CGExprScalar.cpp revision b09fae74acfae7af8b3d31b9638a0aa0fdf7c7ac 
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 "CodeGenModule.h"
16#include "clang/AST/ASTContext.h"
17#include "clang/AST/DeclObjC.h"
18#include "clang/AST/StmtVisitor.h"
19#include "clang/Basic/TargetInfo.h"
20#include "llvm/Constants.h"
21#include "llvm/Function.h"
22#include "llvm/GlobalVariable.h"
23#include "llvm/Intrinsics.h"
24#include "llvm/Support/Compiler.h"
25#include "llvm/Support/CFG.h"
26#include <cstdarg>
27
28using namespace clang;
29using namespace CodeGen;
30using llvm::Value;
31
32//===----------------------------------------------------------------------===//
33//                         Scalar Expression Emitter
34//===----------------------------------------------------------------------===//
35
36struct BinOpInfo {
37  Value *LHS;
38  Value *RHS;
39  QualType Ty;  // Computation Type.
40  const BinaryOperator *E;
41};
42
43namespace {
44class VISIBILITY_HIDDEN ScalarExprEmitter
45  : public StmtVisitor<ScalarExprEmitter, Value*> {
46  CodeGenFunction &CGF;
47  CGBuilderTy &Builder;
48
49public:
50
51  ScalarExprEmitter(CodeGenFunction &cgf) : CGF(cgf),
52    Builder(CGF.Builder) {
53  }
54
55  //===--------------------------------------------------------------------===//
56  //                               Utilities
57  //===--------------------------------------------------------------------===//
58
59  const llvm::Type *ConvertType(QualType T) { return CGF.ConvertType(T); }
60  LValue EmitLValue(const Expr *E) { return CGF.EmitLValue(E); }
61
62  Value *EmitLoadOfLValue(LValue LV, QualType T) {
63    return CGF.EmitLoadOfLValue(LV, T).getScalarVal();
64  }
65
66  /// EmitLoadOfLValue - Given an expression with complex type that represents a
67  /// value l-value, this method emits the address of the l-value, then loads
68  /// and returns the result.
69  Value *EmitLoadOfLValue(const Expr *E) {
70    // FIXME: Volatile
71    return EmitLoadOfLValue(EmitLValue(E), E->getType());
72  }
73
74  /// EmitConversionToBool - Convert the specified expression value to a
75  /// boolean (i1) truth value.  This is equivalent to "Val != 0".
76  Value *EmitConversionToBool(Value *Src, QualType DstTy);
77
78  /// EmitScalarConversion - Emit a conversion from the specified type to the
79  /// specified destination type, both of which are LLVM scalar types.
80  Value *EmitScalarConversion(Value *Src, QualType SrcTy, QualType DstTy);
81
82  /// EmitComplexToScalarConversion - Emit a conversion from the specified
83  /// complex type to the specified destination type, where the destination
84  /// type is an LLVM scalar type.
85  Value *EmitComplexToScalarConversion(CodeGenFunction::ComplexPairTy Src,
86                                       QualType SrcTy, QualType DstTy);
87
88  //===--------------------------------------------------------------------===//
89  //                            Visitor Methods
90  //===--------------------------------------------------------------------===//
91
92  Value *VisitStmt(Stmt *S) {
93    S->dump(CGF.getContext().getSourceManager());
94    assert(0 && "Stmt can't have complex result type!");
95    return 0;
96  }
97  Value *VisitExpr(Expr *S);
98  Value *VisitParenExpr(ParenExpr *PE) { return Visit(PE->getSubExpr()); }
99
100  // Leaves.
101  Value *VisitIntegerLiteral(const IntegerLiteral *E) {
102    return llvm::ConstantInt::get(E->getValue());
103  }
104  Value *VisitFloatingLiteral(const FloatingLiteral *E) {
105    return llvm::ConstantFP::get(E->getValue());
106  }
107  Value *VisitCharacterLiteral(const CharacterLiteral *E) {
108    return llvm::ConstantInt::get(ConvertType(E->getType()), E->getValue());
109  }
110  Value *VisitCXXBoolLiteralExpr(const CXXBoolLiteralExpr *E) {
111    return llvm::ConstantInt::get(ConvertType(E->getType()), E->getValue());
112  }
113  Value *VisitCXXZeroInitValueExpr(const CXXZeroInitValueExpr *E) {
114    return llvm::Constant::getNullValue(ConvertType(E->getType()));
115  }
116  Value *VisitGNUNullExpr(const GNUNullExpr *E) {
117    return llvm::Constant::getNullValue(ConvertType(E->getType()));
118  }
119  Value *VisitTypesCompatibleExpr(const TypesCompatibleExpr *E) {
120    return llvm::ConstantInt::get(ConvertType(E->getType()),
121                                  CGF.getContext().typesAreCompatible(
122                                    E->getArgType1(), E->getArgType2()));
123  }
124  Value *VisitSizeOfAlignOfExpr(const SizeOfAlignOfExpr *E);
125  Value *VisitAddrLabelExpr(const AddrLabelExpr *E) {
126    llvm::Value *V =
127      llvm::ConstantInt::get(llvm::Type::Int32Ty,
128                             CGF.GetIDForAddrOfLabel(E->getLabel()));
129
130    return Builder.CreateIntToPtr(V, ConvertType(E->getType()));
131  }
132
133  // l-values.
134  Value *VisitDeclRefExpr(DeclRefExpr *E) {
135    if (const EnumConstantDecl *EC = dyn_cast<EnumConstantDecl>(E->getDecl()))
136      return llvm::ConstantInt::get(EC->getInitVal());
137    return EmitLoadOfLValue(E);
138  }
139  Value *VisitObjCSelectorExpr(ObjCSelectorExpr *E) {
140    return CGF.EmitObjCSelectorExpr(E);
141  }
142  Value *VisitObjCProtocolExpr(ObjCProtocolExpr *E) {
143    return CGF.EmitObjCProtocolExpr(E);
144  }
145  Value *VisitObjCIvarRefExpr(ObjCIvarRefExpr *E) {
146    return EmitLoadOfLValue(E);
147  }
148  Value *VisitObjCPropertyRefExpr(ObjCPropertyRefExpr *E) {
149    return EmitLoadOfLValue(E);
150  }
151  Value *VisitObjCKVCRefExpr(ObjCKVCRefExpr *E) {
152    return EmitLoadOfLValue(E);
153  }
154  Value *VisitObjCMessageExpr(ObjCMessageExpr *E) {
155    return CGF.EmitObjCMessageExpr(E).getScalarVal();
156  }
157
158  Value *VisitArraySubscriptExpr(ArraySubscriptExpr *E);
159  Value *VisitShuffleVectorExpr(ShuffleVectorExpr *E);
160  Value *VisitMemberExpr(Expr *E)           { return EmitLoadOfLValue(E); }
161  Value *VisitExtVectorElementExpr(Expr *E) { return EmitLoadOfLValue(E); }
162  Value *VisitCompoundLiteralExpr(CompoundLiteralExpr *E) {
163    return EmitLoadOfLValue(E);
164  }
165  Value *VisitStringLiteral(Expr *E)  { return EmitLValue(E).getAddress(); }
166  Value *VisitPredefinedExpr(Expr *E) { return EmitLValue(E).getAddress(); }
167
168  Value *VisitInitListExpr(InitListExpr *E) {
169    unsigned NumInitElements = E->getNumInits();
170
171    const llvm::VectorType *VType =
172      dyn_cast<llvm::VectorType>(ConvertType(E->getType()));
173
174    // We have a scalar in braces. Just use the first element.
175    if (!VType)
176      return Visit(E->getInit(0));
177
178    if (E->hadDesignators()) {
179      CGF.ErrorUnsupported(E, "initializer list with designators");
180      return llvm::UndefValue::get(CGF.ConvertType(E->getType()));
181    }
182
183    unsigned NumVectorElements = VType->getNumElements();
184    const llvm::Type *ElementType = VType->getElementType();
185
186    // Emit individual vector element stores.
187    llvm::Value *V = llvm::UndefValue::get(VType);
188
189    // Emit initializers
190    unsigned i;
191    for (i = 0; i < NumInitElements; ++i) {
192      Value *NewV = Visit(E->getInit(i));
193      Value *Idx = llvm::ConstantInt::get(llvm::Type::Int32Ty, i);
194      V = Builder.CreateInsertElement(V, NewV, Idx);
195    }
196
197    // Emit remaining default initializers
198    for (/* Do not initialize i*/; i < NumVectorElements; ++i) {
199      Value *Idx = llvm::ConstantInt::get(llvm::Type::Int32Ty, i);
200      llvm::Value *NewV = llvm::Constant::getNullValue(ElementType);
201      V = Builder.CreateInsertElement(V, NewV, Idx);
202    }
203
204    return V;
205  }
206
207  Value *VisitImplicitCastExpr(const ImplicitCastExpr *E);
208  Value *VisitCastExpr(const CastExpr *E) {
209    return EmitCastExpr(E->getSubExpr(), E->getType());
210  }
211  Value *EmitCastExpr(const Expr *E, QualType T);
212
213  Value *VisitCallExpr(const CallExpr *E) {
214    return CGF.EmitCallExpr(E).getScalarVal();
215  }
216
217  Value *VisitStmtExpr(const StmtExpr *E);
218
219  // Unary Operators.
220  Value *VisitPrePostIncDec(const UnaryOperator *E, bool isInc, bool isPre);
221  Value *VisitUnaryPostDec(const UnaryOperator *E) {
222    return VisitPrePostIncDec(E, false, false);
223  }
224  Value *VisitUnaryPostInc(const UnaryOperator *E) {
225    return VisitPrePostIncDec(E, true, false);
226  }
227  Value *VisitUnaryPreDec(const UnaryOperator *E) {
228    return VisitPrePostIncDec(E, false, true);
229  }
230  Value *VisitUnaryPreInc(const UnaryOperator *E) {
231    return VisitPrePostIncDec(E, true, true);
232  }
233  Value *VisitUnaryAddrOf(const UnaryOperator *E) {
234    return EmitLValue(E->getSubExpr()).getAddress();
235  }
236  Value *VisitUnaryDeref(const Expr *E) { return EmitLoadOfLValue(E); }
237  Value *VisitUnaryPlus(const UnaryOperator *E) {
238    return Visit(E->getSubExpr());
239  }
240  Value *VisitUnaryMinus    (const UnaryOperator *E);
241  Value *VisitUnaryNot      (const UnaryOperator *E);
242  Value *VisitUnaryLNot     (const UnaryOperator *E);
243  Value *VisitUnaryReal     (const UnaryOperator *E);
244  Value *VisitUnaryImag     (const UnaryOperator *E);
245  Value *VisitUnaryExtension(const UnaryOperator *E) {
246    return Visit(E->getSubExpr());
247  }
248  Value *VisitUnaryOffsetOf(const UnaryOperator *E);
249  Value *VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) {
250    return Visit(DAE->getExpr());
251  }
252
253  // Binary Operators.
254  Value *EmitMul(const BinOpInfo &Ops) {
255    return Builder.CreateMul(Ops.LHS, Ops.RHS, "mul");
256  }
257  Value *EmitDiv(const BinOpInfo &Ops);
258  Value *EmitRem(const BinOpInfo &Ops);
259  Value *EmitAdd(const BinOpInfo &Ops);
260  Value *EmitSub(const BinOpInfo &Ops);
261  Value *EmitShl(const BinOpInfo &Ops);
262  Value *EmitShr(const BinOpInfo &Ops);
263  Value *EmitAnd(const BinOpInfo &Ops) {
264    return Builder.CreateAnd(Ops.LHS, Ops.RHS, "and");
265  }
266  Value *EmitXor(const BinOpInfo &Ops) {
267    return Builder.CreateXor(Ops.LHS, Ops.RHS, "xor");
268  }
269  Value *EmitOr (const BinOpInfo &Ops) {
270    return Builder.CreateOr(Ops.LHS, Ops.RHS, "or");
271  }
272
273  BinOpInfo EmitBinOps(const BinaryOperator *E);
274  Value *EmitCompoundAssign(const CompoundAssignOperator *E,
275                            Value *(ScalarExprEmitter::*F)(const BinOpInfo &));
276
277  // Binary operators and binary compound assignment operators.
278#define HANDLEBINOP(OP) \
279  Value *VisitBin ## OP(const BinaryOperator *E) {                         \
280    return Emit ## OP(EmitBinOps(E));                                      \
281  }                                                                        \
282  Value *VisitBin ## OP ## Assign(const CompoundAssignOperator *E) {       \
283    return EmitCompoundAssign(E, &ScalarExprEmitter::Emit ## OP);          \
284  }
285  HANDLEBINOP(Mul);
286  HANDLEBINOP(Div);
287  HANDLEBINOP(Rem);
288  HANDLEBINOP(Add);
289  HANDLEBINOP(Sub);
290  HANDLEBINOP(Shl);
291  HANDLEBINOP(Shr);
292  HANDLEBINOP(And);
293  HANDLEBINOP(Xor);
294  HANDLEBINOP(Or);
295#undef HANDLEBINOP
296
297  // Comparisons.
298  Value *EmitCompare(const BinaryOperator *E, unsigned UICmpOpc,
299                     unsigned SICmpOpc, unsigned FCmpOpc);
300#define VISITCOMP(CODE, UI, SI, FP) \
301    Value *VisitBin##CODE(const BinaryOperator *E) { \
302      return EmitCompare(E, llvm::ICmpInst::UI, llvm::ICmpInst::SI, \
303                         llvm::FCmpInst::FP); }
304  VISITCOMP(LT, ICMP_ULT, ICMP_SLT, FCMP_OLT);
305  VISITCOMP(GT, ICMP_UGT, ICMP_SGT, FCMP_OGT);
306  VISITCOMP(LE, ICMP_ULE, ICMP_SLE, FCMP_OLE);
307  VISITCOMP(GE, ICMP_UGE, ICMP_SGE, FCMP_OGE);
308  VISITCOMP(EQ, ICMP_EQ , ICMP_EQ , FCMP_OEQ);
309  VISITCOMP(NE, ICMP_NE , ICMP_NE , FCMP_UNE);
310#undef VISITCOMP
311
312  Value *VisitBinAssign     (const BinaryOperator *E);
313
314  Value *VisitBinLAnd       (const BinaryOperator *E);
315  Value *VisitBinLOr        (const BinaryOperator *E);
316  Value *VisitBinComma      (const BinaryOperator *E);
317
318  // Other Operators.
319  Value *VisitBlockExpr(const BlockExpr *BE) {
320    CGF.ErrorUnsupported(BE, "block expression");
321    return llvm::UndefValue::get(CGF.ConvertType(BE->getType()));
322  }
323
324  Value *VisitConditionalOperator(const ConditionalOperator *CO);
325  Value *VisitChooseExpr(ChooseExpr *CE);
326  Value *VisitOverloadExpr(OverloadExpr *OE);
327  Value *VisitVAArgExpr(VAArgExpr *VE);
328  Value *VisitObjCStringLiteral(const ObjCStringLiteral *E) {
329    return CGF.EmitObjCStringLiteral(E);
330  }
331  Value *VisitObjCEncodeExpr(const ObjCEncodeExpr *E);
332};
333}  // end anonymous namespace.
334
335//===----------------------------------------------------------------------===//
336//                                Utilities
337//===----------------------------------------------------------------------===//
338
339/// EmitConversionToBool - Convert the specified expression value to a
340/// boolean (i1) truth value.  This is equivalent to "Val != 0".
341Value *ScalarExprEmitter::EmitConversionToBool(Value *Src, QualType SrcType) {
342  assert(SrcType->isCanonical() && "EmitScalarConversion strips typedefs");
343
344  if (SrcType->isRealFloatingType()) {
345    // Compare against 0.0 for fp scalars.
346    llvm::Value *Zero = llvm::Constant::getNullValue(Src->getType());
347    return Builder.CreateFCmpUNE(Src, Zero, "tobool");
348  }
349
350  assert((SrcType->isIntegerType() || isa<llvm::PointerType>(Src->getType())) &&
351         "Unknown scalar type to convert");
352
353  // Because of the type rules of C, we often end up computing a logical value,
354  // then zero extending it to int, then wanting it as a logical value again.
355  // Optimize this common case.
356  if (llvm::ZExtInst *ZI = dyn_cast<llvm::ZExtInst>(Src)) {
357    if (ZI->getOperand(0)->getType() == llvm::Type::Int1Ty) {
358      Value *Result = ZI->getOperand(0);
359      // If there aren't any more uses, zap the instruction to save space.
360      // Note that there can be more uses, for example if this
361      // is the result of an assignment.
362      if (ZI->use_empty())
363        ZI->eraseFromParent();
364      return Result;
365    }
366  }
367
368  // Compare against an integer or pointer null.
369  llvm::Value *Zero = llvm::Constant::getNullValue(Src->getType());
370  return Builder.CreateICmpNE(Src, Zero, "tobool");
371}
372
373/// EmitScalarConversion - Emit a conversion from the specified type to the
374/// specified destination type, both of which are LLVM scalar types.
375Value *ScalarExprEmitter::EmitScalarConversion(Value *Src, QualType SrcType,
376                                               QualType DstType) {
377  SrcType = CGF.getContext().getCanonicalType(SrcType);
378  DstType = CGF.getContext().getCanonicalType(DstType);
379  if (SrcType == DstType) return Src;
380
381  if (DstType->isVoidType()) return 0;
382
383  // Handle conversions to bool first, they are special: comparisons against 0.
384  if (DstType->isBooleanType())
385    return EmitConversionToBool(Src, SrcType);
386
387  const llvm::Type *DstTy = ConvertType(DstType);
388
389  // Ignore conversions like int -> uint.
390  if (Src->getType() == DstTy)
391    return Src;
392
393  // Handle pointer conversions next: pointers can only be converted
394  // to/from other pointers and integers. Check for pointer types in
395  // terms of LLVM, as some native types (like Obj-C id) may map to a
396  // pointer type.
397  if (isa<llvm::PointerType>(DstTy)) {
398    // The source value may be an integer, or a pointer.
399    if (isa<llvm::PointerType>(Src->getType()))
400      return Builder.CreateBitCast(Src, DstTy, "conv");
401    assert(SrcType->isIntegerType() && "Not ptr->ptr or int->ptr conversion?");
402    return Builder.CreateIntToPtr(Src, DstTy, "conv");
403  }
404
405  if (isa<llvm::PointerType>(Src->getType())) {
406    // Must be an ptr to int cast.
407    assert(isa<llvm::IntegerType>(DstTy) && "not ptr->int?");
408    return Builder.CreatePtrToInt(Src, DstTy, "conv");
409  }
410
411  // A scalar can be splatted to an extended vector of the same element type
412  if (DstType->isExtVectorType() && !isa<VectorType>(SrcType)) {
413    // Cast the scalar to element type
414    QualType EltTy = DstType->getAsExtVectorType()->getElementType();
415    llvm::Value *Elt = EmitScalarConversion(Src, SrcType, EltTy);
416
417    // Insert the element in element zero of an undef vector
418    llvm::Value *UnV = llvm::UndefValue::get(DstTy);
419    llvm::Value *Idx = llvm::ConstantInt::get(llvm::Type::Int32Ty, 0);
420    UnV = Builder.CreateInsertElement(UnV, Elt, Idx, "tmp");
421
422    // Splat the element across to all elements
423    llvm::SmallVector<llvm::Constant*, 16> Args;
424    unsigned NumElements = cast<llvm::VectorType>(DstTy)->getNumElements();
425    for (unsigned i = 0; i < NumElements; i++)
426      Args.push_back(llvm::ConstantInt::get(llvm::Type::Int32Ty, 0));
427
428    llvm::Constant *Mask = llvm::ConstantVector::get(&Args[0], NumElements);
429    llvm::Value *Yay = Builder.CreateShuffleVector(UnV, UnV, Mask, "splat");
430    return Yay;
431  }
432
433  // Allow bitcast from vector to integer/fp of the same size.
434  if (isa<llvm::VectorType>(Src->getType()) ||
435      isa<llvm::VectorType>(DstTy))
436    return Builder.CreateBitCast(Src, DstTy, "conv");
437
438  // Finally, we have the arithmetic types: real int/float.
439  if (isa<llvm::IntegerType>(Src->getType())) {
440    bool InputSigned = SrcType->isSignedIntegerType();
441    if (isa<llvm::IntegerType>(DstTy))
442      return Builder.CreateIntCast(Src, DstTy, InputSigned, "conv");
443    else if (InputSigned)
444      return Builder.CreateSIToFP(Src, DstTy, "conv");
445    else
446      return Builder.CreateUIToFP(Src, DstTy, "conv");
447  }
448
449  assert(Src->getType()->isFloatingPoint() && "Unknown real conversion");
450  if (isa<llvm::IntegerType>(DstTy)) {
451    if (DstType->isSignedIntegerType())
452      return Builder.CreateFPToSI(Src, DstTy, "conv");
453    else
454      return Builder.CreateFPToUI(Src, DstTy, "conv");
455  }
456
457  assert(DstTy->isFloatingPoint() && "Unknown real conversion");
458  if (DstTy->getTypeID() < Src->getType()->getTypeID())
459    return Builder.CreateFPTrunc(Src, DstTy, "conv");
460  else
461    return Builder.CreateFPExt(Src, DstTy, "conv");
462}
463
464/// EmitComplexToScalarConversion - Emit a conversion from the specified
465/// complex type to the specified destination type, where the destination
466/// type is an LLVM scalar type.
467Value *ScalarExprEmitter::
468EmitComplexToScalarConversion(CodeGenFunction::ComplexPairTy Src,
469                              QualType SrcTy, QualType DstTy) {
470  // Get the source element type.
471  SrcTy = SrcTy->getAsComplexType()->getElementType();
472
473  // Handle conversions to bool first, they are special: comparisons against 0.
474  if (DstTy->isBooleanType()) {
475    //  Complex != 0  -> (Real != 0) | (Imag != 0)
476    Src.first  = EmitScalarConversion(Src.first, SrcTy, DstTy);
477    Src.second = EmitScalarConversion(Src.second, SrcTy, DstTy);
478    return Builder.CreateOr(Src.first, Src.second, "tobool");
479  }
480
481  // C99 6.3.1.7p2: "When a value of complex type is converted to a real type,
482  // the imaginary part of the complex value is discarded and the value of the
483  // real part is converted according to the conversion rules for the
484  // corresponding real type.
485  return EmitScalarConversion(Src.first, SrcTy, DstTy);
486}
487
488
489//===----------------------------------------------------------------------===//
490//                            Visitor Methods
491//===----------------------------------------------------------------------===//
492
493Value *ScalarExprEmitter::VisitExpr(Expr *E) {
494  CGF.ErrorUnsupported(E, "scalar expression");
495  if (E->getType()->isVoidType())
496    return 0;
497  return llvm::UndefValue::get(CGF.ConvertType(E->getType()));
498}
499
500Value *ScalarExprEmitter::VisitShuffleVectorExpr(ShuffleVectorExpr *E) {
501  llvm::SmallVector<llvm::Constant*, 32> indices;
502  for (unsigned i = 2; i < E->getNumSubExprs(); i++) {
503    indices.push_back(cast<llvm::Constant>(CGF.EmitScalarExpr(E->getExpr(i))));
504  }
505  Value* V1 = CGF.EmitScalarExpr(E->getExpr(0));
506  Value* V2 = CGF.EmitScalarExpr(E->getExpr(1));
507  Value* SV = llvm::ConstantVector::get(indices.begin(), indices.size());
508  return Builder.CreateShuffleVector(V1, V2, SV, "shuffle");
509}
510
511Value *ScalarExprEmitter::VisitArraySubscriptExpr(ArraySubscriptExpr *E) {
512  // Emit subscript expressions in rvalue context's.  For most cases, this just
513  // loads the lvalue formed by the subscript expr.  However, we have to be
514  // careful, because the base of a vector subscript is occasionally an rvalue,
515  // so we can't get it as an lvalue.
516  if (!E->getBase()->getType()->isVectorType())
517    return EmitLoadOfLValue(E);
518
519  // Handle the vector case.  The base must be a vector, the index must be an
520  // integer value.
521  Value *Base = Visit(E->getBase());
522  Value *Idx  = Visit(E->getIdx());
523
524  // FIXME: Convert Idx to i32 type.
525  return Builder.CreateExtractElement(Base, Idx, "vecext");
526}
527
528/// VisitImplicitCastExpr - Implicit casts are the same as normal casts, but
529/// also handle things like function to pointer-to-function decay, and array to
530/// pointer decay.
531Value *ScalarExprEmitter::VisitImplicitCastExpr(const ImplicitCastExpr *E) {
532  const Expr *Op = E->getSubExpr();
533
534  // If this is due to array->pointer conversion, emit the array expression as
535  // an l-value.
536  if (Op->getType()->isArrayType()) {
537    // FIXME: For now we assume that all source arrays map to LLVM arrays.  This
538    // will not true when we add support for VLAs.
539    Value *V = EmitLValue(Op).getAddress();  // Bitfields can't be arrays.
540
541    if (!Op->getType()->isVariableArrayType()) {
542      assert(isa<llvm::PointerType>(V->getType()) && "Expected pointer");
543      assert(isa<llvm::ArrayType>(cast<llvm::PointerType>(V->getType())
544                                 ->getElementType()) &&
545             "Expected pointer to array");
546      V = Builder.CreateStructGEP(V, 0, "arraydecay");
547    }
548
549    // The resultant pointer type can be implicitly casted to other pointer
550    // types as well (e.g. void*) and can be implicitly converted to integer.
551    const llvm::Type *DestTy = ConvertType(E->getType());
552    if (V->getType() != DestTy) {
553      if (isa<llvm::PointerType>(DestTy))
554        V = Builder.CreateBitCast(V, DestTy, "ptrconv");
555      else {
556        assert(isa<llvm::IntegerType>(DestTy) && "Unknown array decay");
557        V = Builder.CreatePtrToInt(V, DestTy, "ptrconv");
558      }
559    }
560    return V;
561
562  } else if (E->getType()->isReferenceType()) {
563    return EmitLValue(Op).getAddress();
564  }
565
566  return EmitCastExpr(Op, E->getType());
567}
568
569
570// VisitCastExpr - Emit code for an explicit or implicit cast.  Implicit casts
571// have to handle a more broad range of conversions than explicit casts, as they
572// handle things like function to ptr-to-function decay etc.
573Value *ScalarExprEmitter::EmitCastExpr(const Expr *E, QualType DestTy) {
574  // Handle cases where the source is an non-complex type.
575
576  if (!CGF.hasAggregateLLVMType(E->getType())) {
577    Value *Src = Visit(const_cast<Expr*>(E));
578
579    // Use EmitScalarConversion to perform the conversion.
580    return EmitScalarConversion(Src, E->getType(), DestTy);
581  }
582
583  if (E->getType()->isAnyComplexType()) {
584    // Handle cases where the source is a complex type.
585    return EmitComplexToScalarConversion(CGF.EmitComplexExpr(E), E->getType(),
586                                         DestTy);
587  }
588
589  // Okay, this is a cast from an aggregate.  It must be a cast to void.  Just
590  // evaluate the result and return.
591  CGF.EmitAggExpr(E, 0, false);
592  return 0;
593}
594
595Value *ScalarExprEmitter::VisitStmtExpr(const StmtExpr *E) {
596  return CGF.EmitCompoundStmt(*E->getSubStmt(),
597                              !E->getType()->isVoidType()).getScalarVal();
598}
599
600
601//===----------------------------------------------------------------------===//
602//                             Unary Operators
603//===----------------------------------------------------------------------===//
604
605Value *ScalarExprEmitter::VisitPrePostIncDec(const UnaryOperator *E,
606                                             bool isInc, bool isPre) {
607  LValue LV = EmitLValue(E->getSubExpr());
608  // FIXME: Handle volatile!
609  Value *InVal = CGF.EmitLoadOfLValue(LV, // false
610                                     E->getSubExpr()->getType()).getScalarVal();
611
612  int AmountVal = isInc ? 1 : -1;
613
614  Value *NextVal;
615  if (isa<llvm::PointerType>(InVal->getType())) {
616    // FIXME: This isn't right for VLAs.
617    NextVal = llvm::ConstantInt::get(llvm::Type::Int32Ty, AmountVal);
618    NextVal = Builder.CreateGEP(InVal, NextVal, "ptrincdec");
619  } else {
620    // Add the inc/dec to the real part.
621    if (isa<llvm::IntegerType>(InVal->getType()))
622      NextVal = llvm::ConstantInt::get(InVal->getType(), AmountVal);
623    else if (InVal->getType() == llvm::Type::FloatTy)
624      NextVal =
625        llvm::ConstantFP::get(llvm::APFloat(static_cast<float>(AmountVal)));
626    else if (InVal->getType() == llvm::Type::DoubleTy)
627      NextVal =
628        llvm::ConstantFP::get(llvm::APFloat(static_cast<double>(AmountVal)));
629    else {
630      llvm::APFloat F(static_cast<float>(AmountVal));
631      bool ignored;
632      F.convert(CGF.Target.getLongDoubleFormat(), llvm::APFloat::rmTowardZero,
633                &ignored);
634      NextVal = llvm::ConstantFP::get(F);
635    }
636    NextVal = Builder.CreateAdd(InVal, NextVal, isInc ? "inc" : "dec");
637  }
638
639  // Store the updated result through the lvalue.
640  CGF.EmitStoreThroughLValue(RValue::get(NextVal), LV,
641                             E->getSubExpr()->getType());
642
643  // If this is a postinc, return the value read from memory, otherwise use the
644  // updated value.
645  return isPre ? NextVal : InVal;
646}
647
648
649Value *ScalarExprEmitter::VisitUnaryMinus(const UnaryOperator *E) {
650  Value *Op = Visit(E->getSubExpr());
651  return Builder.CreateNeg(Op, "neg");
652}
653
654Value *ScalarExprEmitter::VisitUnaryNot(const UnaryOperator *E) {
655  Value *Op = Visit(E->getSubExpr());
656  return Builder.CreateNot(Op, "neg");
657}
658
659Value *ScalarExprEmitter::VisitUnaryLNot(const UnaryOperator *E) {
660  // Compare operand to zero.
661  Value *BoolVal = CGF.EvaluateExprAsBool(E->getSubExpr());
662
663  // Invert value.
664  // TODO: Could dynamically modify easy computations here.  For example, if
665  // the operand is an icmp ne, turn into icmp eq.
666  BoolVal = Builder.CreateNot(BoolVal, "lnot");
667
668  // ZExt result to int.
669  return Builder.CreateZExt(BoolVal, CGF.LLVMIntTy, "lnot.ext");
670}
671
672/// VisitSizeOfAlignOfExpr - Return the size or alignment of the type of
673/// argument of the sizeof expression as an integer.
674Value *
675ScalarExprEmitter::VisitSizeOfAlignOfExpr(const SizeOfAlignOfExpr *E) {
676  QualType RetType = E->getType();
677  assert(RetType->isIntegerType() && "Result type must be an integer!");
678  uint32_t ResultWidth =
679    static_cast<uint32_t>(CGF.getContext().getTypeSize(RetType));
680
681  QualType TypeToSize = E->getTypeOfArgument();
682  // sizeof(void) and __alignof__(void) = 1 as a gcc extension. Also
683  // for function types.
684  // FIXME: what is alignof a function type in gcc?
685  if (TypeToSize->isVoidType() || TypeToSize->isFunctionType())
686    return llvm::ConstantInt::get(llvm::APInt(ResultWidth, 1));
687
688  if (const VariableArrayType *VAT =
689        CGF.getContext().getAsVariableArrayType(TypeToSize)) {
690    if (E->isSizeOf()) {
691      if (E->isArgumentType()) {
692        // sizeof(type) - make sure to emit the VLA size.
693        CGF.EmitVLASize(TypeToSize);
694      }
695      return CGF.GetVLASize(VAT);
696    }
697
698    // alignof
699    QualType BaseType = CGF.getContext().getBaseElementType(VAT);
700    uint64_t Align = CGF.getContext().getTypeAlign(BaseType);
701
702    Align /= 8;  // Return alignment in bytes, not bits.
703    return llvm::ConstantInt::get(llvm::APInt(ResultWidth, Align));
704  }
705  if (TypeToSize->isObjCInterfaceType()) {
706    ObjCInterfaceDecl *OI = TypeToSize->getAsObjCInterfaceType()->getDecl();
707    RecordDecl *RD = const_cast<RecordDecl*>(
708                                        CGF.getContext().addRecordToClass(OI));
709    TypeToSize =  CGF.getContext().getTagDeclType(static_cast<TagDecl*>(RD));
710  }
711  std::pair<uint64_t, unsigned> Info = CGF.getContext().getTypeInfo(TypeToSize);
712
713  uint64_t Val = E->isSizeOf() ? Info.first : Info.second;
714  Val /= 8;  // Return size in bytes, not bits.
715
716  return llvm::ConstantInt::get(llvm::APInt(ResultWidth, Val));
717}
718
719Value *ScalarExprEmitter::VisitUnaryReal(const UnaryOperator *E) {
720  Expr *Op = E->getSubExpr();
721  if (Op->getType()->isAnyComplexType())
722    return CGF.EmitComplexExpr(Op).first;
723  return Visit(Op);
724}
725Value *ScalarExprEmitter::VisitUnaryImag(const UnaryOperator *E) {
726  Expr *Op = E->getSubExpr();
727  if (Op->getType()->isAnyComplexType())
728    return CGF.EmitComplexExpr(Op).second;
729
730  // __imag on a scalar returns zero.  Emit it the subexpr to ensure side
731  // effects are evaluated.
732  CGF.EmitScalarExpr(Op);
733  return llvm::Constant::getNullValue(ConvertType(E->getType()));
734}
735
736Value *ScalarExprEmitter::VisitUnaryOffsetOf(const UnaryOperator *E)
737{
738  int64_t Val = E->evaluateOffsetOf(CGF.getContext());
739
740  assert(E->getType()->isIntegerType() && "Result type must be an integer!");
741
742  uint32_t ResultWidth =
743    static_cast<uint32_t>(CGF.getContext().getTypeSize(E->getType()));
744  return llvm::ConstantInt::get(llvm::APInt(ResultWidth, Val));
745}
746
747//===----------------------------------------------------------------------===//
748//                           Binary Operators
749//===----------------------------------------------------------------------===//
750
751BinOpInfo ScalarExprEmitter::EmitBinOps(const BinaryOperator *E) {
752  BinOpInfo Result;
753  Result.LHS = Visit(E->getLHS());
754  Result.RHS = Visit(E->getRHS());
755  Result.Ty  = E->getType();
756  Result.E = E;
757  return Result;
758}
759
760Value *ScalarExprEmitter::EmitCompoundAssign(const CompoundAssignOperator *E,
761                      Value *(ScalarExprEmitter::*Func)(const BinOpInfo &)) {
762  QualType LHSTy = E->getLHS()->getType(), RHSTy = E->getRHS()->getType();
763
764  BinOpInfo OpInfo;
765
766  // Load the LHS and RHS operands.
767  LValue LHSLV = EmitLValue(E->getLHS());
768  OpInfo.LHS = EmitLoadOfLValue(LHSLV, LHSTy);
769
770  // Determine the computation type.  If the RHS is complex, then this is one of
771  // the add/sub/mul/div operators.  All of these operators can be computed in
772  // with just their real component even though the computation domain really is
773  // complex.
774  QualType ComputeType = E->getComputationType();
775
776  // If the computation type is complex, then the RHS is complex.  Emit the RHS.
777  if (const ComplexType *CT = ComputeType->getAsComplexType()) {
778    ComputeType = CT->getElementType();
779
780    // Emit the RHS, only keeping the real component.
781    OpInfo.RHS = CGF.EmitComplexExpr(E->getRHS()).first;
782    RHSTy = RHSTy->getAsComplexType()->getElementType();
783  } else {
784    // Otherwise the RHS is a simple scalar value.
785    OpInfo.RHS = Visit(E->getRHS());
786  }
787
788  QualType LComputeTy, RComputeTy, ResultTy;
789
790  // Compound assignment does not contain enough information about all
791  // the types involved for pointer arithmetic cases. Figure it out
792  // here for now.
793  if (E->getLHS()->getType()->isPointerType()) {
794    // Pointer arithmetic cases: ptr +=,-= int and ptr -= ptr,
795    assert((E->getOpcode() == BinaryOperator::AddAssign ||
796            E->getOpcode() == BinaryOperator::SubAssign) &&
797           "Invalid compound assignment operator on pointer type.");
798    LComputeTy = E->getLHS()->getType();
799
800    if (E->getRHS()->getType()->isPointerType()) {
801      // Degenerate case of (ptr -= ptr) allowed by GCC implicit cast
802      // extension, the conversion from the pointer difference back to
803      // the LHS type is handled at the end.
804      assert(E->getOpcode() == BinaryOperator::SubAssign &&
805             "Invalid compound assignment operator on pointer type.");
806      RComputeTy = E->getLHS()->getType();
807      ResultTy = CGF.getContext().getPointerDiffType();
808    } else {
809      RComputeTy = E->getRHS()->getType();
810      ResultTy = LComputeTy;
811    }
812  } else if (E->getRHS()->getType()->isPointerType()) {
813    // Degenerate case of (int += ptr) allowed by GCC implicit cast
814    // extension.
815    assert(E->getOpcode() == BinaryOperator::AddAssign &&
816           "Invalid compound assignment operator on pointer type.");
817    LComputeTy = E->getLHS()->getType();
818    RComputeTy = E->getRHS()->getType();
819    ResultTy = RComputeTy;
820  } else {
821    LComputeTy = RComputeTy = ResultTy = ComputeType;
822  }
823
824  // Convert the LHS/RHS values to the computation type.
825  OpInfo.LHS = EmitScalarConversion(OpInfo.LHS, LHSTy, LComputeTy);
826  OpInfo.RHS = EmitScalarConversion(OpInfo.RHS, RHSTy, RComputeTy);
827  OpInfo.Ty = ResultTy;
828  OpInfo.E = E;
829
830  // Expand the binary operator.
831  Value *Result = (this->*Func)(OpInfo);
832
833  // Convert the result back to the LHS type.
834  Result = EmitScalarConversion(Result, ResultTy, LHSTy);
835
836  // Store the result value into the LHS lvalue. Bit-fields are
837  // handled specially because the result is altered by the store,
838  // i.e., [C99 6.5.16p1] 'An assignment expression has the value of
839  // the left operand after the assignment...'.
840  if (LHSLV.isBitfield())
841    CGF.EmitStoreThroughBitfieldLValue(RValue::get(Result), LHSLV, LHSTy,
842                                       &Result);
843  else
844    CGF.EmitStoreThroughLValue(RValue::get(Result), LHSLV, LHSTy);
845
846  return Result;
847}
848
849
850Value *ScalarExprEmitter::EmitDiv(const BinOpInfo &Ops) {
851  if (Ops.LHS->getType()->isFPOrFPVector())
852    return Builder.CreateFDiv(Ops.LHS, Ops.RHS, "div");
853  else if (Ops.Ty->isUnsignedIntegerType())
854    return Builder.CreateUDiv(Ops.LHS, Ops.RHS, "div");
855  else
856    return Builder.CreateSDiv(Ops.LHS, Ops.RHS, "div");
857}
858
859Value *ScalarExprEmitter::EmitRem(const BinOpInfo &Ops) {
860  // Rem in C can't be a floating point type: C99 6.5.5p2.
861  if (Ops.Ty->isUnsignedIntegerType())
862    return Builder.CreateURem(Ops.LHS, Ops.RHS, "rem");
863  else
864    return Builder.CreateSRem(Ops.LHS, Ops.RHS, "rem");
865}
866
867
868Value *ScalarExprEmitter::EmitAdd(const BinOpInfo &Ops) {
869  if (!Ops.Ty->isPointerType())
870    return Builder.CreateAdd(Ops.LHS, Ops.RHS, "add");
871
872  // FIXME: What about a pointer to a VLA?
873  Value *Ptr, *Idx;
874  Expr *IdxExp;
875  const PointerType *PT;
876  if ((PT = Ops.E->getLHS()->getType()->getAsPointerType())) {
877    Ptr = Ops.LHS;
878    Idx = Ops.RHS;
879    IdxExp = Ops.E->getRHS();
880  } else {                                           // int + pointer
881    PT = Ops.E->getRHS()->getType()->getAsPointerType();
882    assert(PT && "Invalid add expr");
883    Ptr = Ops.RHS;
884    Idx = Ops.LHS;
885    IdxExp = Ops.E->getLHS();
886  }
887
888  unsigned Width = cast<llvm::IntegerType>(Idx->getType())->getBitWidth();
889  if (Width < CGF.LLVMPointerWidth) {
890    // Zero or sign extend the pointer value based on whether the index is
891    // signed or not.
892    const llvm::Type *IdxType = llvm::IntegerType::get(CGF.LLVMPointerWidth);
893    if (IdxExp->getType()->isSignedIntegerType())
894      Idx = Builder.CreateSExt(Idx, IdxType, "idx.ext");
895    else
896      Idx = Builder.CreateZExt(Idx, IdxType, "idx.ext");
897  }
898
899  // Explicitly handle GNU void* and function pointer arithmetic
900  // extensions. The GNU void* casts amount to no-ops since our void*
901  // type is i8*, but this is future proof.
902  const QualType ElementType = PT->getPointeeType();
903  if (ElementType->isVoidType() || ElementType->isFunctionType()) {
904    const llvm::Type *i8Ty = llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
905    Value *Casted = Builder.CreateBitCast(Ptr, i8Ty);
906    Value *Res = Builder.CreateGEP(Casted, Idx, "sub.ptr");
907    return Builder.CreateBitCast(Res, Ptr->getType());
908  }
909
910  return Builder.CreateGEP(Ptr, Idx, "add.ptr");
911}
912
913Value *ScalarExprEmitter::EmitSub(const BinOpInfo &Ops) {
914  if (!isa<llvm::PointerType>(Ops.LHS->getType()))
915    return Builder.CreateSub(Ops.LHS, Ops.RHS, "sub");
916
917  const QualType LHSType = Ops.E->getLHS()->getType();
918  const QualType LHSElementType = LHSType->getAsPointerType()->getPointeeType();
919  if (!isa<llvm::PointerType>(Ops.RHS->getType())) {
920    // pointer - int
921    Value *Idx = Ops.RHS;
922    unsigned Width = cast<llvm::IntegerType>(Idx->getType())->getBitWidth();
923    if (Width < CGF.LLVMPointerWidth) {
924      // Zero or sign extend the pointer value based on whether the index is
925      // signed or not.
926      const llvm::Type *IdxType = llvm::IntegerType::get(CGF.LLVMPointerWidth);
927      if (Ops.E->getRHS()->getType()->isSignedIntegerType())
928        Idx = Builder.CreateSExt(Idx, IdxType, "idx.ext");
929      else
930        Idx = Builder.CreateZExt(Idx, IdxType, "idx.ext");
931    }
932    Idx = Builder.CreateNeg(Idx, "sub.ptr.neg");
933
934    // FIXME: The pointer could point to a VLA.
935
936    // Explicitly handle GNU void* and function pointer arithmetic
937    // extensions. The GNU void* casts amount to no-ops since our
938    // void* type is i8*, but this is future proof.
939    if (LHSElementType->isVoidType() || LHSElementType->isFunctionType()) {
940      const llvm::Type *i8Ty = llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
941      Value *LHSCasted = Builder.CreateBitCast(Ops.LHS, i8Ty);
942      Value *Res = Builder.CreateGEP(LHSCasted, Idx, "sub.ptr");
943      return Builder.CreateBitCast(Res, Ops.LHS->getType());
944    }
945
946    return Builder.CreateGEP(Ops.LHS, Idx, "sub.ptr");
947  } else {
948    // pointer - pointer
949    Value *LHS = Ops.LHS;
950    Value *RHS = Ops.RHS;
951
952    uint64_t ElementSize;
953
954    // Handle GCC extension for pointer arithmetic on void* types.
955    if (LHSElementType->isVoidType()) {
956      ElementSize = 1;
957    } else {
958      ElementSize = CGF.getContext().getTypeSize(LHSElementType) / 8;
959    }
960
961    const llvm::Type *ResultType = ConvertType(Ops.Ty);
962    LHS = Builder.CreatePtrToInt(LHS, ResultType, "sub.ptr.lhs.cast");
963    RHS = Builder.CreatePtrToInt(RHS, ResultType, "sub.ptr.rhs.cast");
964    Value *BytesBetween = Builder.CreateSub(LHS, RHS, "sub.ptr.sub");
965
966    // HACK: LLVM doesn't have an divide instruction that 'knows' there is no
967    // remainder.  As such, we handle common power-of-two cases here to generate
968    // better code. See PR2247.
969    if (llvm::isPowerOf2_64(ElementSize)) {
970      Value *ShAmt =
971        llvm::ConstantInt::get(ResultType, llvm::Log2_64(ElementSize));
972      return Builder.CreateAShr(BytesBetween, ShAmt, "sub.ptr.shr");
973    }
974
975    // Otherwise, do a full sdiv.
976    Value *BytesPerElt = llvm::ConstantInt::get(ResultType, ElementSize);
977    return Builder.CreateSDiv(BytesBetween, BytesPerElt, "sub.ptr.div");
978  }
979}
980
981Value *ScalarExprEmitter::EmitShl(const BinOpInfo &Ops) {
982  // LLVM requires the LHS and RHS to be the same type: promote or truncate the
983  // RHS to the same size as the LHS.
984  Value *RHS = Ops.RHS;
985  if (Ops.LHS->getType() != RHS->getType())
986    RHS = Builder.CreateIntCast(RHS, Ops.LHS->getType(), false, "sh_prom");
987
988  return Builder.CreateShl(Ops.LHS, RHS, "shl");
989}
990
991Value *ScalarExprEmitter::EmitShr(const BinOpInfo &Ops) {
992  // LLVM requires the LHS and RHS to be the same type: promote or truncate the
993  // RHS to the same size as the LHS.
994  Value *RHS = Ops.RHS;
995  if (Ops.LHS->getType() != RHS->getType())
996    RHS = Builder.CreateIntCast(RHS, Ops.LHS->getType(), false, "sh_prom");
997
998  if (Ops.Ty->isUnsignedIntegerType())
999    return Builder.CreateLShr(Ops.LHS, RHS, "shr");
1000  return Builder.CreateAShr(Ops.LHS, RHS, "shr");
1001}
1002
1003Value *ScalarExprEmitter::EmitCompare(const BinaryOperator *E,unsigned UICmpOpc,
1004                                      unsigned SICmpOpc, unsigned FCmpOpc) {
1005  Value *Result;
1006  QualType LHSTy = E->getLHS()->getType();
1007  if (!LHSTy->isAnyComplexType() && !LHSTy->isVectorType()) {
1008    Value *LHS = Visit(E->getLHS());
1009    Value *RHS = Visit(E->getRHS());
1010
1011    if (LHS->getType()->isFloatingPoint()) {
1012      Result = Builder.CreateFCmp((llvm::CmpInst::Predicate)FCmpOpc,
1013                                  LHS, RHS, "cmp");
1014    } else if (LHSTy->isSignedIntegerType()) {
1015      Result = Builder.CreateICmp((llvm::ICmpInst::Predicate)SICmpOpc,
1016                                  LHS, RHS, "cmp");
1017    } else {
1018      // Unsigned integers and pointers.
1019      Result = Builder.CreateICmp((llvm::ICmpInst::Predicate)UICmpOpc,
1020                                  LHS, RHS, "cmp");
1021    }
1022  } else if (LHSTy->isVectorType()) {
1023    Value *LHS = Visit(E->getLHS());
1024    Value *RHS = Visit(E->getRHS());
1025
1026    if (LHS->getType()->isFPOrFPVector()) {
1027      Result = Builder.CreateVFCmp((llvm::CmpInst::Predicate)FCmpOpc,
1028                                  LHS, RHS, "cmp");
1029    } else if (LHSTy->isUnsignedIntegerType()) {
1030      Result = Builder.CreateVICmp((llvm::CmpInst::Predicate)UICmpOpc,
1031                                  LHS, RHS, "cmp");
1032    } else {
1033      // Signed integers and pointers.
1034      Result = Builder.CreateVICmp((llvm::CmpInst::Predicate)SICmpOpc,
1035                                  LHS, RHS, "cmp");
1036    }
1037    return Result;
1038  } else {
1039    // Complex Comparison: can only be an equality comparison.
1040    CodeGenFunction::ComplexPairTy LHS = CGF.EmitComplexExpr(E->getLHS());
1041    CodeGenFunction::ComplexPairTy RHS = CGF.EmitComplexExpr(E->getRHS());
1042
1043    QualType CETy = LHSTy->getAsComplexType()->getElementType();
1044
1045    Value *ResultR, *ResultI;
1046    if (CETy->isRealFloatingType()) {
1047      ResultR = Builder.CreateFCmp((llvm::FCmpInst::Predicate)FCmpOpc,
1048                                   LHS.first, RHS.first, "cmp.r");
1049      ResultI = Builder.CreateFCmp((llvm::FCmpInst::Predicate)FCmpOpc,
1050                                   LHS.second, RHS.second, "cmp.i");
1051    } else {
1052      // Complex comparisons can only be equality comparisons.  As such, signed
1053      // and unsigned opcodes are the same.
1054      ResultR = Builder.CreateICmp((llvm::ICmpInst::Predicate)UICmpOpc,
1055                                   LHS.first, RHS.first, "cmp.r");
1056      ResultI = Builder.CreateICmp((llvm::ICmpInst::Predicate)UICmpOpc,
1057                                   LHS.second, RHS.second, "cmp.i");
1058    }
1059
1060    if (E->getOpcode() == BinaryOperator::EQ) {
1061      Result = Builder.CreateAnd(ResultR, ResultI, "and.ri");
1062    } else {
1063      assert(E->getOpcode() == BinaryOperator::NE &&
1064             "Complex comparison other than == or != ?");
1065      Result = Builder.CreateOr(ResultR, ResultI, "or.ri");
1066    }
1067  }
1068
1069  return EmitScalarConversion(Result, CGF.getContext().BoolTy, E->getType());
1070}
1071
1072Value *ScalarExprEmitter::VisitBinAssign(const BinaryOperator *E) {
1073  LValue LHS = EmitLValue(E->getLHS());
1074  Value *RHS = Visit(E->getRHS());
1075
1076  // Store the value into the LHS.  Bit-fields are handled specially
1077  // because the result is altered by the store, i.e., [C99 6.5.16p1]
1078  // 'An assignment expression has the value of the left operand after
1079  // the assignment...'.
1080  // FIXME: Volatility!
1081  if (LHS.isBitfield())
1082    CGF.EmitStoreThroughBitfieldLValue(RValue::get(RHS), LHS, E->getType(),
1083                                       &RHS);
1084  else
1085    CGF.EmitStoreThroughLValue(RValue::get(RHS), LHS, E->getType());
1086
1087  // Return the RHS.
1088  return RHS;
1089}
1090
1091Value *ScalarExprEmitter::VisitBinLAnd(const BinaryOperator *E) {
1092  // If we have 0 && RHS, see if we can elide RHS, if so, just return 0.
1093  // If we have 1 && X, just emit X without inserting the control flow.
1094  if (int Cond = CGF.ConstantFoldsToSimpleInteger(E->getLHS())) {
1095    if (Cond == 1) { // If we have 1 && X, just emit X.
1096      Value *RHSCond = CGF.EvaluateExprAsBool(E->getRHS());
1097      // ZExt result to int.
1098      return Builder.CreateZExt(RHSCond, CGF.LLVMIntTy, "land.ext");
1099    }
1100
1101    // 0 && RHS: If it is safe, just elide the RHS, and return 0.
1102    if (!CGF.ContainsLabel(E->getRHS()))
1103      return llvm::Constant::getNullValue(CGF.LLVMIntTy);
1104  }
1105
1106  llvm::BasicBlock *ContBlock = CGF.createBasicBlock("land.end");
1107  llvm::BasicBlock *RHSBlock  = CGF.createBasicBlock("land.rhs");
1108
1109  // Branch on the LHS first.  If it is false, go to the failure (cont) block.
1110  CGF.EmitBranchOnBoolExpr(E->getLHS(), RHSBlock, ContBlock);
1111
1112  // Any edges into the ContBlock are now from an (indeterminate number of)
1113  // edges from this first condition.  All of these values will be false.  Start
1114  // setting up the PHI node in the Cont Block for this.
1115  llvm::PHINode *PN = llvm::PHINode::Create(llvm::Type::Int1Ty, "", ContBlock);
1116  PN->reserveOperandSpace(2);  // Normal case, two inputs.
1117  for (llvm::pred_iterator PI = pred_begin(ContBlock), PE = pred_end(ContBlock);
1118       PI != PE; ++PI)
1119    PN->addIncoming(llvm::ConstantInt::getFalse(), *PI);
1120
1121  CGF.EmitBlock(RHSBlock);
1122  Value *RHSCond = CGF.EvaluateExprAsBool(E->getRHS());
1123
1124  // Reaquire the RHS block, as there may be subblocks inserted.
1125  RHSBlock = Builder.GetInsertBlock();
1126
1127  // Emit an unconditional branch from this block to ContBlock.  Insert an entry
1128  // into the phi node for the edge with the value of RHSCond.
1129  CGF.EmitBlock(ContBlock);
1130  PN->addIncoming(RHSCond, RHSBlock);
1131
1132  // ZExt result to int.
1133  return Builder.CreateZExt(PN, CGF.LLVMIntTy, "land.ext");
1134}
1135
1136Value *ScalarExprEmitter::VisitBinLOr(const BinaryOperator *E) {
1137  // If we have 1 || RHS, see if we can elide RHS, if so, just return 1.
1138  // If we have 0 || X, just emit X without inserting the control flow.
1139  if (int Cond = CGF.ConstantFoldsToSimpleInteger(E->getLHS())) {
1140    if (Cond == -1) { // If we have 0 || X, just emit X.
1141      Value *RHSCond = CGF.EvaluateExprAsBool(E->getRHS());
1142      // ZExt result to int.
1143      return Builder.CreateZExt(RHSCond, CGF.LLVMIntTy, "lor.ext");
1144    }
1145
1146    // 1 || RHS: If it is safe, just elide the RHS, and return 1.
1147    if (!CGF.ContainsLabel(E->getRHS()))
1148      return llvm::ConstantInt::get(CGF.LLVMIntTy, 1);
1149  }
1150
1151  llvm::BasicBlock *ContBlock = CGF.createBasicBlock("lor.end");
1152  llvm::BasicBlock *RHSBlock = CGF.createBasicBlock("lor.rhs");
1153
1154  // Branch on the LHS first.  If it is true, go to the success (cont) block.
1155  CGF.EmitBranchOnBoolExpr(E->getLHS(), ContBlock, RHSBlock);
1156
1157  // Any edges into the ContBlock are now from an (indeterminate number of)
1158  // edges from this first condition.  All of these values will be true.  Start
1159  // setting up the PHI node in the Cont Block for this.
1160  llvm::PHINode *PN = llvm::PHINode::Create(llvm::Type::Int1Ty, "", ContBlock);
1161  PN->reserveOperandSpace(2);  // Normal case, two inputs.
1162  for (llvm::pred_iterator PI = pred_begin(ContBlock), PE = pred_end(ContBlock);
1163       PI != PE; ++PI)
1164    PN->addIncoming(llvm::ConstantInt::getTrue(), *PI);
1165
1166  // Emit the RHS condition as a bool value.
1167  CGF.EmitBlock(RHSBlock);
1168  Value *RHSCond = CGF.EvaluateExprAsBool(E->getRHS());
1169
1170  // Reaquire the RHS block, as there may be subblocks inserted.
1171  RHSBlock = Builder.GetInsertBlock();
1172
1173  // Emit an unconditional branch from this block to ContBlock.  Insert an entry
1174  // into the phi node for the edge with the value of RHSCond.
1175  CGF.EmitBlock(ContBlock);
1176  PN->addIncoming(RHSCond, RHSBlock);
1177
1178  // ZExt result to int.
1179  return Builder.CreateZExt(PN, CGF.LLVMIntTy, "lor.ext");
1180}
1181
1182Value *ScalarExprEmitter::VisitBinComma(const BinaryOperator *E) {
1183  CGF.EmitStmt(E->getLHS());
1184  CGF.EnsureInsertPoint();
1185  return Visit(E->getRHS());
1186}
1187
1188//===----------------------------------------------------------------------===//
1189//                             Other Operators
1190//===----------------------------------------------------------------------===//
1191
1192/// isCheapEnoughToEvaluateUnconditionally - Return true if the specified
1193/// expression is cheap enough and side-effect-free enough to evaluate
1194/// unconditionally instead of conditionally.  This is used to convert control
1195/// flow into selects in some cases.
1196static bool isCheapEnoughToEvaluateUnconditionally(const Expr *E) {
1197  if (const ParenExpr *PE = dyn_cast<ParenExpr>(E))
1198    return isCheapEnoughToEvaluateUnconditionally(PE->getSubExpr());
1199
1200  // TODO: Allow anything we can constant fold to an integer or fp constant.
1201  if (isa<IntegerLiteral>(E) || isa<CharacterLiteral>(E) ||
1202      isa<FloatingLiteral>(E))
1203    return true;
1204
1205  // Non-volatile automatic variables too, to get "cond ? X : Y" where
1206  // X and Y are local variables.
1207  if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
1208    if (const VarDecl *VD = dyn_cast<VarDecl>(DRE->getDecl()))
1209      if (VD->hasLocalStorage() && !VD->getType().isVolatileQualified())
1210        return true;
1211
1212  return false;
1213}
1214
1215
1216Value *ScalarExprEmitter::
1217VisitConditionalOperator(const ConditionalOperator *E) {
1218  // If the condition constant folds and can be elided, try to avoid emitting
1219  // the condition and the dead arm.
1220  if (int Cond = CGF.ConstantFoldsToSimpleInteger(E->getCond())){
1221    Expr *Live = E->getLHS(), *Dead = E->getRHS();
1222    if (Cond == -1)
1223      std::swap(Live, Dead);
1224
1225    // If the dead side doesn't have labels we need, and if the Live side isn't
1226    // the gnu missing ?: extension (which we could handle, but don't bother
1227    // to), just emit the Live part.
1228    if ((!Dead || !CGF.ContainsLabel(Dead)) &&  // No labels in dead part
1229        Live)                                   // Live part isn't missing.
1230      return Visit(Live);
1231  }
1232
1233
1234  // If this is a really simple expression (like x ? 4 : 5), emit this as a
1235  // select instead of as control flow.  We can only do this if it is cheap and
1236  // safe to evaluate the LHS and RHS unconditionally.
1237  if (E->getLHS() && isCheapEnoughToEvaluateUnconditionally(E->getLHS()) &&
1238      isCheapEnoughToEvaluateUnconditionally(E->getRHS())) {
1239    llvm::Value *CondV = CGF.EvaluateExprAsBool(E->getCond());
1240    llvm::Value *LHS = Visit(E->getLHS());
1241    llvm::Value *RHS = Visit(E->getRHS());
1242    return Builder.CreateSelect(CondV, LHS, RHS, "cond");
1243  }
1244
1245
1246  llvm::BasicBlock *LHSBlock = CGF.createBasicBlock("cond.true");
1247  llvm::BasicBlock *RHSBlock = CGF.createBasicBlock("cond.false");
1248  llvm::BasicBlock *ContBlock = CGF.createBasicBlock("cond.end");
1249  Value *CondVal = 0;
1250
1251  // If we have the GNU missing condition extension, evaluate the conditional
1252  // and then convert it to bool the hard way.  We do this explicitly
1253  // because we need the unconverted value for the missing middle value of
1254  // the ?:.
1255  if (E->getLHS() == 0) {
1256    CondVal = CGF.EmitScalarExpr(E->getCond());
1257    Value *CondBoolVal =
1258      CGF.EmitScalarConversion(CondVal, E->getCond()->getType(),
1259                               CGF.getContext().BoolTy);
1260    Builder.CreateCondBr(CondBoolVal, LHSBlock, RHSBlock);
1261  } else {
1262    // Otherwise, just use EmitBranchOnBoolExpr to get small and simple code for
1263    // the branch on bool.
1264    CGF.EmitBranchOnBoolExpr(E->getCond(), LHSBlock, RHSBlock);
1265  }
1266
1267  CGF.EmitBlock(LHSBlock);
1268
1269  // Handle the GNU extension for missing LHS.
1270  Value *LHS;
1271  if (E->getLHS())
1272    LHS = Visit(E->getLHS());
1273  else    // Perform promotions, to handle cases like "short ?: int"
1274    LHS = EmitScalarConversion(CondVal, E->getCond()->getType(), E->getType());
1275
1276  LHSBlock = Builder.GetInsertBlock();
1277  CGF.EmitBranch(ContBlock);
1278
1279  CGF.EmitBlock(RHSBlock);
1280
1281  Value *RHS = Visit(E->getRHS());
1282  RHSBlock = Builder.GetInsertBlock();
1283  CGF.EmitBranch(ContBlock);
1284
1285  CGF.EmitBlock(ContBlock);
1286
1287  if (!LHS || !RHS) {
1288    assert(E->getType()->isVoidType() && "Non-void value should have a value");
1289    return 0;
1290  }
1291
1292  // Create a PHI node for the real part.
1293  llvm::PHINode *PN = Builder.CreatePHI(LHS->getType(), "cond");
1294  PN->reserveOperandSpace(2);
1295  PN->addIncoming(LHS, LHSBlock);
1296  PN->addIncoming(RHS, RHSBlock);
1297  return PN;
1298}
1299
1300Value *ScalarExprEmitter::VisitChooseExpr(ChooseExpr *E) {
1301  // Emit the LHS or RHS as appropriate.
1302  return
1303    Visit(E->isConditionTrue(CGF.getContext()) ? E->getLHS() : E->getRHS());
1304}
1305
1306Value *ScalarExprEmitter::VisitOverloadExpr(OverloadExpr *E) {
1307  return CGF.EmitCallExpr(E->getFn(), E->arg_begin(),
1308                          E->arg_end(CGF.getContext())).getScalarVal();
1309}
1310
1311Value *ScalarExprEmitter::VisitVAArgExpr(VAArgExpr *VE) {
1312  llvm::Value *ArgValue = CGF.EmitVAListRef(VE->getSubExpr());
1313
1314  llvm::Value *ArgPtr = CGF.EmitVAArg(ArgValue, VE->getType());
1315
1316  // If EmitVAArg fails, we fall back to the LLVM instruction.
1317  if (!ArgPtr)
1318    return Builder.CreateVAArg(ArgValue, ConvertType(VE->getType()));
1319
1320  // FIXME: volatile?
1321  return Builder.CreateLoad(ArgPtr);
1322}
1323
1324Value *ScalarExprEmitter::VisitObjCEncodeExpr(const ObjCEncodeExpr *E) {
1325  std::string str;
1326  CGF.getContext().getObjCEncodingForType(E->getEncodedType(), str);
1327
1328  llvm::Constant *C = llvm::ConstantArray::get(str);
1329  C = new llvm::GlobalVariable(C->getType(), true,
1330                               llvm::GlobalValue::InternalLinkage,
1331                               C, ".str", &CGF.CGM.getModule());
1332  llvm::Constant *Zero = llvm::Constant::getNullValue(llvm::Type::Int32Ty);
1333  llvm::Constant *Zeros[] = { Zero, Zero };
1334  C = llvm::ConstantExpr::getGetElementPtr(C, Zeros, 2);
1335
1336  return C;
1337}
1338
1339//===----------------------------------------------------------------------===//
1340//                         Entry Point into this File
1341//===----------------------------------------------------------------------===//
1342
1343/// EmitComplexExpr - Emit the computation of the specified expression of
1344/// complex type, ignoring the result.
1345Value *CodeGenFunction::EmitScalarExpr(const Expr *E) {
1346  assert(E && !hasAggregateLLVMType(E->getType()) &&
1347         "Invalid scalar expression to emit");
1348
1349  return ScalarExprEmitter(*this).Visit(const_cast<Expr*>(E));
1350}
1351
1352/// EmitScalarConversion - Emit a conversion from the specified type to the
1353/// specified destination type, both of which are LLVM scalar types.
1354Value *CodeGenFunction::EmitScalarConversion(Value *Src, QualType SrcTy,
1355                                             QualType DstTy) {
1356  assert(!hasAggregateLLVMType(SrcTy) && !hasAggregateLLVMType(DstTy) &&
1357         "Invalid scalar expression to emit");
1358  return ScalarExprEmitter(*this).EmitScalarConversion(Src, SrcTy, DstTy);
1359}
1360
1361/// EmitComplexToScalarConversion - Emit a conversion from the specified
1362/// complex type to the specified destination type, where the destination
1363/// type is an LLVM scalar type.
1364Value *CodeGenFunction::EmitComplexToScalarConversion(ComplexPairTy Src,
1365                                                      QualType SrcTy,
1366                                                      QualType DstTy) {
1367  assert(SrcTy->isAnyComplexType() && !hasAggregateLLVMType(DstTy) &&
1368         "Invalid complex -> scalar conversion");
1369  return ScalarExprEmitter(*this).EmitComplexToScalarConversion(Src, SrcTy,
1370                                                                DstTy);
1371}
1372
1373Value *CodeGenFunction::EmitShuffleVector(Value* V1, Value *V2, ...) {
1374  assert(V1->getType() == V2->getType() &&
1375         "Vector operands must be of the same type");
1376  unsigned NumElements =
1377    cast<llvm::VectorType>(V1->getType())->getNumElements();
1378
1379  va_list va;
1380  va_start(va, V2);
1381
1382  llvm::SmallVector<llvm::Constant*, 16> Args;
1383  for (unsigned i = 0; i < NumElements; i++) {
1384    int n = va_arg(va, int);
1385    assert(n >= 0 && n < (int)NumElements * 2 &&
1386           "Vector shuffle index out of bounds!");
1387    Args.push_back(llvm::ConstantInt::get(llvm::Type::Int32Ty, n));
1388  }
1389
1390  const char *Name = va_arg(va, const char *);
1391  va_end(va);
1392
1393  llvm::Constant *Mask = llvm::ConstantVector::get(&Args[0], NumElements);
1394
1395  return Builder.CreateShuffleVector(V1, V2, Mask, Name);
1396}
1397
1398llvm::Value *CodeGenFunction::EmitVector(llvm::Value * const *Vals,
1399                                         unsigned NumVals, bool isSplat) {
1400  llvm::Value *Vec
1401    = llvm::UndefValue::get(llvm::VectorType::get(Vals[0]->getType(), NumVals));
1402
1403  for (unsigned i = 0, e = NumVals; i != e; ++i) {
1404    llvm::Value *Val = isSplat ? Vals[0] : Vals[i];
1405    llvm::Value *Idx = llvm::ConstantInt::get(llvm::Type::Int32Ty, i);
1406    Vec = Builder.CreateInsertElement(Vec, Val, Idx, "tmp");
1407  }
1408
1409  return Vec;
1410}
1411