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 /// True if this is a non-GNU COFF target. The COFF port of the GNU linker
88 /// doesn't handle associative comdats in the way that we would like to use
90 bool HasCOFFAssociativeComdats = false;
92 /// True if this is a non-GNU COFF target. For GNU targets, we don't generate
93 /// constants into comdat sections.
94 bool HasCOFFComdatConstants = false;
96 /// This is the maximum possible length of an instruction, which is needed to
97 /// compute the size of an inline asm. Defaults to 4.
98 unsigned MaxInstLength = 4;
100 /// Every possible instruction length is a multiple of this value. Factored
101 /// out in .debug_frame and .debug_line. Defaults to 1.
102 unsigned MinInstAlignment = 1;
104 /// The '$' token, when not referencing an identifier or constant, refers to
105 /// the current PC. Defaults to false.
106 bool DollarIsPC = false;
108 /// This string, if specified, is used to separate instructions from each
109 /// other when on the same line. Defaults to ';'
110 const char *SeparatorString;
112 /// This indicates the comment character used by the assembler. Defaults to
114 StringRef CommentString;
116 /// This is appended to emitted labels. Defaults to ":"
117 const char *LabelSuffix;
119 // Print the EH begin symbol with an assignment. Defaults to false.
120 bool UseAssignmentForEHBegin = false;
122 // Do we need to create a local symbol for .size?
123 bool NeedsLocalForSize = false;
125 /// This prefix is used for globals like constant pool entries that are
126 /// completely private to the .s file and should not have names in the .o
127 /// file. Defaults to "L"
128 StringRef PrivateGlobalPrefix;
130 /// This prefix is used for labels for basic blocks. Defaults to the same as
131 /// PrivateGlobalPrefix.
132 StringRef PrivateLabelPrefix;
134 /// This prefix is used for symbols that should be passed through the
135 /// assembler but be removed by the linker. This is 'l' on Darwin, currently
136 /// used for some ObjC metadata. The default of "" meast that for this system
137 /// a plain private symbol should be used. Defaults to "".
138 StringRef LinkerPrivateGlobalPrefix;
140 /// If these are nonempty, they contain a directive to emit before and after
141 /// an inline assembly statement. Defaults to "#APP\n", "#NO_APP\n"
142 const char *InlineAsmStart;
143 const char *InlineAsmEnd;
145 /// These are assembly directives that tells the assembler to interpret the
146 /// following instructions differently. Defaults to ".code16", ".code32",
148 const char *Code16Directive;
149 const char *Code32Directive;
150 const char *Code64Directive;
152 /// Which dialect of an assembler variant to use. Defaults to 0
153 unsigned AssemblerDialect = 0;
155 /// This is true if the assembler allows @ characters in symbol names.
156 /// Defaults to false.
157 bool AllowAtInName = false;
159 /// If this is true, symbol names with invalid characters will be printed in
161 bool SupportsQuotedNames = true;
163 /// This is true if data region markers should be printed as
164 /// ".data_region/.end_data_region" directives. If false, use "$d/$a" labels
166 bool UseDataRegionDirectives = false;
168 //===--- Data Emission Directives -------------------------------------===//
170 /// This should be set to the directive used to get some number of zero bytes
171 /// emitted to the current section. Common cases are "\t.zero\t" and
172 /// "\t.space\t". If this is set to null, the Data*bitsDirective's will be
173 /// used to emit zero bytes. Defaults to "\t.zero\t"
174 const char *ZeroDirective;
176 /// This directive allows emission of an ascii string with the standard C
177 /// escape characters embedded into it. If a target doesn't support this, it
178 /// can be set to null. Defaults to "\t.ascii\t"
179 const char *AsciiDirective;
181 /// If not null, this allows for special handling of zero terminated strings
182 /// on this target. This is commonly supported as ".asciz". If a target
183 /// doesn't support this, it can be set to null. Defaults to "\t.asciz\t"
184 const char *AscizDirective;
186 /// These directives are used to output some unit of integer data to the
187 /// current section. If a data directive is set to null, smaller data
188 /// directives will be used to emit the large sizes. Defaults to "\t.byte\t",
189 /// "\t.short\t", "\t.long\t", "\t.quad\t"
190 const char *Data8bitsDirective;
191 const char *Data16bitsDirective;
192 const char *Data32bitsDirective;
193 const char *Data64bitsDirective;
195 /// If non-null, a directive that is used to emit a word which should be
196 /// relocated as a 64-bit GP-relative offset, e.g. .gpdword on Mips. Defaults
198 const char *GPRel64Directive = nullptr;
200 /// If non-null, a directive that is used to emit a word which should be
201 /// relocated as a 32-bit GP-relative offset, e.g. .gpword on Mips or .gprel32
202 /// on Alpha. Defaults to nullptr.
203 const char *GPRel32Directive = nullptr;
205 /// If non-null, directives that are used to emit a word/dword which should
206 /// be relocated as a 32/64-bit DTP/TP-relative offset, e.g. .dtprelword/
207 /// .dtpreldword/.tprelword/.tpreldword on Mips.
208 const char *DTPRel32Directive = nullptr;
209 const char *DTPRel64Directive = nullptr;
210 const char *TPRel32Directive = nullptr;
211 const char *TPRel64Directive = nullptr;
213 /// This is true if this target uses "Sun Style" syntax for section switching
214 /// ("#alloc,#write" etc) instead of the normal ELF syntax (,"a,w") in
215 /// .section directives. Defaults to false.
216 bool SunStyleELFSectionSwitchSyntax = false;
218 /// This is true if this target uses ELF '.section' directive before the
219 /// '.bss' one. It's used for PPC/Linux which doesn't support the '.bss'
220 /// directive only. Defaults to false.
221 bool UsesELFSectionDirectiveForBSS = false;
223 bool NeedsDwarfSectionOffsetDirective = false;
225 //===--- Alignment Information ----------------------------------------===//
227 /// If this is true (the default) then the asmprinter emits ".align N"
228 /// directives, where N is the number of bytes to align to. Otherwise, it
229 /// emits ".align log2(N)", e.g. 3 to align to an 8 byte boundary. Defaults
231 bool AlignmentIsInBytes = true;
233 /// If non-zero, this is used to fill the executable space created as the
234 /// result of a alignment directive. Defaults to 0
235 unsigned TextAlignFillValue = 0;
237 //===--- Global Variable Emission Directives --------------------------===//
239 /// This is the directive used to declare a global entity. Defaults to
241 const char *GlobalDirective;
243 /// True if the expression
245 /// uses a relocation but it can be suppressed by writing
248 bool SetDirectiveSuppressesReloc = false;
250 /// False if the assembler requires that we use
262 /// Defaults to true.
263 bool HasAggressiveSymbolFolding = true;
265 /// True is .comm's and .lcomms optional alignment is to be specified in bytes
266 /// instead of log2(n). Defaults to true.
267 bool COMMDirectiveAlignmentIsInBytes = true;
269 /// Describes if the .lcomm directive for the target supports an alignment
270 /// argument and how it is interpreted. Defaults to NoAlignment.
271 LCOMM::LCOMMType LCOMMDirectiveAlignmentType = LCOMM::NoAlignment;
273 // True if the target allows .align directives on functions. This is true for
274 // most targets, so defaults to true.
275 bool HasFunctionAlignment = true;
277 /// True if the target has .type and .size directives, this is true for most
278 /// ELF targets. Defaults to true.
279 bool HasDotTypeDotSizeDirective = true;
281 /// True if the target has a single parameter .file directive, this is true
282 /// for ELF targets. Defaults to true.
283 bool HasSingleParameterDotFile = true;
285 /// True if the target has a .ident directive, this is true for ELF targets.
286 /// Defaults to false.
287 bool HasIdentDirective = false;
289 /// True if this target supports the MachO .no_dead_strip directive. Defaults
291 bool HasNoDeadStrip = false;
293 /// True if this target supports the MachO .alt_entry directive. Defaults to
295 bool HasAltEntry = false;
297 /// Used to declare a global as being a weak symbol. Defaults to ".weak".
298 const char *WeakDirective;
300 /// This directive, if non-null, is used to declare a global as being a weak
301 /// undefined symbol. Defaults to nullptr.
302 const char *WeakRefDirective = nullptr;
304 /// True if we have a directive to declare a global as being a weak defined
305 /// symbol. Defaults to false.
306 bool HasWeakDefDirective = false;
308 /// True if we have a directive to declare a global as being a weak defined
309 /// symbol that can be hidden (unexported). Defaults to false.
310 bool HasWeakDefCanBeHiddenDirective = false;
312 /// True if we have a .linkonce directive. This is used on cygwin/mingw.
313 /// Defaults to false.
314 bool HasLinkOnceDirective = false;
316 /// This attribute, if not MCSA_Invalid, is used to declare a symbol as having
317 /// hidden visibility. Defaults to MCSA_Hidden.
318 MCSymbolAttr HiddenVisibilityAttr = MCSA_Hidden;
320 /// This attribute, if not MCSA_Invalid, is used to declare an undefined
321 /// symbol as having hidden visibility. Defaults to MCSA_Hidden.
322 MCSymbolAttr HiddenDeclarationVisibilityAttr = MCSA_Hidden;
324 /// This attribute, if not MCSA_Invalid, is used to declare a symbol as having
325 /// protected visibility. Defaults to MCSA_Protected
326 MCSymbolAttr ProtectedVisibilityAttr = MCSA_Protected;
328 //===--- Dwarf Emission Directives -----------------------------------===//
330 /// True if target supports emission of debugging information. Defaults to
332 bool SupportsDebugInformation = false;
334 /// Exception handling format for the target. Defaults to None.
335 ExceptionHandling ExceptionsType = ExceptionHandling::None;
337 /// Windows exception handling data (.pdata) encoding. Defaults to Invalid.
338 WinEH::EncodingType WinEHEncodingType = WinEH::EncodingType::Invalid;
340 /// True if Dwarf2 output generally uses relocations for references to other
341 /// .debug_* sections.
342 bool DwarfUsesRelocationsAcrossSections = true;
344 /// True if DWARF FDE symbol reference relocations should be replaced by an
345 /// absolute difference.
346 bool DwarfFDESymbolsUseAbsDiff = false;
348 /// True if dwarf register numbers are printed instead of symbolic register
349 /// names in .cfi_* directives. Defaults to false.
350 bool DwarfRegNumForCFI = false;
352 /// True if target uses parens to indicate the symbol variant instead of @.
353 /// For example, foo(plt) instead of foo@plt. Defaults to false.
354 bool UseParensForSymbolVariant = false;
356 /// True if the target supports flags in ".loc" directive, false if only
357 /// location is allowed.
358 bool SupportsExtendedDwarfLocDirective = true;
360 //===--- Prologue State ----------------------------------------------===//
362 std::vector<MCCFIInstruction> InitialFrameState;
364 //===--- Integrated Assembler Information ----------------------------===//
366 /// Should we use the integrated assembler?
367 /// The integrated assembler should be enabled by default (by the
368 /// constructors) when failing to parse a valid piece of assembly (inline
369 /// or otherwise) is considered a bug. It may then be overridden after
370 /// construction (see LLVMTargetMachine::initAsmInfo()).
371 bool UseIntegratedAssembler;
373 /// Preserve Comments in assembly
374 bool PreserveAsmComments;
376 /// Compress DWARF debug sections. Defaults to no compression.
377 DebugCompressionType CompressDebugSections = DebugCompressionType::None;
379 /// True if the integrated assembler should interpret 'a >> b' constant
380 /// expressions as logical rather than arithmetic.
381 bool UseLogicalShr = true;
383 // If true, emit GOTPCRELX/REX_GOTPCRELX instead of GOTPCREL, on
385 bool RelaxELFRelocations = true;
387 // If true, then the lexer and expression parser will support %neg(),
388 // %hi(), and similar unary operators.
389 bool HasMipsExpressions = false;
392 explicit MCAsmInfo();
393 virtual ~MCAsmInfo();
395 /// Get the code pointer size in bytes.
396 unsigned getCodePointerSize() const { return CodePointerSize; }
398 /// Get the callee-saved register stack slot
400 unsigned getCalleeSaveStackSlotSize() const {
401 return CalleeSaveStackSlotSize;
404 /// True if the target is little endian.
405 bool isLittleEndian() const { return IsLittleEndian; }
407 /// True if target stack grow up.
408 bool isStackGrowthDirectionUp() const { return StackGrowsUp; }
410 bool hasSubsectionsViaSymbols() const { return HasSubsectionsViaSymbols; }
412 // Data directive accessors.
414 const char *getData8bitsDirective() const { return Data8bitsDirective; }
415 const char *getData16bitsDirective() const { return Data16bitsDirective; }
416 const char *getData32bitsDirective() const { return Data32bitsDirective; }
417 const char *getData64bitsDirective() const { return Data64bitsDirective; }
418 const char *getGPRel64Directive() const { return GPRel64Directive; }
419 const char *getGPRel32Directive() const { return GPRel32Directive; }
420 const char *getDTPRel64Directive() const { return DTPRel64Directive; }
421 const char *getDTPRel32Directive() const { return DTPRel32Directive; }
422 const char *getTPRel64Directive() const { return TPRel64Directive; }
423 const char *getTPRel32Directive() const { return TPRel32Directive; }
425 /// Targets can implement this method to specify a section to switch to if the
426 /// translation unit doesn't have any trampolines that require an executable
428 virtual MCSection *getNonexecutableStackSection(MCContext &Ctx) const {
432 /// True if the section is atomized using the symbols in it.
433 /// This is false if the section is not atomized at all (most ELF sections) or
434 /// if it is atomized based on its contents (MachO' __TEXT,__cstring for
436 virtual bool isSectionAtomizableBySymbols(const MCSection &Section) const;
438 virtual const MCExpr *getExprForPersonalitySymbol(const MCSymbol *Sym,
440 MCStreamer &Streamer) const;
442 virtual const MCExpr *getExprForFDESymbol(const MCSymbol *Sym,
444 MCStreamer &Streamer) const;
446 /// Return true if the identifier \p Name does not need quotes to be
447 /// syntactically correct.
448 virtual bool isValidUnquotedName(StringRef Name) const;
450 /// Return true if the .section directive should be omitted when
451 /// emitting \p SectionName. For example:
453 /// shouldOmitSectionDirective(".text")
455 /// returns false => .section .text,#alloc,#execinstr
456 /// returns true => .text
457 virtual bool shouldOmitSectionDirective(StringRef SectionName) const;
459 bool usesSunStyleELFSectionSwitchSyntax() const {
460 return SunStyleELFSectionSwitchSyntax;
463 bool usesELFSectionDirectiveForBSS() const {
464 return UsesELFSectionDirectiveForBSS;
467 bool needsDwarfSectionOffsetDirective() const {
468 return NeedsDwarfSectionOffsetDirective;
473 bool hasMachoZeroFillDirective() const { return HasMachoZeroFillDirective; }
474 bool hasMachoTBSSDirective() const { return HasMachoTBSSDirective; }
475 bool hasCOFFAssociativeComdats() const { return HasCOFFAssociativeComdats; }
476 bool hasCOFFComdatConstants() const { return HasCOFFComdatConstants; }
477 unsigned getMaxInstLength() const { return MaxInstLength; }
478 unsigned getMinInstAlignment() const { return MinInstAlignment; }
479 bool getDollarIsPC() const { return DollarIsPC; }
480 const char *getSeparatorString() const { return SeparatorString; }
482 /// This indicates the column (zero-based) at which asm comments should be
484 unsigned getCommentColumn() const { return 40; }
486 StringRef getCommentString() const { return CommentString; }
487 const char *getLabelSuffix() const { return LabelSuffix; }
489 bool useAssignmentForEHBegin() const { return UseAssignmentForEHBegin; }
490 bool needsLocalForSize() const { return NeedsLocalForSize; }
491 StringRef getPrivateGlobalPrefix() const { return PrivateGlobalPrefix; }
492 StringRef getPrivateLabelPrefix() const { return PrivateLabelPrefix; }
494 bool hasLinkerPrivateGlobalPrefix() const {
495 return LinkerPrivateGlobalPrefix[0] != '\0';
498 StringRef getLinkerPrivateGlobalPrefix() const {
499 if (hasLinkerPrivateGlobalPrefix())
500 return LinkerPrivateGlobalPrefix;
501 return getPrivateGlobalPrefix();
504 const char *getInlineAsmStart() const { return InlineAsmStart; }
505 const char *getInlineAsmEnd() const { return InlineAsmEnd; }
506 const char *getCode16Directive() const { return Code16Directive; }
507 const char *getCode32Directive() const { return Code32Directive; }
508 const char *getCode64Directive() const { return Code64Directive; }
509 unsigned getAssemblerDialect() const { return AssemblerDialect; }
510 bool doesAllowAtInName() const { return AllowAtInName; }
511 bool supportsNameQuoting() const { return SupportsQuotedNames; }
513 bool doesSupportDataRegionDirectives() const {
514 return UseDataRegionDirectives;
517 const char *getZeroDirective() const { return ZeroDirective; }
518 const char *getAsciiDirective() const { return AsciiDirective; }
519 const char *getAscizDirective() const { return AscizDirective; }
520 bool getAlignmentIsInBytes() const { return AlignmentIsInBytes; }
521 unsigned getTextAlignFillValue() const { return TextAlignFillValue; }
522 const char *getGlobalDirective() const { return GlobalDirective; }
524 bool doesSetDirectiveSuppressReloc() const {
525 return SetDirectiveSuppressesReloc;
528 bool hasAggressiveSymbolFolding() const { return HasAggressiveSymbolFolding; }
530 bool getCOMMDirectiveAlignmentIsInBytes() const {
531 return COMMDirectiveAlignmentIsInBytes;
534 LCOMM::LCOMMType getLCOMMDirectiveAlignmentType() const {
535 return LCOMMDirectiveAlignmentType;
538 bool hasFunctionAlignment() const { return HasFunctionAlignment; }
539 bool hasDotTypeDotSizeDirective() const { return HasDotTypeDotSizeDirective; }
540 bool hasSingleParameterDotFile() const { return HasSingleParameterDotFile; }
541 bool hasIdentDirective() const { return HasIdentDirective; }
542 bool hasNoDeadStrip() const { return HasNoDeadStrip; }
543 bool hasAltEntry() const { return HasAltEntry; }
544 const char *getWeakDirective() const { return WeakDirective; }
545 const char *getWeakRefDirective() const { return WeakRefDirective; }
546 bool hasWeakDefDirective() const { return HasWeakDefDirective; }
548 bool hasWeakDefCanBeHiddenDirective() const {
549 return HasWeakDefCanBeHiddenDirective;
552 bool hasLinkOnceDirective() const { return HasLinkOnceDirective; }
554 MCSymbolAttr getHiddenVisibilityAttr() const { return HiddenVisibilityAttr; }
556 MCSymbolAttr getHiddenDeclarationVisibilityAttr() const {
557 return HiddenDeclarationVisibilityAttr;
560 MCSymbolAttr getProtectedVisibilityAttr() const {
561 return ProtectedVisibilityAttr;
564 bool doesSupportDebugInformation() const { return SupportsDebugInformation; }
566 bool doesSupportExceptionHandling() const {
567 return ExceptionsType != ExceptionHandling::None;
570 ExceptionHandling getExceptionHandlingType() const { return ExceptionsType; }
571 WinEH::EncodingType getWinEHEncodingType() const { return WinEHEncodingType; }
573 void setExceptionsType(ExceptionHandling EH) {
577 /// Returns true if the exception handling method for the platform uses call
578 /// frame information to unwind.
579 bool usesCFIForEH() const {
580 return (ExceptionsType == ExceptionHandling::DwarfCFI ||
581 ExceptionsType == ExceptionHandling::ARM || usesWindowsCFI());
584 bool usesWindowsCFI() const {
585 return ExceptionsType == ExceptionHandling::WinEH &&
586 (WinEHEncodingType != WinEH::EncodingType::Invalid &&
587 WinEHEncodingType != WinEH::EncodingType::X86);
590 bool doesDwarfUseRelocationsAcrossSections() const {
591 return DwarfUsesRelocationsAcrossSections;
594 bool doDwarfFDESymbolsUseAbsDiff() const { return DwarfFDESymbolsUseAbsDiff; }
595 bool useDwarfRegNumForCFI() const { return DwarfRegNumForCFI; }
596 bool useParensForSymbolVariant() const { return UseParensForSymbolVariant; }
597 bool supportsExtendedDwarfLocDirective() const {
598 return SupportsExtendedDwarfLocDirective;
601 void addInitialFrameState(const MCCFIInstruction &Inst) {
602 InitialFrameState.push_back(Inst);
605 const std::vector<MCCFIInstruction> &getInitialFrameState() const {
606 return InitialFrameState;
609 /// Return true if assembly (inline or otherwise) should be parsed.
610 bool useIntegratedAssembler() const { return UseIntegratedAssembler; }
612 /// Set whether assembly (inline or otherwise) should be parsed.
613 virtual void setUseIntegratedAssembler(bool Value) {
614 UseIntegratedAssembler = Value;
617 /// Return true if assembly (inline or otherwise) should be parsed.
618 bool preserveAsmComments() const { return PreserveAsmComments; }
620 /// Set whether assembly (inline or otherwise) should be parsed.
621 virtual void setPreserveAsmComments(bool Value) {
622 PreserveAsmComments = Value;
625 DebugCompressionType compressDebugSections() const {
626 return CompressDebugSections;
629 void setCompressDebugSections(DebugCompressionType CompressDebugSections) {
630 this->CompressDebugSections = CompressDebugSections;
633 bool shouldUseLogicalShr() const { return UseLogicalShr; }
635 bool canRelaxRelocations() const { return RelaxELFRelocations; }
636 void setRelaxELFRelocations(bool V) { RelaxELFRelocations = V; }
637 bool hasMipsExpressions() const { return HasMipsExpressions; }
640 } // end namespace llvm
642 #endif // LLVM_MC_MCASMINFO_H