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 
98   // Operators.
99   ComplexPairTy VisitPrePostIncDec(const UnaryOperator *E,
100                                    bool isInc, bool isPre);
101   ComplexPairTy VisitUnaryPostDec(const UnaryOperator *E) {
102     return VisitPrePostIncDec(E, false, false);
103   }
104   ComplexPairTy VisitUnaryPostInc(const UnaryOperator *E) {
105     return VisitPrePostIncDec(E, true, false);
106   }
107   ComplexPairTy VisitUnaryPreDec(const UnaryOperator *E) {
108     return VisitPrePostIncDec(E, false, true);
109   }
110   ComplexPairTy VisitUnaryPreInc(const UnaryOperator *E) {
111     return VisitPrePostIncDec(E, true, true);
112   }
113   ComplexPairTy VisitUnaryDeref(const Expr *E) { return EmitLoadOfLValue(E); }
114   ComplexPairTy VisitUnaryPlus     (const UnaryOperator *E) {
115     return Visit(E->getSubExpr());
116   }
117   ComplexPairTy VisitUnaryMinus    (const UnaryOperator *E);
118   ComplexPairTy VisitUnaryNot      (const UnaryOperator *E);
119   // LNot,Real,Imag never return complex.
120   ComplexPairTy VisitUnaryExtension(const UnaryOperator *E) {
121     return Visit(E->getSubExpr());
122   }
123   ComplexPairTy VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) {
124     return Visit(DAE->getExpr());
125   }
126   ComplexPairTy VisitCXXZeroInitValueExpr(CXXZeroInitValueExpr *E) {
127     assert(E->getType()->isAnyComplexType() && "Expected complex type!");
128     QualType Elem = E->getType()->getAsComplexType()->getElementType();
129     llvm::Constant *Null = llvm::Constant::getNullValue(CGF.ConvertType(Elem));
130     return ComplexPairTy(Null, Null);
131   }
132   ComplexPairTy VisitImplicitValueInitExpr(ImplicitValueInitExpr *E) {
133     assert(E->getType()->isAnyComplexType() && "Expected complex type!");
134     QualType Elem = E->getType()->getAsComplexType()->getElementType();
135     llvm::Constant *Null = llvm::Constant::getNullValue(CGF.ConvertType(Elem));
136     return ComplexPairTy(Null, Null);
137   }
138 
139   struct BinOpInfo {
140     ComplexPairTy LHS;
141     ComplexPairTy RHS;
142     QualType Ty;  // Computation Type.
143   };
144 
145   BinOpInfo EmitBinOps(const BinaryOperator *E);
146   ComplexPairTy EmitCompoundAssign(const CompoundAssignOperator *E,
147                                    ComplexPairTy (ComplexExprEmitter::*Func)
148                                    (const BinOpInfo &));
149 
150   ComplexPairTy EmitBinAdd(const BinOpInfo &Op);
151   ComplexPairTy EmitBinSub(const BinOpInfo &Op);
152   ComplexPairTy EmitBinMul(const BinOpInfo &Op);
153   ComplexPairTy EmitBinDiv(const BinOpInfo &Op);
154 
155   ComplexPairTy VisitBinMul(const BinaryOperator *E) {
156     return EmitBinMul(EmitBinOps(E));
157   }
158   ComplexPairTy VisitBinAdd(const BinaryOperator *E) {
159     return EmitBinAdd(EmitBinOps(E));
160   }
161   ComplexPairTy VisitBinSub(const BinaryOperator *E) {
162     return EmitBinSub(EmitBinOps(E));
163   }
164   ComplexPairTy VisitBinDiv(const BinaryOperator *E) {
165     return EmitBinDiv(EmitBinOps(E));
166   }
167 
168   // Compound assignments.
169   ComplexPairTy VisitBinAddAssign(const CompoundAssignOperator *E) {
170     return EmitCompoundAssign(E, &ComplexExprEmitter::EmitBinAdd);
171   }
172   ComplexPairTy VisitBinSubAssign(const CompoundAssignOperator *E) {
173     return EmitCompoundAssign(E, &ComplexExprEmitter::EmitBinSub);
174   }
175   ComplexPairTy VisitBinMulAssign(const CompoundAssignOperator *E) {
176     return EmitCompoundAssign(E, &ComplexExprEmitter::EmitBinMul);
177   }
178   ComplexPairTy VisitBinDivAssign(const CompoundAssignOperator *E) {
179     return EmitCompoundAssign(E, &ComplexExprEmitter::EmitBinDiv);
180   }
181 
182   // GCC rejects rem/and/or/xor for integer complex.
183   // Logical and/or always return int, never complex.
184 
185   // No comparisons produce a complex result.
186   ComplexPairTy VisitBinAssign     (const BinaryOperator *E);
187   ComplexPairTy VisitBinComma      (const BinaryOperator *E);
188 
189 
190   ComplexPairTy VisitConditionalOperator(const ConditionalOperator *CO);
191   ComplexPairTy VisitChooseExpr(ChooseExpr *CE);
192 
193   ComplexPairTy VisitInitListExpr(InitListExpr *E);
194 
195   ComplexPairTy VisitVAArgExpr(VAArgExpr *E);
196 };
197 }  // end anonymous namespace.
198 
199 //===----------------------------------------------------------------------===//
200 //                                Utilities
201 //===----------------------------------------------------------------------===//
202 
203 /// EmitLoadOfComplex - Given an RValue reference for a complex, emit code to
204 /// load the real and imaginary pieces, returning them as Real/Imag.
205 ComplexPairTy ComplexExprEmitter::EmitLoadOfComplex(llvm::Value *SrcPtr,
206                                                     bool isVolatile) {
207   llvm::SmallString<64> Name(SrcPtr->getNameStart(),
208                              SrcPtr->getNameStart()+SrcPtr->getNameLen());
209 
210   Name += ".realp";
211   llvm::Value *RealPtr = Builder.CreateStructGEP(SrcPtr, 0, Name.c_str());
212 
213   Name.pop_back();  // .realp -> .real
214   llvm::Value *Real = Builder.CreateLoad(RealPtr, isVolatile, Name.c_str());
215 
216   Name.resize(Name.size()-4); // .real -> .imagp
217   Name += "imagp";
218 
219   llvm::Value *ImagPtr = Builder.CreateStructGEP(SrcPtr, 1, Name.c_str());
220 
221   Name.pop_back();  // .imagp -> .imag
222   llvm::Value *Imag = Builder.CreateLoad(ImagPtr, isVolatile, Name.c_str());
223   return ComplexPairTy(Real, Imag);
224 }
225 
226 /// EmitStoreOfComplex - Store the specified real/imag parts into the
227 /// specified value pointer.
228 void ComplexExprEmitter::EmitStoreOfComplex(ComplexPairTy Val, llvm::Value *Ptr,
229                                             bool isVolatile) {
230   llvm::Value *RealPtr = Builder.CreateStructGEP(Ptr, 0, "real");
231   llvm::Value *ImagPtr = Builder.CreateStructGEP(Ptr, 1, "imag");
232 
233   Builder.CreateStore(Val.first, RealPtr, isVolatile);
234   Builder.CreateStore(Val.second, ImagPtr, isVolatile);
235 }
236 
237 
238 
239 //===----------------------------------------------------------------------===//
240 //                            Visitor Methods
241 //===----------------------------------------------------------------------===//
242 
243 ComplexPairTy ComplexExprEmitter::VisitExpr(Expr *E) {
244   CGF.ErrorUnsupported(E, "complex expression");
245   const llvm::Type *EltTy =
246     CGF.ConvertType(E->getType()->getAsComplexType()->getElementType());
247   llvm::Value *U = llvm::UndefValue::get(EltTy);
248   return ComplexPairTy(U, U);
249 }
250 
251 ComplexPairTy ComplexExprEmitter::
252 VisitImaginaryLiteral(const ImaginaryLiteral *IL) {
253   llvm::Value *Imag = CGF.EmitScalarExpr(IL->getSubExpr());
254   return ComplexPairTy(llvm::Constant::getNullValue(Imag->getType()), Imag);
255 }
256 
257 
258 ComplexPairTy ComplexExprEmitter::VisitCallExpr(const CallExpr *E) {
259   return CGF.EmitCallExpr(E).getComplexVal();
260 }
261 
262 ComplexPairTy ComplexExprEmitter::VisitStmtExpr(const StmtExpr *E) {
263   return CGF.EmitCompoundStmt(*E->getSubStmt(), true).getComplexVal();
264 }
265 
266 /// EmitComplexToComplexCast - Emit a cast from complex value Val to DestType.
267 ComplexPairTy ComplexExprEmitter::EmitComplexToComplexCast(ComplexPairTy Val,
268                                                            QualType SrcType,
269                                                            QualType DestType) {
270   // Get the src/dest element type.
271   SrcType = SrcType->getAsComplexType()->getElementType();
272   DestType = DestType->getAsComplexType()->getElementType();
273 
274   // C99 6.3.1.6: When a value of complex type is converted to another
275   // complex type, both the real and imaginary parts follow the conversion
276   // rules for the corresponding real types.
277   Val.first = CGF.EmitScalarConversion(Val.first, SrcType, DestType);
278   Val.second = CGF.EmitScalarConversion(Val.second, SrcType, DestType);
279   return Val;
280 }
281 
282 ComplexPairTy ComplexExprEmitter::EmitCast(Expr *Op, QualType DestTy) {
283   // Two cases here: cast from (complex to complex) and (scalar to complex).
284   if (Op->getType()->isAnyComplexType())
285     return EmitComplexToComplexCast(Visit(Op), Op->getType(), DestTy);
286 
287   // C99 6.3.1.7: When a value of real type is converted to a complex type, the
288   // real part of the complex  result value is determined by the rules of
289   // conversion to the corresponding real type and the imaginary part of the
290   // complex result value is a positive zero or an unsigned zero.
291   llvm::Value *Elt = CGF.EmitScalarExpr(Op);
292 
293   // Convert the input element to the element type of the complex.
294   DestTy = DestTy->getAsComplexType()->getElementType();
295   Elt = CGF.EmitScalarConversion(Elt, Op->getType(), DestTy);
296 
297   // Return (realval, 0).
298   return ComplexPairTy(Elt, llvm::Constant::getNullValue(Elt->getType()));
299 }
300 
301 ComplexPairTy ComplexExprEmitter::VisitPrePostIncDec(const UnaryOperator *E,
302                                                      bool isInc, bool isPre) {
303   LValue LV = CGF.EmitLValue(E->getSubExpr());
304   // FIXME: Handle volatile!
305   ComplexPairTy InVal = EmitLoadOfComplex(LV.getAddress(), false);
306 
307   uint64_t AmountVal = isInc ? 1 : -1;
308 
309   llvm::Value *NextVal;
310   if (isa<llvm::IntegerType>(InVal.first->getType()))
311     NextVal = llvm::ConstantInt::get(InVal.first->getType(), AmountVal);
312   else if (InVal.first->getType() == llvm::Type::FloatTy)
313     // FIXME: Handle long double.
314     NextVal =
315       llvm::ConstantFP::get(llvm::APFloat(static_cast<float>(AmountVal)));
316   else {
317     // FIXME: Handle long double.
318     assert(InVal.first->getType() == llvm::Type::DoubleTy);
319     NextVal =
320       llvm::ConstantFP::get(llvm::APFloat(static_cast<double>(AmountVal)));
321   }
322 
323   // Add the inc/dec to the real part.
324   NextVal = Builder.CreateAdd(InVal.first, NextVal, isInc ? "inc" : "dec");
325 
326   ComplexPairTy IncVal(NextVal, InVal.second);
327 
328   // Store the updated result through the lvalue.
329   EmitStoreOfComplex(IncVal, LV.getAddress(), false);  /* FIXME: Volatile */
330 
331   // If this is a postinc, return the value read from memory, otherwise use the
332   // updated value.
333   return isPre ? IncVal : InVal;
334 }
335 
336 ComplexPairTy ComplexExprEmitter::VisitUnaryMinus(const UnaryOperator *E) {
337   ComplexPairTy Op = Visit(E->getSubExpr());
338   llvm::Value *ResR = Builder.CreateNeg(Op.first,  "neg.r");
339   llvm::Value *ResI = Builder.CreateNeg(Op.second, "neg.i");
340   return ComplexPairTy(ResR, ResI);
341 }
342 
343 ComplexPairTy ComplexExprEmitter::VisitUnaryNot(const UnaryOperator *E) {
344   // ~(a+ib) = a + i*-b
345   ComplexPairTy Op = Visit(E->getSubExpr());
346   llvm::Value *ResI = Builder.CreateNeg(Op.second, "conj.i");
347   return ComplexPairTy(Op.first, ResI);
348 }
349 
350 ComplexPairTy ComplexExprEmitter::EmitBinAdd(const BinOpInfo &Op) {
351   llvm::Value *ResR = Builder.CreateAdd(Op.LHS.first,  Op.RHS.first,  "add.r");
352   llvm::Value *ResI = Builder.CreateAdd(Op.LHS.second, Op.RHS.second, "add.i");
353   return ComplexPairTy(ResR, ResI);
354 }
355 
356 ComplexPairTy ComplexExprEmitter::EmitBinSub(const BinOpInfo &Op) {
357   llvm::Value *ResR = Builder.CreateSub(Op.LHS.first,  Op.RHS.first,  "sub.r");
358   llvm::Value *ResI = Builder.CreateSub(Op.LHS.second, Op.RHS.second, "sub.i");
359   return ComplexPairTy(ResR, ResI);
360 }
361 
362 
363 ComplexPairTy ComplexExprEmitter::EmitBinMul(const BinOpInfo &Op) {
364   llvm::Value *ResRl = Builder.CreateMul(Op.LHS.first, Op.RHS.first, "mul.rl");
365   llvm::Value *ResRr = Builder.CreateMul(Op.LHS.second, Op.RHS.second,"mul.rr");
366   llvm::Value *ResR  = Builder.CreateSub(ResRl, ResRr, "mul.r");
367 
368   llvm::Value *ResIl = Builder.CreateMul(Op.LHS.second, Op.RHS.first, "mul.il");
369   llvm::Value *ResIr = Builder.CreateMul(Op.LHS.first, Op.RHS.second, "mul.ir");
370   llvm::Value *ResI  = Builder.CreateAdd(ResIl, ResIr, "mul.i");
371   return ComplexPairTy(ResR, ResI);
372 }
373 
374 ComplexPairTy ComplexExprEmitter::EmitBinDiv(const BinOpInfo &Op) {
375   llvm::Value *LHSr = Op.LHS.first, *LHSi = Op.LHS.second;
376   llvm::Value *RHSr = Op.RHS.first, *RHSi = Op.RHS.second;
377 
378   // (a+ib) / (c+id) = ((ac+bd)/(cc+dd)) + i((bc-ad)/(cc+dd))
379   llvm::Value *Tmp1 = Builder.CreateMul(LHSr, RHSr, "tmp"); // a*c
380   llvm::Value *Tmp2 = Builder.CreateMul(LHSi, RHSi, "tmp"); // b*d
381   llvm::Value *Tmp3 = Builder.CreateAdd(Tmp1, Tmp2, "tmp"); // ac+bd
382 
383   llvm::Value *Tmp4 = Builder.CreateMul(RHSr, RHSr, "tmp"); // c*c
384   llvm::Value *Tmp5 = Builder.CreateMul(RHSi, RHSi, "tmp"); // d*d
385   llvm::Value *Tmp6 = Builder.CreateAdd(Tmp4, Tmp5, "tmp"); // cc+dd
386 
387   llvm::Value *Tmp7 = Builder.CreateMul(LHSi, RHSr, "tmp"); // b*c
388   llvm::Value *Tmp8 = Builder.CreateMul(LHSr, RHSi, "tmp"); // a*d
389   llvm::Value *Tmp9 = Builder.CreateSub(Tmp7, Tmp8, "tmp"); // bc-ad
390 
391   llvm::Value *DSTr, *DSTi;
392   if (Tmp3->getType()->isFloatingPoint()) {
393     DSTr = Builder.CreateFDiv(Tmp3, Tmp6, "tmp");
394     DSTi = Builder.CreateFDiv(Tmp9, Tmp6, "tmp");
395   } else {
396     if (Op.Ty->getAsComplexType()->getElementType()->isUnsignedIntegerType()) {
397       DSTr = Builder.CreateUDiv(Tmp3, Tmp6, "tmp");
398       DSTi = Builder.CreateUDiv(Tmp9, Tmp6, "tmp");
399     } else {
400       DSTr = Builder.CreateSDiv(Tmp3, Tmp6, "tmp");
401       DSTi = Builder.CreateSDiv(Tmp9, Tmp6, "tmp");
402     }
403   }
404 
405   return ComplexPairTy(DSTr, DSTi);
406 }
407 
408 ComplexExprEmitter::BinOpInfo
409 ComplexExprEmitter::EmitBinOps(const BinaryOperator *E) {
410   BinOpInfo Ops;
411   Ops.LHS = Visit(E->getLHS());
412   Ops.RHS = Visit(E->getRHS());
413   Ops.Ty = E->getType();
414   return Ops;
415 }
416 
417 
418 // Compound assignments.
419 ComplexPairTy ComplexExprEmitter::
420 EmitCompoundAssign(const CompoundAssignOperator *E,
421                    ComplexPairTy (ComplexExprEmitter::*Func)(const BinOpInfo&)){
422   QualType LHSTy = E->getLHS()->getType(), RHSTy = E->getRHS()->getType();
423 
424   // Load the LHS and RHS operands.
425   LValue LHSLV = CGF.EmitLValue(E->getLHS());
426 
427   BinOpInfo OpInfo;
428   OpInfo.Ty = E->getComputationType();
429 
430   // We know the LHS is a complex lvalue.
431   OpInfo.LHS = EmitLoadOfComplex(LHSLV.getAddress(), false);// FIXME: Volatile.
432   OpInfo.LHS = EmitComplexToComplexCast(OpInfo.LHS, LHSTy, OpInfo.Ty);
433 
434   // It is possible for the RHS to be complex or scalar.
435   OpInfo.RHS = EmitCast(E->getRHS(), OpInfo.Ty);
436 
437   // Expand the binary operator.
438   ComplexPairTy Result = (this->*Func)(OpInfo);
439 
440   // Truncate the result back to the LHS type.
441   Result = EmitComplexToComplexCast(Result, OpInfo.Ty, LHSTy);
442 
443   // Store the result value into the LHS lvalue.
444   EmitStoreOfComplex(Result, LHSLV.getAddress(), false); // FIXME: VOLATILE
445   return Result;
446 }
447 
448 ComplexPairTy ComplexExprEmitter::VisitBinAssign(const BinaryOperator *E) {
449   assert(CGF.getContext().getCanonicalType(E->getLHS()->getType()) ==
450          CGF.getContext().getCanonicalType(E->getRHS()->getType()) &&
451          "Invalid assignment");
452   // Emit the RHS.
453   ComplexPairTy Val = Visit(E->getRHS());
454 
455   // Compute the address to store into.
456   LValue LHS = CGF.EmitLValue(E->getLHS());
457 
458   // Store into it.
459   // FIXME: Volatility!
460   EmitStoreOfComplex(Val, LHS.getAddress(), false);
461   return Val;
462 }
463 
464 ComplexPairTy ComplexExprEmitter::VisitBinComma(const BinaryOperator *E) {
465   CGF.EmitStmt(E->getLHS());
466   CGF.EnsureInsertPoint();
467   return Visit(E->getRHS());
468 }
469 
470 ComplexPairTy ComplexExprEmitter::
471 VisitConditionalOperator(const ConditionalOperator *E) {
472   llvm::BasicBlock *LHSBlock = CGF.createBasicBlock("cond.true");
473   llvm::BasicBlock *RHSBlock = CGF.createBasicBlock("cond.false");
474   llvm::BasicBlock *ContBlock = CGF.createBasicBlock("cond.end");
475 
476   llvm::Value *Cond = CGF.EvaluateExprAsBool(E->getCond());
477   Builder.CreateCondBr(Cond, LHSBlock, RHSBlock);
478 
479   CGF.EmitBlock(LHSBlock);
480 
481   // Handle the GNU extension for missing LHS.
482   assert(E->getLHS() && "Must have LHS for complex value");
483 
484   ComplexPairTy LHS = Visit(E->getLHS());
485   LHSBlock = Builder.GetInsertBlock();
486   CGF.EmitBranch(ContBlock);
487 
488   CGF.EmitBlock(RHSBlock);
489 
490   ComplexPairTy RHS = Visit(E->getRHS());
491   RHSBlock = Builder.GetInsertBlock();
492   CGF.EmitBranch(ContBlock);
493 
494   CGF.EmitBlock(ContBlock);
495 
496   // Create a PHI node for the real part.
497   llvm::PHINode *RealPN = Builder.CreatePHI(LHS.first->getType(), "cond.r");
498   RealPN->reserveOperandSpace(2);
499   RealPN->addIncoming(LHS.first, LHSBlock);
500   RealPN->addIncoming(RHS.first, RHSBlock);
501 
502   // Create a PHI node for the imaginary part.
503   llvm::PHINode *ImagPN = Builder.CreatePHI(LHS.first->getType(), "cond.i");
504   ImagPN->reserveOperandSpace(2);
505   ImagPN->addIncoming(LHS.second, LHSBlock);
506   ImagPN->addIncoming(RHS.second, RHSBlock);
507 
508   return ComplexPairTy(RealPN, ImagPN);
509 }
510 
511 ComplexPairTy ComplexExprEmitter::VisitChooseExpr(ChooseExpr *E) {
512   return Visit(E->getChosenSubExpr(CGF.getContext()));
513 }
514 
515 ComplexPairTy ComplexExprEmitter::VisitInitListExpr(InitListExpr *E) {
516   if (E->getNumInits())
517     return Visit(E->getInit(0));
518 
519   // Empty init list intializes to null
520   QualType Ty = E->getType()->getAsComplexType()->getElementType();
521   const llvm::Type* LTy = CGF.ConvertType(Ty);
522   llvm::Value* zeroConstant = llvm::Constant::getNullValue(LTy);
523   return ComplexPairTy(zeroConstant, zeroConstant);
524 }
525 
526 ComplexPairTy ComplexExprEmitter::VisitVAArgExpr(VAArgExpr *E) {
527   llvm::Value *ArgValue = CGF.EmitVAListRef(E->getSubExpr());
528   llvm::Value *ArgPtr = CGF.EmitVAArg(ArgValue, E->getType());
529 
530   if (!ArgPtr) {
531     CGF.ErrorUnsupported(E, "complex va_arg expression");
532     const llvm::Type *EltTy =
533       CGF.ConvertType(E->getType()->getAsComplexType()->getElementType());
534     llvm::Value *U = llvm::UndefValue::get(EltTy);
535     return ComplexPairTy(U, U);
536   }
537 
538   // FIXME Volatility.
539   return EmitLoadOfComplex(ArgPtr, false);
540 }
541 
542 //===----------------------------------------------------------------------===//
543 //                         Entry Point into this File
544 //===----------------------------------------------------------------------===//
545 
546 /// EmitComplexExpr - Emit the computation of the specified expression of
547 /// complex type, ignoring the result.
548 ComplexPairTy CodeGenFunction::EmitComplexExpr(const Expr *E) {
549   assert(E && E->getType()->isAnyComplexType() &&
550          "Invalid complex expression to emit");
551 
552   return ComplexExprEmitter(*this).Visit(const_cast<Expr*>(E));
553 }
554 
555 /// EmitComplexExprIntoAddr - Emit the computation of the specified expression
556 /// of complex type, storing into the specified Value*.
557 void CodeGenFunction::EmitComplexExprIntoAddr(const Expr *E,
558                                               llvm::Value *DestAddr,
559                                               bool DestIsVolatile) {
560   assert(E && E->getType()->isAnyComplexType() &&
561          "Invalid complex expression to emit");
562   ComplexExprEmitter Emitter(*this);
563   ComplexPairTy Val = Emitter.Visit(const_cast<Expr*>(E));
564   Emitter.EmitStoreOfComplex(Val, DestAddr, DestIsVolatile);
565 }
566 
567 /// StoreComplexToAddr - Store a complex number into the specified address.
568 void CodeGenFunction::StoreComplexToAddr(ComplexPairTy V,
569                                          llvm::Value *DestAddr,
570                                          bool DestIsVolatile) {
571   ComplexExprEmitter(*this).EmitStoreOfComplex(V, DestAddr, DestIsVolatile);
572 }
573 
574 /// LoadComplexFromAddr - Load a complex number from the specified address.
575 ComplexPairTy CodeGenFunction::LoadComplexFromAddr(llvm::Value *SrcAddr,
576                                                    bool SrcIsVolatile) {
577   return ComplexExprEmitter(*this).EmitLoadOfComplex(SrcAddr, SrcIsVolatile);
578 }
579