CGExprScalar.cpp revision 569c3166874324c24011f8ade6978421f0d39b3c 
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 *VisitCXXScalarValueInitExpr(const CXXScalarValueInitExpr *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(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->hasSignedIntegerRepresentation()) {
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 *&Result);
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 glvalue casts are never null.
901    if (ICE->getCategory() != ImplicitCastExpr::RValue)
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_LValueBitCast:
929  case CastExpr::CK_ObjCObjectLValueCast: {
930    Value *V = EmitLValue(E).getAddress();
931    V = Builder.CreateBitCast(V,
932                          ConvertType(CGF.getContext().getPointerType(DestTy)));
933    // FIXME: Are the qualifiers correct here?
934    return EmitLoadOfLValue(LValue::MakeAddr(V, CGF.MakeQualifiers(DestTy)),
935                            DestTy);
936  }
937
938  case CastExpr::CK_AnyPointerToObjCPointerCast:
939  case CastExpr::CK_AnyPointerToBlockPointerCast:
940  case CastExpr::CK_BitCast: {
941    Value *Src = Visit(const_cast<Expr*>(E));
942    return Builder.CreateBitCast(Src, ConvertType(DestTy));
943  }
944  case CastExpr::CK_NoOp:
945  case CastExpr::CK_UserDefinedConversion:
946    return Visit(const_cast<Expr*>(E));
947
948  case CastExpr::CK_BaseToDerived: {
949    const CXXRecordDecl *DerivedClassDecl =
950      DestTy->getCXXRecordDeclForPointerType();
951
952    return CGF.GetAddressOfDerivedClass(Visit(E), DerivedClassDecl,
953                                        CE->path_begin(), CE->path_end(),
954                                        ShouldNullCheckClassCastValue(CE));
955  }
956  case CastExpr::CK_UncheckedDerivedToBase:
957  case CastExpr::CK_DerivedToBase: {
958    const RecordType *DerivedClassTy =
959      E->getType()->getAs<PointerType>()->getPointeeType()->getAs<RecordType>();
960    CXXRecordDecl *DerivedClassDecl =
961      cast<CXXRecordDecl>(DerivedClassTy->getDecl());
962
963    return CGF.GetAddressOfBaseClass(Visit(E), DerivedClassDecl,
964                                     CE->path_begin(), CE->path_end(),
965                                     ShouldNullCheckClassCastValue(CE));
966  }
967  case CastExpr::CK_Dynamic: {
968    Value *V = Visit(const_cast<Expr*>(E));
969    const CXXDynamicCastExpr *DCE = cast<CXXDynamicCastExpr>(CE);
970    return CGF.EmitDynamicCast(V, DCE);
971  }
972  case CastExpr::CK_ToUnion:
973    assert(0 && "Should be unreachable!");
974    break;
975
976  case CastExpr::CK_ArrayToPointerDecay: {
977    assert(E->getType()->isArrayType() &&
978           "Array to pointer decay must have array source type!");
979
980    Value *V = EmitLValue(E).getAddress();  // Bitfields can't be arrays.
981
982    // Note that VLA pointers are always decayed, so we don't need to do
983    // anything here.
984    if (!E->getType()->isVariableArrayType()) {
985      assert(isa<llvm::PointerType>(V->getType()) && "Expected pointer");
986      assert(isa<llvm::ArrayType>(cast<llvm::PointerType>(V->getType())
987                                 ->getElementType()) &&
988             "Expected pointer to array");
989      V = Builder.CreateStructGEP(V, 0, "arraydecay");
990    }
991
992    return V;
993  }
994  case CastExpr::CK_FunctionToPointerDecay:
995    return EmitLValue(E).getAddress();
996
997  case CastExpr::CK_NullToMemberPointer:
998    return CGF.CGM.EmitNullConstant(DestTy);
999
1000  case CastExpr::CK_BaseToDerivedMemberPointer:
1001  case CastExpr::CK_DerivedToBaseMemberPointer: {
1002    Value *Src = Visit(E);
1003
1004    // See if we need to adjust the pointer.
1005    const CXXRecordDecl *BaseDecl =
1006      cast<CXXRecordDecl>(E->getType()->getAs<MemberPointerType>()->
1007                          getClass()->getAs<RecordType>()->getDecl());
1008    const CXXRecordDecl *DerivedDecl =
1009      cast<CXXRecordDecl>(CE->getType()->getAs<MemberPointerType>()->
1010                          getClass()->getAs<RecordType>()->getDecl());
1011    if (CE->getCastKind() == CastExpr::CK_DerivedToBaseMemberPointer)
1012      std::swap(DerivedDecl, BaseDecl);
1013
1014    if (llvm::Constant *Adj =
1015          CGF.CGM.GetNonVirtualBaseClassOffset(DerivedDecl,
1016                                               CE->path_begin(),
1017                                               CE->path_end())) {
1018      if (CE->getCastKind() == CastExpr::CK_DerivedToBaseMemberPointer)
1019        Src = Builder.CreateNSWSub(Src, Adj, "adj");
1020      else
1021        Src = Builder.CreateNSWAdd(Src, Adj, "adj");
1022    }
1023
1024    return Src;
1025  }
1026
1027  case CastExpr::CK_ConstructorConversion:
1028    assert(0 && "Should be unreachable!");
1029    break;
1030
1031  case CastExpr::CK_IntegralToPointer: {
1032    Value *Src = Visit(const_cast<Expr*>(E));
1033
1034    // First, convert to the correct width so that we control the kind of
1035    // extension.
1036    const llvm::Type *MiddleTy = CGF.IntPtrTy;
1037    bool InputSigned = E->getType()->isSignedIntegerType();
1038    llvm::Value* IntResult =
1039      Builder.CreateIntCast(Src, MiddleTy, InputSigned, "conv");
1040
1041    return Builder.CreateIntToPtr(IntResult, ConvertType(DestTy));
1042  }
1043  case CastExpr::CK_PointerToIntegral: {
1044    Value *Src = Visit(const_cast<Expr*>(E));
1045    return Builder.CreatePtrToInt(Src, ConvertType(DestTy));
1046  }
1047  case CastExpr::CK_ToVoid: {
1048    if (E->Classify(CGF.getContext()).isGLValue())
1049      CGF.EmitLValue(E);
1050    else
1051      CGF.EmitAnyExpr(E, 0, false, true);
1052    return 0;
1053  }
1054  case CastExpr::CK_VectorSplat: {
1055    const llvm::Type *DstTy = ConvertType(DestTy);
1056    Value *Elt = Visit(const_cast<Expr*>(E));
1057
1058    // Insert the element in element zero of an undef vector
1059    llvm::Value *UnV = llvm::UndefValue::get(DstTy);
1060    llvm::Value *Idx = llvm::ConstantInt::get(CGF.Int32Ty, 0);
1061    UnV = Builder.CreateInsertElement(UnV, Elt, Idx, "tmp");
1062
1063    // Splat the element across to all elements
1064    llvm::SmallVector<llvm::Constant*, 16> Args;
1065    unsigned NumElements = cast<llvm::VectorType>(DstTy)->getNumElements();
1066    for (unsigned i = 0; i < NumElements; i++)
1067      Args.push_back(llvm::ConstantInt::get(CGF.Int32Ty, 0));
1068
1069    llvm::Constant *Mask = llvm::ConstantVector::get(&Args[0], NumElements);
1070    llvm::Value *Yay = Builder.CreateShuffleVector(UnV, UnV, Mask, "splat");
1071    return Yay;
1072  }
1073  case CastExpr::CK_IntegralCast:
1074  case CastExpr::CK_IntegralToFloating:
1075  case CastExpr::CK_FloatingToIntegral:
1076  case CastExpr::CK_FloatingCast:
1077    return EmitScalarConversion(Visit(E), E->getType(), DestTy);
1078
1079  case CastExpr::CK_MemberPointerToBoolean:
1080    return CGF.EvaluateExprAsBool(E);
1081  }
1082
1083  // Handle cases where the source is an non-complex type.
1084
1085  if (!CGF.hasAggregateLLVMType(E->getType())) {
1086    Value *Src = Visit(const_cast<Expr*>(E));
1087
1088    // Use EmitScalarConversion to perform the conversion.
1089    return EmitScalarConversion(Src, E->getType(), DestTy);
1090  }
1091
1092  if (E->getType()->isAnyComplexType()) {
1093    // Handle cases where the source is a complex type.
1094    bool IgnoreImag = true;
1095    bool IgnoreImagAssign = true;
1096    bool IgnoreReal = IgnoreResultAssign;
1097    bool IgnoreRealAssign = IgnoreResultAssign;
1098    if (DestTy->isBooleanType())
1099      IgnoreImagAssign = IgnoreImag = false;
1100    else if (DestTy->isVoidType()) {
1101      IgnoreReal = IgnoreImag = false;
1102      IgnoreRealAssign = IgnoreImagAssign = true;
1103    }
1104    CodeGenFunction::ComplexPairTy V
1105      = CGF.EmitComplexExpr(E, IgnoreReal, IgnoreImag, IgnoreRealAssign,
1106                            IgnoreImagAssign);
1107    return EmitComplexToScalarConversion(V, E->getType(), DestTy);
1108  }
1109
1110  // Okay, this is a cast from an aggregate.  It must be a cast to void.  Just
1111  // evaluate the result and return.
1112  CGF.EmitAggExpr(E, 0, false, true);
1113  return 0;
1114}
1115
1116Value *ScalarExprEmitter::VisitStmtExpr(const StmtExpr *E) {
1117  return CGF.EmitCompoundStmt(*E->getSubStmt(),
1118                              !E->getType()->isVoidType()).getScalarVal();
1119}
1120
1121Value *ScalarExprEmitter::VisitBlockDeclRefExpr(const BlockDeclRefExpr *E) {
1122  llvm::Value *V = CGF.GetAddrOfBlockDecl(E);
1123  if (E->getType().isObjCGCWeak())
1124    return CGF.CGM.getObjCRuntime().EmitObjCWeakRead(CGF, V);
1125  return Builder.CreateLoad(V, "tmp");
1126}
1127
1128//===----------------------------------------------------------------------===//
1129//                             Unary Operators
1130//===----------------------------------------------------------------------===//
1131
1132llvm::Value *ScalarExprEmitter::
1133EmitScalarPrePostIncDec(const UnaryOperator *E, LValue LV,
1134                        bool isInc, bool isPre) {
1135
1136  QualType ValTy = E->getSubExpr()->getType();
1137  llvm::Value *InVal = EmitLoadOfLValue(LV, ValTy);
1138
1139  int AmountVal = isInc ? 1 : -1;
1140
1141  if (ValTy->isPointerType() &&
1142      ValTy->getAs<PointerType>()->isVariableArrayType()) {
1143    // The amount of the addition/subtraction needs to account for the VLA size
1144    CGF.ErrorUnsupported(E, "VLA pointer inc/dec");
1145  }
1146
1147  llvm::Value *NextVal;
1148  if (const llvm::PointerType *PT =
1149      dyn_cast<llvm::PointerType>(InVal->getType())) {
1150    llvm::Constant *Inc = llvm::ConstantInt::get(CGF.Int32Ty, AmountVal);
1151    if (!isa<llvm::FunctionType>(PT->getElementType())) {
1152      QualType PTEE = ValTy->getPointeeType();
1153      if (const ObjCObjectType *OIT = PTEE->getAs<ObjCObjectType>()) {
1154        // Handle interface types, which are not represented with a concrete
1155        // type.
1156        int size = CGF.getContext().getTypeSize(OIT) / 8;
1157        if (!isInc)
1158          size = -size;
1159        Inc = llvm::ConstantInt::get(Inc->getType(), size);
1160        const llvm::Type *i8Ty = llvm::Type::getInt8PtrTy(VMContext);
1161        InVal = Builder.CreateBitCast(InVal, i8Ty);
1162        NextVal = Builder.CreateGEP(InVal, Inc, "add.ptr");
1163        llvm::Value *lhs = LV.getAddress();
1164        lhs = Builder.CreateBitCast(lhs, llvm::PointerType::getUnqual(i8Ty));
1165        LV = LValue::MakeAddr(lhs, CGF.MakeQualifiers(ValTy));
1166      } else
1167        NextVal = Builder.CreateInBoundsGEP(InVal, Inc, "ptrincdec");
1168    } else {
1169      const llvm::Type *i8Ty = llvm::Type::getInt8PtrTy(VMContext);
1170      NextVal = Builder.CreateBitCast(InVal, i8Ty, "tmp");
1171      NextVal = Builder.CreateGEP(NextVal, Inc, "ptrincdec");
1172      NextVal = Builder.CreateBitCast(NextVal, InVal->getType());
1173    }
1174  } else if (InVal->getType()->isIntegerTy(1) && isInc) {
1175    // Bool++ is an interesting case, due to promotion rules, we get:
1176    // Bool++ -> Bool = Bool+1 -> Bool = (int)Bool+1 ->
1177    // Bool = ((int)Bool+1) != 0
1178    // An interesting aspect of this is that increment is always true.
1179    // Decrement does not have this property.
1180    NextVal = llvm::ConstantInt::getTrue(VMContext);
1181  } else if (isa<llvm::IntegerType>(InVal->getType())) {
1182    NextVal = llvm::ConstantInt::get(InVal->getType(), AmountVal);
1183
1184    if (!ValTy->isSignedIntegerType())
1185      // Unsigned integer inc is always two's complement.
1186      NextVal = Builder.CreateAdd(InVal, NextVal, isInc ? "inc" : "dec");
1187    else {
1188      switch (CGF.getContext().getLangOptions().getSignedOverflowBehavior()) {
1189      case LangOptions::SOB_Undefined:
1190        NextVal = Builder.CreateNSWAdd(InVal, NextVal, isInc ? "inc" : "dec");
1191        break;
1192      case LangOptions::SOB_Defined:
1193        NextVal = Builder.CreateAdd(InVal, NextVal, isInc ? "inc" : "dec");
1194        break;
1195      case LangOptions::SOB_Trapping:
1196        BinOpInfo BinOp;
1197        BinOp.LHS = InVal;
1198        BinOp.RHS = NextVal;
1199        BinOp.Ty = E->getType();
1200        BinOp.Opcode = BinaryOperator::Add;
1201        BinOp.E = E;
1202        NextVal = EmitOverflowCheckedBinOp(BinOp);
1203        break;
1204      }
1205    }
1206  } else {
1207    // Add the inc/dec to the real part.
1208    if (InVal->getType()->isFloatTy())
1209      NextVal =
1210      llvm::ConstantFP::get(VMContext,
1211                            llvm::APFloat(static_cast<float>(AmountVal)));
1212    else if (InVal->getType()->isDoubleTy())
1213      NextVal =
1214      llvm::ConstantFP::get(VMContext,
1215                            llvm::APFloat(static_cast<double>(AmountVal)));
1216    else {
1217      llvm::APFloat F(static_cast<float>(AmountVal));
1218      bool ignored;
1219      F.convert(CGF.Target.getLongDoubleFormat(), llvm::APFloat::rmTowardZero,
1220                &ignored);
1221      NextVal = llvm::ConstantFP::get(VMContext, F);
1222    }
1223    NextVal = Builder.CreateFAdd(InVal, NextVal, isInc ? "inc" : "dec");
1224  }
1225
1226  // Store the updated result through the lvalue.
1227  if (LV.isBitField())
1228    CGF.EmitStoreThroughBitfieldLValue(RValue::get(NextVal), LV, ValTy, &NextVal);
1229  else
1230    CGF.EmitStoreThroughLValue(RValue::get(NextVal), LV, ValTy);
1231
1232  // If this is a postinc, return the value read from memory, otherwise use the
1233  // updated value.
1234  return isPre ? NextVal : InVal;
1235}
1236
1237
1238
1239Value *ScalarExprEmitter::VisitUnaryMinus(const UnaryOperator *E) {
1240  TestAndClearIgnoreResultAssign();
1241  // Emit unary minus with EmitSub so we handle overflow cases etc.
1242  BinOpInfo BinOp;
1243  BinOp.RHS = Visit(E->getSubExpr());
1244
1245  if (BinOp.RHS->getType()->isFPOrFPVectorTy())
1246    BinOp.LHS = llvm::ConstantFP::getZeroValueForNegation(BinOp.RHS->getType());
1247  else
1248    BinOp.LHS = llvm::Constant::getNullValue(BinOp.RHS->getType());
1249  BinOp.Ty = E->getType();
1250  BinOp.Opcode = BinaryOperator::Sub;
1251  BinOp.E = E;
1252  return EmitSub(BinOp);
1253}
1254
1255Value *ScalarExprEmitter::VisitUnaryNot(const UnaryOperator *E) {
1256  TestAndClearIgnoreResultAssign();
1257  Value *Op = Visit(E->getSubExpr());
1258  return Builder.CreateNot(Op, "neg");
1259}
1260
1261Value *ScalarExprEmitter::VisitUnaryLNot(const UnaryOperator *E) {
1262  // Compare operand to zero.
1263  Value *BoolVal = CGF.EvaluateExprAsBool(E->getSubExpr());
1264
1265  // Invert value.
1266  // TODO: Could dynamically modify easy computations here.  For example, if
1267  // the operand is an icmp ne, turn into icmp eq.
1268  BoolVal = Builder.CreateNot(BoolVal, "lnot");
1269
1270  // ZExt result to the expr type.
1271  return Builder.CreateZExt(BoolVal, ConvertType(E->getType()), "lnot.ext");
1272}
1273
1274Value *ScalarExprEmitter::VisitOffsetOfExpr(OffsetOfExpr *E) {
1275  // Try folding the offsetof to a constant.
1276  Expr::EvalResult EvalResult;
1277  if (E->Evaluate(EvalResult, CGF.getContext()))
1278    return llvm::ConstantInt::get(VMContext, EvalResult.Val.getInt());
1279
1280  // Loop over the components of the offsetof to compute the value.
1281  unsigned n = E->getNumComponents();
1282  const llvm::Type* ResultType = ConvertType(E->getType());
1283  llvm::Value* Result = llvm::Constant::getNullValue(ResultType);
1284  QualType CurrentType = E->getTypeSourceInfo()->getType();
1285  for (unsigned i = 0; i != n; ++i) {
1286    OffsetOfExpr::OffsetOfNode ON = E->getComponent(i);
1287    llvm::Value *Offset = 0;
1288    switch (ON.getKind()) {
1289    case OffsetOfExpr::OffsetOfNode::Array: {
1290      // Compute the index
1291      Expr *IdxExpr = E->getIndexExpr(ON.getArrayExprIndex());
1292      llvm::Value* Idx = CGF.EmitScalarExpr(IdxExpr);
1293      bool IdxSigned = IdxExpr->getType()->isSignedIntegerType();
1294      Idx = Builder.CreateIntCast(Idx, ResultType, IdxSigned, "conv");
1295
1296      // Save the element type
1297      CurrentType =
1298          CGF.getContext().getAsArrayType(CurrentType)->getElementType();
1299
1300      // Compute the element size
1301      llvm::Value* ElemSize = llvm::ConstantInt::get(ResultType,
1302          CGF.getContext().getTypeSizeInChars(CurrentType).getQuantity());
1303
1304      // Multiply out to compute the result
1305      Offset = Builder.CreateMul(Idx, ElemSize);
1306      break;
1307    }
1308
1309    case OffsetOfExpr::OffsetOfNode::Field: {
1310      FieldDecl *MemberDecl = ON.getField();
1311      RecordDecl *RD = CurrentType->getAs<RecordType>()->getDecl();
1312      const ASTRecordLayout &RL = CGF.getContext().getASTRecordLayout(RD);
1313
1314      // Compute the index of the field in its parent.
1315      unsigned i = 0;
1316      // FIXME: It would be nice if we didn't have to loop here!
1317      for (RecordDecl::field_iterator Field = RD->field_begin(),
1318                                      FieldEnd = RD->field_end();
1319           Field != FieldEnd; (void)++Field, ++i) {
1320        if (*Field == MemberDecl)
1321          break;
1322      }
1323      assert(i < RL.getFieldCount() && "offsetof field in wrong type");
1324
1325      // Compute the offset to the field
1326      int64_t OffsetInt = RL.getFieldOffset(i) /
1327                          CGF.getContext().getCharWidth();
1328      Offset = llvm::ConstantInt::get(ResultType, OffsetInt);
1329
1330      // Save the element type.
1331      CurrentType = MemberDecl->getType();
1332      break;
1333    }
1334
1335    case OffsetOfExpr::OffsetOfNode::Identifier:
1336      llvm_unreachable("dependent __builtin_offsetof");
1337
1338    case OffsetOfExpr::OffsetOfNode::Base: {
1339      if (ON.getBase()->isVirtual()) {
1340        CGF.ErrorUnsupported(E, "virtual base in offsetof");
1341        continue;
1342      }
1343
1344      RecordDecl *RD = CurrentType->getAs<RecordType>()->getDecl();
1345      const ASTRecordLayout &RL = CGF.getContext().getASTRecordLayout(RD);
1346
1347      // Save the element type.
1348      CurrentType = ON.getBase()->getType();
1349
1350      // Compute the offset to the base.
1351      const RecordType *BaseRT = CurrentType->getAs<RecordType>();
1352      CXXRecordDecl *BaseRD = cast<CXXRecordDecl>(BaseRT->getDecl());
1353      int64_t OffsetInt = RL.getBaseClassOffset(BaseRD) /
1354                          CGF.getContext().getCharWidth();
1355      Offset = llvm::ConstantInt::get(ResultType, OffsetInt);
1356      break;
1357    }
1358    }
1359    Result = Builder.CreateAdd(Result, Offset);
1360  }
1361  return Result;
1362}
1363
1364/// VisitSizeOfAlignOfExpr - Return the size or alignment of the type of
1365/// argument of the sizeof expression as an integer.
1366Value *
1367ScalarExprEmitter::VisitSizeOfAlignOfExpr(const SizeOfAlignOfExpr *E) {
1368  QualType TypeToSize = E->getTypeOfArgument();
1369  if (E->isSizeOf()) {
1370    if (const VariableArrayType *VAT =
1371          CGF.getContext().getAsVariableArrayType(TypeToSize)) {
1372      if (E->isArgumentType()) {
1373        // sizeof(type) - make sure to emit the VLA size.
1374        CGF.EmitVLASize(TypeToSize);
1375      } else {
1376        // C99 6.5.3.4p2: If the argument is an expression of type
1377        // VLA, it is evaluated.
1378        CGF.EmitAnyExpr(E->getArgumentExpr());
1379      }
1380
1381      return CGF.GetVLASize(VAT);
1382    }
1383  }
1384
1385  // If this isn't sizeof(vla), the result must be constant; use the constant
1386  // folding logic so we don't have to duplicate it here.
1387  Expr::EvalResult Result;
1388  E->Evaluate(Result, CGF.getContext());
1389  return llvm::ConstantInt::get(VMContext, Result.Val.getInt());
1390}
1391
1392Value *ScalarExprEmitter::VisitUnaryReal(const UnaryOperator *E) {
1393  Expr *Op = E->getSubExpr();
1394  if (Op->getType()->isAnyComplexType())
1395    return CGF.EmitComplexExpr(Op, false, true, false, true).first;
1396  return Visit(Op);
1397}
1398Value *ScalarExprEmitter::VisitUnaryImag(const UnaryOperator *E) {
1399  Expr *Op = E->getSubExpr();
1400  if (Op->getType()->isAnyComplexType())
1401    return CGF.EmitComplexExpr(Op, true, false, true, false).second;
1402
1403  // __imag on a scalar returns zero.  Emit the subexpr to ensure side
1404  // effects are evaluated, but not the actual value.
1405  if (E->isLvalue(CGF.getContext()) == Expr::LV_Valid)
1406    CGF.EmitLValue(Op);
1407  else
1408    CGF.EmitScalarExpr(Op, true);
1409  return llvm::Constant::getNullValue(ConvertType(E->getType()));
1410}
1411
1412Value *ScalarExprEmitter::VisitUnaryOffsetOf(const UnaryOperator *E) {
1413  Value* ResultAsPtr = EmitLValue(E->getSubExpr()).getAddress();
1414  const llvm::Type* ResultType = ConvertType(E->getType());
1415  return Builder.CreatePtrToInt(ResultAsPtr, ResultType, "offsetof");
1416}
1417
1418//===----------------------------------------------------------------------===//
1419//                           Binary Operators
1420//===----------------------------------------------------------------------===//
1421
1422BinOpInfo ScalarExprEmitter::EmitBinOps(const BinaryOperator *E) {
1423  TestAndClearIgnoreResultAssign();
1424  BinOpInfo Result;
1425  Result.LHS = Visit(E->getLHS());
1426  Result.RHS = Visit(E->getRHS());
1427  Result.Ty  = E->getType();
1428  Result.Opcode = E->getOpcode();
1429  Result.E = E;
1430  return Result;
1431}
1432
1433LValue ScalarExprEmitter::EmitCompoundAssignLValue(
1434                                              const CompoundAssignOperator *E,
1435                        Value *(ScalarExprEmitter::*Func)(const BinOpInfo &),
1436                                                   Value *&Result) {
1437  QualType LHSTy = E->getLHS()->getType();
1438  BinOpInfo OpInfo;
1439
1440  if (E->getComputationResultType()->isAnyComplexType()) {
1441    // This needs to go through the complex expression emitter, but it's a tad
1442    // complicated to do that... I'm leaving it out for now.  (Note that we do
1443    // actually need the imaginary part of the RHS for multiplication and
1444    // division.)
1445    CGF.ErrorUnsupported(E, "complex compound assignment");
1446    Result = llvm::UndefValue::get(CGF.ConvertType(E->getType()));
1447    return LValue();
1448  }
1449
1450  // Emit the RHS first.  __block variables need to have the rhs evaluated
1451  // first, plus this should improve codegen a little.
1452  OpInfo.RHS = Visit(E->getRHS());
1453  OpInfo.Ty = E->getComputationResultType();
1454  OpInfo.Opcode = E->getOpcode();
1455  OpInfo.E = E;
1456  // Load/convert the LHS.
1457  LValue LHSLV = EmitCheckedLValue(E->getLHS());
1458  OpInfo.LHS = EmitLoadOfLValue(LHSLV, LHSTy);
1459  OpInfo.LHS = EmitScalarConversion(OpInfo.LHS, LHSTy,
1460                                    E->getComputationLHSType());
1461
1462  // Expand the binary operator.
1463  Result = (this->*Func)(OpInfo);
1464
1465  // Convert the result back to the LHS type.
1466  Result = EmitScalarConversion(Result, E->getComputationResultType(), LHSTy);
1467
1468  // Store the result value into the LHS lvalue. Bit-fields are handled
1469  // specially because the result is altered by the store, i.e., [C99 6.5.16p1]
1470  // 'An assignment expression has the value of the left operand after the
1471  // assignment...'.
1472  if (LHSLV.isBitField())
1473    CGF.EmitStoreThroughBitfieldLValue(RValue::get(Result), LHSLV, LHSTy,
1474                                       &Result);
1475  else
1476    CGF.EmitStoreThroughLValue(RValue::get(Result), LHSLV, LHSTy);
1477
1478  return LHSLV;
1479}
1480
1481Value *ScalarExprEmitter::EmitCompoundAssign(const CompoundAssignOperator *E,
1482                      Value *(ScalarExprEmitter::*Func)(const BinOpInfo &)) {
1483  bool Ignore = TestAndClearIgnoreResultAssign();
1484  Value *RHS;
1485  LValue LHS = EmitCompoundAssignLValue(E, Func, RHS);
1486
1487  // If the result is clearly ignored, return now.
1488  if (Ignore)
1489    return 0;
1490
1491  // Objective-C property assignment never reloads the value following a store.
1492  if (LHS.isPropertyRef() || LHS.isKVCRef())
1493    return RHS;
1494
1495  // If the lvalue is non-volatile, return the computed value of the assignment.
1496  if (!LHS.isVolatileQualified())
1497    return RHS;
1498
1499  // Otherwise, reload the value.
1500  return EmitLoadOfLValue(LHS, E->getType());
1501}
1502
1503
1504Value *ScalarExprEmitter::EmitDiv(const BinOpInfo &Ops) {
1505  if (Ops.LHS->getType()->isFPOrFPVectorTy())
1506    return Builder.CreateFDiv(Ops.LHS, Ops.RHS, "div");
1507  else if (Ops.Ty->hasUnsignedIntegerRepresentation())
1508    return Builder.CreateUDiv(Ops.LHS, Ops.RHS, "div");
1509  else
1510    return Builder.CreateSDiv(Ops.LHS, Ops.RHS, "div");
1511}
1512
1513Value *ScalarExprEmitter::EmitRem(const BinOpInfo &Ops) {
1514  // Rem in C can't be a floating point type: C99 6.5.5p2.
1515  if (Ops.Ty->isUnsignedIntegerType())
1516    return Builder.CreateURem(Ops.LHS, Ops.RHS, "rem");
1517  else
1518    return Builder.CreateSRem(Ops.LHS, Ops.RHS, "rem");
1519}
1520
1521Value *ScalarExprEmitter::EmitOverflowCheckedBinOp(const BinOpInfo &Ops) {
1522  unsigned IID;
1523  unsigned OpID = 0;
1524
1525  switch (Ops.Opcode) {
1526  case BinaryOperator::Add:
1527  case BinaryOperator::AddAssign:
1528    OpID = 1;
1529    IID = llvm::Intrinsic::sadd_with_overflow;
1530    break;
1531  case BinaryOperator::Sub:
1532  case BinaryOperator::SubAssign:
1533    OpID = 2;
1534    IID = llvm::Intrinsic::ssub_with_overflow;
1535    break;
1536  case BinaryOperator::Mul:
1537  case BinaryOperator::MulAssign:
1538    OpID = 3;
1539    IID = llvm::Intrinsic::smul_with_overflow;
1540    break;
1541  default:
1542    assert(false && "Unsupported operation for overflow detection");
1543    IID = 0;
1544  }
1545  OpID <<= 1;
1546  OpID |= 1;
1547
1548  const llvm::Type *opTy = CGF.CGM.getTypes().ConvertType(Ops.Ty);
1549
1550  llvm::Function *intrinsic = CGF.CGM.getIntrinsic(IID, &opTy, 1);
1551
1552  Value *resultAndOverflow = Builder.CreateCall2(intrinsic, Ops.LHS, Ops.RHS);
1553  Value *result = Builder.CreateExtractValue(resultAndOverflow, 0);
1554  Value *overflow = Builder.CreateExtractValue(resultAndOverflow, 1);
1555
1556  // Branch in case of overflow.
1557  llvm::BasicBlock *overflowBB = CGF.createBasicBlock("overflow", CGF.CurFn);
1558  llvm::BasicBlock *continueBB = CGF.createBasicBlock("nooverflow", CGF.CurFn);
1559
1560  Builder.CreateCondBr(overflow, overflowBB, continueBB);
1561
1562  // Handle overflow with llvm.trap.
1563  // TODO: it would be better to generate one of these blocks per function.
1564  Builder.SetInsertPoint(overflowBB);
1565  llvm::Function *Trap = CGF.CGM.getIntrinsic(llvm::Intrinsic::trap);
1566  Builder.CreateCall(Trap);
1567  Builder.CreateUnreachable();
1568
1569  // Continue on.
1570  Builder.SetInsertPoint(continueBB);
1571  return result;
1572}
1573
1574Value *ScalarExprEmitter::EmitAdd(const BinOpInfo &Ops) {
1575  if (!Ops.Ty->isAnyPointerType()) {
1576    if (Ops.Ty->hasSignedIntegerRepresentation()) {
1577      switch (CGF.getContext().getLangOptions().getSignedOverflowBehavior()) {
1578      case LangOptions::SOB_Undefined:
1579        return Builder.CreateNSWAdd(Ops.LHS, Ops.RHS, "add");
1580      case LangOptions::SOB_Defined:
1581        return Builder.CreateAdd(Ops.LHS, Ops.RHS, "add");
1582      case LangOptions::SOB_Trapping:
1583        return EmitOverflowCheckedBinOp(Ops);
1584      }
1585    }
1586
1587    if (Ops.LHS->getType()->isFPOrFPVectorTy())
1588      return Builder.CreateFAdd(Ops.LHS, Ops.RHS, "add");
1589
1590    return Builder.CreateAdd(Ops.LHS, Ops.RHS, "add");
1591  }
1592
1593  // Must have binary (not unary) expr here.  Unary pointer decrement doesn't
1594  // use this path.
1595  const BinaryOperator *BinOp = cast<BinaryOperator>(Ops.E);
1596
1597  if (Ops.Ty->isPointerType() &&
1598      Ops.Ty->getAs<PointerType>()->isVariableArrayType()) {
1599    // The amount of the addition needs to account for the VLA size
1600    CGF.ErrorUnsupported(BinOp, "VLA pointer addition");
1601  }
1602
1603  Value *Ptr, *Idx;
1604  Expr *IdxExp;
1605  const PointerType *PT = BinOp->getLHS()->getType()->getAs<PointerType>();
1606  const ObjCObjectPointerType *OPT =
1607    BinOp->getLHS()->getType()->getAs<ObjCObjectPointerType>();
1608  if (PT || OPT) {
1609    Ptr = Ops.LHS;
1610    Idx = Ops.RHS;
1611    IdxExp = BinOp->getRHS();
1612  } else {  // int + pointer
1613    PT = BinOp->getRHS()->getType()->getAs<PointerType>();
1614    OPT = BinOp->getRHS()->getType()->getAs<ObjCObjectPointerType>();
1615    assert((PT || OPT) && "Invalid add expr");
1616    Ptr = Ops.RHS;
1617    Idx = Ops.LHS;
1618    IdxExp = BinOp->getLHS();
1619  }
1620
1621  unsigned Width = cast<llvm::IntegerType>(Idx->getType())->getBitWidth();
1622  if (Width < CGF.LLVMPointerWidth) {
1623    // Zero or sign extend the pointer value based on whether the index is
1624    // signed or not.
1625    const llvm::Type *IdxType = CGF.IntPtrTy;
1626    if (IdxExp->getType()->isSignedIntegerType())
1627      Idx = Builder.CreateSExt(Idx, IdxType, "idx.ext");
1628    else
1629      Idx = Builder.CreateZExt(Idx, IdxType, "idx.ext");
1630  }
1631  const QualType ElementType = PT ? PT->getPointeeType() : OPT->getPointeeType();
1632  // Handle interface types, which are not represented with a concrete type.
1633  if (const ObjCObjectType *OIT = ElementType->getAs<ObjCObjectType>()) {
1634    llvm::Value *InterfaceSize =
1635      llvm::ConstantInt::get(Idx->getType(),
1636          CGF.getContext().getTypeSizeInChars(OIT).getQuantity());
1637    Idx = Builder.CreateMul(Idx, InterfaceSize);
1638    const llvm::Type *i8Ty = llvm::Type::getInt8PtrTy(VMContext);
1639    Value *Casted = Builder.CreateBitCast(Ptr, i8Ty);
1640    Value *Res = Builder.CreateGEP(Casted, Idx, "add.ptr");
1641    return Builder.CreateBitCast(Res, Ptr->getType());
1642  }
1643
1644  // Explicitly handle GNU void* and function pointer arithmetic extensions. The
1645  // GNU void* casts amount to no-ops since our void* type is i8*, but this is
1646  // future proof.
1647  if (ElementType->isVoidType() || ElementType->isFunctionType()) {
1648    const llvm::Type *i8Ty = llvm::Type::getInt8PtrTy(VMContext);
1649    Value *Casted = Builder.CreateBitCast(Ptr, i8Ty);
1650    Value *Res = Builder.CreateGEP(Casted, Idx, "add.ptr");
1651    return Builder.CreateBitCast(Res, Ptr->getType());
1652  }
1653
1654  return Builder.CreateInBoundsGEP(Ptr, Idx, "add.ptr");
1655}
1656
1657Value *ScalarExprEmitter::EmitSub(const BinOpInfo &Ops) {
1658  if (!isa<llvm::PointerType>(Ops.LHS->getType())) {
1659    if (Ops.Ty->hasSignedIntegerRepresentation()) {
1660      switch (CGF.getContext().getLangOptions().getSignedOverflowBehavior()) {
1661      case LangOptions::SOB_Undefined:
1662        return Builder.CreateNSWSub(Ops.LHS, Ops.RHS, "sub");
1663      case LangOptions::SOB_Defined:
1664        return Builder.CreateSub(Ops.LHS, Ops.RHS, "sub");
1665      case LangOptions::SOB_Trapping:
1666        return EmitOverflowCheckedBinOp(Ops);
1667      }
1668    }
1669
1670    if (Ops.LHS->getType()->isFPOrFPVectorTy())
1671      return Builder.CreateFSub(Ops.LHS, Ops.RHS, "sub");
1672
1673    return Builder.CreateSub(Ops.LHS, Ops.RHS, "sub");
1674  }
1675
1676  // Must have binary (not unary) expr here.  Unary pointer increment doesn't
1677  // use this path.
1678  const BinaryOperator *BinOp = cast<BinaryOperator>(Ops.E);
1679
1680  if (BinOp->getLHS()->getType()->isPointerType() &&
1681      BinOp->getLHS()->getType()->getAs<PointerType>()->isVariableArrayType()) {
1682    // The amount of the addition needs to account for the VLA size for
1683    // ptr-int
1684    // The amount of the division needs to account for the VLA size for
1685    // ptr-ptr.
1686    CGF.ErrorUnsupported(BinOp, "VLA pointer subtraction");
1687  }
1688
1689  const QualType LHSType = BinOp->getLHS()->getType();
1690  const QualType LHSElementType = LHSType->getPointeeType();
1691  if (!isa<llvm::PointerType>(Ops.RHS->getType())) {
1692    // pointer - int
1693    Value *Idx = Ops.RHS;
1694    unsigned Width = cast<llvm::IntegerType>(Idx->getType())->getBitWidth();
1695    if (Width < CGF.LLVMPointerWidth) {
1696      // Zero or sign extend the pointer value based on whether the index is
1697      // signed or not.
1698      const llvm::Type *IdxType = CGF.IntPtrTy;
1699      if (BinOp->getRHS()->getType()->isSignedIntegerType())
1700        Idx = Builder.CreateSExt(Idx, IdxType, "idx.ext");
1701      else
1702        Idx = Builder.CreateZExt(Idx, IdxType, "idx.ext");
1703    }
1704    Idx = Builder.CreateNeg(Idx, "sub.ptr.neg");
1705
1706    // Handle interface types, which are not represented with a concrete type.
1707    if (const ObjCObjectType *OIT = LHSElementType->getAs<ObjCObjectType>()) {
1708      llvm::Value *InterfaceSize =
1709        llvm::ConstantInt::get(Idx->getType(),
1710                               CGF.getContext().
1711                                 getTypeSizeInChars(OIT).getQuantity());
1712      Idx = Builder.CreateMul(Idx, InterfaceSize);
1713      const llvm::Type *i8Ty = llvm::Type::getInt8PtrTy(VMContext);
1714      Value *LHSCasted = Builder.CreateBitCast(Ops.LHS, i8Ty);
1715      Value *Res = Builder.CreateGEP(LHSCasted, Idx, "add.ptr");
1716      return Builder.CreateBitCast(Res, Ops.LHS->getType());
1717    }
1718
1719    // Explicitly handle GNU void* and function pointer arithmetic
1720    // extensions. The GNU void* casts amount to no-ops since our void* type is
1721    // i8*, but this is future proof.
1722    if (LHSElementType->isVoidType() || LHSElementType->isFunctionType()) {
1723      const llvm::Type *i8Ty = llvm::Type::getInt8PtrTy(VMContext);
1724      Value *LHSCasted = Builder.CreateBitCast(Ops.LHS, i8Ty);
1725      Value *Res = Builder.CreateGEP(LHSCasted, Idx, "sub.ptr");
1726      return Builder.CreateBitCast(Res, Ops.LHS->getType());
1727    }
1728
1729    return Builder.CreateInBoundsGEP(Ops.LHS, Idx, "sub.ptr");
1730  } else {
1731    // pointer - pointer
1732    Value *LHS = Ops.LHS;
1733    Value *RHS = Ops.RHS;
1734
1735    CharUnits ElementSize;
1736
1737    // Handle GCC extension for pointer arithmetic on void* and function pointer
1738    // types.
1739    if (LHSElementType->isVoidType() || LHSElementType->isFunctionType()) {
1740      ElementSize = CharUnits::One();
1741    } else {
1742      ElementSize = CGF.getContext().getTypeSizeInChars(LHSElementType);
1743    }
1744
1745    const llvm::Type *ResultType = ConvertType(Ops.Ty);
1746    LHS = Builder.CreatePtrToInt(LHS, ResultType, "sub.ptr.lhs.cast");
1747    RHS = Builder.CreatePtrToInt(RHS, ResultType, "sub.ptr.rhs.cast");
1748    Value *BytesBetween = Builder.CreateSub(LHS, RHS, "sub.ptr.sub");
1749
1750    // Optimize out the shift for element size of 1.
1751    if (ElementSize.isOne())
1752      return BytesBetween;
1753
1754    // Otherwise, do a full sdiv. This uses the "exact" form of sdiv, since
1755    // pointer difference in C is only defined in the case where both operands
1756    // are pointing to elements of an array.
1757    Value *BytesPerElt =
1758        llvm::ConstantInt::get(ResultType, ElementSize.getQuantity());
1759    return Builder.CreateExactSDiv(BytesBetween, BytesPerElt, "sub.ptr.div");
1760  }
1761}
1762
1763Value *ScalarExprEmitter::EmitShl(const BinOpInfo &Ops) {
1764  // LLVM requires the LHS and RHS to be the same type: promote or truncate the
1765  // RHS to the same size as the LHS.
1766  Value *RHS = Ops.RHS;
1767  if (Ops.LHS->getType() != RHS->getType())
1768    RHS = Builder.CreateIntCast(RHS, Ops.LHS->getType(), false, "sh_prom");
1769
1770  if (CGF.CatchUndefined
1771      && isa<llvm::IntegerType>(Ops.LHS->getType())) {
1772    unsigned Width = cast<llvm::IntegerType>(Ops.LHS->getType())->getBitWidth();
1773    llvm::BasicBlock *Cont = CGF.createBasicBlock("cont");
1774    CGF.Builder.CreateCondBr(Builder.CreateICmpULT(RHS,
1775                                 llvm::ConstantInt::get(RHS->getType(), Width)),
1776                             Cont, CGF.getTrapBB());
1777    CGF.EmitBlock(Cont);
1778  }
1779
1780  return Builder.CreateShl(Ops.LHS, RHS, "shl");
1781}
1782
1783Value *ScalarExprEmitter::EmitShr(const BinOpInfo &Ops) {
1784  // LLVM requires the LHS and RHS to be the same type: promote or truncate the
1785  // RHS to the same size as the LHS.
1786  Value *RHS = Ops.RHS;
1787  if (Ops.LHS->getType() != RHS->getType())
1788    RHS = Builder.CreateIntCast(RHS, Ops.LHS->getType(), false, "sh_prom");
1789
1790  if (CGF.CatchUndefined
1791      && isa<llvm::IntegerType>(Ops.LHS->getType())) {
1792    unsigned Width = cast<llvm::IntegerType>(Ops.LHS->getType())->getBitWidth();
1793    llvm::BasicBlock *Cont = CGF.createBasicBlock("cont");
1794    CGF.Builder.CreateCondBr(Builder.CreateICmpULT(RHS,
1795                                 llvm::ConstantInt::get(RHS->getType(), Width)),
1796                             Cont, CGF.getTrapBB());
1797    CGF.EmitBlock(Cont);
1798  }
1799
1800  if (Ops.Ty->hasUnsignedIntegerRepresentation())
1801    return Builder.CreateLShr(Ops.LHS, RHS, "shr");
1802  return Builder.CreateAShr(Ops.LHS, RHS, "shr");
1803}
1804
1805Value *ScalarExprEmitter::EmitCompare(const BinaryOperator *E,unsigned UICmpOpc,
1806                                      unsigned SICmpOpc, unsigned FCmpOpc) {
1807  TestAndClearIgnoreResultAssign();
1808  Value *Result;
1809  QualType LHSTy = E->getLHS()->getType();
1810  if (LHSTy->isMemberFunctionPointerType()) {
1811    Value *LHSPtr = CGF.EmitAnyExprToTemp(E->getLHS()).getAggregateAddr();
1812    Value *RHSPtr = CGF.EmitAnyExprToTemp(E->getRHS()).getAggregateAddr();
1813    llvm::Value *LHSFunc = Builder.CreateStructGEP(LHSPtr, 0);
1814    LHSFunc = Builder.CreateLoad(LHSFunc);
1815    llvm::Value *RHSFunc = Builder.CreateStructGEP(RHSPtr, 0);
1816    RHSFunc = Builder.CreateLoad(RHSFunc);
1817    Value *ResultF = Builder.CreateICmp((llvm::ICmpInst::Predicate)UICmpOpc,
1818                                        LHSFunc, RHSFunc, "cmp.func");
1819    Value *NullPtr = llvm::Constant::getNullValue(LHSFunc->getType());
1820    Value *ResultNull = Builder.CreateICmp((llvm::ICmpInst::Predicate)UICmpOpc,
1821                                           LHSFunc, NullPtr, "cmp.null");
1822    llvm::Value *LHSAdj = Builder.CreateStructGEP(LHSPtr, 1);
1823    LHSAdj = Builder.CreateLoad(LHSAdj);
1824    llvm::Value *RHSAdj = Builder.CreateStructGEP(RHSPtr, 1);
1825    RHSAdj = Builder.CreateLoad(RHSAdj);
1826    Value *ResultA = Builder.CreateICmp((llvm::ICmpInst::Predicate)UICmpOpc,
1827                                        LHSAdj, RHSAdj, "cmp.adj");
1828    if (E->getOpcode() == BinaryOperator::EQ) {
1829      Result = Builder.CreateOr(ResultNull, ResultA, "or.na");
1830      Result = Builder.CreateAnd(Result, ResultF, "and.f");
1831    } else {
1832      assert(E->getOpcode() == BinaryOperator::NE &&
1833             "Member pointer comparison other than == or != ?");
1834      Result = Builder.CreateAnd(ResultNull, ResultA, "and.na");
1835      Result = Builder.CreateOr(Result, ResultF, "or.f");
1836    }
1837  } else if (!LHSTy->isAnyComplexType()) {
1838    Value *LHS = Visit(E->getLHS());
1839    Value *RHS = Visit(E->getRHS());
1840
1841    if (LHS->getType()->isFPOrFPVectorTy()) {
1842      Result = Builder.CreateFCmp((llvm::CmpInst::Predicate)FCmpOpc,
1843                                  LHS, RHS, "cmp");
1844    } else if (LHSTy->hasSignedIntegerRepresentation()) {
1845      Result = Builder.CreateICmp((llvm::ICmpInst::Predicate)SICmpOpc,
1846                                  LHS, RHS, "cmp");
1847    } else {
1848      // Unsigned integers and pointers.
1849      Result = Builder.CreateICmp((llvm::ICmpInst::Predicate)UICmpOpc,
1850                                  LHS, RHS, "cmp");
1851    }
1852
1853    // If this is a vector comparison, sign extend the result to the appropriate
1854    // vector integer type and return it (don't convert to bool).
1855    if (LHSTy->isVectorType())
1856      return Builder.CreateSExt(Result, ConvertType(E->getType()), "sext");
1857
1858  } else {
1859    // Complex Comparison: can only be an equality comparison.
1860    CodeGenFunction::ComplexPairTy LHS = CGF.EmitComplexExpr(E->getLHS());
1861    CodeGenFunction::ComplexPairTy RHS = CGF.EmitComplexExpr(E->getRHS());
1862
1863    QualType CETy = LHSTy->getAs<ComplexType>()->getElementType();
1864
1865    Value *ResultR, *ResultI;
1866    if (CETy->isRealFloatingType()) {
1867      ResultR = Builder.CreateFCmp((llvm::FCmpInst::Predicate)FCmpOpc,
1868                                   LHS.first, RHS.first, "cmp.r");
1869      ResultI = Builder.CreateFCmp((llvm::FCmpInst::Predicate)FCmpOpc,
1870                                   LHS.second, RHS.second, "cmp.i");
1871    } else {
1872      // Complex comparisons can only be equality comparisons.  As such, signed
1873      // and unsigned opcodes are the same.
1874      ResultR = Builder.CreateICmp((llvm::ICmpInst::Predicate)UICmpOpc,
1875                                   LHS.first, RHS.first, "cmp.r");
1876      ResultI = Builder.CreateICmp((llvm::ICmpInst::Predicate)UICmpOpc,
1877                                   LHS.second, RHS.second, "cmp.i");
1878    }
1879
1880    if (E->getOpcode() == BinaryOperator::EQ) {
1881      Result = Builder.CreateAnd(ResultR, ResultI, "and.ri");
1882    } else {
1883      assert(E->getOpcode() == BinaryOperator::NE &&
1884             "Complex comparison other than == or != ?");
1885      Result = Builder.CreateOr(ResultR, ResultI, "or.ri");
1886    }
1887  }
1888
1889  return EmitScalarConversion(Result, CGF.getContext().BoolTy, E->getType());
1890}
1891
1892Value *ScalarExprEmitter::VisitBinAssign(const BinaryOperator *E) {
1893  bool Ignore = TestAndClearIgnoreResultAssign();
1894
1895  // __block variables need to have the rhs evaluated first, plus this should
1896  // improve codegen just a little.
1897  Value *RHS = Visit(E->getRHS());
1898  LValue LHS = EmitCheckedLValue(E->getLHS());
1899
1900  // Store the value into the LHS.  Bit-fields are handled specially
1901  // because the result is altered by the store, i.e., [C99 6.5.16p1]
1902  // 'An assignment expression has the value of the left operand after
1903  // the assignment...'.
1904  if (LHS.isBitField())
1905    CGF.EmitStoreThroughBitfieldLValue(RValue::get(RHS), LHS, E->getType(),
1906                                       &RHS);
1907  else
1908    CGF.EmitStoreThroughLValue(RValue::get(RHS), LHS, E->getType());
1909
1910  // If the result is clearly ignored, return now.
1911  if (Ignore)
1912    return 0;
1913
1914  // Objective-C property assignment never reloads the value following a store.
1915  if (LHS.isPropertyRef() || LHS.isKVCRef())
1916    return RHS;
1917
1918  // If the lvalue is non-volatile, return the computed value of the assignment.
1919  if (!LHS.isVolatileQualified())
1920    return RHS;
1921
1922  // Otherwise, reload the value.
1923  return EmitLoadOfLValue(LHS, E->getType());
1924}
1925
1926Value *ScalarExprEmitter::VisitBinLAnd(const BinaryOperator *E) {
1927  const llvm::Type *ResTy = ConvertType(E->getType());
1928
1929  // If we have 0 && RHS, see if we can elide RHS, if so, just return 0.
1930  // If we have 1 && X, just emit X without inserting the control flow.
1931  if (int Cond = CGF.ConstantFoldsToSimpleInteger(E->getLHS())) {
1932    if (Cond == 1) { // If we have 1 && X, just emit X.
1933      Value *RHSCond = CGF.EvaluateExprAsBool(E->getRHS());
1934      // ZExt result to int or bool.
1935      return Builder.CreateZExtOrBitCast(RHSCond, ResTy, "land.ext");
1936    }
1937
1938    // 0 && RHS: If it is safe, just elide the RHS, and return 0/false.
1939    if (!CGF.ContainsLabel(E->getRHS()))
1940      return llvm::Constant::getNullValue(ResTy);
1941  }
1942
1943  llvm::BasicBlock *ContBlock = CGF.createBasicBlock("land.end");
1944  llvm::BasicBlock *RHSBlock  = CGF.createBasicBlock("land.rhs");
1945
1946  // Branch on the LHS first.  If it is false, go to the failure (cont) block.
1947  CGF.EmitBranchOnBoolExpr(E->getLHS(), RHSBlock, ContBlock);
1948
1949  // Any edges into the ContBlock are now from an (indeterminate number of)
1950  // edges from this first condition.  All of these values will be false.  Start
1951  // setting up the PHI node in the Cont Block for this.
1952  llvm::PHINode *PN = llvm::PHINode::Create(llvm::Type::getInt1Ty(VMContext),
1953                                            "", ContBlock);
1954  PN->reserveOperandSpace(2);  // Normal case, two inputs.
1955  for (llvm::pred_iterator PI = pred_begin(ContBlock), PE = pred_end(ContBlock);
1956       PI != PE; ++PI)
1957    PN->addIncoming(llvm::ConstantInt::getFalse(VMContext), *PI);
1958
1959  CGF.BeginConditionalBranch();
1960  CGF.EmitBlock(RHSBlock);
1961  Value *RHSCond = CGF.EvaluateExprAsBool(E->getRHS());
1962  CGF.EndConditionalBranch();
1963
1964  // Reaquire the RHS block, as there may be subblocks inserted.
1965  RHSBlock = Builder.GetInsertBlock();
1966
1967  // Emit an unconditional branch from this block to ContBlock.  Insert an entry
1968  // into the phi node for the edge with the value of RHSCond.
1969  CGF.EmitBlock(ContBlock);
1970  PN->addIncoming(RHSCond, RHSBlock);
1971
1972  // ZExt result to int.
1973  return Builder.CreateZExtOrBitCast(PN, ResTy, "land.ext");
1974}
1975
1976Value *ScalarExprEmitter::VisitBinLOr(const BinaryOperator *E) {
1977  const llvm::Type *ResTy = ConvertType(E->getType());
1978
1979  // If we have 1 || RHS, see if we can elide RHS, if so, just return 1.
1980  // If we have 0 || X, just emit X without inserting the control flow.
1981  if (int Cond = CGF.ConstantFoldsToSimpleInteger(E->getLHS())) {
1982    if (Cond == -1) { // If we have 0 || X, just emit X.
1983      Value *RHSCond = CGF.EvaluateExprAsBool(E->getRHS());
1984      // ZExt result to int or bool.
1985      return Builder.CreateZExtOrBitCast(RHSCond, ResTy, "lor.ext");
1986    }
1987
1988    // 1 || RHS: If it is safe, just elide the RHS, and return 1/true.
1989    if (!CGF.ContainsLabel(E->getRHS()))
1990      return llvm::ConstantInt::get(ResTy, 1);
1991  }
1992
1993  llvm::BasicBlock *ContBlock = CGF.createBasicBlock("lor.end");
1994  llvm::BasicBlock *RHSBlock = CGF.createBasicBlock("lor.rhs");
1995
1996  // Branch on the LHS first.  If it is true, go to the success (cont) block.
1997  CGF.EmitBranchOnBoolExpr(E->getLHS(), ContBlock, RHSBlock);
1998
1999  // Any edges into the ContBlock are now from an (indeterminate number of)
2000  // edges from this first condition.  All of these values will be true.  Start
2001  // setting up the PHI node in the Cont Block for this.
2002  llvm::PHINode *PN = llvm::PHINode::Create(llvm::Type::getInt1Ty(VMContext),
2003                                            "", ContBlock);
2004  PN->reserveOperandSpace(2);  // Normal case, two inputs.
2005  for (llvm::pred_iterator PI = pred_begin(ContBlock), PE = pred_end(ContBlock);
2006       PI != PE; ++PI)
2007    PN->addIncoming(llvm::ConstantInt::getTrue(VMContext), *PI);
2008
2009  CGF.BeginConditionalBranch();
2010
2011  // Emit the RHS condition as a bool value.
2012  CGF.EmitBlock(RHSBlock);
2013  Value *RHSCond = CGF.EvaluateExprAsBool(E->getRHS());
2014
2015  CGF.EndConditionalBranch();
2016
2017  // Reaquire the RHS block, as there may be subblocks inserted.
2018  RHSBlock = Builder.GetInsertBlock();
2019
2020  // Emit an unconditional branch from this block to ContBlock.  Insert an entry
2021  // into the phi node for the edge with the value of RHSCond.
2022  CGF.EmitBlock(ContBlock);
2023  PN->addIncoming(RHSCond, RHSBlock);
2024
2025  // ZExt result to int.
2026  return Builder.CreateZExtOrBitCast(PN, ResTy, "lor.ext");
2027}
2028
2029Value *ScalarExprEmitter::VisitBinComma(const BinaryOperator *E) {
2030  CGF.EmitStmt(E->getLHS());
2031  CGF.EnsureInsertPoint();
2032  return Visit(E->getRHS());
2033}
2034
2035//===----------------------------------------------------------------------===//
2036//                             Other Operators
2037//===----------------------------------------------------------------------===//
2038
2039/// isCheapEnoughToEvaluateUnconditionally - Return true if the specified
2040/// expression is cheap enough and side-effect-free enough to evaluate
2041/// unconditionally instead of conditionally.  This is used to convert control
2042/// flow into selects in some cases.
2043static bool isCheapEnoughToEvaluateUnconditionally(const Expr *E,
2044                                                   CodeGenFunction &CGF) {
2045  if (const ParenExpr *PE = dyn_cast<ParenExpr>(E))
2046    return isCheapEnoughToEvaluateUnconditionally(PE->getSubExpr(), CGF);
2047
2048  // TODO: Allow anything we can constant fold to an integer or fp constant.
2049  if (isa<IntegerLiteral>(E) || isa<CharacterLiteral>(E) ||
2050      isa<FloatingLiteral>(E))
2051    return true;
2052
2053  // Non-volatile automatic variables too, to get "cond ? X : Y" where
2054  // X and Y are local variables.
2055  if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
2056    if (const VarDecl *VD = dyn_cast<VarDecl>(DRE->getDecl()))
2057      if (VD->hasLocalStorage() && !(CGF.getContext()
2058                                     .getCanonicalType(VD->getType())
2059                                     .isVolatileQualified()))
2060        return true;
2061
2062  return false;
2063}
2064
2065
2066Value *ScalarExprEmitter::
2067VisitConditionalOperator(const ConditionalOperator *E) {
2068  TestAndClearIgnoreResultAssign();
2069  // If the condition constant folds and can be elided, try to avoid emitting
2070  // the condition and the dead arm.
2071  if (int Cond = CGF.ConstantFoldsToSimpleInteger(E->getCond())){
2072    Expr *Live = E->getLHS(), *Dead = E->getRHS();
2073    if (Cond == -1)
2074      std::swap(Live, Dead);
2075
2076    // If the dead side doesn't have labels we need, and if the Live side isn't
2077    // the gnu missing ?: extension (which we could handle, but don't bother
2078    // to), just emit the Live part.
2079    if ((!Dead || !CGF.ContainsLabel(Dead)) &&  // No labels in dead part
2080        Live)                                   // Live part isn't missing.
2081      return Visit(Live);
2082  }
2083
2084
2085  // If this is a really simple expression (like x ? 4 : 5), emit this as a
2086  // select instead of as control flow.  We can only do this if it is cheap and
2087  // safe to evaluate the LHS and RHS unconditionally.
2088  if (E->getLHS() && isCheapEnoughToEvaluateUnconditionally(E->getLHS(),
2089                                                            CGF) &&
2090      isCheapEnoughToEvaluateUnconditionally(E->getRHS(), CGF)) {
2091    llvm::Value *CondV = CGF.EvaluateExprAsBool(E->getCond());
2092    llvm::Value *LHS = Visit(E->getLHS());
2093    llvm::Value *RHS = Visit(E->getRHS());
2094    return Builder.CreateSelect(CondV, LHS, RHS, "cond");
2095  }
2096
2097
2098  llvm::BasicBlock *LHSBlock = CGF.createBasicBlock("cond.true");
2099  llvm::BasicBlock *RHSBlock = CGF.createBasicBlock("cond.false");
2100  llvm::BasicBlock *ContBlock = CGF.createBasicBlock("cond.end");
2101  Value *CondVal = 0;
2102
2103  // If we don't have the GNU missing condition extension, emit a branch on bool
2104  // the normal way.
2105  if (E->getLHS()) {
2106    // Otherwise, just use EmitBranchOnBoolExpr to get small and simple code for
2107    // the branch on bool.
2108    CGF.EmitBranchOnBoolExpr(E->getCond(), LHSBlock, RHSBlock);
2109  } else {
2110    // Otherwise, for the ?: extension, evaluate the conditional and then
2111    // convert it to bool the hard way.  We do this explicitly because we need
2112    // the unconverted value for the missing middle value of the ?:.
2113    CondVal = CGF.EmitScalarExpr(E->getCond());
2114
2115    // In some cases, EmitScalarConversion will delete the "CondVal" expression
2116    // if there are no extra uses (an optimization).  Inhibit this by making an
2117    // extra dead use, because we're going to add a use of CondVal later.  We
2118    // don't use the builder for this, because we don't want it to get optimized
2119    // away.  This leaves dead code, but the ?: extension isn't common.
2120    new llvm::BitCastInst(CondVal, CondVal->getType(), "dummy?:holder",
2121                          Builder.GetInsertBlock());
2122
2123    Value *CondBoolVal =
2124      CGF.EmitScalarConversion(CondVal, E->getCond()->getType(),
2125                               CGF.getContext().BoolTy);
2126    Builder.CreateCondBr(CondBoolVal, LHSBlock, RHSBlock);
2127  }
2128
2129  CGF.BeginConditionalBranch();
2130  CGF.EmitBlock(LHSBlock);
2131
2132  // Handle the GNU extension for missing LHS.
2133  Value *LHS;
2134  if (E->getLHS())
2135    LHS = Visit(E->getLHS());
2136  else    // Perform promotions, to handle cases like "short ?: int"
2137    LHS = EmitScalarConversion(CondVal, E->getCond()->getType(), E->getType());
2138
2139  CGF.EndConditionalBranch();
2140  LHSBlock = Builder.GetInsertBlock();
2141  CGF.EmitBranch(ContBlock);
2142
2143  CGF.BeginConditionalBranch();
2144  CGF.EmitBlock(RHSBlock);
2145
2146  Value *RHS = Visit(E->getRHS());
2147  CGF.EndConditionalBranch();
2148  RHSBlock = Builder.GetInsertBlock();
2149  CGF.EmitBranch(ContBlock);
2150
2151  CGF.EmitBlock(ContBlock);
2152
2153  // If the LHS or RHS is a throw expression, it will be legitimately null.
2154  if (!LHS)
2155    return RHS;
2156  if (!RHS)
2157    return LHS;
2158
2159  // Create a PHI node for the real part.
2160  llvm::PHINode *PN = Builder.CreatePHI(LHS->getType(), "cond");
2161  PN->reserveOperandSpace(2);
2162  PN->addIncoming(LHS, LHSBlock);
2163  PN->addIncoming(RHS, RHSBlock);
2164  return PN;
2165}
2166
2167Value *ScalarExprEmitter::VisitChooseExpr(ChooseExpr *E) {
2168  return Visit(E->getChosenSubExpr(CGF.getContext()));
2169}
2170
2171Value *ScalarExprEmitter::VisitVAArgExpr(VAArgExpr *VE) {
2172  llvm::Value *ArgValue = CGF.EmitVAListRef(VE->getSubExpr());
2173  llvm::Value *ArgPtr = CGF.EmitVAArg(ArgValue, VE->getType());
2174
2175  // If EmitVAArg fails, we fall back to the LLVM instruction.
2176  if (!ArgPtr)
2177    return Builder.CreateVAArg(ArgValue, ConvertType(VE->getType()));
2178
2179  // FIXME Volatility.
2180  return Builder.CreateLoad(ArgPtr);
2181}
2182
2183Value *ScalarExprEmitter::VisitBlockExpr(const BlockExpr *BE) {
2184  return CGF.BuildBlockLiteralTmp(BE);
2185}
2186
2187//===----------------------------------------------------------------------===//
2188//                         Entry Point into this File
2189//===----------------------------------------------------------------------===//
2190
2191/// EmitScalarExpr - Emit the computation of the specified expression of scalar
2192/// type, ignoring the result.
2193Value *CodeGenFunction::EmitScalarExpr(const Expr *E, bool IgnoreResultAssign) {
2194  assert(E && !hasAggregateLLVMType(E->getType()) &&
2195         "Invalid scalar expression to emit");
2196
2197  return ScalarExprEmitter(*this, IgnoreResultAssign)
2198    .Visit(const_cast<Expr*>(E));
2199}
2200
2201/// EmitScalarConversion - Emit a conversion from the specified type to the
2202/// specified destination type, both of which are LLVM scalar types.
2203Value *CodeGenFunction::EmitScalarConversion(Value *Src, QualType SrcTy,
2204                                             QualType DstTy) {
2205  assert(!hasAggregateLLVMType(SrcTy) && !hasAggregateLLVMType(DstTy) &&
2206         "Invalid scalar expression to emit");
2207  return ScalarExprEmitter(*this).EmitScalarConversion(Src, SrcTy, DstTy);
2208}
2209
2210/// EmitComplexToScalarConversion - Emit a conversion from the specified complex
2211/// type to the specified destination type, where the destination type is an
2212/// LLVM scalar type.
2213Value *CodeGenFunction::EmitComplexToScalarConversion(ComplexPairTy Src,
2214                                                      QualType SrcTy,
2215                                                      QualType DstTy) {
2216  assert(SrcTy->isAnyComplexType() && !hasAggregateLLVMType(DstTy) &&
2217         "Invalid complex -> scalar conversion");
2218  return ScalarExprEmitter(*this).EmitComplexToScalarConversion(Src, SrcTy,
2219                                                                DstTy);
2220}
2221
2222
2223llvm::Value *CodeGenFunction::
2224EmitScalarPrePostIncDec(const UnaryOperator *E, LValue LV,
2225                        bool isInc, bool isPre) {
2226  return ScalarExprEmitter(*this).EmitScalarPrePostIncDec(E, LV, isInc, isPre);
2227}
2228
2229LValue CodeGenFunction::EmitObjCIsaExpr(const ObjCIsaExpr *E) {
2230  llvm::Value *V;
2231  // object->isa or (*object).isa
2232  // Generate code as for: *(Class*)object
2233  // build Class* type
2234  const llvm::Type *ClassPtrTy = ConvertType(E->getType());
2235
2236  Expr *BaseExpr = E->getBase();
2237  if (BaseExpr->isLvalue(getContext()) != Expr::LV_Valid) {
2238    V = CreateTempAlloca(ClassPtrTy, "resval");
2239    llvm::Value *Src = EmitScalarExpr(BaseExpr);
2240    Builder.CreateStore(Src, V);
2241    LValue LV = LValue::MakeAddr(V, MakeQualifiers(E->getType()));
2242    V = ScalarExprEmitter(*this).EmitLoadOfLValue(LV, E->getType());
2243  }
2244  else {
2245      if (E->isArrow())
2246        V = ScalarExprEmitter(*this).EmitLoadOfLValue(BaseExpr);
2247      else
2248        V  = EmitLValue(BaseExpr).getAddress();
2249  }
2250
2251  // build Class* type
2252  ClassPtrTy = ClassPtrTy->getPointerTo();
2253  V = Builder.CreateBitCast(V, ClassPtrTy);
2254  LValue LV = LValue::MakeAddr(V, MakeQualifiers(E->getType()));
2255  return LV;
2256}
2257
2258
2259LValue CodeGenFunction::EmitCompoundAssignOperatorLValue(
2260                                            const CompoundAssignOperator *E) {
2261  ScalarExprEmitter Scalar(*this);
2262  Value *Result = 0;
2263  switch (E->getOpcode()) {
2264#define COMPOUND_OP(Op)                                                       \
2265    case BinaryOperator::Op##Assign:                                          \
2266      return Scalar.EmitCompoundAssignLValue(E, &ScalarExprEmitter::Emit##Op, \
2267                                             Result)
2268  COMPOUND_OP(Mul);
2269  COMPOUND_OP(Div);
2270  COMPOUND_OP(Rem);
2271  COMPOUND_OP(Add);
2272  COMPOUND_OP(Sub);
2273  COMPOUND_OP(Shl);
2274  COMPOUND_OP(Shr);
2275  COMPOUND_OP(And);
2276  COMPOUND_OP(Xor);
2277  COMPOUND_OP(Or);
2278#undef COMPOUND_OP
2279
2280  case BinaryOperator::PtrMemD:
2281  case BinaryOperator::PtrMemI:
2282  case BinaryOperator::Mul:
2283  case BinaryOperator::Div:
2284  case BinaryOperator::Rem:
2285  case BinaryOperator::Add:
2286  case BinaryOperator::Sub:
2287  case BinaryOperator::Shl:
2288  case BinaryOperator::Shr:
2289  case BinaryOperator::LT:
2290  case BinaryOperator::GT:
2291  case BinaryOperator::LE:
2292  case BinaryOperator::GE:
2293  case BinaryOperator::EQ:
2294  case BinaryOperator::NE:
2295  case BinaryOperator::And:
2296  case BinaryOperator::Xor:
2297  case BinaryOperator::Or:
2298  case BinaryOperator::LAnd:
2299  case BinaryOperator::LOr:
2300  case BinaryOperator::Assign:
2301  case BinaryOperator::Comma:
2302    assert(false && "Not valid compound assignment operators");
2303    break;
2304  }
2305
2306  llvm_unreachable("Unhandled compound assignment operator");
2307}
2308