CGExprConstant.cpp revision 9408c45009b417e758749b3d95cdfb87dcb68ea9 
1//===--- CGExprConstant.cpp - Emit LLVM Code from Constant Expressions ----===//
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 contains code to emit Constant Expr nodes as LLVM code.
11//
12//===----------------------------------------------------------------------===//
13
14#include "CodeGenFunction.h"
15#include "CodeGenModule.h"
16#include "CGObjCRuntime.h"
17#include "clang/AST/APValue.h"
18#include "clang/AST/ASTContext.h"
19#include "clang/AST/StmtVisitor.h"
20#include "llvm/Constants.h"
21#include "llvm/Function.h"
22#include "llvm/GlobalVariable.h"
23#include "llvm/Support/Compiler.h"
24#include "llvm/Target/TargetData.h"
25using namespace clang;
26using namespace CodeGen;
27
28namespace  {
29class VISIBILITY_HIDDEN ConstExprEmitter :
30  public StmtVisitor<ConstExprEmitter, llvm::Constant*> {
31  CodeGenModule &CGM;
32  CodeGenFunction *CGF;
33public:
34  ConstExprEmitter(CodeGenModule &cgm, CodeGenFunction *cgf)
35    : CGM(cgm), CGF(cgf) {
36  }
37
38  //===--------------------------------------------------------------------===//
39  //                            Visitor Methods
40  //===--------------------------------------------------------------------===//
41
42  llvm::Constant *VisitStmt(Stmt *S) {
43    return 0;
44  }
45
46  llvm::Constant *VisitParenExpr(ParenExpr *PE) {
47    return Visit(PE->getSubExpr());
48  }
49
50  llvm::Constant *VisitCompoundLiteralExpr(CompoundLiteralExpr *E) {
51    return Visit(E->getInitializer());
52  }
53
54  llvm::Constant *VisitCastExpr(CastExpr* E) {
55    // GCC cast to union extension
56    if (E->getType()->isUnionType()) {
57      const llvm::Type *Ty = ConvertType(E->getType());
58      Expr *SubExpr = E->getSubExpr();
59      return EmitUnion(CGM.EmitConstantExpr(SubExpr, SubExpr->getType(), CGF),
60                       Ty);
61    }
62    // Explicit and implicit no-op casts
63    QualType Ty = E->getType(), SubTy = E->getSubExpr()->getType();
64    if (CGM.getContext().hasSameUnqualifiedType(Ty, SubTy)) {
65      return Visit(E->getSubExpr());
66    }
67    return 0;
68  }
69
70  llvm::Constant *VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) {
71    return Visit(DAE->getExpr());
72  }
73
74  llvm::Constant *EmitArrayInitialization(InitListExpr *ILE) {
75    std::vector<llvm::Constant*> Elts;
76    const llvm::ArrayType *AType =
77        cast<llvm::ArrayType>(ConvertType(ILE->getType()));
78    unsigned NumInitElements = ILE->getNumInits();
79    // FIXME: Check for wide strings
80    // FIXME: Check for NumInitElements exactly equal to 1??
81    if (NumInitElements > 0 &&
82        (isa<StringLiteral>(ILE->getInit(0)) ||
83         isa<ObjCEncodeExpr>(ILE->getInit(0))) &&
84        ILE->getType()->getArrayElementTypeNoTypeQual()->isCharType())
85      return Visit(ILE->getInit(0));
86    const llvm::Type *ElemTy = AType->getElementType();
87    unsigned NumElements = AType->getNumElements();
88
89    // Initialising an array requires us to automatically
90    // initialise any elements that have not been initialised explicitly
91    unsigned NumInitableElts = std::min(NumInitElements, NumElements);
92
93    // Copy initializer elements.
94    unsigned i = 0;
95    bool RewriteType = false;
96    for (; i < NumInitableElts; ++i) {
97      Expr *Init = ILE->getInit(i);
98      llvm::Constant *C = CGM.EmitConstantExpr(Init, Init->getType(), CGF);
99      if (!C)
100        return 0;
101      RewriteType |= (C->getType() != ElemTy);
102      Elts.push_back(C);
103    }
104
105    // Initialize remaining array elements.
106    // FIXME: This doesn't handle member pointers correctly!
107    for (; i < NumElements; ++i)
108      Elts.push_back(llvm::Constant::getNullValue(ElemTy));
109
110    if (RewriteType) {
111      // FIXME: Try to avoid packing the array
112      std::vector<const llvm::Type*> Types;
113      for (unsigned i = 0; i < Elts.size(); ++i)
114        Types.push_back(Elts[i]->getType());
115      const llvm::StructType *SType = llvm::StructType::get(Types, true);
116      return llvm::ConstantStruct::get(SType, Elts);
117    }
118
119    return llvm::ConstantArray::get(AType, Elts);
120  }
121
122  void InsertBitfieldIntoStruct(std::vector<llvm::Constant*>& Elts,
123                                FieldDecl* Field, Expr* E) {
124    // Calculate the value to insert
125    llvm::Constant *C = CGM.EmitConstantExpr(E, Field->getType(), CGF);
126    if (!C)
127      return;
128
129    llvm::ConstantInt *CI = dyn_cast<llvm::ConstantInt>(C);
130    if (!CI) {
131      CGM.ErrorUnsupported(E, "bitfield initialization");
132      return;
133    }
134    llvm::APInt V = CI->getValue();
135
136    // Calculate information about the relevant field
137    const llvm::Type* Ty = CI->getType();
138    const llvm::TargetData &TD = CGM.getTypes().getTargetData();
139    unsigned size = TD.getTypeAllocSizeInBits(Ty);
140    unsigned fieldOffset = CGM.getTypes().getLLVMFieldNo(Field) * size;
141    CodeGenTypes::BitFieldInfo bitFieldInfo =
142        CGM.getTypes().getBitFieldInfo(Field);
143    fieldOffset += bitFieldInfo.Begin;
144
145    // Find where to start the insertion
146    // FIXME: This is O(n^2) in the number of bit-fields!
147    // FIXME: This won't work if the struct isn't completely packed!
148    unsigned offset = 0, i = 0;
149    while (offset < (fieldOffset & -8))
150      offset += TD.getTypeAllocSizeInBits(Elts[i++]->getType());
151
152    // Advance over 0 sized elements (must terminate in bounds since
153    // the bitfield must have a size).
154    while (TD.getTypeAllocSizeInBits(Elts[i]->getType()) == 0)
155      ++i;
156
157    // Promote the size of V if necessary
158    // FIXME: This should never occur, but currently it can because
159    // initializer constants are cast to bool, and because clang is
160    // not enforcing bitfield width limits.
161    if (bitFieldInfo.Size > V.getBitWidth())
162      V.zext(bitFieldInfo.Size);
163
164    // Insert the bits into the struct
165    // FIXME: This algorthm is only correct on X86!
166    // FIXME: THis algorthm assumes bit-fields only have byte-size elements!
167    unsigned bitsToInsert = bitFieldInfo.Size;
168    unsigned curBits = std::min(8 - (fieldOffset & 7), bitsToInsert);
169    unsigned byte = V.getLoBits(curBits).getZExtValue() << (fieldOffset & 7);
170    do {
171      llvm::Constant* byteC = llvm::ConstantInt::get(llvm::Type::Int8Ty, byte);
172      Elts[i] = llvm::ConstantExpr::getOr(Elts[i], byteC);
173      ++i;
174      V = V.lshr(curBits);
175      bitsToInsert -= curBits;
176
177      if (!bitsToInsert)
178        break;
179
180      curBits = bitsToInsert > 8 ? 8 : bitsToInsert;
181      byte = V.getLoBits(curBits).getZExtValue();
182    } while (true);
183  }
184
185  llvm::Constant *EmitStructInitialization(InitListExpr *ILE) {
186    const llvm::StructType *SType =
187        cast<llvm::StructType>(ConvertType(ILE->getType()));
188    RecordDecl *RD = ILE->getType()->getAsRecordType()->getDecl();
189    std::vector<llvm::Constant*> Elts;
190
191    // Initialize the whole structure to zero.
192    // FIXME: This doesn't handle member pointers correctly!
193    for (unsigned i = 0; i < SType->getNumElements(); ++i) {
194      const llvm::Type *FieldTy = SType->getElementType(i);
195      Elts.push_back(llvm::Constant::getNullValue(FieldTy));
196    }
197
198    // Copy initializer elements. Skip padding fields.
199    unsigned EltNo = 0;  // Element no in ILE
200    int FieldNo = 0; // Field no in RecordDecl
201    bool RewriteType = false;
202    for (RecordDecl::field_iterator Field = RD->field_begin(CGM.getContext()),
203                                 FieldEnd = RD->field_end(CGM.getContext());
204         EltNo < ILE->getNumInits() && Field != FieldEnd; ++Field) {
205      FieldNo++;
206      if (!Field->getIdentifier())
207        continue;
208
209      if (Field->isBitField()) {
210        InsertBitfieldIntoStruct(Elts, *Field, ILE->getInit(EltNo));
211      } else {
212        unsigned FieldNo = CGM.getTypes().getLLVMFieldNo(*Field);
213        llvm::Constant *C = CGM.EmitConstantExpr(ILE->getInit(EltNo),
214                                                 Field->getType(), CGF);
215        if (!C) return 0;
216        RewriteType |= (C->getType() != Elts[FieldNo]->getType());
217        Elts[FieldNo] = C;
218      }
219      EltNo++;
220    }
221
222    if (RewriteType) {
223      // FIXME: Make this work for non-packed structs
224      assert(SType->isPacked() && "Cannot recreate unpacked structs");
225      std::vector<const llvm::Type*> Types;
226      for (unsigned i = 0; i < Elts.size(); ++i)
227        Types.push_back(Elts[i]->getType());
228      SType = llvm::StructType::get(Types, true);
229    }
230
231    return llvm::ConstantStruct::get(SType, Elts);
232  }
233
234  llvm::Constant *EmitUnion(llvm::Constant *C, const llvm::Type *Ty) {
235    if (!C)
236      return 0;
237
238    // Build a struct with the union sub-element as the first member,
239    // and padded to the appropriate size
240    std::vector<llvm::Constant*> Elts;
241    std::vector<const llvm::Type*> Types;
242    Elts.push_back(C);
243    Types.push_back(C->getType());
244    unsigned CurSize = CGM.getTargetData().getTypeAllocSize(C->getType());
245    unsigned TotalSize = CGM.getTargetData().getTypeAllocSize(Ty);
246    while (CurSize < TotalSize) {
247      Elts.push_back(llvm::Constant::getNullValue(llvm::Type::Int8Ty));
248      Types.push_back(llvm::Type::Int8Ty);
249      CurSize++;
250    }
251
252    // This always generates a packed struct
253    // FIXME: Try to generate an unpacked struct when we can
254    llvm::StructType* STy = llvm::StructType::get(Types, true);
255    return llvm::ConstantStruct::get(STy, Elts);
256  }
257
258  llvm::Constant *EmitUnionInitialization(InitListExpr *ILE) {
259    const llvm::Type *Ty = ConvertType(ILE->getType());
260
261    FieldDecl* curField = ILE->getInitializedFieldInUnion();
262    if (!curField) {
263      // There's no field to initialize, so value-initialize the union.
264#ifndef NDEBUG
265      // Make sure that it's really an empty and not a failure of
266      // semantic analysis.
267      RecordDecl *RD = ILE->getType()->getAsRecordType()->getDecl();
268      for (RecordDecl::field_iterator Field = RD->field_begin(CGM.getContext()),
269                                   FieldEnd = RD->field_end(CGM.getContext());
270           Field != FieldEnd; ++Field)
271        assert(Field->isUnnamedBitfield() && "Only unnamed bitfields allowed");
272#endif
273      return llvm::Constant::getNullValue(Ty);
274    }
275
276    if (curField->isBitField()) {
277      // Create a dummy struct for bit-field insertion
278      unsigned NumElts = CGM.getTargetData().getTypeAllocSize(Ty);
279      llvm::Constant* NV = llvm::Constant::getNullValue(llvm::Type::Int8Ty);
280      std::vector<llvm::Constant*> Elts(NumElts, NV);
281
282      InsertBitfieldIntoStruct(Elts, curField, ILE->getInit(0));
283      const llvm::ArrayType *RetTy =
284          llvm::ArrayType::get(NV->getType(), NumElts);
285      return llvm::ConstantArray::get(RetTy, Elts);
286    }
287
288    llvm::Constant *InitElem;
289    if (ILE->getNumInits() > 0) {
290      Expr *Init = ILE->getInit(0);
291      InitElem = CGM.EmitConstantExpr(Init, Init->getType(), CGF);
292    } else {
293      InitElem = CGM.EmitNullConstant(curField->getType());
294    }
295    return EmitUnion(InitElem, Ty);
296  }
297
298  llvm::Constant *EmitVectorInitialization(InitListExpr *ILE) {
299    const llvm::VectorType *VType =
300        cast<llvm::VectorType>(ConvertType(ILE->getType()));
301    const llvm::Type *ElemTy = VType->getElementType();
302    std::vector<llvm::Constant*> Elts;
303    unsigned NumElements = VType->getNumElements();
304    unsigned NumInitElements = ILE->getNumInits();
305
306    unsigned NumInitableElts = std::min(NumInitElements, NumElements);
307
308    // Copy initializer elements.
309    unsigned i = 0;
310    for (; i < NumInitableElts; ++i) {
311      Expr *Init = ILE->getInit(i);
312      llvm::Constant *C = CGM.EmitConstantExpr(Init, Init->getType(), CGF);
313      if (!C)
314        return 0;
315      Elts.push_back(C);
316    }
317
318    for (; i < NumElements; ++i)
319      Elts.push_back(llvm::Constant::getNullValue(ElemTy));
320
321    return llvm::ConstantVector::get(VType, Elts);
322  }
323
324  llvm::Constant *VisitImplicitValueInitExpr(ImplicitValueInitExpr* E) {
325    return CGM.EmitNullConstant(E->getType());
326  }
327
328  llvm::Constant *VisitInitListExpr(InitListExpr *ILE) {
329    if (ILE->getType()->isScalarType()) {
330      // We have a scalar in braces. Just use the first element.
331      if (ILE->getNumInits() > 0) {
332        Expr *Init = ILE->getInit(0);
333        return CGM.EmitConstantExpr(Init, Init->getType(), CGF);
334      }
335      return CGM.EmitNullConstant(ILE->getType());
336    }
337
338    if (ILE->getType()->isArrayType())
339      return EmitArrayInitialization(ILE);
340
341    if (ILE->getType()->isStructureType())
342      return EmitStructInitialization(ILE);
343
344    if (ILE->getType()->isUnionType())
345      return EmitUnionInitialization(ILE);
346
347    if (ILE->getType()->isVectorType())
348      return EmitVectorInitialization(ILE);
349
350    assert(0 && "Unable to handle InitListExpr");
351    // Get rid of control reaches end of void function warning.
352    // Not reached.
353    return 0;
354  }
355
356  llvm::Constant *VisitStringLiteral(StringLiteral *E) {
357    assert(!E->getType()->isPointerType() && "Strings are always arrays");
358
359    // This must be a string initializing an array in a static initializer.
360    // Don't emit it as the address of the string, emit the string data itself
361    // as an inline array.
362    return llvm::ConstantArray::get(CGM.GetStringForStringLiteral(E), false);
363  }
364
365  llvm::Constant *VisitObjCEncodeExpr(ObjCEncodeExpr *E) {
366    // This must be an @encode initializing an array in a static initializer.
367    // Don't emit it as the address of the string, emit the string data itself
368    // as an inline array.
369    std::string Str;
370    CGM.getContext().getObjCEncodingForType(E->getEncodedType(), Str);
371    const ConstantArrayType *CAT = cast<ConstantArrayType>(E->getType());
372
373    // Resize the string to the right size, adding zeros at the end, or
374    // truncating as needed.
375    Str.resize(CAT->getSize().getZExtValue(), '\0');
376    return llvm::ConstantArray::get(Str, false);
377  }
378
379  llvm::Constant *VisitUnaryExtension(const UnaryOperator *E) {
380    return Visit(E->getSubExpr());
381  }
382
383  // Utility methods
384  const llvm::Type *ConvertType(QualType T) {
385    return CGM.getTypes().ConvertType(T);
386  }
387
388public:
389  llvm::Constant *EmitLValue(Expr *E) {
390    switch (E->getStmtClass()) {
391    default: break;
392    case Expr::CompoundLiteralExprClass: {
393      // Note that due to the nature of compound literals, this is guaranteed
394      // to be the only use of the variable, so we just generate it here.
395      CompoundLiteralExpr *CLE = cast<CompoundLiteralExpr>(E);
396      llvm::Constant* C = Visit(CLE->getInitializer());
397      // FIXME: "Leaked" on failure.
398      if (C)
399        C = new llvm::GlobalVariable(C->getType(),
400                                     E->getType().isConstQualified(),
401                                     llvm::GlobalValue::InternalLinkage,
402                                     C, ".compoundliteral", &CGM.getModule());
403      return C;
404    }
405    case Expr::DeclRefExprClass:
406    case Expr::QualifiedDeclRefExprClass: {
407      NamedDecl *Decl = cast<DeclRefExpr>(E)->getDecl();
408      if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(Decl))
409        return CGM.GetAddrOfFunction(FD);
410      if (const VarDecl* VD = dyn_cast<VarDecl>(Decl)) {
411        // We can never refer to a variable with local storage.
412        if (!VD->hasLocalStorage()) {
413          if (VD->isFileVarDecl() || VD->hasExternalStorage())
414            return CGM.GetAddrOfGlobalVar(VD);
415          else if (VD->isBlockVarDecl()) {
416            assert(CGF && "Can't access static local vars without CGF");
417            return CGF->GetAddrOfStaticLocalVar(VD);
418          }
419        }
420      }
421      break;
422    }
423    case Expr::StringLiteralClass:
424      return CGM.GetAddrOfConstantStringFromLiteral(cast<StringLiteral>(E));
425    case Expr::ObjCEncodeExprClass:
426      return CGM.GetAddrOfConstantStringFromObjCEncode(cast<ObjCEncodeExpr>(E));
427    case Expr::ObjCStringLiteralClass: {
428      ObjCStringLiteral* SL = cast<ObjCStringLiteral>(E);
429      llvm::Constant *C = CGM.getObjCRuntime().GenerateConstantString(SL);
430      return llvm::ConstantExpr::getBitCast(C, ConvertType(E->getType()));
431    }
432    case Expr::PredefinedExprClass: {
433      // __func__/__FUNCTION__ -> "".  __PRETTY_FUNCTION__ -> "top level".
434      std::string Str;
435      if (cast<PredefinedExpr>(E)->getIdentType() ==
436          PredefinedExpr::PrettyFunction)
437        Str = "top level";
438
439      return CGM.GetAddrOfConstantCString(Str, ".tmp");
440    }
441    case Expr::AddrLabelExprClass: {
442      assert(CGF && "Invalid address of label expression outside function.");
443      unsigned id = CGF->GetIDForAddrOfLabel(cast<AddrLabelExpr>(E)->getLabel());
444      llvm::Constant *C = llvm::ConstantInt::get(llvm::Type::Int32Ty, id);
445      return llvm::ConstantExpr::getIntToPtr(C, ConvertType(E->getType()));
446    }
447    case Expr::CallExprClass: {
448      CallExpr* CE = cast<CallExpr>(E);
449      if (CE->isBuiltinCall(CGM.getContext()) !=
450            Builtin::BI__builtin___CFStringMakeConstantString)
451        break;
452      const Expr *Arg = CE->getArg(0)->IgnoreParenCasts();
453      const StringLiteral *Literal = cast<StringLiteral>(Arg);
454      // FIXME: need to deal with UCN conversion issues.
455      return CGM.GetAddrOfConstantCFString(Literal);
456    }
457    case Expr::BlockExprClass: {
458      std::string FunctionName;
459      if (CGF)
460        FunctionName = CGF->CurFn->getName();
461      else
462        FunctionName = "global";
463
464      return CGM.GetAddrOfGlobalBlock(cast<BlockExpr>(E), FunctionName.c_str());
465    }
466    }
467
468    return 0;
469  }
470};
471
472}  // end anonymous namespace.
473
474llvm::Constant *CodeGenModule::EmitConstantExpr(const Expr *E,
475                                                QualType DestType,
476                                                CodeGenFunction *CGF) {
477  Expr::EvalResult Result;
478
479  bool Success = false;
480
481  if (DestType->isReferenceType()) {
482    // If the destination type is a reference type, we need to evaluate it
483    // as an lvalue.
484    if (E->EvaluateAsLValue(Result, Context)) {
485      if (const Expr *LVBase = Result.Val.getLValueBase()) {
486        if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(LVBase)) {
487          const ValueDecl *VD = cast<ValueDecl>(DRE->getDecl());
488
489          // We can only initialize a reference with an lvalue if the lvalue
490          // is not a reference itself.
491          Success = !VD->getType()->isReferenceType();
492        }
493      }
494    }
495  } else
496    Success = E->Evaluate(Result, Context);
497
498  if (Success) {
499    assert(!Result.HasSideEffects &&
500           "Constant expr should not have any side effects!");
501    switch (Result.Val.getKind()) {
502    case APValue::Uninitialized:
503      assert(0 && "Constant expressions should be initialized.");
504      return 0;
505    case APValue::LValue: {
506      const llvm::Type *DestTy = getTypes().ConvertTypeForMem(DestType);
507      llvm::Constant *Offset =
508        llvm::ConstantInt::get(llvm::Type::Int64Ty,
509                               Result.Val.getLValueOffset());
510
511      llvm::Constant *C;
512      if (const Expr *LVBase = Result.Val.getLValueBase()) {
513        C = ConstExprEmitter(*this, CGF).EmitLValue(const_cast<Expr*>(LVBase));
514
515        // Apply offset if necessary.
516        if (!Offset->isNullValue()) {
517          const llvm::Type *Type =
518            llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
519          llvm::Constant *Casted = llvm::ConstantExpr::getBitCast(C, Type);
520          Casted = llvm::ConstantExpr::getGetElementPtr(Casted, &Offset, 1);
521          C = llvm::ConstantExpr::getBitCast(Casted, C->getType());
522        }
523
524        // Convert to the appropriate type; this could be an lvalue for
525        // an integer.
526        if (isa<llvm::PointerType>(DestTy))
527          return llvm::ConstantExpr::getBitCast(C, DestTy);
528
529        return llvm::ConstantExpr::getPtrToInt(C, DestTy);
530      } else {
531        C = Offset;
532
533        // Convert to the appropriate type; this could be an lvalue for
534        // an integer.
535        if (isa<llvm::PointerType>(DestTy))
536          return llvm::ConstantExpr::getIntToPtr(C, DestTy);
537
538        // If the types don't match this should only be a truncate.
539        if (C->getType() != DestTy)
540          return llvm::ConstantExpr::getTrunc(C, DestTy);
541
542        return C;
543      }
544    }
545    case APValue::Int: {
546      llvm::Constant *C = llvm::ConstantInt::get(Result.Val.getInt());
547
548      if (C->getType() == llvm::Type::Int1Ty) {
549        const llvm::Type *BoolTy = getTypes().ConvertTypeForMem(E->getType());
550        C = llvm::ConstantExpr::getZExt(C, BoolTy);
551      }
552      return C;
553    }
554    case APValue::ComplexInt: {
555      llvm::Constant *Complex[2];
556
557      Complex[0] = llvm::ConstantInt::get(Result.Val.getComplexIntReal());
558      Complex[1] = llvm::ConstantInt::get(Result.Val.getComplexIntImag());
559
560      return llvm::ConstantStruct::get(Complex, 2);
561    }
562    case APValue::Float:
563      return llvm::ConstantFP::get(Result.Val.getFloat());
564    case APValue::ComplexFloat: {
565      llvm::Constant *Complex[2];
566
567      Complex[0] = llvm::ConstantFP::get(Result.Val.getComplexFloatReal());
568      Complex[1] = llvm::ConstantFP::get(Result.Val.getComplexFloatImag());
569
570      return llvm::ConstantStruct::get(Complex, 2);
571    }
572    case APValue::Vector: {
573      llvm::SmallVector<llvm::Constant *, 4> Inits;
574      unsigned NumElts = Result.Val.getVectorLength();
575
576      for (unsigned i = 0; i != NumElts; ++i) {
577        APValue &Elt = Result.Val.getVectorElt(i);
578        if (Elt.isInt())
579          Inits.push_back(llvm::ConstantInt::get(Elt.getInt()));
580        else
581          Inits.push_back(llvm::ConstantFP::get(Elt.getFloat()));
582      }
583      return llvm::ConstantVector::get(&Inits[0], Inits.size());
584    }
585    }
586  }
587
588  llvm::Constant* C = ConstExprEmitter(*this, CGF).Visit(const_cast<Expr*>(E));
589  if (C && C->getType() == llvm::Type::Int1Ty) {
590    const llvm::Type *BoolTy = getTypes().ConvertTypeForMem(E->getType());
591    C = llvm::ConstantExpr::getZExt(C, BoolTy);
592  }
593  return C;
594}
595
596llvm::Constant *CodeGenModule::EmitNullConstant(QualType T) {
597  // Always return an LLVM null constant for now; this will change when we
598  // get support for IRGen of member pointers.
599  return llvm::Constant::getNullValue(getTypes().ConvertType(T));
600}
601