1 //===-- llvm/MC/MCAsmInfo.h - Asm info --------------------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
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.
14 //===----------------------------------------------------------------------===//
16 #ifndef LLVM_MC_MCASMINFO_H
17 #define LLVM_MC_MCASMINFO_H
19 #include "llvm/MC/MCDirectives.h"
20 #include "llvm/MC/MCDwarf.h"
32 enum class EncodingType {
34 Alpha, /// Windows Alpha
35 Alpha64, /// Windows AXP64
36 ARM, /// Windows NT (Windows on ARM)
37 CE, /// Windows CE ARM, PowerPC, SH3, SH4
38 Itanium, /// Windows x64, Windows Itanium (IA-64)
39 X86, /// Windows x86, uses no CFI, just EH tables
44 enum class ExceptionHandling {
45 None, /// No exception support
46 DwarfCFI, /// DWARF-like instruction based exceptions
47 SjLj, /// setjmp/longjmp based exceptions
49 WinEH, /// Windows Exception Handling
53 enum LCOMMType { NoAlignment, ByteAlignment, Log2Alignment };
56 /// This class is intended to be used as a base class for asm
57 /// properties and features specific to the target.
60 //===------------------------------------------------------------------===//
61 // Properties to be set by the target writer, used to configure asm printer.
64 /// Pointer size in bytes. Default is 4.
67 /// Size of the stack slot reserved for callee-saved registers, in bytes.
68 /// Default is same as pointer size.
69 unsigned CalleeSaveStackSlotSize;
71 /// True if target is little endian. Default is true.
74 /// True if target stack grow up. Default is false.
77 /// True if this target has the MachO .subsections_via_symbols directive.
79 bool HasSubsectionsViaSymbols;
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;
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;
89 /// True if the compiler should emit a ".reference .constructors_used" or
90 /// ".reference .destructors_used" directive after the static ctor/dtor
91 /// list. This directive is only emitted in Static relocation model. Default
93 bool HasStaticCtorDtorReferenceInStaticMode;
95 /// This is the maximum possible length of an instruction, which is needed to
96 /// compute the size of an inline asm. Defaults to 4.
97 unsigned MaxInstLength;
99 /// Every possible instruction length is a multiple of this value. Factored
100 /// out in .debug_frame and .debug_line. Defaults to 1.
101 unsigned MinInstAlignment;
103 /// The '$' token, when not referencing an identifier or constant, refers to
104 /// the current PC. Defaults to false.
107 /// This string, if specified, is used to separate instructions from each
108 /// other when on the same line. Defaults to ';'
109 const char *SeparatorString;
111 /// This indicates the comment character used by the assembler. Defaults to
113 const char *CommentString;
115 /// This is appended to emitted labels. Defaults to ":"
116 const char *LabelSuffix;
118 // Print the EH begin symbol with an assignment. Defaults to false.
119 bool UseAssignmentForEHBegin;
121 // Do we need to create a local symbol for .size?
122 bool NeedsLocalForSize;
124 /// This prefix is used for globals like constant pool entries that are
125 /// completely private to the .s file and should not have names in the .o
126 /// file. Defaults to "L"
127 const char *PrivateGlobalPrefix;
129 /// This prefix is used for labels for basic blocks. Defaults to the same as
130 /// PrivateGlobalPrefix.
131 const char *PrivateLabelPrefix;
133 /// This prefix is used for symbols that should be passed through the
134 /// assembler but be removed by the linker. This is 'l' on Darwin, currently
135 /// used for some ObjC metadata. The default of "" meast that for this system
136 /// a plain private symbol should be used. Defaults to "".
137 const char *LinkerPrivateGlobalPrefix;
139 /// If these are nonempty, they contain a directive to emit before and after
140 /// an inline assembly statement. Defaults to "#APP\n", "#NO_APP\n"
141 const char *InlineAsmStart;
142 const char *InlineAsmEnd;
144 /// These are assembly directives that tells the assembler to interpret the
145 /// following instructions differently. Defaults to ".code16", ".code32",
147 const char *Code16Directive;
148 const char *Code32Directive;
149 const char *Code64Directive;
151 /// Which dialect of an assembler variant to use. Defaults to 0
152 unsigned AssemblerDialect;
154 /// This is true if the assembler allows @ characters in symbol names.
155 /// Defaults to false.
158 /// This is true if data region markers should be printed as
159 /// ".data_region/.end_data_region" directives. If false, use "$d/$a" labels
161 bool UseDataRegionDirectives;
163 //===--- Data Emission Directives -------------------------------------===//
165 /// This should be set to the directive used to get some number of zero bytes
166 /// emitted to the current section. Common cases are "\t.zero\t" and
167 /// "\t.space\t". If this is set to null, the Data*bitsDirective's will be
168 /// used to emit zero bytes. Defaults to "\t.zero\t"
169 const char *ZeroDirective;
171 /// This directive allows emission of an ascii string with the standard C
172 /// escape characters embedded into it. Defaults to "\t.ascii\t"
173 const char *AsciiDirective;
175 /// If not null, this allows for special handling of zero terminated strings
176 /// on this target. This is commonly supported as ".asciz". If a target
177 /// doesn't support this, it can be set to null. Defaults to "\t.asciz\t"
178 const char *AscizDirective;
180 /// These directives are used to output some unit of integer data to the
181 /// current section. If a data directive is set to null, smaller data
182 /// directives will be used to emit the large sizes. Defaults to "\t.byte\t",
183 /// "\t.short\t", "\t.long\t", "\t.quad\t"
184 const char *Data8bitsDirective;
185 const char *Data16bitsDirective;
186 const char *Data32bitsDirective;
187 const char *Data64bitsDirective;
189 /// If non-null, a directive that is used to emit a word which should be
190 /// relocated as a 64-bit GP-relative offset, e.g. .gpdword on Mips. Defaults
192 const char *GPRel64Directive;
194 /// If non-null, a directive that is used to emit a word which should be
195 /// relocated as a 32-bit GP-relative offset, e.g. .gpword on Mips or .gprel32
196 /// on Alpha. Defaults to NULL.
197 const char *GPRel32Directive;
199 /// This is true if this target uses "Sun Style" syntax for section switching
200 /// ("#alloc,#write" etc) instead of the normal ELF syntax (,"a,w") in
201 /// .section directives. Defaults to false.
202 bool SunStyleELFSectionSwitchSyntax;
204 /// This is true if this target uses ELF '.section' directive before the
205 /// '.bss' one. It's used for PPC/Linux which doesn't support the '.bss'
206 /// directive only. Defaults to false.
207 bool UsesELFSectionDirectiveForBSS;
209 bool NeedsDwarfSectionOffsetDirective;
211 //===--- Alignment Information ----------------------------------------===//
213 /// If this is true (the default) then the asmprinter emits ".align N"
214 /// directives, where N is the number of bytes to align to. Otherwise, it
215 /// emits ".align log2(N)", e.g. 3 to align to an 8 byte boundary. Defaults
217 bool AlignmentIsInBytes;
219 /// If non-zero, this is used to fill the executable space created as the
220 /// result of a alignment directive. Defaults to 0
221 unsigned TextAlignFillValue;
223 //===--- Global Variable Emission Directives --------------------------===//
225 /// This is the directive used to declare a global entity. Defaults to
227 const char *GlobalDirective;
229 /// True if the expression
231 /// uses a relocation but it can be suppressed by writing
234 bool SetDirectiveSuppressesReloc;
236 /// False if the assembler requires that we use
248 /// Defaults to true.
249 bool HasAggressiveSymbolFolding;
251 /// True is .comm's and .lcomms optional alignment is to be specified in bytes
252 /// instead of log2(n). Defaults to true.
253 bool COMMDirectiveAlignmentIsInBytes;
255 /// Describes if the .lcomm directive for the target supports an alignment
256 /// argument and how it is interpreted. Defaults to NoAlignment.
257 LCOMM::LCOMMType LCOMMDirectiveAlignmentType;
259 // True if the target allows .align directives on functions. This is true for
260 // most targets, so defaults to true.
261 bool HasFunctionAlignment;
263 /// True if the target has .type and .size directives, this is true for most
264 /// ELF targets. Defaults to true.
265 bool HasDotTypeDotSizeDirective;
267 /// True if the target has a single parameter .file directive, this is true
268 /// for ELF targets. Defaults to true.
269 bool HasSingleParameterDotFile;
271 /// True if the target has a .ident directive, this is true for ELF targets.
272 /// Defaults to false.
273 bool HasIdentDirective;
275 /// True if this target supports the MachO .no_dead_strip directive. Defaults
279 /// Used to declare a global as being a weak symbol. Defaults to ".weak".
280 const char *WeakDirective;
282 /// This directive, if non-null, is used to declare a global as being a weak
283 /// undefined symbol. Defaults to NULL.
284 const char *WeakRefDirective;
286 /// True if we have a directive to declare a global as being a weak defined
287 /// symbol. Defaults to false.
288 bool HasWeakDefDirective;
290 /// True if we have a directive to declare a global as being a weak defined
291 /// symbol that can be hidden (unexported). Defaults to false.
292 bool HasWeakDefCanBeHiddenDirective;
294 /// True if we have a .linkonce directive. This is used on cygwin/mingw.
295 /// Defaults to false.
296 bool HasLinkOnceDirective;
298 /// This attribute, if not MCSA_Invalid, is used to declare a symbol as having
299 /// hidden visibility. Defaults to MCSA_Hidden.
300 MCSymbolAttr HiddenVisibilityAttr;
302 /// This attribute, if not MCSA_Invalid, is used to declare an undefined
303 /// symbol as having hidden visibility. Defaults to MCSA_Hidden.
304 MCSymbolAttr HiddenDeclarationVisibilityAttr;
306 /// This attribute, if not MCSA_Invalid, is used to declare a symbol as having
307 /// protected visibility. Defaults to MCSA_Protected
308 MCSymbolAttr ProtectedVisibilityAttr;
310 //===--- Dwarf Emission Directives -----------------------------------===//
312 /// True if target supports emission of debugging information. Defaults to
314 bool SupportsDebugInformation;
316 /// Exception handling format for the target. Defaults to None.
317 ExceptionHandling ExceptionsType;
319 /// Windows exception handling data (.pdata) encoding. Defaults to Invalid.
320 WinEH::EncodingType WinEHEncodingType;
322 /// True if Dwarf2 output generally uses relocations for references to other
323 /// .debug_* sections.
324 bool DwarfUsesRelocationsAcrossSections;
326 /// True if DWARF FDE symbol reference relocations should be replaced by an
327 /// absolute difference.
328 bool DwarfFDESymbolsUseAbsDiff;
330 /// True if dwarf register numbers are printed instead of symbolic register
331 /// names in .cfi_* directives. Defaults to false.
332 bool DwarfRegNumForCFI;
334 /// True if target uses parens to indicate the symbol variant instead of @.
335 /// For example, foo(plt) instead of foo@plt. Defaults to false.
336 bool UseParensForSymbolVariant;
338 //===--- Prologue State ----------------------------------------------===//
340 std::vector<MCCFIInstruction> InitialFrameState;
342 //===--- Integrated Assembler Information ----------------------------===//
344 /// Should we use the integrated assembler?
345 /// The integrated assembler should be enabled by default (by the
346 /// constructors) when failing to parse a valid piece of assembly (inline
347 /// or otherwise) is considered a bug. It may then be overridden after
348 /// construction (see LLVMTargetMachine::initAsmInfo()).
349 bool UseIntegratedAssembler;
351 /// Compress DWARF debug sections. Defaults to false.
352 bool CompressDebugSections;
354 /// True if the integrated assembler should interpret 'a >> b' constant
355 /// expressions as logical rather than arithmetic.
359 explicit MCAsmInfo();
360 virtual ~MCAsmInfo();
362 /// Get the pointer size in bytes.
363 unsigned getPointerSize() const { return PointerSize; }
365 /// Get the callee-saved register stack slot
367 unsigned getCalleeSaveStackSlotSize() const {
368 return CalleeSaveStackSlotSize;
371 /// True if the target is little endian.
372 bool isLittleEndian() const { return IsLittleEndian; }
374 /// True if target stack grow up.
375 bool isStackGrowthDirectionUp() const { return StackGrowsUp; }
377 bool hasSubsectionsViaSymbols() const { return HasSubsectionsViaSymbols; }
379 // Data directive accessors.
381 const char *getData8bitsDirective() const { return Data8bitsDirective; }
382 const char *getData16bitsDirective() const { return Data16bitsDirective; }
383 const char *getData32bitsDirective() const { return Data32bitsDirective; }
384 const char *getData64bitsDirective() const { return Data64bitsDirective; }
385 const char *getGPRel64Directive() const { return GPRel64Directive; }
386 const char *getGPRel32Directive() const { return GPRel32Directive; }
388 /// Targets can implement this method to specify a section to switch to if the
389 /// translation unit doesn't have any trampolines that require an executable
391 virtual MCSection *getNonexecutableStackSection(MCContext &Ctx) const {
395 /// \brief True if the section is atomized using the symbols in it.
396 /// This is false if the section is not atomized at all (most ELF sections) or
397 /// if it is atomized based on its contents (MachO' __TEXT,__cstring for
399 virtual bool isSectionAtomizableBySymbols(const MCSection &Section) const;
401 virtual const MCExpr *getExprForPersonalitySymbol(const MCSymbol *Sym,
403 MCStreamer &Streamer) const;
405 virtual const MCExpr *getExprForFDESymbol(const MCSymbol *Sym,
407 MCStreamer &Streamer) const;
409 bool usesSunStyleELFSectionSwitchSyntax() const {
410 return SunStyleELFSectionSwitchSyntax;
413 bool usesELFSectionDirectiveForBSS() const {
414 return UsesELFSectionDirectiveForBSS;
417 bool needsDwarfSectionOffsetDirective() const {
418 return NeedsDwarfSectionOffsetDirective;
423 bool hasMachoZeroFillDirective() const { return HasMachoZeroFillDirective; }
424 bool hasMachoTBSSDirective() const { return HasMachoTBSSDirective; }
425 bool hasStaticCtorDtorReferenceInStaticMode() const {
426 return HasStaticCtorDtorReferenceInStaticMode;
428 unsigned getMaxInstLength() const { return MaxInstLength; }
429 unsigned getMinInstAlignment() const { return MinInstAlignment; }
430 bool getDollarIsPC() const { return DollarIsPC; }
431 const char *getSeparatorString() const { return SeparatorString; }
433 /// This indicates the column (zero-based) at which asm comments should be
435 unsigned getCommentColumn() const { return 40; }
437 const char *getCommentString() const { return CommentString; }
438 const char *getLabelSuffix() const { return LabelSuffix; }
440 bool useAssignmentForEHBegin() const { return UseAssignmentForEHBegin; }
441 bool needsLocalForSize() const { return NeedsLocalForSize; }
442 const char *getPrivateGlobalPrefix() const { return PrivateGlobalPrefix; }
443 const char *getPrivateLabelPrefix() const { return PrivateLabelPrefix; }
444 bool hasLinkerPrivateGlobalPrefix() const {
445 return LinkerPrivateGlobalPrefix[0] != '\0';
447 const char *getLinkerPrivateGlobalPrefix() const {
448 if (hasLinkerPrivateGlobalPrefix())
449 return LinkerPrivateGlobalPrefix;
450 return getPrivateGlobalPrefix();
452 const char *getInlineAsmStart() const { return InlineAsmStart; }
453 const char *getInlineAsmEnd() const { return InlineAsmEnd; }
454 const char *getCode16Directive() const { return Code16Directive; }
455 const char *getCode32Directive() const { return Code32Directive; }
456 const char *getCode64Directive() const { return Code64Directive; }
457 unsigned getAssemblerDialect() const { return AssemblerDialect; }
458 bool doesAllowAtInName() const { return AllowAtInName; }
459 bool doesSupportDataRegionDirectives() const {
460 return UseDataRegionDirectives;
462 const char *getZeroDirective() const { return ZeroDirective; }
463 const char *getAsciiDirective() const { return AsciiDirective; }
464 const char *getAscizDirective() const { return AscizDirective; }
465 bool getAlignmentIsInBytes() const { return AlignmentIsInBytes; }
466 unsigned getTextAlignFillValue() const { return TextAlignFillValue; }
467 const char *getGlobalDirective() const { return GlobalDirective; }
468 bool doesSetDirectiveSuppressesReloc() const {
469 return SetDirectiveSuppressesReloc;
471 bool hasAggressiveSymbolFolding() const { return HasAggressiveSymbolFolding; }
472 bool getCOMMDirectiveAlignmentIsInBytes() const {
473 return COMMDirectiveAlignmentIsInBytes;
475 LCOMM::LCOMMType getLCOMMDirectiveAlignmentType() const {
476 return LCOMMDirectiveAlignmentType;
478 bool hasFunctionAlignment() const { return HasFunctionAlignment; }
479 bool hasDotTypeDotSizeDirective() const { return HasDotTypeDotSizeDirective; }
480 bool hasSingleParameterDotFile() const { return HasSingleParameterDotFile; }
481 bool hasIdentDirective() const { return HasIdentDirective; }
482 bool hasNoDeadStrip() const { return HasNoDeadStrip; }
483 const char *getWeakDirective() const { return WeakDirective; }
484 const char *getWeakRefDirective() const { return WeakRefDirective; }
485 bool hasWeakDefDirective() const { return HasWeakDefDirective; }
486 bool hasWeakDefCanBeHiddenDirective() const {
487 return HasWeakDefCanBeHiddenDirective;
489 bool hasLinkOnceDirective() const { return HasLinkOnceDirective; }
491 MCSymbolAttr getHiddenVisibilityAttr() const { return HiddenVisibilityAttr; }
492 MCSymbolAttr getHiddenDeclarationVisibilityAttr() const {
493 return HiddenDeclarationVisibilityAttr;
495 MCSymbolAttr getProtectedVisibilityAttr() const {
496 return ProtectedVisibilityAttr;
498 bool doesSupportDebugInformation() const { return SupportsDebugInformation; }
499 bool doesSupportExceptionHandling() const {
500 return ExceptionsType != ExceptionHandling::None;
502 ExceptionHandling getExceptionHandlingType() const { return ExceptionsType; }
503 WinEH::EncodingType getWinEHEncodingType() const { return WinEHEncodingType; }
505 /// Returns true if the exception handling method for the platform uses call
506 /// frame information to unwind.
507 bool usesCFIForEH() const {
508 return (ExceptionsType == ExceptionHandling::DwarfCFI ||
509 ExceptionsType == ExceptionHandling::ARM || usesWindowsCFI());
512 bool usesWindowsCFI() const {
513 return ExceptionsType == ExceptionHandling::WinEH &&
514 (WinEHEncodingType != WinEH::EncodingType::Invalid &&
515 WinEHEncodingType != WinEH::EncodingType::X86);
518 bool doesDwarfUseRelocationsAcrossSections() const {
519 return DwarfUsesRelocationsAcrossSections;
521 bool doDwarfFDESymbolsUseAbsDiff() const { return DwarfFDESymbolsUseAbsDiff; }
522 bool useDwarfRegNumForCFI() const { return DwarfRegNumForCFI; }
523 bool useParensForSymbolVariant() const { return UseParensForSymbolVariant; }
525 void addInitialFrameState(const MCCFIInstruction &Inst) {
526 InitialFrameState.push_back(Inst);
529 const std::vector<MCCFIInstruction> &getInitialFrameState() const {
530 return InitialFrameState;
533 /// Return true if assembly (inline or otherwise) should be parsed.
534 bool useIntegratedAssembler() const { return UseIntegratedAssembler; }
536 /// Set whether assembly (inline or otherwise) should be parsed.
537 virtual void setUseIntegratedAssembler(bool Value) {
538 UseIntegratedAssembler = Value;
541 bool compressDebugSections() const { return CompressDebugSections; }
543 void setCompressDebugSections(bool CompressDebugSections) {
544 this->CompressDebugSections = CompressDebugSections;
547 bool shouldUseLogicalShr() const { return UseLogicalShr; }