MCAsmInfo.h revision dce4a407a24b04eebc6a376f8e62b41aaa7b071f 
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 {
26  class MCExpr;
27  class MCSection;
28  class MCStreamer;
29  class MCSymbol;
30  class MCContext;
31
32  namespace ExceptionHandling {
33    enum ExceptionsType { None, DwarfCFI, SjLj, ARM, Win64 };
34  }
35
36  namespace LCOMM {
37    enum LCOMMType { NoAlignment, ByteAlignment, Log2Alignment };
38  }
39
40  /// MCAsmInfo - This class is intended to be used as a base class for asm
41  /// properties and features specific to the target.
42  class MCAsmInfo {
43  protected:
44    //===------------------------------------------------------------------===//
45    // Properties to be set by the target writer, used to configure asm printer.
46    //
47
48    /// PointerSize - Pointer size in bytes.
49    ///               Default is 4.
50    unsigned PointerSize;
51
52    /// CalleeSaveStackSlotSize - Size of the stack slot reserved for
53    ///                           callee-saved registers, in bytes.
54    ///                           Default is same as pointer size.
55    unsigned CalleeSaveStackSlotSize;
56
57    /// IsLittleEndian - True if target is little endian.
58    ///                  Default is true.
59    bool IsLittleEndian;
60
61    /// StackGrowsUp - True if target stack grow up.
62    ///                Default is false.
63    bool StackGrowsUp;
64
65    /// HasSubsectionsViaSymbols - True if this target has the MachO
66    /// .subsections_via_symbols directive.
67    bool HasSubsectionsViaSymbols;           // Default is false.
68
69    /// HasMachoZeroFillDirective - True if this is a MachO target that supports
70    /// the macho-specific .zerofill directive for emitting BSS Symbols.
71    bool HasMachoZeroFillDirective;               // Default is false.
72
73    /// HasMachoTBSSDirective - True if this is a MachO target that supports
74    /// the macho-specific .tbss directive for emitting thread local BSS Symbols
75    bool HasMachoTBSSDirective;                 // Default is false.
76
77    /// HasStaticCtorDtorReferenceInStaticMode - True if the compiler should
78    /// emit a ".reference .constructors_used" or ".reference .destructors_used"
79    /// directive after the a static ctor/dtor list.  This directive is only
80    /// emitted in Static relocation model.
81    bool HasStaticCtorDtorReferenceInStaticMode;  // Default is false.
82
83    /// LinkerRequiresNonEmptyDwarfLines - True if the linker has a bug and
84    /// requires that the debug_line section be of a minimum size. In practice
85    /// such a linker requires a non-empty line sequence if a file is present.
86    bool LinkerRequiresNonEmptyDwarfLines; // Default to false.
87
88    /// MaxInstLength - This is the maximum possible length of an instruction,
89    /// which is needed to compute the size of an inline asm.
90    unsigned MaxInstLength;                  // Defaults to 4.
91
92    /// MinInstAlignment - Every possible instruction length is a multiple of
93    /// this value.  Factored out in .debug_frame and .debug_line.
94    unsigned MinInstAlignment;                  // Defaults to 1.
95
96    /// DollarIsPC - The '$' token, when not referencing an identifier or
97    /// constant, refers to the current PC.
98    bool DollarIsPC;                         // Defaults to false.
99
100    /// SeparatorString - This string, if specified, is used to separate
101    /// instructions from each other when on the same line.
102    const char *SeparatorString;             // Defaults to ';'
103
104    /// CommentString - This indicates the comment character used by the
105    /// assembler.
106    const char *CommentString;               // Defaults to "#"
107
108    /// LabelSuffix - This is appended to emitted labels.
109    const char *LabelSuffix;                 // Defaults to ":"
110
111    /// LabelSuffix - This is appended to emitted labels.
112    const char *DebugLabelSuffix;                 // Defaults to ":"
113
114    /// This prefix is used for globals like constant pool entries that are
115    /// completely private to the .s file and should not have names in the .o
116    /// file.
117    const char *PrivateGlobalPrefix;         // Defaults to "L"
118
119    /// This prefix is used for symbols that should be passed through the
120    /// assembler but be removed by the linker.  This is 'l' on Darwin,
121    /// currently used for some ObjC metadata.
122    /// The default of "" meast that for this system a plain private symbol
123    /// should be used.
124    const char *LinkerPrivateGlobalPrefix;    // Defaults to "".
125
126    /// InlineAsmStart/End - If these are nonempty, they contain a directive to
127    /// emit before and after an inline assembly statement.
128    const char *InlineAsmStart;              // Defaults to "#APP\n"
129    const char *InlineAsmEnd;                // Defaults to "#NO_APP\n"
130
131    /// Code16Directive, Code32Directive, Code64Directive - These are assembly
132    /// directives that tells the assembler to interpret the following
133    /// instructions differently.
134    const char *Code16Directive;             // Defaults to ".code16"
135    const char *Code32Directive;             // Defaults to ".code32"
136    const char *Code64Directive;             // Defaults to ".code64"
137
138    /// AssemblerDialect - Which dialect of an assembler variant to use.
139    unsigned AssemblerDialect;               // Defaults to 0
140
141    /// \brief This is true if the assembler allows @ characters in symbol
142    /// names. Defaults to false.
143    bool AllowAtInName;
144
145    /// UseDataRegionDirectives - This is true if data region markers should
146    /// be printed as ".data_region/.end_data_region" directives. If false,
147    /// use "$d/$a" labels instead.
148    bool UseDataRegionDirectives;
149
150    //===--- Data Emission Directives -------------------------------------===//
151
152    /// ZeroDirective - this should be set to the directive used to get some
153    /// number of zero bytes emitted to the current section.  Common cases are
154    /// "\t.zero\t" and "\t.space\t".  If this is set to null, the
155    /// Data*bitsDirective's will be used to emit zero bytes.
156    const char *ZeroDirective;               // Defaults to "\t.zero\t"
157
158    /// AsciiDirective - This directive allows emission of an ascii string with
159    /// the standard C escape characters embedded into it.
160    const char *AsciiDirective;              // Defaults to "\t.ascii\t"
161
162    /// AscizDirective - If not null, this allows for special handling of
163    /// zero terminated strings on this target.  This is commonly supported as
164    /// ".asciz".  If a target doesn't support this, it can be set to null.
165    const char *AscizDirective;              // Defaults to "\t.asciz\t"
166
167    /// DataDirectives - These directives are used to output some unit of
168    /// integer data to the current section.  If a data directive is set to
169    /// null, smaller data directives will be used to emit the large sizes.
170    const char *Data8bitsDirective;          // Defaults to "\t.byte\t"
171    const char *Data16bitsDirective;         // Defaults to "\t.short\t"
172    const char *Data32bitsDirective;         // Defaults to "\t.long\t"
173    const char *Data64bitsDirective;         // Defaults to "\t.quad\t"
174
175    /// GPRel64Directive - if non-null, a directive that is used to emit a word
176    /// which should be relocated as a 64-bit GP-relative offset, e.g. .gpdword
177    /// on Mips.
178    const char *GPRel64Directive;            // Defaults to NULL.
179
180    /// GPRel32Directive - if non-null, a directive that is used to emit a word
181    /// which should be relocated as a 32-bit GP-relative offset, e.g. .gpword
182    /// on Mips or .gprel32 on Alpha.
183    const char *GPRel32Directive;            // Defaults to NULL.
184
185    /// SunStyleELFSectionSwitchSyntax - This is true if this target uses "Sun
186    /// Style" syntax for section switching ("#alloc,#write" etc) instead of the
187    /// normal ELF syntax (,"a,w") in .section directives.
188    bool SunStyleELFSectionSwitchSyntax;     // Defaults to false.
189
190    /// UsesELFSectionDirectiveForBSS - This is true if this target uses ELF
191    /// '.section' directive before the '.bss' one. It's used for PPC/Linux
192    /// which doesn't support the '.bss' directive only.
193    bool UsesELFSectionDirectiveForBSS;      // Defaults to false.
194
195    bool NeedsDwarfSectionOffsetDirective;
196
197    //===--- Alignment Information ----------------------------------------===//
198
199    /// AlignmentIsInBytes - If this is true (the default) then the asmprinter
200    /// emits ".align N" directives, where N is the number of bytes to align to.
201    /// Otherwise, it emits ".align log2(N)", e.g. 3 to align to an 8 byte
202    /// boundary.
203    bool AlignmentIsInBytes;                 // Defaults to true
204
205    /// TextAlignFillValue - If non-zero, this is used to fill the executable
206    /// space created as the result of a alignment directive.
207    unsigned TextAlignFillValue;             // Defaults to 0
208
209    //===--- Global Variable Emission Directives --------------------------===//
210
211    /// GlobalDirective - This is the directive used to declare a global entity.
212    ///
213    const char *GlobalDirective;             // Defaults to NULL.
214
215    /// HasSetDirective - True if the assembler supports the .set directive.
216    bool HasSetDirective;                    // Defaults to true.
217
218    /// HasAggressiveSymbolFolding - False if the assembler requires that we use
219    /// Lc = a - b
220    /// .long Lc
221    /// instead of
222    /// .long a - b
223    bool HasAggressiveSymbolFolding;           // Defaults to true.
224
225    /// COMMDirectiveAlignmentIsInBytes - True is .comm's and .lcomms optional
226    /// alignment is to be specified in bytes instead of log2(n).
227    bool COMMDirectiveAlignmentIsInBytes;    // Defaults to true;
228
229    /// LCOMMDirectiveAlignment - Describes if the .lcomm directive for the
230    /// target supports an alignment argument and how it is interpreted.
231    LCOMM::LCOMMType LCOMMDirectiveAlignmentType; // Defaults to NoAlignment.
232
233    /// HasDotTypeDotSizeDirective - True if the target has .type and .size
234    /// directives, this is true for most ELF targets.
235    bool HasDotTypeDotSizeDirective;         // Defaults to true.
236
237    /// HasSingleParameterDotFile - True if the target has a single parameter
238    /// .file directive, this is true for ELF targets.
239    bool HasSingleParameterDotFile;          // Defaults to true.
240
241    /// hasIdentDirective - True if the target has a .ident directive, this is
242    /// true for ELF targets.
243    bool HasIdentDirective;                  // Defaults to false.
244
245    /// HasNoDeadStrip - True if this target supports the MachO .no_dead_strip
246    /// directive.
247    bool HasNoDeadStrip;                     // Defaults to false.
248
249    /// WeakRefDirective - This directive, if non-null, is used to declare a
250    /// global as being a weak undefined symbol.
251    const char *WeakRefDirective;            // Defaults to NULL.
252
253    /// True if we have a directive to declare a global as being a weak
254    /// defined symbol.
255    bool HasWeakDefDirective;                // Defaults to false.
256
257    /// True if we have a directive to declare a global as being a weak
258    /// defined symbol that can be hidden (unexported).
259    bool HasWeakDefCanBeHiddenDirective;     // Defaults to false.
260
261    /// True if we have a .linkonce directive.  This is used on cygwin/mingw.
262    bool HasLinkOnceDirective;               // Defaults to false.
263
264    /// HiddenVisibilityAttr - This attribute, if not MCSA_Invalid, is used to
265    /// declare a symbol as having hidden visibility.
266    MCSymbolAttr HiddenVisibilityAttr;       // Defaults to MCSA_Hidden.
267
268    /// HiddenDeclarationVisibilityAttr - This attribute, if not MCSA_Invalid,
269    /// is used to declare an undefined symbol as having hidden visibility.
270    MCSymbolAttr HiddenDeclarationVisibilityAttr;   // Defaults to MCSA_Hidden.
271
272
273    /// ProtectedVisibilityAttr - This attribute, if not MCSA_Invalid, is used
274    /// to declare a symbol as having protected visibility.
275    MCSymbolAttr ProtectedVisibilityAttr;    // Defaults to MCSA_Protected
276
277    //===--- Dwarf Emission Directives -----------------------------------===//
278
279    /// HasLEB128 - True if target asm supports leb128 directives.
280    bool HasLEB128;                          // Defaults to false.
281
282    /// SupportsDebugInformation - True if target supports emission of debugging
283    /// information.
284    bool SupportsDebugInformation;           // Defaults to false.
285
286    /// SupportsExceptionHandling - True if target supports exception handling.
287    ExceptionHandling::ExceptionsType ExceptionsType; // Defaults to None
288
289    /// DwarfUsesRelocationsAcrossSections - True if Dwarf2 output generally
290    /// uses relocations for references to other .debug_* sections.
291    bool DwarfUsesRelocationsAcrossSections;
292
293    /// DwarfFDESymbolsUseAbsDiff - true if DWARF FDE symbol reference
294    /// relocations should be replaced by an absolute difference.
295    bool DwarfFDESymbolsUseAbsDiff;
296
297    /// DwarfRegNumForCFI - True if dwarf register numbers are printed
298    /// instead of symbolic register names in .cfi_* directives.
299    bool DwarfRegNumForCFI;  // Defaults to false;
300
301    /// UseParensForSymbolVariant - True if target uses parens to indicate the
302    /// symbol variant instead of @. For example, foo(plt) instead of foo@plt.
303    bool UseParensForSymbolVariant; // Defaults to false;
304
305    //===--- Prologue State ----------------------------------------------===//
306
307    std::vector<MCCFIInstruction> InitialFrameState;
308
309    //===--- Integrated Assembler State ----------------------------------===//
310    /// Should we use the integrated assembler?
311    /// The integrated assembler should be enabled by default (by the
312    /// constructors) when failing to parse a valid piece of assembly (inline
313    /// or otherwise) is considered a bug. It may then be overridden after
314    /// construction (see LLVMTargetMachine::initAsmInfo()).
315    bool UseIntegratedAssembler;
316
317    /// Compress DWARF debug sections. Defaults to false.
318    bool CompressDebugSections;
319
320  public:
321    explicit MCAsmInfo();
322    virtual ~MCAsmInfo();
323
324    /// getPointerSize - Get the pointer size in bytes.
325    unsigned getPointerSize() const {
326      return PointerSize;
327    }
328
329    /// getCalleeSaveStackSlotSize - Get the callee-saved register stack slot
330    /// size in bytes.
331    unsigned getCalleeSaveStackSlotSize() const {
332      return CalleeSaveStackSlotSize;
333    }
334
335    /// isLittleEndian - True if the target is little endian.
336    bool isLittleEndian() const {
337      return IsLittleEndian;
338    }
339
340    /// isStackGrowthDirectionUp - True if target stack grow up.
341    bool isStackGrowthDirectionUp() const {
342      return StackGrowsUp;
343    }
344
345    bool hasSubsectionsViaSymbols() const { return HasSubsectionsViaSymbols; }
346
347    // Data directive accessors.
348    //
349    const char *getData8bitsDirective() const {
350      return Data8bitsDirective;
351    }
352    const char *getData16bitsDirective() const {
353      return Data16bitsDirective;
354    }
355    const char *getData32bitsDirective() const {
356      return Data32bitsDirective;
357    }
358    const char *getData64bitsDirective() const {
359      return Data64bitsDirective;
360    }
361    const char *getGPRel64Directive() const { return GPRel64Directive; }
362    const char *getGPRel32Directive() const { return GPRel32Directive; }
363
364    /// getNonexecutableStackSection - Targets can implement this method to
365    /// specify a section to switch to if the translation unit doesn't have any
366    /// trampolines that require an executable stack.
367    virtual const MCSection *getNonexecutableStackSection(MCContext &Ctx) const{
368      return nullptr;
369    }
370
371    virtual const MCExpr *
372    getExprForPersonalitySymbol(const MCSymbol *Sym,
373                                unsigned Encoding,
374                                MCStreamer &Streamer) const;
375
376    virtual const MCExpr *
377    getExprForFDESymbol(const MCSymbol *Sym,
378                        unsigned Encoding,
379                        MCStreamer &Streamer) const;
380
381    bool usesSunStyleELFSectionSwitchSyntax() const {
382      return SunStyleELFSectionSwitchSyntax;
383    }
384
385    bool usesELFSectionDirectiveForBSS() const {
386      return UsesELFSectionDirectiveForBSS;
387    }
388
389    bool needsDwarfSectionOffsetDirective() const {
390      return NeedsDwarfSectionOffsetDirective;
391    }
392
393    // Accessors.
394    //
395    bool hasMachoZeroFillDirective() const { return HasMachoZeroFillDirective; }
396    bool hasMachoTBSSDirective() const { return HasMachoTBSSDirective; }
397    bool hasStaticCtorDtorReferenceInStaticMode() const {
398      return HasStaticCtorDtorReferenceInStaticMode;
399    }
400    bool getLinkerRequiresNonEmptyDwarfLines() const {
401      return LinkerRequiresNonEmptyDwarfLines;
402    }
403    unsigned getMaxInstLength() const {
404      return MaxInstLength;
405    }
406    unsigned getMinInstAlignment() const {
407      return MinInstAlignment;
408    }
409    bool getDollarIsPC() const {
410      return DollarIsPC;
411    }
412    const char *getSeparatorString() const {
413      return SeparatorString;
414    }
415
416    /// This indicates the column (zero-based) at which asm comments should be
417    /// printed.
418    unsigned getCommentColumn() const {
419      return 40;
420    }
421
422    const char *getCommentString() const {
423      return CommentString;
424    }
425    const char *getLabelSuffix() const {
426      return LabelSuffix;
427    }
428
429    const char *getDebugLabelSuffix() const {
430      return DebugLabelSuffix;
431    }
432    const char *getPrivateGlobalPrefix() const {
433      return PrivateGlobalPrefix;
434    }
435    bool hasLinkerPrivateGlobalPrefix() const {
436      return LinkerPrivateGlobalPrefix[0] != '\0';
437    }
438    const char *getLinkerPrivateGlobalPrefix() const {
439      if (hasLinkerPrivateGlobalPrefix())
440        return LinkerPrivateGlobalPrefix;
441      return getPrivateGlobalPrefix();
442    }
443    const char *getInlineAsmStart() const {
444      return InlineAsmStart;
445    }
446    const char *getInlineAsmEnd() const {
447      return InlineAsmEnd;
448    }
449    const char *getCode16Directive() const {
450      return Code16Directive;
451    }
452    const char *getCode32Directive() const {
453      return Code32Directive;
454    }
455    const char *getCode64Directive() const {
456      return Code64Directive;
457    }
458    unsigned getAssemblerDialect() const {
459      return AssemblerDialect;
460    }
461    bool doesAllowAtInName() const {
462      return AllowAtInName;
463    }
464    bool doesSupportDataRegionDirectives() const {
465      return UseDataRegionDirectives;
466    }
467    const char *getZeroDirective() const {
468      return ZeroDirective;
469    }
470    const char *getAsciiDirective() const {
471      return AsciiDirective;
472    }
473    const char *getAscizDirective() const {
474      return AscizDirective;
475    }
476    bool getAlignmentIsInBytes() const {
477      return AlignmentIsInBytes;
478    }
479    unsigned getTextAlignFillValue() const {
480      return TextAlignFillValue;
481    }
482    const char *getGlobalDirective() const {
483      return GlobalDirective;
484    }
485    bool hasSetDirective() const { return HasSetDirective; }
486    bool hasAggressiveSymbolFolding() const {
487      return HasAggressiveSymbolFolding;
488    }
489    bool getCOMMDirectiveAlignmentIsInBytes() const {
490      return COMMDirectiveAlignmentIsInBytes;
491    }
492    LCOMM::LCOMMType getLCOMMDirectiveAlignmentType() const {
493      return LCOMMDirectiveAlignmentType;
494    }
495    bool hasDotTypeDotSizeDirective() const {return HasDotTypeDotSizeDirective;}
496    bool hasSingleParameterDotFile() const { return HasSingleParameterDotFile; }
497    bool hasIdentDirective() const { return HasIdentDirective; }
498    bool hasNoDeadStrip() const { return HasNoDeadStrip; }
499    const char *getWeakRefDirective() const { return WeakRefDirective; }
500    bool hasWeakDefDirective() const { return HasWeakDefDirective; }
501    bool hasWeakDefCanBeHiddenDirective() const {
502      return HasWeakDefCanBeHiddenDirective;
503    }
504    bool hasLinkOnceDirective() const { return HasLinkOnceDirective; }
505
506    MCSymbolAttr getHiddenVisibilityAttr() const { return HiddenVisibilityAttr;}
507    MCSymbolAttr getHiddenDeclarationVisibilityAttr() const {
508      return HiddenDeclarationVisibilityAttr;
509    }
510    MCSymbolAttr getProtectedVisibilityAttr() const {
511      return ProtectedVisibilityAttr;
512    }
513    bool hasLEB128() const {
514      return HasLEB128;
515    }
516    bool doesSupportDebugInformation() const {
517      return SupportsDebugInformation;
518    }
519    bool doesSupportExceptionHandling() const {
520      return ExceptionsType != ExceptionHandling::None;
521    }
522    ExceptionHandling::ExceptionsType getExceptionHandlingType() const {
523      return ExceptionsType;
524    }
525    bool isExceptionHandlingDwarf() const {
526      return
527        (ExceptionsType == ExceptionHandling::DwarfCFI ||
528         ExceptionsType == ExceptionHandling::ARM ||
529         ExceptionsType == ExceptionHandling::Win64);
530    }
531    bool doesDwarfUseRelocationsAcrossSections() const {
532      return DwarfUsesRelocationsAcrossSections;
533    }
534    bool doDwarfFDESymbolsUseAbsDiff() const {
535      return DwarfFDESymbolsUseAbsDiff;
536    }
537    bool useDwarfRegNumForCFI() const {
538      return DwarfRegNumForCFI;
539    }
540    bool useParensForSymbolVariant() const {
541      return UseParensForSymbolVariant;
542    }
543
544    void addInitialFrameState(const MCCFIInstruction &Inst) {
545      InitialFrameState.push_back(Inst);
546    }
547
548    const std::vector<MCCFIInstruction> &getInitialFrameState() const {
549      return InitialFrameState;
550    }
551
552    /// Return true if assembly (inline or otherwise) should be parsed.
553    bool useIntegratedAssembler() const { return UseIntegratedAssembler; }
554
555    /// Set whether assembly (inline or otherwise) should be parsed.
556    virtual void setUseIntegratedAssembler(bool Value) {
557      UseIntegratedAssembler = Value;
558    }
559
560    bool compressDebugSections() const { return CompressDebugSections; }
561
562    void setCompressDebugSections(bool CompressDebugSections) {
563      this->CompressDebugSections = CompressDebugSections;
564    }
565  };
566}
567
568#endif
569