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     return EmitLoadOfComplex(LV.getAddress(), LV.isVolatileQualified());
51   }
52 
53   /// EmitLoadOfComplex - Given a pointer to a complex value, emit code to load
54   /// the real and imaginary pieces.
55   ComplexPairTy EmitLoadOfComplex(llvm::Value *SrcPtr, bool isVolatile);
56 
57   /// EmitStoreOfComplex - Store the specified real/imag parts into the
58   /// specified value pointer.
59   void EmitStoreOfComplex(ComplexPairTy Val, llvm::Value *ResPtr, bool isVol);
60 
61   /// EmitComplexToComplexCast - Emit a cast from complex value Val to DestType.
62   ComplexPairTy EmitComplexToComplexCast(ComplexPairTy Val, QualType SrcType,
63                                          QualType DestType);
64 
65   //===--------------------------------------------------------------------===//
66   //                            Visitor Methods
67   //===--------------------------------------------------------------------===//
68 
69   ComplexPairTy VisitStmt(Stmt *S) {
70     S->dump(CGF.getContext().getSourceManager());
71     assert(0 && "Stmt can't have complex result type!");
72     return ComplexPairTy();
73   }
74   ComplexPairTy VisitExpr(Expr *S);
75   ComplexPairTy VisitParenExpr(ParenExpr *PE) { return Visit(PE->getSubExpr());}
76   ComplexPairTy VisitImaginaryLiteral(const ImaginaryLiteral *IL);
77 
78   // l-values.
79   ComplexPairTy VisitDeclRefExpr(const Expr *E) { return EmitLoadOfLValue(E); }
80   ComplexPairTy VisitArraySubscriptExpr(Expr *E) { return EmitLoadOfLValue(E); }
81   ComplexPairTy VisitMemberExpr(const Expr *E) { return EmitLoadOfLValue(E); }
82 
83   // FIXME: CompoundLiteralExpr
84 
85   ComplexPairTy EmitCast(Expr *Op, QualType DestTy);
86   ComplexPairTy VisitImplicitCastExpr(ImplicitCastExpr *E) {
87     // Unlike for scalars, we don't have to worry about function->ptr demotion
88     // here.
89     return EmitCast(E->getSubExpr(), E->getType());
90   }
91   ComplexPairTy VisitCastExpr(CastExpr *E) {
92     return EmitCast(E->getSubExpr(), E->getType());
93   }
94   ComplexPairTy VisitCallExpr(const CallExpr *E);
95   ComplexPairTy VisitStmtExpr(const StmtExpr *E);
96 
97   // Operators.
98   ComplexPairTy VisitPrePostIncDec(const UnaryOperator *E,
99                                    bool isInc, bool isPre);
100   ComplexPairTy VisitUnaryPostDec(const UnaryOperator *E) {
101     return VisitPrePostIncDec(E, false, false);
102   }
103   ComplexPairTy VisitUnaryPostInc(const UnaryOperator *E) {
104     return VisitPrePostIncDec(E, true, false);
105   }
106   ComplexPairTy VisitUnaryPreDec(const UnaryOperator *E) {
107     return VisitPrePostIncDec(E, false, true);
108   }
109   ComplexPairTy VisitUnaryPreInc(const UnaryOperator *E) {
110     return VisitPrePostIncDec(E, true, true);
111   }
112   ComplexPairTy VisitUnaryDeref(const Expr *E) { return EmitLoadOfLValue(E); }
113   ComplexPairTy VisitUnaryPlus     (const UnaryOperator *E) {
114     return Visit(E->getSubExpr());
115   }
116   ComplexPairTy VisitUnaryMinus    (const UnaryOperator *E);
117   ComplexPairTy VisitUnaryNot      (const UnaryOperator *E);
118   // LNot,Real,Imag never return complex.
119   ComplexPairTy VisitUnaryExtension(const UnaryOperator *E) {
120     return Visit(E->getSubExpr());
121   }
122   ComplexPairTy VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) {
123     return Visit(DAE->getExpr());
124   }
125   ComplexPairTy VisitCXXZeroInitValueExpr(CXXZeroInitValueExpr *E) {
126     assert(E->getType()->isAnyComplexType() && "Expected complex type!");
127     QualType Elem = E->getType()->getAsComplexType()->getElementType();
128     llvm::Constant *Null = llvm::Constant::getNullValue(CGF.ConvertType(Elem));
129     return ComplexPairTy(Null, Null);
130   }
131   ComplexPairTy VisitImplicitValueInitExpr(ImplicitValueInitExpr *E) {
132     assert(E->getType()->isAnyComplexType() && "Expected complex type!");
133     QualType Elem = E->getType()->getAsComplexType()->getElementType();
134     llvm::Constant *Null = llvm::Constant::getNullValue(CGF.ConvertType(Elem));
135     return ComplexPairTy(Null, Null);
136   }
137 
138   struct BinOpInfo {
139     ComplexPairTy LHS;
140     ComplexPairTy RHS;
141     QualType Ty;  // Computation Type.
142   };
143 
144   BinOpInfo EmitBinOps(const BinaryOperator *E);
145   ComplexPairTy EmitCompoundAssign(const CompoundAssignOperator *E,
146                                    ComplexPairTy (ComplexExprEmitter::*Func)
147                                    (const BinOpInfo &));
148 
149   ComplexPairTy EmitBinAdd(const BinOpInfo &Op);
150   ComplexPairTy EmitBinSub(const BinOpInfo &Op);
151   ComplexPairTy EmitBinMul(const BinOpInfo &Op);
152   ComplexPairTy EmitBinDiv(const BinOpInfo &Op);
153 
154   ComplexPairTy VisitBinMul(const BinaryOperator *E) {
155     return EmitBinMul(EmitBinOps(E));
156   }
157   ComplexPairTy VisitBinAdd(const BinaryOperator *E) {
158     return EmitBinAdd(EmitBinOps(E));
159   }
160   ComplexPairTy VisitBinSub(const BinaryOperator *E) {
161     return EmitBinSub(EmitBinOps(E));
162   }
163   ComplexPairTy VisitBinDiv(const BinaryOperator *E) {
164     return EmitBinDiv(EmitBinOps(E));
165   }
166 
167   // Compound assignments.
168   ComplexPairTy VisitBinAddAssign(const CompoundAssignOperator *E) {
169     return EmitCompoundAssign(E, &ComplexExprEmitter::EmitBinAdd);
170   }
171   ComplexPairTy VisitBinSubAssign(const CompoundAssignOperator *E) {
172     return EmitCompoundAssign(E, &ComplexExprEmitter::EmitBinSub);
173   }
174   ComplexPairTy VisitBinMulAssign(const CompoundAssignOperator *E) {
175     return EmitCompoundAssign(E, &ComplexExprEmitter::EmitBinMul);
176   }
177   ComplexPairTy VisitBinDivAssign(const CompoundAssignOperator *E) {
178     return EmitCompoundAssign(E, &ComplexExprEmitter::EmitBinDiv);
179   }
180 
181   // GCC rejects rem/and/or/xor for integer complex.
182   // Logical and/or always return int, never complex.
183 
184   // No comparisons produce a complex result.
185   ComplexPairTy VisitBinAssign     (const BinaryOperator *E);
186   ComplexPairTy VisitBinComma      (const BinaryOperator *E);
187 
188 
189   ComplexPairTy VisitConditionalOperator(const ConditionalOperator *CO);
190   ComplexPairTy VisitChooseExpr(ChooseExpr *CE);
191 
192   ComplexPairTy VisitInitListExpr(InitListExpr *E);
193 
194   ComplexPairTy VisitVAArgExpr(VAArgExpr *E);
195 };
196 }  // end anonymous namespace.
197 
198 //===----------------------------------------------------------------------===//
199 //                                Utilities
200 //===----------------------------------------------------------------------===//
201 
202 /// EmitLoadOfComplex - Given an RValue reference for a complex, emit code to
203 /// load the real and imaginary pieces, returning them as Real/Imag.
204 ComplexPairTy ComplexExprEmitter::EmitLoadOfComplex(llvm::Value *SrcPtr,
205                                                     bool isVolatile) {
206   llvm::SmallString<64> Name(SrcPtr->getNameStart(),
207                              SrcPtr->getNameStart()+SrcPtr->getNameLen());
208 
209   Name += ".realp";
210   llvm::Value *RealPtr = Builder.CreateStructGEP(SrcPtr, 0, Name.c_str());
211 
212   Name.pop_back();  // .realp -> .real
213   llvm::Value *Real = Builder.CreateLoad(RealPtr, isVolatile, Name.c_str());
214 
215   Name.resize(Name.size()-4); // .real -> .imagp
216   Name += "imagp";
217 
218   llvm::Value *ImagPtr = Builder.CreateStructGEP(SrcPtr, 1, Name.c_str());
219 
220   Name.pop_back();  // .imagp -> .imag
221   llvm::Value *Imag = Builder.CreateLoad(ImagPtr, isVolatile, Name.c_str());
222   return ComplexPairTy(Real, Imag);
223 }
224 
225 /// EmitStoreOfComplex - Store the specified real/imag parts into the
226 /// specified value pointer.
227 void ComplexExprEmitter::EmitStoreOfComplex(ComplexPairTy Val, llvm::Value *Ptr,
228                                             bool isVolatile) {
229   llvm::Value *RealPtr = Builder.CreateStructGEP(Ptr, 0, "real");
230   llvm::Value *ImagPtr = Builder.CreateStructGEP(Ptr, 1, "imag");
231 
232   Builder.CreateStore(Val.first, RealPtr, isVolatile);
233   Builder.CreateStore(Val.second, ImagPtr, isVolatile);
234 }
235 
236 
237 
238 //===----------------------------------------------------------------------===//
239 //                            Visitor Methods
240 //===----------------------------------------------------------------------===//
241 
242 ComplexPairTy ComplexExprEmitter::VisitExpr(Expr *E) {
243   CGF.ErrorUnsupported(E, "complex expression");
244   const llvm::Type *EltTy =
245     CGF.ConvertType(E->getType()->getAsComplexType()->getElementType());
246   llvm::Value *U = llvm::UndefValue::get(EltTy);
247   return ComplexPairTy(U, U);
248 }
249 
250 ComplexPairTy ComplexExprEmitter::
251 VisitImaginaryLiteral(const ImaginaryLiteral *IL) {
252   llvm::Value *Imag = CGF.EmitScalarExpr(IL->getSubExpr());
253   return ComplexPairTy(llvm::Constant::getNullValue(Imag->getType()), Imag);
254 }
255 
256 
257 ComplexPairTy ComplexExprEmitter::VisitCallExpr(const CallExpr *E) {
258   if (E->getCallReturnType()->isReferenceType())
259     return EmitLoadOfLValue(E);
260 
261   return CGF.EmitCallExpr(E).getComplexVal();
262 }
263 
264 ComplexPairTy ComplexExprEmitter::VisitStmtExpr(const StmtExpr *E) {
265   return CGF.EmitCompoundStmt(*E->getSubStmt(), true).getComplexVal();
266 }
267 
268 /// EmitComplexToComplexCast - Emit a cast from complex value Val to DestType.
269 ComplexPairTy ComplexExprEmitter::EmitComplexToComplexCast(ComplexPairTy Val,
270                                                            QualType SrcType,
271                                                            QualType DestType) {
272   // Get the src/dest element type.
273   SrcType = SrcType->getAsComplexType()->getElementType();
274   DestType = DestType->getAsComplexType()->getElementType();
275 
276   // C99 6.3.1.6: When a value of complex type is converted to another
277   // complex type, both the real and imaginary parts follow the conversion
278   // rules for the corresponding real types.
279   Val.first = CGF.EmitScalarConversion(Val.first, SrcType, DestType);
280   Val.second = CGF.EmitScalarConversion(Val.second, SrcType, DestType);
281   return Val;
282 }
283 
284 ComplexPairTy ComplexExprEmitter::EmitCast(Expr *Op, QualType DestTy) {
285   // Two cases here: cast from (complex to complex) and (scalar to complex).
286   if (Op->getType()->isAnyComplexType())
287     return EmitComplexToComplexCast(Visit(Op), Op->getType(), DestTy);
288 
289   // C99 6.3.1.7: When a value of real type is converted to a complex type, the
290   // real part of the complex result value is determined by the rules of
291   // conversion to the corresponding real type and the imaginary part of the
292   // complex result value is a positive zero or an unsigned zero.
293   llvm::Value *Elt = CGF.EmitScalarExpr(Op);
294 
295   // Convert the input element to the element type of the complex.
296   DestTy = DestTy->getAsComplexType()->getElementType();
297   Elt = CGF.EmitScalarConversion(Elt, Op->getType(), DestTy);
298 
299   // Return (realval, 0).
300   return ComplexPairTy(Elt, llvm::Constant::getNullValue(Elt->getType()));
301 }
302 
303 ComplexPairTy ComplexExprEmitter::VisitPrePostIncDec(const UnaryOperator *E,
304                                                      bool isInc, bool isPre) {
305   LValue LV = CGF.EmitLValue(E->getSubExpr());
306   ComplexPairTy InVal = EmitLoadOfComplex(LV.getAddress(), LV.isVolatileQualified());
307 
308   llvm::Value *NextVal;
309   if (isa<llvm::IntegerType>(InVal.first->getType())) {
310     uint64_t AmountVal = isInc ? 1 : -1;
311     NextVal = llvm::ConstantInt::get(InVal.first->getType(), AmountVal, true);
312   } else {
313     QualType ElemTy = E->getType()->getAsComplexType()->getElementType();
314     llvm::APFloat FVal(CGF.getContext().getFloatTypeSemantics(ElemTy), 1);
315     if (!isInc)
316       FVal.changeSign();
317     NextVal = llvm::ConstantFP::get(FVal);
318   }
319 
320   // Add the inc/dec to the real part.
321   NextVal = Builder.CreateAdd(InVal.first, NextVal, isInc ? "inc" : "dec");
322 
323   ComplexPairTy IncVal(NextVal, InVal.second);
324 
325   // Store the updated result through the lvalue.
326   EmitStoreOfComplex(IncVal, LV.getAddress(), LV.isVolatileQualified());
327 
328   // If this is a postinc, return the value read from memory, otherwise use the
329   // updated value.
330   return isPre ? IncVal : InVal;
331 }
332 
333 ComplexPairTy ComplexExprEmitter::VisitUnaryMinus(const UnaryOperator *E) {
334   ComplexPairTy Op = Visit(E->getSubExpr());
335   llvm::Value *ResR = Builder.CreateNeg(Op.first,  "neg.r");
336   llvm::Value *ResI = Builder.CreateNeg(Op.second, "neg.i");
337   return ComplexPairTy(ResR, ResI);
338 }
339 
340 ComplexPairTy ComplexExprEmitter::VisitUnaryNot(const UnaryOperator *E) {
341   // ~(a+ib) = a + i*-b
342   ComplexPairTy Op = Visit(E->getSubExpr());
343   llvm::Value *ResI = Builder.CreateNeg(Op.second, "conj.i");
344   return ComplexPairTy(Op.first, ResI);
345 }
346 
347 ComplexPairTy ComplexExprEmitter::EmitBinAdd(const BinOpInfo &Op) {
348   llvm::Value *ResR = Builder.CreateAdd(Op.LHS.first,  Op.RHS.first,  "add.r");
349   llvm::Value *ResI = Builder.CreateAdd(Op.LHS.second, Op.RHS.second, "add.i");
350   return ComplexPairTy(ResR, ResI);
351 }
352 
353 ComplexPairTy ComplexExprEmitter::EmitBinSub(const BinOpInfo &Op) {
354   llvm::Value *ResR = Builder.CreateSub(Op.LHS.first,  Op.RHS.first,  "sub.r");
355   llvm::Value *ResI = Builder.CreateSub(Op.LHS.second, Op.RHS.second, "sub.i");
356   return ComplexPairTy(ResR, ResI);
357 }
358 
359 
360 ComplexPairTy ComplexExprEmitter::EmitBinMul(const BinOpInfo &Op) {
361   llvm::Value *ResRl = Builder.CreateMul(Op.LHS.first, Op.RHS.first, "mul.rl");
362   llvm::Value *ResRr = Builder.CreateMul(Op.LHS.second, Op.RHS.second,"mul.rr");
363   llvm::Value *ResR  = Builder.CreateSub(ResRl, ResRr, "mul.r");
364 
365   llvm::Value *ResIl = Builder.CreateMul(Op.LHS.second, Op.RHS.first, "mul.il");
366   llvm::Value *ResIr = Builder.CreateMul(Op.LHS.first, Op.RHS.second, "mul.ir");
367   llvm::Value *ResI  = Builder.CreateAdd(ResIl, ResIr, "mul.i");
368   return ComplexPairTy(ResR, ResI);
369 }
370 
371 ComplexPairTy ComplexExprEmitter::EmitBinDiv(const BinOpInfo &Op) {
372   llvm::Value *LHSr = Op.LHS.first, *LHSi = Op.LHS.second;
373   llvm::Value *RHSr = Op.RHS.first, *RHSi = Op.RHS.second;
374 
375   // (a+ib) / (c+id) = ((ac+bd)/(cc+dd)) + i((bc-ad)/(cc+dd))
376   llvm::Value *Tmp1 = Builder.CreateMul(LHSr, RHSr, "tmp"); // a*c
377   llvm::Value *Tmp2 = Builder.CreateMul(LHSi, RHSi, "tmp"); // b*d
378   llvm::Value *Tmp3 = Builder.CreateAdd(Tmp1, Tmp2, "tmp"); // ac+bd
379 
380   llvm::Value *Tmp4 = Builder.CreateMul(RHSr, RHSr, "tmp"); // c*c
381   llvm::Value *Tmp5 = Builder.CreateMul(RHSi, RHSi, "tmp"); // d*d
382   llvm::Value *Tmp6 = Builder.CreateAdd(Tmp4, Tmp5, "tmp"); // cc+dd
383 
384   llvm::Value *Tmp7 = Builder.CreateMul(LHSi, RHSr, "tmp"); // b*c
385   llvm::Value *Tmp8 = Builder.CreateMul(LHSr, RHSi, "tmp"); // a*d
386   llvm::Value *Tmp9 = Builder.CreateSub(Tmp7, Tmp8, "tmp"); // bc-ad
387 
388   llvm::Value *DSTr, *DSTi;
389   if (Tmp3->getType()->isFloatingPoint()) {
390     DSTr = Builder.CreateFDiv(Tmp3, Tmp6, "tmp");
391     DSTi = Builder.CreateFDiv(Tmp9, Tmp6, "tmp");
392   } else {
393     if (Op.Ty->getAsComplexType()->getElementType()->isUnsignedIntegerType()) {
394       DSTr = Builder.CreateUDiv(Tmp3, Tmp6, "tmp");
395       DSTi = Builder.CreateUDiv(Tmp9, Tmp6, "tmp");
396     } else {
397       DSTr = Builder.CreateSDiv(Tmp3, Tmp6, "tmp");
398       DSTi = Builder.CreateSDiv(Tmp9, Tmp6, "tmp");
399     }
400   }
401 
402   return ComplexPairTy(DSTr, DSTi);
403 }
404 
405 ComplexExprEmitter::BinOpInfo
406 ComplexExprEmitter::EmitBinOps(const BinaryOperator *E) {
407   BinOpInfo Ops;
408   Ops.LHS = Visit(E->getLHS());
409   Ops.RHS = Visit(E->getRHS());
410   Ops.Ty = E->getType();
411   return Ops;
412 }
413 
414 
415 // Compound assignments.
416 ComplexPairTy ComplexExprEmitter::
417 EmitCompoundAssign(const CompoundAssignOperator *E,
418                    ComplexPairTy (ComplexExprEmitter::*Func)(const BinOpInfo&)){
419   QualType LHSTy = E->getLHS()->getType(), RHSTy = E->getRHS()->getType();
420 
421   // Load the LHS and RHS operands.
422   LValue LHSLV = CGF.EmitLValue(E->getLHS());
423 
424   BinOpInfo OpInfo;
425   OpInfo.Ty = E->getComputationResultType();
426 
427   // We know the LHS is a complex lvalue.
428   OpInfo.LHS = EmitLoadOfComplex(LHSLV.getAddress(), LHSLV.isVolatileQualified());
429   OpInfo.LHS = EmitComplexToComplexCast(OpInfo.LHS, LHSTy, OpInfo.Ty);
430 
431   // It is possible for the RHS to be complex or scalar.
432   OpInfo.RHS = EmitCast(E->getRHS(), OpInfo.Ty);
433 
434   // Expand the binary operator.
435   ComplexPairTy Result = (this->*Func)(OpInfo);
436 
437   // Truncate the result back to the LHS type.
438   Result = EmitComplexToComplexCast(Result, OpInfo.Ty, LHSTy);
439 
440   // Store the result value into the LHS lvalue.
441   EmitStoreOfComplex(Result, LHSLV.getAddress(), LHSLV.isVolatileQualified());
442   return Result;
443 }
444 
445 ComplexPairTy ComplexExprEmitter::VisitBinAssign(const BinaryOperator *E) {
446   assert(CGF.getContext().getCanonicalType(E->getLHS()->getType()) ==
447          CGF.getContext().getCanonicalType(E->getRHS()->getType()) &&
448          "Invalid assignment");
449   // Emit the RHS.
450   ComplexPairTy Val = Visit(E->getRHS());
451 
452   // Compute the address to store into.
453   LValue LHS = CGF.EmitLValue(E->getLHS());
454 
455   // Store into it.
456   EmitStoreOfComplex(Val, LHS.getAddress(), LHS.isVolatileQualified());
457   return Val;
458 }
459 
460 ComplexPairTy ComplexExprEmitter::VisitBinComma(const BinaryOperator *E) {
461   CGF.EmitStmt(E->getLHS());
462   CGF.EnsureInsertPoint();
463   return Visit(E->getRHS());
464 }
465 
466 ComplexPairTy ComplexExprEmitter::
467 VisitConditionalOperator(const ConditionalOperator *E) {
468   llvm::BasicBlock *LHSBlock = CGF.createBasicBlock("cond.true");
469   llvm::BasicBlock *RHSBlock = CGF.createBasicBlock("cond.false");
470   llvm::BasicBlock *ContBlock = CGF.createBasicBlock("cond.end");
471 
472   llvm::Value *Cond = CGF.EvaluateExprAsBool(E->getCond());
473   Builder.CreateCondBr(Cond, LHSBlock, RHSBlock);
474 
475   CGF.EmitBlock(LHSBlock);
476 
477   // Handle the GNU extension for missing LHS.
478   assert(E->getLHS() && "Must have LHS for complex value");
479 
480   ComplexPairTy LHS = Visit(E->getLHS());
481   LHSBlock = Builder.GetInsertBlock();
482   CGF.EmitBranch(ContBlock);
483 
484   CGF.EmitBlock(RHSBlock);
485 
486   ComplexPairTy RHS = Visit(E->getRHS());
487   RHSBlock = Builder.GetInsertBlock();
488   CGF.EmitBranch(ContBlock);
489 
490   CGF.EmitBlock(ContBlock);
491 
492   // Create a PHI node for the real part.
493   llvm::PHINode *RealPN = Builder.CreatePHI(LHS.first->getType(), "cond.r");
494   RealPN->reserveOperandSpace(2);
495   RealPN->addIncoming(LHS.first, LHSBlock);
496   RealPN->addIncoming(RHS.first, RHSBlock);
497 
498   // Create a PHI node for the imaginary part.
499   llvm::PHINode *ImagPN = Builder.CreatePHI(LHS.first->getType(), "cond.i");
500   ImagPN->reserveOperandSpace(2);
501   ImagPN->addIncoming(LHS.second, LHSBlock);
502   ImagPN->addIncoming(RHS.second, RHSBlock);
503 
504   return ComplexPairTy(RealPN, ImagPN);
505 }
506 
507 ComplexPairTy ComplexExprEmitter::VisitChooseExpr(ChooseExpr *E) {
508   return Visit(E->getChosenSubExpr(CGF.getContext()));
509 }
510 
511 ComplexPairTy ComplexExprEmitter::VisitInitListExpr(InitListExpr *E) {
512   if (E->getNumInits())
513     return Visit(E->getInit(0));
514 
515   // Empty init list intializes to null
516   QualType Ty = E->getType()->getAsComplexType()->getElementType();
517   const llvm::Type* LTy = CGF.ConvertType(Ty);
518   llvm::Value* zeroConstant = llvm::Constant::getNullValue(LTy);
519   return ComplexPairTy(zeroConstant, zeroConstant);
520 }
521 
522 ComplexPairTy ComplexExprEmitter::VisitVAArgExpr(VAArgExpr *E) {
523   llvm::Value *ArgValue = CGF.EmitVAListRef(E->getSubExpr());
524   llvm::Value *ArgPtr = CGF.EmitVAArg(ArgValue, E->getType());
525 
526   if (!ArgPtr) {
527     CGF.ErrorUnsupported(E, "complex va_arg expression");
528     const llvm::Type *EltTy =
529       CGF.ConvertType(E->getType()->getAsComplexType()->getElementType());
530     llvm::Value *U = llvm::UndefValue::get(EltTy);
531     return ComplexPairTy(U, U);
532   }
533 
534   // FIXME Volatility.
535   return EmitLoadOfComplex(ArgPtr, false);
536 }
537 
538 //===----------------------------------------------------------------------===//
539 //                         Entry Point into this File
540 //===----------------------------------------------------------------------===//
541 
542 /// EmitComplexExpr - Emit the computation of the specified expression of
543 /// complex type, ignoring the result.
544 ComplexPairTy CodeGenFunction::EmitComplexExpr(const Expr *E) {
545   assert(E && E->getType()->isAnyComplexType() &&
546          "Invalid complex expression to emit");
547 
548   return ComplexExprEmitter(*this).Visit(const_cast<Expr*>(E));
549 }
550 
551 /// EmitComplexExprIntoAddr - Emit the computation of the specified expression
552 /// of complex type, storing into the specified Value*.
553 void CodeGenFunction::EmitComplexExprIntoAddr(const Expr *E,
554                                               llvm::Value *DestAddr,
555                                               bool DestIsVolatile) {
556   assert(E && E->getType()->isAnyComplexType() &&
557          "Invalid complex expression to emit");
558   ComplexExprEmitter Emitter(*this);
559   ComplexPairTy Val = Emitter.Visit(const_cast<Expr*>(E));
560   Emitter.EmitStoreOfComplex(Val, DestAddr, DestIsVolatile);
561 }
562 
563 /// StoreComplexToAddr - Store a complex number into the specified address.
564 void CodeGenFunction::StoreComplexToAddr(ComplexPairTy V,
565                                          llvm::Value *DestAddr,
566                                          bool DestIsVolatile) {
567   ComplexExprEmitter(*this).EmitStoreOfComplex(V, DestAddr, DestIsVolatile);
568 }
569 
570 /// LoadComplexFromAddr - Load a complex number from the specified address.
571 ComplexPairTy CodeGenFunction::LoadComplexFromAddr(llvm::Value *SrcAddr,
572                                                    bool SrcIsVolatile) {
573   return ComplexExprEmitter(*this).EmitLoadOfComplex(SrcAddr, SrcIsVolatile);
574 }
575