CGExprScalar.cpp revision a99038c0757a836c6faeeddaa5dfd249b32f6e9e 
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/RecordLayout.h"
19#include "clang/AST/StmtVisitor.h"
20#include "clang/Basic/TargetInfo.h"
21#include "llvm/Constants.h"
22#include "llvm/Function.h"
23#include "llvm/GlobalVariable.h"
24#include "llvm/Intrinsics.h"
25#include "llvm/Support/Compiler.h"
26#include "llvm/Support/CFG.h"
27#include "llvm/Target/TargetData.h"
28#include <cstdarg>
29
30using namespace clang;
31using namespace CodeGen;
32using llvm::Value;
33
34//===----------------------------------------------------------------------===//
35//                         Scalar Expression Emitter
36//===----------------------------------------------------------------------===//
37
38struct BinOpInfo {
39  Value *LHS;
40  Value *RHS;
41  QualType Ty;  // Computation Type.
42  const BinaryOperator *E;
43};
44
45namespace {
46class VISIBILITY_HIDDEN ScalarExprEmitter
47  : public StmtVisitor<ScalarExprEmitter, Value*> {
48  CodeGenFunction &CGF;
49  CGBuilderTy &Builder;
50
51public:
52
53  ScalarExprEmitter(CodeGenFunction &cgf) : CGF(cgf),
54    Builder(CGF.Builder) {
55  }
56
57  //===--------------------------------------------------------------------===//
58  //                               Utilities
59  //===--------------------------------------------------------------------===//
60
61  const llvm::Type *ConvertType(QualType T) { return CGF.ConvertType(T); }
62  LValue EmitLValue(const Expr *E) { return CGF.EmitLValue(E); }
63
64  Value *EmitLoadOfLValue(LValue LV, QualType T) {
65    return CGF.EmitLoadOfLValue(LV, T).getScalarVal();
66  }
67
68  /// EmitLoadOfLValue - Given an expression with complex type that represents a
69  /// value l-value, this method emits the address of the l-value, then loads
70  /// and returns the result.
71  Value *EmitLoadOfLValue(const Expr *E) {
72    // FIXME: Volatile
73    return EmitLoadOfLValue(EmitLValue(E), E->getType());
74  }
75
76  /// EmitConversionToBool - Convert the specified expression value to a
77  /// boolean (i1) truth value.  This is equivalent to "Val != 0".
78  Value *EmitConversionToBool(Value *Src, QualType DstTy);
79
80  /// EmitScalarConversion - Emit a conversion from the specified type to the
81  /// specified destination type, both of which are LLVM scalar types.
82  Value *EmitScalarConversion(Value *Src, QualType SrcTy, QualType DstTy);
83
84  /// EmitComplexToScalarConversion - Emit a conversion from the specified
85  /// complex type to the specified destination type, where the destination
86  /// type is an LLVM scalar type.
87  Value *EmitComplexToScalarConversion(CodeGenFunction::ComplexPairTy Src,
88                                       QualType SrcTy, QualType DstTy);
89
90  //===--------------------------------------------------------------------===//
91  //                            Visitor Methods
92  //===--------------------------------------------------------------------===//
93
94  Value *VisitStmt(Stmt *S) {
95    S->dump(CGF.getContext().getSourceManager());
96    assert(0 && "Stmt can't have complex result type!");
97    return 0;
98  }
99  Value *VisitExpr(Expr *S);
100  Value *VisitParenExpr(ParenExpr *PE) { return Visit(PE->getSubExpr()); }
101
102  // Leaves.
103  Value *VisitIntegerLiteral(const IntegerLiteral *E) {
104    return llvm::ConstantInt::get(E->getValue());
105  }
106  Value *VisitFloatingLiteral(const FloatingLiteral *E) {
107    return llvm::ConstantFP::get(E->getValue());
108  }
109  Value *VisitCharacterLiteral(const CharacterLiteral *E) {
110    return llvm::ConstantInt::get(ConvertType(E->getType()), E->getValue());
111  }
112  Value *VisitCXXBoolLiteralExpr(const CXXBoolLiteralExpr *E) {
113    return llvm::ConstantInt::get(ConvertType(E->getType()), E->getValue());
114  }
115  Value *VisitCXXZeroInitValueExpr(const CXXZeroInitValueExpr *E) {
116    return llvm::Constant::getNullValue(ConvertType(E->getType()));
117  }
118  Value *VisitGNUNullExpr(const GNUNullExpr *E) {
119    return llvm::Constant::getNullValue(ConvertType(E->getType()));
120  }
121  Value *VisitTypesCompatibleExpr(const TypesCompatibleExpr *E) {
122    return llvm::ConstantInt::get(ConvertType(E->getType()),
123                                  CGF.getContext().typesAreCompatible(
124                                    E->getArgType1(), E->getArgType2()));
125  }
126  Value *VisitSizeOfAlignOfExpr(const SizeOfAlignOfExpr *E);
127  Value *VisitAddrLabelExpr(const AddrLabelExpr *E) {
128    llvm::Value *V =
129      llvm::ConstantInt::get(llvm::Type::Int32Ty,
130                             CGF.GetIDForAddrOfLabel(E->getLabel()));
131
132    return Builder.CreateIntToPtr(V, ConvertType(E->getType()));
133  }
134
135  // l-values.
136  Value *VisitDeclRefExpr(DeclRefExpr *E) {
137    if (const EnumConstantDecl *EC = dyn_cast<EnumConstantDecl>(E->getDecl()))
138      return llvm::ConstantInt::get(EC->getInitVal());
139    return EmitLoadOfLValue(E);
140  }
141  Value *VisitObjCSelectorExpr(ObjCSelectorExpr *E) {
142    return CGF.EmitObjCSelectorExpr(E);
143  }
144  Value *VisitObjCProtocolExpr(ObjCProtocolExpr *E) {
145    return CGF.EmitObjCProtocolExpr(E);
146  }
147  Value *VisitObjCIvarRefExpr(ObjCIvarRefExpr *E) {
148    return EmitLoadOfLValue(E);
149  }
150  Value *VisitObjCPropertyRefExpr(ObjCPropertyRefExpr *E) {
151    return EmitLoadOfLValue(E);
152  }
153  Value *VisitObjCKVCRefExpr(ObjCKVCRefExpr *E) {
154    return EmitLoadOfLValue(E);
155  }
156  Value *VisitObjCMessageExpr(ObjCMessageExpr *E) {
157    return CGF.EmitObjCMessageExpr(E).getScalarVal();
158  }
159
160  Value *VisitArraySubscriptExpr(ArraySubscriptExpr *E);
161  Value *VisitShuffleVectorExpr(ShuffleVectorExpr *E);
162  Value *VisitMemberExpr(Expr *E)           { return EmitLoadOfLValue(E); }
163  Value *VisitExtVectorElementExpr(Expr *E) { return EmitLoadOfLValue(E); }
164  Value *VisitCompoundLiteralExpr(CompoundLiteralExpr *E) {
165    return EmitLoadOfLValue(E);
166  }
167  Value *VisitStringLiteral(Expr *E)  { return EmitLValue(E).getAddress(); }
168  Value *VisitObjCEncodeExpr(const ObjCEncodeExpr *E) {
169     return EmitLValue(E).getAddress();
170  }
171
172  Value *VisitPredefinedExpr(Expr *E) { return EmitLValue(E).getAddress(); }
173
174  Value *VisitInitListExpr(InitListExpr *E) {
175    unsigned NumInitElements = E->getNumInits();
176
177    if (E->hadArrayRangeDesignator()) {
178      CGF.ErrorUnsupported(E, "GNU array range designator extension");
179    }
180
181    const llvm::VectorType *VType =
182      dyn_cast<llvm::VectorType>(ConvertType(E->getType()));
183
184    // We have a scalar in braces. Just use the first element.
185    if (!VType)
186      return Visit(E->getInit(0));
187
188    unsigned NumVectorElements = VType->getNumElements();
189    const llvm::Type *ElementType = VType->getElementType();
190
191    // Emit individual vector element stores.
192    llvm::Value *V = llvm::UndefValue::get(VType);
193
194    // Emit initializers
195    unsigned i;
196    for (i = 0; i < NumInitElements; ++i) {
197      Value *NewV = Visit(E->getInit(i));
198      Value *Idx = llvm::ConstantInt::get(llvm::Type::Int32Ty, i);
199      V = Builder.CreateInsertElement(V, NewV, Idx);
200    }
201
202    // Emit remaining default initializers
203    for (/* Do not initialize i*/; i < NumVectorElements; ++i) {
204      Value *Idx = llvm::ConstantInt::get(llvm::Type::Int32Ty, i);
205      llvm::Value *NewV = llvm::Constant::getNullValue(ElementType);
206      V = Builder.CreateInsertElement(V, NewV, Idx);
207    }
208
209    return V;
210  }
211
212  Value *VisitImplicitValueInitExpr(const ImplicitValueInitExpr *E) {
213    return llvm::Constant::getNullValue(ConvertType(E->getType()));
214  }
215  Value *VisitImplicitCastExpr(const ImplicitCastExpr *E);
216  Value *VisitCastExpr(const CastExpr *E) {
217    return EmitCastExpr(E->getSubExpr(), E->getType());
218  }
219  Value *EmitCastExpr(const Expr *E, QualType T);
220
221  Value *VisitCallExpr(const CallExpr *E) {
222    return CGF.EmitCallExpr(E).getScalarVal();
223  }
224
225  Value *VisitStmtExpr(const StmtExpr *E);
226
227  Value *VisitBlockDeclRefExpr(const BlockDeclRefExpr *E);
228
229  // Unary Operators.
230  Value *VisitPrePostIncDec(const UnaryOperator *E, bool isInc, bool isPre);
231  Value *VisitUnaryPostDec(const UnaryOperator *E) {
232    return VisitPrePostIncDec(E, false, false);
233  }
234  Value *VisitUnaryPostInc(const UnaryOperator *E) {
235    return VisitPrePostIncDec(E, true, false);
236  }
237  Value *VisitUnaryPreDec(const UnaryOperator *E) {
238    return VisitPrePostIncDec(E, false, true);
239  }
240  Value *VisitUnaryPreInc(const UnaryOperator *E) {
241    return VisitPrePostIncDec(E, true, true);
242  }
243  Value *VisitUnaryAddrOf(const UnaryOperator *E) {
244    return EmitLValue(E->getSubExpr()).getAddress();
245  }
246  Value *VisitUnaryDeref(const Expr *E) { return EmitLoadOfLValue(E); }
247  Value *VisitUnaryPlus(const UnaryOperator *E) {
248    return Visit(E->getSubExpr());
249  }
250  Value *VisitUnaryMinus    (const UnaryOperator *E);
251  Value *VisitUnaryNot      (const UnaryOperator *E);
252  Value *VisitUnaryLNot     (const UnaryOperator *E);
253  Value *VisitUnaryReal     (const UnaryOperator *E);
254  Value *VisitUnaryImag     (const UnaryOperator *E);
255  Value *VisitUnaryExtension(const UnaryOperator *E) {
256    return Visit(E->getSubExpr());
257  }
258  Value *VisitUnaryOffsetOf(const UnaryOperator *E);
259  Value *VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) {
260    return Visit(DAE->getExpr());
261  }
262
263  // Binary Operators.
264  Value *EmitMul(const BinOpInfo &Ops) {
265    return Builder.CreateMul(Ops.LHS, Ops.RHS, "mul");
266  }
267  Value *EmitDiv(const BinOpInfo &Ops);
268  Value *EmitRem(const BinOpInfo &Ops);
269  Value *EmitAdd(const BinOpInfo &Ops);
270  Value *EmitSub(const BinOpInfo &Ops);
271  Value *EmitShl(const BinOpInfo &Ops);
272  Value *EmitShr(const BinOpInfo &Ops);
273  Value *EmitAnd(const BinOpInfo &Ops) {
274    return Builder.CreateAnd(Ops.LHS, Ops.RHS, "and");
275  }
276  Value *EmitXor(const BinOpInfo &Ops) {
277    return Builder.CreateXor(Ops.LHS, Ops.RHS, "xor");
278  }
279  Value *EmitOr (const BinOpInfo &Ops) {
280    return Builder.CreateOr(Ops.LHS, Ops.RHS, "or");
281  }
282
283  BinOpInfo EmitBinOps(const BinaryOperator *E);
284  Value *EmitCompoundAssign(const CompoundAssignOperator *E,
285                            Value *(ScalarExprEmitter::*F)(const BinOpInfo &));
286
287  // Binary operators and binary compound assignment operators.
288#define HANDLEBINOP(OP) \
289  Value *VisitBin ## OP(const BinaryOperator *E) {                         \
290    return Emit ## OP(EmitBinOps(E));                                      \
291  }                                                                        \
292  Value *VisitBin ## OP ## Assign(const CompoundAssignOperator *E) {       \
293    return EmitCompoundAssign(E, &ScalarExprEmitter::Emit ## OP);          \
294  }
295  HANDLEBINOP(Mul);
296  HANDLEBINOP(Div);
297  HANDLEBINOP(Rem);
298  HANDLEBINOP(Add);
299  HANDLEBINOP(Sub);
300  HANDLEBINOP(Shl);
301  HANDLEBINOP(Shr);
302  HANDLEBINOP(And);
303  HANDLEBINOP(Xor);
304  HANDLEBINOP(Or);
305#undef HANDLEBINOP
306
307  // Comparisons.
308  Value *EmitCompare(const BinaryOperator *E, unsigned UICmpOpc,
309                     unsigned SICmpOpc, unsigned FCmpOpc);
310#define VISITCOMP(CODE, UI, SI, FP) \
311    Value *VisitBin##CODE(const BinaryOperator *E) { \
312      return EmitCompare(E, llvm::ICmpInst::UI, llvm::ICmpInst::SI, \
313                         llvm::FCmpInst::FP); }
314  VISITCOMP(LT, ICMP_ULT, ICMP_SLT, FCMP_OLT);
315  VISITCOMP(GT, ICMP_UGT, ICMP_SGT, FCMP_OGT);
316  VISITCOMP(LE, ICMP_ULE, ICMP_SLE, FCMP_OLE);
317  VISITCOMP(GE, ICMP_UGE, ICMP_SGE, FCMP_OGE);
318  VISITCOMP(EQ, ICMP_EQ , ICMP_EQ , FCMP_OEQ);
319  VISITCOMP(NE, ICMP_NE , ICMP_NE , FCMP_UNE);
320#undef VISITCOMP
321
322  Value *VisitBinAssign     (const BinaryOperator *E);
323
324  Value *VisitBinLAnd       (const BinaryOperator *E);
325  Value *VisitBinLOr        (const BinaryOperator *E);
326  Value *VisitBinComma      (const BinaryOperator *E);
327
328  // Other Operators.
329  Value *VisitBlockExpr(const BlockExpr *BE);
330  Value *VisitConditionalOperator(const ConditionalOperator *CO);
331  Value *VisitChooseExpr(ChooseExpr *CE);
332  Value *VisitVAArgExpr(VAArgExpr *VE);
333  Value *VisitObjCStringLiteral(const ObjCStringLiteral *E) {
334    return CGF.EmitObjCStringLiteral(E);
335  }
336};
337}  // end anonymous namespace.
338
339//===----------------------------------------------------------------------===//
340//                                Utilities
341//===----------------------------------------------------------------------===//
342
343/// EmitConversionToBool - Convert the specified expression value to a
344/// boolean (i1) truth value.  This is equivalent to "Val != 0".
345Value *ScalarExprEmitter::EmitConversionToBool(Value *Src, QualType SrcType) {
346  assert(SrcType->isCanonical() && "EmitScalarConversion strips typedefs");
347
348  if (SrcType->isRealFloatingType()) {
349    // Compare against 0.0 for fp scalars.
350    llvm::Value *Zero = llvm::Constant::getNullValue(Src->getType());
351    return Builder.CreateFCmpUNE(Src, Zero, "tobool");
352  }
353
354  assert((SrcType->isIntegerType() || isa<llvm::PointerType>(Src->getType())) &&
355         "Unknown scalar type to convert");
356
357  // Because of the type rules of C, we often end up computing a logical value,
358  // then zero extending it to int, then wanting it as a logical value again.
359  // Optimize this common case.
360  if (llvm::ZExtInst *ZI = dyn_cast<llvm::ZExtInst>(Src)) {
361    if (ZI->getOperand(0)->getType() == llvm::Type::Int1Ty) {
362      Value *Result = ZI->getOperand(0);
363      // If there aren't any more uses, zap the instruction to save space.
364      // Note that there can be more uses, for example if this
365      // is the result of an assignment.
366      if (ZI->use_empty())
367        ZI->eraseFromParent();
368      return Result;
369    }
370  }
371
372  // Compare against an integer or pointer null.
373  llvm::Value *Zero = llvm::Constant::getNullValue(Src->getType());
374  return Builder.CreateICmpNE(Src, Zero, "tobool");
375}
376
377/// EmitScalarConversion - Emit a conversion from the specified type to the
378/// specified destination type, both of which are LLVM scalar types.
379Value *ScalarExprEmitter::EmitScalarConversion(Value *Src, QualType SrcType,
380                                               QualType DstType) {
381  SrcType = CGF.getContext().getCanonicalType(SrcType);
382  DstType = CGF.getContext().getCanonicalType(DstType);
383  if (SrcType == DstType) return Src;
384
385  if (DstType->isVoidType()) return 0;
386
387  // Handle conversions to bool first, they are special: comparisons against 0.
388  if (DstType->isBooleanType())
389    return EmitConversionToBool(Src, SrcType);
390
391  const llvm::Type *DstTy = ConvertType(DstType);
392
393  // Ignore conversions like int -> uint.
394  if (Src->getType() == DstTy)
395    return Src;
396
397  // Handle pointer conversions next: pointers can only be converted
398  // to/from other pointers and integers. Check for pointer types in
399  // terms of LLVM, as some native types (like Obj-C id) may map to a
400  // pointer type.
401  if (isa<llvm::PointerType>(DstTy)) {
402    // The source value may be an integer, or a pointer.
403    if (isa<llvm::PointerType>(Src->getType()))
404      return Builder.CreateBitCast(Src, DstTy, "conv");
405    assert(SrcType->isIntegerType() && "Not ptr->ptr or int->ptr conversion?");
406    return Builder.CreateIntToPtr(Src, DstTy, "conv");
407  }
408
409  if (isa<llvm::PointerType>(Src->getType())) {
410    // Must be an ptr to int cast.
411    assert(isa<llvm::IntegerType>(DstTy) && "not ptr->int?");
412    return Builder.CreatePtrToInt(Src, DstTy, "conv");
413  }
414
415  // A scalar can be splatted to an extended vector of the same element type
416  if (DstType->isExtVectorType() && !isa<VectorType>(SrcType)) {
417    // Cast the scalar to element type
418    QualType EltTy = DstType->getAsExtVectorType()->getElementType();
419    llvm::Value *Elt = EmitScalarConversion(Src, SrcType, EltTy);
420
421    // Insert the element in element zero of an undef vector
422    llvm::Value *UnV = llvm::UndefValue::get(DstTy);
423    llvm::Value *Idx = llvm::ConstantInt::get(llvm::Type::Int32Ty, 0);
424    UnV = Builder.CreateInsertElement(UnV, Elt, Idx, "tmp");
425
426    // Splat the element across to all elements
427    llvm::SmallVector<llvm::Constant*, 16> Args;
428    unsigned NumElements = cast<llvm::VectorType>(DstTy)->getNumElements();
429    for (unsigned i = 0; i < NumElements; i++)
430      Args.push_back(llvm::ConstantInt::get(llvm::Type::Int32Ty, 0));
431
432    llvm::Constant *Mask = llvm::ConstantVector::get(&Args[0], NumElements);
433    llvm::Value *Yay = Builder.CreateShuffleVector(UnV, UnV, Mask, "splat");
434    return Yay;
435  }
436
437  // Allow bitcast from vector to integer/fp of the same size.
438  if (isa<llvm::VectorType>(Src->getType()) ||
439      isa<llvm::VectorType>(DstTy))
440    return Builder.CreateBitCast(Src, DstTy, "conv");
441
442  // Finally, we have the arithmetic types: real int/float.
443  if (isa<llvm::IntegerType>(Src->getType())) {
444    bool InputSigned = SrcType->isSignedIntegerType();
445    if (isa<llvm::IntegerType>(DstTy))
446      return Builder.CreateIntCast(Src, DstTy, InputSigned, "conv");
447    else if (InputSigned)
448      return Builder.CreateSIToFP(Src, DstTy, "conv");
449    else
450      return Builder.CreateUIToFP(Src, DstTy, "conv");
451  }
452
453  assert(Src->getType()->isFloatingPoint() && "Unknown real conversion");
454  if (isa<llvm::IntegerType>(DstTy)) {
455    if (DstType->isSignedIntegerType())
456      return Builder.CreateFPToSI(Src, DstTy, "conv");
457    else
458      return Builder.CreateFPToUI(Src, DstTy, "conv");
459  }
460
461  assert(DstTy->isFloatingPoint() && "Unknown real conversion");
462  if (DstTy->getTypeID() < Src->getType()->getTypeID())
463    return Builder.CreateFPTrunc(Src, DstTy, "conv");
464  else
465    return Builder.CreateFPExt(Src, DstTy, "conv");
466}
467
468/// EmitComplexToScalarConversion - Emit a conversion from the specified
469/// complex type to the specified destination type, where the destination
470/// type is an LLVM scalar type.
471Value *ScalarExprEmitter::
472EmitComplexToScalarConversion(CodeGenFunction::ComplexPairTy Src,
473                              QualType SrcTy, QualType DstTy) {
474  // Get the source element type.
475  SrcTy = SrcTy->getAsComplexType()->getElementType();
476
477  // Handle conversions to bool first, they are special: comparisons against 0.
478  if (DstTy->isBooleanType()) {
479    //  Complex != 0  -> (Real != 0) | (Imag != 0)
480    Src.first  = EmitScalarConversion(Src.first, SrcTy, DstTy);
481    Src.second = EmitScalarConversion(Src.second, SrcTy, DstTy);
482    return Builder.CreateOr(Src.first, Src.second, "tobool");
483  }
484
485  // C99 6.3.1.7p2: "When a value of complex type is converted to a real type,
486  // the imaginary part of the complex value is discarded and the value of the
487  // real part is converted according to the conversion rules for the
488  // corresponding real type.
489  return EmitScalarConversion(Src.first, SrcTy, DstTy);
490}
491
492
493//===----------------------------------------------------------------------===//
494//                            Visitor Methods
495//===----------------------------------------------------------------------===//
496
497Value *ScalarExprEmitter::VisitExpr(Expr *E) {
498  CGF.ErrorUnsupported(E, "scalar expression");
499  if (E->getType()->isVoidType())
500    return 0;
501  return llvm::UndefValue::get(CGF.ConvertType(E->getType()));
502}
503
504Value *ScalarExprEmitter::VisitShuffleVectorExpr(ShuffleVectorExpr *E) {
505  llvm::SmallVector<llvm::Constant*, 32> indices;
506  for (unsigned i = 2; i < E->getNumSubExprs(); i++) {
507    indices.push_back(cast<llvm::Constant>(CGF.EmitScalarExpr(E->getExpr(i))));
508  }
509  Value* V1 = CGF.EmitScalarExpr(E->getExpr(0));
510  Value* V2 = CGF.EmitScalarExpr(E->getExpr(1));
511  Value* SV = llvm::ConstantVector::get(indices.begin(), indices.size());
512  return Builder.CreateShuffleVector(V1, V2, SV, "shuffle");
513}
514
515Value *ScalarExprEmitter::VisitArraySubscriptExpr(ArraySubscriptExpr *E) {
516  // Emit subscript expressions in rvalue context's.  For most cases, this just
517  // loads the lvalue formed by the subscript expr.  However, we have to be
518  // careful, because the base of a vector subscript is occasionally an rvalue,
519  // so we can't get it as an lvalue.
520  if (!E->getBase()->getType()->isVectorType())
521    return EmitLoadOfLValue(E);
522
523  // Handle the vector case.  The base must be a vector, the index must be an
524  // integer value.
525  Value *Base = Visit(E->getBase());
526  Value *Idx  = Visit(E->getIdx());
527
528  // FIXME: Convert Idx to i32 type.
529  return Builder.CreateExtractElement(Base, Idx, "vecext");
530}
531
532/// VisitImplicitCastExpr - Implicit casts are the same as normal casts, but
533/// also handle things like function to pointer-to-function decay, and array to
534/// pointer decay.
535Value *ScalarExprEmitter::VisitImplicitCastExpr(const ImplicitCastExpr *E) {
536  const Expr *Op = E->getSubExpr();
537
538  // If this is due to array->pointer conversion, emit the array expression as
539  // an l-value.
540  if (Op->getType()->isArrayType()) {
541    // FIXME: For now we assume that all source arrays map to LLVM arrays.  This
542    // will not true when we add support for VLAs.
543    Value *V = EmitLValue(Op).getAddress();  // Bitfields can't be arrays.
544
545    if (!Op->getType()->isVariableArrayType()) {
546      assert(isa<llvm::PointerType>(V->getType()) && "Expected pointer");
547      assert(isa<llvm::ArrayType>(cast<llvm::PointerType>(V->getType())
548                                 ->getElementType()) &&
549             "Expected pointer to array");
550      V = Builder.CreateStructGEP(V, 0, "arraydecay");
551    }
552
553    // The resultant pointer type can be implicitly casted to other pointer
554    // types as well (e.g. void*) and can be implicitly converted to integer.
555    const llvm::Type *DestTy = ConvertType(E->getType());
556    if (V->getType() != DestTy) {
557      if (isa<llvm::PointerType>(DestTy))
558        V = Builder.CreateBitCast(V, DestTy, "ptrconv");
559      else {
560        assert(isa<llvm::IntegerType>(DestTy) && "Unknown array decay");
561        V = Builder.CreatePtrToInt(V, DestTy, "ptrconv");
562      }
563    }
564    return V;
565
566  } else if (E->getType()->isReferenceType()) {
567    return EmitLValue(Op).getAddress();
568  }
569
570  return EmitCastExpr(Op, E->getType());
571}
572
573
574// VisitCastExpr - Emit code for an explicit or implicit cast.  Implicit casts
575// have to handle a more broad range of conversions than explicit casts, as they
576// handle things like function to ptr-to-function decay etc.
577Value *ScalarExprEmitter::EmitCastExpr(const Expr *E, QualType DestTy) {
578  // Handle cases where the source is an non-complex type.
579
580  if (!CGF.hasAggregateLLVMType(E->getType())) {
581    Value *Src = Visit(const_cast<Expr*>(E));
582
583    // Use EmitScalarConversion to perform the conversion.
584    return EmitScalarConversion(Src, E->getType(), DestTy);
585  }
586
587  if (E->getType()->isAnyComplexType()) {
588    // Handle cases where the source is a complex type.
589    return EmitComplexToScalarConversion(CGF.EmitComplexExpr(E), E->getType(),
590                                         DestTy);
591  }
592
593  // Okay, this is a cast from an aggregate.  It must be a cast to void.  Just
594  // evaluate the result and return.
595  CGF.EmitAggExpr(E, 0, false);
596  return 0;
597}
598
599Value *ScalarExprEmitter::VisitStmtExpr(const StmtExpr *E) {
600  return CGF.EmitCompoundStmt(*E->getSubStmt(),
601                              !E->getType()->isVoidType()).getScalarVal();
602}
603
604Value *ScalarExprEmitter::VisitBlockDeclRefExpr(const BlockDeclRefExpr *E) {
605  return Builder.CreateLoad(CGF.GetAddrOfBlockDecl(E), false, "tmp");
606}
607
608//===----------------------------------------------------------------------===//
609//                             Unary Operators
610//===----------------------------------------------------------------------===//
611
612Value *ScalarExprEmitter::VisitPrePostIncDec(const UnaryOperator *E,
613                                             bool isInc, bool isPre) {
614  LValue LV = EmitLValue(E->getSubExpr());
615  // FIXME: Handle volatile!
616  Value *InVal = CGF.EmitLoadOfLValue(LV, // false
617                                     E->getSubExpr()->getType()).getScalarVal();
618
619  int AmountVal = isInc ? 1 : -1;
620
621  Value *NextVal;
622  if (isa<llvm::PointerType>(InVal->getType())) {
623    // FIXME: This isn't right for VLAs.
624    NextVal = llvm::ConstantInt::get(llvm::Type::Int32Ty, AmountVal);
625    NextVal = Builder.CreateGEP(InVal, NextVal, "ptrincdec");
626  } else if (InVal->getType() == llvm::Type::Int1Ty && isInc) {
627    // Bool++ is an interesting case, due to promotion rules, we get:
628    // Bool++ -> Bool = Bool+1 -> Bool = (int)Bool+1 ->
629    // Bool = ((int)Bool+1) != 0
630    // An interesting aspect of this is that increment is always true.
631    // Decrement does not have this property.
632    NextVal = llvm::ConstantInt::getTrue();
633  } else {
634    // Add the inc/dec to the real part.
635    if (isa<llvm::IntegerType>(InVal->getType()))
636      NextVal = llvm::ConstantInt::get(InVal->getType(), AmountVal);
637    else if (InVal->getType() == llvm::Type::FloatTy)
638      NextVal =
639        llvm::ConstantFP::get(llvm::APFloat(static_cast<float>(AmountVal)));
640    else if (InVal->getType() == llvm::Type::DoubleTy)
641      NextVal =
642        llvm::ConstantFP::get(llvm::APFloat(static_cast<double>(AmountVal)));
643    else {
644      llvm::APFloat F(static_cast<float>(AmountVal));
645      bool ignored;
646      F.convert(CGF.Target.getLongDoubleFormat(), llvm::APFloat::rmTowardZero,
647                &ignored);
648      NextVal = llvm::ConstantFP::get(F);
649    }
650    NextVal = Builder.CreateAdd(InVal, NextVal, isInc ? "inc" : "dec");
651  }
652
653  // Store the updated result through the lvalue.
654  CGF.EmitStoreThroughLValue(RValue::get(NextVal), LV,
655                             E->getSubExpr()->getType());
656
657  // If this is a postinc, return the value read from memory, otherwise use the
658  // updated value.
659  return isPre ? NextVal : InVal;
660}
661
662
663Value *ScalarExprEmitter::VisitUnaryMinus(const UnaryOperator *E) {
664  Value *Op = Visit(E->getSubExpr());
665  return Builder.CreateNeg(Op, "neg");
666}
667
668Value *ScalarExprEmitter::VisitUnaryNot(const UnaryOperator *E) {
669  Value *Op = Visit(E->getSubExpr());
670  return Builder.CreateNot(Op, "neg");
671}
672
673Value *ScalarExprEmitter::VisitUnaryLNot(const UnaryOperator *E) {
674  // Compare operand to zero.
675  Value *BoolVal = CGF.EvaluateExprAsBool(E->getSubExpr());
676
677  // Invert value.
678  // TODO: Could dynamically modify easy computations here.  For example, if
679  // the operand is an icmp ne, turn into icmp eq.
680  BoolVal = Builder.CreateNot(BoolVal, "lnot");
681
682  // ZExt result to int.
683  return Builder.CreateZExt(BoolVal, CGF.LLVMIntTy, "lnot.ext");
684}
685
686/// VisitSizeOfAlignOfExpr - Return the size or alignment of the type of
687/// argument of the sizeof expression as an integer.
688Value *
689ScalarExprEmitter::VisitSizeOfAlignOfExpr(const SizeOfAlignOfExpr *E) {
690  QualType TypeToSize = E->getTypeOfArgument();
691  if (E->isSizeOf()) {
692    if (const VariableArrayType *VAT =
693          CGF.getContext().getAsVariableArrayType(TypeToSize)) {
694      if (E->isArgumentType()) {
695        // sizeof(type) - make sure to emit the VLA size.
696        CGF.EmitVLASize(TypeToSize);
697      }
698
699      return CGF.GetVLASize(VAT);
700    }
701  }
702
703  // If this isn't sizeof(vla), the result must be constant; use the
704  // constant folding logic so we don't have to duplicate it here.
705  Expr::EvalResult Result;
706  E->Evaluate(Result, CGF.getContext());
707  return llvm::ConstantInt::get(Result.Val.getInt());
708}
709
710Value *ScalarExprEmitter::VisitUnaryReal(const UnaryOperator *E) {
711  Expr *Op = E->getSubExpr();
712  if (Op->getType()->isAnyComplexType())
713    return CGF.EmitComplexExpr(Op).first;
714  return Visit(Op);
715}
716Value *ScalarExprEmitter::VisitUnaryImag(const UnaryOperator *E) {
717  Expr *Op = E->getSubExpr();
718  if (Op->getType()->isAnyComplexType())
719    return CGF.EmitComplexExpr(Op).second;
720
721  // __imag on a scalar returns zero.  Emit it the subexpr to ensure side
722  // effects are evaluated.
723  CGF.EmitScalarExpr(Op);
724  return llvm::Constant::getNullValue(ConvertType(E->getType()));
725}
726
727Value *ScalarExprEmitter::VisitUnaryOffsetOf(const UnaryOperator *E)
728{
729  Value* ResultAsPtr = EmitLValue(E->getSubExpr()).getAddress();
730  const llvm::Type* ResultType = ConvertType(E->getType());
731  return Builder.CreatePtrToInt(ResultAsPtr, ResultType, "offsetof");
732}
733
734//===----------------------------------------------------------------------===//
735//                           Binary Operators
736//===----------------------------------------------------------------------===//
737
738BinOpInfo ScalarExprEmitter::EmitBinOps(const BinaryOperator *E) {
739  BinOpInfo Result;
740  Result.LHS = Visit(E->getLHS());
741  Result.RHS = Visit(E->getRHS());
742  Result.Ty  = E->getType();
743  Result.E = E;
744  return Result;
745}
746
747Value *ScalarExprEmitter::EmitCompoundAssign(const CompoundAssignOperator *E,
748                      Value *(ScalarExprEmitter::*Func)(const BinOpInfo &)) {
749  QualType LHSTy = E->getLHS()->getType(), RHSTy = E->getRHS()->getType();
750
751  BinOpInfo OpInfo;
752
753  // Load the LHS and RHS operands.
754  LValue LHSLV = EmitLValue(E->getLHS());
755  OpInfo.LHS = EmitLoadOfLValue(LHSLV, LHSTy);
756
757  // Determine the computation type.  If the RHS is complex, then this is one of
758  // the add/sub/mul/div operators.  All of these operators can be computed in
759  // with just their real component even though the computation domain really is
760  // complex.
761  QualType ComputeType = E->getComputationType();
762
763  // If the computation type is complex, then the RHS is complex.  Emit the RHS.
764  if (const ComplexType *CT = ComputeType->getAsComplexType()) {
765    ComputeType = CT->getElementType();
766
767    // Emit the RHS, only keeping the real component.
768    OpInfo.RHS = CGF.EmitComplexExpr(E->getRHS()).first;
769    RHSTy = RHSTy->getAsComplexType()->getElementType();
770  } else {
771    // Otherwise the RHS is a simple scalar value.
772    OpInfo.RHS = Visit(E->getRHS());
773  }
774
775  QualType LComputeTy, RComputeTy, ResultTy;
776
777  // Compound assignment does not contain enough information about all
778  // the types involved for pointer arithmetic cases. Figure it out
779  // here for now.
780  if (E->getLHS()->getType()->isPointerType()) {
781    // Pointer arithmetic cases: ptr +=,-= int and ptr -= ptr,
782    assert((E->getOpcode() == BinaryOperator::AddAssign ||
783            E->getOpcode() == BinaryOperator::SubAssign) &&
784           "Invalid compound assignment operator on pointer type.");
785    LComputeTy = E->getLHS()->getType();
786
787    if (E->getRHS()->getType()->isPointerType()) {
788      // Degenerate case of (ptr -= ptr) allowed by GCC implicit cast
789      // extension, the conversion from the pointer difference back to
790      // the LHS type is handled at the end.
791      assert(E->getOpcode() == BinaryOperator::SubAssign &&
792             "Invalid compound assignment operator on pointer type.");
793      RComputeTy = E->getLHS()->getType();
794      ResultTy = CGF.getContext().getPointerDiffType();
795    } else {
796      RComputeTy = E->getRHS()->getType();
797      ResultTy = LComputeTy;
798    }
799  } else if (E->getRHS()->getType()->isPointerType()) {
800    // Degenerate case of (int += ptr) allowed by GCC implicit cast
801    // extension.
802    assert(E->getOpcode() == BinaryOperator::AddAssign &&
803           "Invalid compound assignment operator on pointer type.");
804    LComputeTy = E->getLHS()->getType();
805    RComputeTy = E->getRHS()->getType();
806    ResultTy = RComputeTy;
807  } else {
808    LComputeTy = RComputeTy = ResultTy = ComputeType;
809  }
810
811  // Convert the LHS/RHS values to the computation type.
812  OpInfo.LHS = EmitScalarConversion(OpInfo.LHS, LHSTy, LComputeTy);
813  OpInfo.RHS = EmitScalarConversion(OpInfo.RHS, RHSTy, RComputeTy);
814  OpInfo.Ty = ResultTy;
815  OpInfo.E = E;
816
817  // Expand the binary operator.
818  Value *Result = (this->*Func)(OpInfo);
819
820  // Convert the result back to the LHS type.
821  Result = EmitScalarConversion(Result, ResultTy, LHSTy);
822
823  // Store the result value into the LHS lvalue. Bit-fields are
824  // handled specially because the result is altered by the store,
825  // i.e., [C99 6.5.16p1] 'An assignment expression has the value of
826  // the left operand after the assignment...'.
827  if (LHSLV.isBitfield())
828    CGF.EmitStoreThroughBitfieldLValue(RValue::get(Result), LHSLV, LHSTy,
829                                       &Result);
830  else
831    CGF.EmitStoreThroughLValue(RValue::get(Result), LHSLV, LHSTy);
832
833  return Result;
834}
835
836
837Value *ScalarExprEmitter::EmitDiv(const BinOpInfo &Ops) {
838  if (Ops.LHS->getType()->isFPOrFPVector())
839    return Builder.CreateFDiv(Ops.LHS, Ops.RHS, "div");
840  else if (Ops.Ty->isUnsignedIntegerType())
841    return Builder.CreateUDiv(Ops.LHS, Ops.RHS, "div");
842  else
843    return Builder.CreateSDiv(Ops.LHS, Ops.RHS, "div");
844}
845
846Value *ScalarExprEmitter::EmitRem(const BinOpInfo &Ops) {
847  // Rem in C can't be a floating point type: C99 6.5.5p2.
848  if (Ops.Ty->isUnsignedIntegerType())
849    return Builder.CreateURem(Ops.LHS, Ops.RHS, "rem");
850  else
851    return Builder.CreateSRem(Ops.LHS, Ops.RHS, "rem");
852}
853
854
855Value *ScalarExprEmitter::EmitAdd(const BinOpInfo &Ops) {
856  if (!Ops.Ty->isPointerType())
857    return Builder.CreateAdd(Ops.LHS, Ops.RHS, "add");
858
859  // FIXME: What about a pointer to a VLA?
860  Value *Ptr, *Idx;
861  Expr *IdxExp;
862  const PointerType *PT;
863  if ((PT = Ops.E->getLHS()->getType()->getAsPointerType())) {
864    Ptr = Ops.LHS;
865    Idx = Ops.RHS;
866    IdxExp = Ops.E->getRHS();
867  } else {                                           // int + pointer
868    PT = Ops.E->getRHS()->getType()->getAsPointerType();
869    assert(PT && "Invalid add expr");
870    Ptr = Ops.RHS;
871    Idx = Ops.LHS;
872    IdxExp = Ops.E->getLHS();
873  }
874
875  unsigned Width = cast<llvm::IntegerType>(Idx->getType())->getBitWidth();
876  if (Width < CGF.LLVMPointerWidth) {
877    // Zero or sign extend the pointer value based on whether the index is
878    // signed or not.
879    const llvm::Type *IdxType = llvm::IntegerType::get(CGF.LLVMPointerWidth);
880    if (IdxExp->getType()->isSignedIntegerType())
881      Idx = Builder.CreateSExt(Idx, IdxType, "idx.ext");
882    else
883      Idx = Builder.CreateZExt(Idx, IdxType, "idx.ext");
884  }
885
886  // Explicitly handle GNU void* and function pointer arithmetic
887  // extensions. The GNU void* casts amount to no-ops since our void*
888  // type is i8*, but this is future proof.
889  const QualType ElementType = PT->getPointeeType();
890  if (ElementType->isVoidType() || ElementType->isFunctionType()) {
891    const llvm::Type *i8Ty = llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
892    Value *Casted = Builder.CreateBitCast(Ptr, i8Ty);
893    Value *Res = Builder.CreateGEP(Casted, Idx, "sub.ptr");
894    return Builder.CreateBitCast(Res, Ptr->getType());
895  }
896
897  return Builder.CreateGEP(Ptr, Idx, "add.ptr");
898}
899
900Value *ScalarExprEmitter::EmitSub(const BinOpInfo &Ops) {
901  if (!isa<llvm::PointerType>(Ops.LHS->getType()))
902    return Builder.CreateSub(Ops.LHS, Ops.RHS, "sub");
903
904  const QualType LHSType = Ops.E->getLHS()->getType();
905  const QualType LHSElementType = LHSType->getAsPointerType()->getPointeeType();
906  if (!isa<llvm::PointerType>(Ops.RHS->getType())) {
907    // pointer - int
908    Value *Idx = Ops.RHS;
909    unsigned Width = cast<llvm::IntegerType>(Idx->getType())->getBitWidth();
910    if (Width < CGF.LLVMPointerWidth) {
911      // Zero or sign extend the pointer value based on whether the index is
912      // signed or not.
913      const llvm::Type *IdxType = llvm::IntegerType::get(CGF.LLVMPointerWidth);
914      if (Ops.E->getRHS()->getType()->isSignedIntegerType())
915        Idx = Builder.CreateSExt(Idx, IdxType, "idx.ext");
916      else
917        Idx = Builder.CreateZExt(Idx, IdxType, "idx.ext");
918    }
919    Idx = Builder.CreateNeg(Idx, "sub.ptr.neg");
920
921    // FIXME: The pointer could point to a VLA.
922
923    // Explicitly handle GNU void* and function pointer arithmetic
924    // extensions. The GNU void* casts amount to no-ops since our
925    // void* type is i8*, but this is future proof.
926    if (LHSElementType->isVoidType() || LHSElementType->isFunctionType()) {
927      const llvm::Type *i8Ty = llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
928      Value *LHSCasted = Builder.CreateBitCast(Ops.LHS, i8Ty);
929      Value *Res = Builder.CreateGEP(LHSCasted, Idx, "sub.ptr");
930      return Builder.CreateBitCast(Res, Ops.LHS->getType());
931    }
932
933    return Builder.CreateGEP(Ops.LHS, Idx, "sub.ptr");
934  } else {
935    // pointer - pointer
936    Value *LHS = Ops.LHS;
937    Value *RHS = Ops.RHS;
938
939    uint64_t ElementSize;
940
941    // Handle GCC extension for pointer arithmetic on void* and function pointer
942    // types.
943    if (LHSElementType->isVoidType() || LHSElementType->isFunctionType()) {
944      ElementSize = 1;
945    } else {
946      ElementSize = CGF.getContext().getTypeSize(LHSElementType) / 8;
947    }
948
949    const llvm::Type *ResultType = ConvertType(Ops.Ty);
950    LHS = Builder.CreatePtrToInt(LHS, ResultType, "sub.ptr.lhs.cast");
951    RHS = Builder.CreatePtrToInt(RHS, ResultType, "sub.ptr.rhs.cast");
952    Value *BytesBetween = Builder.CreateSub(LHS, RHS, "sub.ptr.sub");
953
954    // Optimize out the shift for element size of 1.
955    if (ElementSize == 1)
956      return BytesBetween;
957
958    // HACK: LLVM doesn't have an divide instruction that 'knows' there is no
959    // remainder.  As such, we handle common power-of-two cases here to generate
960    // better code. See PR2247.
961    if (llvm::isPowerOf2_64(ElementSize)) {
962      Value *ShAmt =
963        llvm::ConstantInt::get(ResultType, llvm::Log2_64(ElementSize));
964      return Builder.CreateAShr(BytesBetween, ShAmt, "sub.ptr.shr");
965    }
966
967    // Otherwise, do a full sdiv.
968    Value *BytesPerElt = llvm::ConstantInt::get(ResultType, ElementSize);
969    return Builder.CreateSDiv(BytesBetween, BytesPerElt, "sub.ptr.div");
970  }
971}
972
973Value *ScalarExprEmitter::EmitShl(const BinOpInfo &Ops) {
974  // LLVM requires the LHS and RHS to be the same type: promote or truncate the
975  // RHS to the same size as the LHS.
976  Value *RHS = Ops.RHS;
977  if (Ops.LHS->getType() != RHS->getType())
978    RHS = Builder.CreateIntCast(RHS, Ops.LHS->getType(), false, "sh_prom");
979
980  return Builder.CreateShl(Ops.LHS, RHS, "shl");
981}
982
983Value *ScalarExprEmitter::EmitShr(const BinOpInfo &Ops) {
984  // LLVM requires the LHS and RHS to be the same type: promote or truncate the
985  // RHS to the same size as the LHS.
986  Value *RHS = Ops.RHS;
987  if (Ops.LHS->getType() != RHS->getType())
988    RHS = Builder.CreateIntCast(RHS, Ops.LHS->getType(), false, "sh_prom");
989
990  if (Ops.Ty->isUnsignedIntegerType())
991    return Builder.CreateLShr(Ops.LHS, RHS, "shr");
992  return Builder.CreateAShr(Ops.LHS, RHS, "shr");
993}
994
995Value *ScalarExprEmitter::EmitCompare(const BinaryOperator *E,unsigned UICmpOpc,
996                                      unsigned SICmpOpc, unsigned FCmpOpc) {
997  Value *Result;
998  QualType LHSTy = E->getLHS()->getType();
999  if (!LHSTy->isAnyComplexType() && !LHSTy->isVectorType()) {
1000    Value *LHS = Visit(E->getLHS());
1001    Value *RHS = Visit(E->getRHS());
1002
1003    if (LHS->getType()->isFloatingPoint()) {
1004      Result = Builder.CreateFCmp((llvm::CmpInst::Predicate)FCmpOpc,
1005                                  LHS, RHS, "cmp");
1006    } else if (LHSTy->isSignedIntegerType()) {
1007      Result = Builder.CreateICmp((llvm::ICmpInst::Predicate)SICmpOpc,
1008                                  LHS, RHS, "cmp");
1009    } else {
1010      // Unsigned integers and pointers.
1011      Result = Builder.CreateICmp((llvm::ICmpInst::Predicate)UICmpOpc,
1012                                  LHS, RHS, "cmp");
1013    }
1014  } else if (LHSTy->isVectorType()) {
1015    Value *LHS = Visit(E->getLHS());
1016    Value *RHS = Visit(E->getRHS());
1017
1018    if (LHS->getType()->isFPOrFPVector()) {
1019      Result = Builder.CreateVFCmp((llvm::CmpInst::Predicate)FCmpOpc,
1020                                  LHS, RHS, "cmp");
1021    } else if (LHSTy->isUnsignedIntegerType()) {
1022      Result = Builder.CreateVICmp((llvm::CmpInst::Predicate)UICmpOpc,
1023                                  LHS, RHS, "cmp");
1024    } else {
1025      // Signed integers and pointers.
1026      Result = Builder.CreateVICmp((llvm::CmpInst::Predicate)SICmpOpc,
1027                                  LHS, RHS, "cmp");
1028    }
1029    return Result;
1030  } else {
1031    // Complex Comparison: can only be an equality comparison.
1032    CodeGenFunction::ComplexPairTy LHS = CGF.EmitComplexExpr(E->getLHS());
1033    CodeGenFunction::ComplexPairTy RHS = CGF.EmitComplexExpr(E->getRHS());
1034
1035    QualType CETy = LHSTy->getAsComplexType()->getElementType();
1036
1037    Value *ResultR, *ResultI;
1038    if (CETy->isRealFloatingType()) {
1039      ResultR = Builder.CreateFCmp((llvm::FCmpInst::Predicate)FCmpOpc,
1040                                   LHS.first, RHS.first, "cmp.r");
1041      ResultI = Builder.CreateFCmp((llvm::FCmpInst::Predicate)FCmpOpc,
1042                                   LHS.second, RHS.second, "cmp.i");
1043    } else {
1044      // Complex comparisons can only be equality comparisons.  As such, signed
1045      // and unsigned opcodes are the same.
1046      ResultR = Builder.CreateICmp((llvm::ICmpInst::Predicate)UICmpOpc,
1047                                   LHS.first, RHS.first, "cmp.r");
1048      ResultI = Builder.CreateICmp((llvm::ICmpInst::Predicate)UICmpOpc,
1049                                   LHS.second, RHS.second, "cmp.i");
1050    }
1051
1052    if (E->getOpcode() == BinaryOperator::EQ) {
1053      Result = Builder.CreateAnd(ResultR, ResultI, "and.ri");
1054    } else {
1055      assert(E->getOpcode() == BinaryOperator::NE &&
1056             "Complex comparison other than == or != ?");
1057      Result = Builder.CreateOr(ResultR, ResultI, "or.ri");
1058    }
1059  }
1060
1061  return EmitScalarConversion(Result, CGF.getContext().BoolTy, E->getType());
1062}
1063
1064Value *ScalarExprEmitter::VisitBinAssign(const BinaryOperator *E) {
1065  LValue LHS = EmitLValue(E->getLHS());
1066  Value *RHS = Visit(E->getRHS());
1067
1068  // Store the value into the LHS.  Bit-fields are handled specially
1069  // because the result is altered by the store, i.e., [C99 6.5.16p1]
1070  // 'An assignment expression has the value of the left operand after
1071  // the assignment...'.
1072  // FIXME: Volatility!
1073  if (LHS.isBitfield())
1074    CGF.EmitStoreThroughBitfieldLValue(RValue::get(RHS), LHS, E->getType(),
1075                                       &RHS);
1076  else
1077    CGF.EmitStoreThroughLValue(RValue::get(RHS), LHS, E->getType());
1078
1079  // Return the RHS.
1080  return RHS;
1081}
1082
1083Value *ScalarExprEmitter::VisitBinLAnd(const BinaryOperator *E) {
1084  // If we have 0 && RHS, see if we can elide RHS, if so, just return 0.
1085  // If we have 1 && X, just emit X without inserting the control flow.
1086  if (int Cond = CGF.ConstantFoldsToSimpleInteger(E->getLHS())) {
1087    if (Cond == 1) { // If we have 1 && X, just emit X.
1088      Value *RHSCond = CGF.EvaluateExprAsBool(E->getRHS());
1089      // ZExt result to int.
1090      return Builder.CreateZExt(RHSCond, CGF.LLVMIntTy, "land.ext");
1091    }
1092
1093    // 0 && RHS: If it is safe, just elide the RHS, and return 0.
1094    if (!CGF.ContainsLabel(E->getRHS()))
1095      return llvm::Constant::getNullValue(CGF.LLVMIntTy);
1096  }
1097
1098  llvm::BasicBlock *ContBlock = CGF.createBasicBlock("land.end");
1099  llvm::BasicBlock *RHSBlock  = CGF.createBasicBlock("land.rhs");
1100
1101  // Branch on the LHS first.  If it is false, go to the failure (cont) block.
1102  CGF.EmitBranchOnBoolExpr(E->getLHS(), RHSBlock, ContBlock);
1103
1104  // Any edges into the ContBlock are now from an (indeterminate number of)
1105  // edges from this first condition.  All of these values will be false.  Start
1106  // setting up the PHI node in the Cont Block for this.
1107  llvm::PHINode *PN = llvm::PHINode::Create(llvm::Type::Int1Ty, "", ContBlock);
1108  PN->reserveOperandSpace(2);  // Normal case, two inputs.
1109  for (llvm::pred_iterator PI = pred_begin(ContBlock), PE = pred_end(ContBlock);
1110       PI != PE; ++PI)
1111    PN->addIncoming(llvm::ConstantInt::getFalse(), *PI);
1112
1113  CGF.EmitBlock(RHSBlock);
1114  Value *RHSCond = CGF.EvaluateExprAsBool(E->getRHS());
1115
1116  // Reaquire the RHS block, as there may be subblocks inserted.
1117  RHSBlock = Builder.GetInsertBlock();
1118
1119  // Emit an unconditional branch from this block to ContBlock.  Insert an entry
1120  // into the phi node for the edge with the value of RHSCond.
1121  CGF.EmitBlock(ContBlock);
1122  PN->addIncoming(RHSCond, RHSBlock);
1123
1124  // ZExt result to int.
1125  return Builder.CreateZExt(PN, CGF.LLVMIntTy, "land.ext");
1126}
1127
1128Value *ScalarExprEmitter::VisitBinLOr(const BinaryOperator *E) {
1129  // If we have 1 || RHS, see if we can elide RHS, if so, just return 1.
1130  // If we have 0 || X, just emit X without inserting the control flow.
1131  if (int Cond = CGF.ConstantFoldsToSimpleInteger(E->getLHS())) {
1132    if (Cond == -1) { // If we have 0 || X, just emit X.
1133      Value *RHSCond = CGF.EvaluateExprAsBool(E->getRHS());
1134      // ZExt result to int.
1135      return Builder.CreateZExt(RHSCond, CGF.LLVMIntTy, "lor.ext");
1136    }
1137
1138    // 1 || RHS: If it is safe, just elide the RHS, and return 1.
1139    if (!CGF.ContainsLabel(E->getRHS()))
1140      return llvm::ConstantInt::get(CGF.LLVMIntTy, 1);
1141  }
1142
1143  llvm::BasicBlock *ContBlock = CGF.createBasicBlock("lor.end");
1144  llvm::BasicBlock *RHSBlock = CGF.createBasicBlock("lor.rhs");
1145
1146  // Branch on the LHS first.  If it is true, go to the success (cont) block.
1147  CGF.EmitBranchOnBoolExpr(E->getLHS(), ContBlock, RHSBlock);
1148
1149  // Any edges into the ContBlock are now from an (indeterminate number of)
1150  // edges from this first condition.  All of these values will be true.  Start
1151  // setting up the PHI node in the Cont Block for this.
1152  llvm::PHINode *PN = llvm::PHINode::Create(llvm::Type::Int1Ty, "", ContBlock);
1153  PN->reserveOperandSpace(2);  // Normal case, two inputs.
1154  for (llvm::pred_iterator PI = pred_begin(ContBlock), PE = pred_end(ContBlock);
1155       PI != PE; ++PI)
1156    PN->addIncoming(llvm::ConstantInt::getTrue(), *PI);
1157
1158  // Emit the RHS condition as a bool value.
1159  CGF.EmitBlock(RHSBlock);
1160  Value *RHSCond = CGF.EvaluateExprAsBool(E->getRHS());
1161
1162  // Reaquire the RHS block, as there may be subblocks inserted.
1163  RHSBlock = Builder.GetInsertBlock();
1164
1165  // Emit an unconditional branch from this block to ContBlock.  Insert an entry
1166  // into the phi node for the edge with the value of RHSCond.
1167  CGF.EmitBlock(ContBlock);
1168  PN->addIncoming(RHSCond, RHSBlock);
1169
1170  // ZExt result to int.
1171  return Builder.CreateZExt(PN, CGF.LLVMIntTy, "lor.ext");
1172}
1173
1174Value *ScalarExprEmitter::VisitBinComma(const BinaryOperator *E) {
1175  CGF.EmitStmt(E->getLHS());
1176  CGF.EnsureInsertPoint();
1177  return Visit(E->getRHS());
1178}
1179
1180//===----------------------------------------------------------------------===//
1181//                             Other Operators
1182//===----------------------------------------------------------------------===//
1183
1184/// isCheapEnoughToEvaluateUnconditionally - Return true if the specified
1185/// expression is cheap enough and side-effect-free enough to evaluate
1186/// unconditionally instead of conditionally.  This is used to convert control
1187/// flow into selects in some cases.
1188static bool isCheapEnoughToEvaluateUnconditionally(const Expr *E) {
1189  if (const ParenExpr *PE = dyn_cast<ParenExpr>(E))
1190    return isCheapEnoughToEvaluateUnconditionally(PE->getSubExpr());
1191
1192  // TODO: Allow anything we can constant fold to an integer or fp constant.
1193  if (isa<IntegerLiteral>(E) || isa<CharacterLiteral>(E) ||
1194      isa<FloatingLiteral>(E))
1195    return true;
1196
1197  // Non-volatile automatic variables too, to get "cond ? X : Y" where
1198  // X and Y are local variables.
1199  if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
1200    if (const VarDecl *VD = dyn_cast<VarDecl>(DRE->getDecl()))
1201      if (VD->hasLocalStorage() && !VD->getType().isVolatileQualified())
1202        return true;
1203
1204  return false;
1205}
1206
1207
1208Value *ScalarExprEmitter::
1209VisitConditionalOperator(const ConditionalOperator *E) {
1210  // If the condition constant folds and can be elided, try to avoid emitting
1211  // the condition and the dead arm.
1212  if (int Cond = CGF.ConstantFoldsToSimpleInteger(E->getCond())){
1213    Expr *Live = E->getLHS(), *Dead = E->getRHS();
1214    if (Cond == -1)
1215      std::swap(Live, Dead);
1216
1217    // If the dead side doesn't have labels we need, and if the Live side isn't
1218    // the gnu missing ?: extension (which we could handle, but don't bother
1219    // to), just emit the Live part.
1220    if ((!Dead || !CGF.ContainsLabel(Dead)) &&  // No labels in dead part
1221        Live)                                   // Live part isn't missing.
1222      return Visit(Live);
1223  }
1224
1225
1226  // If this is a really simple expression (like x ? 4 : 5), emit this as a
1227  // select instead of as control flow.  We can only do this if it is cheap and
1228  // safe to evaluate the LHS and RHS unconditionally.
1229  if (E->getLHS() && isCheapEnoughToEvaluateUnconditionally(E->getLHS()) &&
1230      isCheapEnoughToEvaluateUnconditionally(E->getRHS())) {
1231    llvm::Value *CondV = CGF.EvaluateExprAsBool(E->getCond());
1232    llvm::Value *LHS = Visit(E->getLHS());
1233    llvm::Value *RHS = Visit(E->getRHS());
1234    return Builder.CreateSelect(CondV, LHS, RHS, "cond");
1235  }
1236
1237
1238  llvm::BasicBlock *LHSBlock = CGF.createBasicBlock("cond.true");
1239  llvm::BasicBlock *RHSBlock = CGF.createBasicBlock("cond.false");
1240  llvm::BasicBlock *ContBlock = CGF.createBasicBlock("cond.end");
1241  Value *CondVal = 0;
1242
1243  // If we don't have the GNU missing condition extension, emit a branch on
1244  // bool the normal way.
1245  if (E->getLHS()) {
1246    // Otherwise, just use EmitBranchOnBoolExpr to get small and simple code for
1247    // the branch on bool.
1248    CGF.EmitBranchOnBoolExpr(E->getCond(), LHSBlock, RHSBlock);
1249  } else {
1250    // Otherwise, for the ?: extension, evaluate the conditional and then
1251    // convert it to bool the hard way.  We do this explicitly because we need
1252    // the unconverted value for the missing middle value of the ?:.
1253    CondVal = CGF.EmitScalarExpr(E->getCond());
1254
1255    // In some cases, EmitScalarConversion will delete the "CondVal" expression
1256    // if there are no extra uses (an optimization).  Inhibit this by making an
1257    // extra dead use, because we're going to add a use of CondVal later.  We
1258    // don't use the builder for this, because we don't want it to get optimized
1259    // away.  This leaves dead code, but the ?: extension isn't common.
1260    new llvm::BitCastInst(CondVal, CondVal->getType(), "dummy?:holder",
1261                          Builder.GetInsertBlock());
1262
1263    Value *CondBoolVal =
1264      CGF.EmitScalarConversion(CondVal, E->getCond()->getType(),
1265                               CGF.getContext().BoolTy);
1266    Builder.CreateCondBr(CondBoolVal, LHSBlock, RHSBlock);
1267  }
1268
1269  CGF.EmitBlock(LHSBlock);
1270
1271  // Handle the GNU extension for missing LHS.
1272  Value *LHS;
1273  if (E->getLHS())
1274    LHS = Visit(E->getLHS());
1275  else    // Perform promotions, to handle cases like "short ?: int"
1276    LHS = EmitScalarConversion(CondVal, E->getCond()->getType(), E->getType());
1277
1278  LHSBlock = Builder.GetInsertBlock();
1279  CGF.EmitBranch(ContBlock);
1280
1281  CGF.EmitBlock(RHSBlock);
1282
1283  Value *RHS = Visit(E->getRHS());
1284  RHSBlock = Builder.GetInsertBlock();
1285  CGF.EmitBranch(ContBlock);
1286
1287  CGF.EmitBlock(ContBlock);
1288
1289  if (!LHS || !RHS) {
1290    assert(E->getType()->isVoidType() && "Non-void value should have a value");
1291    return 0;
1292  }
1293
1294  // Create a PHI node for the real part.
1295  llvm::PHINode *PN = Builder.CreatePHI(LHS->getType(), "cond");
1296  PN->reserveOperandSpace(2);
1297  PN->addIncoming(LHS, LHSBlock);
1298  PN->addIncoming(RHS, RHSBlock);
1299  return PN;
1300}
1301
1302Value *ScalarExprEmitter::VisitChooseExpr(ChooseExpr *E) {
1303  // Emit the LHS or RHS as appropriate.
1304  return
1305    Visit(E->isConditionTrue(CGF.getContext()) ? E->getLHS() : E->getRHS());
1306}
1307
1308Value *ScalarExprEmitter::VisitVAArgExpr(VAArgExpr *VE) {
1309  llvm::Value *ArgValue = CGF.EmitVAListRef(VE->getSubExpr());
1310  llvm::Value *ArgPtr = CGF.EmitVAArg(ArgValue, VE->getType());
1311
1312  // If EmitVAArg fails, we fall back to the LLVM instruction.
1313  if (!ArgPtr)
1314    return Builder.CreateVAArg(ArgValue, ConvertType(VE->getType()));
1315
1316  // FIXME: volatile?
1317  return Builder.CreateLoad(ArgPtr);
1318}
1319
1320Value *ScalarExprEmitter::VisitBlockExpr(const BlockExpr *BE) {
1321  llvm::Value *V = CGF.BuildBlockLiteralTmp(BE);
1322  return V;
1323}
1324
1325//===----------------------------------------------------------------------===//
1326//                         Entry Point into this File
1327//===----------------------------------------------------------------------===//
1328
1329/// EmitComplexExpr - Emit the computation of the specified expression of
1330/// complex type, ignoring the result.
1331Value *CodeGenFunction::EmitScalarExpr(const Expr *E) {
1332  assert(E && !hasAggregateLLVMType(E->getType()) &&
1333         "Invalid scalar expression to emit");
1334
1335  return ScalarExprEmitter(*this).Visit(const_cast<Expr*>(E));
1336}
1337
1338/// EmitScalarConversion - Emit a conversion from the specified type to the
1339/// specified destination type, both of which are LLVM scalar types.
1340Value *CodeGenFunction::EmitScalarConversion(Value *Src, QualType SrcTy,
1341                                             QualType DstTy) {
1342  assert(!hasAggregateLLVMType(SrcTy) && !hasAggregateLLVMType(DstTy) &&
1343         "Invalid scalar expression to emit");
1344  return ScalarExprEmitter(*this).EmitScalarConversion(Src, SrcTy, DstTy);
1345}
1346
1347/// EmitComplexToScalarConversion - Emit a conversion from the specified
1348/// complex type to the specified destination type, where the destination
1349/// type is an LLVM scalar type.
1350Value *CodeGenFunction::EmitComplexToScalarConversion(ComplexPairTy Src,
1351                                                      QualType SrcTy,
1352                                                      QualType DstTy) {
1353  assert(SrcTy->isAnyComplexType() && !hasAggregateLLVMType(DstTy) &&
1354         "Invalid complex -> scalar conversion");
1355  return ScalarExprEmitter(*this).EmitComplexToScalarConversion(Src, SrcTy,
1356                                                                DstTy);
1357}
1358
1359Value *CodeGenFunction::EmitShuffleVector(Value* V1, Value *V2, ...) {
1360  assert(V1->getType() == V2->getType() &&
1361         "Vector operands must be of the same type");
1362  unsigned NumElements =
1363    cast<llvm::VectorType>(V1->getType())->getNumElements();
1364
1365  va_list va;
1366  va_start(va, V2);
1367
1368  llvm::SmallVector<llvm::Constant*, 16> Args;
1369  for (unsigned i = 0; i < NumElements; i++) {
1370    int n = va_arg(va, int);
1371    assert(n >= 0 && n < (int)NumElements * 2 &&
1372           "Vector shuffle index out of bounds!");
1373    Args.push_back(llvm::ConstantInt::get(llvm::Type::Int32Ty, n));
1374  }
1375
1376  const char *Name = va_arg(va, const char *);
1377  va_end(va);
1378
1379  llvm::Constant *Mask = llvm::ConstantVector::get(&Args[0], NumElements);
1380
1381  return Builder.CreateShuffleVector(V1, V2, Mask, Name);
1382}
1383
1384llvm::Value *CodeGenFunction::EmitVector(llvm::Value * const *Vals,
1385                                         unsigned NumVals, bool isSplat) {
1386  llvm::Value *Vec
1387    = llvm::UndefValue::get(llvm::VectorType::get(Vals[0]->getType(), NumVals));
1388
1389  for (unsigned i = 0, e = NumVals; i != e; ++i) {
1390    llvm::Value *Val = isSplat ? Vals[0] : Vals[i];
1391    llvm::Value *Idx = llvm::ConstantInt::get(llvm::Type::Int32Ty, i);
1392    Vec = Builder.CreateInsertElement(Vec, Val, Idx, "tmp");
1393  }
1394
1395  return Vec;
1396}
1397