1//===-- llvm/Function.h - Class to represent a single function --*- 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 the declaration of the Function class, which represents a
11// single function/procedure in LLVM.
12//
13// A function basically consists of a list of basic blocks, a list of arguments,
14// and a symbol table.
15//
16//===----------------------------------------------------------------------===//
17
18#ifndef LLVM_IR_FUNCTION_H
19#define LLVM_IR_FUNCTION_H
20
21#include "llvm/IR/Argument.h"
22#include "llvm/IR/Attributes.h"
23#include "llvm/IR/BasicBlock.h"
24#include "llvm/IR/CallingConv.h"
25#include "llvm/IR/GlobalValue.h"
26#include "llvm/Support/Compiler.h"
27
28namespace llvm {
29
30class FunctionType;
31class LLVMContext;
32
33// Traits for intrusive list of basic blocks...
34template<> struct ilist_traits<BasicBlock>
35  : public SymbolTableListTraits<BasicBlock, Function> {
36
37  // createSentinel is used to get hold of the node that marks the end of the
38  // list... (same trick used here as in ilist_traits<Instruction>)
39  BasicBlock *createSentinel() const {
40    return static_cast<BasicBlock*>(&Sentinel);
41  }
42  static void destroySentinel(BasicBlock*) {}
43
44  BasicBlock *provideInitialHead() const { return createSentinel(); }
45  BasicBlock *ensureHead(BasicBlock*) const { return createSentinel(); }
46  static void noteHead(BasicBlock*, BasicBlock*) {}
47
48  static ValueSymbolTable *getSymTab(Function *ItemParent);
49private:
50  mutable ilist_half_node<BasicBlock> Sentinel;
51};
52
53template<> struct ilist_traits<Argument>
54  : public SymbolTableListTraits<Argument, Function> {
55
56  Argument *createSentinel() const {
57    return static_cast<Argument*>(&Sentinel);
58  }
59  static void destroySentinel(Argument*) {}
60
61  Argument *provideInitialHead() const { return createSentinel(); }
62  Argument *ensureHead(Argument*) const { return createSentinel(); }
63  static void noteHead(Argument*, Argument*) {}
64
65  static ValueSymbolTable *getSymTab(Function *ItemParent);
66private:
67  mutable ilist_half_node<Argument> Sentinel;
68};
69
70class Function : public GlobalValue,
71                 public ilist_node<Function> {
72public:
73  typedef iplist<Argument> ArgumentListType;
74  typedef iplist<BasicBlock> BasicBlockListType;
75
76  // BasicBlock iterators...
77  typedef BasicBlockListType::iterator iterator;
78  typedef BasicBlockListType::const_iterator const_iterator;
79
80  typedef ArgumentListType::iterator arg_iterator;
81  typedef ArgumentListType::const_iterator const_arg_iterator;
82
83private:
84  // Important things that make up a function!
85  BasicBlockListType  BasicBlocks;        ///< The basic blocks
86  mutable ArgumentListType ArgumentList;  ///< The formal arguments
87  ValueSymbolTable *SymTab;               ///< Symbol table of args/instructions
88  AttributeSet AttributeSets;             ///< Parameter attributes
89
90  // HasLazyArguments is stored in Value::SubclassData.
91  /*bool HasLazyArguments;*/
92
93  // The Calling Convention is stored in Value::SubclassData.
94  /*CallingConv::ID CallingConvention;*/
95
96  friend class SymbolTableListTraits<Function, Module>;
97
98  void setParent(Module *parent);
99
100  /// hasLazyArguments/CheckLazyArguments - The argument list of a function is
101  /// built on demand, so that the list isn't allocated until the first client
102  /// needs it.  The hasLazyArguments predicate returns true if the arg list
103  /// hasn't been set up yet.
104  bool hasLazyArguments() const {
105    return getSubclassDataFromValue() & 1;
106  }
107  void CheckLazyArguments() const {
108    if (hasLazyArguments())
109      BuildLazyArguments();
110  }
111  void BuildLazyArguments() const;
112
113  Function(const Function&) LLVM_DELETED_FUNCTION;
114  void operator=(const Function&) LLVM_DELETED_FUNCTION;
115
116  /// Do the actual lookup of an intrinsic ID when the query could not be
117  /// answered from the cache.
118  unsigned lookupIntrinsicID() const LLVM_READONLY;
119
120  /// Function ctor - If the (optional) Module argument is specified, the
121  /// function is automatically inserted into the end of the function list for
122  /// the module.
123  ///
124  Function(FunctionType *Ty, LinkageTypes Linkage,
125           const Twine &N = "", Module *M = 0);
126
127public:
128  static Function *Create(FunctionType *Ty, LinkageTypes Linkage,
129                          const Twine &N = "", Module *M = 0) {
130    return new(0) Function(Ty, Linkage, N, M);
131  }
132
133  ~Function();
134
135  Type *getReturnType() const;           // Return the type of the ret val
136  FunctionType *getFunctionType() const; // Return the FunctionType for me
137
138  /// getContext - Return a pointer to the LLVMContext associated with this
139  /// function, or NULL if this function is not bound to a context yet.
140  LLVMContext &getContext() const;
141
142  /// isVarArg - Return true if this function takes a variable number of
143  /// arguments.
144  bool isVarArg() const;
145
146  /// getIntrinsicID - This method returns the ID number of the specified
147  /// function, or Intrinsic::not_intrinsic if the function is not an
148  /// intrinsic, or if the pointer is null.  This value is always defined to be
149  /// zero to allow easy checking for whether a function is intrinsic or not.
150  /// The particular intrinsic functions which correspond to this value are
151  /// defined in llvm/Intrinsics.h.  Results are cached in the LLVM context,
152  /// subsequent requests for the same ID return results much faster from the
153  /// cache.
154  ///
155  unsigned getIntrinsicID() const LLVM_READONLY;
156  bool isIntrinsic() const { return getName().startswith("llvm."); }
157
158  /// getCallingConv()/setCallingConv(CC) - These method get and set the
159  /// calling convention of this function.  The enum values for the known
160  /// calling conventions are defined in CallingConv.h.
161  CallingConv::ID getCallingConv() const {
162    return static_cast<CallingConv::ID>(getSubclassDataFromValue() >> 1);
163  }
164  void setCallingConv(CallingConv::ID CC) {
165    setValueSubclassData((getSubclassDataFromValue() & 1) |
166                         (static_cast<unsigned>(CC) << 1));
167  }
168
169  /// getAttributes - Return the attribute list for this Function.
170  ///
171  AttributeSet getAttributes() const { return AttributeSets; }
172
173  /// setAttributes - Set the attribute list for this Function.
174  ///
175  void setAttributes(AttributeSet attrs) { AttributeSets = attrs; }
176
177  /// addFnAttr - Add function attributes to this function.
178  ///
179  void addFnAttr(Attribute::AttrKind N) {
180    setAttributes(AttributeSets.addAttribute(getContext(),
181                                             AttributeSet::FunctionIndex, N));
182  }
183
184  /// addFnAttr - Add function attributes to this function.
185  ///
186  void addFnAttr(StringRef Kind) {
187    setAttributes(
188      AttributeSets.addAttribute(getContext(),
189                                 AttributeSet::FunctionIndex, Kind));
190  }
191
192  /// \brief Return true if the function has the attribute.
193  bool hasFnAttribute(Attribute::AttrKind Kind) const {
194    return AttributeSets.hasAttribute(AttributeSet::FunctionIndex, Kind);
195  }
196  bool hasFnAttribute(StringRef Kind) const {
197    return AttributeSets.hasAttribute(AttributeSet::FunctionIndex, Kind);
198  }
199
200  /// hasGC/getGC/setGC/clearGC - The name of the garbage collection algorithm
201  ///                             to use during code generation.
202  bool hasGC() const;
203  const char *getGC() const;
204  void setGC(const char *Str);
205  void clearGC();
206
207  /// @brief adds the attribute to the list of attributes.
208  void addAttribute(unsigned i, Attribute::AttrKind attr);
209
210  /// @brief adds the attributes to the list of attributes.
211  void addAttributes(unsigned i, AttributeSet attrs);
212
213  /// @brief removes the attributes from the list of attributes.
214  void removeAttributes(unsigned i, AttributeSet attr);
215
216  /// @brief Extract the alignment for a call or parameter (0=unknown).
217  unsigned getParamAlignment(unsigned i) const {
218    return AttributeSets.getParamAlignment(i);
219  }
220
221  /// @brief Determine if the function does not access memory.
222  bool doesNotAccessMemory() const {
223    return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
224                                      Attribute::ReadNone);
225  }
226  void setDoesNotAccessMemory() {
227    addFnAttr(Attribute::ReadNone);
228  }
229
230  /// @brief Determine if the function does not access or only reads memory.
231  bool onlyReadsMemory() const {
232    return doesNotAccessMemory() ||
233      AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
234                                 Attribute::ReadOnly);
235  }
236  void setOnlyReadsMemory() {
237    addFnAttr(Attribute::ReadOnly);
238  }
239
240  /// @brief Determine if the function cannot return.
241  bool doesNotReturn() const {
242    return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
243                                      Attribute::NoReturn);
244  }
245  void setDoesNotReturn() {
246    addFnAttr(Attribute::NoReturn);
247  }
248
249  /// @brief Determine if the function cannot unwind.
250  bool doesNotThrow() const {
251    return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
252                                      Attribute::NoUnwind);
253  }
254  void setDoesNotThrow() {
255    addFnAttr(Attribute::NoUnwind);
256  }
257
258  /// @brief Determine if the call cannot be duplicated.
259  bool cannotDuplicate() const {
260    return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
261                                      Attribute::NoDuplicate);
262  }
263  void setCannotDuplicate() {
264    addFnAttr(Attribute::NoDuplicate);
265  }
266
267  /// @brief True if the ABI mandates (or the user requested) that this
268  /// function be in a unwind table.
269  bool hasUWTable() const {
270    return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
271                                      Attribute::UWTable);
272  }
273  void setHasUWTable() {
274    addFnAttr(Attribute::UWTable);
275  }
276
277  /// @brief True if this function needs an unwind table.
278  bool needsUnwindTableEntry() const {
279    return hasUWTable() || !doesNotThrow();
280  }
281
282  /// @brief Determine if the function returns a structure through first
283  /// pointer argument.
284  bool hasStructRetAttr() const {
285    return AttributeSets.hasAttribute(1, Attribute::StructRet);
286  }
287
288  /// @brief Determine if the parameter does not alias other parameters.
289  /// @param n The parameter to check. 1 is the first parameter, 0 is the return
290  bool doesNotAlias(unsigned n) const {
291    return AttributeSets.hasAttribute(n, Attribute::NoAlias);
292  }
293  void setDoesNotAlias(unsigned n) {
294    addAttribute(n, Attribute::NoAlias);
295  }
296
297  /// @brief Determine if the parameter can be captured.
298  /// @param n The parameter to check. 1 is the first parameter, 0 is the return
299  bool doesNotCapture(unsigned n) const {
300    return AttributeSets.hasAttribute(n, Attribute::NoCapture);
301  }
302  void setDoesNotCapture(unsigned n) {
303    addAttribute(n, Attribute::NoCapture);
304  }
305
306  /// copyAttributesFrom - copy all additional attributes (those not needed to
307  /// create a Function) from the Function Src to this one.
308  void copyAttributesFrom(const GlobalValue *Src);
309
310  /// deleteBody - This method deletes the body of the function, and converts
311  /// the linkage to external.
312  ///
313  void deleteBody() {
314    dropAllReferences();
315    setLinkage(ExternalLinkage);
316  }
317
318  /// removeFromParent - This method unlinks 'this' from the containing module,
319  /// but does not delete it.
320  ///
321  virtual void removeFromParent();
322
323  /// eraseFromParent - This method unlinks 'this' from the containing module
324  /// and deletes it.
325  ///
326  virtual void eraseFromParent();
327
328
329  /// Get the underlying elements of the Function... the basic block list is
330  /// empty for external functions.
331  ///
332  const ArgumentListType &getArgumentList() const {
333    CheckLazyArguments();
334    return ArgumentList;
335  }
336  ArgumentListType &getArgumentList() {
337    CheckLazyArguments();
338    return ArgumentList;
339  }
340  static iplist<Argument> Function::*getSublistAccess(Argument*) {
341    return &Function::ArgumentList;
342  }
343
344  const BasicBlockListType &getBasicBlockList() const { return BasicBlocks; }
345        BasicBlockListType &getBasicBlockList()       { return BasicBlocks; }
346  static iplist<BasicBlock> Function::*getSublistAccess(BasicBlock*) {
347    return &Function::BasicBlocks;
348  }
349
350  const BasicBlock       &getEntryBlock() const   { return front(); }
351        BasicBlock       &getEntryBlock()         { return front(); }
352
353  //===--------------------------------------------------------------------===//
354  // Symbol Table Accessing functions...
355
356  /// getSymbolTable() - Return the symbol table...
357  ///
358  inline       ValueSymbolTable &getValueSymbolTable()       { return *SymTab; }
359  inline const ValueSymbolTable &getValueSymbolTable() const { return *SymTab; }
360
361
362  //===--------------------------------------------------------------------===//
363  // BasicBlock iterator forwarding functions
364  //
365  iterator                begin()       { return BasicBlocks.begin(); }
366  const_iterator          begin() const { return BasicBlocks.begin(); }
367  iterator                end  ()       { return BasicBlocks.end();   }
368  const_iterator          end  () const { return BasicBlocks.end();   }
369
370  size_t                   size() const { return BasicBlocks.size();  }
371  bool                    empty() const { return BasicBlocks.empty(); }
372  const BasicBlock       &front() const { return BasicBlocks.front(); }
373        BasicBlock       &front()       { return BasicBlocks.front(); }
374  const BasicBlock        &back() const { return BasicBlocks.back();  }
375        BasicBlock        &back()       { return BasicBlocks.back();  }
376
377  //===--------------------------------------------------------------------===//
378  // Argument iterator forwarding functions
379  //
380  arg_iterator arg_begin() {
381    CheckLazyArguments();
382    return ArgumentList.begin();
383  }
384  const_arg_iterator arg_begin() const {
385    CheckLazyArguments();
386    return ArgumentList.begin();
387  }
388  arg_iterator arg_end() {
389    CheckLazyArguments();
390    return ArgumentList.end();
391  }
392  const_arg_iterator arg_end() const {
393    CheckLazyArguments();
394    return ArgumentList.end();
395  }
396
397  size_t arg_size() const;
398  bool arg_empty() const;
399
400  /// viewCFG - This function is meant for use from the debugger.  You can just
401  /// say 'call F->viewCFG()' and a ghostview window should pop up from the
402  /// program, displaying the CFG of the current function with the code for each
403  /// basic block inside.  This depends on there being a 'dot' and 'gv' program
404  /// in your path.
405  ///
406  void viewCFG() const;
407
408  /// viewCFGOnly - This function is meant for use from the debugger.  It works
409  /// just like viewCFG, but it does not include the contents of basic blocks
410  /// into the nodes, just the label.  If you are only interested in the CFG
411  /// this can make the graph smaller.
412  ///
413  void viewCFGOnly() const;
414
415  /// Methods for support type inquiry through isa, cast, and dyn_cast:
416  static inline bool classof(const Value *V) {
417    return V->getValueID() == Value::FunctionVal;
418  }
419
420  /// dropAllReferences() - This method causes all the subinstructions to "let
421  /// go" of all references that they are maintaining.  This allows one to
422  /// 'delete' a whole module at a time, even though there may be circular
423  /// references... first all references are dropped, and all use counts go to
424  /// zero.  Then everything is deleted for real.  Note that no operations are
425  /// valid on an object that has "dropped all references", except operator
426  /// delete.
427  ///
428  /// Since no other object in the module can have references into the body of a
429  /// function, dropping all references deletes the entire body of the function,
430  /// including any contained basic blocks.
431  ///
432  void dropAllReferences();
433
434  /// hasAddressTaken - returns true if there are any uses of this function
435  /// other than direct calls or invokes to it, or blockaddress expressions.
436  /// Optionally passes back an offending user for diagnostic purposes.
437  ///
438  bool hasAddressTaken(const User** = 0) const;
439
440  /// isDefTriviallyDead - Return true if it is trivially safe to remove
441  /// this function definition from the module (because it isn't externally
442  /// visible, does not have its address taken, and has no callers).  To make
443  /// this more accurate, call removeDeadConstantUsers first.
444  bool isDefTriviallyDead() const;
445
446  /// callsFunctionThatReturnsTwice - Return true if the function has a call to
447  /// setjmp or other function that gcc recognizes as "returning twice".
448  bool callsFunctionThatReturnsTwice() const;
449
450private:
451  // Shadow Value::setValueSubclassData with a private forwarding method so that
452  // subclasses cannot accidentally use it.
453  void setValueSubclassData(unsigned short D) {
454    Value::setValueSubclassData(D);
455  }
456};
457
458inline ValueSymbolTable *
459ilist_traits<BasicBlock>::getSymTab(Function *F) {
460  return F ? &F->getValueSymbolTable() : 0;
461}
462
463inline ValueSymbolTable *
464ilist_traits<Argument>::getSymTab(Function *F) {
465  return F ? &F->getValueSymbolTable() : 0;
466}
467
468} // End llvm namespace
469
470#endif
471