1 //===--- CGExprComplex.cpp - Emit LLVM Code for Complex Exprs -------------===//
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 Expr nodes with complex types as LLVM code.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "CodeGenFunction.h"
15 #include "CodeGenModule.h"
16 #include "clang/AST/ASTContext.h"
17 #include "clang/AST/StmtVisitor.h"
18 #include "llvm/Constants.h"
19 #include "llvm/Function.h"
20 #include "llvm/ADT/SmallString.h"
21 #include "llvm/Support/Compiler.h"
22 using namespace clang;
23 using namespace CodeGen;
24 
25 //===----------------------------------------------------------------------===//
26 //                        Complex Expression Emitter
27 //===----------------------------------------------------------------------===//
28 
29 typedef CodeGenFunction::ComplexPairTy ComplexPairTy;
30 
31 namespace  {
32 class VISIBILITY_HIDDEN ComplexExprEmitter
33   : public StmtVisitor<ComplexExprEmitter, ComplexPairTy> {
34   CodeGenFunction &CGF;
35   CGBuilderTy &Builder;
36 public:
37   ComplexExprEmitter(CodeGenFunction &cgf) : CGF(cgf), Builder(CGF.Builder) {
38   }
39 
40 
41   //===--------------------------------------------------------------------===//
42   //                               Utilities
43   //===--------------------------------------------------------------------===//
44 
45   /// EmitLoadOfLValue - Given an expression with complex type that represents a
46   /// value l-value, this method emits the address of the l-value, then loads
47   /// and returns the result.
48   ComplexPairTy EmitLoadOfLValue(const Expr *E) {
49     LValue LV = CGF.EmitLValue(E);
50     // FIXME: Volatile
51     return EmitLoadOfComplex(LV.getAddress(), false);
52   }
53 
54   /// EmitLoadOfComplex - Given a pointer to a complex value, emit code to load
55   /// the real and imaginary pieces.
56   ComplexPairTy EmitLoadOfComplex(llvm::Value *SrcPtr, bool isVolatile);
57 
58   /// EmitStoreOfComplex - Store the specified real/imag parts into the
59   /// specified value pointer.
60   void EmitStoreOfComplex(ComplexPairTy Val, llvm::Value *ResPtr, bool isVol);
61 
62   /// EmitComplexToComplexCast - Emit a cast from complex value Val to DestType.
63   ComplexPairTy EmitComplexToComplexCast(ComplexPairTy Val, QualType SrcType,
64                                          QualType DestType);
65 
66   //===--------------------------------------------------------------------===//
67   //                            Visitor Methods
68   //===--------------------------------------------------------------------===//
69 
70   ComplexPairTy VisitStmt(Stmt *S) {
71     S->dump(CGF.getContext().getSourceManager());
72     assert(0 && "Stmt can't have complex result type!");
73     return ComplexPairTy();
74   }
75   ComplexPairTy VisitExpr(Expr *S);
76   ComplexPairTy VisitParenExpr(ParenExpr *PE) { return Visit(PE->getSubExpr());}
77   ComplexPairTy VisitImaginaryLiteral(const ImaginaryLiteral *IL);
78 
79   // l-values.
80   ComplexPairTy VisitDeclRefExpr(const Expr *E) { return EmitLoadOfLValue(E); }
81   ComplexPairTy VisitArraySubscriptExpr(Expr *E) { return EmitLoadOfLValue(E); }
82   ComplexPairTy VisitMemberExpr(const Expr *E) { return EmitLoadOfLValue(E); }
83 
84   // FIXME: CompoundLiteralExpr
85 
86   ComplexPairTy EmitCast(Expr *Op, QualType DestTy);
87   ComplexPairTy VisitImplicitCastExpr(ImplicitCastExpr *E) {
88     // Unlike for scalars, we don't have to worry about function->ptr demotion
89     // here.
90     return EmitCast(E->getSubExpr(), E->getType());
91   }
92   ComplexPairTy VisitCastExpr(CastExpr *E) {
93     return EmitCast(E->getSubExpr(), E->getType());
94   }
95   ComplexPairTy VisitCallExpr(const CallExpr *E);
96   ComplexPairTy VisitStmtExpr(const StmtExpr *E);
97   ComplexPairTy VisitOverloadExpr(const OverloadExpr *OE);
98 
99   // Operators.
100   ComplexPairTy VisitPrePostIncDec(const UnaryOperator *E,
101                                    bool isInc, bool isPre);
102   ComplexPairTy VisitUnaryPostDec(const UnaryOperator *E) {
103     return VisitPrePostIncDec(E, false, false);
104   }
105   ComplexPairTy VisitUnaryPostInc(const UnaryOperator *E) {
106     return VisitPrePostIncDec(E, true, false);
107   }
108   ComplexPairTy VisitUnaryPreDec(const UnaryOperator *E) {
109     return VisitPrePostIncDec(E, false, true);
110   }
111   ComplexPairTy VisitUnaryPreInc(const UnaryOperator *E) {
112     return VisitPrePostIncDec(E, true, true);
113   }
114   ComplexPairTy VisitUnaryDeref(const Expr *E) { return EmitLoadOfLValue(E); }
115   ComplexPairTy VisitUnaryPlus     (const UnaryOperator *E) {
116     return Visit(E->getSubExpr());
117   }
118   ComplexPairTy VisitUnaryMinus    (const UnaryOperator *E);
119   ComplexPairTy VisitUnaryNot      (const UnaryOperator *E);
120   // LNot,Real,Imag never return complex.
121   ComplexPairTy VisitUnaryExtension(const UnaryOperator *E) {
122     return Visit(E->getSubExpr());
123   }
124   ComplexPairTy VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) {
125     return Visit(DAE->getExpr());
126   }
127   ComplexPairTy VisitCXXZeroInitValueExpr(CXXZeroInitValueExpr *E) {
128     assert(E->getType()->isAnyComplexType() && "Expected complex type!");
129     QualType Elem = E->getType()->getAsComplexType()->getElementType();
130     llvm::Constant *Null = llvm::Constant::getNullValue(CGF.ConvertType(Elem));
131     return ComplexPairTy(Null, Null);
132   }
133 
134   struct BinOpInfo {
135     ComplexPairTy LHS;
136     ComplexPairTy RHS;
137     QualType Ty;  // Computation Type.
138   };
139 
140   BinOpInfo EmitBinOps(const BinaryOperator *E);
141   ComplexPairTy EmitCompoundAssign(const CompoundAssignOperator *E,
142                                    ComplexPairTy (ComplexExprEmitter::*Func)
143                                    (const BinOpInfo &));
144 
145   ComplexPairTy EmitBinAdd(const BinOpInfo &Op);
146   ComplexPairTy EmitBinSub(const BinOpInfo &Op);
147   ComplexPairTy EmitBinMul(const BinOpInfo &Op);
148   ComplexPairTy EmitBinDiv(const BinOpInfo &Op);
149 
150   ComplexPairTy VisitBinMul(const BinaryOperator *E) {
151     return EmitBinMul(EmitBinOps(E));
152   }
153   ComplexPairTy VisitBinAdd(const BinaryOperator *E) {
154     return EmitBinAdd(EmitBinOps(E));
155   }
156   ComplexPairTy VisitBinSub(const BinaryOperator *E) {
157     return EmitBinSub(EmitBinOps(E));
158   }
159   ComplexPairTy VisitBinDiv(const BinaryOperator *E) {
160     return EmitBinDiv(EmitBinOps(E));
161   }
162 
163   // Compound assignments.
164   ComplexPairTy VisitBinAddAssign(const CompoundAssignOperator *E) {
165     return EmitCompoundAssign(E, &ComplexExprEmitter::EmitBinAdd);
166   }
167   ComplexPairTy VisitBinSubAssign(const CompoundAssignOperator *E) {
168     return EmitCompoundAssign(E, &ComplexExprEmitter::EmitBinSub);
169   }
170   ComplexPairTy VisitBinMulAssign(const CompoundAssignOperator *E) {
171     return EmitCompoundAssign(E, &ComplexExprEmitter::EmitBinMul);
172   }
173   ComplexPairTy VisitBinDivAssign(const CompoundAssignOperator *E) {
174     return EmitCompoundAssign(E, &ComplexExprEmitter::EmitBinDiv);
175   }
176 
177   // GCC rejects rem/and/or/xor for integer complex.
178   // Logical and/or always return int, never complex.
179 
180   // No comparisons produce a complex result.
181   ComplexPairTy VisitBinAssign     (const BinaryOperator *E);
182   ComplexPairTy VisitBinComma      (const BinaryOperator *E);
183 
184 
185   ComplexPairTy VisitConditionalOperator(const ConditionalOperator *CO);
186   ComplexPairTy VisitChooseExpr(ChooseExpr *CE);
187 
188   ComplexPairTy VisitInitListExpr(InitListExpr *E);
189 };
190 }  // end anonymous namespace.
191 
192 //===----------------------------------------------------------------------===//
193 //                                Utilities
194 //===----------------------------------------------------------------------===//
195 
196 /// EmitLoadOfComplex - Given an RValue reference for a complex, emit code to
197 /// load the real and imaginary pieces, returning them as Real/Imag.
198 ComplexPairTy ComplexExprEmitter::EmitLoadOfComplex(llvm::Value *SrcPtr,
199                                                     bool isVolatile) {
200   llvm::SmallString<64> Name(SrcPtr->getNameStart(),
201                              SrcPtr->getNameStart()+SrcPtr->getNameLen());
202 
203   Name += ".realp";
204   llvm::Value *RealPtr = Builder.CreateStructGEP(SrcPtr, 0, Name.c_str());
205 
206   Name.pop_back();  // .realp -> .real
207   llvm::Value *Real = Builder.CreateLoad(RealPtr, isVolatile, Name.c_str());
208 
209   Name.resize(Name.size()-4); // .real -> .imagp
210   Name += "imagp";
211 
212   llvm::Value *ImagPtr = Builder.CreateStructGEP(SrcPtr, 1, Name.c_str());
213 
214   Name.pop_back();  // .imagp -> .imag
215   llvm::Value *Imag = Builder.CreateLoad(ImagPtr, isVolatile, Name.c_str());
216   return ComplexPairTy(Real, Imag);
217 }
218 
219 /// EmitStoreOfComplex - Store the specified real/imag parts into the
220 /// specified value pointer.
221 void ComplexExprEmitter::EmitStoreOfComplex(ComplexPairTy Val, llvm::Value *Ptr,
222                                             bool isVolatile) {
223   llvm::Value *RealPtr = Builder.CreateStructGEP(Ptr, 0, "real");
224   llvm::Value *ImagPtr = Builder.CreateStructGEP(Ptr, 1, "imag");
225 
226   Builder.CreateStore(Val.first, RealPtr, isVolatile);
227   Builder.CreateStore(Val.second, ImagPtr, isVolatile);
228 }
229 
230 
231 
232 //===----------------------------------------------------------------------===//
233 //                            Visitor Methods
234 //===----------------------------------------------------------------------===//
235 
236 ComplexPairTy ComplexExprEmitter::VisitExpr(Expr *E) {
237   CGF.ErrorUnsupported(E, "complex expression");
238   const llvm::Type *EltTy =
239     CGF.ConvertType(E->getType()->getAsComplexType()->getElementType());
240   llvm::Value *U = llvm::UndefValue::get(EltTy);
241   return ComplexPairTy(U, U);
242 }
243 
244 ComplexPairTy ComplexExprEmitter::
245 VisitImaginaryLiteral(const ImaginaryLiteral *IL) {
246   llvm::Value *Imag = CGF.EmitScalarExpr(IL->getSubExpr());
247   return ComplexPairTy(llvm::Constant::getNullValue(Imag->getType()), Imag);
248 }
249 
250 
251 ComplexPairTy ComplexExprEmitter::VisitCallExpr(const CallExpr *E) {
252   return CGF.EmitCallExpr(E).getComplexVal();
253 }
254 
255 ComplexPairTy ComplexExprEmitter::VisitOverloadExpr(const OverloadExpr *E) {
256   return CGF.EmitCallExpr(E->getFn(), E->arg_begin(),
257                           E->arg_end(CGF.getContext())).getComplexVal();
258 }
259 
260 ComplexPairTy ComplexExprEmitter::VisitStmtExpr(const StmtExpr *E) {
261   return CGF.EmitCompoundStmt(*E->getSubStmt(), true).getComplexVal();
262 }
263 
264 /// EmitComplexToComplexCast - Emit a cast from complex value Val to DestType.
265 ComplexPairTy ComplexExprEmitter::EmitComplexToComplexCast(ComplexPairTy Val,
266                                                            QualType SrcType,
267                                                            QualType DestType) {
268   // Get the src/dest element type.
269   SrcType = SrcType->getAsComplexType()->getElementType();
270   DestType = DestType->getAsComplexType()->getElementType();
271 
272   // C99 6.3.1.6: When a value of complextype is converted to another
273   // complex type, both the real and imaginary parts follow the conversion
274   // rules for the corresponding real types.
275   Val.first = CGF.EmitScalarConversion(Val.first, SrcType, DestType);
276   Val.second = CGF.EmitScalarConversion(Val.second, SrcType, DestType);
277   return Val;
278 }
279 
280 ComplexPairTy ComplexExprEmitter::EmitCast(Expr *Op, QualType DestTy) {
281   // Two cases here: cast from (complex to complex) and (scalar to complex).
282   if (Op->getType()->isAnyComplexType())
283     return EmitComplexToComplexCast(Visit(Op), Op->getType(), DestTy);
284 
285   // C99 6.3.1.7: When a value of real type is converted to a complex type, the
286   // real part of the complex  result value is determined by the rules of
287   // conversion to the corresponding real type and the imaginary part of the
288   // complex result value is a positive zero or an unsigned zero.
289   llvm::Value *Elt = CGF.EmitScalarExpr(Op);
290 
291   // Convert the input element to the element type of the complex.
292   DestTy = DestTy->getAsComplexType()->getElementType();
293   Elt = CGF.EmitScalarConversion(Elt, Op->getType(), DestTy);
294 
295   // Return (realval, 0).
296   return ComplexPairTy(Elt, llvm::Constant::getNullValue(Elt->getType()));
297 }
298 
299 ComplexPairTy ComplexExprEmitter::VisitPrePostIncDec(const UnaryOperator *E,
300                                                      bool isInc, bool isPre) {
301   LValue LV = CGF.EmitLValue(E->getSubExpr());
302   // FIXME: Handle volatile!
303   ComplexPairTy InVal = EmitLoadOfComplex(LV.getAddress(), false);
304 
305   uint64_t AmountVal = isInc ? 1 : -1;
306 
307   llvm::Value *NextVal;
308   if (isa<llvm::IntegerType>(InVal.first->getType()))
309     NextVal = llvm::ConstantInt::get(InVal.first->getType(), AmountVal);
310   else if (InVal.first->getType() == llvm::Type::FloatTy)
311     // FIXME: Handle long double.
312     NextVal =
313       llvm::ConstantFP::get(llvm::APFloat(static_cast<float>(AmountVal)));
314   else {
315     // FIXME: Handle long double.
316     assert(InVal.first->getType() == llvm::Type::DoubleTy);
317     NextVal =
318       llvm::ConstantFP::get(llvm::APFloat(static_cast<double>(AmountVal)));
319   }
320 
321   // Add the inc/dec to the real part.
322   NextVal = Builder.CreateAdd(InVal.first, NextVal, isInc ? "inc" : "dec");
323 
324   ComplexPairTy IncVal(NextVal, InVal.second);
325 
326   // Store the updated result through the lvalue.
327   EmitStoreOfComplex(IncVal, LV.getAddress(), false);  /* FIXME: Volatile */
328 
329   // If this is a postinc, return the value read from memory, otherwise use the
330   // updated value.
331   return isPre ? IncVal : InVal;
332 }
333 
334 ComplexPairTy ComplexExprEmitter::VisitUnaryMinus(const UnaryOperator *E) {
335   ComplexPairTy Op = Visit(E->getSubExpr());
336   llvm::Value *ResR = Builder.CreateNeg(Op.first,  "neg.r");
337   llvm::Value *ResI = Builder.CreateNeg(Op.second, "neg.i");
338   return ComplexPairTy(ResR, ResI);
339 }
340 
341 ComplexPairTy ComplexExprEmitter::VisitUnaryNot(const UnaryOperator *E) {
342   // ~(a+ib) = a + i*-b
343   ComplexPairTy Op = Visit(E->getSubExpr());
344   llvm::Value *ResI = Builder.CreateNeg(Op.second, "conj.i");
345   return ComplexPairTy(Op.first, ResI);
346 }
347 
348 ComplexPairTy ComplexExprEmitter::EmitBinAdd(const BinOpInfo &Op) {
349   llvm::Value *ResR = Builder.CreateAdd(Op.LHS.first,  Op.RHS.first,  "add.r");
350   llvm::Value *ResI = Builder.CreateAdd(Op.LHS.second, Op.RHS.second, "add.i");
351   return ComplexPairTy(ResR, ResI);
352 }
353 
354 ComplexPairTy ComplexExprEmitter::EmitBinSub(const BinOpInfo &Op) {
355   llvm::Value *ResR = Builder.CreateSub(Op.LHS.first,  Op.RHS.first,  "sub.r");
356   llvm::Value *ResI = Builder.CreateSub(Op.LHS.second, Op.RHS.second, "sub.i");
357   return ComplexPairTy(ResR, ResI);
358 }
359 
360 
361 ComplexPairTy ComplexExprEmitter::EmitBinMul(const BinOpInfo &Op) {
362   llvm::Value *ResRl = Builder.CreateMul(Op.LHS.first, Op.RHS.first, "mul.rl");
363   llvm::Value *ResRr = Builder.CreateMul(Op.LHS.second, Op.RHS.second,"mul.rr");
364   llvm::Value *ResR  = Builder.CreateSub(ResRl, ResRr, "mul.r");
365 
366   llvm::Value *ResIl = Builder.CreateMul(Op.LHS.second, Op.RHS.first, "mul.il");
367   llvm::Value *ResIr = Builder.CreateMul(Op.LHS.first, Op.RHS.second, "mul.ir");
368   llvm::Value *ResI  = Builder.CreateAdd(ResIl, ResIr, "mul.i");
369   return ComplexPairTy(ResR, ResI);
370 }
371 
372 ComplexPairTy ComplexExprEmitter::EmitBinDiv(const BinOpInfo &Op) {
373   llvm::Value *LHSr = Op.LHS.first, *LHSi = Op.LHS.second;
374   llvm::Value *RHSr = Op.RHS.first, *RHSi = Op.RHS.second;
375 
376   // (a+ib) / (c+id) = ((ac+bd)/(cc+dd)) + i((bc-ad)/(cc+dd))
377   llvm::Value *Tmp1 = Builder.CreateMul(LHSr, RHSr, "tmp"); // a*c
378   llvm::Value *Tmp2 = Builder.CreateMul(LHSi, RHSi, "tmp"); // b*d
379   llvm::Value *Tmp3 = Builder.CreateAdd(Tmp1, Tmp2, "tmp"); // ac+bd
380 
381   llvm::Value *Tmp4 = Builder.CreateMul(RHSr, RHSr, "tmp"); // c*c
382   llvm::Value *Tmp5 = Builder.CreateMul(RHSi, RHSi, "tmp"); // d*d
383   llvm::Value *Tmp6 = Builder.CreateAdd(Tmp4, Tmp5, "tmp"); // cc+dd
384 
385   llvm::Value *Tmp7 = Builder.CreateMul(LHSi, RHSr, "tmp"); // b*c
386   llvm::Value *Tmp8 = Builder.CreateMul(LHSr, RHSi, "tmp"); // a*d
387   llvm::Value *Tmp9 = Builder.CreateSub(Tmp7, Tmp8, "tmp"); // bc-ad
388 
389   llvm::Value *DSTr, *DSTi;
390   if (Tmp3->getType()->isFloatingPoint()) {
391     DSTr = Builder.CreateFDiv(Tmp3, Tmp6, "tmp");
392     DSTi = Builder.CreateFDiv(Tmp9, Tmp6, "tmp");
393   } else {
394     if (Op.Ty->getAsComplexType()->getElementType()->isUnsignedIntegerType()) {
395       DSTr = Builder.CreateUDiv(Tmp3, Tmp6, "tmp");
396       DSTi = Builder.CreateUDiv(Tmp9, Tmp6, "tmp");
397     } else {
398       DSTr = Builder.CreateSDiv(Tmp3, Tmp6, "tmp");
399       DSTi = Builder.CreateSDiv(Tmp9, Tmp6, "tmp");
400     }
401   }
402 
403   return ComplexPairTy(DSTr, DSTi);
404 }
405 
406 ComplexExprEmitter::BinOpInfo
407 ComplexExprEmitter::EmitBinOps(const BinaryOperator *E) {
408   BinOpInfo Ops;
409   Ops.LHS = Visit(E->getLHS());
410   Ops.RHS = Visit(E->getRHS());
411   Ops.Ty = E->getType();
412   return Ops;
413 }
414 
415 
416 // Compound assignments.
417 ComplexPairTy ComplexExprEmitter::
418 EmitCompoundAssign(const CompoundAssignOperator *E,
419                    ComplexPairTy (ComplexExprEmitter::*Func)(const BinOpInfo&)){
420   QualType LHSTy = E->getLHS()->getType(), RHSTy = E->getRHS()->getType();
421 
422   // Load the LHS and RHS operands.
423   LValue LHSLV = CGF.EmitLValue(E->getLHS());
424 
425   BinOpInfo OpInfo;
426   OpInfo.Ty = E->getComputationType();
427 
428   // We know the LHS is a complex lvalue.
429   OpInfo.LHS = EmitLoadOfComplex(LHSLV.getAddress(), false);// FIXME: Volatile.
430   OpInfo.LHS = EmitComplexToComplexCast(OpInfo.LHS, LHSTy, OpInfo.Ty);
431 
432   // It is possible for the RHS to be complex or scalar.
433   OpInfo.RHS = EmitCast(E->getRHS(), OpInfo.Ty);
434 
435   // Expand the binary operator.
436   ComplexPairTy Result = (this->*Func)(OpInfo);
437 
438   // Truncate the result back to the LHS type.
439   Result = EmitComplexToComplexCast(Result, OpInfo.Ty, LHSTy);
440 
441   // Store the result value into the LHS lvalue.
442   EmitStoreOfComplex(Result, LHSLV.getAddress(), false); // FIXME: VOLATILE
443   return Result;
444 }
445 
446 ComplexPairTy ComplexExprEmitter::VisitBinAssign(const BinaryOperator *E) {
447   assert(CGF.getContext().getCanonicalType(E->getLHS()->getType()) ==
448          CGF.getContext().getCanonicalType(E->getRHS()->getType()) &&
449          "Invalid assignment");
450   // Emit the RHS.
451   ComplexPairTy Val = Visit(E->getRHS());
452 
453   // Compute the address to store into.
454   LValue LHS = CGF.EmitLValue(E->getLHS());
455 
456   // Store into it.
457   // FIXME: Volatility!
458   EmitStoreOfComplex(Val, LHS.getAddress(), false);
459   return Val;
460 }
461 
462 ComplexPairTy ComplexExprEmitter::VisitBinComma(const BinaryOperator *E) {
463   CGF.EmitStmt(E->getLHS());
464   CGF.EnsureInsertPoint();
465   return Visit(E->getRHS());
466 }
467 
468 ComplexPairTy ComplexExprEmitter::
469 VisitConditionalOperator(const ConditionalOperator *E) {
470   llvm::BasicBlock *LHSBlock = CGF.createBasicBlock("cond.true");
471   llvm::BasicBlock *RHSBlock = CGF.createBasicBlock("cond.false");
472   llvm::BasicBlock *ContBlock = CGF.createBasicBlock("cond.end");
473 
474   llvm::Value *Cond = CGF.EvaluateExprAsBool(E->getCond());
475   Builder.CreateCondBr(Cond, LHSBlock, RHSBlock);
476 
477   CGF.EmitBlock(LHSBlock);
478 
479   // Handle the GNU extension for missing LHS.
480   assert(E->getLHS() && "Must have LHS for complex value");
481 
482   ComplexPairTy LHS = Visit(E->getLHS());
483   LHSBlock = Builder.GetInsertBlock();
484   CGF.EmitBranch(ContBlock);
485 
486   CGF.EmitBlock(RHSBlock);
487 
488   ComplexPairTy RHS = Visit(E->getRHS());
489   RHSBlock = Builder.GetInsertBlock();
490   CGF.EmitBranch(ContBlock);
491 
492   CGF.EmitBlock(ContBlock);
493 
494   // Create a PHI node for the real part.
495   llvm::PHINode *RealPN = Builder.CreatePHI(LHS.first->getType(), "cond.r");
496   RealPN->reserveOperandSpace(2);
497   RealPN->addIncoming(LHS.first, LHSBlock);
498   RealPN->addIncoming(RHS.first, RHSBlock);
499 
500   // Create a PHI node for the imaginary part.
501   llvm::PHINode *ImagPN = Builder.CreatePHI(LHS.first->getType(), "cond.i");
502   ImagPN->reserveOperandSpace(2);
503   ImagPN->addIncoming(LHS.second, LHSBlock);
504   ImagPN->addIncoming(RHS.second, RHSBlock);
505 
506   return ComplexPairTy(RealPN, ImagPN);
507 }
508 
509 ComplexPairTy ComplexExprEmitter::VisitChooseExpr(ChooseExpr *E) {
510   // Emit the LHS or RHS as appropriate.
511   return Visit(E->isConditionTrue(CGF.getContext()) ? E->getLHS() :E->getRHS());
512 }
513 
514 ComplexPairTy ComplexExprEmitter::VisitInitListExpr(InitListExpr *E) {
515   if (E->getNumInits())
516     return Visit(E->getInit(0));
517 
518   // Empty init list intializes to null
519   QualType Ty = E->getType()->getAsComplexType()->getElementType();
520   const llvm::Type* LTy = CGF.ConvertType(Ty);
521   llvm::Value* zeroConstant = llvm::Constant::getNullValue(LTy);
522   return ComplexPairTy(zeroConstant, zeroConstant);
523 }
524 
525 //===----------------------------------------------------------------------===//
526 //                         Entry Point into this File
527 //===----------------------------------------------------------------------===//
528 
529 /// EmitComplexExpr - Emit the computation of the specified expression of
530 /// complex type, ignoring the result.
531 ComplexPairTy CodeGenFunction::EmitComplexExpr(const Expr *E) {
532   assert(E && E->getType()->isAnyComplexType() &&
533          "Invalid complex expression to emit");
534 
535   return ComplexExprEmitter(*this).Visit(const_cast<Expr*>(E));
536 }
537 
538 /// EmitComplexExprIntoAddr - Emit the computation of the specified expression
539 /// of complex type, storing into the specified Value*.
540 void CodeGenFunction::EmitComplexExprIntoAddr(const Expr *E,
541                                               llvm::Value *DestAddr,
542                                               bool DestIsVolatile) {
543   assert(E && E->getType()->isAnyComplexType() &&
544          "Invalid complex expression to emit");
545   ComplexExprEmitter Emitter(*this);
546   ComplexPairTy Val = Emitter.Visit(const_cast<Expr*>(E));
547   Emitter.EmitStoreOfComplex(Val, DestAddr, DestIsVolatile);
548 }
549 
550 /// StoreComplexToAddr - Store a complex number into the specified address.
551 void CodeGenFunction::StoreComplexToAddr(ComplexPairTy V,
552                                          llvm::Value *DestAddr,
553                                          bool DestIsVolatile) {
554   ComplexExprEmitter(*this).EmitStoreOfComplex(V, DestAddr, DestIsVolatile);
555 }
556 
557 /// LoadComplexFromAddr - Load a complex number from the specified address.
558 ComplexPairTy CodeGenFunction::LoadComplexFromAddr(llvm::Value *SrcAddr,
559                                                    bool SrcIsVolatile) {
560   return ComplexExprEmitter(*this).EmitLoadOfComplex(SrcAddr, SrcIsVolatile);
561 }
562