AsmPrinter.h revision 366df7945f0e65052d2e1df701ae1fd16b943642 
1//===-- llvm/CodeGen/AsmPrinter.h - AsmPrinter Framework --------*- 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 base class for target specific
11// asm writers.  This class primarily handles common functionality used by
12// all asm writers.
13//
14//===----------------------------------------------------------------------===//
15
16#ifndef LLVM_CODEGEN_ASMPRINTER_H
17#define LLVM_CODEGEN_ASMPRINTER_H
18
19#include "llvm/CodeGen/MachineFunctionPass.h"
20#include "llvm/InlineAsm.h"
21#include "llvm/Support/DataTypes.h"
22#include "llvm/Support/ErrorHandling.h"
23
24namespace llvm {
25  class BlockAddress;
26  class GCStrategy;
27  class Constant;
28  class GCMetadataPrinter;
29  class GlobalValue;
30  class GlobalVariable;
31  class MachineBasicBlock;
32  class MachineFunction;
33  class MachineInstr;
34  class MachineLocation;
35  class MachineLoopInfo;
36  class MachineLoop;
37  class MachineConstantPoolValue;
38  class MachineJumpTableInfo;
39  class MachineModuleInfo;
40  class MachineMove;
41  class MCAsmInfo;
42  class MCContext;
43  class MCSection;
44  class MCStreamer;
45  class MCSymbol;
46  class MDNode;
47  class DwarfDebug;
48  class DwarfException;
49  class Mangler;
50  class TargetLoweringObjectFile;
51  class TargetData;
52  class TargetMachine;
53
54  /// AsmPrinter - This class is intended to be used as a driving class for all
55  /// asm writers.
56  class AsmPrinter : public MachineFunctionPass {
57  public:
58    /// Target machine description.
59    ///
60    TargetMachine &TM;
61
62    /// Target Asm Printer information.
63    ///
64    const MCAsmInfo *MAI;
65
66    /// OutContext - This is the context for the output file that we are
67    /// streaming.  This owns all of the global MC-related objects for the
68    /// generated translation unit.
69    MCContext &OutContext;
70
71    /// OutStreamer - This is the MCStreamer object for the file we are
72    /// generating.  This contains the transient state for the current
73    /// translation unit that we are generating (such as the current section
74    /// etc).
75    MCStreamer &OutStreamer;
76
77    /// The current machine function.
78    const MachineFunction *MF;
79
80    /// MMI - This is a pointer to the current MachineModuleInfo.
81    MachineModuleInfo *MMI;
82
83    /// Name-mangler for global names.
84    ///
85    Mangler *Mang;
86
87    /// The symbol for the current function. This is recalculated at the
88    /// beginning of each call to runOnMachineFunction().
89    ///
90    MCSymbol *CurrentFnSym;
91
92    /// The symbol used to represent the start of the current function for the
93    /// purpose of calculating its size (e.g. using the .size directive). By
94    /// default, this is equal to CurrentFnSym.
95    MCSymbol *CurrentFnSymForSize;
96
97  private:
98    // GCMetadataPrinters - The garbage collection metadata printer table.
99    void *GCMetadataPrinters;  // Really a DenseMap.
100
101    /// VerboseAsm - Emit comments in assembly output if this is true.
102    ///
103    bool VerboseAsm;
104    static char ID;
105
106    /// If VerboseAsm is set, a pointer to the loop info for this
107    /// function.
108    MachineLoopInfo *LI;
109
110    /// DD - If the target supports dwarf debug info, this pointer is non-null.
111    DwarfDebug *DD;
112
113    /// DE - If the target supports dwarf exception info, this pointer is
114    /// non-null.
115    DwarfException *DE;
116
117  protected:
118    explicit AsmPrinter(TargetMachine &TM, MCStreamer &Streamer);
119
120  public:
121    virtual ~AsmPrinter();
122
123    /// isVerbose - Return true if assembly output should contain comments.
124    ///
125    bool isVerbose() const { return VerboseAsm; }
126
127    /// getFunctionNumber - Return a unique ID for the current function.
128    ///
129    unsigned getFunctionNumber() const;
130
131    /// getObjFileLowering - Return information about object file lowering.
132    const TargetLoweringObjectFile &getObjFileLowering() const;
133
134    /// getTargetData - Return information about data layout.
135    const TargetData &getTargetData() const;
136
137    /// getCurrentSection() - Return the current section we are emitting to.
138    const MCSection *getCurrentSection() const;
139
140
141    //===------------------------------------------------------------------===//
142    // MachineFunctionPass Implementation.
143    //===------------------------------------------------------------------===//
144
145    /// getAnalysisUsage - Record analysis usage.
146    ///
147    void getAnalysisUsage(AnalysisUsage &AU) const;
148
149    /// doInitialization - Set up the AsmPrinter when we are working on a new
150    /// module.  If your pass overrides this, it must make sure to explicitly
151    /// call this implementation.
152    bool doInitialization(Module &M);
153
154    /// doFinalization - Shut down the asmprinter.  If you override this in your
155    /// pass, you must make sure to call it explicitly.
156    bool doFinalization(Module &M);
157
158    /// runOnMachineFunction - Emit the specified function out to the
159    /// OutStreamer.
160    virtual bool runOnMachineFunction(MachineFunction &MF) {
161      SetupMachineFunction(MF);
162      EmitFunctionHeader();
163      EmitFunctionBody();
164      return false;
165    }
166
167    //===------------------------------------------------------------------===//
168    // Coarse grained IR lowering routines.
169    //===------------------------------------------------------------------===//
170
171    /// SetupMachineFunction - This should be called when a new MachineFunction
172    /// is being processed from runOnMachineFunction.
173    void SetupMachineFunction(MachineFunction &MF);
174
175    /// EmitFunctionHeader - This method emits the header for the current
176    /// function.
177    void EmitFunctionHeader();
178
179    /// EmitFunctionBody - This method emits the body and trailer for a
180    /// function.
181    void EmitFunctionBody();
182
183    void emitPrologLabel(const MachineInstr &MI);
184
185    enum CFIMoveType {
186      CFI_M_None,
187      CFI_M_EH,
188      CFI_M_Debug
189    };
190    CFIMoveType needsCFIMoves();
191
192    bool needsSEHMoves();
193
194    /// needsRelocationsForDwarfStringPool - Specifies whether the object format
195    /// expects to use relocations to refer to debug entries. Alternatively we
196    /// emit section offsets in bytes from the start of the string pool.
197    bool needsRelocationsForDwarfStringPool() const;
198
199    /// EmitConstantPool - Print to the current output stream assembly
200    /// representations of the constants in the constant pool MCP. This is
201    /// used to print out constants which have been "spilled to memory" by
202    /// the code generator.
203    ///
204    virtual void EmitConstantPool();
205
206    /// EmitJumpTableInfo - Print assembly representations of the jump tables
207    /// used by the current function to the current output stream.
208    ///
209    void EmitJumpTableInfo();
210
211    /// EmitGlobalVariable - Emit the specified global variable to the .s file.
212    virtual void EmitGlobalVariable(const GlobalVariable *GV);
213
214    /// EmitSpecialLLVMGlobal - Check to see if the specified global is a
215    /// special global used by LLVM.  If so, emit it and return true, otherwise
216    /// do nothing and return false.
217    bool EmitSpecialLLVMGlobal(const GlobalVariable *GV);
218
219    /// EmitAlignment - Emit an alignment directive to the specified power of
220    /// two boundary.  For example, if you pass in 3 here, you will get an 8
221    /// byte alignment.  If a global value is specified, and if that global has
222    /// an explicit alignment requested, it will override the alignment request
223    /// if required for correctness.
224    ///
225    void EmitAlignment(unsigned NumBits, const GlobalValue *GV = 0) const;
226
227    /// EmitBasicBlockStart - This method prints the label for the specified
228    /// MachineBasicBlock, an alignment (if present) and a comment describing
229    /// it if appropriate.
230    void EmitBasicBlockStart(const MachineBasicBlock *MBB) const;
231
232    /// EmitGlobalConstant - Print a general LLVM constant to the .s file.
233    void EmitGlobalConstant(const Constant *CV, unsigned AddrSpace = 0);
234
235
236    //===------------------------------------------------------------------===//
237    // Overridable Hooks
238    //===------------------------------------------------------------------===//
239
240    // Targets can, or in the case of EmitInstruction, must implement these to
241    // customize output.
242
243    /// EmitStartOfAsmFile - This virtual method can be overridden by targets
244    /// that want to emit something at the start of their file.
245    virtual void EmitStartOfAsmFile(Module &) {}
246
247    /// EmitEndOfAsmFile - This virtual method can be overridden by targets that
248    /// want to emit something at the end of their file.
249    virtual void EmitEndOfAsmFile(Module &) {}
250
251    /// EmitFunctionBodyStart - Targets can override this to emit stuff before
252    /// the first basic block in the function.
253    virtual void EmitFunctionBodyStart() {}
254
255    /// EmitFunctionBodyEnd - Targets can override this to emit stuff after
256    /// the last basic block in the function.
257    virtual void EmitFunctionBodyEnd() {}
258
259    /// EmitInstruction - Targets should implement this to emit instructions.
260    virtual void EmitInstruction(const MachineInstr *) {
261      llvm_unreachable("EmitInstruction not implemented");
262    }
263
264    virtual void EmitFunctionEntryLabel();
265
266    virtual void EmitMachineConstantPoolValue(MachineConstantPoolValue *MCPV);
267
268    /// EmitXXStructor - Targets can override this to change how global
269    /// constants that are part of a C++ static/global constructor list are
270    /// emitted.
271    virtual void EmitXXStructor(const Constant *CV) {
272      EmitGlobalConstant(CV);
273    }
274
275    /// isBlockOnlyReachableByFallthough - Return true if the basic block has
276    /// exactly one predecessor and the control transfer mechanism between
277    /// the predecessor and this block is a fall-through.
278    virtual bool
279    isBlockOnlyReachableByFallthrough(const MachineBasicBlock *MBB) const;
280
281    //===------------------------------------------------------------------===//
282    // Symbol Lowering Routines.
283    //===------------------------------------------------------------------===//
284  public:
285
286    /// GetTempSymbol - Return the MCSymbol corresponding to the assembler
287    /// temporary label with the specified stem and unique ID.
288    MCSymbol *GetTempSymbol(StringRef Name, unsigned ID) const;
289
290    /// GetTempSymbol - Return an assembler temporary label with the specified
291    /// stem.
292    MCSymbol *GetTempSymbol(StringRef Name) const;
293
294
295    /// GetSymbolWithGlobalValueBase - Return the MCSymbol for a symbol with
296    /// global value name as its base, with the specified suffix, and where the
297    /// symbol is forced to have private linkage if ForcePrivate is true.
298    MCSymbol *GetSymbolWithGlobalValueBase(const GlobalValue *GV,
299                                           StringRef Suffix,
300                                           bool ForcePrivate = true) const;
301
302    /// GetExternalSymbolSymbol - Return the MCSymbol for the specified
303    /// ExternalSymbol.
304    MCSymbol *GetExternalSymbolSymbol(StringRef Sym) const;
305
306    /// GetCPISymbol - Return the symbol for the specified constant pool entry.
307    MCSymbol *GetCPISymbol(unsigned CPID) const;
308
309    /// GetJTISymbol - Return the symbol for the specified jump table entry.
310    MCSymbol *GetJTISymbol(unsigned JTID, bool isLinkerPrivate = false) const;
311
312    /// GetJTSetSymbol - Return the symbol for the specified jump table .set
313    /// FIXME: privatize to AsmPrinter.
314    MCSymbol *GetJTSetSymbol(unsigned UID, unsigned MBBID) const;
315
316    /// GetBlockAddressSymbol - Return the MCSymbol used to satisfy BlockAddress
317    /// uses of the specified basic block.
318    MCSymbol *GetBlockAddressSymbol(const BlockAddress *BA) const;
319    MCSymbol *GetBlockAddressSymbol(const BasicBlock *BB) const;
320
321    //===------------------------------------------------------------------===//
322    // Emission Helper Routines.
323    //===------------------------------------------------------------------===//
324  public:
325    /// printOffset - This is just convenient handler for printing offsets.
326    void printOffset(int64_t Offset, raw_ostream &OS) const;
327
328    /// EmitInt8 - Emit a byte directive and value.
329    ///
330    void EmitInt8(int Value) const;
331
332    /// EmitInt16 - Emit a short directive and value.
333    ///
334    void EmitInt16(int Value) const;
335
336    /// EmitInt32 - Emit a long directive and value.
337    ///
338    void EmitInt32(int Value) const;
339
340    /// EmitLabelDifference - Emit something like ".long Hi-Lo" where the size
341    /// in bytes of the directive is specified by Size and Hi/Lo specify the
342    /// labels.  This implicitly uses .set if it is available.
343    void EmitLabelDifference(const MCSymbol *Hi, const MCSymbol *Lo,
344                             unsigned Size) const;
345
346    /// EmitLabelOffsetDifference - Emit something like ".long Hi+Offset-Lo"
347    /// where the size in bytes of the directive is specified by Size and Hi/Lo
348    /// specify the labels.  This implicitly uses .set if it is available.
349    void EmitLabelOffsetDifference(const MCSymbol *Hi, uint64_t Offset,
350                                   const MCSymbol *Lo, unsigned Size) const;
351
352    /// EmitLabelPlusOffset - Emit something like ".long Label+Offset"
353    /// where the size in bytes of the directive is specified by Size and Label
354    /// specifies the label.  This implicitly uses .set if it is available.
355    void EmitLabelPlusOffset(const MCSymbol *Label, uint64_t Offset,
356                                   unsigned Size) const;
357
358    /// EmitLabelReference - Emit something like ".long Label"
359    /// where the size in bytes of the directive is specified by Size and Label
360    /// specifies the label.
361    void EmitLabelReference(const MCSymbol *Label, unsigned Size) const {
362      EmitLabelPlusOffset(Label, 0, Size);
363    }
364
365    //===------------------------------------------------------------------===//
366    // Dwarf Emission Helper Routines
367    //===------------------------------------------------------------------===//
368
369    /// EmitSLEB128 - emit the specified signed leb128 value.
370    void EmitSLEB128(int Value, const char *Desc = 0) const;
371
372    /// EmitULEB128 - emit the specified unsigned leb128 value.
373    void EmitULEB128(unsigned Value, const char *Desc = 0,
374                     unsigned PadTo = 0) const;
375
376    /// EmitCFAByte - Emit a .byte 42 directive for a DW_CFA_xxx value.
377    void EmitCFAByte(unsigned Val) const;
378
379    /// EmitEncodingByte - Emit a .byte 42 directive that corresponds to an
380    /// encoding.  If verbose assembly output is enabled, we output comments
381    /// describing the encoding.  Desc is a string saying what the encoding is
382    /// specifying (e.g. "LSDA").
383    void EmitEncodingByte(unsigned Val, const char *Desc = 0) const;
384
385    /// GetSizeOfEncodedValue - Return the size of the encoding in bytes.
386    unsigned GetSizeOfEncodedValue(unsigned Encoding) const;
387
388    /// EmitReference - Emit a reference to a label with a specified encoding.
389    ///
390    void EmitReference(const MCSymbol *Sym, unsigned Encoding) const;
391    void EmitReference(const GlobalValue *GV, unsigned Encoding) const;
392
393    /// EmitSectionOffset - Emit the 4-byte offset of Label from the start of
394    /// its section.  This can be done with a special directive if the target
395    /// supports it (e.g. cygwin) or by emitting it as an offset from a label at
396    /// the start of the section.
397    ///
398    /// SectionLabel is a temporary label emitted at the start of the section
399    /// that Label lives in.
400    void EmitSectionOffset(const MCSymbol *Label,
401                           const MCSymbol *SectionLabel) const;
402
403    /// getDebugValueLocation - Get location information encoded by DBG_VALUE
404    /// operands.
405    virtual MachineLocation getDebugValueLocation(const MachineInstr *MI) const;
406
407    /// getISAEncoding - Get the value for DW_AT_APPLE_isa. Zero if no isa
408    /// encoding specified.
409    virtual unsigned getISAEncoding() { return 0; }
410
411    /// EmitDwarfRegOp - Emit dwarf register operation.
412    virtual void EmitDwarfRegOp(const MachineLocation &MLoc) const;
413
414    //===------------------------------------------------------------------===//
415    // Dwarf Lowering Routines
416    //===------------------------------------------------------------------===//
417
418    /// EmitCFIFrameMove - Emit frame instruction to describe the layout of the
419    /// frame.
420    void EmitCFIFrameMove(const MachineMove &Move) const;
421
422    //===------------------------------------------------------------------===//
423    // Inline Asm Support
424    //===------------------------------------------------------------------===//
425  public:
426    // These are hooks that targets can override to implement inline asm
427    // support.  These should probably be moved out of AsmPrinter someday.
428
429    /// PrintSpecial - Print information related to the specified machine instr
430    /// that is independent of the operand, and may be independent of the instr
431    /// itself.  This can be useful for portably encoding the comment character
432    /// or other bits of target-specific knowledge into the asmstrings.  The
433    /// syntax used is ${:comment}.  Targets can override this to add support
434    /// for their own strange codes.
435    virtual void PrintSpecial(const MachineInstr *MI, raw_ostream &OS,
436                              const char *Code) const;
437
438    /// PrintAsmOperand - Print the specified operand of MI, an INLINEASM
439    /// instruction, using the specified assembler variant.  Targets should
440    /// override this to format as appropriate.  This method can return true if
441    /// the operand is erroneous.
442    virtual bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
443                                 unsigned AsmVariant, const char *ExtraCode,
444                                 raw_ostream &OS);
445
446    /// PrintAsmMemoryOperand - Print the specified operand of MI, an INLINEASM
447    /// instruction, using the specified assembler variant as an address.
448    /// Targets should override this to format as appropriate.  This method can
449    /// return true if the operand is erroneous.
450    virtual bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
451                                       unsigned AsmVariant,
452                                       const char *ExtraCode,
453                                       raw_ostream &OS);
454
455  private:
456    /// Private state for PrintSpecial()
457    // Assign a unique ID to this machine instruction.
458    mutable const MachineInstr *LastMI;
459    mutable unsigned LastFn;
460    mutable unsigned Counter;
461    mutable unsigned SetCounter;
462
463    /// EmitInlineAsm - Emit a blob of inline asm to the output streamer.
464    void EmitInlineAsm(StringRef Str, const MDNode *LocMDNode = 0,
465                    InlineAsm::AsmDialect AsmDialect = InlineAsm::AD_ATT) const;
466
467    /// EmitInlineAsm - This method formats and emits the specified machine
468    /// instruction that is an inline asm.
469    void EmitInlineAsm(const MachineInstr *MI) const;
470
471    //===------------------------------------------------------------------===//
472    // Internal Implementation Details
473    //===------------------------------------------------------------------===//
474
475    /// EmitVisibility - This emits visibility information about symbol, if
476    /// this is suported by the target.
477    void EmitVisibility(MCSymbol *Sym, unsigned Visibility,
478                        bool IsDefinition = true) const;
479
480    void EmitLinkage(unsigned Linkage, MCSymbol *GVSym) const;
481
482    void EmitJumpTableEntry(const MachineJumpTableInfo *MJTI,
483                            const MachineBasicBlock *MBB,
484                            unsigned uid) const;
485    void EmitLLVMUsedList(const Constant *List);
486    void EmitXXStructorList(const Constant *List, bool isCtor);
487    GCMetadataPrinter *GetOrCreateGCPrinter(GCStrategy *C);
488  };
489}
490
491#endif
492