MCAsmInfo.h revision 8eeba35babf3114966fc4e6e8522057e46b610db 
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 <cassert>
20
21namespace llvm {
22  /// MCAsmInfo - This class is intended to be used as a base class for asm
23  /// properties and features specific to the target.
24  namespace ExceptionHandling { enum ExceptionsType { None, Dwarf, SjLj }; }
25
26  class MCAsmInfo {
27  protected:
28    //===------------------------------------------------------------------===//
29    // Properties to be set by the target writer, used to configure asm printer.
30    //
31
32    /// NonexecutableStackDirective - Directive for declaring to the
33    /// linker and beyond that the emitted code does not require stack
34    /// memory to be executable.
35    const char *NonexecutableStackDirective; // Default is null.
36
37    /// HasMachoZeroFillDirective - True if this is a MachO target that supports
38    /// the macho-specific .zerofill directive for emitting BSS Symbols.
39    bool HasMachoZeroFillDirective;               // Default is false.
40
41    /// HasStaticCtorDtorReferenceInStaticMode - True if the compiler should
42    /// emit a ".reference .constructors_used" or ".reference .destructors_used"
43    /// directive after the a static ctor/dtor list.  This directive is only
44    /// emitted in Static relocation model.
45    bool HasStaticCtorDtorReferenceInStaticMode;  // Default is false.
46
47    /// NeedsSet - True if target asm treats expressions in data directives
48    /// as linktime-relocatable.  For assembly-time computation, we need to
49    /// use a .set.  Thus:
50    /// .set w, x-y
51    /// .long w
52    /// is computed at assembly time, while
53    /// .long x-y
54    /// is relocated if the relative locations of x and y change at linktime.
55    /// We want both these things in different places.
56    bool NeedsSet;                           // Defaults to false.
57
58    /// MaxInstLength - This is the maximum possible length of an instruction,
59    /// which is needed to compute the size of an inline asm.
60    unsigned MaxInstLength;                  // Defaults to 4.
61
62    /// PCSymbol - The symbol used to represent the current PC.  Used in PC
63    /// relative expressions.
64    const char *PCSymbol;                    // Defaults to "$".
65
66    /// SeparatorChar - This character, if specified, is used to separate
67    /// instructions from each other when on the same line.  This is used to
68    /// measure inline asm instructions.
69    char SeparatorChar;                      // Defaults to ';'
70
71    /// CommentColumn - This indicates the comment num (zero-based) at
72    /// which asm comments should be printed.
73    unsigned CommentColumn;                  // Defaults to 60
74
75    /// CommentString - This indicates the comment character used by the
76    /// assembler.
77    const char *CommentString;               // Defaults to "#"
78
79    /// GlobalPrefix - If this is set to a non-empty string, it is prepended
80    /// onto all global symbols.  This is often used for "_" or ".".
81    const char *GlobalPrefix;                // Defaults to ""
82
83    /// PrivateGlobalPrefix - This prefix is used for globals like constant
84    /// pool entries that are completely private to the .s file and should not
85    /// have names in the .o file.  This is often "." or "L".
86    const char *PrivateGlobalPrefix;         // Defaults to "."
87
88    /// LinkerPrivateGlobalPrefix - This prefix is used for symbols that should
89    /// be passed through the assembler but be removed by the linker.  This
90    /// is "l" on Darwin, currently used for some ObjC metadata.
91    const char *LinkerPrivateGlobalPrefix;   // Defaults to ""
92
93    /// InlineAsmStart/End - If these are nonempty, they contain a directive to
94    /// emit before and after an inline assembly statement.
95    const char *InlineAsmStart;              // Defaults to "#APP\n"
96    const char *InlineAsmEnd;                // Defaults to "#NO_APP\n"
97
98    /// AssemblerDialect - Which dialect of an assembler variant to use.
99    unsigned AssemblerDialect;               // Defaults to 0
100
101    /// AllowQuotesInName - This is true if the assembler allows for complex
102    /// symbol names to be surrounded in quotes.  This defaults to false.
103    bool AllowQuotesInName;
104
105    /// AllowNameToStartWithDigit - This is true if the assembler allows symbol
106    /// names to start with a digit (e.g., "0x0021").  This defaults to false.
107    bool AllowNameToStartWithDigit;
108
109    //===--- Data Emission Directives -------------------------------------===//
110
111    /// ZeroDirective - this should be set to the directive used to get some
112    /// number of zero bytes emitted to the current section.  Common cases are
113    /// "\t.zero\t" and "\t.space\t".  If this is set to null, the
114    /// Data*bitsDirective's will be used to emit zero bytes.
115    const char *ZeroDirective;               // Defaults to "\t.zero\t"
116
117    /// AsciiDirective - This directive allows emission of an ascii string with
118    /// the standard C escape characters embedded into it.
119    const char *AsciiDirective;              // Defaults to "\t.ascii\t"
120
121    /// AscizDirective - If not null, this allows for special handling of
122    /// zero terminated strings on this target.  This is commonly supported as
123    /// ".asciz".  If a target doesn't support this, it can be set to null.
124    const char *AscizDirective;              // Defaults to "\t.asciz\t"
125
126    /// DataDirectives - These directives are used to output some unit of
127    /// integer data to the current section.  If a data directive is set to
128    /// null, smaller data directives will be used to emit the large sizes.
129    const char *Data8bitsDirective;          // Defaults to "\t.byte\t"
130    const char *Data16bitsDirective;         // Defaults to "\t.short\t"
131    const char *Data32bitsDirective;         // Defaults to "\t.long\t"
132    const char *Data64bitsDirective;         // Defaults to "\t.quad\t"
133
134    /// getDataASDirective - Return the directive that should be used to emit
135    /// data of the specified size to the specified numeric address space.
136    virtual const char *getDataASDirective(unsigned Size, unsigned AS) const {
137      assert(AS != 0 && "Don't know the directives for default addr space");
138      return 0;
139    }
140
141    /// SunStyleELFSectionSwitchSyntax - This is true if this target uses "Sun
142    /// Style" syntax for section switching ("#alloc,#write" etc) instead of the
143    /// normal ELF syntax (,"a,w") in .section directives.
144    bool SunStyleELFSectionSwitchSyntax;     // Defaults to false.
145
146    /// UsesELFSectionDirectiveForBSS - This is true if this target uses ELF
147    /// '.section' directive before the '.bss' one. It's used for PPC/Linux
148    /// which doesn't support the '.bss' directive only.
149    bool UsesELFSectionDirectiveForBSS;      // Defaults to false.
150
151    //===--- Alignment Information ----------------------------------------===//
152
153    /// AlignDirective - The directive used to emit round up to an alignment
154    /// boundary.
155    ///
156    const char *AlignDirective;              // Defaults to "\t.align\t"
157
158    /// AlignmentIsInBytes - If this is true (the default) then the asmprinter
159    /// emits ".align N" directives, where N is the number of bytes to align to.
160    /// Otherwise, it emits ".align log2(N)", e.g. 3 to align to an 8 byte
161    /// boundary.
162    bool AlignmentIsInBytes;                 // Defaults to true
163
164    /// TextAlignFillValue - If non-zero, this is used to fill the executable
165    /// space created as the result of a alignment directive.
166    unsigned TextAlignFillValue;             // Defaults to 0
167
168    //===--- Section Switching Directives ---------------------------------===//
169
170    /// JumpTableDirective - if non-null, the directive to emit before jump
171    /// table entries.  FIXME: REMOVE THIS.
172    const char *JumpTableDirective;          // Defaults to NULL.
173    const char *PICJumpTableDirective;       // Defaults to NULL.
174
175
176    //===--- Global Variable Emission Directives --------------------------===//
177
178    /// GlobalDirective - This is the directive used to declare a global entity.
179    ///
180    const char *GlobalDirective;             // Defaults to NULL.
181
182    /// ExternDirective - This is the directive used to declare external
183    /// globals.
184    ///
185    const char *ExternDirective;             // Defaults to NULL.
186
187    /// SetDirective - This is the name of a directive that can be used to tell
188    /// the assembler to set the value of a variable to some expression.
189    const char *SetDirective;                // Defaults to null.
190
191    /// LCOMMDirective - This is the name of a directive (if supported) that can
192    /// be used to efficiently declare a local (internal) block of zero
193    /// initialized data in the .bss/.data section.  The syntax expected is:
194    /// @verbatim <LCOMMDirective> SYMBOLNAME LENGTHINBYTES
195    /// @endverbatim
196    const char *LCOMMDirective;              // Defaults to null.
197
198    const char *COMMDirective;               // Defaults to "\t.comm\t".
199
200    /// COMMDirectiveTakesAlignment - True if COMMDirective take a third
201    /// argument that specifies the alignment of the declaration.
202    bool COMMDirectiveTakesAlignment;        // Defaults to true.
203
204    /// HasDotTypeDotSizeDirective - True if the target has .type and .size
205    /// directives, this is true for most ELF targets.
206    bool HasDotTypeDotSizeDirective;         // Defaults to true.
207
208    /// HasSingleParameterDotFile - True if the target has a single parameter
209    /// .file directive, this is true for ELF targets.
210    bool HasSingleParameterDotFile;          // Defaults to true.
211
212    /// UsedDirective - This directive, if non-null, is used to declare a global
213    /// as being used somehow that the assembler can't see.  This prevents dead
214    /// code elimination on some targets.
215    const char *UsedDirective;               // Defaults to NULL.
216
217    /// WeakRefDirective - This directive, if non-null, is used to declare a
218    /// global as being a weak undefined symbol.
219    const char *WeakRefDirective;            // Defaults to NULL.
220
221    /// WeakDefDirective - This directive, if non-null, is used to declare a
222    /// global as being a weak defined symbol.
223    const char *WeakDefDirective;            // Defaults to NULL.
224
225    /// LinkOnceDirective - This directive, if non-null is used to declare a
226    /// global as being a weak defined symbol.  This is used on cygwin/mingw.
227    const char *LinkOnceDirective;           // Defaults to NULL.
228
229    /// HiddenDirective - This directive, if non-null, is used to declare a
230    /// global or function as having hidden visibility.
231    const char *HiddenDirective;             // Defaults to "\t.hidden\t".
232
233    /// ProtectedDirective - This directive, if non-null, is used to declare a
234    /// global or function as having protected visibility.
235    const char *ProtectedDirective;          // Defaults to "\t.protected\t".
236
237    //===--- Dwarf Emission Directives -----------------------------------===//
238
239    /// AbsoluteDebugSectionOffsets - True if we should emit abolute section
240    /// offsets for debug information.
241    bool AbsoluteDebugSectionOffsets;        // Defaults to false.
242
243    /// AbsoluteEHSectionOffsets - True if we should emit abolute section
244    /// offsets for EH information. Defaults to false.
245    bool AbsoluteEHSectionOffsets;
246
247    /// HasLEB128 - True if target asm supports leb128 directives.
248    bool HasLEB128;                          // Defaults to false.
249
250    /// hasDotLocAndDotFile - True if target asm supports .loc and .file
251    /// directives for emitting debugging information.
252    bool HasDotLocAndDotFile;                // Defaults to false.
253
254    /// SupportsDebugInformation - True if target supports emission of debugging
255    /// information.
256    bool SupportsDebugInformation;           // Defaults to false.
257
258    /// SupportsExceptionHandling - True if target supports exception handling.
259    ExceptionHandling::ExceptionsType ExceptionsType; // Defaults to None
260
261    /// RequiresFrameSection - true if the Dwarf2 output needs a frame section
262    bool DwarfRequiresFrameSection;          // Defaults to true.
263
264    /// DwarfUsesInlineInfoSection - True if DwarfDebugInlineSection is used to
265    /// encode inline subroutine information.
266    bool DwarfUsesInlineInfoSection;         // Defaults to false.
267
268    /// Is_EHSymbolPrivate - If set, the "_foo.eh" is made private so that it
269    /// doesn't show up in the symbol table of the object file.
270    bool Is_EHSymbolPrivate;                 // Defaults to true.
271
272    /// GlobalEHDirective - This is the directive used to make exception frame
273    /// tables globally visible.
274    const char *GlobalEHDirective;           // Defaults to NULL.
275
276    /// SupportsWeakEmptyEHFrame - True if target assembler and linker will
277    /// handle a weak_definition of constant 0 for an omitted EH frame.
278    bool SupportsWeakOmittedEHFrame;         // Defaults to true.
279
280    /// DwarfSectionOffsetDirective - Special section offset directive.
281    const char* DwarfSectionOffsetDirective; // Defaults to NULL
282
283    //===--- CBE Asm Translation Table -----------------------------------===//
284
285    const char *const *AsmTransCBE;          // Defaults to empty
286
287  public:
288    explicit MCAsmInfo();
289    virtual ~MCAsmInfo();
290
291    /// getSLEB128Size - Compute the number of bytes required for a signed
292    /// leb128 value.
293    static unsigned getSLEB128Size(int Value);
294
295    /// getULEB128Size - Compute the number of bytes required for an unsigned
296    /// leb128 value.
297    static unsigned getULEB128Size(unsigned Value);
298
299    // Data directive accessors.
300    //
301    const char *getData8bitsDirective(unsigned AS = 0) const {
302      return AS == 0 ? Data8bitsDirective : getDataASDirective(8, AS);
303    }
304    const char *getData16bitsDirective(unsigned AS = 0) const {
305      return AS == 0 ? Data16bitsDirective : getDataASDirective(16, AS);
306    }
307    const char *getData32bitsDirective(unsigned AS = 0) const {
308      return AS == 0 ? Data32bitsDirective : getDataASDirective(32, AS);
309    }
310    const char *getData64bitsDirective(unsigned AS = 0) const {
311      return AS == 0 ? Data64bitsDirective : getDataASDirective(64, AS);
312    }
313
314
315    bool usesSunStyleELFSectionSwitchSyntax() const {
316      return SunStyleELFSectionSwitchSyntax;
317    }
318
319    bool usesELFSectionDirectiveForBSS() const {
320      return UsesELFSectionDirectiveForBSS;
321    }
322
323    // Accessors.
324    //
325    bool hasMachoZeroFillDirective() const { return HasMachoZeroFillDirective; }
326    bool hasStaticCtorDtorReferenceInStaticMode() const {
327      return HasStaticCtorDtorReferenceInStaticMode;
328    }
329    const char *getNonexecutableStackDirective() const {
330      return NonexecutableStackDirective;
331    }
332    bool needsSet() const {
333      return NeedsSet;
334    }
335    unsigned getMaxInstLength() const {
336      return MaxInstLength;
337    }
338    const char *getPCSymbol() const {
339      return PCSymbol;
340    }
341    char getSeparatorChar() const {
342      return SeparatorChar;
343    }
344    unsigned getCommentColumn() const {
345      return CommentColumn;
346    }
347    const char *getCommentString() const {
348      return CommentString;
349    }
350    const char *getGlobalPrefix() const {
351      return GlobalPrefix;
352    }
353    const char *getPrivateGlobalPrefix() const {
354      return PrivateGlobalPrefix;
355    }
356    const char *getLinkerPrivateGlobalPrefix() const {
357      return LinkerPrivateGlobalPrefix;
358    }
359    const char *getInlineAsmStart() const {
360      return InlineAsmStart;
361    }
362    const char *getInlineAsmEnd() const {
363      return InlineAsmEnd;
364    }
365    unsigned getAssemblerDialect() const {
366      return AssemblerDialect;
367    }
368    bool doesAllowQuotesInName() const {
369      return AllowQuotesInName;
370    }
371    bool doesAllowNameToStartWithDigit() const {
372      return AllowNameToStartWithDigit;
373    }
374    const char *getZeroDirective() const {
375      return ZeroDirective;
376    }
377    const char *getAsciiDirective() const {
378      return AsciiDirective;
379    }
380    const char *getAscizDirective() const {
381      return AscizDirective;
382    }
383    const char *getJumpTableDirective(bool isPIC) const {
384      return isPIC ? PICJumpTableDirective : JumpTableDirective;
385    }
386    const char *getAlignDirective() const {
387      return AlignDirective;
388    }
389    bool getAlignmentIsInBytes() const {
390      return AlignmentIsInBytes;
391    }
392    unsigned getTextAlignFillValue() const {
393      return TextAlignFillValue;
394    }
395    const char *getGlobalDirective() const {
396      return GlobalDirective;
397    }
398    const char *getExternDirective() const {
399      return ExternDirective;
400    }
401    const char *getSetDirective() const {
402      return SetDirective;
403    }
404    const char *getLCOMMDirective() const {
405      return LCOMMDirective;
406    }
407    const char *getCOMMDirective() const {
408      return COMMDirective;
409    }
410    bool getCOMMDirectiveTakesAlignment() const {
411      return COMMDirectiveTakesAlignment;
412    }
413    bool hasDotTypeDotSizeDirective() const {
414      return HasDotTypeDotSizeDirective;
415    }
416    bool hasSingleParameterDotFile() const {
417      return HasSingleParameterDotFile;
418    }
419    const char *getUsedDirective() const {
420      return UsedDirective;
421    }
422    const char *getWeakRefDirective() const { return WeakRefDirective; }
423    const char *getWeakDefDirective() const { return WeakDefDirective; }
424    const char *getLinkOnceDirective() const { return LinkOnceDirective; }
425    const char *getHiddenDirective() const {
426      return HiddenDirective;
427    }
428    const char *getProtectedDirective() const {
429      return ProtectedDirective;
430    }
431    bool isAbsoluteDebugSectionOffsets() const {
432      return AbsoluteDebugSectionOffsets;
433    }
434    bool isAbsoluteEHSectionOffsets() const {
435      return AbsoluteEHSectionOffsets;
436    }
437    bool hasLEB128() const {
438      return HasLEB128;
439    }
440    bool hasDotLocAndDotFile() const {
441      return HasDotLocAndDotFile;
442    }
443    bool doesSupportDebugInformation() const {
444      return SupportsDebugInformation;
445    }
446    bool doesSupportExceptionHandling() const {
447      return ExceptionsType != ExceptionHandling::None;
448    }
449    ExceptionHandling::ExceptionsType getExceptionHandlingType() const {
450      return ExceptionsType;
451    }
452    bool doesDwarfRequireFrameSection() const {
453      return DwarfRequiresFrameSection;
454    }
455    bool doesDwarfUsesInlineInfoSection() const {
456      return DwarfUsesInlineInfoSection;
457    }
458    bool is_EHSymbolPrivate() const {
459      return Is_EHSymbolPrivate;
460    }
461    const char *getGlobalEHDirective() const {
462      return GlobalEHDirective;
463    }
464    bool getSupportsWeakOmittedEHFrame() const {
465      return SupportsWeakOmittedEHFrame;
466    }
467    const char *getDwarfSectionOffsetDirective() const {
468      return DwarfSectionOffsetDirective;
469    }
470    const char *const *getAsmCBE() const {
471      return AsmTransCBE;
472    }
473  };
474}
475
476#endif
477