MCAsmInfo.h revision 78f485afb723121eedf4b6907ae6eb53da8af03c 
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    /// NeedsSet - True if target asm treats expressions in data directives
51    /// as linktime-relocatable.  For assembly-time computation, we need to
52    /// use a .set.  Thus:
53    /// .set w, x-y
54    /// .long w
55    /// is computed at assembly time, while
56    /// .long x-y
57    /// is relocated if the relative locations of x and y change at linktime.
58    /// We want both these things in different places.
59    bool NeedsSet;                           // Defaults to false.
60
61    /// MaxInstLength - This is the maximum possible length of an instruction,
62    /// which is needed to compute the size of an inline asm.
63    unsigned MaxInstLength;                  // Defaults to 4.
64
65    /// PCSymbol - The symbol used to represent the current PC.  Used in PC
66    /// relative expressions.
67    const char *PCSymbol;                    // Defaults to "$".
68
69    /// SeparatorChar - This character, if specified, is used to separate
70    /// instructions from each other when on the same line.  This is used to
71    /// measure inline asm instructions.
72    char SeparatorChar;                      // Defaults to ';'
73
74    /// CommentColumn - This indicates the comment num (zero-based) at
75    /// which asm comments should be printed.
76    unsigned CommentColumn;                  // Defaults to 60
77
78    /// CommentString - This indicates the comment character used by the
79    /// assembler.
80    const char *CommentString;               // Defaults to "#"
81
82    /// GlobalPrefix - If this is set to a non-empty string, it is prepended
83    /// onto all global symbols.  This is often used for "_" or ".".
84    const char *GlobalPrefix;                // Defaults to ""
85
86    /// PrivateGlobalPrefix - This prefix is used for globals like constant
87    /// pool entries that are completely private to the .s file and should not
88    /// have names in the .o file.  This is often "." or "L".
89    const char *PrivateGlobalPrefix;         // Defaults to "."
90
91    /// LinkerPrivateGlobalPrefix - This prefix is used for symbols that should
92    /// be passed through the assembler but be removed by the linker.  This
93    /// is "l" on Darwin, currently used for some ObjC metadata.
94    const char *LinkerPrivateGlobalPrefix;   // Defaults to ""
95
96    /// InlineAsmStart/End - If these are nonempty, they contain a directive to
97    /// emit before and after an inline assembly statement.
98    const char *InlineAsmStart;              // Defaults to "#APP\n"
99    const char *InlineAsmEnd;                // Defaults to "#NO_APP\n"
100
101    /// AssemblerDialect - Which dialect of an assembler variant to use.
102    unsigned AssemblerDialect;               // Defaults to 0
103
104    /// AllowQuotesInName - This is true if the assembler allows for complex
105    /// symbol names to be surrounded in quotes.  This defaults to false.
106    bool AllowQuotesInName;
107
108    /// AllowNameToStartWithDigit - This is true if the assembler allows symbol
109    /// names to start with a digit (e.g., "0x0021").  This defaults to false.
110    bool AllowNameToStartWithDigit;
111
112    //===--- Data Emission Directives -------------------------------------===//
113
114    /// ZeroDirective - this should be set to the directive used to get some
115    /// number of zero bytes emitted to the current section.  Common cases are
116    /// "\t.zero\t" and "\t.space\t".  If this is set to null, the
117    /// Data*bitsDirective's will be used to emit zero bytes.
118    const char *ZeroDirective;               // Defaults to "\t.zero\t"
119
120    /// AsciiDirective - This directive allows emission of an ascii string with
121    /// the standard C escape characters embedded into it.
122    const char *AsciiDirective;              // Defaults to "\t.ascii\t"
123
124    /// AscizDirective - If not null, this allows for special handling of
125    /// zero terminated strings on this target.  This is commonly supported as
126    /// ".asciz".  If a target doesn't support this, it can be set to null.
127    const char *AscizDirective;              // Defaults to "\t.asciz\t"
128
129    /// DataDirectives - These directives are used to output some unit of
130    /// integer data to the current section.  If a data directive is set to
131    /// null, smaller data directives will be used to emit the large sizes.
132    const char *Data8bitsDirective;          // Defaults to "\t.byte\t"
133    const char *Data16bitsDirective;         // Defaults to "\t.short\t"
134    const char *Data32bitsDirective;         // Defaults to "\t.long\t"
135    const char *Data64bitsDirective;         // Defaults to "\t.quad\t"
136
137    /// GPRel32Directive - if non-null, a directive that is used to emit a word
138    /// which should be relocated as a 32-bit GP-relative offset, e.g. .gpword
139    /// on Mips or .gprel32 on Alpha.
140    const char *GPRel32Directive;            // Defaults to NULL.
141
142    /// getDataASDirective - Return the directive that should be used to emit
143    /// data of the specified size to the specified numeric address space.
144    virtual const char *getDataASDirective(unsigned Size, unsigned AS) const {
145      assert(AS != 0 && "Don't know the directives for default addr space");
146      return 0;
147    }
148
149    /// SunStyleELFSectionSwitchSyntax - This is true if this target uses "Sun
150    /// Style" syntax for section switching ("#alloc,#write" etc) instead of the
151    /// normal ELF syntax (,"a,w") in .section directives.
152    bool SunStyleELFSectionSwitchSyntax;     // Defaults to false.
153
154    /// UsesELFSectionDirectiveForBSS - This is true if this target uses ELF
155    /// '.section' directive before the '.bss' one. It's used for PPC/Linux
156    /// which doesn't support the '.bss' directive only.
157    bool UsesELFSectionDirectiveForBSS;      // Defaults to false.
158
159    //===--- Alignment Information ----------------------------------------===//
160
161    /// AlignDirective - The directive used to emit round up to an alignment
162    /// boundary.
163    ///
164    const char *AlignDirective;              // Defaults to "\t.align\t"
165
166    /// AlignmentIsInBytes - If this is true (the default) then the asmprinter
167    /// emits ".align N" directives, where N is the number of bytes to align to.
168    /// Otherwise, it emits ".align log2(N)", e.g. 3 to align to an 8 byte
169    /// boundary.
170    bool AlignmentIsInBytes;                 // Defaults to true
171
172    /// TextAlignFillValue - If non-zero, this is used to fill the executable
173    /// space created as the result of a alignment directive.
174    unsigned TextAlignFillValue;             // Defaults to 0
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    /// HasLCOMMDirective - This is true if the target supports the .lcomm
192    /// directive.
193    bool HasLCOMMDirective;              // Defaults to false.
194
195    /// HasDotTypeDotSizeDirective - True if the target has .type and .size
196    /// directives, this is true for most ELF targets.
197    bool HasDotTypeDotSizeDirective;         // Defaults to true.
198
199    /// HasSingleParameterDotFile - True if the target has a single parameter
200    /// .file directive, this is true for ELF targets.
201    bool HasSingleParameterDotFile;          // Defaults to true.
202
203    /// HasNoDeadStrip - True if this target supports the MachO .no_dead_strip
204    /// directive.
205    bool HasNoDeadStrip;                     // Defaults to false.
206
207    /// WeakRefDirective - This directive, if non-null, is used to declare a
208    /// global as being a weak undefined symbol.
209    const char *WeakRefDirective;            // Defaults to NULL.
210
211    /// WeakDefDirective - This directive, if non-null, is used to declare a
212    /// global as being a weak defined symbol.
213    const char *WeakDefDirective;            // Defaults to NULL.
214
215    /// LinkOnceDirective - This directive, if non-null is used to declare a
216    /// global as being a weak defined symbol.  This is used on cygwin/mingw.
217    const char *LinkOnceDirective;           // Defaults to NULL.
218
219    /// HiddenVisibilityAttr - This attribute, if not MCSA_Invalid, is used to
220    /// declare a symbol as having hidden visibility.
221    MCSymbolAttr HiddenVisibilityAttr;       // Defaults to MCSA_Hidden.
222
223    /// ProtectedVisibilityAttr - This attribute, if not MCSA_Invalid, is used
224    /// to declare a symbol as having protected visibility.
225    MCSymbolAttr ProtectedVisibilityAttr;    // Defaults to MCSA_Protected
226
227    //===--- Dwarf Emission Directives -----------------------------------===//
228
229    /// AbsoluteDebugSectionOffsets - True if we should emit abolute section
230    /// offsets for debug information.
231    bool AbsoluteDebugSectionOffsets;        // Defaults to false.
232
233    /// AbsoluteEHSectionOffsets - True if we should emit abolute section
234    /// offsets for EH information. Defaults to false.
235    bool AbsoluteEHSectionOffsets;
236
237    /// HasLEB128 - True if target asm supports leb128 directives.
238    bool HasLEB128;                          // Defaults to false.
239
240    /// hasDotLocAndDotFile - True if target asm supports .loc and .file
241    /// directives for emitting debugging information.
242    bool HasDotLocAndDotFile;                // Defaults to false.
243
244    /// SupportsDebugInformation - True if target supports emission of debugging
245    /// information.
246    bool SupportsDebugInformation;           // Defaults to false.
247
248    /// SupportsExceptionHandling - True if target supports exception handling.
249    ExceptionHandling::ExceptionsType ExceptionsType; // Defaults to None
250
251    /// RequiresFrameSection - true if the Dwarf2 output needs a frame section
252    bool DwarfRequiresFrameSection;          // Defaults to true.
253
254    /// DwarfUsesInlineInfoSection - True if DwarfDebugInlineSection is used to
255    /// encode inline subroutine information.
256    bool DwarfUsesInlineInfoSection;         // Defaults to false.
257
258    /// Is_EHSymbolPrivate - If set, the "_foo.eh" is made private so that it
259    /// doesn't show up in the symbol table of the object file.
260    bool Is_EHSymbolPrivate;                 // Defaults to true.
261
262    /// GlobalEHDirective - This is the directive used to make exception frame
263    /// tables globally visible.
264    const char *GlobalEHDirective;           // Defaults to NULL.
265
266    /// SupportsWeakEmptyEHFrame - True if target assembler and linker will
267    /// handle a weak_definition of constant 0 for an omitted EH frame.
268    bool SupportsWeakOmittedEHFrame;         // Defaults to true.
269
270    /// DwarfSectionOffsetDirective - Special section offset directive.
271    const char* DwarfSectionOffsetDirective; // Defaults to NULL
272
273    //===--- CBE Asm Translation Table -----------------------------------===//
274
275    const char *const *AsmTransCBE;          // Defaults to empty
276
277  public:
278    explicit MCAsmInfo();
279    virtual ~MCAsmInfo();
280
281    // FIXME: move these methods to DwarfPrinter when the JIT stops using them.
282    static unsigned getSLEB128Size(int Value);
283    static unsigned getULEB128Size(unsigned Value);
284
285    bool hasSubsectionsViaSymbols() const { return HasSubsectionsViaSymbols; }
286
287    // Data directive accessors.
288    //
289    const char *getData8bitsDirective(unsigned AS = 0) const {
290      return AS == 0 ? Data8bitsDirective : getDataASDirective(8, AS);
291    }
292    const char *getData16bitsDirective(unsigned AS = 0) const {
293      return AS == 0 ? Data16bitsDirective : getDataASDirective(16, AS);
294    }
295    const char *getData32bitsDirective(unsigned AS = 0) const {
296      return AS == 0 ? Data32bitsDirective : getDataASDirective(32, AS);
297    }
298    const char *getData64bitsDirective(unsigned AS = 0) const {
299      return AS == 0 ? Data64bitsDirective : getDataASDirective(64, AS);
300    }
301    const char *getGPRel32Directive() const { return GPRel32Directive; }
302
303    /// getNonexecutableStackSection - Targets can implement this method to
304    /// specify a section to switch to if the translation unit doesn't have any
305    /// trampolines that require an executable stack.
306    virtual MCSection *getNonexecutableStackSection(MCContext &Ctx) const {
307      return 0;
308    }
309
310    bool usesSunStyleELFSectionSwitchSyntax() const {
311      return SunStyleELFSectionSwitchSyntax;
312    }
313
314    bool usesELFSectionDirectiveForBSS() const {
315      return UsesELFSectionDirectiveForBSS;
316    }
317
318    // Accessors.
319    //
320    bool hasMachoZeroFillDirective() const { return HasMachoZeroFillDirective; }
321    bool hasStaticCtorDtorReferenceInStaticMode() const {
322      return HasStaticCtorDtorReferenceInStaticMode;
323    }
324    bool needsSet() const {
325      return NeedsSet;
326    }
327    unsigned getMaxInstLength() const {
328      return MaxInstLength;
329    }
330    const char *getPCSymbol() const {
331      return PCSymbol;
332    }
333    char getSeparatorChar() const {
334      return SeparatorChar;
335    }
336    unsigned getCommentColumn() const {
337      return CommentColumn;
338    }
339    const char *getCommentString() const {
340      return CommentString;
341    }
342    const char *getGlobalPrefix() const {
343      return GlobalPrefix;
344    }
345    const char *getPrivateGlobalPrefix() const {
346      return PrivateGlobalPrefix;
347    }
348    const char *getLinkerPrivateGlobalPrefix() const {
349      return LinkerPrivateGlobalPrefix;
350    }
351    const char *getInlineAsmStart() const {
352      return InlineAsmStart;
353    }
354    const char *getInlineAsmEnd() const {
355      return InlineAsmEnd;
356    }
357    unsigned getAssemblerDialect() const {
358      return AssemblerDialect;
359    }
360    bool doesAllowQuotesInName() const {
361      return AllowQuotesInName;
362    }
363    bool doesAllowNameToStartWithDigit() const {
364      return AllowNameToStartWithDigit;
365    }
366    const char *getZeroDirective() const {
367      return ZeroDirective;
368    }
369    const char *getAsciiDirective() const {
370      return AsciiDirective;
371    }
372    const char *getAscizDirective() const {
373      return AscizDirective;
374    }
375    const char *getAlignDirective() const {
376      return AlignDirective;
377    }
378    bool getAlignmentIsInBytes() const {
379      return AlignmentIsInBytes;
380    }
381    unsigned getTextAlignFillValue() const {
382      return TextAlignFillValue;
383    }
384    const char *getGlobalDirective() const {
385      return GlobalDirective;
386    }
387    const char *getExternDirective() const {
388      return ExternDirective;
389    }
390    const char *getSetDirective() const {
391      return SetDirective;
392    }
393    bool hasLCOMMDirective() const { return HasLCOMMDirective; }
394    bool hasDotTypeDotSizeDirective() const {return HasDotTypeDotSizeDirective;}
395    bool hasSingleParameterDotFile() const { return HasSingleParameterDotFile; }
396    bool hasNoDeadStrip() const { return HasNoDeadStrip; }
397    const char *getWeakRefDirective() const { return WeakRefDirective; }
398    const char *getWeakDefDirective() const { return WeakDefDirective; }
399    const char *getLinkOnceDirective() const { return LinkOnceDirective; }
400
401    MCSymbolAttr getHiddenVisibilityAttr() const { return HiddenVisibilityAttr;}
402    MCSymbolAttr getProtectedVisibilityAttr() const {
403      return ProtectedVisibilityAttr;
404    }
405    bool isAbsoluteDebugSectionOffsets() const {
406      return AbsoluteDebugSectionOffsets;
407    }
408    bool isAbsoluteEHSectionOffsets() const {
409      return AbsoluteEHSectionOffsets;
410    }
411    bool hasLEB128() const {
412      return HasLEB128;
413    }
414    bool hasDotLocAndDotFile() const {
415      return HasDotLocAndDotFile;
416    }
417    bool doesSupportDebugInformation() const {
418      return SupportsDebugInformation;
419    }
420    bool doesSupportExceptionHandling() const {
421      return ExceptionsType != ExceptionHandling::None;
422    }
423    ExceptionHandling::ExceptionsType getExceptionHandlingType() const {
424      return ExceptionsType;
425    }
426    bool doesDwarfRequireFrameSection() const {
427      return DwarfRequiresFrameSection;
428    }
429    bool doesDwarfUsesInlineInfoSection() const {
430      return DwarfUsesInlineInfoSection;
431    }
432    bool is_EHSymbolPrivate() const {
433      return Is_EHSymbolPrivate;
434    }
435    const char *getGlobalEHDirective() const {
436      return GlobalEHDirective;
437    }
438    bool getSupportsWeakOmittedEHFrame() const {
439      return SupportsWeakOmittedEHFrame;
440    }
441    const char *getDwarfSectionOffsetDirective() const {
442      return DwarfSectionOffsetDirective;
443    }
444    const char *const *getAsmCBE() const {
445      return AsmTransCBE;
446    }
447  };
448}
449
450#endif
451