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   ComplexPairTy VisitImplicitValueInitExpr(ImplicitValueInitExpr *E) {
134     assert(E->getType()->isAnyComplexType() && "Expected complex type!");
135     QualType Elem = E->getType()->getAsComplexType()->getElementType();
136     llvm::Constant *Null = llvm::Constant::getNullValue(CGF.ConvertType(Elem));
137     return ComplexPairTy(Null, Null);
138   }
139 
140   struct BinOpInfo {
141     ComplexPairTy LHS;
142     ComplexPairTy RHS;
143     QualType Ty;  // Computation Type.
144   };
145 
146   BinOpInfo EmitBinOps(const BinaryOperator *E);
147   ComplexPairTy EmitCompoundAssign(const CompoundAssignOperator *E,
148                                    ComplexPairTy (ComplexExprEmitter::*Func)
149                                    (const BinOpInfo &));
150 
151   ComplexPairTy EmitBinAdd(const BinOpInfo &Op);
152   ComplexPairTy EmitBinSub(const BinOpInfo &Op);
153   ComplexPairTy EmitBinMul(const BinOpInfo &Op);
154   ComplexPairTy EmitBinDiv(const BinOpInfo &Op);
155 
156   ComplexPairTy VisitBinMul(const BinaryOperator *E) {
157     return EmitBinMul(EmitBinOps(E));
158   }
159   ComplexPairTy VisitBinAdd(const BinaryOperator *E) {
160     return EmitBinAdd(EmitBinOps(E));
161   }
162   ComplexPairTy VisitBinSub(const BinaryOperator *E) {
163     return EmitBinSub(EmitBinOps(E));
164   }
165   ComplexPairTy VisitBinDiv(const BinaryOperator *E) {
166     return EmitBinDiv(EmitBinOps(E));
167   }
168 
169   // Compound assignments.
170   ComplexPairTy VisitBinAddAssign(const CompoundAssignOperator *E) {
171     return EmitCompoundAssign(E, &ComplexExprEmitter::EmitBinAdd);
172   }
173   ComplexPairTy VisitBinSubAssign(const CompoundAssignOperator *E) {
174     return EmitCompoundAssign(E, &ComplexExprEmitter::EmitBinSub);
175   }
176   ComplexPairTy VisitBinMulAssign(const CompoundAssignOperator *E) {
177     return EmitCompoundAssign(E, &ComplexExprEmitter::EmitBinMul);
178   }
179   ComplexPairTy VisitBinDivAssign(const CompoundAssignOperator *E) {
180     return EmitCompoundAssign(E, &ComplexExprEmitter::EmitBinDiv);
181   }
182 
183   // GCC rejects rem/and/or/xor for integer complex.
184   // Logical and/or always return int, never complex.
185 
186   // No comparisons produce a complex result.
187   ComplexPairTy VisitBinAssign     (const BinaryOperator *E);
188   ComplexPairTy VisitBinComma      (const BinaryOperator *E);
189 
190 
191   ComplexPairTy VisitConditionalOperator(const ConditionalOperator *CO);
192   ComplexPairTy VisitChooseExpr(ChooseExpr *CE);
193 
194   ComplexPairTy VisitInitListExpr(InitListExpr *E);
195 
196   ComplexPairTy VisitVAArgExpr(VAArgExpr *E);
197 };
198 }  // end anonymous namespace.
199 
200 //===----------------------------------------------------------------------===//
201 //                                Utilities
202 //===----------------------------------------------------------------------===//
203 
204 /// EmitLoadOfComplex - Given an RValue reference for a complex, emit code to
205 /// load the real and imaginary pieces, returning them as Real/Imag.
206 ComplexPairTy ComplexExprEmitter::EmitLoadOfComplex(llvm::Value *SrcPtr,
207                                                     bool isVolatile) {
208   llvm::SmallString<64> Name(SrcPtr->getNameStart(),
209                              SrcPtr->getNameStart()+SrcPtr->getNameLen());
210 
211   Name += ".realp";
212   llvm::Value *RealPtr = Builder.CreateStructGEP(SrcPtr, 0, Name.c_str());
213 
214   Name.pop_back();  // .realp -> .real
215   llvm::Value *Real = Builder.CreateLoad(RealPtr, isVolatile, Name.c_str());
216 
217   Name.resize(Name.size()-4); // .real -> .imagp
218   Name += "imagp";
219 
220   llvm::Value *ImagPtr = Builder.CreateStructGEP(SrcPtr, 1, Name.c_str());
221 
222   Name.pop_back();  // .imagp -> .imag
223   llvm::Value *Imag = Builder.CreateLoad(ImagPtr, isVolatile, Name.c_str());
224   return ComplexPairTy(Real, Imag);
225 }
226 
227 /// EmitStoreOfComplex - Store the specified real/imag parts into the
228 /// specified value pointer.
229 void ComplexExprEmitter::EmitStoreOfComplex(ComplexPairTy Val, llvm::Value *Ptr,
230                                             bool isVolatile) {
231   llvm::Value *RealPtr = Builder.CreateStructGEP(Ptr, 0, "real");
232   llvm::Value *ImagPtr = Builder.CreateStructGEP(Ptr, 1, "imag");
233 
234   Builder.CreateStore(Val.first, RealPtr, isVolatile);
235   Builder.CreateStore(Val.second, ImagPtr, isVolatile);
236 }
237 
238 
239 
240 //===----------------------------------------------------------------------===//
241 //                            Visitor Methods
242 //===----------------------------------------------------------------------===//
243 
244 ComplexPairTy ComplexExprEmitter::VisitExpr(Expr *E) {
245   CGF.ErrorUnsupported(E, "complex expression");
246   const llvm::Type *EltTy =
247     CGF.ConvertType(E->getType()->getAsComplexType()->getElementType());
248   llvm::Value *U = llvm::UndefValue::get(EltTy);
249   return ComplexPairTy(U, U);
250 }
251 
252 ComplexPairTy ComplexExprEmitter::
253 VisitImaginaryLiteral(const ImaginaryLiteral *IL) {
254   llvm::Value *Imag = CGF.EmitScalarExpr(IL->getSubExpr());
255   return ComplexPairTy(llvm::Constant::getNullValue(Imag->getType()), Imag);
256 }
257 
258 
259 ComplexPairTy ComplexExprEmitter::VisitCallExpr(const CallExpr *E) {
260   return CGF.EmitCallExpr(E).getComplexVal();
261 }
262 
263 ComplexPairTy ComplexExprEmitter::VisitOverloadExpr(const OverloadExpr *E) {
264   return CGF.EmitCallExpr(E->getFn(), E->arg_begin(),
265                           E->arg_end(CGF.getContext())).getComplexVal();
266 }
267 
268 ComplexPairTy ComplexExprEmitter::VisitStmtExpr(const StmtExpr *E) {
269   return CGF.EmitCompoundStmt(*E->getSubStmt(), true).getComplexVal();
270 }
271 
272 /// EmitComplexToComplexCast - Emit a cast from complex value Val to DestType.
273 ComplexPairTy ComplexExprEmitter::EmitComplexToComplexCast(ComplexPairTy Val,
274                                                            QualType SrcType,
275                                                            QualType DestType) {
276   // Get the src/dest element type.
277   SrcType = SrcType->getAsComplexType()->getElementType();
278   DestType = DestType->getAsComplexType()->getElementType();
279 
280   // C99 6.3.1.6: When a value of complex type is converted to another
281   // complex type, both the real and imaginary parts follow the conversion
282   // rules for the corresponding real types.
283   Val.first = CGF.EmitScalarConversion(Val.first, SrcType, DestType);
284   Val.second = CGF.EmitScalarConversion(Val.second, SrcType, DestType);
285   return Val;
286 }
287 
288 ComplexPairTy ComplexExprEmitter::EmitCast(Expr *Op, QualType DestTy) {
289   // Two cases here: cast from (complex to complex) and (scalar to complex).
290   if (Op->getType()->isAnyComplexType())
291     return EmitComplexToComplexCast(Visit(Op), Op->getType(), DestTy);
292 
293   // C99 6.3.1.7: When a value of real type is converted to a complex type, the
294   // real part of the complex  result value is determined by the rules of
295   // conversion to the corresponding real type and the imaginary part of the
296   // complex result value is a positive zero or an unsigned zero.
297   llvm::Value *Elt = CGF.EmitScalarExpr(Op);
298 
299   // Convert the input element to the element type of the complex.
300   DestTy = DestTy->getAsComplexType()->getElementType();
301   Elt = CGF.EmitScalarConversion(Elt, Op->getType(), DestTy);
302 
303   // Return (realval, 0).
304   return ComplexPairTy(Elt, llvm::Constant::getNullValue(Elt->getType()));
305 }
306 
307 ComplexPairTy ComplexExprEmitter::VisitPrePostIncDec(const UnaryOperator *E,
308                                                      bool isInc, bool isPre) {
309   LValue LV = CGF.EmitLValue(E->getSubExpr());
310   // FIXME: Handle volatile!
311   ComplexPairTy InVal = EmitLoadOfComplex(LV.getAddress(), false);
312 
313   uint64_t AmountVal = isInc ? 1 : -1;
314 
315   llvm::Value *NextVal;
316   if (isa<llvm::IntegerType>(InVal.first->getType()))
317     NextVal = llvm::ConstantInt::get(InVal.first->getType(), AmountVal);
318   else if (InVal.first->getType() == llvm::Type::FloatTy)
319     // FIXME: Handle long double.
320     NextVal =
321       llvm::ConstantFP::get(llvm::APFloat(static_cast<float>(AmountVal)));
322   else {
323     // FIXME: Handle long double.
324     assert(InVal.first->getType() == llvm::Type::DoubleTy);
325     NextVal =
326       llvm::ConstantFP::get(llvm::APFloat(static_cast<double>(AmountVal)));
327   }
328 
329   // Add the inc/dec to the real part.
330   NextVal = Builder.CreateAdd(InVal.first, NextVal, isInc ? "inc" : "dec");
331 
332   ComplexPairTy IncVal(NextVal, InVal.second);
333 
334   // Store the updated result through the lvalue.
335   EmitStoreOfComplex(IncVal, LV.getAddress(), false);  /* FIXME: Volatile */
336 
337   // If this is a postinc, return the value read from memory, otherwise use the
338   // updated value.
339   return isPre ? IncVal : InVal;
340 }
341 
342 ComplexPairTy ComplexExprEmitter::VisitUnaryMinus(const UnaryOperator *E) {
343   ComplexPairTy Op = Visit(E->getSubExpr());
344   llvm::Value *ResR = Builder.CreateNeg(Op.first,  "neg.r");
345   llvm::Value *ResI = Builder.CreateNeg(Op.second, "neg.i");
346   return ComplexPairTy(ResR, ResI);
347 }
348 
349 ComplexPairTy ComplexExprEmitter::VisitUnaryNot(const UnaryOperator *E) {
350   // ~(a+ib) = a + i*-b
351   ComplexPairTy Op = Visit(E->getSubExpr());
352   llvm::Value *ResI = Builder.CreateNeg(Op.second, "conj.i");
353   return ComplexPairTy(Op.first, ResI);
354 }
355 
356 ComplexPairTy ComplexExprEmitter::EmitBinAdd(const BinOpInfo &Op) {
357   llvm::Value *ResR = Builder.CreateAdd(Op.LHS.first,  Op.RHS.first,  "add.r");
358   llvm::Value *ResI = Builder.CreateAdd(Op.LHS.second, Op.RHS.second, "add.i");
359   return ComplexPairTy(ResR, ResI);
360 }
361 
362 ComplexPairTy ComplexExprEmitter::EmitBinSub(const BinOpInfo &Op) {
363   llvm::Value *ResR = Builder.CreateSub(Op.LHS.first,  Op.RHS.first,  "sub.r");
364   llvm::Value *ResI = Builder.CreateSub(Op.LHS.second, Op.RHS.second, "sub.i");
365   return ComplexPairTy(ResR, ResI);
366 }
367 
368 
369 ComplexPairTy ComplexExprEmitter::EmitBinMul(const BinOpInfo &Op) {
370   llvm::Value *ResRl = Builder.CreateMul(Op.LHS.first, Op.RHS.first, "mul.rl");
371   llvm::Value *ResRr = Builder.CreateMul(Op.LHS.second, Op.RHS.second,"mul.rr");
372   llvm::Value *ResR  = Builder.CreateSub(ResRl, ResRr, "mul.r");
373 
374   llvm::Value *ResIl = Builder.CreateMul(Op.LHS.second, Op.RHS.first, "mul.il");
375   llvm::Value *ResIr = Builder.CreateMul(Op.LHS.first, Op.RHS.second, "mul.ir");
376   llvm::Value *ResI  = Builder.CreateAdd(ResIl, ResIr, "mul.i");
377   return ComplexPairTy(ResR, ResI);
378 }
379 
380 ComplexPairTy ComplexExprEmitter::EmitBinDiv(const BinOpInfo &Op) {
381   llvm::Value *LHSr = Op.LHS.first, *LHSi = Op.LHS.second;
382   llvm::Value *RHSr = Op.RHS.first, *RHSi = Op.RHS.second;
383 
384   // (a+ib) / (c+id) = ((ac+bd)/(cc+dd)) + i((bc-ad)/(cc+dd))
385   llvm::Value *Tmp1 = Builder.CreateMul(LHSr, RHSr, "tmp"); // a*c
386   llvm::Value *Tmp2 = Builder.CreateMul(LHSi, RHSi, "tmp"); // b*d
387   llvm::Value *Tmp3 = Builder.CreateAdd(Tmp1, Tmp2, "tmp"); // ac+bd
388 
389   llvm::Value *Tmp4 = Builder.CreateMul(RHSr, RHSr, "tmp"); // c*c
390   llvm::Value *Tmp5 = Builder.CreateMul(RHSi, RHSi, "tmp"); // d*d
391   llvm::Value *Tmp6 = Builder.CreateAdd(Tmp4, Tmp5, "tmp"); // cc+dd
392 
393   llvm::Value *Tmp7 = Builder.CreateMul(LHSi, RHSr, "tmp"); // b*c
394   llvm::Value *Tmp8 = Builder.CreateMul(LHSr, RHSi, "tmp"); // a*d
395   llvm::Value *Tmp9 = Builder.CreateSub(Tmp7, Tmp8, "tmp"); // bc-ad
396 
397   llvm::Value *DSTr, *DSTi;
398   if (Tmp3->getType()->isFloatingPoint()) {
399     DSTr = Builder.CreateFDiv(Tmp3, Tmp6, "tmp");
400     DSTi = Builder.CreateFDiv(Tmp9, Tmp6, "tmp");
401   } else {
402     if (Op.Ty->getAsComplexType()->getElementType()->isUnsignedIntegerType()) {
403       DSTr = Builder.CreateUDiv(Tmp3, Tmp6, "tmp");
404       DSTi = Builder.CreateUDiv(Tmp9, Tmp6, "tmp");
405     } else {
406       DSTr = Builder.CreateSDiv(Tmp3, Tmp6, "tmp");
407       DSTi = Builder.CreateSDiv(Tmp9, Tmp6, "tmp");
408     }
409   }
410 
411   return ComplexPairTy(DSTr, DSTi);
412 }
413 
414 ComplexExprEmitter::BinOpInfo
415 ComplexExprEmitter::EmitBinOps(const BinaryOperator *E) {
416   BinOpInfo Ops;
417   Ops.LHS = Visit(E->getLHS());
418   Ops.RHS = Visit(E->getRHS());
419   Ops.Ty = E->getType();
420   return Ops;
421 }
422 
423 
424 // Compound assignments.
425 ComplexPairTy ComplexExprEmitter::
426 EmitCompoundAssign(const CompoundAssignOperator *E,
427                    ComplexPairTy (ComplexExprEmitter::*Func)(const BinOpInfo&)){
428   QualType LHSTy = E->getLHS()->getType(), RHSTy = E->getRHS()->getType();
429 
430   // Load the LHS and RHS operands.
431   LValue LHSLV = CGF.EmitLValue(E->getLHS());
432 
433   BinOpInfo OpInfo;
434   OpInfo.Ty = E->getComputationType();
435 
436   // We know the LHS is a complex lvalue.
437   OpInfo.LHS = EmitLoadOfComplex(LHSLV.getAddress(), false);// FIXME: Volatile.
438   OpInfo.LHS = EmitComplexToComplexCast(OpInfo.LHS, LHSTy, OpInfo.Ty);
439 
440   // It is possible for the RHS to be complex or scalar.
441   OpInfo.RHS = EmitCast(E->getRHS(), OpInfo.Ty);
442 
443   // Expand the binary operator.
444   ComplexPairTy Result = (this->*Func)(OpInfo);
445 
446   // Truncate the result back to the LHS type.
447   Result = EmitComplexToComplexCast(Result, OpInfo.Ty, LHSTy);
448 
449   // Store the result value into the LHS lvalue.
450   EmitStoreOfComplex(Result, LHSLV.getAddress(), false); // FIXME: VOLATILE
451   return Result;
452 }
453 
454 ComplexPairTy ComplexExprEmitter::VisitBinAssign(const BinaryOperator *E) {
455   assert(CGF.getContext().getCanonicalType(E->getLHS()->getType()) ==
456          CGF.getContext().getCanonicalType(E->getRHS()->getType()) &&
457          "Invalid assignment");
458   // Emit the RHS.
459   ComplexPairTy Val = Visit(E->getRHS());
460 
461   // Compute the address to store into.
462   LValue LHS = CGF.EmitLValue(E->getLHS());
463 
464   // Store into it.
465   // FIXME: Volatility!
466   EmitStoreOfComplex(Val, LHS.getAddress(), false);
467   return Val;
468 }
469 
470 ComplexPairTy ComplexExprEmitter::VisitBinComma(const BinaryOperator *E) {
471   CGF.EmitStmt(E->getLHS());
472   CGF.EnsureInsertPoint();
473   return Visit(E->getRHS());
474 }
475 
476 ComplexPairTy ComplexExprEmitter::
477 VisitConditionalOperator(const ConditionalOperator *E) {
478   llvm::BasicBlock *LHSBlock = CGF.createBasicBlock("cond.true");
479   llvm::BasicBlock *RHSBlock = CGF.createBasicBlock("cond.false");
480   llvm::BasicBlock *ContBlock = CGF.createBasicBlock("cond.end");
481 
482   llvm::Value *Cond = CGF.EvaluateExprAsBool(E->getCond());
483   Builder.CreateCondBr(Cond, LHSBlock, RHSBlock);
484 
485   CGF.EmitBlock(LHSBlock);
486 
487   // Handle the GNU extension for missing LHS.
488   assert(E->getLHS() && "Must have LHS for complex value");
489 
490   ComplexPairTy LHS = Visit(E->getLHS());
491   LHSBlock = Builder.GetInsertBlock();
492   CGF.EmitBranch(ContBlock);
493 
494   CGF.EmitBlock(RHSBlock);
495 
496   ComplexPairTy RHS = Visit(E->getRHS());
497   RHSBlock = Builder.GetInsertBlock();
498   CGF.EmitBranch(ContBlock);
499 
500   CGF.EmitBlock(ContBlock);
501 
502   // Create a PHI node for the real part.
503   llvm::PHINode *RealPN = Builder.CreatePHI(LHS.first->getType(), "cond.r");
504   RealPN->reserveOperandSpace(2);
505   RealPN->addIncoming(LHS.first, LHSBlock);
506   RealPN->addIncoming(RHS.first, RHSBlock);
507 
508   // Create a PHI node for the imaginary part.
509   llvm::PHINode *ImagPN = Builder.CreatePHI(LHS.first->getType(), "cond.i");
510   ImagPN->reserveOperandSpace(2);
511   ImagPN->addIncoming(LHS.second, LHSBlock);
512   ImagPN->addIncoming(RHS.second, RHSBlock);
513 
514   return ComplexPairTy(RealPN, ImagPN);
515 }
516 
517 ComplexPairTy ComplexExprEmitter::VisitChooseExpr(ChooseExpr *E) {
518   // Emit the LHS or RHS as appropriate.
519   return Visit(E->isConditionTrue(CGF.getContext()) ? E->getLHS() :E->getRHS());
520 }
521 
522 ComplexPairTy ComplexExprEmitter::VisitInitListExpr(InitListExpr *E) {
523   if (E->getNumInits())
524     return Visit(E->getInit(0));
525 
526   // Empty init list intializes to null
527   QualType Ty = E->getType()->getAsComplexType()->getElementType();
528   const llvm::Type* LTy = CGF.ConvertType(Ty);
529   llvm::Value* zeroConstant = llvm::Constant::getNullValue(LTy);
530   return ComplexPairTy(zeroConstant, zeroConstant);
531 }
532 
533 ComplexPairTy ComplexExprEmitter::VisitVAArgExpr(VAArgExpr *E) {
534   llvm::Value *ArgValue = CGF.EmitVAListRef(E->getSubExpr());
535   llvm::Value *ArgPtr = CGF.EmitVAArg(ArgValue, E->getType());
536 
537   if (!ArgPtr) {
538     CGF.ErrorUnsupported(E, "complex va_arg expression");
539     const llvm::Type *EltTy =
540       CGF.ConvertType(E->getType()->getAsComplexType()->getElementType());
541     llvm::Value *U = llvm::UndefValue::get(EltTy);
542     return ComplexPairTy(U, U);
543   }
544 
545   // FIXME Volatility.
546   return EmitLoadOfComplex(ArgPtr, false);
547 }
548 
549 //===----------------------------------------------------------------------===//
550 //                         Entry Point into this File
551 //===----------------------------------------------------------------------===//
552 
553 /// EmitComplexExpr - Emit the computation of the specified expression of
554 /// complex type, ignoring the result.
555 ComplexPairTy CodeGenFunction::EmitComplexExpr(const Expr *E) {
556   assert(E && E->getType()->isAnyComplexType() &&
557          "Invalid complex expression to emit");
558 
559   return ComplexExprEmitter(*this).Visit(const_cast<Expr*>(E));
560 }
561 
562 /// EmitComplexExprIntoAddr - Emit the computation of the specified expression
563 /// of complex type, storing into the specified Value*.
564 void CodeGenFunction::EmitComplexExprIntoAddr(const Expr *E,
565                                               llvm::Value *DestAddr,
566                                               bool DestIsVolatile) {
567   assert(E && E->getType()->isAnyComplexType() &&
568          "Invalid complex expression to emit");
569   ComplexExprEmitter Emitter(*this);
570   ComplexPairTy Val = Emitter.Visit(const_cast<Expr*>(E));
571   Emitter.EmitStoreOfComplex(Val, DestAddr, DestIsVolatile);
572 }
573 
574 /// StoreComplexToAddr - Store a complex number into the specified address.
575 void CodeGenFunction::StoreComplexToAddr(ComplexPairTy V,
576                                          llvm::Value *DestAddr,
577                                          bool DestIsVolatile) {
578   ComplexExprEmitter(*this).EmitStoreOfComplex(V, DestAddr, DestIsVolatile);
579 }
580 
581 /// LoadComplexFromAddr - Load a complex number from the specified address.
582 ComplexPairTy CodeGenFunction::LoadComplexFromAddr(llvm::Value *SrcAddr,
583                                                    bool SrcIsVolatile) {
584   return ComplexExprEmitter(*this).EmitLoadOfComplex(SrcAddr, SrcIsVolatile);
585 }
586