1//===-- llvm/MC/MCAsmInfo.h - Asm info --------------------------*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file contains a class to be used as the basis for target specific
11// asm writers.  This class primarily takes care of global printing constants,
12// which are used in very similar ways across all targets.
13//
14//===----------------------------------------------------------------------===//
15
16#ifndef LLVM_MC_MCASMINFO_H
17#define LLVM_MC_MCASMINFO_H
18
19#include "llvm/MC/MCDirectives.h"
20#include "llvm/MC/MCDwarf.h"
21#include "llvm/MC/MachineLocation.h"
22#include <cassert>
23#include <vector>
24
25namespace llvm {
26class MCExpr;
27class MCSection;
28class MCStreamer;
29class MCSymbol;
30class MCContext;
31
32namespace WinEH {
33enum class EncodingType {
34  ET_Invalid, /// Invalid
35  ET_Alpha,   /// Windows Alpha
36  ET_Alpha64, /// Windows AXP64
37  ET_ARM,     /// Windows NT (Windows on ARM)
38  ET_CE,      /// Windows CE ARM, PowerPC, SH3, SH4
39  ET_Itanium, /// Windows x64, Windows Itanium (IA-64)
40  ET_MIPS = ET_Alpha,
41};
42}
43
44enum class ExceptionHandling {
45  None,     /// No exception support
46  DwarfCFI, /// DWARF-like instruction based exceptions
47  SjLj,     /// setjmp/longjmp based exceptions
48  ARM,      /// ARM EHABI
49  WinEH,    /// Windows Exception Handling
50};
51
52namespace LCOMM {
53enum LCOMMType { NoAlignment, ByteAlignment, Log2Alignment };
54}
55
56/// This class is intended to be used as a base class for asm
57/// properties and features specific to the target.
58class MCAsmInfo {
59protected:
60  //===------------------------------------------------------------------===//
61  // Properties to be set by the target writer, used to configure asm printer.
62  //
63
64  /// Pointer size in bytes.  Default is 4.
65  unsigned PointerSize;
66
67  /// Size of the stack slot reserved for callee-saved registers, in bytes.
68  /// Default is same as pointer size.
69  unsigned CalleeSaveStackSlotSize;
70
71  /// True if target is little endian.  Default is true.
72  bool IsLittleEndian;
73
74  /// True if target stack grow up.  Default is false.
75  bool StackGrowsUp;
76
77  /// True if this target has the MachO .subsections_via_symbols directive.
78  /// Default is false.
79  bool HasSubsectionsViaSymbols;
80
81  /// True if this is a MachO target that supports the macho-specific .zerofill
82  /// directive for emitting BSS Symbols.  Default is false.
83  bool HasMachoZeroFillDirective;
84
85  /// True if this is a MachO target that supports the macho-specific .tbss
86  /// directive for emitting thread local BSS Symbols.  Default is false.
87  bool HasMachoTBSSDirective;
88
89  /// True if the compiler should emit a ".reference .constructors_used" or
90  /// ".reference .destructors_used" directive after the a static ctor/dtor
91  /// list.  This directive is only emitted in Static relocation model.  Default
92  /// is false.
93  bool HasStaticCtorDtorReferenceInStaticMode;
94
95  /// True if the linker has a bug and requires that the debug_line section be
96  /// of a minimum size. In practice such a linker requires a non-empty line
97  /// sequence if a file is present.  Default to false.
98  bool LinkerRequiresNonEmptyDwarfLines;
99
100  /// This is the maximum possible length of an instruction, which is needed to
101  /// compute the size of an inline asm.  Defaults to 4.
102  unsigned MaxInstLength;
103
104  /// Every possible instruction length is a multiple of this value.  Factored
105  /// out in .debug_frame and .debug_line.  Defaults to 1.
106  unsigned MinInstAlignment;
107
108  /// The '$' token, when not referencing an identifier or constant, refers to
109  /// the current PC.  Defaults to false.
110  bool DollarIsPC;
111
112  /// This string, if specified, is used to separate instructions from each
113  /// other when on the same line.  Defaults to ';'
114  const char *SeparatorString;
115
116  /// This indicates the comment character used by the assembler.  Defaults to
117  /// "#"
118  const char *CommentString;
119
120  /// This is appended to emitted labels.  Defaults to ":"
121  const char *LabelSuffix;
122
123  // Print the EH begin symbol with an assignment. Defaults to false.
124  bool UseAssignmentForEHBegin;
125
126  /// This prefix is used for globals like constant pool entries that are
127  /// completely private to the .s file and should not have names in the .o
128  /// file.  Defaults to "L"
129  const char *PrivateGlobalPrefix;
130
131  /// This prefix is used for symbols that should be passed through the
132  /// assembler but be removed by the linker.  This is 'l' on Darwin, currently
133  /// used for some ObjC metadata.  The default of "" meast that for this system
134  /// a plain private symbol should be used.  Defaults to "".
135  const char *LinkerPrivateGlobalPrefix;
136
137  /// If these are nonempty, they contain a directive to emit before and after
138  /// an inline assembly statement.  Defaults to "#APP\n", "#NO_APP\n"
139  const char *InlineAsmStart;
140  const char *InlineAsmEnd;
141
142  /// These are assembly directives that tells the assembler to interpret the
143  /// following instructions differently.  Defaults to ".code16", ".code32",
144  /// ".code64".
145  const char *Code16Directive;
146  const char *Code32Directive;
147  const char *Code64Directive;
148
149  /// Which dialect of an assembler variant to use.  Defaults to 0
150  unsigned AssemblerDialect;
151
152  /// This is true if the assembler allows @ characters in symbol names.
153  /// Defaults to false.
154  bool AllowAtInName;
155
156  /// This is true if data region markers should be printed as
157  /// ".data_region/.end_data_region" directives. If false, use "$d/$a" labels
158  /// instead.
159  bool UseDataRegionDirectives;
160
161  //===--- Data Emission Directives -------------------------------------===//
162
163  /// This should be set to the directive used to get some number of zero bytes
164  /// emitted to the current section.  Common cases are "\t.zero\t" and
165  /// "\t.space\t".  If this is set to null, the Data*bitsDirective's will be
166  /// used to emit zero bytes.  Defaults to "\t.zero\t"
167  const char *ZeroDirective;
168
169  /// This directive allows emission of an ascii string with the standard C
170  /// escape characters embedded into it.  Defaults to "\t.ascii\t"
171  const char *AsciiDirective;
172
173  /// If not null, this allows for special handling of zero terminated strings
174  /// on this target.  This is commonly supported as ".asciz".  If a target
175  /// doesn't support this, it can be set to null.  Defaults to "\t.asciz\t"
176  const char *AscizDirective;
177
178  /// These directives are used to output some unit of integer data to the
179  /// current section.  If a data directive is set to null, smaller data
180  /// directives will be used to emit the large sizes.  Defaults to "\t.byte\t",
181  /// "\t.short\t", "\t.long\t", "\t.quad\t"
182  const char *Data8bitsDirective;
183  const char *Data16bitsDirective;
184  const char *Data32bitsDirective;
185  const char *Data64bitsDirective;
186
187  /// If non-null, a directive that is used to emit a word which should be
188  /// relocated as a 64-bit GP-relative offset, e.g. .gpdword on Mips.  Defaults
189  /// to NULL.
190  const char *GPRel64Directive;
191
192  /// If non-null, a directive that is used to emit a word which should be
193  /// relocated as a 32-bit GP-relative offset, e.g. .gpword on Mips or .gprel32
194  /// on Alpha.  Defaults to NULL.
195  const char *GPRel32Directive;
196
197  /// This is true if this target uses "Sun Style" syntax for section switching
198  /// ("#alloc,#write" etc) instead of the normal ELF syntax (,"a,w") in
199  /// .section directives.  Defaults to false.
200  bool SunStyleELFSectionSwitchSyntax;
201
202  /// This is true if this target uses ELF '.section' directive before the
203  /// '.bss' one. It's used for PPC/Linux which doesn't support the '.bss'
204  /// directive only.  Defaults to false.
205  bool UsesELFSectionDirectiveForBSS;
206
207  bool NeedsDwarfSectionOffsetDirective;
208
209  //===--- Alignment Information ----------------------------------------===//
210
211  /// If this is true (the default) then the asmprinter emits ".align N"
212  /// directives, where N is the number of bytes to align to.  Otherwise, it
213  /// emits ".align log2(N)", e.g. 3 to align to an 8 byte boundary.  Defaults
214  /// to true.
215  bool AlignmentIsInBytes;
216
217  /// If non-zero, this is used to fill the executable space created as the
218  /// result of a alignment directive.  Defaults to 0
219  unsigned TextAlignFillValue;
220
221  //===--- Global Variable Emission Directives --------------------------===//
222
223  /// This is the directive used to declare a global entity.  Defaults to NULL.
224  const char *GlobalDirective;
225
226  /// True if the assembler supports the .set directive.  Defaults to true.
227  bool HasSetDirective;
228
229  /// False if the assembler requires that we use
230  /// \code
231  ///   Lc = a - b
232  ///   .long Lc
233  /// \endcode
234  //
235  /// instead of
236  //
237  /// \code
238  ///   .long a - b
239  /// \endcode
240  ///
241  ///  Defaults to true.
242  bool HasAggressiveSymbolFolding;
243
244  /// True is .comm's and .lcomms optional alignment is to be specified in bytes
245  /// instead of log2(n).  Defaults to true.
246  bool COMMDirectiveAlignmentIsInBytes;
247
248  /// Describes if the .lcomm directive for the target supports an alignment
249  /// argument and how it is interpreted.  Defaults to NoAlignment.
250  LCOMM::LCOMMType LCOMMDirectiveAlignmentType;
251
252  /// True if the target has .type and .size directives, this is true for most
253  /// ELF targets.  Defaults to true.
254  bool HasDotTypeDotSizeDirective;
255
256  /// True if the target has a single parameter .file directive, this is true
257  /// for ELF targets.  Defaults to true.
258  bool HasSingleParameterDotFile;
259
260  /// True if the target has a .ident directive, this is true for ELF targets.
261  /// Defaults to false.
262  bool HasIdentDirective;
263
264  /// True if this target supports the MachO .no_dead_strip directive.  Defaults
265  /// to false.
266  bool HasNoDeadStrip;
267
268  /// This directive, if non-null, is used to declare a global as being a weak
269  /// undefined symbol.  Defaults to NULL.
270  const char *WeakRefDirective;
271
272  /// True if we have a directive to declare a global as being a weak defined
273  /// symbol.  Defaults to false.
274  bool HasWeakDefDirective;
275
276  /// True if we have a directive to declare a global as being a weak defined
277  /// symbol that can be hidden (unexported).  Defaults to false.
278  bool HasWeakDefCanBeHiddenDirective;
279
280  /// True if we have a .linkonce directive.  This is used on cygwin/mingw.
281  /// Defaults to false.
282  bool HasLinkOnceDirective;
283
284  /// This attribute, if not MCSA_Invalid, is used to declare a symbol as having
285  /// hidden visibility.  Defaults to MCSA_Hidden.
286  MCSymbolAttr HiddenVisibilityAttr;
287
288  /// This attribute, if not MCSA_Invalid, is used to declare an undefined
289  /// symbol as having hidden visibility. Defaults to MCSA_Hidden.
290  MCSymbolAttr HiddenDeclarationVisibilityAttr;
291
292  /// This attribute, if not MCSA_Invalid, is used to declare a symbol as having
293  /// protected visibility.  Defaults to MCSA_Protected
294  MCSymbolAttr ProtectedVisibilityAttr;
295
296  //===--- Dwarf Emission Directives -----------------------------------===//
297
298  /// True if target asm supports leb128 directives.  Defaults to false.
299  bool HasLEB128;
300
301  /// True if target supports emission of debugging information.  Defaults to
302  /// false.
303  bool SupportsDebugInformation;
304
305  /// Exception handling format for the target.  Defaults to None.
306  ExceptionHandling ExceptionsType;
307
308  /// Windows exception handling data (.pdata) encoding.  Defaults to Invalid.
309  WinEH::EncodingType WinEHEncodingType;
310
311  /// True if Dwarf2 output generally uses relocations for references to other
312  /// .debug_* sections.
313  bool DwarfUsesRelocationsAcrossSections;
314
315  /// True if DWARF FDE symbol reference relocations should be replaced by an
316  /// absolute difference.
317  bool DwarfFDESymbolsUseAbsDiff;
318
319  /// True if dwarf register numbers are printed instead of symbolic register
320  /// names in .cfi_* directives.  Defaults to false.
321  bool DwarfRegNumForCFI;
322
323  /// True if target uses parens to indicate the symbol variant instead of @.
324  /// For example, foo(plt) instead of foo@plt.  Defaults to false.
325  bool UseParensForSymbolVariant;
326
327  //===--- Prologue State ----------------------------------------------===//
328
329  std::vector<MCCFIInstruction> InitialFrameState;
330
331  //===--- Integrated Assembler State ----------------------------------===//
332
333  /// Should we use the integrated assembler?
334  /// The integrated assembler should be enabled by default (by the
335  /// constructors) when failing to parse a valid piece of assembly (inline
336  /// or otherwise) is considered a bug. It may then be overridden after
337  /// construction (see LLVMTargetMachine::initAsmInfo()).
338  bool UseIntegratedAssembler;
339
340  /// Compress DWARF debug sections. Defaults to false.
341  bool CompressDebugSections;
342
343public:
344  explicit MCAsmInfo();
345  virtual ~MCAsmInfo();
346
347  /// Get the pointer size in bytes.
348  unsigned getPointerSize() const { return PointerSize; }
349
350  /// Get the callee-saved register stack slot
351  /// size in bytes.
352  unsigned getCalleeSaveStackSlotSize() const {
353    return CalleeSaveStackSlotSize;
354  }
355
356  /// True if the target is little endian.
357  bool isLittleEndian() const { return IsLittleEndian; }
358
359  /// True if target stack grow up.
360  bool isStackGrowthDirectionUp() const { return StackGrowsUp; }
361
362  bool hasSubsectionsViaSymbols() const { return HasSubsectionsViaSymbols; }
363
364  // Data directive accessors.
365
366  const char *getData8bitsDirective() const { return Data8bitsDirective; }
367  const char *getData16bitsDirective() const { return Data16bitsDirective; }
368  const char *getData32bitsDirective() const { return Data32bitsDirective; }
369  const char *getData64bitsDirective() const { return Data64bitsDirective; }
370  const char *getGPRel64Directive() const { return GPRel64Directive; }
371  const char *getGPRel32Directive() const { return GPRel32Directive; }
372
373  /// Targets can implement this method to specify a section to switch to if the
374  /// translation unit doesn't have any trampolines that require an executable
375  /// stack.
376  virtual const MCSection *getNonexecutableStackSection(MCContext &Ctx) const {
377    return nullptr;
378  }
379
380  virtual const MCExpr *getExprForPersonalitySymbol(const MCSymbol *Sym,
381                                                    unsigned Encoding,
382                                                    MCStreamer &Streamer) const;
383
384  virtual const MCExpr *getExprForFDESymbol(const MCSymbol *Sym,
385                                            unsigned Encoding,
386                                            MCStreamer &Streamer) const;
387
388  bool usesSunStyleELFSectionSwitchSyntax() const {
389    return SunStyleELFSectionSwitchSyntax;
390  }
391
392  bool usesELFSectionDirectiveForBSS() const {
393    return UsesELFSectionDirectiveForBSS;
394  }
395
396  bool needsDwarfSectionOffsetDirective() const {
397    return NeedsDwarfSectionOffsetDirective;
398  }
399
400  // Accessors.
401
402  bool hasMachoZeroFillDirective() const { return HasMachoZeroFillDirective; }
403  bool hasMachoTBSSDirective() const { return HasMachoTBSSDirective; }
404  bool hasStaticCtorDtorReferenceInStaticMode() const {
405    return HasStaticCtorDtorReferenceInStaticMode;
406  }
407  bool getLinkerRequiresNonEmptyDwarfLines() const {
408    return LinkerRequiresNonEmptyDwarfLines;
409  }
410  unsigned getMaxInstLength() const { return MaxInstLength; }
411  unsigned getMinInstAlignment() const { return MinInstAlignment; }
412  bool getDollarIsPC() const { return DollarIsPC; }
413  const char *getSeparatorString() const { return SeparatorString; }
414
415  /// This indicates the column (zero-based) at which asm comments should be
416  /// printed.
417  unsigned getCommentColumn() const { return 40; }
418
419  const char *getCommentString() const { return CommentString; }
420  const char *getLabelSuffix() const { return LabelSuffix; }
421
422  bool useAssignmentForEHBegin() const { return UseAssignmentForEHBegin; }
423  const char *getPrivateGlobalPrefix() const { return PrivateGlobalPrefix; }
424  bool hasLinkerPrivateGlobalPrefix() const {
425    return LinkerPrivateGlobalPrefix[0] != '\0';
426  }
427  const char *getLinkerPrivateGlobalPrefix() const {
428    if (hasLinkerPrivateGlobalPrefix())
429      return LinkerPrivateGlobalPrefix;
430    return getPrivateGlobalPrefix();
431  }
432  const char *getInlineAsmStart() const { return InlineAsmStart; }
433  const char *getInlineAsmEnd() const { return InlineAsmEnd; }
434  const char *getCode16Directive() const { return Code16Directive; }
435  const char *getCode32Directive() const { return Code32Directive; }
436  const char *getCode64Directive() const { return Code64Directive; }
437  unsigned getAssemblerDialect() const { return AssemblerDialect; }
438  bool doesAllowAtInName() const { return AllowAtInName; }
439  bool doesSupportDataRegionDirectives() const {
440    return UseDataRegionDirectives;
441  }
442  const char *getZeroDirective() const { return ZeroDirective; }
443  const char *getAsciiDirective() const { return AsciiDirective; }
444  const char *getAscizDirective() const { return AscizDirective; }
445  bool getAlignmentIsInBytes() const { return AlignmentIsInBytes; }
446  unsigned getTextAlignFillValue() const { return TextAlignFillValue; }
447  const char *getGlobalDirective() const { return GlobalDirective; }
448  bool hasSetDirective() const { return HasSetDirective; }
449  bool hasAggressiveSymbolFolding() const { return HasAggressiveSymbolFolding; }
450  bool getCOMMDirectiveAlignmentIsInBytes() const {
451    return COMMDirectiveAlignmentIsInBytes;
452  }
453  LCOMM::LCOMMType getLCOMMDirectiveAlignmentType() const {
454    return LCOMMDirectiveAlignmentType;
455  }
456  bool hasDotTypeDotSizeDirective() const { return HasDotTypeDotSizeDirective; }
457  bool hasSingleParameterDotFile() const { return HasSingleParameterDotFile; }
458  bool hasIdentDirective() const { return HasIdentDirective; }
459  bool hasNoDeadStrip() const { return HasNoDeadStrip; }
460  const char *getWeakRefDirective() const { return WeakRefDirective; }
461  bool hasWeakDefDirective() const { return HasWeakDefDirective; }
462  bool hasWeakDefCanBeHiddenDirective() const {
463    return HasWeakDefCanBeHiddenDirective;
464  }
465  bool hasLinkOnceDirective() const { return HasLinkOnceDirective; }
466
467  MCSymbolAttr getHiddenVisibilityAttr() const { return HiddenVisibilityAttr; }
468  MCSymbolAttr getHiddenDeclarationVisibilityAttr() const {
469    return HiddenDeclarationVisibilityAttr;
470  }
471  MCSymbolAttr getProtectedVisibilityAttr() const {
472    return ProtectedVisibilityAttr;
473  }
474  bool hasLEB128() const { return HasLEB128; }
475  bool doesSupportDebugInformation() const { return SupportsDebugInformation; }
476  bool doesSupportExceptionHandling() const {
477    return ExceptionsType != ExceptionHandling::None;
478  }
479  ExceptionHandling getExceptionHandlingType() const { return ExceptionsType; }
480  WinEH::EncodingType getWinEHEncodingType() const { return WinEHEncodingType; }
481  bool isExceptionHandlingDwarf() const {
482    return (ExceptionsType == ExceptionHandling::DwarfCFI ||
483            ExceptionsType == ExceptionHandling::ARM ||
484            // Windows handler data still uses DWARF LSDA encoding.
485            ExceptionsType == ExceptionHandling::WinEH);
486  }
487  bool doesDwarfUseRelocationsAcrossSections() const {
488    return DwarfUsesRelocationsAcrossSections;
489  }
490  bool doDwarfFDESymbolsUseAbsDiff() const { return DwarfFDESymbolsUseAbsDiff; }
491  bool useDwarfRegNumForCFI() const { return DwarfRegNumForCFI; }
492  bool useParensForSymbolVariant() const { return UseParensForSymbolVariant; }
493
494  void addInitialFrameState(const MCCFIInstruction &Inst) {
495    InitialFrameState.push_back(Inst);
496  }
497
498  const std::vector<MCCFIInstruction> &getInitialFrameState() const {
499    return InitialFrameState;
500  }
501
502  /// Return true if assembly (inline or otherwise) should be parsed.
503  bool useIntegratedAssembler() const { return UseIntegratedAssembler; }
504
505  /// Set whether assembly (inline or otherwise) should be parsed.
506  virtual void setUseIntegratedAssembler(bool Value) {
507    UseIntegratedAssembler = Value;
508  }
509
510  bool compressDebugSections() const { return CompressDebugSections; }
511
512  void setCompressDebugSections(bool CompressDebugSections) {
513    this->CompressDebugSections = CompressDebugSections;
514  }
515};
516}
517
518#endif
519