MCAsmInfo.h revision 152a29bfa6fa505182658d046bc75626e10d67c3 
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  /// MCAsmInfo - This class is intended to be used as a base class for asm
24  /// properties and features specific to the target.
25  namespace ExceptionHandling { enum ExceptionsType { None, Dwarf, SjLj }; }
26
27  class MCAsmInfo {
28  protected:
29    //===------------------------------------------------------------------===//
30    // Properties to be set by the target writer, used to configure asm printer.
31    //
32
33    /// NonexecutableStackDirective - Directive for declaring to the
34    /// linker and beyond that the emitted code does not require stack
35    /// memory to be executable.
36    const char *NonexecutableStackDirective; // Default is null.
37
38    /// HasMachoZeroFillDirective - True if this is a MachO target that supports
39    /// the macho-specific .zerofill directive for emitting BSS Symbols.
40    bool HasMachoZeroFillDirective;               // Default is false.
41
42    /// HasStaticCtorDtorReferenceInStaticMode - True if the compiler should
43    /// emit a ".reference .constructors_used" or ".reference .destructors_used"
44    /// directive after the a static ctor/dtor list.  This directive is only
45    /// emitted in Static relocation model.
46    bool HasStaticCtorDtorReferenceInStaticMode;  // Default is false.
47
48    /// NeedsSet - True if target asm treats expressions in data directives
49    /// as linktime-relocatable.  For assembly-time computation, we need to
50    /// use a .set.  Thus:
51    /// .set w, x-y
52    /// .long w
53    /// is computed at assembly time, while
54    /// .long x-y
55    /// is relocated if the relative locations of x and y change at linktime.
56    /// We want both these things in different places.
57    bool NeedsSet;                           // Defaults 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 60
75
76    /// CommentString - This indicates the comment character used by the
77    /// assembler.
78    const char *CommentString;               // Defaults to "#"
79
80    /// GlobalPrefix - If this is set to a non-empty string, it is prepended
81    /// onto all global symbols.  This is often used for "_" or ".".
82    const char *GlobalPrefix;                // Defaults to ""
83
84    /// PrivateGlobalPrefix - This prefix is used for globals like constant
85    /// pool entries that are completely private to the .s file and should not
86    /// have names in the .o file.  This is often "." or "L".
87    const char *PrivateGlobalPrefix;         // Defaults to "."
88
89    /// LinkerPrivateGlobalPrefix - This prefix is used for symbols that should
90    /// be passed through the assembler but be removed by the linker.  This
91    /// is "l" on Darwin, currently used for some ObjC metadata.
92    const char *LinkerPrivateGlobalPrefix;   // Defaults to ""
93
94    /// InlineAsmStart/End - If these are nonempty, they contain a directive to
95    /// emit before and after an inline assembly statement.
96    const char *InlineAsmStart;              // Defaults to "#APP\n"
97    const char *InlineAsmEnd;                // Defaults to "#NO_APP\n"
98
99    /// AssemblerDialect - Which dialect of an assembler variant to use.
100    unsigned AssemblerDialect;               // Defaults to 0
101
102    /// AllowQuotesInName - This is true if the assembler allows for complex
103    /// symbol names to be surrounded in quotes.  This defaults to false.
104    bool AllowQuotesInName;
105
106    /// AllowNameToStartWithDigit - This is true if the assembler allows symbol
107    /// names to start with a digit (e.g., "0x0021").  This defaults to false.
108    bool AllowNameToStartWithDigit;
109
110    //===--- Data Emission Directives -------------------------------------===//
111
112    /// ZeroDirective - this should be set to the directive used to get some
113    /// number of zero bytes emitted to the current section.  Common cases are
114    /// "\t.zero\t" and "\t.space\t".  If this is set to null, the
115    /// Data*bitsDirective's will be used to emit zero bytes.
116    const char *ZeroDirective;               // Defaults to "\t.zero\t"
117
118    /// AsciiDirective - This directive allows emission of an ascii string with
119    /// the standard C escape characters embedded into it.
120    const char *AsciiDirective;              // Defaults to "\t.ascii\t"
121
122    /// AscizDirective - If not null, this allows for special handling of
123    /// zero terminated strings on this target.  This is commonly supported as
124    /// ".asciz".  If a target doesn't support this, it can be set to null.
125    const char *AscizDirective;              // Defaults to "\t.asciz\t"
126
127    /// DataDirectives - These directives are used to output some unit of
128    /// integer data to the current section.  If a data directive is set to
129    /// null, smaller data directives will be used to emit the large sizes.
130    const char *Data8bitsDirective;          // Defaults to "\t.byte\t"
131    const char *Data16bitsDirective;         // Defaults to "\t.short\t"
132    const char *Data32bitsDirective;         // Defaults to "\t.long\t"
133    const char *Data64bitsDirective;         // Defaults to "\t.quad\t"
134
135    /// getDataASDirective - Return the directive that should be used to emit
136    /// data of the specified size to the specified numeric address space.
137    virtual const char *getDataASDirective(unsigned Size, unsigned AS) const {
138      assert(AS != 0 && "Don't know the directives for default addr space");
139      return 0;
140    }
141
142    /// SunStyleELFSectionSwitchSyntax - This is true if this target uses "Sun
143    /// Style" syntax for section switching ("#alloc,#write" etc) instead of the
144    /// normal ELF syntax (,"a,w") in .section directives.
145    bool SunStyleELFSectionSwitchSyntax;     // Defaults to false.
146
147    /// UsesELFSectionDirectiveForBSS - This is true if this target uses ELF
148    /// '.section' directive before the '.bss' one. It's used for PPC/Linux
149    /// which doesn't support the '.bss' directive only.
150    bool UsesELFSectionDirectiveForBSS;      // Defaults to false.
151
152    //===--- Alignment Information ----------------------------------------===//
153
154    /// AlignDirective - The directive used to emit round up to an alignment
155    /// boundary.
156    ///
157    const char *AlignDirective;              // Defaults to "\t.align\t"
158
159    /// AlignmentIsInBytes - If this is true (the default) then the asmprinter
160    /// emits ".align N" directives, where N is the number of bytes to align to.
161    /// Otherwise, it emits ".align log2(N)", e.g. 3 to align to an 8 byte
162    /// boundary.
163    bool AlignmentIsInBytes;                 // Defaults to true
164
165    /// TextAlignFillValue - If non-zero, this is used to fill the executable
166    /// space created as the result of a alignment directive.
167    unsigned TextAlignFillValue;             // Defaults to 0
168
169    //===--- Section Switching Directives ---------------------------------===//
170
171    /// JumpTableDirective - if non-null, the directive to emit before jump
172    /// table entries.  FIXME: REMOVE THIS.
173    const char *JumpTableDirective;          // Defaults to NULL.
174    const char *PICJumpTableDirective;       // Defaults to NULL.
175
176
177    //===--- Global Variable Emission Directives --------------------------===//
178
179    /// GlobalDirective - This is the directive used to declare a global entity.
180    ///
181    const char *GlobalDirective;             // Defaults to NULL.
182
183    /// ExternDirective - This is the directive used to declare external
184    /// globals.
185    ///
186    const char *ExternDirective;             // Defaults to NULL.
187
188    /// SetDirective - This is the name of a directive that can be used to tell
189    /// the assembler to set the value of a variable to some expression.
190    const char *SetDirective;                // Defaults to null.
191
192    /// LCOMMDirective - This is the name of a directive (if supported) that can
193    /// be used to efficiently declare a local (internal) block of zero
194    /// initialized data in the .bss/.data section.  The syntax expected is:
195    /// @verbatim <LCOMMDirective> SYMBOLNAME LENGTHINBYTES
196    /// @endverbatim
197    const char *LCOMMDirective;              // Defaults to null.
198
199    const char *COMMDirective;               // Defaults to "\t.comm\t".
200
201    /// COMMDirectiveTakesAlignment - True if COMMDirective take a third
202    /// argument that specifies the alignment of the declaration.
203    bool COMMDirectiveTakesAlignment;        // Defaults to true.
204
205    /// HasDotTypeDotSizeDirective - True if the target has .type and .size
206    /// directives, this is true for most ELF targets.
207    bool HasDotTypeDotSizeDirective;         // Defaults to true.
208
209    /// HasSingleParameterDotFile - True if the target has a single parameter
210    /// .file directive, this is true for ELF targets.
211    bool HasSingleParameterDotFile;          // Defaults to true.
212
213    /// HasNoDeadStrip - True if this target supports the MachO .no_dead_strip
214    /// directive.
215    bool HasNoDeadStrip;                     // Defaults to false.
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    /// HiddenVisibilityAttr - This attribute, if not MCSA_Invalid, is used to
230    /// declare a symbol as having hidden visibility.
231    MCSymbolAttr HiddenVisibilityAttr;       // Defaults to MCSA_Hidden.
232
233    /// ProtectedVisibilityAttr - This attribute, if not MCSA_Invalid, is used
234    /// to declare a symbol as having protected visibility.
235    MCSymbolAttr ProtectedVisibilityAttr;    // Defaults to MCSA_Protected
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 {return HasDotTypeDotSizeDirective;}
414    bool hasSingleParameterDotFile() const { return HasSingleParameterDotFile; }
415    bool hasNoDeadStrip() const { return HasNoDeadStrip; }
416    const char *getWeakRefDirective() const { return WeakRefDirective; }
417    const char *getWeakDefDirective() const { return WeakDefDirective; }
418    const char *getLinkOnceDirective() const { return LinkOnceDirective; }
419
420    MCSymbolAttr getHiddenVisibilityAttr() const { return HiddenVisibilityAttr;}
421    MCSymbolAttr getProtectedVisibilityAttr() const {
422      return ProtectedVisibilityAttr;
423    }
424    bool isAbsoluteDebugSectionOffsets() const {
425      return AbsoluteDebugSectionOffsets;
426    }
427    bool isAbsoluteEHSectionOffsets() const {
428      return AbsoluteEHSectionOffsets;
429    }
430    bool hasLEB128() const {
431      return HasLEB128;
432    }
433    bool hasDotLocAndDotFile() const {
434      return HasDotLocAndDotFile;
435    }
436    bool doesSupportDebugInformation() const {
437      return SupportsDebugInformation;
438    }
439    bool doesSupportExceptionHandling() const {
440      return ExceptionsType != ExceptionHandling::None;
441    }
442    ExceptionHandling::ExceptionsType getExceptionHandlingType() const {
443      return ExceptionsType;
444    }
445    bool doesDwarfRequireFrameSection() const {
446      return DwarfRequiresFrameSection;
447    }
448    bool doesDwarfUsesInlineInfoSection() const {
449      return DwarfUsesInlineInfoSection;
450    }
451    bool is_EHSymbolPrivate() const {
452      return Is_EHSymbolPrivate;
453    }
454    const char *getGlobalEHDirective() const {
455      return GlobalEHDirective;
456    }
457    bool getSupportsWeakOmittedEHFrame() const {
458      return SupportsWeakOmittedEHFrame;
459    }
460    const char *getDwarfSectionOffsetDirective() const {
461      return DwarfSectionOffsetDirective;
462    }
463    const char *const *getAsmCBE() const {
464      return AsmTransCBE;
465    }
466  };
467}
468
469#endif
470