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/ADT/StringRef.h"
20 #include "llvm/MC/MCDirectives.h"
21 #include "llvm/MC/MCDwarf.h"
22 #include "llvm/MC/MCTargetOptions.h"
35 enum class EncodingType {
37 Alpha, /// Windows Alpha
38 Alpha64, /// Windows AXP64
39 ARM, /// Windows NT (Windows on ARM)
40 CE, /// Windows CE ARM, PowerPC, SH3, SH4
41 Itanium, /// Windows x64, Windows Itanium (IA-64)
42 X86, /// Windows x86, uses no CFI, just EH tables
46 } // end namespace WinEH
50 enum LCOMMType { NoAlignment, ByteAlignment, Log2Alignment };
52 } // end namespace LCOMM
54 /// This class is intended to be used as a base class for asm
55 /// properties and features specific to the target.
58 //===------------------------------------------------------------------===//
59 // Properties to be set by the target writer, used to configure asm printer.
62 /// Code pointer size in bytes. Default is 4.
63 unsigned CodePointerSize = 4;
65 /// Size of the stack slot reserved for callee-saved registers, in bytes.
66 /// Default is same as pointer size.
67 unsigned CalleeSaveStackSlotSize = 4;
69 /// True if target is little endian. Default is true.
70 bool IsLittleEndian = true;
72 /// True if target stack grow up. Default is false.
73 bool StackGrowsUp = false;
75 /// True if this target has the MachO .subsections_via_symbols directive.
77 bool HasSubsectionsViaSymbols = false;
79 /// True if this is a MachO target that supports the macho-specific .zerofill
80 /// directive for emitting BSS Symbols. Default is false.
81 bool HasMachoZeroFillDirective = false;
83 /// True if this is a MachO target that supports the macho-specific .tbss
84 /// directive for emitting thread local BSS Symbols. Default is false.
85 bool HasMachoTBSSDirective = false;
87 /// This is the maximum possible length of an instruction, which is needed to
88 /// compute the size of an inline asm. Defaults to 4.
89 unsigned MaxInstLength = 4;
91 /// Every possible instruction length is a multiple of this value. Factored
92 /// out in .debug_frame and .debug_line. Defaults to 1.
93 unsigned MinInstAlignment = 1;
95 /// The '$' token, when not referencing an identifier or constant, refers to
96 /// the current PC. Defaults to false.
97 bool DollarIsPC = false;
99 /// This string, if specified, is used to separate instructions from each
100 /// other when on the same line. Defaults to ';'
101 const char *SeparatorString;
103 /// This indicates the comment character used by the assembler. Defaults to
105 StringRef CommentString;
107 /// This is appended to emitted labels. Defaults to ":"
108 const char *LabelSuffix;
110 // Print the EH begin symbol with an assignment. Defaults to false.
111 bool UseAssignmentForEHBegin = false;
113 // Do we need to create a local symbol for .size?
114 bool NeedsLocalForSize = false;
116 /// This prefix is used for globals like constant pool entries that are
117 /// completely private to the .s file and should not have names in the .o
118 /// file. Defaults to "L"
119 StringRef PrivateGlobalPrefix;
121 /// This prefix is used for labels for basic blocks. Defaults to the same as
122 /// PrivateGlobalPrefix.
123 StringRef PrivateLabelPrefix;
125 /// This prefix is used for symbols that should be passed through the
126 /// assembler but be removed by the linker. This is 'l' on Darwin, currently
127 /// used for some ObjC metadata. The default of "" meast that for this system
128 /// a plain private symbol should be used. Defaults to "".
129 StringRef LinkerPrivateGlobalPrefix;
131 /// If these are nonempty, they contain a directive to emit before and after
132 /// an inline assembly statement. Defaults to "#APP\n", "#NO_APP\n"
133 const char *InlineAsmStart;
134 const char *InlineAsmEnd;
136 /// These are assembly directives that tells the assembler to interpret the
137 /// following instructions differently. Defaults to ".code16", ".code32",
139 const char *Code16Directive;
140 const char *Code32Directive;
141 const char *Code64Directive;
143 /// Which dialect of an assembler variant to use. Defaults to 0
144 unsigned AssemblerDialect = 0;
146 /// This is true if the assembler allows @ characters in symbol names.
147 /// Defaults to false.
148 bool AllowAtInName = false;
150 /// If this is true, symbol names with invalid characters will be printed in
152 bool SupportsQuotedNames = true;
154 /// This is true if data region markers should be printed as
155 /// ".data_region/.end_data_region" directives. If false, use "$d/$a" labels
157 bool UseDataRegionDirectives = false;
159 //===--- Data Emission Directives -------------------------------------===//
161 /// This should be set to the directive used to get some number of zero bytes
162 /// emitted to the current section. Common cases are "\t.zero\t" and
163 /// "\t.space\t". If this is set to null, the Data*bitsDirective's will be
164 /// used to emit zero bytes. Defaults to "\t.zero\t"
165 const char *ZeroDirective;
167 /// This directive allows emission of an ascii string with the standard C
168 /// escape characters embedded into it. If a target doesn't support this, it
169 /// can be set to null. Defaults to "\t.ascii\t"
170 const char *AsciiDirective;
172 /// If not null, this allows for special handling of zero terminated strings
173 /// on this target. This is commonly supported as ".asciz". If a target
174 /// doesn't support this, it can be set to null. Defaults to "\t.asciz\t"
175 const char *AscizDirective;
177 /// These directives are used to output some unit of integer data to the
178 /// current section. If a data directive is set to null, smaller data
179 /// directives will be used to emit the large sizes. Defaults to "\t.byte\t",
180 /// "\t.short\t", "\t.long\t", "\t.quad\t"
181 const char *Data8bitsDirective;
182 const char *Data16bitsDirective;
183 const char *Data32bitsDirective;
184 const char *Data64bitsDirective;
186 /// If non-null, a directive that is used to emit a word which should be
187 /// relocated as a 64-bit GP-relative offset, e.g. .gpdword on Mips. Defaults
189 const char *GPRel64Directive = nullptr;
191 /// If non-null, a directive that is used to emit a word which should be
192 /// relocated as a 32-bit GP-relative offset, e.g. .gpword on Mips or .gprel32
193 /// on Alpha. Defaults to nullptr.
194 const char *GPRel32Directive = nullptr;
196 /// If non-null, directives that are used to emit a word/dword which should
197 /// be relocated as a 32/64-bit DTP/TP-relative offset, e.g. .dtprelword/
198 /// .dtpreldword/.tprelword/.tpreldword on Mips.
199 const char *DTPRel32Directive = nullptr;
200 const char *DTPRel64Directive = nullptr;
201 const char *TPRel32Directive = nullptr;
202 const char *TPRel64Directive = nullptr;
204 /// This is true if this target uses "Sun Style" syntax for section switching
205 /// ("#alloc,#write" etc) instead of the normal ELF syntax (,"a,w") in
206 /// .section directives. Defaults to false.
207 bool SunStyleELFSectionSwitchSyntax = false;
209 /// This is true if this target uses ELF '.section' directive before the
210 /// '.bss' one. It's used for PPC/Linux which doesn't support the '.bss'
211 /// directive only. Defaults to false.
212 bool UsesELFSectionDirectiveForBSS = false;
214 bool NeedsDwarfSectionOffsetDirective = false;
216 //===--- Alignment Information ----------------------------------------===//
218 /// If this is true (the default) then the asmprinter emits ".align N"
219 /// directives, where N is the number of bytes to align to. Otherwise, it
220 /// emits ".align log2(N)", e.g. 3 to align to an 8 byte boundary. Defaults
222 bool AlignmentIsInBytes = true;
224 /// If non-zero, this is used to fill the executable space created as the
225 /// result of a alignment directive. Defaults to 0
226 unsigned TextAlignFillValue = 0;
228 //===--- Global Variable Emission Directives --------------------------===//
230 /// This is the directive used to declare a global entity. Defaults to
232 const char *GlobalDirective;
234 /// True if the expression
236 /// uses a relocation but it can be suppressed by writing
239 bool SetDirectiveSuppressesReloc = false;
241 /// False if the assembler requires that we use
253 /// Defaults to true.
254 bool HasAggressiveSymbolFolding = true;
256 /// True is .comm's and .lcomms optional alignment is to be specified in bytes
257 /// instead of log2(n). Defaults to true.
258 bool COMMDirectiveAlignmentIsInBytes = true;
260 /// Describes if the .lcomm directive for the target supports an alignment
261 /// argument and how it is interpreted. Defaults to NoAlignment.
262 LCOMM::LCOMMType LCOMMDirectiveAlignmentType = LCOMM::NoAlignment;
264 // True if the target allows .align directives on functions. This is true for
265 // most targets, so defaults to true.
266 bool HasFunctionAlignment = true;
268 /// True if the target has .type and .size directives, this is true for most
269 /// ELF targets. Defaults to true.
270 bool HasDotTypeDotSizeDirective = true;
272 /// True if the target has a single parameter .file directive, this is true
273 /// for ELF targets. Defaults to true.
274 bool HasSingleParameterDotFile = true;
276 /// True if the target has a .ident directive, this is true for ELF targets.
277 /// Defaults to false.
278 bool HasIdentDirective = false;
280 /// True if this target supports the MachO .no_dead_strip directive. Defaults
282 bool HasNoDeadStrip = false;
284 /// True if this target supports the MachO .alt_entry directive. Defaults to
286 bool HasAltEntry = false;
288 /// Used to declare a global as being a weak symbol. Defaults to ".weak".
289 const char *WeakDirective;
291 /// This directive, if non-null, is used to declare a global as being a weak
292 /// undefined symbol. Defaults to nullptr.
293 const char *WeakRefDirective = nullptr;
295 /// True if we have a directive to declare a global as being a weak defined
296 /// symbol. Defaults to false.
297 bool HasWeakDefDirective = false;
299 /// True if we have a directive to declare a global as being a weak defined
300 /// symbol that can be hidden (unexported). Defaults to false.
301 bool HasWeakDefCanBeHiddenDirective = false;
303 /// True if we have a .linkonce directive. This is used on cygwin/mingw.
304 /// Defaults to false.
305 bool HasLinkOnceDirective = false;
307 /// This attribute, if not MCSA_Invalid, is used to declare a symbol as having
308 /// hidden visibility. Defaults to MCSA_Hidden.
309 MCSymbolAttr HiddenVisibilityAttr = MCSA_Hidden;
311 /// This attribute, if not MCSA_Invalid, is used to declare an undefined
312 /// symbol as having hidden visibility. Defaults to MCSA_Hidden.
313 MCSymbolAttr HiddenDeclarationVisibilityAttr = MCSA_Hidden;
315 /// This attribute, if not MCSA_Invalid, is used to declare a symbol as having
316 /// protected visibility. Defaults to MCSA_Protected
317 MCSymbolAttr ProtectedVisibilityAttr = MCSA_Protected;
319 //===--- Dwarf Emission Directives -----------------------------------===//
321 /// True if target supports emission of debugging information. Defaults to
323 bool SupportsDebugInformation = false;
325 /// Exception handling format for the target. Defaults to None.
326 ExceptionHandling ExceptionsType = ExceptionHandling::None;
328 /// Windows exception handling data (.pdata) encoding. Defaults to Invalid.
329 WinEH::EncodingType WinEHEncodingType = WinEH::EncodingType::Invalid;
331 /// True if Dwarf2 output generally uses relocations for references to other
332 /// .debug_* sections.
333 bool DwarfUsesRelocationsAcrossSections = true;
335 /// True if DWARF FDE symbol reference relocations should be replaced by an
336 /// absolute difference.
337 bool DwarfFDESymbolsUseAbsDiff = false;
339 /// True if dwarf register numbers are printed instead of symbolic register
340 /// names in .cfi_* directives. Defaults to false.
341 bool DwarfRegNumForCFI = false;
343 /// True if target uses parens to indicate the symbol variant instead of @.
344 /// For example, foo(plt) instead of foo@plt. Defaults to false.
345 bool UseParensForSymbolVariant = false;
347 /// True if the target supports flags in ".loc" directive, false if only
348 /// location is allowed.
349 bool SupportsExtendedDwarfLocDirective = true;
351 //===--- Prologue State ----------------------------------------------===//
353 std::vector<MCCFIInstruction> InitialFrameState;
355 //===--- Integrated Assembler Information ----------------------------===//
357 /// Should we use the integrated assembler?
358 /// The integrated assembler should be enabled by default (by the
359 /// constructors) when failing to parse a valid piece of assembly (inline
360 /// or otherwise) is considered a bug. It may then be overridden after
361 /// construction (see LLVMTargetMachine::initAsmInfo()).
362 bool UseIntegratedAssembler;
364 /// Preserve Comments in assembly
365 bool PreserveAsmComments;
367 /// Compress DWARF debug sections. Defaults to no compression.
368 DebugCompressionType CompressDebugSections = DebugCompressionType::None;
370 /// True if the integrated assembler should interpret 'a >> b' constant
371 /// expressions as logical rather than arithmetic.
372 bool UseLogicalShr = true;
374 // If true, emit GOTPCRELX/REX_GOTPCRELX instead of GOTPCREL, on
376 bool RelaxELFRelocations = true;
378 // If true, then the lexer and expression parser will support %neg(),
379 // %hi(), and similar unary operators.
380 bool HasMipsExpressions = false;
383 explicit MCAsmInfo();
384 virtual ~MCAsmInfo();
386 /// Get the code pointer size in bytes.
387 unsigned getCodePointerSize() const { return CodePointerSize; }
389 /// Get the callee-saved register stack slot
391 unsigned getCalleeSaveStackSlotSize() const {
392 return CalleeSaveStackSlotSize;
395 /// True if the target is little endian.
396 bool isLittleEndian() const { return IsLittleEndian; }
398 /// True if target stack grow up.
399 bool isStackGrowthDirectionUp() const { return StackGrowsUp; }
401 bool hasSubsectionsViaSymbols() const { return HasSubsectionsViaSymbols; }
403 // Data directive accessors.
405 const char *getData8bitsDirective() const { return Data8bitsDirective; }
406 const char *getData16bitsDirective() const { return Data16bitsDirective; }
407 const char *getData32bitsDirective() const { return Data32bitsDirective; }
408 const char *getData64bitsDirective() const { return Data64bitsDirective; }
409 const char *getGPRel64Directive() const { return GPRel64Directive; }
410 const char *getGPRel32Directive() const { return GPRel32Directive; }
411 const char *getDTPRel64Directive() const { return DTPRel64Directive; }
412 const char *getDTPRel32Directive() const { return DTPRel32Directive; }
413 const char *getTPRel64Directive() const { return TPRel64Directive; }
414 const char *getTPRel32Directive() const { return TPRel32Directive; }
416 /// Targets can implement this method to specify a section to switch to if the
417 /// translation unit doesn't have any trampolines that require an executable
419 virtual MCSection *getNonexecutableStackSection(MCContext &Ctx) const {
423 /// True if the section is atomized using the symbols in it.
424 /// This is false if the section is not atomized at all (most ELF sections) or
425 /// if it is atomized based on its contents (MachO' __TEXT,__cstring for
427 virtual bool isSectionAtomizableBySymbols(const MCSection &Section) const;
429 virtual const MCExpr *getExprForPersonalitySymbol(const MCSymbol *Sym,
431 MCStreamer &Streamer) const;
433 virtual const MCExpr *getExprForFDESymbol(const MCSymbol *Sym,
435 MCStreamer &Streamer) const;
437 /// Return true if the identifier \p Name does not need quotes to be
438 /// syntactically correct.
439 virtual bool isValidUnquotedName(StringRef Name) const;
441 /// Return true if the .section directive should be omitted when
442 /// emitting \p SectionName. For example:
444 /// shouldOmitSectionDirective(".text")
446 /// returns false => .section .text,#alloc,#execinstr
447 /// returns true => .text
448 virtual bool shouldOmitSectionDirective(StringRef SectionName) const;
450 bool usesSunStyleELFSectionSwitchSyntax() const {
451 return SunStyleELFSectionSwitchSyntax;
454 bool usesELFSectionDirectiveForBSS() const {
455 return UsesELFSectionDirectiveForBSS;
458 bool needsDwarfSectionOffsetDirective() const {
459 return NeedsDwarfSectionOffsetDirective;
464 bool hasMachoZeroFillDirective() const { return HasMachoZeroFillDirective; }
465 bool hasMachoTBSSDirective() const { return HasMachoTBSSDirective; }
466 unsigned getMaxInstLength() const { return MaxInstLength; }
467 unsigned getMinInstAlignment() const { return MinInstAlignment; }
468 bool getDollarIsPC() const { return DollarIsPC; }
469 const char *getSeparatorString() const { return SeparatorString; }
471 /// This indicates the column (zero-based) at which asm comments should be
473 unsigned getCommentColumn() const { return 40; }
475 StringRef getCommentString() const { return CommentString; }
476 const char *getLabelSuffix() const { return LabelSuffix; }
478 bool useAssignmentForEHBegin() const { return UseAssignmentForEHBegin; }
479 bool needsLocalForSize() const { return NeedsLocalForSize; }
480 StringRef getPrivateGlobalPrefix() const { return PrivateGlobalPrefix; }
481 StringRef getPrivateLabelPrefix() const { return PrivateLabelPrefix; }
483 bool hasLinkerPrivateGlobalPrefix() const {
484 return LinkerPrivateGlobalPrefix[0] != '\0';
487 StringRef getLinkerPrivateGlobalPrefix() const {
488 if (hasLinkerPrivateGlobalPrefix())
489 return LinkerPrivateGlobalPrefix;
490 return getPrivateGlobalPrefix();
493 const char *getInlineAsmStart() const { return InlineAsmStart; }
494 const char *getInlineAsmEnd() const { return InlineAsmEnd; }
495 const char *getCode16Directive() const { return Code16Directive; }
496 const char *getCode32Directive() const { return Code32Directive; }
497 const char *getCode64Directive() const { return Code64Directive; }
498 unsigned getAssemblerDialect() const { return AssemblerDialect; }
499 bool doesAllowAtInName() const { return AllowAtInName; }
500 bool supportsNameQuoting() const { return SupportsQuotedNames; }
502 bool doesSupportDataRegionDirectives() const {
503 return UseDataRegionDirectives;
506 const char *getZeroDirective() const { return ZeroDirective; }
507 const char *getAsciiDirective() const { return AsciiDirective; }
508 const char *getAscizDirective() const { return AscizDirective; }
509 bool getAlignmentIsInBytes() const { return AlignmentIsInBytes; }
510 unsigned getTextAlignFillValue() const { return TextAlignFillValue; }
511 const char *getGlobalDirective() const { return GlobalDirective; }
513 bool doesSetDirectiveSuppressReloc() const {
514 return SetDirectiveSuppressesReloc;
517 bool hasAggressiveSymbolFolding() const { return HasAggressiveSymbolFolding; }
519 bool getCOMMDirectiveAlignmentIsInBytes() const {
520 return COMMDirectiveAlignmentIsInBytes;
523 LCOMM::LCOMMType getLCOMMDirectiveAlignmentType() const {
524 return LCOMMDirectiveAlignmentType;
527 bool hasFunctionAlignment() const { return HasFunctionAlignment; }
528 bool hasDotTypeDotSizeDirective() const { return HasDotTypeDotSizeDirective; }
529 bool hasSingleParameterDotFile() const { return HasSingleParameterDotFile; }
530 bool hasIdentDirective() const { return HasIdentDirective; }
531 bool hasNoDeadStrip() const { return HasNoDeadStrip; }
532 bool hasAltEntry() const { return HasAltEntry; }
533 const char *getWeakDirective() const { return WeakDirective; }
534 const char *getWeakRefDirective() const { return WeakRefDirective; }
535 bool hasWeakDefDirective() const { return HasWeakDefDirective; }
537 bool hasWeakDefCanBeHiddenDirective() const {
538 return HasWeakDefCanBeHiddenDirective;
541 bool hasLinkOnceDirective() const { return HasLinkOnceDirective; }
543 MCSymbolAttr getHiddenVisibilityAttr() const { return HiddenVisibilityAttr; }
545 MCSymbolAttr getHiddenDeclarationVisibilityAttr() const {
546 return HiddenDeclarationVisibilityAttr;
549 MCSymbolAttr getProtectedVisibilityAttr() const {
550 return ProtectedVisibilityAttr;
553 bool doesSupportDebugInformation() const { return SupportsDebugInformation; }
555 bool doesSupportExceptionHandling() const {
556 return ExceptionsType != ExceptionHandling::None;
559 ExceptionHandling getExceptionHandlingType() const { return ExceptionsType; }
560 WinEH::EncodingType getWinEHEncodingType() const { return WinEHEncodingType; }
562 void setExceptionsType(ExceptionHandling EH) {
566 /// Returns true if the exception handling method for the platform uses call
567 /// frame information to unwind.
568 bool usesCFIForEH() const {
569 return (ExceptionsType == ExceptionHandling::DwarfCFI ||
570 ExceptionsType == ExceptionHandling::ARM || usesWindowsCFI());
573 bool usesWindowsCFI() const {
574 return ExceptionsType == ExceptionHandling::WinEH &&
575 (WinEHEncodingType != WinEH::EncodingType::Invalid &&
576 WinEHEncodingType != WinEH::EncodingType::X86);
579 bool doesDwarfUseRelocationsAcrossSections() const {
580 return DwarfUsesRelocationsAcrossSections;
583 bool doDwarfFDESymbolsUseAbsDiff() const { return DwarfFDESymbolsUseAbsDiff; }
584 bool useDwarfRegNumForCFI() const { return DwarfRegNumForCFI; }
585 bool useParensForSymbolVariant() const { return UseParensForSymbolVariant; }
586 bool supportsExtendedDwarfLocDirective() const {
587 return SupportsExtendedDwarfLocDirective;
590 void addInitialFrameState(const MCCFIInstruction &Inst) {
591 InitialFrameState.push_back(Inst);
594 const std::vector<MCCFIInstruction> &getInitialFrameState() const {
595 return InitialFrameState;
598 /// Return true if assembly (inline or otherwise) should be parsed.
599 bool useIntegratedAssembler() const { return UseIntegratedAssembler; }
601 /// Set whether assembly (inline or otherwise) should be parsed.
602 virtual void setUseIntegratedAssembler(bool Value) {
603 UseIntegratedAssembler = Value;
606 /// Return true if assembly (inline or otherwise) should be parsed.
607 bool preserveAsmComments() const { return PreserveAsmComments; }
609 /// Set whether assembly (inline or otherwise) should be parsed.
610 virtual void setPreserveAsmComments(bool Value) {
611 PreserveAsmComments = Value;
614 DebugCompressionType compressDebugSections() const {
615 return CompressDebugSections;
618 void setCompressDebugSections(DebugCompressionType CompressDebugSections) {
619 this->CompressDebugSections = CompressDebugSections;
622 bool shouldUseLogicalShr() const { return UseLogicalShr; }
624 bool canRelaxRelocations() const { return RelaxELFRelocations; }
625 void setRelaxELFRelocations(bool V) { RelaxELFRelocations = V; }
626 bool hasMipsExpressions() const { return HasMipsExpressions; }
629 } // end namespace llvm
631 #endif // LLVM_MC_MCASMINFO_H