CGExprScalar.cpp revision 4ac0d83090c750bd8ab2c4fc91a6a44c32884cb3 
1//===--- CGExprScalar.cpp - Emit LLVM Code for Scalar 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 scalar LLVM types as LLVM code.
11//
12//===----------------------------------------------------------------------===//
13
14#include "CodeGenFunction.h"
15#include "CGObjCRuntime.h"
16#include "CodeGenModule.h"
17#include "clang/AST/ASTContext.h"
18#include "clang/AST/DeclObjC.h"
19#include "clang/AST/RecordLayout.h"
20#include "clang/AST/StmtVisitor.h"
21#include "clang/Basic/TargetInfo.h"
22#include "llvm/Constants.h"
23#include "llvm/Function.h"
24#include "llvm/GlobalVariable.h"
25#include "llvm/Intrinsics.h"
26#include "llvm/Module.h"
27#include "llvm/Support/CFG.h"
28#include "llvm/Target/TargetData.h"
29#include <cstdarg>
30
31using namespace clang;
32using namespace CodeGen;
33using llvm::Value;
34
35//===----------------------------------------------------------------------===//
36//                         Scalar Expression Emitter
37//===----------------------------------------------------------------------===//
38
39struct BinOpInfo {
40  Value *LHS;
41  Value *RHS;
42  QualType Ty;  // Computation Type.
43  BinaryOperator::Opcode Opcode; // Opcode of BinOp to perform
44  const Expr *E;      // Entire expr, for error unsupported.  May not be binop.
45};
46
47namespace {
48class ScalarExprEmitter
49  : public StmtVisitor<ScalarExprEmitter, Value*> {
50  CodeGenFunction &CGF;
51  CGBuilderTy &Builder;
52  bool IgnoreResultAssign;
53  llvm::LLVMContext &VMContext;
54public:
55
56  ScalarExprEmitter(CodeGenFunction &cgf, bool ira=false)
57    : CGF(cgf), Builder(CGF.Builder), IgnoreResultAssign(ira),
58      VMContext(cgf.getLLVMContext()) {
59  }
60
61  //===--------------------------------------------------------------------===//
62  //                               Utilities
63  //===--------------------------------------------------------------------===//
64
65  bool TestAndClearIgnoreResultAssign() {
66    bool I = IgnoreResultAssign;
67    IgnoreResultAssign = false;
68    return I;
69  }
70
71  const llvm::Type *ConvertType(QualType T) { return CGF.ConvertType(T); }
72  LValue EmitLValue(const Expr *E) { return CGF.EmitLValue(E); }
73  LValue EmitCheckedLValue(const Expr *E) { return CGF.EmitCheckedLValue(E); }
74
75  Value *EmitLoadOfLValue(LValue LV, QualType T) {
76    return CGF.EmitLoadOfLValue(LV, T).getScalarVal();
77  }
78
79  /// EmitLoadOfLValue - Given an expression with complex type that represents a
80  /// value l-value, this method emits the address of the l-value, then loads
81  /// and returns the result.
82  Value *EmitLoadOfLValue(const Expr *E) {
83    return EmitLoadOfLValue(EmitCheckedLValue(E), E->getType());
84  }
85
86  /// EmitConversionToBool - Convert the specified expression value to a
87  /// boolean (i1) truth value.  This is equivalent to "Val != 0".
88  Value *EmitConversionToBool(Value *Src, QualType DstTy);
89
90  /// EmitScalarConversion - Emit a conversion from the specified type to the
91  /// specified destination type, both of which are LLVM scalar types.
92  Value *EmitScalarConversion(Value *Src, QualType SrcTy, QualType DstTy);
93
94  /// EmitComplexToScalarConversion - Emit a conversion from the specified
95  /// complex type to the specified destination type, where the destination type
96  /// is an LLVM scalar type.
97  Value *EmitComplexToScalarConversion(CodeGenFunction::ComplexPairTy Src,
98                                       QualType SrcTy, QualType DstTy);
99
100  /// EmitNullValue - Emit a value that corresponds to null for the given type.
101  Value *EmitNullValue(QualType Ty);
102
103  //===--------------------------------------------------------------------===//
104  //                            Visitor Methods
105  //===--------------------------------------------------------------------===//
106
107  Value *VisitStmt(Stmt *S) {
108    S->dump(CGF.getContext().getSourceManager());
109    assert(0 && "Stmt can't have complex result type!");
110    return 0;
111  }
112  Value *VisitExpr(Expr *S);
113
114  Value *VisitParenExpr(ParenExpr *PE) { return Visit(PE->getSubExpr()); }
115
116  // Leaves.
117  Value *VisitIntegerLiteral(const IntegerLiteral *E) {
118    return llvm::ConstantInt::get(VMContext, E->getValue());
119  }
120  Value *VisitFloatingLiteral(const FloatingLiteral *E) {
121    return llvm::ConstantFP::get(VMContext, E->getValue());
122  }
123  Value *VisitCharacterLiteral(const CharacterLiteral *E) {
124    return llvm::ConstantInt::get(ConvertType(E->getType()), E->getValue());
125  }
126  Value *VisitCXXBoolLiteralExpr(const CXXBoolLiteralExpr *E) {
127    return llvm::ConstantInt::get(ConvertType(E->getType()), E->getValue());
128  }
129  Value *VisitCXXZeroInitValueExpr(const CXXZeroInitValueExpr *E) {
130    return EmitNullValue(E->getType());
131  }
132  Value *VisitGNUNullExpr(const GNUNullExpr *E) {
133    return EmitNullValue(E->getType());
134  }
135  Value *VisitTypesCompatibleExpr(const TypesCompatibleExpr *E) {
136    return llvm::ConstantInt::get(ConvertType(E->getType()),
137                                  CGF.getContext().typesAreCompatible(
138                                    E->getArgType1(), E->getArgType2()));
139  }
140  Value *VisitOffsetOfExpr(const OffsetOfExpr *E);
141  Value *VisitSizeOfAlignOfExpr(const SizeOfAlignOfExpr *E);
142  Value *VisitAddrLabelExpr(const AddrLabelExpr *E) {
143    llvm::Value *V = CGF.GetAddrOfLabel(E->getLabel());
144    return Builder.CreateBitCast(V, ConvertType(E->getType()));
145  }
146
147  // l-values.
148  Value *VisitDeclRefExpr(DeclRefExpr *E) {
149    Expr::EvalResult Result;
150    if (E->Evaluate(Result, CGF.getContext()) && Result.Val.isInt()) {
151      assert(!Result.HasSideEffects && "Constant declref with side-effect?!");
152      return llvm::ConstantInt::get(VMContext, Result.Val.getInt());
153    }
154    return EmitLoadOfLValue(E);
155  }
156  Value *VisitObjCSelectorExpr(ObjCSelectorExpr *E) {
157    return CGF.EmitObjCSelectorExpr(E);
158  }
159  Value *VisitObjCProtocolExpr(ObjCProtocolExpr *E) {
160    return CGF.EmitObjCProtocolExpr(E);
161  }
162  Value *VisitObjCIvarRefExpr(ObjCIvarRefExpr *E) {
163    return EmitLoadOfLValue(E);
164  }
165  Value *VisitObjCPropertyRefExpr(ObjCPropertyRefExpr *E) {
166    return EmitLoadOfLValue(E);
167  }
168  Value *VisitObjCImplicitSetterGetterRefExpr(
169                        ObjCImplicitSetterGetterRefExpr *E) {
170    return EmitLoadOfLValue(E);
171  }
172  Value *VisitObjCMessageExpr(ObjCMessageExpr *E) {
173    return CGF.EmitObjCMessageExpr(E).getScalarVal();
174  }
175
176  Value *VisitObjCIsaExpr(ObjCIsaExpr *E) {
177    LValue LV = CGF.EmitObjCIsaExpr(E);
178    Value *V = CGF.EmitLoadOfLValue(LV, E->getType()).getScalarVal();
179    return V;
180  }
181
182  Value *VisitArraySubscriptExpr(ArraySubscriptExpr *E);
183  Value *VisitShuffleVectorExpr(ShuffleVectorExpr *E);
184  Value *VisitMemberExpr(MemberExpr *E);
185  Value *VisitExtVectorElementExpr(Expr *E) { return EmitLoadOfLValue(E); }
186  Value *VisitCompoundLiteralExpr(CompoundLiteralExpr *E) {
187    return EmitLoadOfLValue(E);
188  }
189
190  Value *VisitInitListExpr(InitListExpr *E);
191
192  Value *VisitImplicitValueInitExpr(const ImplicitValueInitExpr *E) {
193    return CGF.CGM.EmitNullConstant(E->getType());
194  }
195  Value *VisitCastExpr(CastExpr *E) {
196    // Make sure to evaluate VLA bounds now so that we have them for later.
197    if (E->getType()->isVariablyModifiedType())
198      CGF.EmitVLASize(E->getType());
199
200    return EmitCastExpr(E);
201  }
202  Value *EmitCastExpr(CastExpr *E);
203
204  Value *VisitCallExpr(const CallExpr *E) {
205    if (E->getCallReturnType()->isReferenceType())
206      return EmitLoadOfLValue(E);
207
208    return CGF.EmitCallExpr(E).getScalarVal();
209  }
210
211  Value *VisitStmtExpr(const StmtExpr *E);
212
213  Value *VisitBlockDeclRefExpr(const BlockDeclRefExpr *E);
214
215  // Unary Operators.
216  Value *VisitUnaryPostDec(const UnaryOperator *E) {
217    LValue LV = EmitLValue(E->getSubExpr());
218    return EmitScalarPrePostIncDec(E, LV, false, false);
219  }
220  Value *VisitUnaryPostInc(const UnaryOperator *E) {
221    LValue LV = EmitLValue(E->getSubExpr());
222    return EmitScalarPrePostIncDec(E, LV, true, false);
223  }
224  Value *VisitUnaryPreDec(const UnaryOperator *E) {
225    LValue LV = EmitLValue(E->getSubExpr());
226    return EmitScalarPrePostIncDec(E, LV, false, true);
227  }
228  Value *VisitUnaryPreInc(const UnaryOperator *E) {
229    LValue LV = EmitLValue(E->getSubExpr());
230    return EmitScalarPrePostIncDec(E, LV, true, true);
231  }
232
233  llvm::Value *EmitScalarPrePostIncDec(const UnaryOperator *E, LValue LV,
234                                       bool isInc, bool isPre);
235
236
237  Value *VisitUnaryAddrOf(const UnaryOperator *E) {
238    return EmitLValue(E->getSubExpr()).getAddress();
239  }
240  Value *VisitUnaryDeref(const Expr *E) { return EmitLoadOfLValue(E); }
241  Value *VisitUnaryPlus(const UnaryOperator *E) {
242    // This differs from gcc, though, most likely due to a bug in gcc.
243    TestAndClearIgnoreResultAssign();
244    return Visit(E->getSubExpr());
245  }
246  Value *VisitUnaryMinus    (const UnaryOperator *E);
247  Value *VisitUnaryNot      (const UnaryOperator *E);
248  Value *VisitUnaryLNot     (const UnaryOperator *E);
249  Value *VisitUnaryReal     (const UnaryOperator *E);
250  Value *VisitUnaryImag     (const UnaryOperator *E);
251  Value *VisitUnaryExtension(const UnaryOperator *E) {
252    return Visit(E->getSubExpr());
253  }
254  Value *VisitUnaryOffsetOf(const UnaryOperator *E);
255
256  // C++
257  Value *VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) {
258    return Visit(DAE->getExpr());
259  }
260  Value *VisitCXXThisExpr(CXXThisExpr *TE) {
261    return CGF.LoadCXXThis();
262  }
263
264  Value *VisitCXXExprWithTemporaries(CXXExprWithTemporaries *E) {
265    return CGF.EmitCXXExprWithTemporaries(E).getScalarVal();
266  }
267  Value *VisitCXXNewExpr(const CXXNewExpr *E) {
268    return CGF.EmitCXXNewExpr(E);
269  }
270  Value *VisitCXXDeleteExpr(const CXXDeleteExpr *E) {
271    CGF.EmitCXXDeleteExpr(E);
272    return 0;
273  }
274  Value *VisitUnaryTypeTraitExpr(const UnaryTypeTraitExpr *E) {
275    return llvm::ConstantInt::get(Builder.getInt1Ty(),
276                                  E->EvaluateTrait(CGF.getContext()));
277  }
278
279  Value *VisitCXXPseudoDestructorExpr(const CXXPseudoDestructorExpr *E) {
280    // C++ [expr.pseudo]p1:
281    //   The result shall only be used as the operand for the function call
282    //   operator (), and the result of such a call has type void. The only
283    //   effect is the evaluation of the postfix-expression before the dot or
284    //   arrow.
285    CGF.EmitScalarExpr(E->getBase());
286    return 0;
287  }
288
289  Value *VisitCXXNullPtrLiteralExpr(const CXXNullPtrLiteralExpr *E) {
290    return EmitNullValue(E->getType());
291  }
292
293  Value *VisitCXXThrowExpr(const CXXThrowExpr *E) {
294    CGF.EmitCXXThrowExpr(E);
295    return 0;
296  }
297
298  // Binary Operators.
299  Value *EmitMul(const BinOpInfo &Ops) {
300    if (Ops.Ty->isSignedIntegerType()) {
301      switch (CGF.getContext().getLangOptions().getSignedOverflowBehavior()) {
302      case LangOptions::SOB_Undefined:
303        return Builder.CreateNSWMul(Ops.LHS, Ops.RHS, "mul");
304      case LangOptions::SOB_Defined:
305        return Builder.CreateMul(Ops.LHS, Ops.RHS, "mul");
306      case LangOptions::SOB_Trapping:
307        return EmitOverflowCheckedBinOp(Ops);
308      }
309    }
310
311    if (Ops.LHS->getType()->isFPOrFPVectorTy())
312      return Builder.CreateFMul(Ops.LHS, Ops.RHS, "mul");
313    return Builder.CreateMul(Ops.LHS, Ops.RHS, "mul");
314  }
315  /// Create a binary op that checks for overflow.
316  /// Currently only supports +, - and *.
317  Value *EmitOverflowCheckedBinOp(const BinOpInfo &Ops);
318  Value *EmitDiv(const BinOpInfo &Ops);
319  Value *EmitRem(const BinOpInfo &Ops);
320  Value *EmitAdd(const BinOpInfo &Ops);
321  Value *EmitSub(const BinOpInfo &Ops);
322  Value *EmitShl(const BinOpInfo &Ops);
323  Value *EmitShr(const BinOpInfo &Ops);
324  Value *EmitAnd(const BinOpInfo &Ops) {
325    return Builder.CreateAnd(Ops.LHS, Ops.RHS, "and");
326  }
327  Value *EmitXor(const BinOpInfo &Ops) {
328    return Builder.CreateXor(Ops.LHS, Ops.RHS, "xor");
329  }
330  Value *EmitOr (const BinOpInfo &Ops) {
331    return Builder.CreateOr(Ops.LHS, Ops.RHS, "or");
332  }
333
334  BinOpInfo EmitBinOps(const BinaryOperator *E);
335  LValue EmitCompoundAssignLValue(const CompoundAssignOperator *E,
336                            Value *(ScalarExprEmitter::*F)(const BinOpInfo &),
337                                  Value *&BitFieldResult);
338
339  Value *EmitCompoundAssign(const CompoundAssignOperator *E,
340                            Value *(ScalarExprEmitter::*F)(const BinOpInfo &));
341
342  // Binary operators and binary compound assignment operators.
343#define HANDLEBINOP(OP) \
344  Value *VisitBin ## OP(const BinaryOperator *E) {                         \
345    return Emit ## OP(EmitBinOps(E));                                      \
346  }                                                                        \
347  Value *VisitBin ## OP ## Assign(const CompoundAssignOperator *E) {       \
348    return EmitCompoundAssign(E, &ScalarExprEmitter::Emit ## OP);          \
349  }
350  HANDLEBINOP(Mul)
351  HANDLEBINOP(Div)
352  HANDLEBINOP(Rem)
353  HANDLEBINOP(Add)
354  HANDLEBINOP(Sub)
355  HANDLEBINOP(Shl)
356  HANDLEBINOP(Shr)
357  HANDLEBINOP(And)
358  HANDLEBINOP(Xor)
359  HANDLEBINOP(Or)
360#undef HANDLEBINOP
361
362  // Comparisons.
363  Value *EmitCompare(const BinaryOperator *E, unsigned UICmpOpc,
364                     unsigned SICmpOpc, unsigned FCmpOpc);
365#define VISITCOMP(CODE, UI, SI, FP) \
366    Value *VisitBin##CODE(const BinaryOperator *E) { \
367      return EmitCompare(E, llvm::ICmpInst::UI, llvm::ICmpInst::SI, \
368                         llvm::FCmpInst::FP); }
369  VISITCOMP(LT, ICMP_ULT, ICMP_SLT, FCMP_OLT)
370  VISITCOMP(GT, ICMP_UGT, ICMP_SGT, FCMP_OGT)
371  VISITCOMP(LE, ICMP_ULE, ICMP_SLE, FCMP_OLE)
372  VISITCOMP(GE, ICMP_UGE, ICMP_SGE, FCMP_OGE)
373  VISITCOMP(EQ, ICMP_EQ , ICMP_EQ , FCMP_OEQ)
374  VISITCOMP(NE, ICMP_NE , ICMP_NE , FCMP_UNE)
375#undef VISITCOMP
376
377  Value *VisitBinAssign     (const BinaryOperator *E);
378
379  Value *VisitBinLAnd       (const BinaryOperator *E);
380  Value *VisitBinLOr        (const BinaryOperator *E);
381  Value *VisitBinComma      (const BinaryOperator *E);
382
383  Value *VisitBinPtrMemD(const Expr *E) { return EmitLoadOfLValue(E); }
384  Value *VisitBinPtrMemI(const Expr *E) { return EmitLoadOfLValue(E); }
385
386  // Other Operators.
387  Value *VisitBlockExpr(const BlockExpr *BE);
388  Value *VisitConditionalOperator(const ConditionalOperator *CO);
389  Value *VisitChooseExpr(ChooseExpr *CE);
390  Value *VisitVAArgExpr(VAArgExpr *VE);
391  Value *VisitObjCStringLiteral(const ObjCStringLiteral *E) {
392    return CGF.EmitObjCStringLiteral(E);
393  }
394};
395}  // end anonymous namespace.
396
397//===----------------------------------------------------------------------===//
398//                                Utilities
399//===----------------------------------------------------------------------===//
400
401/// EmitConversionToBool - Convert the specified expression value to a
402/// boolean (i1) truth value.  This is equivalent to "Val != 0".
403Value *ScalarExprEmitter::EmitConversionToBool(Value *Src, QualType SrcType) {
404  assert(SrcType.isCanonical() && "EmitScalarConversion strips typedefs");
405
406  if (SrcType->isRealFloatingType()) {
407    // Compare against 0.0 for fp scalars.
408    llvm::Value *Zero = llvm::Constant::getNullValue(Src->getType());
409    return Builder.CreateFCmpUNE(Src, Zero, "tobool");
410  }
411
412  if (SrcType->isMemberPointerType()) {
413    // Compare against -1.
414    llvm::Value *NegativeOne = llvm::Constant::getAllOnesValue(Src->getType());
415    return Builder.CreateICmpNE(Src, NegativeOne, "tobool");
416  }
417
418  assert((SrcType->isIntegerType() || isa<llvm::PointerType>(Src->getType())) &&
419         "Unknown scalar type to convert");
420
421  // Because of the type rules of C, we often end up computing a logical value,
422  // then zero extending it to int, then wanting it as a logical value again.
423  // Optimize this common case.
424  if (llvm::ZExtInst *ZI = dyn_cast<llvm::ZExtInst>(Src)) {
425    if (ZI->getOperand(0)->getType() ==
426        llvm::Type::getInt1Ty(CGF.getLLVMContext())) {
427      Value *Result = ZI->getOperand(0);
428      // If there aren't any more uses, zap the instruction to save space.
429      // Note that there can be more uses, for example if this
430      // is the result of an assignment.
431      if (ZI->use_empty())
432        ZI->eraseFromParent();
433      return Result;
434    }
435  }
436
437  // Compare against an integer or pointer null.
438  llvm::Value *Zero = llvm::Constant::getNullValue(Src->getType());
439  return Builder.CreateICmpNE(Src, Zero, "tobool");
440}
441
442/// EmitScalarConversion - Emit a conversion from the specified type to the
443/// specified destination type, both of which are LLVM scalar types.
444Value *ScalarExprEmitter::EmitScalarConversion(Value *Src, QualType SrcType,
445                                               QualType DstType) {
446  SrcType = CGF.getContext().getCanonicalType(SrcType);
447  DstType = CGF.getContext().getCanonicalType(DstType);
448  if (SrcType == DstType) return Src;
449
450  if (DstType->isVoidType()) return 0;
451
452  // Handle conversions to bool first, they are special: comparisons against 0.
453  if (DstType->isBooleanType())
454    return EmitConversionToBool(Src, SrcType);
455
456  const llvm::Type *DstTy = ConvertType(DstType);
457
458  // Ignore conversions like int -> uint.
459  if (Src->getType() == DstTy)
460    return Src;
461
462  // Handle pointer conversions next: pointers can only be converted to/from
463  // other pointers and integers. Check for pointer types in terms of LLVM, as
464  // some native types (like Obj-C id) may map to a pointer type.
465  if (isa<llvm::PointerType>(DstTy)) {
466    // The source value may be an integer, or a pointer.
467    if (isa<llvm::PointerType>(Src->getType()))
468      return Builder.CreateBitCast(Src, DstTy, "conv");
469
470    assert(SrcType->isIntegerType() && "Not ptr->ptr or int->ptr conversion?");
471    // First, convert to the correct width so that we control the kind of
472    // extension.
473    const llvm::Type *MiddleTy = CGF.IntPtrTy;
474    bool InputSigned = SrcType->isSignedIntegerType();
475    llvm::Value* IntResult =
476        Builder.CreateIntCast(Src, MiddleTy, InputSigned, "conv");
477    // Then, cast to pointer.
478    return Builder.CreateIntToPtr(IntResult, DstTy, "conv");
479  }
480
481  if (isa<llvm::PointerType>(Src->getType())) {
482    // Must be an ptr to int cast.
483    assert(isa<llvm::IntegerType>(DstTy) && "not ptr->int?");
484    return Builder.CreatePtrToInt(Src, DstTy, "conv");
485  }
486
487  // A scalar can be splatted to an extended vector of the same element type
488  if (DstType->isExtVectorType() && !SrcType->isVectorType()) {
489    // Cast the scalar to element type
490    QualType EltTy = DstType->getAs<ExtVectorType>()->getElementType();
491    llvm::Value *Elt = EmitScalarConversion(Src, SrcType, EltTy);
492
493    // Insert the element in element zero of an undef vector
494    llvm::Value *UnV = llvm::UndefValue::get(DstTy);
495    llvm::Value *Idx = llvm::ConstantInt::get(CGF.Int32Ty, 0);
496    UnV = Builder.CreateInsertElement(UnV, Elt, Idx, "tmp");
497
498    // Splat the element across to all elements
499    llvm::SmallVector<llvm::Constant*, 16> Args;
500    unsigned NumElements = cast<llvm::VectorType>(DstTy)->getNumElements();
501    for (unsigned i = 0; i < NumElements; i++)
502      Args.push_back(llvm::ConstantInt::get(CGF.Int32Ty, 0));
503
504    llvm::Constant *Mask = llvm::ConstantVector::get(&Args[0], NumElements);
505    llvm::Value *Yay = Builder.CreateShuffleVector(UnV, UnV, Mask, "splat");
506    return Yay;
507  }
508
509  // Allow bitcast from vector to integer/fp of the same size.
510  if (isa<llvm::VectorType>(Src->getType()) ||
511      isa<llvm::VectorType>(DstTy))
512    return Builder.CreateBitCast(Src, DstTy, "conv");
513
514  // Finally, we have the arithmetic types: real int/float.
515  if (isa<llvm::IntegerType>(Src->getType())) {
516    bool InputSigned = SrcType->isSignedIntegerType();
517    if (isa<llvm::IntegerType>(DstTy))
518      return Builder.CreateIntCast(Src, DstTy, InputSigned, "conv");
519    else if (InputSigned)
520      return Builder.CreateSIToFP(Src, DstTy, "conv");
521    else
522      return Builder.CreateUIToFP(Src, DstTy, "conv");
523  }
524
525  assert(Src->getType()->isFloatingPointTy() && "Unknown real conversion");
526  if (isa<llvm::IntegerType>(DstTy)) {
527    if (DstType->isSignedIntegerType())
528      return Builder.CreateFPToSI(Src, DstTy, "conv");
529    else
530      return Builder.CreateFPToUI(Src, DstTy, "conv");
531  }
532
533  assert(DstTy->isFloatingPointTy() && "Unknown real conversion");
534  if (DstTy->getTypeID() < Src->getType()->getTypeID())
535    return Builder.CreateFPTrunc(Src, DstTy, "conv");
536  else
537    return Builder.CreateFPExt(Src, DstTy, "conv");
538}
539
540/// EmitComplexToScalarConversion - Emit a conversion from the specified complex
541/// type to the specified destination type, where the destination type is an
542/// LLVM scalar type.
543Value *ScalarExprEmitter::
544EmitComplexToScalarConversion(CodeGenFunction::ComplexPairTy Src,
545                              QualType SrcTy, QualType DstTy) {
546  // Get the source element type.
547  SrcTy = SrcTy->getAs<ComplexType>()->getElementType();
548
549  // Handle conversions to bool first, they are special: comparisons against 0.
550  if (DstTy->isBooleanType()) {
551    //  Complex != 0  -> (Real != 0) | (Imag != 0)
552    Src.first  = EmitScalarConversion(Src.first, SrcTy, DstTy);
553    Src.second = EmitScalarConversion(Src.second, SrcTy, DstTy);
554    return Builder.CreateOr(Src.first, Src.second, "tobool");
555  }
556
557  // C99 6.3.1.7p2: "When a value of complex type is converted to a real type,
558  // the imaginary part of the complex value is discarded and the value of the
559  // real part is converted according to the conversion rules for the
560  // corresponding real type.
561  return EmitScalarConversion(Src.first, SrcTy, DstTy);
562}
563
564Value *ScalarExprEmitter::EmitNullValue(QualType Ty) {
565  const llvm::Type *LTy = ConvertType(Ty);
566
567  if (!Ty->isMemberPointerType())
568    return llvm::Constant::getNullValue(LTy);
569
570  assert(!Ty->isMemberFunctionPointerType() &&
571         "member function pointers are not scalar!");
572
573  // Itanium C++ ABI 2.3:
574  //   A NULL pointer is represented as -1.
575  return llvm::ConstantInt::get(LTy, -1ULL, /*isSigned=*/true);
576}
577
578//===----------------------------------------------------------------------===//
579//                            Visitor Methods
580//===----------------------------------------------------------------------===//
581
582Value *ScalarExprEmitter::VisitExpr(Expr *E) {
583  CGF.ErrorUnsupported(E, "scalar expression");
584  if (E->getType()->isVoidType())
585    return 0;
586  return llvm::UndefValue::get(CGF.ConvertType(E->getType()));
587}
588
589Value *ScalarExprEmitter::VisitShuffleVectorExpr(ShuffleVectorExpr *E) {
590  // Vector Mask Case
591  if (E->getNumSubExprs() == 2 ||
592      (E->getNumSubExprs() == 3 && E->getExpr(2)->getType()->isVectorType())) {
593    Value *LHS = CGF.EmitScalarExpr(E->getExpr(0));
594    Value *RHS = CGF.EmitScalarExpr(E->getExpr(1));
595    Value *Mask;
596
597    const llvm::VectorType *LTy = cast<llvm::VectorType>(LHS->getType());
598    unsigned LHSElts = LTy->getNumElements();
599
600    if (E->getNumSubExprs() == 3) {
601      Mask = CGF.EmitScalarExpr(E->getExpr(2));
602
603      // Shuffle LHS & RHS into one input vector.
604      llvm::SmallVector<llvm::Constant*, 32> concat;
605      for (unsigned i = 0; i != LHSElts; ++i) {
606        concat.push_back(llvm::ConstantInt::get(CGF.Int32Ty, 2*i));
607        concat.push_back(llvm::ConstantInt::get(CGF.Int32Ty, 2*i+1));
608      }
609
610      Value* CV = llvm::ConstantVector::get(concat.begin(), concat.size());
611      LHS = Builder.CreateShuffleVector(LHS, RHS, CV, "concat");
612      LHSElts *= 2;
613    } else {
614      Mask = RHS;
615    }
616
617    const llvm::VectorType *MTy = cast<llvm::VectorType>(Mask->getType());
618    llvm::Constant* EltMask;
619
620    // Treat vec3 like vec4.
621    if ((LHSElts == 6) && (E->getNumSubExprs() == 3))
622      EltMask = llvm::ConstantInt::get(MTy->getElementType(),
623                                       (1 << llvm::Log2_32(LHSElts+2))-1);
624    else if ((LHSElts == 3) && (E->getNumSubExprs() == 2))
625      EltMask = llvm::ConstantInt::get(MTy->getElementType(),
626                                       (1 << llvm::Log2_32(LHSElts+1))-1);
627    else
628      EltMask = llvm::ConstantInt::get(MTy->getElementType(),
629                                       (1 << llvm::Log2_32(LHSElts))-1);
630
631    // Mask off the high bits of each shuffle index.
632    llvm::SmallVector<llvm::Constant *, 32> MaskV;
633    for (unsigned i = 0, e = MTy->getNumElements(); i != e; ++i)
634      MaskV.push_back(EltMask);
635
636    Value* MaskBits = llvm::ConstantVector::get(MaskV.begin(), MaskV.size());
637    Mask = Builder.CreateAnd(Mask, MaskBits, "mask");
638
639    // newv = undef
640    // mask = mask & maskbits
641    // for each elt
642    //   n = extract mask i
643    //   x = extract val n
644    //   newv = insert newv, x, i
645    const llvm::VectorType *RTy = llvm::VectorType::get(LTy->getElementType(),
646                                                        MTy->getNumElements());
647    Value* NewV = llvm::UndefValue::get(RTy);
648    for (unsigned i = 0, e = MTy->getNumElements(); i != e; ++i) {
649      Value *Indx = llvm::ConstantInt::get(CGF.Int32Ty, i);
650      Indx = Builder.CreateExtractElement(Mask, Indx, "shuf_idx");
651      Indx = Builder.CreateZExt(Indx, CGF.Int32Ty, "idx_zext");
652
653      // Handle vec3 special since the index will be off by one for the RHS.
654      if ((LHSElts == 6) && (E->getNumSubExprs() == 3)) {
655        Value *cmpIndx, *newIndx;
656        cmpIndx = Builder.CreateICmpUGT(Indx,
657                                        llvm::ConstantInt::get(CGF.Int32Ty, 3),
658                                        "cmp_shuf_idx");
659        newIndx = Builder.CreateSub(Indx, llvm::ConstantInt::get(CGF.Int32Ty,1),
660                                    "shuf_idx_adj");
661        Indx = Builder.CreateSelect(cmpIndx, newIndx, Indx, "sel_shuf_idx");
662      }
663      Value *VExt = Builder.CreateExtractElement(LHS, Indx, "shuf_elt");
664      NewV = Builder.CreateInsertElement(NewV, VExt, Indx, "shuf_ins");
665    }
666    return NewV;
667  }
668
669  Value* V1 = CGF.EmitScalarExpr(E->getExpr(0));
670  Value* V2 = CGF.EmitScalarExpr(E->getExpr(1));
671
672  // Handle vec3 special since the index will be off by one for the RHS.
673  llvm::SmallVector<llvm::Constant*, 32> indices;
674  for (unsigned i = 2; i < E->getNumSubExprs(); i++) {
675    llvm::Constant *C = cast<llvm::Constant>(CGF.EmitScalarExpr(E->getExpr(i)));
676    const llvm::VectorType *VTy = cast<llvm::VectorType>(V1->getType());
677    if (VTy->getNumElements() == 3) {
678      if (llvm::ConstantInt *CI = dyn_cast<llvm::ConstantInt>(C)) {
679        uint64_t cVal = CI->getZExtValue();
680        if (cVal > 3) {
681          C = llvm::ConstantInt::get(C->getType(), cVal-1);
682        }
683      }
684    }
685    indices.push_back(C);
686  }
687
688  Value* SV = llvm::ConstantVector::get(indices.begin(), indices.size());
689  return Builder.CreateShuffleVector(V1, V2, SV, "shuffle");
690}
691Value *ScalarExprEmitter::VisitMemberExpr(MemberExpr *E) {
692  Expr::EvalResult Result;
693  if (E->Evaluate(Result, CGF.getContext()) && Result.Val.isInt()) {
694    if (E->isArrow())
695      CGF.EmitScalarExpr(E->getBase());
696    else
697      EmitLValue(E->getBase());
698    return llvm::ConstantInt::get(VMContext, Result.Val.getInt());
699  }
700  return EmitLoadOfLValue(E);
701}
702
703Value *ScalarExprEmitter::VisitArraySubscriptExpr(ArraySubscriptExpr *E) {
704  TestAndClearIgnoreResultAssign();
705
706  // Emit subscript expressions in rvalue context's.  For most cases, this just
707  // loads the lvalue formed by the subscript expr.  However, we have to be
708  // careful, because the base of a vector subscript is occasionally an rvalue,
709  // so we can't get it as an lvalue.
710  if (!E->getBase()->getType()->isVectorType())
711    return EmitLoadOfLValue(E);
712
713  // Handle the vector case.  The base must be a vector, the index must be an
714  // integer value.
715  Value *Base = Visit(E->getBase());
716  Value *Idx  = Visit(E->getIdx());
717  bool IdxSigned = E->getIdx()->getType()->isSignedIntegerType();
718  Idx = Builder.CreateIntCast(Idx, CGF.Int32Ty, IdxSigned, "vecidxcast");
719  return Builder.CreateExtractElement(Base, Idx, "vecext");
720}
721
722static llvm::Constant *getMaskElt(llvm::ShuffleVectorInst *SVI, unsigned Idx,
723                                  unsigned Off, const llvm::Type *I32Ty) {
724  int MV = SVI->getMaskValue(Idx);
725  if (MV == -1)
726    return llvm::UndefValue::get(I32Ty);
727  return llvm::ConstantInt::get(I32Ty, Off+MV);
728}
729
730Value *ScalarExprEmitter::VisitInitListExpr(InitListExpr *E) {
731  bool Ignore = TestAndClearIgnoreResultAssign();
732  (void)Ignore;
733  assert (Ignore == false && "init list ignored");
734  unsigned NumInitElements = E->getNumInits();
735
736  if (E->hadArrayRangeDesignator())
737    CGF.ErrorUnsupported(E, "GNU array range designator extension");
738
739  const llvm::VectorType *VType =
740    dyn_cast<llvm::VectorType>(ConvertType(E->getType()));
741
742  // We have a scalar in braces. Just use the first element.
743  if (!VType)
744    return Visit(E->getInit(0));
745
746  unsigned ResElts = VType->getNumElements();
747
748  // Loop over initializers collecting the Value for each, and remembering
749  // whether the source was swizzle (ExtVectorElementExpr).  This will allow
750  // us to fold the shuffle for the swizzle into the shuffle for the vector
751  // initializer, since LLVM optimizers generally do not want to touch
752  // shuffles.
753  unsigned CurIdx = 0;
754  bool VIsUndefShuffle = false;
755  llvm::Value *V = llvm::UndefValue::get(VType);
756  for (unsigned i = 0; i != NumInitElements; ++i) {
757    Expr *IE = E->getInit(i);
758    Value *Init = Visit(IE);
759    llvm::SmallVector<llvm::Constant*, 16> Args;
760
761    const llvm::VectorType *VVT = dyn_cast<llvm::VectorType>(Init->getType());
762
763    // Handle scalar elements.  If the scalar initializer is actually one
764    // element of a different vector of the same width, use shuffle instead of
765    // extract+insert.
766    if (!VVT) {
767      if (isa<ExtVectorElementExpr>(IE)) {
768        llvm::ExtractElementInst *EI = cast<llvm::ExtractElementInst>(Init);
769
770        if (EI->getVectorOperandType()->getNumElements() == ResElts) {
771          llvm::ConstantInt *C = cast<llvm::ConstantInt>(EI->getIndexOperand());
772          Value *LHS = 0, *RHS = 0;
773          if (CurIdx == 0) {
774            // insert into undef -> shuffle (src, undef)
775            Args.push_back(C);
776            for (unsigned j = 1; j != ResElts; ++j)
777              Args.push_back(llvm::UndefValue::get(CGF.Int32Ty));
778
779            LHS = EI->getVectorOperand();
780            RHS = V;
781            VIsUndefShuffle = true;
782          } else if (VIsUndefShuffle) {
783            // insert into undefshuffle && size match -> shuffle (v, src)
784            llvm::ShuffleVectorInst *SVV = cast<llvm::ShuffleVectorInst>(V);
785            for (unsigned j = 0; j != CurIdx; ++j)
786              Args.push_back(getMaskElt(SVV, j, 0, CGF.Int32Ty));
787            Args.push_back(llvm::ConstantInt::get(CGF.Int32Ty,
788                                                  ResElts + C->getZExtValue()));
789            for (unsigned j = CurIdx + 1; j != ResElts; ++j)
790              Args.push_back(llvm::UndefValue::get(CGF.Int32Ty));
791
792            LHS = cast<llvm::ShuffleVectorInst>(V)->getOperand(0);
793            RHS = EI->getVectorOperand();
794            VIsUndefShuffle = false;
795          }
796          if (!Args.empty()) {
797            llvm::Constant *Mask = llvm::ConstantVector::get(&Args[0], ResElts);
798            V = Builder.CreateShuffleVector(LHS, RHS, Mask);
799            ++CurIdx;
800            continue;
801          }
802        }
803      }
804      Value *Idx = llvm::ConstantInt::get(CGF.Int32Ty, CurIdx);
805      V = Builder.CreateInsertElement(V, Init, Idx, "vecinit");
806      VIsUndefShuffle = false;
807      ++CurIdx;
808      continue;
809    }
810
811    unsigned InitElts = VVT->getNumElements();
812
813    // If the initializer is an ExtVecEltExpr (a swizzle), and the swizzle's
814    // input is the same width as the vector being constructed, generate an
815    // optimized shuffle of the swizzle input into the result.
816    unsigned Offset = (CurIdx == 0) ? 0 : ResElts;
817    if (isa<ExtVectorElementExpr>(IE)) {
818      llvm::ShuffleVectorInst *SVI = cast<llvm::ShuffleVectorInst>(Init);
819      Value *SVOp = SVI->getOperand(0);
820      const llvm::VectorType *OpTy = cast<llvm::VectorType>(SVOp->getType());
821
822      if (OpTy->getNumElements() == ResElts) {
823        for (unsigned j = 0; j != CurIdx; ++j) {
824          // If the current vector initializer is a shuffle with undef, merge
825          // this shuffle directly into it.
826          if (VIsUndefShuffle) {
827            Args.push_back(getMaskElt(cast<llvm::ShuffleVectorInst>(V), j, 0,
828                                      CGF.Int32Ty));
829          } else {
830            Args.push_back(llvm::ConstantInt::get(CGF.Int32Ty, j));
831          }
832        }
833        for (unsigned j = 0, je = InitElts; j != je; ++j)
834          Args.push_back(getMaskElt(SVI, j, Offset, CGF.Int32Ty));
835        for (unsigned j = CurIdx + InitElts; j != ResElts; ++j)
836          Args.push_back(llvm::UndefValue::get(CGF.Int32Ty));
837
838        if (VIsUndefShuffle)
839          V = cast<llvm::ShuffleVectorInst>(V)->getOperand(0);
840
841        Init = SVOp;
842      }
843    }
844
845    // Extend init to result vector length, and then shuffle its contribution
846    // to the vector initializer into V.
847    if (Args.empty()) {
848      for (unsigned j = 0; j != InitElts; ++j)
849        Args.push_back(llvm::ConstantInt::get(CGF.Int32Ty, j));
850      for (unsigned j = InitElts; j != ResElts; ++j)
851        Args.push_back(llvm::UndefValue::get(CGF.Int32Ty));
852      llvm::Constant *Mask = llvm::ConstantVector::get(&Args[0], ResElts);
853      Init = Builder.CreateShuffleVector(Init, llvm::UndefValue::get(VVT),
854                                         Mask, "vext");
855
856      Args.clear();
857      for (unsigned j = 0; j != CurIdx; ++j)
858        Args.push_back(llvm::ConstantInt::get(CGF.Int32Ty, j));
859      for (unsigned j = 0; j != InitElts; ++j)
860        Args.push_back(llvm::ConstantInt::get(CGF.Int32Ty, j+Offset));
861      for (unsigned j = CurIdx + InitElts; j != ResElts; ++j)
862        Args.push_back(llvm::UndefValue::get(CGF.Int32Ty));
863    }
864
865    // If V is undef, make sure it ends up on the RHS of the shuffle to aid
866    // merging subsequent shuffles into this one.
867    if (CurIdx == 0)
868      std::swap(V, Init);
869    llvm::Constant *Mask = llvm::ConstantVector::get(&Args[0], ResElts);
870    V = Builder.CreateShuffleVector(V, Init, Mask, "vecinit");
871    VIsUndefShuffle = isa<llvm::UndefValue>(Init);
872    CurIdx += InitElts;
873  }
874
875  // FIXME: evaluate codegen vs. shuffling against constant null vector.
876  // Emit remaining default initializers.
877  const llvm::Type *EltTy = VType->getElementType();
878
879  // Emit remaining default initializers
880  for (/* Do not initialize i*/; CurIdx < ResElts; ++CurIdx) {
881    Value *Idx = llvm::ConstantInt::get(CGF.Int32Ty, CurIdx);
882    llvm::Value *Init = llvm::Constant::getNullValue(EltTy);
883    V = Builder.CreateInsertElement(V, Init, Idx, "vecinit");
884  }
885  return V;
886}
887
888static bool ShouldNullCheckClassCastValue(const CastExpr *CE) {
889  const Expr *E = CE->getSubExpr();
890
891  if (CE->getCastKind() == CastExpr::CK_UncheckedDerivedToBase)
892    return false;
893
894  if (isa<CXXThisExpr>(E)) {
895    // We always assume that 'this' is never null.
896    return false;
897  }
898
899  if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(CE)) {
900    // And that lvalue casts are never null.
901    if (ICE->isLvalueCast())
902      return false;
903  }
904
905  return true;
906}
907
908// VisitCastExpr - Emit code for an explicit or implicit cast.  Implicit casts
909// have to handle a more broad range of conversions than explicit casts, as they
910// handle things like function to ptr-to-function decay etc.
911Value *ScalarExprEmitter::EmitCastExpr(CastExpr *CE) {
912  Expr *E = CE->getSubExpr();
913  QualType DestTy = CE->getType();
914  CastExpr::CastKind Kind = CE->getCastKind();
915
916  if (!DestTy->isVoidType())
917    TestAndClearIgnoreResultAssign();
918
919  // Since almost all cast kinds apply to scalars, this switch doesn't have
920  // a default case, so the compiler will warn on a missing case.  The cases
921  // are in the same order as in the CastKind enum.
922  switch (Kind) {
923  case CastExpr::CK_Unknown:
924    // FIXME: All casts should have a known kind!
925    //assert(0 && "Unknown cast kind!");
926    break;
927
928  case CastExpr::CK_AnyPointerToObjCPointerCast:
929  case CastExpr::CK_AnyPointerToBlockPointerCast:
930  case CastExpr::CK_BitCast: {
931    Value *Src = Visit(const_cast<Expr*>(E));
932    return Builder.CreateBitCast(Src, ConvertType(DestTy));
933  }
934  case CastExpr::CK_NoOp:
935  case CastExpr::CK_UserDefinedConversion:
936    return Visit(const_cast<Expr*>(E));
937
938  case CastExpr::CK_BaseToDerived: {
939    const CXXRecordDecl *DerivedClassDecl =
940      DestTy->getCXXRecordDeclForPointerType();
941
942    return CGF.GetAddressOfDerivedClass(Visit(E), DerivedClassDecl,
943                                        CE->getBasePath(),
944                                        ShouldNullCheckClassCastValue(CE));
945  }
946  case CastExpr::CK_UncheckedDerivedToBase:
947  case CastExpr::CK_DerivedToBase: {
948    const RecordType *DerivedClassTy =
949      E->getType()->getAs<PointerType>()->getPointeeType()->getAs<RecordType>();
950    CXXRecordDecl *DerivedClassDecl =
951      cast<CXXRecordDecl>(DerivedClassTy->getDecl());
952
953    return CGF.GetAddressOfBaseClass(Visit(E), DerivedClassDecl,
954                                     CE->getBasePath(),
955                                     ShouldNullCheckClassCastValue(CE));
956  }
957  case CastExpr::CK_Dynamic: {
958    Value *V = Visit(const_cast<Expr*>(E));
959    const CXXDynamicCastExpr *DCE = cast<CXXDynamicCastExpr>(CE);
960    return CGF.EmitDynamicCast(V, DCE);
961  }
962  case CastExpr::CK_ToUnion:
963    assert(0 && "Should be unreachable!");
964    break;
965
966  case CastExpr::CK_ArrayToPointerDecay: {
967    assert(E->getType()->isArrayType() &&
968           "Array to pointer decay must have array source type!");
969
970    Value *V = EmitLValue(E).getAddress();  // Bitfields can't be arrays.
971
972    // Note that VLA pointers are always decayed, so we don't need to do
973    // anything here.
974    if (!E->getType()->isVariableArrayType()) {
975      assert(isa<llvm::PointerType>(V->getType()) && "Expected pointer");
976      assert(isa<llvm::ArrayType>(cast<llvm::PointerType>(V->getType())
977                                 ->getElementType()) &&
978             "Expected pointer to array");
979      V = Builder.CreateStructGEP(V, 0, "arraydecay");
980    }
981
982    return V;
983  }
984  case CastExpr::CK_FunctionToPointerDecay:
985    return EmitLValue(E).getAddress();
986
987  case CastExpr::CK_NullToMemberPointer:
988    return CGF.CGM.EmitNullConstant(DestTy);
989
990  case CastExpr::CK_BaseToDerivedMemberPointer:
991  case CastExpr::CK_DerivedToBaseMemberPointer: {
992    Value *Src = Visit(E);
993
994    // See if we need to adjust the pointer.
995    const CXXRecordDecl *BaseDecl =
996      cast<CXXRecordDecl>(E->getType()->getAs<MemberPointerType>()->
997                          getClass()->getAs<RecordType>()->getDecl());
998    const CXXRecordDecl *DerivedDecl =
999      cast<CXXRecordDecl>(CE->getType()->getAs<MemberPointerType>()->
1000                          getClass()->getAs<RecordType>()->getDecl());
1001    if (CE->getCastKind() == CastExpr::CK_DerivedToBaseMemberPointer)
1002      std::swap(DerivedDecl, BaseDecl);
1003
1004    if (llvm::Constant *Adj =
1005          CGF.CGM.GetNonVirtualBaseClassOffset(DerivedDecl, CE->getBasePath())){
1006      if (CE->getCastKind() == CastExpr::CK_DerivedToBaseMemberPointer)
1007        Src = Builder.CreateNSWSub(Src, Adj, "adj");
1008      else
1009        Src = Builder.CreateNSWAdd(Src, Adj, "adj");
1010    }
1011
1012    return Src;
1013  }
1014
1015  case CastExpr::CK_ConstructorConversion:
1016    assert(0 && "Should be unreachable!");
1017    break;
1018
1019  case CastExpr::CK_IntegralToPointer: {
1020    Value *Src = Visit(const_cast<Expr*>(E));
1021
1022    // First, convert to the correct width so that we control the kind of
1023    // extension.
1024    const llvm::Type *MiddleTy = CGF.IntPtrTy;
1025    bool InputSigned = E->getType()->isSignedIntegerType();
1026    llvm::Value* IntResult =
1027      Builder.CreateIntCast(Src, MiddleTy, InputSigned, "conv");
1028
1029    return Builder.CreateIntToPtr(IntResult, ConvertType(DestTy));
1030  }
1031  case CastExpr::CK_PointerToIntegral: {
1032    Value *Src = Visit(const_cast<Expr*>(E));
1033    return Builder.CreatePtrToInt(Src, ConvertType(DestTy));
1034  }
1035  case CastExpr::CK_ToVoid: {
1036    CGF.EmitAnyExpr(E, 0, false, true);
1037    return 0;
1038  }
1039  case CastExpr::CK_VectorSplat: {
1040    const llvm::Type *DstTy = ConvertType(DestTy);
1041    Value *Elt = Visit(const_cast<Expr*>(E));
1042
1043    // Insert the element in element zero of an undef vector
1044    llvm::Value *UnV = llvm::UndefValue::get(DstTy);
1045    llvm::Value *Idx = llvm::ConstantInt::get(CGF.Int32Ty, 0);
1046    UnV = Builder.CreateInsertElement(UnV, Elt, Idx, "tmp");
1047
1048    // Splat the element across to all elements
1049    llvm::SmallVector<llvm::Constant*, 16> Args;
1050    unsigned NumElements = cast<llvm::VectorType>(DstTy)->getNumElements();
1051    for (unsigned i = 0; i < NumElements; i++)
1052      Args.push_back(llvm::ConstantInt::get(CGF.Int32Ty, 0));
1053
1054    llvm::Constant *Mask = llvm::ConstantVector::get(&Args[0], NumElements);
1055    llvm::Value *Yay = Builder.CreateShuffleVector(UnV, UnV, Mask, "splat");
1056    return Yay;
1057  }
1058  case CastExpr::CK_IntegralCast:
1059  case CastExpr::CK_IntegralToFloating:
1060  case CastExpr::CK_FloatingToIntegral:
1061  case CastExpr::CK_FloatingCast:
1062    return EmitScalarConversion(Visit(E), E->getType(), DestTy);
1063
1064  case CastExpr::CK_MemberPointerToBoolean:
1065    return CGF.EvaluateExprAsBool(E);
1066  }
1067
1068  // Handle cases where the source is an non-complex type.
1069
1070  if (!CGF.hasAggregateLLVMType(E->getType())) {
1071    Value *Src = Visit(const_cast<Expr*>(E));
1072
1073    // Use EmitScalarConversion to perform the conversion.
1074    return EmitScalarConversion(Src, E->getType(), DestTy);
1075  }
1076
1077  if (E->getType()->isAnyComplexType()) {
1078    // Handle cases where the source is a complex type.
1079    bool IgnoreImag = true;
1080    bool IgnoreImagAssign = true;
1081    bool IgnoreReal = IgnoreResultAssign;
1082    bool IgnoreRealAssign = IgnoreResultAssign;
1083    if (DestTy->isBooleanType())
1084      IgnoreImagAssign = IgnoreImag = false;
1085    else if (DestTy->isVoidType()) {
1086      IgnoreReal = IgnoreImag = false;
1087      IgnoreRealAssign = IgnoreImagAssign = true;
1088    }
1089    CodeGenFunction::ComplexPairTy V
1090      = CGF.EmitComplexExpr(E, IgnoreReal, IgnoreImag, IgnoreRealAssign,
1091                            IgnoreImagAssign);
1092    return EmitComplexToScalarConversion(V, E->getType(), DestTy);
1093  }
1094
1095  // Okay, this is a cast from an aggregate.  It must be a cast to void.  Just
1096  // evaluate the result and return.
1097  CGF.EmitAggExpr(E, 0, false, true);
1098  return 0;
1099}
1100
1101Value *ScalarExprEmitter::VisitStmtExpr(const StmtExpr *E) {
1102  return CGF.EmitCompoundStmt(*E->getSubStmt(),
1103                              !E->getType()->isVoidType()).getScalarVal();
1104}
1105
1106Value *ScalarExprEmitter::VisitBlockDeclRefExpr(const BlockDeclRefExpr *E) {
1107  llvm::Value *V = CGF.GetAddrOfBlockDecl(E);
1108  if (E->getType().isObjCGCWeak())
1109    return CGF.CGM.getObjCRuntime().EmitObjCWeakRead(CGF, V);
1110  return Builder.CreateLoad(V, "tmp");
1111}
1112
1113//===----------------------------------------------------------------------===//
1114//                             Unary Operators
1115//===----------------------------------------------------------------------===//
1116
1117llvm::Value *ScalarExprEmitter::
1118EmitScalarPrePostIncDec(const UnaryOperator *E, LValue LV,
1119                        bool isInc, bool isPre) {
1120
1121  QualType ValTy = E->getSubExpr()->getType();
1122  llvm::Value *InVal = EmitLoadOfLValue(LV, ValTy);
1123
1124  int AmountVal = isInc ? 1 : -1;
1125
1126  if (ValTy->isPointerType() &&
1127      ValTy->getAs<PointerType>()->isVariableArrayType()) {
1128    // The amount of the addition/subtraction needs to account for the VLA size
1129    CGF.ErrorUnsupported(E, "VLA pointer inc/dec");
1130  }
1131
1132  llvm::Value *NextVal;
1133  if (const llvm::PointerType *PT =
1134      dyn_cast<llvm::PointerType>(InVal->getType())) {
1135    llvm::Constant *Inc = llvm::ConstantInt::get(CGF.Int32Ty, AmountVal);
1136    if (!isa<llvm::FunctionType>(PT->getElementType())) {
1137      QualType PTEE = ValTy->getPointeeType();
1138      if (const ObjCObjectType *OIT = PTEE->getAs<ObjCObjectType>()) {
1139        // Handle interface types, which are not represented with a concrete
1140        // type.
1141        int size = CGF.getContext().getTypeSize(OIT) / 8;
1142        if (!isInc)
1143          size = -size;
1144        Inc = llvm::ConstantInt::get(Inc->getType(), size);
1145        const llvm::Type *i8Ty = llvm::Type::getInt8PtrTy(VMContext);
1146        InVal = Builder.CreateBitCast(InVal, i8Ty);
1147        NextVal = Builder.CreateGEP(InVal, Inc, "add.ptr");
1148        llvm::Value *lhs = LV.getAddress();
1149        lhs = Builder.CreateBitCast(lhs, llvm::PointerType::getUnqual(i8Ty));
1150        LV = LValue::MakeAddr(lhs, CGF.MakeQualifiers(ValTy));
1151      } else
1152        NextVal = Builder.CreateInBoundsGEP(InVal, Inc, "ptrincdec");
1153    } else {
1154      const llvm::Type *i8Ty = llvm::Type::getInt8PtrTy(VMContext);
1155      NextVal = Builder.CreateBitCast(InVal, i8Ty, "tmp");
1156      NextVal = Builder.CreateGEP(NextVal, Inc, "ptrincdec");
1157      NextVal = Builder.CreateBitCast(NextVal, InVal->getType());
1158    }
1159  } else if (InVal->getType()->isIntegerTy(1) && isInc) {
1160    // Bool++ is an interesting case, due to promotion rules, we get:
1161    // Bool++ -> Bool = Bool+1 -> Bool = (int)Bool+1 ->
1162    // Bool = ((int)Bool+1) != 0
1163    // An interesting aspect of this is that increment is always true.
1164    // Decrement does not have this property.
1165    NextVal = llvm::ConstantInt::getTrue(VMContext);
1166  } else if (isa<llvm::IntegerType>(InVal->getType())) {
1167    NextVal = llvm::ConstantInt::get(InVal->getType(), AmountVal);
1168
1169    if (!ValTy->isSignedIntegerType())
1170      // Unsigned integer inc is always two's complement.
1171      NextVal = Builder.CreateAdd(InVal, NextVal, isInc ? "inc" : "dec");
1172    else {
1173      switch (CGF.getContext().getLangOptions().getSignedOverflowBehavior()) {
1174      case LangOptions::SOB_Undefined:
1175        NextVal = Builder.CreateNSWAdd(InVal, NextVal, isInc ? "inc" : "dec");
1176        break;
1177      case LangOptions::SOB_Defined:
1178        NextVal = Builder.CreateAdd(InVal, NextVal, isInc ? "inc" : "dec");
1179        break;
1180      case LangOptions::SOB_Trapping:
1181        BinOpInfo BinOp;
1182        BinOp.LHS = InVal;
1183        BinOp.RHS = NextVal;
1184        BinOp.Ty = E->getType();
1185        BinOp.Opcode = BinaryOperator::Add;
1186        BinOp.E = E;
1187        return EmitOverflowCheckedBinOp(BinOp);
1188      }
1189    }
1190  } else {
1191    // Add the inc/dec to the real part.
1192    if (InVal->getType()->isFloatTy())
1193      NextVal =
1194      llvm::ConstantFP::get(VMContext,
1195                            llvm::APFloat(static_cast<float>(AmountVal)));
1196    else if (InVal->getType()->isDoubleTy())
1197      NextVal =
1198      llvm::ConstantFP::get(VMContext,
1199                            llvm::APFloat(static_cast<double>(AmountVal)));
1200    else {
1201      llvm::APFloat F(static_cast<float>(AmountVal));
1202      bool ignored;
1203      F.convert(CGF.Target.getLongDoubleFormat(), llvm::APFloat::rmTowardZero,
1204                &ignored);
1205      NextVal = llvm::ConstantFP::get(VMContext, F);
1206    }
1207    NextVal = Builder.CreateFAdd(InVal, NextVal, isInc ? "inc" : "dec");
1208  }
1209
1210  // Store the updated result through the lvalue.
1211  if (LV.isBitField())
1212    CGF.EmitStoreThroughBitfieldLValue(RValue::get(NextVal), LV, ValTy, &NextVal);
1213  else
1214    CGF.EmitStoreThroughLValue(RValue::get(NextVal), LV, ValTy);
1215
1216  // If this is a postinc, return the value read from memory, otherwise use the
1217  // updated value.
1218  return isPre ? NextVal : InVal;
1219}
1220
1221
1222
1223Value *ScalarExprEmitter::VisitUnaryMinus(const UnaryOperator *E) {
1224  TestAndClearIgnoreResultAssign();
1225  // Emit unary minus with EmitSub so we handle overflow cases etc.
1226  BinOpInfo BinOp;
1227  BinOp.RHS = Visit(E->getSubExpr());
1228
1229  if (BinOp.RHS->getType()->isFPOrFPVectorTy())
1230    BinOp.LHS = llvm::ConstantFP::getZeroValueForNegation(BinOp.RHS->getType());
1231  else
1232    BinOp.LHS = llvm::Constant::getNullValue(BinOp.RHS->getType());
1233  BinOp.Ty = E->getType();
1234  BinOp.Opcode = BinaryOperator::Sub;
1235  BinOp.E = E;
1236  return EmitSub(BinOp);
1237}
1238
1239Value *ScalarExprEmitter::VisitUnaryNot(const UnaryOperator *E) {
1240  TestAndClearIgnoreResultAssign();
1241  Value *Op = Visit(E->getSubExpr());
1242  return Builder.CreateNot(Op, "neg");
1243}
1244
1245Value *ScalarExprEmitter::VisitUnaryLNot(const UnaryOperator *E) {
1246  // Compare operand to zero.
1247  Value *BoolVal = CGF.EvaluateExprAsBool(E->getSubExpr());
1248
1249  // Invert value.
1250  // TODO: Could dynamically modify easy computations here.  For example, if
1251  // the operand is an icmp ne, turn into icmp eq.
1252  BoolVal = Builder.CreateNot(BoolVal, "lnot");
1253
1254  // ZExt result to the expr type.
1255  return Builder.CreateZExt(BoolVal, ConvertType(E->getType()), "lnot.ext");
1256}
1257
1258Value *ScalarExprEmitter::VisitOffsetOfExpr(const OffsetOfExpr *E) {
1259  Expr::EvalResult Result;
1260  if(E->Evaluate(Result, CGF.getContext()))
1261    return llvm::ConstantInt::get(VMContext, Result.Val.getInt());
1262
1263  // FIXME: Cannot support code generation for non-constant offsetof.
1264  unsigned DiagID = CGF.CGM.getDiags().getCustomDiagID(Diagnostic::Error,
1265                             "cannot compile non-constant __builtin_offsetof");
1266  CGF.CGM.getDiags().Report(CGF.getContext().getFullLoc(E->getLocStart()),
1267                            DiagID)
1268    << E->getSourceRange();
1269
1270  return llvm::Constant::getNullValue(ConvertType(E->getType()));
1271}
1272
1273/// VisitSizeOfAlignOfExpr - Return the size or alignment of the type of
1274/// argument of the sizeof expression as an integer.
1275Value *
1276ScalarExprEmitter::VisitSizeOfAlignOfExpr(const SizeOfAlignOfExpr *E) {
1277  QualType TypeToSize = E->getTypeOfArgument();
1278  if (E->isSizeOf()) {
1279    if (const VariableArrayType *VAT =
1280          CGF.getContext().getAsVariableArrayType(TypeToSize)) {
1281      if (E->isArgumentType()) {
1282        // sizeof(type) - make sure to emit the VLA size.
1283        CGF.EmitVLASize(TypeToSize);
1284      } else {
1285        // C99 6.5.3.4p2: If the argument is an expression of type
1286        // VLA, it is evaluated.
1287        CGF.EmitAnyExpr(E->getArgumentExpr());
1288      }
1289
1290      return CGF.GetVLASize(VAT);
1291    }
1292  }
1293
1294  // If this isn't sizeof(vla), the result must be constant; use the constant
1295  // folding logic so we don't have to duplicate it here.
1296  Expr::EvalResult Result;
1297  E->Evaluate(Result, CGF.getContext());
1298  return llvm::ConstantInt::get(VMContext, Result.Val.getInt());
1299}
1300
1301Value *ScalarExprEmitter::VisitUnaryReal(const UnaryOperator *E) {
1302  Expr *Op = E->getSubExpr();
1303  if (Op->getType()->isAnyComplexType())
1304    return CGF.EmitComplexExpr(Op, false, true, false, true).first;
1305  return Visit(Op);
1306}
1307Value *ScalarExprEmitter::VisitUnaryImag(const UnaryOperator *E) {
1308  Expr *Op = E->getSubExpr();
1309  if (Op->getType()->isAnyComplexType())
1310    return CGF.EmitComplexExpr(Op, true, false, true, false).second;
1311
1312  // __imag on a scalar returns zero.  Emit the subexpr to ensure side
1313  // effects are evaluated, but not the actual value.
1314  if (E->isLvalue(CGF.getContext()) == Expr::LV_Valid)
1315    CGF.EmitLValue(Op);
1316  else
1317    CGF.EmitScalarExpr(Op, true);
1318  return llvm::Constant::getNullValue(ConvertType(E->getType()));
1319}
1320
1321Value *ScalarExprEmitter::VisitUnaryOffsetOf(const UnaryOperator *E) {
1322  Value* ResultAsPtr = EmitLValue(E->getSubExpr()).getAddress();
1323  const llvm::Type* ResultType = ConvertType(E->getType());
1324  return Builder.CreatePtrToInt(ResultAsPtr, ResultType, "offsetof");
1325}
1326
1327//===----------------------------------------------------------------------===//
1328//                           Binary Operators
1329//===----------------------------------------------------------------------===//
1330
1331BinOpInfo ScalarExprEmitter::EmitBinOps(const BinaryOperator *E) {
1332  TestAndClearIgnoreResultAssign();
1333  BinOpInfo Result;
1334  Result.LHS = Visit(E->getLHS());
1335  Result.RHS = Visit(E->getRHS());
1336  Result.Ty  = E->getType();
1337  Result.Opcode = E->getOpcode();
1338  Result.E = E;
1339  return Result;
1340}
1341
1342LValue ScalarExprEmitter::EmitCompoundAssignLValue(
1343                                              const CompoundAssignOperator *E,
1344                        Value *(ScalarExprEmitter::*Func)(const BinOpInfo &),
1345                                                   Value *&BitFieldResult) {
1346  QualType LHSTy = E->getLHS()->getType();
1347  BitFieldResult = 0;
1348  BinOpInfo OpInfo;
1349
1350  if (E->getComputationResultType()->isAnyComplexType()) {
1351    // This needs to go through the complex expression emitter, but it's a tad
1352    // complicated to do that... I'm leaving it out for now.  (Note that we do
1353    // actually need the imaginary part of the RHS for multiplication and
1354    // division.)
1355    CGF.ErrorUnsupported(E, "complex compound assignment");
1356    llvm::UndefValue::get(CGF.ConvertType(E->getType()));
1357    return LValue();
1358  }
1359
1360  // Emit the RHS first.  __block variables need to have the rhs evaluated
1361  // first, plus this should improve codegen a little.
1362  OpInfo.RHS = Visit(E->getRHS());
1363  OpInfo.Ty = E->getComputationResultType();
1364  OpInfo.Opcode = E->getOpcode();
1365  OpInfo.E = E;
1366  // Load/convert the LHS.
1367  LValue LHSLV = EmitCheckedLValue(E->getLHS());
1368  OpInfo.LHS = EmitLoadOfLValue(LHSLV, LHSTy);
1369  OpInfo.LHS = EmitScalarConversion(OpInfo.LHS, LHSTy,
1370                                    E->getComputationLHSType());
1371
1372  // Expand the binary operator.
1373  Value *Result = (this->*Func)(OpInfo);
1374
1375  // Convert the result back to the LHS type.
1376  Result = EmitScalarConversion(Result, E->getComputationResultType(), LHSTy);
1377
1378  // Store the result value into the LHS lvalue. Bit-fields are handled
1379  // specially because the result is altered by the store, i.e., [C99 6.5.16p1]
1380  // 'An assignment expression has the value of the left operand after the
1381  // assignment...'.
1382  if (LHSLV.isBitField()) {
1383    if (!LHSLV.isVolatileQualified()) {
1384      CGF.EmitStoreThroughBitfieldLValue(RValue::get(Result), LHSLV, LHSTy,
1385                                         &Result);
1386      BitFieldResult = Result;
1387      return LHSLV;
1388    } else
1389      CGF.EmitStoreThroughBitfieldLValue(RValue::get(Result), LHSLV, LHSTy);
1390  } else
1391    CGF.EmitStoreThroughLValue(RValue::get(Result), LHSLV, LHSTy);
1392  return LHSLV;
1393}
1394
1395Value *ScalarExprEmitter::EmitCompoundAssign(const CompoundAssignOperator *E,
1396                      Value *(ScalarExprEmitter::*Func)(const BinOpInfo &)) {
1397  bool Ignore = TestAndClearIgnoreResultAssign();
1398  Value *BitFieldResult;
1399  LValue LHSLV = EmitCompoundAssignLValue(E, Func, BitFieldResult);
1400  if (BitFieldResult)
1401    return BitFieldResult;
1402
1403  if (Ignore)
1404    return 0;
1405  return EmitLoadOfLValue(LHSLV, E->getType());
1406}
1407
1408
1409Value *ScalarExprEmitter::EmitDiv(const BinOpInfo &Ops) {
1410  if (Ops.LHS->getType()->isFPOrFPVectorTy())
1411    return Builder.CreateFDiv(Ops.LHS, Ops.RHS, "div");
1412  else if (Ops.Ty->isUnsignedIntegerType())
1413    return Builder.CreateUDiv(Ops.LHS, Ops.RHS, "div");
1414  else
1415    return Builder.CreateSDiv(Ops.LHS, Ops.RHS, "div");
1416}
1417
1418Value *ScalarExprEmitter::EmitRem(const BinOpInfo &Ops) {
1419  // Rem in C can't be a floating point type: C99 6.5.5p2.
1420  if (Ops.Ty->isUnsignedIntegerType())
1421    return Builder.CreateURem(Ops.LHS, Ops.RHS, "rem");
1422  else
1423    return Builder.CreateSRem(Ops.LHS, Ops.RHS, "rem");
1424}
1425
1426Value *ScalarExprEmitter::EmitOverflowCheckedBinOp(const BinOpInfo &Ops) {
1427  unsigned IID;
1428  unsigned OpID = 0;
1429
1430  switch (Ops.Opcode) {
1431  case BinaryOperator::Add:
1432  case BinaryOperator::AddAssign:
1433    OpID = 1;
1434    IID = llvm::Intrinsic::sadd_with_overflow;
1435    break;
1436  case BinaryOperator::Sub:
1437  case BinaryOperator::SubAssign:
1438    OpID = 2;
1439    IID = llvm::Intrinsic::ssub_with_overflow;
1440    break;
1441  case BinaryOperator::Mul:
1442  case BinaryOperator::MulAssign:
1443    OpID = 3;
1444    IID = llvm::Intrinsic::smul_with_overflow;
1445    break;
1446  default:
1447    assert(false && "Unsupported operation for overflow detection");
1448    IID = 0;
1449  }
1450  OpID <<= 1;
1451  OpID |= 1;
1452
1453  const llvm::Type *opTy = CGF.CGM.getTypes().ConvertType(Ops.Ty);
1454
1455  llvm::Function *intrinsic = CGF.CGM.getIntrinsic(IID, &opTy, 1);
1456
1457  Value *resultAndOverflow = Builder.CreateCall2(intrinsic, Ops.LHS, Ops.RHS);
1458  Value *result = Builder.CreateExtractValue(resultAndOverflow, 0);
1459  Value *overflow = Builder.CreateExtractValue(resultAndOverflow, 1);
1460
1461  // Branch in case of overflow.
1462  llvm::BasicBlock *initialBB = Builder.GetInsertBlock();
1463  llvm::BasicBlock *overflowBB =
1464    CGF.createBasicBlock("overflow", CGF.CurFn);
1465  llvm::BasicBlock *continueBB =
1466    CGF.createBasicBlock("overflow.continue", CGF.CurFn);
1467
1468  Builder.CreateCondBr(overflow, overflowBB, continueBB);
1469
1470  // Handle overflow
1471
1472  Builder.SetInsertPoint(overflowBB);
1473
1474  // Handler is:
1475  // long long *__overflow_handler)(long long a, long long b, char op,
1476  // char width)
1477  std::vector<const llvm::Type*> handerArgTypes;
1478  handerArgTypes.push_back(CGF.Int64Ty);
1479  handerArgTypes.push_back(CGF.Int64Ty);
1480  handerArgTypes.push_back(llvm::Type::getInt8Ty(VMContext));
1481  handerArgTypes.push_back(llvm::Type::getInt8Ty(VMContext));
1482  llvm::FunctionType *handlerTy =
1483    llvm::FunctionType::get(CGF.Int64Ty, handerArgTypes, false);
1484  llvm::Value *handlerFunction =
1485    CGF.CGM.getModule().getOrInsertGlobal("__overflow_handler",
1486        llvm::PointerType::getUnqual(handlerTy));
1487  handlerFunction = Builder.CreateLoad(handlerFunction);
1488
1489  llvm::Value *handlerResult = Builder.CreateCall4(handlerFunction,
1490      Builder.CreateSExt(Ops.LHS, CGF.Int64Ty),
1491      Builder.CreateSExt(Ops.RHS, CGF.Int64Ty),
1492      llvm::ConstantInt::get(llvm::Type::getInt8Ty(VMContext), OpID),
1493      llvm::ConstantInt::get(llvm::Type::getInt8Ty(VMContext),
1494        cast<llvm::IntegerType>(opTy)->getBitWidth()));
1495
1496  handlerResult = Builder.CreateTrunc(handlerResult, opTy);
1497
1498  Builder.CreateBr(continueBB);
1499
1500  // Set up the continuation
1501  Builder.SetInsertPoint(continueBB);
1502  // Get the correct result
1503  llvm::PHINode *phi = Builder.CreatePHI(opTy);
1504  phi->reserveOperandSpace(2);
1505  phi->addIncoming(result, initialBB);
1506  phi->addIncoming(handlerResult, overflowBB);
1507
1508  return phi;
1509}
1510
1511Value *ScalarExprEmitter::EmitAdd(const BinOpInfo &Ops) {
1512  if (!Ops.Ty->isAnyPointerType()) {
1513    if (Ops.Ty->isSignedIntegerType()) {
1514      switch (CGF.getContext().getLangOptions().getSignedOverflowBehavior()) {
1515      case LangOptions::SOB_Undefined:
1516        return Builder.CreateNSWAdd(Ops.LHS, Ops.RHS, "add");
1517      case LangOptions::SOB_Defined:
1518        return Builder.CreateAdd(Ops.LHS, Ops.RHS, "add");
1519      case LangOptions::SOB_Trapping:
1520        return EmitOverflowCheckedBinOp(Ops);
1521      }
1522    }
1523
1524    if (Ops.LHS->getType()->isFPOrFPVectorTy())
1525      return Builder.CreateFAdd(Ops.LHS, Ops.RHS, "add");
1526
1527    return Builder.CreateAdd(Ops.LHS, Ops.RHS, "add");
1528  }
1529
1530  // Must have binary (not unary) expr here.  Unary pointer decrement doesn't
1531  // use this path.
1532  const BinaryOperator *BinOp = cast<BinaryOperator>(Ops.E);
1533
1534  if (Ops.Ty->isPointerType() &&
1535      Ops.Ty->getAs<PointerType>()->isVariableArrayType()) {
1536    // The amount of the addition needs to account for the VLA size
1537    CGF.ErrorUnsupported(BinOp, "VLA pointer addition");
1538  }
1539
1540  Value *Ptr, *Idx;
1541  Expr *IdxExp;
1542  const PointerType *PT = BinOp->getLHS()->getType()->getAs<PointerType>();
1543  const ObjCObjectPointerType *OPT =
1544    BinOp->getLHS()->getType()->getAs<ObjCObjectPointerType>();
1545  if (PT || OPT) {
1546    Ptr = Ops.LHS;
1547    Idx = Ops.RHS;
1548    IdxExp = BinOp->getRHS();
1549  } else {  // int + pointer
1550    PT = BinOp->getRHS()->getType()->getAs<PointerType>();
1551    OPT = BinOp->getRHS()->getType()->getAs<ObjCObjectPointerType>();
1552    assert((PT || OPT) && "Invalid add expr");
1553    Ptr = Ops.RHS;
1554    Idx = Ops.LHS;
1555    IdxExp = BinOp->getLHS();
1556  }
1557
1558  unsigned Width = cast<llvm::IntegerType>(Idx->getType())->getBitWidth();
1559  if (Width < CGF.LLVMPointerWidth) {
1560    // Zero or sign extend the pointer value based on whether the index is
1561    // signed or not.
1562    const llvm::Type *IdxType = CGF.IntPtrTy;
1563    if (IdxExp->getType()->isSignedIntegerType())
1564      Idx = Builder.CreateSExt(Idx, IdxType, "idx.ext");
1565    else
1566      Idx = Builder.CreateZExt(Idx, IdxType, "idx.ext");
1567  }
1568  const QualType ElementType = PT ? PT->getPointeeType() : OPT->getPointeeType();
1569  // Handle interface types, which are not represented with a concrete type.
1570  if (const ObjCObjectType *OIT = ElementType->getAs<ObjCObjectType>()) {
1571    llvm::Value *InterfaceSize =
1572      llvm::ConstantInt::get(Idx->getType(),
1573          CGF.getContext().getTypeSizeInChars(OIT).getQuantity());
1574    Idx = Builder.CreateMul(Idx, InterfaceSize);
1575    const llvm::Type *i8Ty = llvm::Type::getInt8PtrTy(VMContext);
1576    Value *Casted = Builder.CreateBitCast(Ptr, i8Ty);
1577    Value *Res = Builder.CreateGEP(Casted, Idx, "add.ptr");
1578    return Builder.CreateBitCast(Res, Ptr->getType());
1579  }
1580
1581  // Explicitly handle GNU void* and function pointer arithmetic extensions. The
1582  // GNU void* casts amount to no-ops since our void* type is i8*, but this is
1583  // future proof.
1584  if (ElementType->isVoidType() || ElementType->isFunctionType()) {
1585    const llvm::Type *i8Ty = llvm::Type::getInt8PtrTy(VMContext);
1586    Value *Casted = Builder.CreateBitCast(Ptr, i8Ty);
1587    Value *Res = Builder.CreateGEP(Casted, Idx, "add.ptr");
1588    return Builder.CreateBitCast(Res, Ptr->getType());
1589  }
1590
1591  return Builder.CreateInBoundsGEP(Ptr, Idx, "add.ptr");
1592}
1593
1594Value *ScalarExprEmitter::EmitSub(const BinOpInfo &Ops) {
1595  if (!isa<llvm::PointerType>(Ops.LHS->getType())) {
1596    if (Ops.Ty->isSignedIntegerType()) {
1597      switch (CGF.getContext().getLangOptions().getSignedOverflowBehavior()) {
1598      case LangOptions::SOB_Undefined:
1599        return Builder.CreateNSWSub(Ops.LHS, Ops.RHS, "sub");
1600      case LangOptions::SOB_Defined:
1601        return Builder.CreateSub(Ops.LHS, Ops.RHS, "sub");
1602      case LangOptions::SOB_Trapping:
1603        return EmitOverflowCheckedBinOp(Ops);
1604      }
1605    }
1606
1607    if (Ops.LHS->getType()->isFPOrFPVectorTy())
1608      return Builder.CreateFSub(Ops.LHS, Ops.RHS, "sub");
1609
1610    return Builder.CreateSub(Ops.LHS, Ops.RHS, "sub");
1611  }
1612
1613  // Must have binary (not unary) expr here.  Unary pointer increment doesn't
1614  // use this path.
1615  const BinaryOperator *BinOp = cast<BinaryOperator>(Ops.E);
1616
1617  if (BinOp->getLHS()->getType()->isPointerType() &&
1618      BinOp->getLHS()->getType()->getAs<PointerType>()->isVariableArrayType()) {
1619    // The amount of the addition needs to account for the VLA size for
1620    // ptr-int
1621    // The amount of the division needs to account for the VLA size for
1622    // ptr-ptr.
1623    CGF.ErrorUnsupported(BinOp, "VLA pointer subtraction");
1624  }
1625
1626  const QualType LHSType = BinOp->getLHS()->getType();
1627  const QualType LHSElementType = LHSType->getPointeeType();
1628  if (!isa<llvm::PointerType>(Ops.RHS->getType())) {
1629    // pointer - int
1630    Value *Idx = Ops.RHS;
1631    unsigned Width = cast<llvm::IntegerType>(Idx->getType())->getBitWidth();
1632    if (Width < CGF.LLVMPointerWidth) {
1633      // Zero or sign extend the pointer value based on whether the index is
1634      // signed or not.
1635      const llvm::Type *IdxType = CGF.IntPtrTy;
1636      if (BinOp->getRHS()->getType()->isSignedIntegerType())
1637        Idx = Builder.CreateSExt(Idx, IdxType, "idx.ext");
1638      else
1639        Idx = Builder.CreateZExt(Idx, IdxType, "idx.ext");
1640    }
1641    Idx = Builder.CreateNeg(Idx, "sub.ptr.neg");
1642
1643    // Handle interface types, which are not represented with a concrete type.
1644    if (const ObjCObjectType *OIT = LHSElementType->getAs<ObjCObjectType>()) {
1645      llvm::Value *InterfaceSize =
1646        llvm::ConstantInt::get(Idx->getType(),
1647                               CGF.getContext().
1648                                 getTypeSizeInChars(OIT).getQuantity());
1649      Idx = Builder.CreateMul(Idx, InterfaceSize);
1650      const llvm::Type *i8Ty = llvm::Type::getInt8PtrTy(VMContext);
1651      Value *LHSCasted = Builder.CreateBitCast(Ops.LHS, i8Ty);
1652      Value *Res = Builder.CreateGEP(LHSCasted, Idx, "add.ptr");
1653      return Builder.CreateBitCast(Res, Ops.LHS->getType());
1654    }
1655
1656    // Explicitly handle GNU void* and function pointer arithmetic
1657    // extensions. The GNU void* casts amount to no-ops since our void* type is
1658    // i8*, but this is future proof.
1659    if (LHSElementType->isVoidType() || LHSElementType->isFunctionType()) {
1660      const llvm::Type *i8Ty = llvm::Type::getInt8PtrTy(VMContext);
1661      Value *LHSCasted = Builder.CreateBitCast(Ops.LHS, i8Ty);
1662      Value *Res = Builder.CreateGEP(LHSCasted, Idx, "sub.ptr");
1663      return Builder.CreateBitCast(Res, Ops.LHS->getType());
1664    }
1665
1666    return Builder.CreateInBoundsGEP(Ops.LHS, Idx, "sub.ptr");
1667  } else {
1668    // pointer - pointer
1669    Value *LHS = Ops.LHS;
1670    Value *RHS = Ops.RHS;
1671
1672    CharUnits ElementSize;
1673
1674    // Handle GCC extension for pointer arithmetic on void* and function pointer
1675    // types.
1676    if (LHSElementType->isVoidType() || LHSElementType->isFunctionType()) {
1677      ElementSize = CharUnits::One();
1678    } else {
1679      ElementSize = CGF.getContext().getTypeSizeInChars(LHSElementType);
1680    }
1681
1682    const llvm::Type *ResultType = ConvertType(Ops.Ty);
1683    LHS = Builder.CreatePtrToInt(LHS, ResultType, "sub.ptr.lhs.cast");
1684    RHS = Builder.CreatePtrToInt(RHS, ResultType, "sub.ptr.rhs.cast");
1685    Value *BytesBetween = Builder.CreateSub(LHS, RHS, "sub.ptr.sub");
1686
1687    // Optimize out the shift for element size of 1.
1688    if (ElementSize.isOne())
1689      return BytesBetween;
1690
1691    // Otherwise, do a full sdiv. This uses the "exact" form of sdiv, since
1692    // pointer difference in C is only defined in the case where both operands
1693    // are pointing to elements of an array.
1694    Value *BytesPerElt =
1695        llvm::ConstantInt::get(ResultType, ElementSize.getQuantity());
1696    return Builder.CreateExactSDiv(BytesBetween, BytesPerElt, "sub.ptr.div");
1697  }
1698}
1699
1700Value *ScalarExprEmitter::EmitShl(const BinOpInfo &Ops) {
1701  // LLVM requires the LHS and RHS to be the same type: promote or truncate the
1702  // RHS to the same size as the LHS.
1703  Value *RHS = Ops.RHS;
1704  if (Ops.LHS->getType() != RHS->getType())
1705    RHS = Builder.CreateIntCast(RHS, Ops.LHS->getType(), false, "sh_prom");
1706
1707  if (CGF.CatchUndefined
1708      && isa<llvm::IntegerType>(Ops.LHS->getType())) {
1709    unsigned Width = cast<llvm::IntegerType>(Ops.LHS->getType())->getBitWidth();
1710    llvm::BasicBlock *Cont = CGF.createBasicBlock("cont");
1711    CGF.Builder.CreateCondBr(Builder.CreateICmpULT(RHS,
1712                                 llvm::ConstantInt::get(RHS->getType(), Width)),
1713                             Cont, CGF.getTrapBB());
1714    CGF.EmitBlock(Cont);
1715  }
1716
1717  return Builder.CreateShl(Ops.LHS, RHS, "shl");
1718}
1719
1720Value *ScalarExprEmitter::EmitShr(const BinOpInfo &Ops) {
1721  // LLVM requires the LHS and RHS to be the same type: promote or truncate the
1722  // RHS to the same size as the LHS.
1723  Value *RHS = Ops.RHS;
1724  if (Ops.LHS->getType() != RHS->getType())
1725    RHS = Builder.CreateIntCast(RHS, Ops.LHS->getType(), false, "sh_prom");
1726
1727  if (CGF.CatchUndefined
1728      && isa<llvm::IntegerType>(Ops.LHS->getType())) {
1729    unsigned Width = cast<llvm::IntegerType>(Ops.LHS->getType())->getBitWidth();
1730    llvm::BasicBlock *Cont = CGF.createBasicBlock("cont");
1731    CGF.Builder.CreateCondBr(Builder.CreateICmpULT(RHS,
1732                                 llvm::ConstantInt::get(RHS->getType(), Width)),
1733                             Cont, CGF.getTrapBB());
1734    CGF.EmitBlock(Cont);
1735  }
1736
1737  if (Ops.Ty->isUnsignedIntegerType())
1738    return Builder.CreateLShr(Ops.LHS, RHS, "shr");
1739  return Builder.CreateAShr(Ops.LHS, RHS, "shr");
1740}
1741
1742Value *ScalarExprEmitter::EmitCompare(const BinaryOperator *E,unsigned UICmpOpc,
1743                                      unsigned SICmpOpc, unsigned FCmpOpc) {
1744  TestAndClearIgnoreResultAssign();
1745  Value *Result;
1746  QualType LHSTy = E->getLHS()->getType();
1747  if (LHSTy->isMemberFunctionPointerType()) {
1748    Value *LHSPtr = CGF.EmitAnyExprToTemp(E->getLHS()).getAggregateAddr();
1749    Value *RHSPtr = CGF.EmitAnyExprToTemp(E->getRHS()).getAggregateAddr();
1750    llvm::Value *LHSFunc = Builder.CreateStructGEP(LHSPtr, 0);
1751    LHSFunc = Builder.CreateLoad(LHSFunc);
1752    llvm::Value *RHSFunc = Builder.CreateStructGEP(RHSPtr, 0);
1753    RHSFunc = Builder.CreateLoad(RHSFunc);
1754    Value *ResultF = Builder.CreateICmp((llvm::ICmpInst::Predicate)UICmpOpc,
1755                                        LHSFunc, RHSFunc, "cmp.func");
1756    Value *NullPtr = llvm::Constant::getNullValue(LHSFunc->getType());
1757    Value *ResultNull = Builder.CreateICmp((llvm::ICmpInst::Predicate)UICmpOpc,
1758                                           LHSFunc, NullPtr, "cmp.null");
1759    llvm::Value *LHSAdj = Builder.CreateStructGEP(LHSPtr, 1);
1760    LHSAdj = Builder.CreateLoad(LHSAdj);
1761    llvm::Value *RHSAdj = Builder.CreateStructGEP(RHSPtr, 1);
1762    RHSAdj = Builder.CreateLoad(RHSAdj);
1763    Value *ResultA = Builder.CreateICmp((llvm::ICmpInst::Predicate)UICmpOpc,
1764                                        LHSAdj, RHSAdj, "cmp.adj");
1765    if (E->getOpcode() == BinaryOperator::EQ) {
1766      Result = Builder.CreateOr(ResultNull, ResultA, "or.na");
1767      Result = Builder.CreateAnd(Result, ResultF, "and.f");
1768    } else {
1769      assert(E->getOpcode() == BinaryOperator::NE &&
1770             "Member pointer comparison other than == or != ?");
1771      Result = Builder.CreateAnd(ResultNull, ResultA, "and.na");
1772      Result = Builder.CreateOr(Result, ResultF, "or.f");
1773    }
1774  } else if (!LHSTy->isAnyComplexType()) {
1775    Value *LHS = Visit(E->getLHS());
1776    Value *RHS = Visit(E->getRHS());
1777
1778    if (LHS->getType()->isFPOrFPVectorTy()) {
1779      Result = Builder.CreateFCmp((llvm::CmpInst::Predicate)FCmpOpc,
1780                                  LHS, RHS, "cmp");
1781    } else if (LHSTy->isSignedIntegerType()) {
1782      Result = Builder.CreateICmp((llvm::ICmpInst::Predicate)SICmpOpc,
1783                                  LHS, RHS, "cmp");
1784    } else {
1785      // Unsigned integers and pointers.
1786      Result = Builder.CreateICmp((llvm::ICmpInst::Predicate)UICmpOpc,
1787                                  LHS, RHS, "cmp");
1788    }
1789
1790    // If this is a vector comparison, sign extend the result to the appropriate
1791    // vector integer type and return it (don't convert to bool).
1792    if (LHSTy->isVectorType())
1793      return Builder.CreateSExt(Result, ConvertType(E->getType()), "sext");
1794
1795  } else {
1796    // Complex Comparison: can only be an equality comparison.
1797    CodeGenFunction::ComplexPairTy LHS = CGF.EmitComplexExpr(E->getLHS());
1798    CodeGenFunction::ComplexPairTy RHS = CGF.EmitComplexExpr(E->getRHS());
1799
1800    QualType CETy = LHSTy->getAs<ComplexType>()->getElementType();
1801
1802    Value *ResultR, *ResultI;
1803    if (CETy->isRealFloatingType()) {
1804      ResultR = Builder.CreateFCmp((llvm::FCmpInst::Predicate)FCmpOpc,
1805                                   LHS.first, RHS.first, "cmp.r");
1806      ResultI = Builder.CreateFCmp((llvm::FCmpInst::Predicate)FCmpOpc,
1807                                   LHS.second, RHS.second, "cmp.i");
1808    } else {
1809      // Complex comparisons can only be equality comparisons.  As such, signed
1810      // and unsigned opcodes are the same.
1811      ResultR = Builder.CreateICmp((llvm::ICmpInst::Predicate)UICmpOpc,
1812                                   LHS.first, RHS.first, "cmp.r");
1813      ResultI = Builder.CreateICmp((llvm::ICmpInst::Predicate)UICmpOpc,
1814                                   LHS.second, RHS.second, "cmp.i");
1815    }
1816
1817    if (E->getOpcode() == BinaryOperator::EQ) {
1818      Result = Builder.CreateAnd(ResultR, ResultI, "and.ri");
1819    } else {
1820      assert(E->getOpcode() == BinaryOperator::NE &&
1821             "Complex comparison other than == or != ?");
1822      Result = Builder.CreateOr(ResultR, ResultI, "or.ri");
1823    }
1824  }
1825
1826  return EmitScalarConversion(Result, CGF.getContext().BoolTy, E->getType());
1827}
1828
1829Value *ScalarExprEmitter::VisitBinAssign(const BinaryOperator *E) {
1830  bool Ignore = TestAndClearIgnoreResultAssign();
1831
1832  // __block variables need to have the rhs evaluated first, plus this should
1833  // improve codegen just a little.
1834  Value *RHS = Visit(E->getRHS());
1835  LValue LHS = EmitCheckedLValue(E->getLHS());
1836
1837  // Store the value into the LHS.  Bit-fields are handled specially
1838  // because the result is altered by the store, i.e., [C99 6.5.16p1]
1839  // 'An assignment expression has the value of the left operand after
1840  // the assignment...'.
1841  if (LHS.isBitField()) {
1842    if (!LHS.isVolatileQualified()) {
1843      CGF.EmitStoreThroughBitfieldLValue(RValue::get(RHS), LHS, E->getType(),
1844                                         &RHS);
1845      return RHS;
1846    } else
1847      CGF.EmitStoreThroughBitfieldLValue(RValue::get(RHS), LHS, E->getType());
1848  } else
1849    CGF.EmitStoreThroughLValue(RValue::get(RHS), LHS, E->getType());
1850  if (Ignore)
1851    return 0;
1852  return EmitLoadOfLValue(LHS, E->getType());
1853}
1854
1855Value *ScalarExprEmitter::VisitBinLAnd(const BinaryOperator *E) {
1856  const llvm::Type *ResTy = ConvertType(E->getType());
1857
1858  // If we have 0 && RHS, see if we can elide RHS, if so, just return 0.
1859  // If we have 1 && X, just emit X without inserting the control flow.
1860  if (int Cond = CGF.ConstantFoldsToSimpleInteger(E->getLHS())) {
1861    if (Cond == 1) { // If we have 1 && X, just emit X.
1862      Value *RHSCond = CGF.EvaluateExprAsBool(E->getRHS());
1863      // ZExt result to int or bool.
1864      return Builder.CreateZExtOrBitCast(RHSCond, ResTy, "land.ext");
1865    }
1866
1867    // 0 && RHS: If it is safe, just elide the RHS, and return 0/false.
1868    if (!CGF.ContainsLabel(E->getRHS()))
1869      return llvm::Constant::getNullValue(ResTy);
1870  }
1871
1872  llvm::BasicBlock *ContBlock = CGF.createBasicBlock("land.end");
1873  llvm::BasicBlock *RHSBlock  = CGF.createBasicBlock("land.rhs");
1874
1875  // Branch on the LHS first.  If it is false, go to the failure (cont) block.
1876  CGF.EmitBranchOnBoolExpr(E->getLHS(), RHSBlock, ContBlock);
1877
1878  // Any edges into the ContBlock are now from an (indeterminate number of)
1879  // edges from this first condition.  All of these values will be false.  Start
1880  // setting up the PHI node in the Cont Block for this.
1881  llvm::PHINode *PN = llvm::PHINode::Create(llvm::Type::getInt1Ty(VMContext),
1882                                            "", ContBlock);
1883  PN->reserveOperandSpace(2);  // Normal case, two inputs.
1884  for (llvm::pred_iterator PI = pred_begin(ContBlock), PE = pred_end(ContBlock);
1885       PI != PE; ++PI)
1886    PN->addIncoming(llvm::ConstantInt::getFalse(VMContext), *PI);
1887
1888  CGF.BeginConditionalBranch();
1889  CGF.EmitBlock(RHSBlock);
1890  Value *RHSCond = CGF.EvaluateExprAsBool(E->getRHS());
1891  CGF.EndConditionalBranch();
1892
1893  // Reaquire the RHS block, as there may be subblocks inserted.
1894  RHSBlock = Builder.GetInsertBlock();
1895
1896  // Emit an unconditional branch from this block to ContBlock.  Insert an entry
1897  // into the phi node for the edge with the value of RHSCond.
1898  CGF.EmitBlock(ContBlock);
1899  PN->addIncoming(RHSCond, RHSBlock);
1900
1901  // ZExt result to int.
1902  return Builder.CreateZExtOrBitCast(PN, ResTy, "land.ext");
1903}
1904
1905Value *ScalarExprEmitter::VisitBinLOr(const BinaryOperator *E) {
1906  const llvm::Type *ResTy = ConvertType(E->getType());
1907
1908  // If we have 1 || RHS, see if we can elide RHS, if so, just return 1.
1909  // If we have 0 || X, just emit X without inserting the control flow.
1910  if (int Cond = CGF.ConstantFoldsToSimpleInteger(E->getLHS())) {
1911    if (Cond == -1) { // If we have 0 || X, just emit X.
1912      Value *RHSCond = CGF.EvaluateExprAsBool(E->getRHS());
1913      // ZExt result to int or bool.
1914      return Builder.CreateZExtOrBitCast(RHSCond, ResTy, "lor.ext");
1915    }
1916
1917    // 1 || RHS: If it is safe, just elide the RHS, and return 1/true.
1918    if (!CGF.ContainsLabel(E->getRHS()))
1919      return llvm::ConstantInt::get(ResTy, 1);
1920  }
1921
1922  llvm::BasicBlock *ContBlock = CGF.createBasicBlock("lor.end");
1923  llvm::BasicBlock *RHSBlock = CGF.createBasicBlock("lor.rhs");
1924
1925  // Branch on the LHS first.  If it is true, go to the success (cont) block.
1926  CGF.EmitBranchOnBoolExpr(E->getLHS(), ContBlock, RHSBlock);
1927
1928  // Any edges into the ContBlock are now from an (indeterminate number of)
1929  // edges from this first condition.  All of these values will be true.  Start
1930  // setting up the PHI node in the Cont Block for this.
1931  llvm::PHINode *PN = llvm::PHINode::Create(llvm::Type::getInt1Ty(VMContext),
1932                                            "", ContBlock);
1933  PN->reserveOperandSpace(2);  // Normal case, two inputs.
1934  for (llvm::pred_iterator PI = pred_begin(ContBlock), PE = pred_end(ContBlock);
1935       PI != PE; ++PI)
1936    PN->addIncoming(llvm::ConstantInt::getTrue(VMContext), *PI);
1937
1938  CGF.BeginConditionalBranch();
1939
1940  // Emit the RHS condition as a bool value.
1941  CGF.EmitBlock(RHSBlock);
1942  Value *RHSCond = CGF.EvaluateExprAsBool(E->getRHS());
1943
1944  CGF.EndConditionalBranch();
1945
1946  // Reaquire the RHS block, as there may be subblocks inserted.
1947  RHSBlock = Builder.GetInsertBlock();
1948
1949  // Emit an unconditional branch from this block to ContBlock.  Insert an entry
1950  // into the phi node for the edge with the value of RHSCond.
1951  CGF.EmitBlock(ContBlock);
1952  PN->addIncoming(RHSCond, RHSBlock);
1953
1954  // ZExt result to int.
1955  return Builder.CreateZExtOrBitCast(PN, ResTy, "lor.ext");
1956}
1957
1958Value *ScalarExprEmitter::VisitBinComma(const BinaryOperator *E) {
1959  CGF.EmitStmt(E->getLHS());
1960  CGF.EnsureInsertPoint();
1961  return Visit(E->getRHS());
1962}
1963
1964//===----------------------------------------------------------------------===//
1965//                             Other Operators
1966//===----------------------------------------------------------------------===//
1967
1968/// isCheapEnoughToEvaluateUnconditionally - Return true if the specified
1969/// expression is cheap enough and side-effect-free enough to evaluate
1970/// unconditionally instead of conditionally.  This is used to convert control
1971/// flow into selects in some cases.
1972static bool isCheapEnoughToEvaluateUnconditionally(const Expr *E,
1973                                                   CodeGenFunction &CGF) {
1974  if (const ParenExpr *PE = dyn_cast<ParenExpr>(E))
1975    return isCheapEnoughToEvaluateUnconditionally(PE->getSubExpr(), CGF);
1976
1977  // TODO: Allow anything we can constant fold to an integer or fp constant.
1978  if (isa<IntegerLiteral>(E) || isa<CharacterLiteral>(E) ||
1979      isa<FloatingLiteral>(E))
1980    return true;
1981
1982  // Non-volatile automatic variables too, to get "cond ? X : Y" where
1983  // X and Y are local variables.
1984  if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
1985    if (const VarDecl *VD = dyn_cast<VarDecl>(DRE->getDecl()))
1986      if (VD->hasLocalStorage() && !(CGF.getContext()
1987                                     .getCanonicalType(VD->getType())
1988                                     .isVolatileQualified()))
1989        return true;
1990
1991  return false;
1992}
1993
1994
1995Value *ScalarExprEmitter::
1996VisitConditionalOperator(const ConditionalOperator *E) {
1997  TestAndClearIgnoreResultAssign();
1998  // If the condition constant folds and can be elided, try to avoid emitting
1999  // the condition and the dead arm.
2000  if (int Cond = CGF.ConstantFoldsToSimpleInteger(E->getCond())){
2001    Expr *Live = E->getLHS(), *Dead = E->getRHS();
2002    if (Cond == -1)
2003      std::swap(Live, Dead);
2004
2005    // If the dead side doesn't have labels we need, and if the Live side isn't
2006    // the gnu missing ?: extension (which we could handle, but don't bother
2007    // to), just emit the Live part.
2008    if ((!Dead || !CGF.ContainsLabel(Dead)) &&  // No labels in dead part
2009        Live)                                   // Live part isn't missing.
2010      return Visit(Live);
2011  }
2012
2013
2014  // If this is a really simple expression (like x ? 4 : 5), emit this as a
2015  // select instead of as control flow.  We can only do this if it is cheap and
2016  // safe to evaluate the LHS and RHS unconditionally.
2017  if (E->getLHS() && isCheapEnoughToEvaluateUnconditionally(E->getLHS(),
2018                                                            CGF) &&
2019      isCheapEnoughToEvaluateUnconditionally(E->getRHS(), CGF)) {
2020    llvm::Value *CondV = CGF.EvaluateExprAsBool(E->getCond());
2021    llvm::Value *LHS = Visit(E->getLHS());
2022    llvm::Value *RHS = Visit(E->getRHS());
2023    return Builder.CreateSelect(CondV, LHS, RHS, "cond");
2024  }
2025
2026
2027  llvm::BasicBlock *LHSBlock = CGF.createBasicBlock("cond.true");
2028  llvm::BasicBlock *RHSBlock = CGF.createBasicBlock("cond.false");
2029  llvm::BasicBlock *ContBlock = CGF.createBasicBlock("cond.end");
2030  Value *CondVal = 0;
2031
2032  // If we don't have the GNU missing condition extension, emit a branch on bool
2033  // the normal way.
2034  if (E->getLHS()) {
2035    // Otherwise, just use EmitBranchOnBoolExpr to get small and simple code for
2036    // the branch on bool.
2037    CGF.EmitBranchOnBoolExpr(E->getCond(), LHSBlock, RHSBlock);
2038  } else {
2039    // Otherwise, for the ?: extension, evaluate the conditional and then
2040    // convert it to bool the hard way.  We do this explicitly because we need
2041    // the unconverted value for the missing middle value of the ?:.
2042    CondVal = CGF.EmitScalarExpr(E->getCond());
2043
2044    // In some cases, EmitScalarConversion will delete the "CondVal" expression
2045    // if there are no extra uses (an optimization).  Inhibit this by making an
2046    // extra dead use, because we're going to add a use of CondVal later.  We
2047    // don't use the builder for this, because we don't want it to get optimized
2048    // away.  This leaves dead code, but the ?: extension isn't common.
2049    new llvm::BitCastInst(CondVal, CondVal->getType(), "dummy?:holder",
2050                          Builder.GetInsertBlock());
2051
2052    Value *CondBoolVal =
2053      CGF.EmitScalarConversion(CondVal, E->getCond()->getType(),
2054                               CGF.getContext().BoolTy);
2055    Builder.CreateCondBr(CondBoolVal, LHSBlock, RHSBlock);
2056  }
2057
2058  CGF.BeginConditionalBranch();
2059  CGF.EmitBlock(LHSBlock);
2060
2061  // Handle the GNU extension for missing LHS.
2062  Value *LHS;
2063  if (E->getLHS())
2064    LHS = Visit(E->getLHS());
2065  else    // Perform promotions, to handle cases like "short ?: int"
2066    LHS = EmitScalarConversion(CondVal, E->getCond()->getType(), E->getType());
2067
2068  CGF.EndConditionalBranch();
2069  LHSBlock = Builder.GetInsertBlock();
2070  CGF.EmitBranch(ContBlock);
2071
2072  CGF.BeginConditionalBranch();
2073  CGF.EmitBlock(RHSBlock);
2074
2075  Value *RHS = Visit(E->getRHS());
2076  CGF.EndConditionalBranch();
2077  RHSBlock = Builder.GetInsertBlock();
2078  CGF.EmitBranch(ContBlock);
2079
2080  CGF.EmitBlock(ContBlock);
2081
2082  // If the LHS or RHS is a throw expression, it will be legitimately null.
2083  if (!LHS)
2084    return RHS;
2085  if (!RHS)
2086    return LHS;
2087
2088  // Create a PHI node for the real part.
2089  llvm::PHINode *PN = Builder.CreatePHI(LHS->getType(), "cond");
2090  PN->reserveOperandSpace(2);
2091  PN->addIncoming(LHS, LHSBlock);
2092  PN->addIncoming(RHS, RHSBlock);
2093  return PN;
2094}
2095
2096Value *ScalarExprEmitter::VisitChooseExpr(ChooseExpr *E) {
2097  return Visit(E->getChosenSubExpr(CGF.getContext()));
2098}
2099
2100Value *ScalarExprEmitter::VisitVAArgExpr(VAArgExpr *VE) {
2101  llvm::Value *ArgValue = CGF.EmitVAListRef(VE->getSubExpr());
2102  llvm::Value *ArgPtr = CGF.EmitVAArg(ArgValue, VE->getType());
2103
2104  // If EmitVAArg fails, we fall back to the LLVM instruction.
2105  if (!ArgPtr)
2106    return Builder.CreateVAArg(ArgValue, ConvertType(VE->getType()));
2107
2108  // FIXME Volatility.
2109  return Builder.CreateLoad(ArgPtr);
2110}
2111
2112Value *ScalarExprEmitter::VisitBlockExpr(const BlockExpr *BE) {
2113  return CGF.BuildBlockLiteralTmp(BE);
2114}
2115
2116//===----------------------------------------------------------------------===//
2117//                         Entry Point into this File
2118//===----------------------------------------------------------------------===//
2119
2120/// EmitScalarExpr - Emit the computation of the specified expression of scalar
2121/// type, ignoring the result.
2122Value *CodeGenFunction::EmitScalarExpr(const Expr *E, bool IgnoreResultAssign) {
2123  assert(E && !hasAggregateLLVMType(E->getType()) &&
2124         "Invalid scalar expression to emit");
2125
2126  return ScalarExprEmitter(*this, IgnoreResultAssign)
2127    .Visit(const_cast<Expr*>(E));
2128}
2129
2130/// EmitScalarConversion - Emit a conversion from the specified type to the
2131/// specified destination type, both of which are LLVM scalar types.
2132Value *CodeGenFunction::EmitScalarConversion(Value *Src, QualType SrcTy,
2133                                             QualType DstTy) {
2134  assert(!hasAggregateLLVMType(SrcTy) && !hasAggregateLLVMType(DstTy) &&
2135         "Invalid scalar expression to emit");
2136  return ScalarExprEmitter(*this).EmitScalarConversion(Src, SrcTy, DstTy);
2137}
2138
2139/// EmitComplexToScalarConversion - Emit a conversion from the specified complex
2140/// type to the specified destination type, where the destination type is an
2141/// LLVM scalar type.
2142Value *CodeGenFunction::EmitComplexToScalarConversion(ComplexPairTy Src,
2143                                                      QualType SrcTy,
2144                                                      QualType DstTy) {
2145  assert(SrcTy->isAnyComplexType() && !hasAggregateLLVMType(DstTy) &&
2146         "Invalid complex -> scalar conversion");
2147  return ScalarExprEmitter(*this).EmitComplexToScalarConversion(Src, SrcTy,
2148                                                                DstTy);
2149}
2150
2151
2152llvm::Value *CodeGenFunction::
2153EmitScalarPrePostIncDec(const UnaryOperator *E, LValue LV,
2154                        bool isInc, bool isPre) {
2155  return ScalarExprEmitter(*this).EmitScalarPrePostIncDec(E, LV, isInc, isPre);
2156}
2157
2158LValue CodeGenFunction::EmitObjCIsaExpr(const ObjCIsaExpr *E) {
2159  llvm::Value *V;
2160  // object->isa or (*object).isa
2161  // Generate code as for: *(Class*)object
2162  // build Class* type
2163  const llvm::Type *ClassPtrTy = ConvertType(E->getType());
2164
2165  Expr *BaseExpr = E->getBase();
2166  if (BaseExpr->isLvalue(getContext()) != Expr::LV_Valid) {
2167    V = CreateTempAlloca(ClassPtrTy, "resval");
2168    llvm::Value *Src = EmitScalarExpr(BaseExpr);
2169    Builder.CreateStore(Src, V);
2170    LValue LV = LValue::MakeAddr(V, MakeQualifiers(E->getType()));
2171    V = ScalarExprEmitter(*this).EmitLoadOfLValue(LV, E->getType());
2172  }
2173  else {
2174      if (E->isArrow())
2175        V = ScalarExprEmitter(*this).EmitLoadOfLValue(BaseExpr);
2176      else
2177        V  = EmitLValue(BaseExpr).getAddress();
2178  }
2179
2180  // build Class* type
2181  ClassPtrTy = ClassPtrTy->getPointerTo();
2182  V = Builder.CreateBitCast(V, ClassPtrTy);
2183  LValue LV = LValue::MakeAddr(V, MakeQualifiers(E->getType()));
2184  return LV;
2185}
2186
2187
2188LValue CodeGenFunction::EmitCompoundAssignOperatorLValue(
2189                                            const CompoundAssignOperator *E) {
2190  ScalarExprEmitter Scalar(*this);
2191  Value *BitFieldResult = 0;
2192  switch (E->getOpcode()) {
2193#define COMPOUND_OP(Op)                                                       \
2194    case BinaryOperator::Op##Assign:                                          \
2195      return Scalar.EmitCompoundAssignLValue(E, &ScalarExprEmitter::Emit##Op, \
2196                                             BitFieldResult)
2197  COMPOUND_OP(Mul);
2198  COMPOUND_OP(Div);
2199  COMPOUND_OP(Rem);
2200  COMPOUND_OP(Add);
2201  COMPOUND_OP(Sub);
2202  COMPOUND_OP(Shl);
2203  COMPOUND_OP(Shr);
2204  COMPOUND_OP(And);
2205  COMPOUND_OP(Xor);
2206  COMPOUND_OP(Or);
2207#undef COMPOUND_OP
2208
2209  case BinaryOperator::PtrMemD:
2210  case BinaryOperator::PtrMemI:
2211  case BinaryOperator::Mul:
2212  case BinaryOperator::Div:
2213  case BinaryOperator::Rem:
2214  case BinaryOperator::Add:
2215  case BinaryOperator::Sub:
2216  case BinaryOperator::Shl:
2217  case BinaryOperator::Shr:
2218  case BinaryOperator::LT:
2219  case BinaryOperator::GT:
2220  case BinaryOperator::LE:
2221  case BinaryOperator::GE:
2222  case BinaryOperator::EQ:
2223  case BinaryOperator::NE:
2224  case BinaryOperator::And:
2225  case BinaryOperator::Xor:
2226  case BinaryOperator::Or:
2227  case BinaryOperator::LAnd:
2228  case BinaryOperator::LOr:
2229  case BinaryOperator::Assign:
2230  case BinaryOperator::Comma:
2231    assert(false && "Not valid compound assignment operators");
2232    break;
2233  }
2234
2235  llvm_unreachable("Unhandled compound assignment operator");
2236}
2237