Bug Summary

File:include/llvm/MC/MCAsmInfo.h
Location:line 64, column 7
Description:Excessive padding in 'class llvm::MCAsmInfo' (32 padding bytes, where 0 is optimal). Consider reordering the fields or adding explicit padding members

Annotated Source Code

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 <cassert>
22#include <vector>
23
24namespace llvm {
25class MCExpr;
26class MCSection;
27class MCStreamer;
28class MCSymbol;
29class MCContext;
30
31namespace WinEH {
32enum class EncodingType {
33 Invalid, /// Invalid
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
40 MIPS = 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
56enum class DebugCompressionType {
57 DCT_None, // no compression
58 DCT_Zlib, // zlib style complession
59 DCT_ZlibGnu // zlib-gnu style compression
60};
61
62/// This class is intended to be used as a base class for asm
63/// properties and features specific to the target.
64class MCAsmInfo {
Excessive padding in 'class llvm::MCAsmInfo' (32 padding bytes, where 0 is optimal). Consider reordering the fields or adding explicit padding members
65protected:
66 //===------------------------------------------------------------------===//
67 // Properties to be set by the target writer, used to configure asm printer.
68 //
69
70 /// Pointer size in bytes. Default is 4.
71 unsigned PointerSize;
72
73 /// Size of the stack slot reserved for callee-saved registers, in bytes.
74 /// Default is same as pointer size.
75 unsigned CalleeSaveStackSlotSize;
76
77 /// True if target is little endian. Default is true.
78 bool IsLittleEndian;
79
80 /// True if target stack grow up. Default is false.
81 bool StackGrowsUp;
82
83 /// True if this target has the MachO .subsections_via_symbols directive.
84 /// Default is false.
85 bool HasSubsectionsViaSymbols;
86
87 /// True if this is a MachO target that supports the macho-specific .zerofill
88 /// directive for emitting BSS Symbols. Default is false.
89 bool HasMachoZeroFillDirective;
90
91 /// True if this is a MachO target that supports the macho-specific .tbss
92 /// directive for emitting thread local BSS Symbols. Default is false.
93 bool HasMachoTBSSDirective;
94
95 /// True if the compiler should emit a ".reference .constructors_used" or
96 /// ".reference .destructors_used" directive after the static ctor/dtor
97 /// list. This directive is only emitted in Static relocation model. Default
98 /// is false.
99 bool HasStaticCtorDtorReferenceInStaticMode;
100
101 /// This is the maximum possible length of an instruction, which is needed to
102 /// compute the size of an inline asm. Defaults to 4.
103 unsigned MaxInstLength;
104
105 /// Every possible instruction length is a multiple of this value. Factored
106 /// out in .debug_frame and .debug_line. Defaults to 1.
107 unsigned MinInstAlignment;
108
109 /// The '$' token, when not referencing an identifier or constant, refers to
110 /// the current PC. Defaults to false.
111 bool DollarIsPC;
112
113 /// This string, if specified, is used to separate instructions from each
114 /// other when on the same line. Defaults to ';'
115 const char *SeparatorString;
116
117 /// This indicates the comment character used by the assembler. Defaults to
118 /// "#"
119 const char *CommentString;
120
121 /// This is appended to emitted labels. Defaults to ":"
122 const char *LabelSuffix;
123
124 // Print the EH begin symbol with an assignment. Defaults to false.
125 bool UseAssignmentForEHBegin;
126
127 // Do we need to create a local symbol for .size?
128 bool NeedsLocalForSize;
129
130 /// This prefix is used for globals like constant pool entries that are
131 /// completely private to the .s file and should not have names in the .o
132 /// file. Defaults to "L"
133 const char *PrivateGlobalPrefix;
134
135 /// This prefix is used for labels for basic blocks. Defaults to the same as
136 /// PrivateGlobalPrefix.
137 const char *PrivateLabelPrefix;
138
139 /// This prefix is used for symbols that should be passed through the
140 /// assembler but be removed by the linker. This is 'l' on Darwin, currently
141 /// used for some ObjC metadata. The default of "" meast that for this system
142 /// a plain private symbol should be used. Defaults to "".
143 const char *LinkerPrivateGlobalPrefix;
144
145 /// If these are nonempty, they contain a directive to emit before and after
146 /// an inline assembly statement. Defaults to "#APP\n", "#NO_APP\n"
147 const char *InlineAsmStart;
148 const char *InlineAsmEnd;
149
150 /// These are assembly directives that tells the assembler to interpret the
151 /// following instructions differently. Defaults to ".code16", ".code32",
152 /// ".code64".
153 const char *Code16Directive;
154 const char *Code32Directive;
155 const char *Code64Directive;
156
157 /// Which dialect of an assembler variant to use. Defaults to 0
158 unsigned AssemblerDialect;
159
160 /// This is true if the assembler allows @ characters in symbol names.
161 /// Defaults to false.
162 bool AllowAtInName;
163
164 /// If this is true, symbol names with invalid characters will be printed in
165 /// quotes.
166 bool SupportsQuotedNames;
167
168 /// This is true if data region markers should be printed as
169 /// ".data_region/.end_data_region" directives. If false, use "$d/$a" labels
170 /// instead.
171 bool UseDataRegionDirectives;
172
173 //===--- Data Emission Directives -------------------------------------===//
174
175 /// This should be set to the directive used to get some number of zero bytes
176 /// emitted to the current section. Common cases are "\t.zero\t" and
177 /// "\t.space\t". If this is set to null, the Data*bitsDirective's will be
178 /// used to emit zero bytes. Defaults to "\t.zero\t"
179 const char *ZeroDirective;
180
181 /// This directive allows emission of an ascii string with the standard C
182 /// escape characters embedded into it. Defaults to "\t.ascii\t"
183 const char *AsciiDirective;
184
185 /// If not null, this allows for special handling of zero terminated strings
186 /// on this target. This is commonly supported as ".asciz". If a target
187 /// doesn't support this, it can be set to null. Defaults to "\t.asciz\t"
188 const char *AscizDirective;
189
190 /// These directives are used to output some unit of integer data to the
191 /// current section. If a data directive is set to null, smaller data
192 /// directives will be used to emit the large sizes. Defaults to "\t.byte\t",
193 /// "\t.short\t", "\t.long\t", "\t.quad\t"
194 const char *Data8bitsDirective;
195 const char *Data16bitsDirective;
196 const char *Data32bitsDirective;
197 const char *Data64bitsDirective;
198
199 /// If non-null, a directive that is used to emit a word which should be
200 /// relocated as a 64-bit GP-relative offset, e.g. .gpdword on Mips. Defaults
201 /// to NULL.
202 const char *GPRel64Directive;
203
204 /// If non-null, a directive that is used to emit a word which should be
205 /// relocated as a 32-bit GP-relative offset, e.g. .gpword on Mips or .gprel32
206 /// on Alpha. Defaults to NULL.
207 const char *GPRel32Directive;
208
209 /// This is true if this target uses "Sun Style" syntax for section switching
210 /// ("#alloc,#write" etc) instead of the normal ELF syntax (,"a,w") in
211 /// .section directives. Defaults to false.
212 bool SunStyleELFSectionSwitchSyntax;
213
214 /// This is true if this target uses ELF '.section' directive before the
215 /// '.bss' one. It's used for PPC/Linux which doesn't support the '.bss'
216 /// directive only. Defaults to false.
217 bool UsesELFSectionDirectiveForBSS;
218
219 bool NeedsDwarfSectionOffsetDirective;
220
221 //===--- Alignment Information ----------------------------------------===//
222
223 /// If this is true (the default) then the asmprinter emits ".align N"
224 /// directives, where N is the number of bytes to align to. Otherwise, it
225 /// emits ".align log2(N)", e.g. 3 to align to an 8 byte boundary. Defaults
226 /// to true.
227 bool AlignmentIsInBytes;
228
229 /// If non-zero, this is used to fill the executable space created as the
230 /// result of a alignment directive. Defaults to 0
231 unsigned TextAlignFillValue;
232
233 //===--- Global Variable Emission Directives --------------------------===//
234
235 /// This is the directive used to declare a global entity. Defaults to
236 /// ".globl".
237 const char *GlobalDirective;
238
239 /// True if the expression
240 /// .long f - g
241 /// uses a relocation but it can be suppressed by writing
242 /// a = f - g
243 /// .long a
244 bool SetDirectiveSuppressesReloc;
245
246 /// False if the assembler requires that we use
247 /// \code
248 /// Lc = a - b
249 /// .long Lc
250 /// \endcode
251 //
252 /// instead of
253 //
254 /// \code
255 /// .long a - b
256 /// \endcode
257 ///
258 /// Defaults to true.
259 bool HasAggressiveSymbolFolding;
260
261 /// True is .comm's and .lcomms optional alignment is to be specified in bytes
262 /// instead of log2(n). Defaults to true.
263 bool COMMDirectiveAlignmentIsInBytes;
264
265 /// Describes if the .lcomm directive for the target supports an alignment
266 /// argument and how it is interpreted. Defaults to NoAlignment.
267 LCOMM::LCOMMType LCOMMDirectiveAlignmentType;
268
269 // True if the target allows .align directives on functions. This is true for
270 // most targets, so defaults to true.
271 bool HasFunctionAlignment;
272
273 /// True if the target has .type and .size directives, this is true for most
274 /// ELF targets. Defaults to true.
275 bool HasDotTypeDotSizeDirective;
276
277 /// True if the target has a single parameter .file directive, this is true
278 /// for ELF targets. Defaults to true.
279 bool HasSingleParameterDotFile;
280
281 /// True if the target has a .ident directive, this is true for ELF targets.
282 /// Defaults to false.
283 bool HasIdentDirective;
284
285 /// True if this target supports the MachO .no_dead_strip directive. Defaults
286 /// to false.
287 bool HasNoDeadStrip;
288
289 /// True if this target supports the MachO .alt_entry directive. Defaults to
290 /// false.
291 bool HasAltEntry;
292
293 /// Used to declare a global as being a weak symbol. Defaults to ".weak".
294 const char *WeakDirective;
295
296 /// This directive, if non-null, is used to declare a global as being a weak
297 /// undefined symbol. Defaults to NULL.
298 const char *WeakRefDirective;
299
300 /// True if we have a directive to declare a global as being a weak defined
301 /// symbol. Defaults to false.
302 bool HasWeakDefDirective;
303
304 /// True if we have a directive to declare a global as being a weak defined
305 /// symbol that can be hidden (unexported). Defaults to false.
306 bool HasWeakDefCanBeHiddenDirective;
307
308 /// True if we have a .linkonce directive. This is used on cygwin/mingw.
309 /// Defaults to false.
310 bool HasLinkOnceDirective;
311
312 /// This attribute, if not MCSA_Invalid, is used to declare a symbol as having
313 /// hidden visibility. Defaults to MCSA_Hidden.
314 MCSymbolAttr HiddenVisibilityAttr;
315
316 /// This attribute, if not MCSA_Invalid, is used to declare an undefined
317 /// symbol as having hidden visibility. Defaults to MCSA_Hidden.
318 MCSymbolAttr HiddenDeclarationVisibilityAttr;
319
320 /// This attribute, if not MCSA_Invalid, is used to declare a symbol as having
321 /// protected visibility. Defaults to MCSA_Protected
322 MCSymbolAttr ProtectedVisibilityAttr;
323
324 //===--- Dwarf Emission Directives -----------------------------------===//
325
326 /// True if target supports emission of debugging information. Defaults to
327 /// false.
328 bool SupportsDebugInformation;
329
330 /// Exception handling format for the target. Defaults to None.
331 ExceptionHandling ExceptionsType;
332
333 /// Windows exception handling data (.pdata) encoding. Defaults to Invalid.
334 WinEH::EncodingType WinEHEncodingType;
335
336 /// True if Dwarf2 output generally uses relocations for references to other
337 /// .debug_* sections.
338 bool DwarfUsesRelocationsAcrossSections;
339
340 /// True if DWARF FDE symbol reference relocations should be replaced by an
341 /// absolute difference.
342 bool DwarfFDESymbolsUseAbsDiff;
343
344 /// True if dwarf register numbers are printed instead of symbolic register
345 /// names in .cfi_* directives. Defaults to false.
346 bool DwarfRegNumForCFI;
347
348 /// True if target uses parens to indicate the symbol variant instead of @.
349 /// For example, foo(plt) instead of foo@plt. Defaults to false.
350 bool UseParensForSymbolVariant;
351
352 //===--- Prologue State ----------------------------------------------===//
353
354 std::vector<MCCFIInstruction> InitialFrameState;
355
356 //===--- Integrated Assembler Information ----------------------------===//
357
358 /// Should we use the integrated assembler?
359 /// The integrated assembler should be enabled by default (by the
360 /// constructors) when failing to parse a valid piece of assembly (inline
361 /// or otherwise) is considered a bug. It may then be overridden after
362 /// construction (see LLVMTargetMachine::initAsmInfo()).
363 bool UseIntegratedAssembler;
364
365 /// Compress DWARF debug sections. Defaults to no compression.
366 DebugCompressionType CompressDebugSections;
367
368 /// True if the integrated assembler should interpret 'a >> b' constant
369 /// expressions as logical rather than arithmetic.
370 bool UseLogicalShr;
371
372 // If true, emit GOTPCRELX/REX_GOTPCRELX instead of GOTPCREL, on
373 // X86_64 ELF.
374 bool RelaxELFRelocations = false;
375
376public:
377 explicit MCAsmInfo();
378 virtual ~MCAsmInfo();
379
380 /// Get the pointer size in bytes.
381 unsigned getPointerSize() const { return PointerSize; }
382
383 /// Get the callee-saved register stack slot
384 /// size in bytes.
385 unsigned getCalleeSaveStackSlotSize() const {
386 return CalleeSaveStackSlotSize;
387 }
388
389 /// True if the target is little endian.
390 bool isLittleEndian() const { return IsLittleEndian; }
391
392 /// True if target stack grow up.
393 bool isStackGrowthDirectionUp() const { return StackGrowsUp; }
394
395 bool hasSubsectionsViaSymbols() const { return HasSubsectionsViaSymbols; }
396
397 // Data directive accessors.
398
399 const char *getData8bitsDirective() const { return Data8bitsDirective; }
400 const char *getData16bitsDirective() const { return Data16bitsDirective; }
401 const char *getData32bitsDirective() const { return Data32bitsDirective; }
402 const char *getData64bitsDirective() const { return Data64bitsDirective; }
403 const char *getGPRel64Directive() const { return GPRel64Directive; }
404 const char *getGPRel32Directive() const { return GPRel32Directive; }
405
406 /// Targets can implement this method to specify a section to switch to if the
407 /// translation unit doesn't have any trampolines that require an executable
408 /// stack.
409 virtual MCSection *getNonexecutableStackSection(MCContext &Ctx) const {
410 return nullptr;
411 }
412
413 /// \brief True if the section is atomized using the symbols in it.
414 /// This is false if the section is not atomized at all (most ELF sections) or
415 /// if it is atomized based on its contents (MachO' __TEXT,__cstring for
416 /// example).
417 virtual bool isSectionAtomizableBySymbols(const MCSection &Section) const;
418
419 virtual const MCExpr *getExprForPersonalitySymbol(const MCSymbol *Sym,
420 unsigned Encoding,
421 MCStreamer &Streamer) const;
422
423 virtual const MCExpr *getExprForFDESymbol(const MCSymbol *Sym,
424 unsigned Encoding,
425 MCStreamer &Streamer) const;
426
427 /// Return true if the identifier \p Name does not need quotes to be
428 /// syntactically correct.
429 virtual bool isValidUnquotedName(StringRef Name) const;
430
431 /// Return true if the .section directive should be omitted when
432 /// emitting \p SectionName. For example:
433 ///
434 /// shouldOmitSectionDirective(".text")
435 ///
436 /// returns false => .section .text,#alloc,#execinstr
437 /// returns true => .text
438 virtual bool shouldOmitSectionDirective(StringRef SectionName) const;
439
440 bool usesSunStyleELFSectionSwitchSyntax() const {
441 return SunStyleELFSectionSwitchSyntax;
442 }
443
444 bool usesELFSectionDirectiveForBSS() const {
445 return UsesELFSectionDirectiveForBSS;
446 }
447
448 bool needsDwarfSectionOffsetDirective() const {
449 return NeedsDwarfSectionOffsetDirective;
450 }
451
452 // Accessors.
453
454 bool hasMachoZeroFillDirective() const { return HasMachoZeroFillDirective; }
455 bool hasMachoTBSSDirective() const { return HasMachoTBSSDirective; }
456 bool hasStaticCtorDtorReferenceInStaticMode() const {
457 return HasStaticCtorDtorReferenceInStaticMode;
458 }
459 unsigned getMaxInstLength() const { return MaxInstLength; }
460 unsigned getMinInstAlignment() const { return MinInstAlignment; }
461 bool getDollarIsPC() const { return DollarIsPC; }
462 const char *getSeparatorString() const { return SeparatorString; }
463
464 /// This indicates the column (zero-based) at which asm comments should be
465 /// printed.
466 unsigned getCommentColumn() const { return 40; }
467
468 const char *getCommentString() const { return CommentString; }
469 const char *getLabelSuffix() const { return LabelSuffix; }
470
471 bool useAssignmentForEHBegin() const { return UseAssignmentForEHBegin; }
472 bool needsLocalForSize() const { return NeedsLocalForSize; }
473 const char *getPrivateGlobalPrefix() const { return PrivateGlobalPrefix; }
474 const char *getPrivateLabelPrefix() const { return PrivateLabelPrefix; }
475 bool hasLinkerPrivateGlobalPrefix() const {
476 return LinkerPrivateGlobalPrefix[0] != '\0';
477 }
478 const char *getLinkerPrivateGlobalPrefix() const {
479 if (hasLinkerPrivateGlobalPrefix())
480 return LinkerPrivateGlobalPrefix;
481 return getPrivateGlobalPrefix();
482 }
483 const char *getInlineAsmStart() const { return InlineAsmStart; }
484 const char *getInlineAsmEnd() const { return InlineAsmEnd; }
485 const char *getCode16Directive() const { return Code16Directive; }
486 const char *getCode32Directive() const { return Code32Directive; }
487 const char *getCode64Directive() const { return Code64Directive; }
488 unsigned getAssemblerDialect() const { return AssemblerDialect; }
489 bool doesAllowAtInName() const { return AllowAtInName; }
490 bool supportsNameQuoting() const { return SupportsQuotedNames; }
491 bool doesSupportDataRegionDirectives() const {
492 return UseDataRegionDirectives;
493 }
494 const char *getZeroDirective() const { return ZeroDirective; }
495 const char *getAsciiDirective() const { return AsciiDirective; }
496 const char *getAscizDirective() const { return AscizDirective; }
497 bool getAlignmentIsInBytes() const { return AlignmentIsInBytes; }
498 unsigned getTextAlignFillValue() const { return TextAlignFillValue; }
499 const char *getGlobalDirective() const { return GlobalDirective; }
500 bool doesSetDirectiveSuppressesReloc() const {
501 return SetDirectiveSuppressesReloc;
502 }
503 bool hasAggressiveSymbolFolding() const { return HasAggressiveSymbolFolding; }
504 bool getCOMMDirectiveAlignmentIsInBytes() const {
505 return COMMDirectiveAlignmentIsInBytes;
506 }
507 LCOMM::LCOMMType getLCOMMDirectiveAlignmentType() const {
508 return LCOMMDirectiveAlignmentType;
509 }
510 bool hasFunctionAlignment() const { return HasFunctionAlignment; }
511 bool hasDotTypeDotSizeDirective() const { return HasDotTypeDotSizeDirective; }
512 bool hasSingleParameterDotFile() const { return HasSingleParameterDotFile; }
513 bool hasIdentDirective() const { return HasIdentDirective; }
514 bool hasNoDeadStrip() const { return HasNoDeadStrip; }
515 bool hasAltEntry() const { return HasAltEntry; }
516 const char *getWeakDirective() const { return WeakDirective; }
517 const char *getWeakRefDirective() const { return WeakRefDirective; }
518 bool hasWeakDefDirective() const { return HasWeakDefDirective; }
519 bool hasWeakDefCanBeHiddenDirective() const {
520 return HasWeakDefCanBeHiddenDirective;
521 }
522 bool hasLinkOnceDirective() const { return HasLinkOnceDirective; }
523
524 MCSymbolAttr getHiddenVisibilityAttr() const { return HiddenVisibilityAttr; }
525 MCSymbolAttr getHiddenDeclarationVisibilityAttr() const {
526 return HiddenDeclarationVisibilityAttr;
527 }
528 MCSymbolAttr getProtectedVisibilityAttr() const {
529 return ProtectedVisibilityAttr;
530 }
531 bool doesSupportDebugInformation() const { return SupportsDebugInformation; }
532 bool doesSupportExceptionHandling() const {
533 return ExceptionsType != ExceptionHandling::None;
534 }
535 ExceptionHandling getExceptionHandlingType() const { return ExceptionsType; }
536 WinEH::EncodingType getWinEHEncodingType() const { return WinEHEncodingType; }
537
538 /// Returns true if the exception handling method for the platform uses call
539 /// frame information to unwind.
540 bool usesCFIForEH() const {
541 return (ExceptionsType == ExceptionHandling::DwarfCFI ||
542 ExceptionsType == ExceptionHandling::ARM || usesWindowsCFI());
543 }
544
545 bool usesWindowsCFI() const {
546 return ExceptionsType == ExceptionHandling::WinEH &&
547 (WinEHEncodingType != WinEH::EncodingType::Invalid &&
548 WinEHEncodingType != WinEH::EncodingType::X86);
549 }
550
551 bool doesDwarfUseRelocationsAcrossSections() const {
552 return DwarfUsesRelocationsAcrossSections;
553 }
554 bool doDwarfFDESymbolsUseAbsDiff() const { return DwarfFDESymbolsUseAbsDiff; }
555 bool useDwarfRegNumForCFI() const { return DwarfRegNumForCFI; }
556 bool useParensForSymbolVariant() const { return UseParensForSymbolVariant; }
557
558 void addInitialFrameState(const MCCFIInstruction &Inst) {
559 InitialFrameState.push_back(Inst);
560 }
561
562 const std::vector<MCCFIInstruction> &getInitialFrameState() const {
563 return InitialFrameState;
564 }
565
566 /// Return true if assembly (inline or otherwise) should be parsed.
567 bool useIntegratedAssembler() const { return UseIntegratedAssembler; }
568
569 /// Set whether assembly (inline or otherwise) should be parsed.
570 virtual void setUseIntegratedAssembler(bool Value) {
571 UseIntegratedAssembler = Value;
572 }
573
574 DebugCompressionType compressDebugSections() const {
575 return CompressDebugSections;
576 }
577
578 void setCompressDebugSections(DebugCompressionType CompressDebugSections) {
579 this->CompressDebugSections = CompressDebugSections;
580 }
581
582 bool shouldUseLogicalShr() const { return UseLogicalShr; }
583
584 bool canRelaxRelocations() const { return RelaxELFRelocations; }
585 void setRelaxELFRelocations(bool V) { RelaxELFRelocations = V; }
586};
587}
588
589#endif