1//===- MCFragment.h - Fragment type hierarchy -------------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#ifndef LLVM_MC_MCFRAGMENT_H
10#define LLVM_MC_MCFRAGMENT_H
11
12#include "llvm/ADT/ArrayRef.h"
13#include "llvm/ADT/SmallString.h"
14#include "llvm/ADT/SmallVector.h"
15#include "llvm/ADT/StringRef.h"
16#include "llvm/ADT/ilist_node.h"
17#include "llvm/MC/MCFixup.h"
18#include "llvm/MC/MCInst.h"
19#include "llvm/Support/Alignment.h"
20#include "llvm/Support/Casting.h"
21#include "llvm/Support/SMLoc.h"
22#include <cstdint>
23#include <utility>
24
25namespace llvm {
26
27class MCSection;
28class MCSubtargetInfo;
29class MCSymbol;
30
31class MCFragment : public ilist_node_with_parent<MCFragment, MCSection> {
32  friend class MCAsmLayout;
33
34public:
35  enum FragmentType : uint8_t {
36    FT_Align,
37    FT_Data,
38    FT_CompactEncodedInst,
39    FT_Fill,
40    FT_Relaxable,
41    FT_Org,
42    FT_Dwarf,
43    FT_DwarfFrame,
44    FT_LEB,
45    FT_BoundaryAlign,
46    FT_SymbolId,
47    FT_CVInlineLines,
48    FT_CVDefRange,
49    FT_Dummy
50  };
51
52private:
53  /// The data for the section this fragment is in.
54  MCSection *Parent;
55
56  /// The atom this fragment is in, as represented by its defining symbol.
57  const MCSymbol *Atom;
58
59  /// The offset of this fragment in its section. This is ~0 until
60  /// initialized.
61  uint64_t Offset;
62
63  /// The layout order of this fragment.
64  unsigned LayoutOrder;
65
66  FragmentType Kind;
67
68  /// Whether fragment is being laid out.
69  bool IsBeingLaidOut;
70
71protected:
72  bool HasInstructions;
73
74  MCFragment(FragmentType Kind, bool HasInstructions,
75             MCSection *Parent = nullptr);
76
77public:
78  MCFragment() = delete;
79  MCFragment(const MCFragment &) = delete;
80  MCFragment &operator=(const MCFragment &) = delete;
81
82  /// Destroys the current fragment.
83  ///
84  /// This must be used instead of delete as MCFragment is non-virtual.
85  /// This method will dispatch to the appropriate subclass.
86  void destroy();
87
88  FragmentType getKind() const { return Kind; }
89
90  MCSection *getParent() const { return Parent; }
91  void setParent(MCSection *Value) { Parent = Value; }
92
93  const MCSymbol *getAtom() const { return Atom; }
94  void setAtom(const MCSymbol *Value) { Atom = Value; }
95
96  unsigned getLayoutOrder() const { return LayoutOrder; }
97  void setLayoutOrder(unsigned Value) { LayoutOrder = Value; }
98
99  /// Does this fragment have instructions emitted into it? By default
100  /// this is false, but specific fragment types may set it to true.
101  bool hasInstructions() const { return HasInstructions; }
102
103  void dump() const;
104};
105
106class MCDummyFragment : public MCFragment {
107public:
108  explicit MCDummyFragment(MCSection *Sec) : MCFragment(FT_Dummy, false, Sec) {}
109
110  static bool classof(const MCFragment *F) { return F->getKind() == FT_Dummy; }
111};
112
113/// Interface implemented by fragments that contain encoded instructions and/or
114/// data.
115///
116class MCEncodedFragment : public MCFragment {
117  /// Should this fragment be aligned to the end of a bundle?
118  bool AlignToBundleEnd = false;
119
120  uint8_t BundlePadding = 0;
121
122protected:
123  MCEncodedFragment(MCFragment::FragmentType FType, bool HasInstructions,
124                    MCSection *Sec)
125      : MCFragment(FType, HasInstructions, Sec) {}
126
127  /// The MCSubtargetInfo in effect when the instruction was encoded.
128  /// It must be non-null for instructions.
129  const MCSubtargetInfo *STI = nullptr;
130
131public:
132  static bool classof(const MCFragment *F) {
133    MCFragment::FragmentType Kind = F->getKind();
134    switch (Kind) {
135    default:
136      return false;
137    case MCFragment::FT_Relaxable:
138    case MCFragment::FT_CompactEncodedInst:
139    case MCFragment::FT_Data:
140    case MCFragment::FT_Dwarf:
141    case MCFragment::FT_DwarfFrame:
142      return true;
143    }
144  }
145
146  /// Should this fragment be placed at the end of an aligned bundle?
147  bool alignToBundleEnd() const { return AlignToBundleEnd; }
148  void setAlignToBundleEnd(bool V) { AlignToBundleEnd = V; }
149
150  /// Get the padding size that must be inserted before this fragment.
151  /// Used for bundling. By default, no padding is inserted.
152  /// Note that padding size is restricted to 8 bits. This is an optimization
153  /// to reduce the amount of space used for each fragment. In practice, larger
154  /// padding should never be required.
155  uint8_t getBundlePadding() const { return BundlePadding; }
156
157  /// Set the padding size for this fragment. By default it's a no-op,
158  /// and only some fragments have a meaningful implementation.
159  void setBundlePadding(uint8_t N) { BundlePadding = N; }
160
161  /// Retrieve the MCSubTargetInfo in effect when the instruction was encoded.
162  /// Guaranteed to be non-null if hasInstructions() == true
163  const MCSubtargetInfo *getSubtargetInfo() const { return STI; }
164
165  /// Record that the fragment contains instructions with the MCSubtargetInfo in
166  /// effect when the instruction was encoded.
167  void setHasInstructions(const MCSubtargetInfo &STI) {
168    HasInstructions = true;
169    this->STI = &STI;
170  }
171};
172
173/// Interface implemented by fragments that contain encoded instructions and/or
174/// data.
175///
176template<unsigned ContentsSize>
177class MCEncodedFragmentWithContents : public MCEncodedFragment {
178  SmallVector<char, ContentsSize> Contents;
179
180protected:
181  MCEncodedFragmentWithContents(MCFragment::FragmentType FType,
182                                bool HasInstructions,
183                                MCSection *Sec)
184      : MCEncodedFragment(FType, HasInstructions, Sec) {}
185
186public:
187  SmallVectorImpl<char> &getContents() { return Contents; }
188  const SmallVectorImpl<char> &getContents() const { return Contents; }
189};
190
191/// Interface implemented by fragments that contain encoded instructions and/or
192/// data and also have fixups registered.
193///
194template<unsigned ContentsSize, unsigned FixupsSize>
195class MCEncodedFragmentWithFixups :
196  public MCEncodedFragmentWithContents<ContentsSize> {
197
198  /// The list of fixups in this fragment.
199  SmallVector<MCFixup, FixupsSize> Fixups;
200
201protected:
202  MCEncodedFragmentWithFixups(MCFragment::FragmentType FType,
203                              bool HasInstructions,
204                              MCSection *Sec)
205      : MCEncodedFragmentWithContents<ContentsSize>(FType, HasInstructions,
206                                                    Sec) {}
207
208public:
209
210  using const_fixup_iterator = SmallVectorImpl<MCFixup>::const_iterator;
211  using fixup_iterator = SmallVectorImpl<MCFixup>::iterator;
212
213  SmallVectorImpl<MCFixup> &getFixups() { return Fixups; }
214  const SmallVectorImpl<MCFixup> &getFixups() const { return Fixups; }
215
216  fixup_iterator fixup_begin() { return Fixups.begin(); }
217  const_fixup_iterator fixup_begin() const { return Fixups.begin(); }
218
219  fixup_iterator fixup_end() { return Fixups.end(); }
220  const_fixup_iterator fixup_end() const { return Fixups.end(); }
221
222  static bool classof(const MCFragment *F) {
223    MCFragment::FragmentType Kind = F->getKind();
224    return Kind == MCFragment::FT_Relaxable || Kind == MCFragment::FT_Data ||
225           Kind == MCFragment::FT_CVDefRange || Kind == MCFragment::FT_Dwarf ||
226           Kind == MCFragment::FT_DwarfFrame;
227  }
228};
229
230/// Fragment for data and encoded instructions.
231///
232class MCDataFragment : public MCEncodedFragmentWithFixups<32, 4> {
233public:
234  MCDataFragment(MCSection *Sec = nullptr)
235      : MCEncodedFragmentWithFixups<32, 4>(FT_Data, false, Sec) {}
236
237  static bool classof(const MCFragment *F) {
238    return F->getKind() == MCFragment::FT_Data;
239  }
240};
241
242/// This is a compact (memory-size-wise) fragment for holding an encoded
243/// instruction (non-relaxable) that has no fixups registered. When applicable,
244/// it can be used instead of MCDataFragment and lead to lower memory
245/// consumption.
246///
247class MCCompactEncodedInstFragment : public MCEncodedFragmentWithContents<4> {
248public:
249  MCCompactEncodedInstFragment(MCSection *Sec = nullptr)
250      : MCEncodedFragmentWithContents(FT_CompactEncodedInst, true, Sec) {
251  }
252
253  static bool classof(const MCFragment *F) {
254    return F->getKind() == MCFragment::FT_CompactEncodedInst;
255  }
256};
257
258/// A relaxable fragment holds on to its MCInst, since it may need to be
259/// relaxed during the assembler layout and relaxation stage.
260///
261class MCRelaxableFragment : public MCEncodedFragmentWithFixups<8, 1> {
262
263  /// The instruction this is a fragment for.
264  MCInst Inst;
265  /// Can we auto pad the instruction?
266  bool AllowAutoPadding = false;
267
268public:
269  MCRelaxableFragment(const MCInst &Inst, const MCSubtargetInfo &STI,
270                      MCSection *Sec = nullptr)
271      : MCEncodedFragmentWithFixups(FT_Relaxable, true, Sec),
272        Inst(Inst) { this->STI = &STI; }
273
274  const MCInst &getInst() const { return Inst; }
275  void setInst(const MCInst &Value) { Inst = Value; }
276
277  bool getAllowAutoPadding() const { return AllowAutoPadding; }
278  void setAllowAutoPadding(bool V) { AllowAutoPadding = V; }
279
280  static bool classof(const MCFragment *F) {
281    return F->getKind() == MCFragment::FT_Relaxable;
282  }
283};
284
285class MCAlignFragment : public MCFragment {
286  /// The alignment to ensure, in bytes.
287  unsigned Alignment;
288
289  /// Flag to indicate that (optimal) NOPs should be emitted instead
290  /// of using the provided value. The exact interpretation of this flag is
291  /// target dependent.
292  bool EmitNops : 1;
293
294  /// Value to use for filling padding bytes.
295  int64_t Value;
296
297  /// The size of the integer (in bytes) of \p Value.
298  unsigned ValueSize;
299
300  /// The maximum number of bytes to emit; if the alignment
301  /// cannot be satisfied in this width then this fragment is ignored.
302  unsigned MaxBytesToEmit;
303
304public:
305  MCAlignFragment(unsigned Alignment, int64_t Value, unsigned ValueSize,
306                  unsigned MaxBytesToEmit, MCSection *Sec = nullptr)
307      : MCFragment(FT_Align, false, Sec), Alignment(Alignment), EmitNops(false),
308        Value(Value), ValueSize(ValueSize), MaxBytesToEmit(MaxBytesToEmit) {}
309
310  unsigned getAlignment() const { return Alignment; }
311
312  int64_t getValue() const { return Value; }
313
314  unsigned getValueSize() const { return ValueSize; }
315
316  unsigned getMaxBytesToEmit() const { return MaxBytesToEmit; }
317
318  bool hasEmitNops() const { return EmitNops; }
319  void setEmitNops(bool Value) { EmitNops = Value; }
320
321  static bool classof(const MCFragment *F) {
322    return F->getKind() == MCFragment::FT_Align;
323  }
324};
325
326class MCFillFragment : public MCFragment {
327  uint8_t ValueSize;
328  /// Value to use for filling bytes.
329  uint64_t Value;
330  /// The number of bytes to insert.
331  const MCExpr &NumValues;
332
333  /// Source location of the directive that this fragment was created for.
334  SMLoc Loc;
335
336public:
337  MCFillFragment(uint64_t Value, uint8_t VSize, const MCExpr &NumValues,
338                 SMLoc Loc, MCSection *Sec = nullptr)
339      : MCFragment(FT_Fill, false, Sec), ValueSize(VSize), Value(Value),
340        NumValues(NumValues), Loc(Loc) {}
341
342  uint64_t getValue() const { return Value; }
343  uint8_t getValueSize() const { return ValueSize; }
344  const MCExpr &getNumValues() const { return NumValues; }
345
346  SMLoc getLoc() const { return Loc; }
347
348  static bool classof(const MCFragment *F) {
349    return F->getKind() == MCFragment::FT_Fill;
350  }
351};
352
353class MCOrgFragment : public MCFragment {
354  /// Value to use for filling bytes.
355  int8_t Value;
356
357  /// The offset this fragment should start at.
358  const MCExpr *Offset;
359
360  /// Source location of the directive that this fragment was created for.
361  SMLoc Loc;
362
363public:
364  MCOrgFragment(const MCExpr &Offset, int8_t Value, SMLoc Loc,
365                MCSection *Sec = nullptr)
366      : MCFragment(FT_Org, false, Sec), Value(Value), Offset(&Offset),
367        Loc(Loc) {}
368
369  const MCExpr &getOffset() const { return *Offset; }
370
371  uint8_t getValue() const { return Value; }
372
373  SMLoc getLoc() const { return Loc; }
374
375  static bool classof(const MCFragment *F) {
376    return F->getKind() == MCFragment::FT_Org;
377  }
378};
379
380class MCLEBFragment : public MCFragment {
381  /// True if this is a sleb128, false if uleb128.
382  bool IsSigned;
383
384  /// The value this fragment should contain.
385  const MCExpr *Value;
386
387  SmallString<8> Contents;
388
389public:
390  MCLEBFragment(const MCExpr &Value_, bool IsSigned_, MCSection *Sec = nullptr)
391      : MCFragment(FT_LEB, false, Sec), IsSigned(IsSigned_), Value(&Value_) {
392    Contents.push_back(0);
393  }
394
395  const MCExpr &getValue() const { return *Value; }
396
397  bool isSigned() const { return IsSigned; }
398
399  SmallString<8> &getContents() { return Contents; }
400  const SmallString<8> &getContents() const { return Contents; }
401
402  /// @}
403
404  static bool classof(const MCFragment *F) {
405    return F->getKind() == MCFragment::FT_LEB;
406  }
407};
408
409class MCDwarfLineAddrFragment : public MCEncodedFragmentWithFixups<8, 1> {
410  /// The value of the difference between the two line numbers
411  /// between two .loc dwarf directives.
412  int64_t LineDelta;
413
414  /// The expression for the difference of the two symbols that
415  /// make up the address delta between two .loc dwarf directives.
416  const MCExpr *AddrDelta;
417
418public:
419  MCDwarfLineAddrFragment(int64_t LineDelta, const MCExpr &AddrDelta,
420                          MCSection *Sec = nullptr)
421      : MCEncodedFragmentWithFixups<8, 1>(FT_Dwarf, false, Sec),
422        LineDelta(LineDelta), AddrDelta(&AddrDelta) {}
423
424  int64_t getLineDelta() const { return LineDelta; }
425
426  const MCExpr &getAddrDelta() const { return *AddrDelta; }
427
428  static bool classof(const MCFragment *F) {
429    return F->getKind() == MCFragment::FT_Dwarf;
430  }
431};
432
433class MCDwarfCallFrameFragment : public MCEncodedFragmentWithFixups<8, 1> {
434  /// The expression for the difference of the two symbols that
435  /// make up the address delta between two .cfi_* dwarf directives.
436  const MCExpr *AddrDelta;
437
438public:
439  MCDwarfCallFrameFragment(const MCExpr &AddrDelta, MCSection *Sec = nullptr)
440      : MCEncodedFragmentWithFixups<8, 1>(FT_DwarfFrame, false, Sec),
441        AddrDelta(&AddrDelta) {}
442
443  const MCExpr &getAddrDelta() const { return *AddrDelta; }
444
445  static bool classof(const MCFragment *F) {
446    return F->getKind() == MCFragment::FT_DwarfFrame;
447  }
448};
449
450/// Represents a symbol table index fragment.
451class MCSymbolIdFragment : public MCFragment {
452  const MCSymbol *Sym;
453
454public:
455  MCSymbolIdFragment(const MCSymbol *Sym, MCSection *Sec = nullptr)
456      : MCFragment(FT_SymbolId, false, Sec), Sym(Sym) {}
457
458  const MCSymbol *getSymbol() { return Sym; }
459  const MCSymbol *getSymbol() const { return Sym; }
460
461  static bool classof(const MCFragment *F) {
462    return F->getKind() == MCFragment::FT_SymbolId;
463  }
464};
465
466/// Fragment representing the binary annotations produced by the
467/// .cv_inline_linetable directive.
468class MCCVInlineLineTableFragment : public MCFragment {
469  unsigned SiteFuncId;
470  unsigned StartFileId;
471  unsigned StartLineNum;
472  const MCSymbol *FnStartSym;
473  const MCSymbol *FnEndSym;
474  SmallString<8> Contents;
475
476  /// CodeViewContext has the real knowledge about this format, so let it access
477  /// our members.
478  friend class CodeViewContext;
479
480public:
481  MCCVInlineLineTableFragment(unsigned SiteFuncId, unsigned StartFileId,
482                              unsigned StartLineNum, const MCSymbol *FnStartSym,
483                              const MCSymbol *FnEndSym,
484                              MCSection *Sec = nullptr)
485      : MCFragment(FT_CVInlineLines, false, Sec), SiteFuncId(SiteFuncId),
486        StartFileId(StartFileId), StartLineNum(StartLineNum),
487        FnStartSym(FnStartSym), FnEndSym(FnEndSym) {}
488
489  const MCSymbol *getFnStartSym() const { return FnStartSym; }
490  const MCSymbol *getFnEndSym() const { return FnEndSym; }
491
492  SmallString<8> &getContents() { return Contents; }
493  const SmallString<8> &getContents() const { return Contents; }
494
495  static bool classof(const MCFragment *F) {
496    return F->getKind() == MCFragment::FT_CVInlineLines;
497  }
498};
499
500/// Fragment representing the .cv_def_range directive.
501class MCCVDefRangeFragment : public MCEncodedFragmentWithFixups<32, 4> {
502  SmallVector<std::pair<const MCSymbol *, const MCSymbol *>, 2> Ranges;
503  SmallString<32> FixedSizePortion;
504
505  /// CodeViewContext has the real knowledge about this format, so let it access
506  /// our members.
507  friend class CodeViewContext;
508
509public:
510  MCCVDefRangeFragment(
511      ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges,
512      StringRef FixedSizePortion, MCSection *Sec = nullptr)
513      : MCEncodedFragmentWithFixups<32, 4>(FT_CVDefRange, false, Sec),
514        Ranges(Ranges.begin(), Ranges.end()),
515        FixedSizePortion(FixedSizePortion) {}
516
517  ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> getRanges() const {
518    return Ranges;
519  }
520
521  StringRef getFixedSizePortion() const { return FixedSizePortion; }
522
523  static bool classof(const MCFragment *F) {
524    return F->getKind() == MCFragment::FT_CVDefRange;
525  }
526};
527
528/// Represents required padding such that a particular other set of fragments
529/// does not cross a particular power-of-two boundary. The other fragments must
530/// follow this one within the same section.
531class MCBoundaryAlignFragment : public MCFragment {
532  /// The alignment requirement of the branch to be aligned.
533  Align AlignBoundary;
534  /// The last fragment in the set of fragments to be aligned.
535  const MCFragment *LastFragment = nullptr;
536  /// The size of the fragment.  The size is lazily set during relaxation, and
537  /// is not meaningful before that.
538  uint64_t Size = 0;
539
540public:
541  MCBoundaryAlignFragment(Align AlignBoundary, MCSection *Sec = nullptr)
542      : MCFragment(FT_BoundaryAlign, false, Sec), AlignBoundary(AlignBoundary) {
543  }
544
545  uint64_t getSize() const { return Size; }
546  void setSize(uint64_t Value) { Size = Value; }
547
548  Align getAlignment() const { return AlignBoundary; }
549  void setAlignment(Align Value) { AlignBoundary = Value; }
550
551  const MCFragment *getLastFragment() const { return LastFragment; }
552  void setLastFragment(const MCFragment *F) {
553    assert(!F || getParent() == F->getParent());
554    LastFragment = F;
555  }
556
557  static bool classof(const MCFragment *F) {
558    return F->getKind() == MCFragment::FT_BoundaryAlign;
559  }
560};
561} // end namespace llvm
562
563#endif // LLVM_MC_MCFRAGMENT_H
564