MCAsmInfo.h revision 6a315c358ca35625ffd50fdc74556acb26ec7396 
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    /// HasStaticCtorDtorReferenceInStaticMode - True if the compiler should
45    /// emit a ".reference .constructors_used" or ".reference .destructors_used"
46    /// directive after the a static ctor/dtor list.  This directive is only
47    /// emitted in Static relocation model.
48    bool HasStaticCtorDtorReferenceInStaticMode;  // Default is false.
49
50    /// MaxInstLength - This is the maximum possible length of an instruction,
51    /// which is needed to compute the size of an inline asm.
52    unsigned MaxInstLength;                  // Defaults to 4.
53
54    /// PCSymbol - The symbol used to represent the current PC.  Used in PC
55    /// relative expressions.
56    const char *PCSymbol;                    // Defaults to "$".
57
58    /// SeparatorChar - This character, if specified, is used to separate
59    /// instructions from each other when on the same line.  This is used to
60    /// measure inline asm instructions.
61    char SeparatorChar;                      // Defaults to ';'
62
63    /// CommentColumn - This indicates the comment num (zero-based) at
64    /// which asm comments should be printed.
65    unsigned CommentColumn;                  // Defaults to 60
66
67    /// CommentString - This indicates the comment character used by the
68    /// assembler.
69    const char *CommentString;               // Defaults to "#"
70
71    /// GlobalPrefix - If this is set to a non-empty string, it is prepended
72    /// onto all global symbols.  This is often used for "_" or ".".
73    const char *GlobalPrefix;                // Defaults to ""
74
75    /// PrivateGlobalPrefix - This prefix is used for globals like constant
76    /// pool entries that are completely private to the .s file and should not
77    /// have names in the .o file.  This is often "." or "L".
78    const char *PrivateGlobalPrefix;         // Defaults to "."
79
80    /// LinkerPrivateGlobalPrefix - This prefix is used for symbols that should
81    /// be passed through the assembler but be removed by the linker.  This
82    /// is "l" on Darwin, currently used for some ObjC metadata.
83    const char *LinkerPrivateGlobalPrefix;   // Defaults to ""
84
85    /// InlineAsmStart/End - If these are nonempty, they contain a directive to
86    /// emit before and after an inline assembly statement.
87    const char *InlineAsmStart;              // Defaults to "#APP\n"
88    const char *InlineAsmEnd;                // Defaults to "#NO_APP\n"
89
90    /// AssemblerDialect - Which dialect of an assembler variant to use.
91    unsigned AssemblerDialect;               // Defaults to 0
92
93    /// AllowQuotesInName - This is true if the assembler allows for complex
94    /// symbol names to be surrounded in quotes.  This defaults to false.
95    bool AllowQuotesInName;
96
97    /// AllowNameToStartWithDigit - This is true if the assembler allows symbol
98    /// names to start with a digit (e.g., "0x0021").  This defaults to false.
99    bool AllowNameToStartWithDigit;
100
101    //===--- Data Emission Directives -------------------------------------===//
102
103    /// ZeroDirective - this should be set to the directive used to get some
104    /// number of zero bytes emitted to the current section.  Common cases are
105    /// "\t.zero\t" and "\t.space\t".  If this is set to null, the
106    /// Data*bitsDirective's will be used to emit zero bytes.
107    const char *ZeroDirective;               // Defaults to "\t.zero\t"
108
109    /// AsciiDirective - This directive allows emission of an ascii string with
110    /// the standard C escape characters embedded into it.
111    const char *AsciiDirective;              // Defaults to "\t.ascii\t"
112
113    /// AscizDirective - If not null, this allows for special handling of
114    /// zero terminated strings on this target.  This is commonly supported as
115    /// ".asciz".  If a target doesn't support this, it can be set to null.
116    const char *AscizDirective;              // Defaults to "\t.asciz\t"
117
118    /// DataDirectives - These directives are used to output some unit of
119    /// integer data to the current section.  If a data directive is set to
120    /// null, smaller data directives will be used to emit the large sizes.
121    const char *Data8bitsDirective;          // Defaults to "\t.byte\t"
122    const char *Data16bitsDirective;         // Defaults to "\t.short\t"
123    const char *Data32bitsDirective;         // Defaults to "\t.long\t"
124    const char *Data64bitsDirective;         // Defaults to "\t.quad\t"
125
126    /// GPRel32Directive - if non-null, a directive that is used to emit a word
127    /// which should be relocated as a 32-bit GP-relative offset, e.g. .gpword
128    /// on Mips or .gprel32 on Alpha.
129    const char *GPRel32Directive;            // Defaults to NULL.
130
131    /// getDataASDirective - Return the directive that should be used to emit
132    /// data of the specified size to the specified numeric address space.
133    virtual const char *getDataASDirective(unsigned Size, unsigned AS) const {
134      assert(AS != 0 && "Don't know the directives for default addr space");
135      return 0;
136    }
137
138    /// SunStyleELFSectionSwitchSyntax - This is true if this target uses "Sun
139    /// Style" syntax for section switching ("#alloc,#write" etc) instead of the
140    /// normal ELF syntax (,"a,w") in .section directives.
141    bool SunStyleELFSectionSwitchSyntax;     // Defaults to false.
142
143    /// UsesELFSectionDirectiveForBSS - This is true if this target uses ELF
144    /// '.section' directive before the '.bss' one. It's used for PPC/Linux
145    /// which doesn't support the '.bss' directive only.
146    bool UsesELFSectionDirectiveForBSS;      // Defaults to false.
147
148    //===--- Alignment Information ----------------------------------------===//
149
150    /// AlignDirective - The directive used to emit round up to an alignment
151    /// boundary.
152    ///
153    const char *AlignDirective;              // Defaults to "\t.align\t"
154
155    /// AlignmentIsInBytes - If this is true (the default) then the asmprinter
156    /// emits ".align N" directives, where N is the number of bytes to align to.
157    /// Otherwise, it emits ".align log2(N)", e.g. 3 to align to an 8 byte
158    /// boundary.
159    bool AlignmentIsInBytes;                 // Defaults to true
160
161    /// TextAlignFillValue - If non-zero, this is used to fill the executable
162    /// space created as the result of a alignment directive.
163    unsigned TextAlignFillValue;             // Defaults to 0
164
165    //===--- Global Variable Emission Directives --------------------------===//
166
167    /// GlobalDirective - This is the directive used to declare a global entity.
168    ///
169    const char *GlobalDirective;             // Defaults to NULL.
170
171    /// ExternDirective - This is the directive used to declare external
172    /// globals.
173    ///
174    const char *ExternDirective;             // Defaults to NULL.
175
176    /// SetDirective - This is the name of a directive that can be used to tell
177    /// the assembler to set the value of a variable to some expression.
178    const char *SetDirective;                // Defaults to null.
179
180    /// HasLCOMMDirective - This is true if the target supports the .lcomm
181    /// directive.
182    bool HasLCOMMDirective;              // Defaults to false.
183
184    /// HasDotTypeDotSizeDirective - True if the target has .type and .size
185    /// directives, this is true for most ELF targets.
186    bool HasDotTypeDotSizeDirective;         // Defaults to true.
187
188    /// HasSingleParameterDotFile - True if the target has a single parameter
189    /// .file directive, this is true for ELF targets.
190    bool HasSingleParameterDotFile;          // Defaults to true.
191
192    /// HasNoDeadStrip - True if this target supports the MachO .no_dead_strip
193    /// directive.
194    bool HasNoDeadStrip;                     // Defaults to false.
195
196    /// WeakRefDirective - This directive, if non-null, is used to declare a
197    /// global as being a weak undefined symbol.
198    const char *WeakRefDirective;            // Defaults to NULL.
199
200    /// WeakDefDirective - This directive, if non-null, is used to declare a
201    /// global as being a weak defined symbol.
202    const char *WeakDefDirective;            // Defaults to NULL.
203
204    /// LinkOnceDirective - This directive, if non-null is used to declare a
205    /// global as being a weak defined symbol.  This is used on cygwin/mingw.
206    const char *LinkOnceDirective;           // Defaults to NULL.
207
208    /// HiddenVisibilityAttr - This attribute, if not MCSA_Invalid, is used to
209    /// declare a symbol as having hidden visibility.
210    MCSymbolAttr HiddenVisibilityAttr;       // Defaults to MCSA_Hidden.
211
212    /// ProtectedVisibilityAttr - This attribute, if not MCSA_Invalid, is used
213    /// to declare a symbol as having protected visibility.
214    MCSymbolAttr ProtectedVisibilityAttr;    // Defaults to MCSA_Protected
215
216    //===--- Dwarf Emission Directives -----------------------------------===//
217
218    /// AbsoluteDebugSectionOffsets - True if we should emit abolute section
219    /// offsets for debug information.
220    bool AbsoluteDebugSectionOffsets;        // Defaults to false.
221
222    /// AbsoluteEHSectionOffsets - True if we should emit abolute section
223    /// offsets for EH information. Defaults to false.
224    bool AbsoluteEHSectionOffsets;
225
226    /// HasLEB128 - True if target asm supports leb128 directives.
227    bool HasLEB128;                          // Defaults to false.
228
229    /// hasDotLocAndDotFile - True if target asm supports .loc and .file
230    /// directives for emitting debugging information.
231    bool HasDotLocAndDotFile;                // Defaults to false.
232
233    /// SupportsDebugInformation - True if target supports emission of debugging
234    /// information.
235    bool SupportsDebugInformation;           // Defaults to false.
236
237    /// SupportsExceptionHandling - True if target supports exception handling.
238    ExceptionHandling::ExceptionsType ExceptionsType; // Defaults to None
239
240    /// RequiresFrameSection - true if the Dwarf2 output needs a frame section
241    bool DwarfRequiresFrameSection;          // Defaults to true.
242
243    /// DwarfUsesInlineInfoSection - True if DwarfDebugInlineSection is used to
244    /// encode inline subroutine information.
245    bool DwarfUsesInlineInfoSection;         // Defaults to false.
246
247    /// Is_EHSymbolPrivate - If set, the "_foo.eh" is made private so that it
248    /// doesn't show up in the symbol table of the object file.
249    bool Is_EHSymbolPrivate;                 // Defaults to true.
250
251    /// GlobalEHDirective - This is the directive used to make exception frame
252    /// tables globally visible.
253    const char *GlobalEHDirective;           // Defaults to NULL.
254
255    /// SupportsWeakEmptyEHFrame - True if target assembler and linker will
256    /// handle a weak_definition of constant 0 for an omitted EH frame.
257    bool SupportsWeakOmittedEHFrame;         // Defaults to true.
258
259    /// DwarfSectionOffsetDirective - Special section offset directive.
260    const char* DwarfSectionOffsetDirective; // Defaults to NULL
261
262    //===--- CBE Asm Translation Table -----------------------------------===//
263
264    const char *const *AsmTransCBE;          // Defaults to empty
265
266  public:
267    explicit MCAsmInfo();
268    virtual ~MCAsmInfo();
269
270    // FIXME: move these methods to DwarfPrinter when the JIT stops using them.
271    static unsigned getSLEB128Size(int Value);
272    static unsigned getULEB128Size(unsigned Value);
273
274    bool hasSubsectionsViaSymbols() const { return HasSubsectionsViaSymbols; }
275
276    // Data directive accessors.
277    //
278    const char *getData8bitsDirective(unsigned AS = 0) const {
279      return AS == 0 ? Data8bitsDirective : getDataASDirective(8, AS);
280    }
281    const char *getData16bitsDirective(unsigned AS = 0) const {
282      return AS == 0 ? Data16bitsDirective : getDataASDirective(16, AS);
283    }
284    const char *getData32bitsDirective(unsigned AS = 0) const {
285      return AS == 0 ? Data32bitsDirective : getDataASDirective(32, AS);
286    }
287    const char *getData64bitsDirective(unsigned AS = 0) const {
288      return AS == 0 ? Data64bitsDirective : getDataASDirective(64, AS);
289    }
290    const char *getGPRel32Directive() const { return GPRel32Directive; }
291
292    /// getNonexecutableStackSection - Targets can implement this method to
293    /// specify a section to switch to if the translation unit doesn't have any
294    /// trampolines that require an executable stack.
295    virtual MCSection *getNonexecutableStackSection(MCContext &Ctx) const {
296      return 0;
297    }
298
299    bool usesSunStyleELFSectionSwitchSyntax() const {
300      return SunStyleELFSectionSwitchSyntax;
301    }
302
303    bool usesELFSectionDirectiveForBSS() const {
304      return UsesELFSectionDirectiveForBSS;
305    }
306
307    // Accessors.
308    //
309    bool hasMachoZeroFillDirective() const { return HasMachoZeroFillDirective; }
310    bool hasStaticCtorDtorReferenceInStaticMode() const {
311      return HasStaticCtorDtorReferenceInStaticMode;
312    }
313    unsigned getMaxInstLength() const {
314      return MaxInstLength;
315    }
316    const char *getPCSymbol() const {
317      return PCSymbol;
318    }
319    char getSeparatorChar() const {
320      return SeparatorChar;
321    }
322    unsigned getCommentColumn() const {
323      return CommentColumn;
324    }
325    const char *getCommentString() const {
326      return CommentString;
327    }
328    const char *getGlobalPrefix() const {
329      return GlobalPrefix;
330    }
331    const char *getPrivateGlobalPrefix() const {
332      return PrivateGlobalPrefix;
333    }
334    const char *getLinkerPrivateGlobalPrefix() const {
335      return LinkerPrivateGlobalPrefix;
336    }
337    const char *getInlineAsmStart() const {
338      return InlineAsmStart;
339    }
340    const char *getInlineAsmEnd() const {
341      return InlineAsmEnd;
342    }
343    unsigned getAssemblerDialect() const {
344      return AssemblerDialect;
345    }
346    bool doesAllowQuotesInName() const {
347      return AllowQuotesInName;
348    }
349    bool doesAllowNameToStartWithDigit() const {
350      return AllowNameToStartWithDigit;
351    }
352    const char *getZeroDirective() const {
353      return ZeroDirective;
354    }
355    const char *getAsciiDirective() const {
356      return AsciiDirective;
357    }
358    const char *getAscizDirective() const {
359      return AscizDirective;
360    }
361    const char *getAlignDirective() const {
362      return AlignDirective;
363    }
364    bool getAlignmentIsInBytes() const {
365      return AlignmentIsInBytes;
366    }
367    unsigned getTextAlignFillValue() const {
368      return TextAlignFillValue;
369    }
370    const char *getGlobalDirective() const {
371      return GlobalDirective;
372    }
373    const char *getExternDirective() const {
374      return ExternDirective;
375    }
376    const char *getSetDirective() const {
377      return SetDirective;
378    }
379    bool hasLCOMMDirective() const { return HasLCOMMDirective; }
380    bool hasDotTypeDotSizeDirective() const {return HasDotTypeDotSizeDirective;}
381    bool hasSingleParameterDotFile() const { return HasSingleParameterDotFile; }
382    bool hasNoDeadStrip() const { return HasNoDeadStrip; }
383    const char *getWeakRefDirective() const { return WeakRefDirective; }
384    const char *getWeakDefDirective() const { return WeakDefDirective; }
385    const char *getLinkOnceDirective() const { return LinkOnceDirective; }
386
387    MCSymbolAttr getHiddenVisibilityAttr() const { return HiddenVisibilityAttr;}
388    MCSymbolAttr getProtectedVisibilityAttr() const {
389      return ProtectedVisibilityAttr;
390    }
391    bool isAbsoluteDebugSectionOffsets() const {
392      return AbsoluteDebugSectionOffsets;
393    }
394    bool isAbsoluteEHSectionOffsets() const {
395      return AbsoluteEHSectionOffsets;
396    }
397    bool hasLEB128() const {
398      return HasLEB128;
399    }
400    bool hasDotLocAndDotFile() const {
401      return HasDotLocAndDotFile;
402    }
403    bool doesSupportDebugInformation() const {
404      return SupportsDebugInformation;
405    }
406    bool doesSupportExceptionHandling() const {
407      return ExceptionsType != ExceptionHandling::None;
408    }
409    ExceptionHandling::ExceptionsType getExceptionHandlingType() const {
410      return ExceptionsType;
411    }
412    bool doesDwarfRequireFrameSection() const {
413      return DwarfRequiresFrameSection;
414    }
415    bool doesDwarfUsesInlineInfoSection() const {
416      return DwarfUsesInlineInfoSection;
417    }
418    bool is_EHSymbolPrivate() const {
419      return Is_EHSymbolPrivate;
420    }
421    const char *getGlobalEHDirective() const {
422      return GlobalEHDirective;
423    }
424    bool getSupportsWeakOmittedEHFrame() const {
425      return SupportsWeakOmittedEHFrame;
426    }
427    const char *getDwarfSectionOffsetDirective() const {
428      return DwarfSectionOffsetDirective;
429    }
430    const char *const *getAsmCBE() const {
431      return AsmTransCBE;
432    }
433  };
434}
435
436#endif
437