MCAsmInfo.h revision 5d4918dbd116b0b5e561c431b1ea527ee1b9302a 
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_TARGET_ASM_INFO_H
17#define LLVM_TARGET_ASM_INFO_H
18
19#include "llvm/MC/MCDirectives.h"
20#include <cassert>
21
22namespace llvm {
23  class MCSection;
24  class MCContext;
25
26  /// MCAsmInfo - This class is intended to be used as a base class for asm
27  /// properties and features specific to the target.
28  namespace ExceptionHandling { enum ExceptionsType { None, Dwarf, SjLj }; }
29
30  class MCAsmInfo {
31  protected:
32    //===------------------------------------------------------------------===//
33    // Properties to be set by the target writer, used to configure asm printer.
34    //
35
36    /// HasSubsectionsViaSymbols - True if this target has the MachO
37    /// .subsections_via_symbols directive.
38    bool HasSubsectionsViaSymbols;           // Default is false.
39
40    /// HasMachoZeroFillDirective - True if this is a MachO target that supports
41    /// the macho-specific .zerofill directive for emitting BSS Symbols.
42    bool HasMachoZeroFillDirective;               // Default is false.
43
44    /// HasMachoTBSSDirective - True if this is a MachO target that supports
45    /// the macho-specific .tbss directive for emitting thread local BSS Symbols
46    bool HasMachoTBSSDirective;                 // Default is false.
47
48    /// HasStaticCtorDtorReferenceInStaticMode - True if the compiler should
49    /// emit a ".reference .constructors_used" or ".reference .destructors_used"
50    /// directive after the a static ctor/dtor list.  This directive is only
51    /// emitted in Static relocation model.
52    bool HasStaticCtorDtorReferenceInStaticMode;  // Default is false.
53
54    /// LinkerRequiresNonEmptyDwarfLines - True if the linker has a bug and
55    /// requires that the debug_line section be of a minimum size. In practice
56    /// such a linker requires a non empty line sequence if a file is present.
57    bool LinkerRequiresNonEmptyDwarfLines; // Default to false.
58
59    /// MaxInstLength - This is the maximum possible length of an instruction,
60    /// which is needed to compute the size of an inline asm.
61    unsigned MaxInstLength;                  // Defaults to 4.
62
63    /// PCSymbol - The symbol used to represent the current PC.  Used in PC
64    /// relative expressions.
65    const char *PCSymbol;                    // Defaults to "$".
66
67    /// SeparatorChar - This character, if specified, is used to separate
68    /// instructions from each other when on the same line.  This is used to
69    /// measure inline asm instructions.
70    char SeparatorChar;                      // Defaults to ';'
71
72    /// CommentColumn - This indicates the comment num (zero-based) at
73    /// which asm comments should be printed.
74    unsigned CommentColumn;                  // Defaults to 40
75
76    /// CommentString - This indicates the comment character used by the
77    /// assembler.
78    const char *CommentString;               // Defaults to "#"
79
80    /// LabelSuffix - This is appended to emitted labels.
81    const char *LabelSuffix;                 // Defaults to ":"
82
83    /// GlobalPrefix - If this is set to a non-empty string, it is prepended
84    /// onto all global symbols.  This is often used for "_" or ".".
85    const char *GlobalPrefix;                // Defaults to ""
86
87    /// PrivateGlobalPrefix - This prefix is used for globals like constant
88    /// pool entries that are completely private to the .s file and should not
89    /// have names in the .o file.  This is often "." or "L".
90    const char *PrivateGlobalPrefix;         // Defaults to "."
91
92    /// LinkerPrivateGlobalPrefix - This prefix is used for symbols that should
93    /// be passed through the assembler but be removed by the linker.  This
94    /// is "l" on Darwin, currently used for some ObjC metadata.
95    const char *LinkerPrivateGlobalPrefix;   // Defaults to ""
96
97    /// InlineAsmStart/End - If these are nonempty, they contain a directive to
98    /// emit before and after an inline assembly statement.
99    const char *InlineAsmStart;              // Defaults to "#APP\n"
100    const char *InlineAsmEnd;                // Defaults to "#NO_APP\n"
101
102    /// AssemblerDialect - Which dialect of an assembler variant to use.
103    unsigned AssemblerDialect;               // Defaults to 0
104
105    /// AllowQuotesInName - This is true if the assembler allows for complex
106    /// symbol names to be surrounded in quotes.  This defaults to false.
107    bool AllowQuotesInName;
108
109    /// AllowNameToStartWithDigit - This is true if the assembler allows symbol
110    /// names to start with a digit (e.g., "0x0021").  This defaults to false.
111    bool AllowNameToStartWithDigit;
112
113    /// AllowPeriodsInName - This is true if the assembler allows periods in
114    /// symbol names.  This defaults to true.
115    bool AllowPeriodsInName;
116
117    //===--- Data Emission Directives -------------------------------------===//
118
119    /// ZeroDirective - this should be set to the directive used to get some
120    /// number of zero bytes emitted to the current section.  Common cases are
121    /// "\t.zero\t" and "\t.space\t".  If this is set to null, the
122    /// Data*bitsDirective's will be used to emit zero bytes.
123    const char *ZeroDirective;               // Defaults to "\t.zero\t"
124
125    /// AsciiDirective - This directive allows emission of an ascii string with
126    /// the standard C escape characters embedded into it.
127    const char *AsciiDirective;              // Defaults to "\t.ascii\t"
128
129    /// AscizDirective - If not null, this allows for special handling of
130    /// zero terminated strings on this target.  This is commonly supported as
131    /// ".asciz".  If a target doesn't support this, it can be set to null.
132    const char *AscizDirective;              // Defaults to "\t.asciz\t"
133
134    /// DataDirectives - These directives are used to output some unit of
135    /// integer data to the current section.  If a data directive is set to
136    /// null, smaller data directives will be used to emit the large sizes.
137    const char *Data8bitsDirective;          // Defaults to "\t.byte\t"
138    const char *Data16bitsDirective;         // Defaults to "\t.short\t"
139    const char *Data32bitsDirective;         // Defaults to "\t.long\t"
140    const char *Data64bitsDirective;         // Defaults to "\t.quad\t"
141
142    /// GPRel32Directive - if non-null, a directive that is used to emit a word
143    /// which should be relocated as a 32-bit GP-relative offset, e.g. .gpword
144    /// on Mips or .gprel32 on Alpha.
145    const char *GPRel32Directive;            // Defaults to NULL.
146
147    /// getDataASDirective - Return the directive that should be used to emit
148    /// data of the specified size to the specified numeric address space.
149    virtual const char *getDataASDirective(unsigned Size, unsigned AS) const {
150      assert(AS != 0 && "Don't know the directives for default addr space");
151      return 0;
152    }
153
154    /// SunStyleELFSectionSwitchSyntax - This is true if this target uses "Sun
155    /// Style" syntax for section switching ("#alloc,#write" etc) instead of the
156    /// normal ELF syntax (,"a,w") in .section directives.
157    bool SunStyleELFSectionSwitchSyntax;     // Defaults to false.
158
159    /// UsesELFSectionDirectiveForBSS - This is true if this target uses ELF
160    /// '.section' directive before the '.bss' one. It's used for PPC/Linux
161    /// which doesn't support the '.bss' directive only.
162    bool UsesELFSectionDirectiveForBSS;      // Defaults to false.
163
164    /// HasMicrosoftFastStdCallMangling - True if this target uses microsoft
165    /// style mangling for functions with X86_StdCall/X86_FastCall calling
166    /// convention.
167    bool HasMicrosoftFastStdCallMangling;    // Defaults to false.
168
169    //===--- Alignment Information ----------------------------------------===//
170
171    /// AlignDirective - The directive used to emit round up to an alignment
172    /// boundary.
173    ///
174    const char *AlignDirective;              // Defaults to "\t.align\t"
175
176    /// AlignmentIsInBytes - If this is true (the default) then the asmprinter
177    /// emits ".align N" directives, where N is the number of bytes to align to.
178    /// Otherwise, it emits ".align log2(N)", e.g. 3 to align to an 8 byte
179    /// boundary.
180    bool AlignmentIsInBytes;                 // Defaults to true
181
182    /// TextAlignFillValue - If non-zero, this is used to fill the executable
183    /// space created as the result of a alignment directive.
184    unsigned TextAlignFillValue;             // Defaults to 0
185
186    //===--- Global Variable Emission Directives --------------------------===//
187
188    /// GlobalDirective - This is the directive used to declare a global entity.
189    ///
190    const char *GlobalDirective;             // Defaults to NULL.
191
192    /// ExternDirective - This is the directive used to declare external
193    /// globals.
194    ///
195    const char *ExternDirective;             // Defaults to NULL.
196
197    /// HasSetDirective - True if the assembler supports the .set directive.
198    bool HasSetDirective;                    // Defaults to true.
199
200    /// NeedsSetToChangeDiffSize - True if the assembler requires that we do
201    /// Lc = a - b
202    /// .long Lc
203    /// instead of doing
204    /// .long a - b
205    bool NeedsSetToChangeDiffSize;           // Defaults to false.
206
207    /// HasLCOMMDirective - This is true if the target supports the .lcomm
208    /// directive.
209    bool HasLCOMMDirective;                  // Defaults to false.
210
211    /// COMMDirectiveAlignmentIsInBytes - True is COMMDirective's optional
212    /// alignment is to be specified in bytes instead of log2(n).
213    bool COMMDirectiveAlignmentIsInBytes;    // Defaults to true;
214
215    /// HasDotTypeDotSizeDirective - True if the target has .type and .size
216    /// directives, this is true for most ELF targets.
217    bool HasDotTypeDotSizeDirective;         // Defaults to true.
218
219    /// HasSingleParameterDotFile - True if the target has a single parameter
220    /// .file directive, this is true for ELF targets.
221    bool HasSingleParameterDotFile;          // Defaults to true.
222
223    /// HasNoDeadStrip - True if this target supports the MachO .no_dead_strip
224    /// directive.
225    bool HasNoDeadStrip;                     // Defaults to false.
226
227    /// HasSymbolResolver - True if this target supports the MachO
228    /// .symbol_resolver directive.
229    bool HasSymbolResolver;                     // Defaults to false.
230
231    /// WeakRefDirective - This directive, if non-null, is used to declare a
232    /// global as being a weak undefined symbol.
233    const char *WeakRefDirective;            // Defaults to NULL.
234
235    /// WeakDefDirective - This directive, if non-null, is used to declare a
236    /// global as being a weak defined symbol.
237    const char *WeakDefDirective;            // Defaults to NULL.
238
239    /// LinkOnceDirective - This directive, if non-null is used to declare a
240    /// global as being a weak defined symbol.  This is used on cygwin/mingw.
241    const char *LinkOnceDirective;           // Defaults to NULL.
242
243    /// HiddenVisibilityAttr - This attribute, if not MCSA_Invalid, is used to
244    /// declare a symbol as having hidden visibility.
245    MCSymbolAttr HiddenVisibilityAttr;       // Defaults to MCSA_Hidden.
246
247    /// ProtectedVisibilityAttr - This attribute, if not MCSA_Invalid, is used
248    /// to declare a symbol as having protected visibility.
249    MCSymbolAttr ProtectedVisibilityAttr;    // Defaults to MCSA_Protected
250
251    //===--- Dwarf Emission Directives -----------------------------------===//
252
253    /// HasLEB128 - True if target asm supports leb128 directives.
254    bool HasLEB128;                          // Defaults to false.
255
256    /// SupportsDebugInformation - True if target supports emission of debugging
257    /// information.
258    bool SupportsDebugInformation;           // Defaults to false.
259
260    /// SupportsExceptionHandling - True if target supports exception handling.
261    ExceptionHandling::ExceptionsType ExceptionsType; // Defaults to None
262
263    /// RequiresFrameSection - true if the Dwarf2 output needs a frame section
264    bool DwarfRequiresFrameSection;          // Defaults to true.
265
266    /// DwarfUsesInlineInfoSection - True if DwarfDebugInlineSection is used to
267    /// encode inline subroutine information.
268    bool DwarfUsesInlineInfoSection;         // Defaults to false.
269
270    /// DwarfSectionOffsetDirective - Special section offset directive.
271    const char* DwarfSectionOffsetDirective; // Defaults to NULL
272
273    /// DwarfUsesAbsoluteLabelForStmtList - True if DW_AT_stmt_list needs
274    /// absolute label instead of offset.
275    bool DwarfUsesAbsoluteLabelForStmtList;  // Defaults to true;
276
277    // DwarfUsesLabelOffsetDifference - True if Dwarf2 output can
278    // use EmitLabelOffsetDifference.
279    bool DwarfUsesLabelOffsetForRanges;
280
281    //===--- CBE Asm Translation Table -----------------------------------===//
282
283    const char *const *AsmTransCBE;          // Defaults to empty
284
285  public:
286    explicit MCAsmInfo();
287    virtual ~MCAsmInfo();
288
289    // FIXME: move these methods to DwarfPrinter when the JIT stops using them.
290    static unsigned getSLEB128Size(int Value);
291    static unsigned getULEB128Size(unsigned Value);
292
293    bool hasSubsectionsViaSymbols() const { return HasSubsectionsViaSymbols; }
294
295    // Data directive accessors.
296    //
297    const char *getData8bitsDirective(unsigned AS = 0) const {
298      return AS == 0 ? Data8bitsDirective : getDataASDirective(8, AS);
299    }
300    const char *getData16bitsDirective(unsigned AS = 0) const {
301      return AS == 0 ? Data16bitsDirective : getDataASDirective(16, AS);
302    }
303    const char *getData32bitsDirective(unsigned AS = 0) const {
304      return AS == 0 ? Data32bitsDirective : getDataASDirective(32, AS);
305    }
306    const char *getData64bitsDirective(unsigned AS = 0) const {
307      return AS == 0 ? Data64bitsDirective : getDataASDirective(64, AS);
308    }
309    const char *getGPRel32Directive() const { return GPRel32Directive; }
310
311    /// getNonexecutableStackSection - Targets can implement this method to
312    /// specify a section to switch to if the translation unit doesn't have any
313    /// trampolines that require an executable stack.
314    virtual const MCSection *getNonexecutableStackSection(MCContext &Ctx) const{
315      return 0;
316    }
317
318    bool usesSunStyleELFSectionSwitchSyntax() const {
319      return SunStyleELFSectionSwitchSyntax;
320    }
321
322    bool usesELFSectionDirectiveForBSS() const {
323      return UsesELFSectionDirectiveForBSS;
324    }
325
326    bool hasMicrosoftFastStdCallMangling() const {
327      return HasMicrosoftFastStdCallMangling;
328    }
329
330    // Accessors.
331    //
332    bool hasMachoZeroFillDirective() const { return HasMachoZeroFillDirective; }
333    bool hasMachoTBSSDirective() const { return HasMachoTBSSDirective; }
334    bool hasStaticCtorDtorReferenceInStaticMode() const {
335      return HasStaticCtorDtorReferenceInStaticMode;
336    }
337    bool getLinkerRequiresNonEmptyDwarfLines() const {
338      return LinkerRequiresNonEmptyDwarfLines;
339    }
340    unsigned getMaxInstLength() const {
341      return MaxInstLength;
342    }
343    const char *getPCSymbol() const {
344      return PCSymbol;
345    }
346    char getSeparatorChar() const {
347      return SeparatorChar;
348    }
349    unsigned getCommentColumn() const {
350      return CommentColumn;
351    }
352    const char *getCommentString() const {
353      return CommentString;
354    }
355    const char *getLabelSuffix() const {
356      return LabelSuffix;
357    }
358    const char *getGlobalPrefix() const {
359      return GlobalPrefix;
360    }
361    const char *getPrivateGlobalPrefix() const {
362      return PrivateGlobalPrefix;
363    }
364    const char *getLinkerPrivateGlobalPrefix() const {
365      return LinkerPrivateGlobalPrefix;
366    }
367    const char *getInlineAsmStart() const {
368      return InlineAsmStart;
369    }
370    const char *getInlineAsmEnd() const {
371      return InlineAsmEnd;
372    }
373    unsigned getAssemblerDialect() const {
374      return AssemblerDialect;
375    }
376    bool doesAllowQuotesInName() const {
377      return AllowQuotesInName;
378    }
379    bool doesAllowNameToStartWithDigit() const {
380      return AllowNameToStartWithDigit;
381    }
382    bool doesAllowPeriodsInName() const {
383      return AllowPeriodsInName;
384    }
385    const char *getZeroDirective() const {
386      return ZeroDirective;
387    }
388    const char *getAsciiDirective() const {
389      return AsciiDirective;
390    }
391    const char *getAscizDirective() const {
392      return AscizDirective;
393    }
394    const char *getAlignDirective() const {
395      return AlignDirective;
396    }
397    bool getAlignmentIsInBytes() const {
398      return AlignmentIsInBytes;
399    }
400    unsigned getTextAlignFillValue() const {
401      return TextAlignFillValue;
402    }
403    const char *getGlobalDirective() const {
404      return GlobalDirective;
405    }
406    const char *getExternDirective() const {
407      return ExternDirective;
408    }
409    bool hasSetDirective() const { return HasSetDirective; }
410    bool needsSetToChangeDiffSize() const { return NeedsSetToChangeDiffSize; }
411    bool hasLCOMMDirective() const { return HasLCOMMDirective; }
412    bool hasDotTypeDotSizeDirective() const {return HasDotTypeDotSizeDirective;}
413    bool getCOMMDirectiveAlignmentIsInBytes() const {
414      return COMMDirectiveAlignmentIsInBytes;
415    }
416    bool hasSingleParameterDotFile() const { return HasSingleParameterDotFile; }
417    bool hasNoDeadStrip() const { return HasNoDeadStrip; }
418    bool hasSymbolResolver() const { return HasSymbolResolver; }
419    const char *getWeakRefDirective() const { return WeakRefDirective; }
420    const char *getWeakDefDirective() const { return WeakDefDirective; }
421    const char *getLinkOnceDirective() const { return LinkOnceDirective; }
422
423    MCSymbolAttr getHiddenVisibilityAttr() const { return HiddenVisibilityAttr;}
424    MCSymbolAttr getProtectedVisibilityAttr() const {
425      return ProtectedVisibilityAttr;
426    }
427    bool hasLEB128() const {
428      return HasLEB128;
429    }
430    bool doesSupportDebugInformation() const {
431      return SupportsDebugInformation;
432    }
433    bool doesSupportExceptionHandling() const {
434      return ExceptionsType != ExceptionHandling::None;
435    }
436    ExceptionHandling::ExceptionsType getExceptionHandlingType() const {
437      return ExceptionsType;
438    }
439    bool doesDwarfRequireFrameSection() const {
440      return DwarfRequiresFrameSection;
441    }
442    bool doesDwarfUsesInlineInfoSection() const {
443      return DwarfUsesInlineInfoSection;
444    }
445    const char *getDwarfSectionOffsetDirective() const {
446      return DwarfSectionOffsetDirective;
447    }
448    bool doesDwarfUsesAbsoluteLabelForStmtList() const {
449      return DwarfUsesAbsoluteLabelForStmtList;
450    }
451    bool doesDwarfUsesLabelOffsetForRanges() const {
452      return DwarfUsesLabelOffsetForRanges;
453    }
454    const char *const *getAsmCBE() const {
455      return AsmTransCBE;
456    }
457  };
458}
459
460#endif
461