1//===-- Function.cpp - Implement the Global object classes ----------------===//
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 implements the Function class for the VMCore library.
11//
12//===----------------------------------------------------------------------===//
13
14#include "llvm/Module.h"
15#include "llvm/DerivedTypes.h"
16#include "llvm/IntrinsicInst.h"
17#include "llvm/LLVMContext.h"
18#include "llvm/CodeGen/ValueTypes.h"
19#include "llvm/Support/CallSite.h"
20#include "llvm/Support/InstIterator.h"
21#include "llvm/Support/LeakDetector.h"
22#include "llvm/Support/ManagedStatic.h"
23#include "llvm/Support/StringPool.h"
24#include "llvm/Support/RWMutex.h"
25#include "llvm/Support/Threading.h"
26#include "SymbolTableListTraitsImpl.h"
27#include "llvm/ADT/DenseMap.h"
28#include "llvm/ADT/STLExtras.h"
29#include "llvm/ADT/StringExtras.h"
30using namespace llvm;
31
32
33// Explicit instantiations of SymbolTableListTraits since some of the methods
34// are not in the public header file...
35template class llvm::SymbolTableListTraits<Argument, Function>;
36template class llvm::SymbolTableListTraits<BasicBlock, Function>;
37
38//===----------------------------------------------------------------------===//
39// Argument Implementation
40//===----------------------------------------------------------------------===//
41
42Argument::Argument(Type *Ty, const Twine &Name, Function *Par)
43  : Value(Ty, Value::ArgumentVal) {
44  Parent = 0;
45
46  // Make sure that we get added to a function
47  LeakDetector::addGarbageObject(this);
48
49  if (Par)
50    Par->getArgumentList().push_back(this);
51  setName(Name);
52}
53
54void Argument::setParent(Function *parent) {
55  if (getParent())
56    LeakDetector::addGarbageObject(this);
57  Parent = parent;
58  if (getParent())
59    LeakDetector::removeGarbageObject(this);
60}
61
62/// getArgNo - Return the index of this formal argument in its containing
63/// function.  For example in "void foo(int a, float b)" a is 0 and b is 1.
64unsigned Argument::getArgNo() const {
65  const Function *F = getParent();
66  assert(F && "Argument is not in a function");
67
68  Function::const_arg_iterator AI = F->arg_begin();
69  unsigned ArgIdx = 0;
70  for (; &*AI != this; ++AI)
71    ++ArgIdx;
72
73  return ArgIdx;
74}
75
76/// hasByValAttr - Return true if this argument has the byval attribute on it
77/// in its containing function.
78bool Argument::hasByValAttr() const {
79  if (!getType()->isPointerTy()) return false;
80  return getParent()->paramHasAttr(getArgNo()+1, Attribute::ByVal);
81}
82
83unsigned Argument::getParamAlignment() const {
84  assert(getType()->isPointerTy() && "Only pointers have alignments");
85  return getParent()->getParamAlignment(getArgNo()+1);
86
87}
88
89/// hasNestAttr - Return true if this argument has the nest attribute on
90/// it in its containing function.
91bool Argument::hasNestAttr() const {
92  if (!getType()->isPointerTy()) return false;
93  return getParent()->paramHasAttr(getArgNo()+1, Attribute::Nest);
94}
95
96/// hasNoAliasAttr - Return true if this argument has the noalias attribute on
97/// it in its containing function.
98bool Argument::hasNoAliasAttr() const {
99  if (!getType()->isPointerTy()) return false;
100  return getParent()->paramHasAttr(getArgNo()+1, Attribute::NoAlias);
101}
102
103/// hasNoCaptureAttr - Return true if this argument has the nocapture attribute
104/// on it in its containing function.
105bool Argument::hasNoCaptureAttr() const {
106  if (!getType()->isPointerTy()) return false;
107  return getParent()->paramHasAttr(getArgNo()+1, Attribute::NoCapture);
108}
109
110/// hasSRetAttr - Return true if this argument has the sret attribute on
111/// it in its containing function.
112bool Argument::hasStructRetAttr() const {
113  if (!getType()->isPointerTy()) return false;
114  if (this != getParent()->arg_begin())
115    return false; // StructRet param must be first param
116  return getParent()->paramHasAttr(1, Attribute::StructRet);
117}
118
119/// addAttr - Add a Attribute to an argument
120void Argument::addAttr(Attributes attr) {
121  getParent()->addAttribute(getArgNo() + 1, attr);
122}
123
124/// removeAttr - Remove a Attribute from an argument
125void Argument::removeAttr(Attributes attr) {
126  getParent()->removeAttribute(getArgNo() + 1, attr);
127}
128
129
130//===----------------------------------------------------------------------===//
131// Helper Methods in Function
132//===----------------------------------------------------------------------===//
133
134LLVMContext &Function::getContext() const {
135  return getType()->getContext();
136}
137
138FunctionType *Function::getFunctionType() const {
139  return cast<FunctionType>(getType()->getElementType());
140}
141
142bool Function::isVarArg() const {
143  return getFunctionType()->isVarArg();
144}
145
146Type *Function::getReturnType() const {
147  return getFunctionType()->getReturnType();
148}
149
150void Function::removeFromParent() {
151  getParent()->getFunctionList().remove(this);
152}
153
154void Function::eraseFromParent() {
155  getParent()->getFunctionList().erase(this);
156}
157
158//===----------------------------------------------------------------------===//
159// Function Implementation
160//===----------------------------------------------------------------------===//
161
162Function::Function(FunctionType *Ty, LinkageTypes Linkage,
163                   const Twine &name, Module *ParentModule)
164  : GlobalValue(PointerType::getUnqual(Ty),
165                Value::FunctionVal, 0, 0, Linkage, name) {
166  assert(FunctionType::isValidReturnType(getReturnType()) &&
167         "invalid return type");
168  SymTab = new ValueSymbolTable();
169
170  // If the function has arguments, mark them as lazily built.
171  if (Ty->getNumParams())
172    setValueSubclassData(1);   // Set the "has lazy arguments" bit.
173
174  // Make sure that we get added to a function
175  LeakDetector::addGarbageObject(this);
176
177  if (ParentModule)
178    ParentModule->getFunctionList().push_back(this);
179
180  // Ensure intrinsics have the right parameter attributes.
181  intrinsicID = initIntrinsicID();
182  if (intrinsicID)
183    setAttributes(Intrinsic::getAttributes(Intrinsic::ID(intrinsicID)));
184}
185
186Function::~Function() {
187  dropAllReferences();    // After this it is safe to delete instructions.
188
189  // Delete all of the method arguments and unlink from symbol table...
190  ArgumentList.clear();
191  delete SymTab;
192
193  // Remove the function from the on-the-side GC table.
194  clearGC();
195}
196
197void Function::BuildLazyArguments() const {
198  // Create the arguments vector, all arguments start out unnamed.
199  FunctionType *FT = getFunctionType();
200  for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i) {
201    assert(!FT->getParamType(i)->isVoidTy() &&
202           "Cannot have void typed arguments!");
203    ArgumentList.push_back(new Argument(FT->getParamType(i)));
204  }
205
206  // Clear the lazy arguments bit.
207  unsigned SDC = getSubclassDataFromValue();
208  const_cast<Function*>(this)->setValueSubclassData(SDC &= ~1);
209}
210
211size_t Function::arg_size() const {
212  return getFunctionType()->getNumParams();
213}
214bool Function::arg_empty() const {
215  return getFunctionType()->getNumParams() == 0;
216}
217
218void Function::setParent(Module *parent) {
219  if (getParent())
220    LeakDetector::addGarbageObject(this);
221  Parent = parent;
222  if (getParent())
223    LeakDetector::removeGarbageObject(this);
224}
225
226// dropAllReferences() - This function causes all the subinstructions to "let
227// go" of all references that they are maintaining.  This allows one to
228// 'delete' a whole class at a time, even though there may be circular
229// references... first all references are dropped, and all use counts go to
230// zero.  Then everything is deleted for real.  Note that no operations are
231// valid on an object that has "dropped all references", except operator
232// delete.
233//
234void Function::dropAllReferences() {
235  for (iterator I = begin(), E = end(); I != E; ++I)
236    I->dropAllReferences();
237
238  // Delete all basic blocks. They are now unused, except possibly by
239  // blockaddresses, but BasicBlock's destructor takes care of those.
240  while (!BasicBlocks.empty())
241    BasicBlocks.begin()->eraseFromParent();
242}
243
244void Function::addAttribute(unsigned i, Attributes attr) {
245  AttrListPtr PAL = getAttributes();
246  PAL = PAL.addAttr(i, attr);
247  setAttributes(PAL);
248}
249
250void Function::removeAttribute(unsigned i, Attributes attr) {
251  AttrListPtr PAL = getAttributes();
252  PAL = PAL.removeAttr(i, attr);
253  setAttributes(PAL);
254}
255
256// Maintain the GC name for each function in an on-the-side table. This saves
257// allocating an additional word in Function for programs which do not use GC
258// (i.e., most programs) at the cost of increased overhead for clients which do
259// use GC.
260static DenseMap<const Function*,PooledStringPtr> *GCNames;
261static StringPool *GCNamePool;
262static ManagedStatic<sys::SmartRWMutex<true> > GCLock;
263
264bool Function::hasGC() const {
265  sys::SmartScopedReader<true> Reader(*GCLock);
266  return GCNames && GCNames->count(this);
267}
268
269const char *Function::getGC() const {
270  assert(hasGC() && "Function has no collector");
271  sys::SmartScopedReader<true> Reader(*GCLock);
272  return *(*GCNames)[this];
273}
274
275void Function::setGC(const char *Str) {
276  sys::SmartScopedWriter<true> Writer(*GCLock);
277  if (!GCNamePool)
278    GCNamePool = new StringPool();
279  if (!GCNames)
280    GCNames = new DenseMap<const Function*,PooledStringPtr>();
281  (*GCNames)[this] = GCNamePool->intern(Str);
282}
283
284void Function::clearGC() {
285  sys::SmartScopedWriter<true> Writer(*GCLock);
286  if (GCNames) {
287    GCNames->erase(this);
288    if (GCNames->empty()) {
289      delete GCNames;
290      GCNames = 0;
291      if (GCNamePool->empty()) {
292        delete GCNamePool;
293        GCNamePool = 0;
294      }
295    }
296  }
297}
298
299/// copyAttributesFrom - copy all additional attributes (those not needed to
300/// create a Function) from the Function Src to this one.
301void Function::copyAttributesFrom(const GlobalValue *Src) {
302  assert(isa<Function>(Src) && "Expected a Function!");
303  GlobalValue::copyAttributesFrom(Src);
304  const Function *SrcF = cast<Function>(Src);
305  setCallingConv(SrcF->getCallingConv());
306  setAttributes(SrcF->getAttributes());
307  if (SrcF->hasGC())
308    setGC(SrcF->getGC());
309  else
310    clearGC();
311}
312
313/// initIntrinsicID - This method returns the ID number of the specified
314/// function, or Intrinsic::not_intrinsic if the function is not an
315/// intrinsic, or if the pointer is null.  This value is always defined to be
316/// zero to allow easy checking for whether a function is intrinsic or not.  The
317/// particular intrinsic functions which correspond to this value are defined in
318/// llvm/Intrinsics.h.
319///
320unsigned Function::initIntrinsicID() const {
321  const ValueName *ValName = this->getValueName();
322  if (!ValName)
323    return 0;
324  unsigned Len = ValName->getKeyLength();
325  const char *Name = ValName->getKeyData();
326
327  if (Len < 5 || Name[4] != '.' || Name[0] != 'l' || Name[1] != 'l'
328      || Name[2] != 'v' || Name[3] != 'm')
329    return 0;  // All intrinsics start with 'llvm.'
330
331#define GET_FUNCTION_RECOGNIZER
332#include "llvm/Intrinsics.gen"
333#undef GET_FUNCTION_RECOGNIZER
334  return 0;
335}
336
337std::string Intrinsic::getName(ID id, ArrayRef<Type*> Tys) {
338  assert(id < num_intrinsics && "Invalid intrinsic ID!");
339  static const char * const Table[] = {
340    "not_intrinsic",
341#define GET_INTRINSIC_NAME_TABLE
342#include "llvm/Intrinsics.gen"
343#undef GET_INTRINSIC_NAME_TABLE
344  };
345  if (Tys.empty())
346    return Table[id];
347  std::string Result(Table[id]);
348  for (unsigned i = 0; i < Tys.size(); ++i) {
349    if (PointerType* PTyp = dyn_cast<PointerType>(Tys[i])) {
350      Result += ".p" + llvm::utostr(PTyp->getAddressSpace()) +
351                EVT::getEVT(PTyp->getElementType()).getEVTString();
352    }
353    else if (Tys[i])
354      Result += "." + EVT::getEVT(Tys[i]).getEVTString();
355  }
356  return Result;
357}
358
359FunctionType *Intrinsic::getType(LLVMContext &Context,
360                                       ID id, ArrayRef<Type*> Tys) {
361  Type *ResultTy = NULL;
362  std::vector<Type*> ArgTys;
363  bool IsVarArg = false;
364
365#define GET_INTRINSIC_GENERATOR
366#include "llvm/Intrinsics.gen"
367#undef GET_INTRINSIC_GENERATOR
368
369  return FunctionType::get(ResultTy, ArgTys, IsVarArg);
370}
371
372bool Intrinsic::isOverloaded(ID id) {
373  static const bool OTable[] = {
374    false,
375#define GET_INTRINSIC_OVERLOAD_TABLE
376#include "llvm/Intrinsics.gen"
377#undef GET_INTRINSIC_OVERLOAD_TABLE
378  };
379  return OTable[id];
380}
381
382/// This defines the "Intrinsic::getAttributes(ID id)" method.
383#define GET_INTRINSIC_ATTRIBUTES
384#include "llvm/Intrinsics.gen"
385#undef GET_INTRINSIC_ATTRIBUTES
386
387Function *Intrinsic::getDeclaration(Module *M, ID id, ArrayRef<Type*> Tys) {
388  // There can never be multiple globals with the same name of different types,
389  // because intrinsics must be a specific type.
390  return
391    cast<Function>(M->getOrInsertFunction(getName(id, Tys),
392                                          getType(M->getContext(), id, Tys)));
393}
394
395// This defines the "Intrinsic::getIntrinsicForGCCBuiltin()" method.
396#define GET_LLVM_INTRINSIC_FOR_GCC_BUILTIN
397#include "llvm/Intrinsics.gen"
398#undef GET_LLVM_INTRINSIC_FOR_GCC_BUILTIN
399
400/// hasAddressTaken - returns true if there are any uses of this function
401/// other than direct calls or invokes to it.
402bool Function::hasAddressTaken(const User* *PutOffender) const {
403  for (Value::const_use_iterator I = use_begin(), E = use_end(); I != E; ++I) {
404    const User *U = *I;
405    if (!isa<CallInst>(U) && !isa<InvokeInst>(U))
406      return PutOffender ? (*PutOffender = U, true) : true;
407    ImmutableCallSite CS(cast<Instruction>(U));
408    if (!CS.isCallee(I))
409      return PutOffender ? (*PutOffender = U, true) : true;
410  }
411  return false;
412}
413
414/// callsFunctionThatReturnsTwice - Return true if the function has a call to
415/// setjmp or other function that gcc recognizes as "returning twice".
416///
417/// FIXME: Remove after <rdar://problem/8031714> is fixed.
418/// FIXME: Is the above FIXME valid?
419bool Function::callsFunctionThatReturnsTwice() const {
420  static const char *const ReturnsTwiceFns[] = {
421    "_setjmp",
422    "setjmp",
423    "sigsetjmp",
424    "setjmp_syscall",
425    "savectx",
426    "qsetjmp",
427    "vfork",
428    "getcontext"
429  };
430
431  for (const_inst_iterator I = inst_begin(this), E = inst_end(this); I != E;
432       ++I) {
433    const CallInst* callInst = dyn_cast<CallInst>(&*I);
434    if (!callInst)
435      continue;
436    if (callInst->canReturnTwice())
437      return true;
438
439    // check for known function names.
440    // FIXME: move this to clang.
441    Function *F = callInst->getCalledFunction();
442    if (!F)
443      continue;
444    StringRef Name = F->getName();
445    for (unsigned J = 0, e = array_lengthof(ReturnsTwiceFns); J != e; ++J) {
446      if (Name == ReturnsTwiceFns[J])
447        return true;
448    }
449  }
450
451  return false;
452}
453
454// vim: sw=2 ai
455