {
v := f.Signature.Results().At(len(f.results))
f.addResultVar(v, field.Type)
}
}
}
}
// createDeferStack initializes fn.deferstack to a local variable
// initialized to a ssa:deferstack() call.
func (fn *Function) createDeferStack() {
// Each syntactic function makes a call to ssa:deferstack,
// which is spilled to a local. Unused ones are later removed.
fn.deferstack = newVar("defer$stack", tDeferStack)
call := &Call{Call: CallCommon{Value: vDeferStack}}
call.setType(tDeferStack)
deferstack := fn.emit(call, nil)
spill := emitLocalVar(fn, fn.deferstack, nil)
emitStore(fn, spill, deferstack, nil)
}
func numberNodes(f *Function) {
var base ID
for _, b := range f.Blocks {
for _, instr := range b.Instrs {
if instr == nil {
continue
}
base++
instr.setID(base)
}
}
}
func updateOperandsReferrers(instr Instruction, ops []*Value) {
for _, op := range ops {
if r := *op; r != nil {
if refs := (*op).Referrers(); refs != nil {
if len(*refs) == 0 {
// per median, each value has two referrers, so we can avoid one call into growslice
//
// Note: we experimented with allocating
// sequential scratch space, but we
// couldn't find a value that gave better
// performance than making many individual
// allocations
*refs = make([]Instruction, 1, 2)
(*refs)[0] = instr
} else {
*refs = append(*refs, instr)
}
}
}
}
}
// buildReferrers populates the def/use information in all non-nil
// Value.Referrers slice.
// Precondition: all such slices are initially empty.
func buildReferrers(f *Function) {
var rands []*Value
for _, b := range f.Blocks {
for _, instr := range b.Instrs {
rands = instr.Operands(rands[:0]) // recycle storage
updateOperandsReferrers(instr, rands)
}
}
for _, c := range f.consts {
rands = c.c.Operands(rands[:0])
updateOperandsReferrers(c.c, rands)
}
}
func (f *Function) emitConsts() {
defer func() {
f.consts = nil
f.aggregateConsts = typeutil.Map[[]*AggregateConst]{}
}()
if len(f.Blocks) == 0 {
return
}
// TODO(dh): our deduplication only works on booleans and
// integers. other constants are represented as pointers to
// things.
head := make([]constValue, 0, len(f.consts))
for _, c := range f.consts {
if len(*c.c.Referrers()) == 0 {
// TODO(dh): killing a const may make other consts dead, too
killInstruction(c.c)
} else {
head = append(head, c)
}
}
sort.Slice(head, func(i, j int) bool {
return head[i].idx < head[j].idx
})
entry := f.Blocks[0]
instrs := make([]Instruction, 0, len(entry.Instrs)+len(head))
for _, c := range head {
instrs = append(instrs, c.c)
}
f.aggregateConsts.Iterate(func(key types.Type, value []*AggregateConst) {
for _, c := range value {
instrs = append(instrs, c)
}
})
instrs = append(instrs, entry.Instrs...)
entry.Instrs = instrs
}
// buildFakeExits ensures that every block in the function is
// reachable in reverse from the Exit block. This is required to build
// a full post-dominator tree, and to ensure the exit block's
// inclusion in the dominator tree.
func buildFakeExits(fn *Function) {
// Find back-edges via forward DFS
fn.fakeExits = BlockSet{values: make([]bool, len(fn.Blocks))}
seen := fn.blockset(0)
backEdges := fn.blockset(1)
var dfs func(b *BasicBlock)
dfs = func(b *BasicBlock) {
if !seen.Add(b) {
backEdges.Add(b)
return
}
for _, pred := range b.Succs {
dfs(pred)
}
}
dfs(fn.Blocks[0])
buildLoop:
for {
seen := fn.blockset(2)
var dfs func(b *BasicBlock)
dfs = func(b *BasicBlock) {
if !seen.Add(b) {
return
}
for _, pred := range b.Preds {
dfs(pred)
}
if b == fn.Exit {
for _, b := range fn.Blocks {
if fn.fakeExits.Has(b) {
dfs(b)
}
}
}
}
dfs(fn.Exit)
for _, b := range fn.Blocks {
if !seen.Has(b) && backEdges.Has(b) {
// Block b is not reachable from the exit block. Add a
// fake jump from b to exit, then try again. Note that we
// only add one fake edge at a time, as it may make
// multiple blocks reachable.
//
// We only consider those blocks that have back edges.
// Any unreachable block that doesn't have a back edge
// must flow into a loop, which by definition has a
// back edge. Thus, by looking for loops, we should
// need fewer fake edges overall.
fn.fakeExits.Add(b)
continue buildLoop
}
}
break
}
}
// finishBody() finalizes the function after IR code generation of its body.
func (f *Function) finishBody() {
f.currentBlock = nil
f.lblocks = nil
// Remove from f.Locals any Allocs that escape to the heap.
j := 0
for _, l := range f.Locals {
if !l.Heap {
f.Locals[j] = l
j++
}
}
// Nil out f.Locals[j:] to aid GC.
for i := j; i < len(f.Locals); i++ {
f.Locals[i] = nil
}
f.Locals = f.Locals[:j]
optimizeBlocks(f)
buildFakeExits(f)
buildReferrers(f)
buildDomTree(f)
buildPostDomTree(f)
if f.Prog.mode&NaiveForm == 0 {
for lift(f) {
}
if doSimplifyConstantCompositeValues {
for simplifyConstantCompositeValues(f) {
}
}
}
// emit constants after lifting, because lifting may produce new constants, but before other variable splitting,
// because it expects constants to have been deduplicated.
f.emitConsts()
if f.Prog.mode&SplitAfterNewInformation != 0 {
splitOnNewInformation(f.Blocks[0], &StackMap{})
}
// clear remaining builder state
f.results = nil // (used by lifting)
f.deferstack = nil // (used by lifting)
f.vars = nil // (used by lifting)
f.goversion = ""
numberNodes(f)
defer f.wr.Close()
f.wr.WriteFunc("start", "start", f)
if f.Prog.mode&PrintFunctions != 0 {
printMu.Lock()
f.WriteTo(os.Stdout)
printMu.Unlock()
}
if f.Prog.mode&SanityCheckFunctions != 0 {
mustSanityCheck(f, nil)
}
}
func isUselessPhi(phi *Phi) (Value, bool) {
var v0 Value
for _, e := range phi.Edges {
if e == phi {
continue
}
if v0 == nil {
v0 = e
}
if v0 != e {
if v0, ok := v0.(*Const); ok {
if e, ok := e.(*Const); ok {
if v0.typ == e.typ && v0.Value == e.Value {
continue
}
}
}
return nil, false
}
}
return v0, true
}
func (f *Function) RemoveNilBlocks() {
f.removeNilBlocks()
}
// removeNilBlocks eliminates nils from f.Blocks and updates each
// BasicBlock.Index. Use this after any pass that may delete blocks.
func (f *Function) removeNilBlocks() {
j := 0
for _, b := range f.Blocks {
if b != nil {
b.Index = j
f.Blocks[j] = b
j++
}
}
// Nil out f.Blocks[j:] to aid GC.
for i := j; i < len(f.Blocks); i++ {
f.Blocks[i] = nil
}
f.Blocks = f.Blocks[:j]
}
// SetDebugMode sets the debug mode for package pkg. If true, all its
// functions will include full debug info. This greatly increases the
// size of the instruction stream, and causes Functions to depend upon
// the ASTs, potentially keeping them live in memory for longer.
func (pkg *Package) SetDebugMode(debug bool) {
// TODO(adonovan): do we want ast.File granularity?
pkg.debug = debug
}
// debugInfo reports whether debug info is wanted for this function.
func (f *Function) debugInfo() bool {
return f.Pkg != nil && f.Pkg.debug
}
// lookup returns the address of the named variable identified by obj
// that is local to function f or one of its enclosing functions.
// If escaping, the reference comes from a potentially escaping pointer
// expression and the referent must be heap-allocated.
// We assume the referent is a *Alloc or *Phi.
// (The only Phis at this stage are those created directly by go1.22 "for" loops.)
func (f *Function) lookup(obj *types.Var, escaping bool) Value {
if v, ok := f.vars[obj]; ok {
if escaping {
switch v := v.(type) {
case *Alloc:
v.Heap = true
case *Phi:
for _, edge := range v.Edges {
if alloc, ok := edge.(*Alloc); ok {
alloc.Heap = true
}
}
}
}
return v // function-local var (address)
}
// Definition must be in an enclosing function;
// plumb it through intervening closures.
if f.parent == nil {
panic("no ir.Value for " + obj.String())
}
outer := f.parent.lookup(obj, true) // escaping
v := &FreeVar{
name: obj.Name(),
typ: outer.Type(),
outer: outer,
parent: f,
}
f.vars[obj] = v
f.FreeVars = append(f.FreeVars, v)
return v
}
// emit emits the specified instruction to function f.
func (f *Function) emit(instr Instruction, source ast.Node) Value {
return f.currentBlock.emit(instr, source)
}
// RelString returns the full name of this function, qualified by
// package name, receiver type, etc.
//
// The specific formatting rules are not guaranteed and may change.
//
// Examples:
//
// "math.IsNaN" // a package-level function
// "(*bytes.Buffer).Bytes" // a declared method or a wrapper
// "(*bytes.Buffer).Bytes$thunk" // thunk (func wrapping method; receiver is param 0)
// "(*bytes.Buffer).Bytes$bound" // bound (func wrapping method; receiver supplied by closure)
// "main.main$1" // an anonymous function in main
// "main.init#1" // a declared init function
// "main.init" // the synthesized package initializer
//
// When these functions are referred to from within the same package
// (i.e. from == f.Pkg.Object), they are rendered without the package path.
// For example: "IsNaN", "(*Buffer).Bytes", etc.
//
// All non-synthetic functions have distinct package-qualified names.
// (But two methods may have the same name "(T).f" if one is a synthetic
// wrapper promoting a non-exported method "f" from another package; in
// that case, the strings are equal but the identifiers "f" are distinct.)
func (f *Function) RelString(from *types.Package) string {
// Anonymous?
if f.parent != nil {
// An anonymous function's Name() looks like "parentName$1",
// but its String() should include the type/package/etc.
parent := f.parent.RelString(from)
for i, anon := range f.parent.AnonFuncs {
if anon == f {
return fmt.Sprintf("%s$%d", parent, 1+i)
}
}
return f.name // should never happen
}
// Method (declared or wrapper)?
if recv := f.Signature.Recv(); recv != nil {
return f.relMethod(from, recv.Type())
}
// Thunk?
if f.method != nil {
return f.relMethod(from, f.method.Recv())
}
// Bound?
if len(f.FreeVars) == 1 && strings.HasSuffix(f.name, "$bound") {
return f.relMethod(from, f.FreeVars[0].Type())
}
// Package-level function?
// Prefix with package name for cross-package references only.
if p := f.pkg(); p != nil && p != from {
return fmt.Sprintf("%s.%s", p.Path(), f.name)
}
// Unknown.
return f.name
}
func (f *Function) relMethod(from *types.Package, recv types.Type) string {
return fmt.Sprintf("(%s).%s", relType(recv, from), f.name)
}
// writeSignature writes to buf the signature sig in declaration syntax.
func writeSignature(buf *bytes.Buffer, from *types.Package, name string, sig *types.Signature) {
buf.WriteString("func ")
if recv := sig.Recv(); recv != nil {
buf.WriteString("(")
if name := recv.Name(); name != "" {
buf.WriteString(name)
buf.WriteString(" ")
}
types.WriteType(buf, recv.Type(), types.RelativeTo(from))
buf.WriteString(") ")
}
buf.WriteString(name)
types.WriteSignature(buf, sig, types.RelativeTo(from))
}
func (f *Function) pkg() *types.Package {
if f.Pkg != nil {
return f.Pkg.Pkg
}
return nil
}
var _ io.WriterTo = (*Function)(nil) // *Function implements io.Writer
func (f *Function) WriteTo(w io.Writer) (int64, error) {
var buf bytes.Buffer
WriteFunction(&buf, f)
n, err := w.Write(buf.Bytes())
return int64(n), err
}
// WriteFunction writes to buf a human-readable "disassembly" of f.
func WriteFunction(buf *bytes.Buffer, f *Function) {
fmt.Fprintf(buf, "# Name: %s\n", f.String())
if f.Pkg != nil {
fmt.Fprintf(buf, "# Package: %s\n", f.Pkg.Pkg.Path())
}
if syn := f.Synthetic; syn != 0 {
fmt.Fprintln(buf, "# Synthetic:", syn)
}
if pos := f.Pos(); pos.IsValid() {
fmt.Fprintf(buf, "# Location: %s\n", f.Prog.Fset.Position(pos))
}
if f.parent != nil {
fmt.Fprintf(buf, "# Parent: %s\n", f.parent.Name())
}
from := f.pkg()
if f.FreeVars != nil {
buf.WriteString("# Free variables:\n")
for i, fv := range f.FreeVars {
fmt.Fprintf(buf, "# % 3d:\t%s %s\n", i, fv.Name(), relType(fv.Type(), from))
}
}
if len(f.Locals) > 0 {
buf.WriteString("# Locals:\n")
for i, l := range f.Locals {
fmt.Fprintf(buf, "# % 3d:\t%s %s\n", i, l.Name(), relType(deref(l.Type()), from))
}
}
writeSignature(buf, from, f.Name(), f.Signature)
buf.WriteString(":\n")
if f.Blocks == nil {
buf.WriteString("\t(external)\n")
}
for _, b := range f.Blocks {
if b == nil {
// Corrupt CFG.
fmt.Fprintf(buf, ".nil:\n")
continue
}
fmt.Fprintf(buf, "b%d:", b.Index)
if len(b.Preds) > 0 {
fmt.Fprint(buf, " ←")
for _, pred := range b.Preds {
fmt.Fprintf(buf, " b%d", pred.Index)
}
}
if b.Comment != "" {
fmt.Fprintf(buf, " # %s", b.Comment)
}
buf.WriteByte('\n')
if false { // CFG debugging
fmt.Fprintf(buf, "\t# CFG: %s --> %s --> %s\n", b.Preds, b, b.Succs)
}
buf2 := &bytes.Buffer{}
for _, instr := range b.Instrs {
buf.WriteString("\t")
switch v := instr.(type) {
case Value:
// Left-align the instruction.
if name := v.Name(); name != "" {
fmt.Fprintf(buf, "%s = ", name)
}
buf.WriteString(instr.String())
case nil:
// Be robust against bad transforms.
buf.WriteString("<deleted>")
default:
buf.WriteString(instr.String())
}
if instr != nil && instr.Comment() != "" {
buf.WriteString(" # ")
buf.WriteString(instr.Comment())
}
buf.WriteString("\n")
if f.Prog.mode&PrintSource != 0 {
if s := instr.Source(); s != nil {
buf2.Reset()
format.Node(buf2, f.Prog.Fset, s)
for {
line, err := buf2.ReadString('\n')
if len(line) == 0 {
break
}
buf.WriteString("\t\t> ")
buf.WriteString(line)
if line[len(line)-1] != '\n' {
buf.WriteString("\n")
}
if err != nil {
break
}
}
}
}
}
buf.WriteString("\n")
}
}
// newBasicBlock adds to f a new basic block and returns it. It does
// not automatically become the current block for subsequent calls to emit.
// comment is an optional string for more readable debugging output.
func (f *Function) newBasicBlock(comment string) *BasicBlock {
var instrs []Instruction
if len(f.functionBody.scratchInstructions) > 0 {
instrs = f.functionBody.scratchInstructions[0:0:avgInstructionsPerBlock]
f.functionBody.scratchInstructions = f.functionBody.scratchInstructions[avgInstructionsPerBlock:]
} else {
instrs = make([]Instruction, 0, avgInstructionsPerBlock)
}
b := &BasicBlock{
Index: len(f.Blocks),
Comment: comment,
parent: f,
Instrs: instrs,
}
b.Succs = b.succs2[:0]
f.Blocks = append(f.Blocks, b)
return b
}
// NewFunction returns a new synthetic Function instance belonging to
// prog, with its name and signature fields set as specified.
//
// The caller is responsible for initializing the remaining fields of
// the function object, e.g. Pkg, Params, Blocks.
//
// It is practically impossible for clients to construct well-formed
// IR functions/packages/programs directly, so we assume this is the
// job of the Builder alone. NewFunction exists to provide clients a
// little flexibility. For example, analysis tools may wish to
// construct fake Functions for the root of the callgraph, a fake
// "reflect" package, etc.
//
// TODO(adonovan): think harder about the API here.
func (prog *Program) NewFunction(name string, sig *types.Signature, provenance Synthetic) *Function {
return &Function{Prog: prog, name: name, Signature: sig, Synthetic: provenance}
}
//lint:ignore U1000 we may make use of this for functions loaded from export data
type extentNode [2]token.Pos
func (n extentNode) Pos() token.Pos { return n[0] }
func (n extentNode) End() token.Pos { return n[1] }
func (f *Function) initHTML(name string) {
if name == "" {
return
}
if rel := f.RelString(nil); rel == name {
f.wr = NewHTMLWriter("ir.html", rel, "")
}