CGExprScalar.cpp revision 1522bc80df0a10517bc667c733a918f88dea0b89 
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<llvm::VectorType>(DstTy)->getElementType() == Src->getType())
414    return CGF.EmitVector(&Src, DstType->getAsVectorType()->getNumElements(),
415                          true);
416
417  // Allow bitcast from vector to integer/fp of the same size.
418  if (isa<llvm::VectorType>(Src->getType()) ||
419      isa<llvm::VectorType>(DstTy))
420    return Builder.CreateBitCast(Src, DstTy, "conv");
421
422  // Finally, we have the arithmetic types: real int/float.
423  if (isa<llvm::IntegerType>(Src->getType())) {
424    bool InputSigned = SrcType->isSignedIntegerType();
425    if (isa<llvm::IntegerType>(DstTy))
426      return Builder.CreateIntCast(Src, DstTy, InputSigned, "conv");
427    else if (InputSigned)
428      return Builder.CreateSIToFP(Src, DstTy, "conv");
429    else
430      return Builder.CreateUIToFP(Src, DstTy, "conv");
431  }
432
433  assert(Src->getType()->isFloatingPoint() && "Unknown real conversion");
434  if (isa<llvm::IntegerType>(DstTy)) {
435    if (DstType->isSignedIntegerType())
436      return Builder.CreateFPToSI(Src, DstTy, "conv");
437    else
438      return Builder.CreateFPToUI(Src, DstTy, "conv");
439  }
440
441  assert(DstTy->isFloatingPoint() && "Unknown real conversion");
442  if (DstTy->getTypeID() < Src->getType()->getTypeID())
443    return Builder.CreateFPTrunc(Src, DstTy, "conv");
444  else
445    return Builder.CreateFPExt(Src, DstTy, "conv");
446}
447
448/// EmitComplexToScalarConversion - Emit a conversion from the specified
449/// complex type to the specified destination type, where the destination
450/// type is an LLVM scalar type.
451Value *ScalarExprEmitter::
452EmitComplexToScalarConversion(CodeGenFunction::ComplexPairTy Src,
453                              QualType SrcTy, QualType DstTy) {
454  // Get the source element type.
455  SrcTy = SrcTy->getAsComplexType()->getElementType();
456
457  // Handle conversions to bool first, they are special: comparisons against 0.
458  if (DstTy->isBooleanType()) {
459    //  Complex != 0  -> (Real != 0) | (Imag != 0)
460    Src.first  = EmitScalarConversion(Src.first, SrcTy, DstTy);
461    Src.second = EmitScalarConversion(Src.second, SrcTy, DstTy);
462    return Builder.CreateOr(Src.first, Src.second, "tobool");
463  }
464
465  // C99 6.3.1.7p2: "When a value of complex type is converted to a real type,
466  // the imaginary part of the complex value is discarded and the value of the
467  // real part is converted according to the conversion rules for the
468  // corresponding real type.
469  return EmitScalarConversion(Src.first, SrcTy, DstTy);
470}
471
472
473//===----------------------------------------------------------------------===//
474//                            Visitor Methods
475//===----------------------------------------------------------------------===//
476
477Value *ScalarExprEmitter::VisitExpr(Expr *E) {
478  CGF.ErrorUnsupported(E, "scalar expression");
479  if (E->getType()->isVoidType())
480    return 0;
481  return llvm::UndefValue::get(CGF.ConvertType(E->getType()));
482}
483
484Value *ScalarExprEmitter::VisitShuffleVectorExpr(ShuffleVectorExpr *E) {
485  llvm::SmallVector<llvm::Constant*, 32> indices;
486  for (unsigned i = 2; i < E->getNumSubExprs(); i++) {
487    indices.push_back(cast<llvm::Constant>(CGF.EmitScalarExpr(E->getExpr(i))));
488  }
489  Value* V1 = CGF.EmitScalarExpr(E->getExpr(0));
490  Value* V2 = CGF.EmitScalarExpr(E->getExpr(1));
491  Value* SV = llvm::ConstantVector::get(indices.begin(), indices.size());
492  return Builder.CreateShuffleVector(V1, V2, SV, "shuffle");
493}
494
495Value *ScalarExprEmitter::VisitArraySubscriptExpr(ArraySubscriptExpr *E) {
496  // Emit subscript expressions in rvalue context's.  For most cases, this just
497  // loads the lvalue formed by the subscript expr.  However, we have to be
498  // careful, because the base of a vector subscript is occasionally an rvalue,
499  // so we can't get it as an lvalue.
500  if (!E->getBase()->getType()->isVectorType())
501    return EmitLoadOfLValue(E);
502
503  // Handle the vector case.  The base must be a vector, the index must be an
504  // integer value.
505  Value *Base = Visit(E->getBase());
506  Value *Idx  = Visit(E->getIdx());
507
508  // FIXME: Convert Idx to i32 type.
509  return Builder.CreateExtractElement(Base, Idx, "vecext");
510}
511
512/// VisitImplicitCastExpr - Implicit casts are the same as normal casts, but
513/// also handle things like function to pointer-to-function decay, and array to
514/// pointer decay.
515Value *ScalarExprEmitter::VisitImplicitCastExpr(const ImplicitCastExpr *E) {
516  const Expr *Op = E->getSubExpr();
517
518  // If this is due to array->pointer conversion, emit the array expression as
519  // an l-value.
520  if (Op->getType()->isArrayType()) {
521    // FIXME: For now we assume that all source arrays map to LLVM arrays.  This
522    // will not true when we add support for VLAs.
523    Value *V = EmitLValue(Op).getAddress();  // Bitfields can't be arrays.
524
525    if (!Op->getType()->isVariableArrayType()) {
526      assert(isa<llvm::PointerType>(V->getType()) && "Expected pointer");
527      assert(isa<llvm::ArrayType>(cast<llvm::PointerType>(V->getType())
528                                 ->getElementType()) &&
529             "Expected pointer to array");
530      V = Builder.CreateStructGEP(V, 0, "arraydecay");
531    }
532
533    // The resultant pointer type can be implicitly casted to other pointer
534    // types as well (e.g. void*) and can be implicitly converted to integer.
535    const llvm::Type *DestTy = ConvertType(E->getType());
536    if (V->getType() != DestTy) {
537      if (isa<llvm::PointerType>(DestTy))
538        V = Builder.CreateBitCast(V, DestTy, "ptrconv");
539      else {
540        assert(isa<llvm::IntegerType>(DestTy) && "Unknown array decay");
541        V = Builder.CreatePtrToInt(V, DestTy, "ptrconv");
542      }
543    }
544    return V;
545
546  } else if (E->getType()->isReferenceType()) {
547    return EmitLValue(Op).getAddress();
548  }
549
550  return EmitCastExpr(Op, E->getType());
551}
552
553
554// VisitCastExpr - Emit code for an explicit or implicit cast.  Implicit casts
555// have to handle a more broad range of conversions than explicit casts, as they
556// handle things like function to ptr-to-function decay etc.
557Value *ScalarExprEmitter::EmitCastExpr(const Expr *E, QualType DestTy) {
558  // Handle cases where the source is an non-complex type.
559
560  if (!CGF.hasAggregateLLVMType(E->getType())) {
561    Value *Src = Visit(const_cast<Expr*>(E));
562
563    // Use EmitScalarConversion to perform the conversion.
564    return EmitScalarConversion(Src, E->getType(), DestTy);
565  }
566
567  if (E->getType()->isAnyComplexType()) {
568    // Handle cases where the source is a complex type.
569    return EmitComplexToScalarConversion(CGF.EmitComplexExpr(E), E->getType(),
570                                         DestTy);
571  }
572
573  // Okay, this is a cast from an aggregate.  It must be a cast to void.  Just
574  // evaluate the result and return.
575  CGF.EmitAggExpr(E, 0, false);
576  return 0;
577}
578
579Value *ScalarExprEmitter::VisitStmtExpr(const StmtExpr *E) {
580  return CGF.EmitCompoundStmt(*E->getSubStmt(),
581                              !E->getType()->isVoidType()).getScalarVal();
582}
583
584
585//===----------------------------------------------------------------------===//
586//                             Unary Operators
587//===----------------------------------------------------------------------===//
588
589Value *ScalarExprEmitter::VisitPrePostIncDec(const UnaryOperator *E,
590                                             bool isInc, bool isPre) {
591  LValue LV = EmitLValue(E->getSubExpr());
592  // FIXME: Handle volatile!
593  Value *InVal = CGF.EmitLoadOfLValue(LV, // false
594                                     E->getSubExpr()->getType()).getScalarVal();
595
596  int AmountVal = isInc ? 1 : -1;
597
598  Value *NextVal;
599  if (isa<llvm::PointerType>(InVal->getType())) {
600    // FIXME: This isn't right for VLAs.
601    NextVal = llvm::ConstantInt::get(llvm::Type::Int32Ty, AmountVal);
602    NextVal = Builder.CreateGEP(InVal, NextVal, "ptrincdec");
603  } else {
604    // Add the inc/dec to the real part.
605    if (isa<llvm::IntegerType>(InVal->getType()))
606      NextVal = llvm::ConstantInt::get(InVal->getType(), AmountVal);
607    else if (InVal->getType() == llvm::Type::FloatTy)
608      NextVal =
609        llvm::ConstantFP::get(llvm::APFloat(static_cast<float>(AmountVal)));
610    else if (InVal->getType() == llvm::Type::DoubleTy)
611      NextVal =
612        llvm::ConstantFP::get(llvm::APFloat(static_cast<double>(AmountVal)));
613    else {
614      llvm::APFloat F(static_cast<float>(AmountVal));
615      bool ignored;
616      F.convert(CGF.Target.getLongDoubleFormat(), llvm::APFloat::rmTowardZero,
617                &ignored);
618      NextVal = llvm::ConstantFP::get(F);
619    }
620    NextVal = Builder.CreateAdd(InVal, NextVal, isInc ? "inc" : "dec");
621  }
622
623  // Store the updated result through the lvalue.
624  CGF.EmitStoreThroughLValue(RValue::get(NextVal), LV,
625                             E->getSubExpr()->getType());
626
627  // If this is a postinc, return the value read from memory, otherwise use the
628  // updated value.
629  return isPre ? NextVal : InVal;
630}
631
632
633Value *ScalarExprEmitter::VisitUnaryMinus(const UnaryOperator *E) {
634  Value *Op = Visit(E->getSubExpr());
635  return Builder.CreateNeg(Op, "neg");
636}
637
638Value *ScalarExprEmitter::VisitUnaryNot(const UnaryOperator *E) {
639  Value *Op = Visit(E->getSubExpr());
640  return Builder.CreateNot(Op, "neg");
641}
642
643Value *ScalarExprEmitter::VisitUnaryLNot(const UnaryOperator *E) {
644  // Compare operand to zero.
645  Value *BoolVal = CGF.EvaluateExprAsBool(E->getSubExpr());
646
647  // Invert value.
648  // TODO: Could dynamically modify easy computations here.  For example, if
649  // the operand is an icmp ne, turn into icmp eq.
650  BoolVal = Builder.CreateNot(BoolVal, "lnot");
651
652  // ZExt result to int.
653  return Builder.CreateZExt(BoolVal, CGF.LLVMIntTy, "lnot.ext");
654}
655
656/// VisitSizeOfAlignOfExpr - Return the size or alignment of the type of
657/// argument of the sizeof expression as an integer.
658Value *
659ScalarExprEmitter::VisitSizeOfAlignOfExpr(const SizeOfAlignOfExpr *E) {
660  QualType RetType = E->getType();
661  assert(RetType->isIntegerType() && "Result type must be an integer!");
662  uint32_t ResultWidth =
663    static_cast<uint32_t>(CGF.getContext().getTypeSize(RetType));
664
665  QualType TypeToSize = E->getTypeOfArgument();
666  // sizeof(void) and __alignof__(void) = 1 as a gcc extension. Also
667  // for function types.
668  // FIXME: what is alignof a function type in gcc?
669  if (TypeToSize->isVoidType() || TypeToSize->isFunctionType())
670    return llvm::ConstantInt::get(llvm::APInt(ResultWidth, 1));
671
672  if (const VariableArrayType *VAT =
673        CGF.getContext().getAsVariableArrayType(TypeToSize)) {
674    if (E->isSizeOf()) {
675      if (E->isArgumentType()) {
676        // sizeof(type) - make sure to emit the VLA size.
677        CGF.EmitVLASize(TypeToSize);
678      }
679      return CGF.GetVLASize(VAT);
680    }
681
682    // alignof
683    QualType BaseType = CGF.getContext().getBaseElementType(VAT);
684    uint64_t Align = CGF.getContext().getTypeAlign(BaseType);
685
686    Align /= 8;  // Return alignment in bytes, not bits.
687    return llvm::ConstantInt::get(llvm::APInt(ResultWidth, Align));
688  }
689  if (TypeToSize->isObjCInterfaceType()) {
690    ObjCInterfaceDecl *OI = TypeToSize->getAsObjCInterfaceType()->getDecl();
691    RecordDecl *RD = const_cast<RecordDecl*>(
692                                        CGF.getContext().addRecordToClass(OI));
693    TypeToSize =  CGF.getContext().getTagDeclType(static_cast<TagDecl*>(RD));
694  }
695  std::pair<uint64_t, unsigned> Info = CGF.getContext().getTypeInfo(TypeToSize);
696
697  uint64_t Val = E->isSizeOf() ? Info.first : Info.second;
698  Val /= 8;  // Return size in bytes, not bits.
699
700  return llvm::ConstantInt::get(llvm::APInt(ResultWidth, Val));
701}
702
703Value *ScalarExprEmitter::VisitUnaryReal(const UnaryOperator *E) {
704  Expr *Op = E->getSubExpr();
705  if (Op->getType()->isAnyComplexType())
706    return CGF.EmitComplexExpr(Op).first;
707  return Visit(Op);
708}
709Value *ScalarExprEmitter::VisitUnaryImag(const UnaryOperator *E) {
710  Expr *Op = E->getSubExpr();
711  if (Op->getType()->isAnyComplexType())
712    return CGF.EmitComplexExpr(Op).second;
713
714  // __imag on a scalar returns zero.  Emit it the subexpr to ensure side
715  // effects are evaluated.
716  CGF.EmitScalarExpr(Op);
717  return llvm::Constant::getNullValue(ConvertType(E->getType()));
718}
719
720Value *ScalarExprEmitter::VisitUnaryOffsetOf(const UnaryOperator *E)
721{
722  int64_t Val = E->evaluateOffsetOf(CGF.getContext());
723
724  assert(E->getType()->isIntegerType() && "Result type must be an integer!");
725
726  uint32_t ResultWidth =
727    static_cast<uint32_t>(CGF.getContext().getTypeSize(E->getType()));
728  return llvm::ConstantInt::get(llvm::APInt(ResultWidth, Val));
729}
730
731//===----------------------------------------------------------------------===//
732//                           Binary Operators
733//===----------------------------------------------------------------------===//
734
735BinOpInfo ScalarExprEmitter::EmitBinOps(const BinaryOperator *E) {
736  BinOpInfo Result;
737  Result.LHS = Visit(E->getLHS());
738  Result.RHS = Visit(E->getRHS());
739  Result.Ty  = E->getType();
740  Result.E = E;
741  return Result;
742}
743
744Value *ScalarExprEmitter::EmitCompoundAssign(const CompoundAssignOperator *E,
745                      Value *(ScalarExprEmitter::*Func)(const BinOpInfo &)) {
746  QualType LHSTy = E->getLHS()->getType(), RHSTy = E->getRHS()->getType();
747
748  BinOpInfo OpInfo;
749
750  // Load the LHS and RHS operands.
751  LValue LHSLV = EmitLValue(E->getLHS());
752  OpInfo.LHS = EmitLoadOfLValue(LHSLV, LHSTy);
753
754  // Determine the computation type.  If the RHS is complex, then this is one of
755  // the add/sub/mul/div operators.  All of these operators can be computed in
756  // with just their real component even though the computation domain really is
757  // complex.
758  QualType ComputeType = E->getComputationType();
759
760  // If the computation type is complex, then the RHS is complex.  Emit the RHS.
761  if (const ComplexType *CT = ComputeType->getAsComplexType()) {
762    ComputeType = CT->getElementType();
763
764    // Emit the RHS, only keeping the real component.
765    OpInfo.RHS = CGF.EmitComplexExpr(E->getRHS()).first;
766    RHSTy = RHSTy->getAsComplexType()->getElementType();
767  } else {
768    // Otherwise the RHS is a simple scalar value.
769    OpInfo.RHS = Visit(E->getRHS());
770  }
771
772  QualType LComputeTy, RComputeTy, ResultTy;
773
774  // Compound assignment does not contain enough information about all
775  // the types involved for pointer arithmetic cases. Figure it out
776  // here for now.
777  if (E->getLHS()->getType()->isPointerType()) {
778    // Pointer arithmetic cases: ptr +=,-= int and ptr -= ptr,
779    assert((E->getOpcode() == BinaryOperator::AddAssign ||
780            E->getOpcode() == BinaryOperator::SubAssign) &&
781           "Invalid compound assignment operator on pointer type.");
782    LComputeTy = E->getLHS()->getType();
783
784    if (E->getRHS()->getType()->isPointerType()) {
785      // Degenerate case of (ptr -= ptr) allowed by GCC implicit cast
786      // extension, the conversion from the pointer difference back to
787      // the LHS type is handled at the end.
788      assert(E->getOpcode() == BinaryOperator::SubAssign &&
789             "Invalid compound assignment operator on pointer type.");
790      RComputeTy = E->getLHS()->getType();
791      ResultTy = CGF.getContext().getPointerDiffType();
792    } else {
793      RComputeTy = E->getRHS()->getType();
794      ResultTy = LComputeTy;
795    }
796  } else if (E->getRHS()->getType()->isPointerType()) {
797    // Degenerate case of (int += ptr) allowed by GCC implicit cast
798    // extension.
799    assert(E->getOpcode() == BinaryOperator::AddAssign &&
800           "Invalid compound assignment operator on pointer type.");
801    LComputeTy = E->getLHS()->getType();
802    RComputeTy = E->getRHS()->getType();
803    ResultTy = RComputeTy;
804  } else {
805    LComputeTy = RComputeTy = ResultTy = ComputeType;
806  }
807
808  // Convert the LHS/RHS values to the computation type.
809  OpInfo.LHS = EmitScalarConversion(OpInfo.LHS, LHSTy, LComputeTy);
810  OpInfo.RHS = EmitScalarConversion(OpInfo.RHS, RHSTy, RComputeTy);
811  OpInfo.Ty = ResultTy;
812  OpInfo.E = E;
813
814  // Expand the binary operator.
815  Value *Result = (this->*Func)(OpInfo);
816
817  // Convert the result back to the LHS type.
818  Result = EmitScalarConversion(Result, ResultTy, LHSTy);
819
820  // Store the result value into the LHS lvalue. Bit-fields are
821  // handled specially because the result is altered by the store,
822  // i.e., [C99 6.5.16p1] 'An assignment expression has the value of
823  // the left operand after the assignment...'.
824  if (LHSLV.isBitfield())
825    CGF.EmitStoreThroughBitfieldLValue(RValue::get(Result), LHSLV, LHSTy,
826                                       &Result);
827  else
828    CGF.EmitStoreThroughLValue(RValue::get(Result), LHSLV, LHSTy);
829
830  return Result;
831}
832
833
834Value *ScalarExprEmitter::EmitDiv(const BinOpInfo &Ops) {
835  if (Ops.LHS->getType()->isFPOrFPVector())
836    return Builder.CreateFDiv(Ops.LHS, Ops.RHS, "div");
837  else if (Ops.Ty->isUnsignedIntegerType())
838    return Builder.CreateUDiv(Ops.LHS, Ops.RHS, "div");
839  else
840    return Builder.CreateSDiv(Ops.LHS, Ops.RHS, "div");
841}
842
843Value *ScalarExprEmitter::EmitRem(const BinOpInfo &Ops) {
844  // Rem in C can't be a floating point type: C99 6.5.5p2.
845  if (Ops.Ty->isUnsignedIntegerType())
846    return Builder.CreateURem(Ops.LHS, Ops.RHS, "rem");
847  else
848    return Builder.CreateSRem(Ops.LHS, Ops.RHS, "rem");
849}
850
851
852Value *ScalarExprEmitter::EmitAdd(const BinOpInfo &Ops) {
853  if (!Ops.Ty->isPointerType())
854    return Builder.CreateAdd(Ops.LHS, Ops.RHS, "add");
855
856  // FIXME: What about a pointer to a VLA?
857  Value *Ptr, *Idx;
858  Expr *IdxExp;
859  if (isa<llvm::PointerType>(Ops.LHS->getType())) {  // pointer + int
860    Ptr = Ops.LHS;
861    Idx = Ops.RHS;
862    IdxExp = Ops.E->getRHS();
863  } else {                                           // int + pointer
864    Ptr = Ops.RHS;
865    Idx = Ops.LHS;
866    IdxExp = Ops.E->getLHS();
867  }
868
869  unsigned Width = cast<llvm::IntegerType>(Idx->getType())->getBitWidth();
870  if (Width < CGF.LLVMPointerWidth) {
871    // Zero or sign extend the pointer value based on whether the index is
872    // signed or not.
873    const llvm::Type *IdxType = llvm::IntegerType::get(CGF.LLVMPointerWidth);
874    if (IdxExp->getType()->isSignedIntegerType())
875      Idx = Builder.CreateSExt(Idx, IdxType, "idx.ext");
876    else
877      Idx = Builder.CreateZExt(Idx, IdxType, "idx.ext");
878  }
879
880  return Builder.CreateGEP(Ptr, Idx, "add.ptr");
881}
882
883Value *ScalarExprEmitter::EmitSub(const BinOpInfo &Ops) {
884  if (!isa<llvm::PointerType>(Ops.LHS->getType()))
885    return Builder.CreateSub(Ops.LHS, Ops.RHS, "sub");
886
887  if (!isa<llvm::PointerType>(Ops.RHS->getType())) {
888    // pointer - int
889    Value *Idx = Ops.RHS;
890    unsigned Width = cast<llvm::IntegerType>(Idx->getType())->getBitWidth();
891    if (Width < CGF.LLVMPointerWidth) {
892      // Zero or sign extend the pointer value based on whether the index is
893      // signed or not.
894      const llvm::Type *IdxType = llvm::IntegerType::get(CGF.LLVMPointerWidth);
895      if (Ops.E->getRHS()->getType()->isSignedIntegerType())
896        Idx = Builder.CreateSExt(Idx, IdxType, "idx.ext");
897      else
898        Idx = Builder.CreateZExt(Idx, IdxType, "idx.ext");
899    }
900    Idx = Builder.CreateNeg(Idx, "sub.ptr.neg");
901
902    // FIXME: The pointer could point to a VLA.
903    // The GNU void* - int case is automatically handled here because
904    // our LLVM type for void* is i8*.
905    return Builder.CreateGEP(Ops.LHS, Idx, "sub.ptr");
906  } else {
907    // pointer - pointer
908    Value *LHS = Ops.LHS;
909    Value *RHS = Ops.RHS;
910
911    const QualType LHSType = Ops.E->getLHS()->getType();
912    const QualType LHSElementType = LHSType->getAsPointerType()->getPointeeType();
913    uint64_t ElementSize;
914
915    // Handle GCC extension for pointer arithmetic on void* types.
916    if (LHSElementType->isVoidType()) {
917      ElementSize = 1;
918    } else {
919      ElementSize = CGF.getContext().getTypeSize(LHSElementType) / 8;
920    }
921
922    const llvm::Type *ResultType = ConvertType(Ops.Ty);
923    LHS = Builder.CreatePtrToInt(LHS, ResultType, "sub.ptr.lhs.cast");
924    RHS = Builder.CreatePtrToInt(RHS, ResultType, "sub.ptr.rhs.cast");
925    Value *BytesBetween = Builder.CreateSub(LHS, RHS, "sub.ptr.sub");
926
927    // HACK: LLVM doesn't have an divide instruction that 'knows' there is no
928    // remainder.  As such, we handle common power-of-two cases here to generate
929    // better code. See PR2247.
930    if (llvm::isPowerOf2_64(ElementSize)) {
931      Value *ShAmt =
932        llvm::ConstantInt::get(ResultType, llvm::Log2_64(ElementSize));
933      return Builder.CreateAShr(BytesBetween, ShAmt, "sub.ptr.shr");
934    }
935
936    // Otherwise, do a full sdiv.
937    Value *BytesPerElt = llvm::ConstantInt::get(ResultType, ElementSize);
938    return Builder.CreateSDiv(BytesBetween, BytesPerElt, "sub.ptr.div");
939  }
940}
941
942Value *ScalarExprEmitter::EmitShl(const BinOpInfo &Ops) {
943  // LLVM requires the LHS and RHS to be the same type: promote or truncate the
944  // RHS to the same size as the LHS.
945  Value *RHS = Ops.RHS;
946  if (Ops.LHS->getType() != RHS->getType())
947    RHS = Builder.CreateIntCast(RHS, Ops.LHS->getType(), false, "sh_prom");
948
949  return Builder.CreateShl(Ops.LHS, RHS, "shl");
950}
951
952Value *ScalarExprEmitter::EmitShr(const BinOpInfo &Ops) {
953  // LLVM requires the LHS and RHS to be the same type: promote or truncate the
954  // RHS to the same size as the LHS.
955  Value *RHS = Ops.RHS;
956  if (Ops.LHS->getType() != RHS->getType())
957    RHS = Builder.CreateIntCast(RHS, Ops.LHS->getType(), false, "sh_prom");
958
959  if (Ops.Ty->isUnsignedIntegerType())
960    return Builder.CreateLShr(Ops.LHS, RHS, "shr");
961  return Builder.CreateAShr(Ops.LHS, RHS, "shr");
962}
963
964Value *ScalarExprEmitter::EmitCompare(const BinaryOperator *E,unsigned UICmpOpc,
965                                      unsigned SICmpOpc, unsigned FCmpOpc) {
966  Value *Result;
967  QualType LHSTy = E->getLHS()->getType();
968  if (!LHSTy->isAnyComplexType() && !LHSTy->isVectorType()) {
969    Value *LHS = Visit(E->getLHS());
970    Value *RHS = Visit(E->getRHS());
971
972    if (LHS->getType()->isFloatingPoint()) {
973      Result = Builder.CreateFCmp((llvm::CmpInst::Predicate)FCmpOpc,
974                                  LHS, RHS, "cmp");
975    } else if (LHSTy->isSignedIntegerType()) {
976      Result = Builder.CreateICmp((llvm::ICmpInst::Predicate)SICmpOpc,
977                                  LHS, RHS, "cmp");
978    } else {
979      // Unsigned integers and pointers.
980      Result = Builder.CreateICmp((llvm::ICmpInst::Predicate)UICmpOpc,
981                                  LHS, RHS, "cmp");
982    }
983  } else if (LHSTy->isVectorType()) {
984    Value *LHS = Visit(E->getLHS());
985    Value *RHS = Visit(E->getRHS());
986
987    if (LHS->getType()->isFPOrFPVector()) {
988      Result = Builder.CreateVFCmp((llvm::CmpInst::Predicate)FCmpOpc,
989                                  LHS, RHS, "cmp");
990    } else if (LHSTy->isUnsignedIntegerType()) {
991      Result = Builder.CreateVICmp((llvm::CmpInst::Predicate)UICmpOpc,
992                                  LHS, RHS, "cmp");
993    } else {
994      // Signed integers and pointers.
995      Result = Builder.CreateVICmp((llvm::CmpInst::Predicate)SICmpOpc,
996                                  LHS, RHS, "cmp");
997    }
998    return Result;
999  } else {
1000    // Complex Comparison: can only be an equality comparison.
1001    CodeGenFunction::ComplexPairTy LHS = CGF.EmitComplexExpr(E->getLHS());
1002    CodeGenFunction::ComplexPairTy RHS = CGF.EmitComplexExpr(E->getRHS());
1003
1004    QualType CETy = LHSTy->getAsComplexType()->getElementType();
1005
1006    Value *ResultR, *ResultI;
1007    if (CETy->isRealFloatingType()) {
1008      ResultR = Builder.CreateFCmp((llvm::FCmpInst::Predicate)FCmpOpc,
1009                                   LHS.first, RHS.first, "cmp.r");
1010      ResultI = Builder.CreateFCmp((llvm::FCmpInst::Predicate)FCmpOpc,
1011                                   LHS.second, RHS.second, "cmp.i");
1012    } else {
1013      // Complex comparisons can only be equality comparisons.  As such, signed
1014      // and unsigned opcodes are the same.
1015      ResultR = Builder.CreateICmp((llvm::ICmpInst::Predicate)UICmpOpc,
1016                                   LHS.first, RHS.first, "cmp.r");
1017      ResultI = Builder.CreateICmp((llvm::ICmpInst::Predicate)UICmpOpc,
1018                                   LHS.second, RHS.second, "cmp.i");
1019    }
1020
1021    if (E->getOpcode() == BinaryOperator::EQ) {
1022      Result = Builder.CreateAnd(ResultR, ResultI, "and.ri");
1023    } else {
1024      assert(E->getOpcode() == BinaryOperator::NE &&
1025             "Complex comparison other than == or != ?");
1026      Result = Builder.CreateOr(ResultR, ResultI, "or.ri");
1027    }
1028  }
1029
1030  return EmitScalarConversion(Result, CGF.getContext().BoolTy, E->getType());
1031}
1032
1033Value *ScalarExprEmitter::VisitBinAssign(const BinaryOperator *E) {
1034  LValue LHS = EmitLValue(E->getLHS());
1035  Value *RHS = Visit(E->getRHS());
1036
1037  // Store the value into the LHS.  Bit-fields are handled specially
1038  // because the result is altered by the store, i.e., [C99 6.5.16p1]
1039  // 'An assignment expression has the value of the left operand after
1040  // the assignment...'.
1041  // FIXME: Volatility!
1042  if (LHS.isBitfield())
1043    CGF.EmitStoreThroughBitfieldLValue(RValue::get(RHS), LHS, E->getType(),
1044                                       &RHS);
1045  else
1046    CGF.EmitStoreThroughLValue(RValue::get(RHS), LHS, E->getType());
1047
1048  // Return the RHS.
1049  return RHS;
1050}
1051
1052Value *ScalarExprEmitter::VisitBinLAnd(const BinaryOperator *E) {
1053  // If we have 0 && RHS, see if we can elide RHS, if so, just return 0.
1054  // If we have 1 && X, just emit X without inserting the control flow.
1055  if (int Cond = CGF.ConstantFoldsToSimpleInteger(E->getLHS())) {
1056    if (Cond == 1) { // If we have 1 && X, just emit X.
1057      Value *RHSCond = CGF.EvaluateExprAsBool(E->getRHS());
1058      // ZExt result to int.
1059      return Builder.CreateZExt(RHSCond, CGF.LLVMIntTy, "land.ext");
1060    }
1061
1062    // 0 && RHS: If it is safe, just elide the RHS, and return 0.
1063    if (!CGF.ContainsLabel(E->getRHS()))
1064      return llvm::Constant::getNullValue(CGF.LLVMIntTy);
1065  }
1066
1067  llvm::BasicBlock *ContBlock = CGF.createBasicBlock("land.end");
1068  llvm::BasicBlock *RHSBlock  = CGF.createBasicBlock("land.rhs");
1069
1070  // Branch on the LHS first.  If it is false, go to the failure (cont) block.
1071  CGF.EmitBranchOnBoolExpr(E->getLHS(), RHSBlock, ContBlock);
1072
1073  // Any edges into the ContBlock are now from an (indeterminate number of)
1074  // edges from this first condition.  All of these values will be false.  Start
1075  // setting up the PHI node in the Cont Block for this.
1076  llvm::PHINode *PN = llvm::PHINode::Create(llvm::Type::Int1Ty, "", ContBlock);
1077  PN->reserveOperandSpace(2);  // Normal case, two inputs.
1078  for (llvm::pred_iterator PI = pred_begin(ContBlock), PE = pred_end(ContBlock);
1079       PI != PE; ++PI)
1080    PN->addIncoming(llvm::ConstantInt::getFalse(), *PI);
1081
1082  CGF.EmitBlock(RHSBlock);
1083  Value *RHSCond = CGF.EvaluateExprAsBool(E->getRHS());
1084
1085  // Reaquire the RHS block, as there may be subblocks inserted.
1086  RHSBlock = Builder.GetInsertBlock();
1087
1088  // Emit an unconditional branch from this block to ContBlock.  Insert an entry
1089  // into the phi node for the edge with the value of RHSCond.
1090  CGF.EmitBlock(ContBlock);
1091  PN->addIncoming(RHSCond, RHSBlock);
1092
1093  // ZExt result to int.
1094  return Builder.CreateZExt(PN, CGF.LLVMIntTy, "land.ext");
1095}
1096
1097Value *ScalarExprEmitter::VisitBinLOr(const BinaryOperator *E) {
1098  // If we have 1 || RHS, see if we can elide RHS, if so, just return 1.
1099  // If we have 0 || X, just emit X without inserting the control flow.
1100  if (int Cond = CGF.ConstantFoldsToSimpleInteger(E->getLHS())) {
1101    if (Cond == -1) { // If we have 0 || X, just emit X.
1102      Value *RHSCond = CGF.EvaluateExprAsBool(E->getRHS());
1103      // ZExt result to int.
1104      return Builder.CreateZExt(RHSCond, CGF.LLVMIntTy, "lor.ext");
1105    }
1106
1107    // 1 || RHS: If it is safe, just elide the RHS, and return 1.
1108    if (!CGF.ContainsLabel(E->getRHS()))
1109      return llvm::ConstantInt::get(CGF.LLVMIntTy, 1);
1110  }
1111
1112  llvm::BasicBlock *ContBlock = CGF.createBasicBlock("lor.end");
1113  llvm::BasicBlock *RHSBlock = CGF.createBasicBlock("lor.rhs");
1114
1115  // Branch on the LHS first.  If it is true, go to the success (cont) block.
1116  CGF.EmitBranchOnBoolExpr(E->getLHS(), ContBlock, RHSBlock);
1117
1118  // Any edges into the ContBlock are now from an (indeterminate number of)
1119  // edges from this first condition.  All of these values will be true.  Start
1120  // setting up the PHI node in the Cont Block for this.
1121  llvm::PHINode *PN = llvm::PHINode::Create(llvm::Type::Int1Ty, "", ContBlock);
1122  PN->reserveOperandSpace(2);  // Normal case, two inputs.
1123  for (llvm::pred_iterator PI = pred_begin(ContBlock), PE = pred_end(ContBlock);
1124       PI != PE; ++PI)
1125    PN->addIncoming(llvm::ConstantInt::getTrue(), *PI);
1126
1127  // Emit the RHS condition as a bool value.
1128  CGF.EmitBlock(RHSBlock);
1129  Value *RHSCond = CGF.EvaluateExprAsBool(E->getRHS());
1130
1131  // Reaquire the RHS block, as there may be subblocks inserted.
1132  RHSBlock = Builder.GetInsertBlock();
1133
1134  // Emit an unconditional branch from this block to ContBlock.  Insert an entry
1135  // into the phi node for the edge with the value of RHSCond.
1136  CGF.EmitBlock(ContBlock);
1137  PN->addIncoming(RHSCond, RHSBlock);
1138
1139  // ZExt result to int.
1140  return Builder.CreateZExt(PN, CGF.LLVMIntTy, "lor.ext");
1141}
1142
1143Value *ScalarExprEmitter::VisitBinComma(const BinaryOperator *E) {
1144  CGF.EmitStmt(E->getLHS());
1145  CGF.EnsureInsertPoint();
1146  return Visit(E->getRHS());
1147}
1148
1149//===----------------------------------------------------------------------===//
1150//                             Other Operators
1151//===----------------------------------------------------------------------===//
1152
1153/// isCheapEnoughToEvaluateUnconditionally - Return true if the specified
1154/// expression is cheap enough and side-effect-free enough to evaluate
1155/// unconditionally instead of conditionally.  This is used to convert control
1156/// flow into selects in some cases.
1157static bool isCheapEnoughToEvaluateUnconditionally(const Expr *E) {
1158  if (const ParenExpr *PE = dyn_cast<ParenExpr>(E))
1159    return isCheapEnoughToEvaluateUnconditionally(PE->getSubExpr());
1160
1161  // TODO: Allow anything we can constant fold to an integer or fp constant.
1162  if (isa<IntegerLiteral>(E) || isa<CharacterLiteral>(E) ||
1163      isa<FloatingLiteral>(E))
1164    return true;
1165
1166  // Non-volatile automatic variables too, to get "cond ? X : Y" where
1167  // X and Y are local variables.
1168  if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
1169    if (const VarDecl *VD = dyn_cast<VarDecl>(DRE->getDecl()))
1170      if (VD->hasLocalStorage() && !VD->getType().isVolatileQualified())
1171        return true;
1172
1173  return false;
1174}
1175
1176
1177Value *ScalarExprEmitter::
1178VisitConditionalOperator(const ConditionalOperator *E) {
1179  // If the condition constant folds and can be elided, try to avoid emitting
1180  // the condition and the dead arm.
1181  if (int Cond = CGF.ConstantFoldsToSimpleInteger(E->getCond())){
1182    Expr *Live = E->getLHS(), *Dead = E->getRHS();
1183    if (Cond == -1)
1184      std::swap(Live, Dead);
1185
1186    // If the dead side doesn't have labels we need, and if the Live side isn't
1187    // the gnu missing ?: extension (which we could handle, but don't bother
1188    // to), just emit the Live part.
1189    if ((!Dead || !CGF.ContainsLabel(Dead)) &&  // No labels in dead part
1190        Live)                                   // Live part isn't missing.
1191      return Visit(Live);
1192  }
1193
1194
1195  // If this is a really simple expression (like x ? 4 : 5), emit this as a
1196  // select instead of as control flow.  We can only do this if it is cheap and
1197  // safe to evaluate the LHS and RHS unconditionally.
1198  if (E->getLHS() && isCheapEnoughToEvaluateUnconditionally(E->getLHS()) &&
1199      isCheapEnoughToEvaluateUnconditionally(E->getRHS())) {
1200    llvm::Value *CondV = CGF.EvaluateExprAsBool(E->getCond());
1201    llvm::Value *LHS = Visit(E->getLHS());
1202    llvm::Value *RHS = Visit(E->getRHS());
1203    return Builder.CreateSelect(CondV, LHS, RHS, "cond");
1204  }
1205
1206
1207  llvm::BasicBlock *LHSBlock = CGF.createBasicBlock("cond.true");
1208  llvm::BasicBlock *RHSBlock = CGF.createBasicBlock("cond.false");
1209  llvm::BasicBlock *ContBlock = CGF.createBasicBlock("cond.end");
1210  Value *CondVal = 0;
1211
1212  // If we have the GNU missing condition extension, evaluate the conditional
1213  // and then convert it to bool the hard way.  We do this explicitly
1214  // because we need the unconverted value for the missing middle value of
1215  // the ?:.
1216  if (E->getLHS() == 0) {
1217    CondVal = CGF.EmitScalarExpr(E->getCond());
1218    Value *CondBoolVal =
1219      CGF.EmitScalarConversion(CondVal, E->getCond()->getType(),
1220                               CGF.getContext().BoolTy);
1221    Builder.CreateCondBr(CondBoolVal, LHSBlock, RHSBlock);
1222  } else {
1223    // Otherwise, just use EmitBranchOnBoolExpr to get small and simple code for
1224    // the branch on bool.
1225    CGF.EmitBranchOnBoolExpr(E->getCond(), LHSBlock, RHSBlock);
1226  }
1227
1228  CGF.EmitBlock(LHSBlock);
1229
1230  // Handle the GNU extension for missing LHS.
1231  Value *LHS;
1232  if (E->getLHS())
1233    LHS = Visit(E->getLHS());
1234  else    // Perform promotions, to handle cases like "short ?: int"
1235    LHS = EmitScalarConversion(CondVal, E->getCond()->getType(), E->getType());
1236
1237  LHSBlock = Builder.GetInsertBlock();
1238  CGF.EmitBranch(ContBlock);
1239
1240  CGF.EmitBlock(RHSBlock);
1241
1242  Value *RHS = Visit(E->getRHS());
1243  RHSBlock = Builder.GetInsertBlock();
1244  CGF.EmitBranch(ContBlock);
1245
1246  CGF.EmitBlock(ContBlock);
1247
1248  if (!LHS || !RHS) {
1249    assert(E->getType()->isVoidType() && "Non-void value should have a value");
1250    return 0;
1251  }
1252
1253  // Create a PHI node for the real part.
1254  llvm::PHINode *PN = Builder.CreatePHI(LHS->getType(), "cond");
1255  PN->reserveOperandSpace(2);
1256  PN->addIncoming(LHS, LHSBlock);
1257  PN->addIncoming(RHS, RHSBlock);
1258  return PN;
1259}
1260
1261Value *ScalarExprEmitter::VisitChooseExpr(ChooseExpr *E) {
1262  // Emit the LHS or RHS as appropriate.
1263  return
1264    Visit(E->isConditionTrue(CGF.getContext()) ? E->getLHS() : E->getRHS());
1265}
1266
1267Value *ScalarExprEmitter::VisitOverloadExpr(OverloadExpr *E) {
1268  return CGF.EmitCallExpr(E->getFn(), E->arg_begin(),
1269                          E->arg_end(CGF.getContext())).getScalarVal();
1270}
1271
1272Value *ScalarExprEmitter::VisitVAArgExpr(VAArgExpr *VE) {
1273  llvm::Value *ArgValue = EmitLValue(VE->getSubExpr()).getAddress();
1274
1275  llvm::Value *ArgPtr = CGF.EmitVAArg(ArgValue, VE->getType());
1276
1277  // If EmitVAArg fails, we fall back to the LLVM instruction.
1278  if (!ArgPtr)
1279    return Builder.CreateVAArg(ArgValue, ConvertType(VE->getType()));
1280
1281  // FIXME: volatile?
1282  return Builder.CreateLoad(ArgPtr);
1283}
1284
1285Value *ScalarExprEmitter::VisitObjCEncodeExpr(const ObjCEncodeExpr *E) {
1286  std::string str;
1287  CGF.getContext().getObjCEncodingForType(E->getEncodedType(), str);
1288
1289  llvm::Constant *C = llvm::ConstantArray::get(str);
1290  C = new llvm::GlobalVariable(C->getType(), true,
1291                               llvm::GlobalValue::InternalLinkage,
1292                               C, ".str", &CGF.CGM.getModule());
1293  llvm::Constant *Zero = llvm::Constant::getNullValue(llvm::Type::Int32Ty);
1294  llvm::Constant *Zeros[] = { Zero, Zero };
1295  C = llvm::ConstantExpr::getGetElementPtr(C, Zeros, 2);
1296
1297  return C;
1298}
1299
1300//===----------------------------------------------------------------------===//
1301//                         Entry Point into this File
1302//===----------------------------------------------------------------------===//
1303
1304/// EmitComplexExpr - Emit the computation of the specified expression of
1305/// complex type, ignoring the result.
1306Value *CodeGenFunction::EmitScalarExpr(const Expr *E) {
1307  assert(E && !hasAggregateLLVMType(E->getType()) &&
1308         "Invalid scalar expression to emit");
1309
1310  return ScalarExprEmitter(*this).Visit(const_cast<Expr*>(E));
1311}
1312
1313/// EmitScalarConversion - Emit a conversion from the specified type to the
1314/// specified destination type, both of which are LLVM scalar types.
1315Value *CodeGenFunction::EmitScalarConversion(Value *Src, QualType SrcTy,
1316                                             QualType DstTy) {
1317  assert(!hasAggregateLLVMType(SrcTy) && !hasAggregateLLVMType(DstTy) &&
1318         "Invalid scalar expression to emit");
1319  return ScalarExprEmitter(*this).EmitScalarConversion(Src, SrcTy, DstTy);
1320}
1321
1322/// EmitComplexToScalarConversion - Emit a conversion from the specified
1323/// complex type to the specified destination type, where the destination
1324/// type is an LLVM scalar type.
1325Value *CodeGenFunction::EmitComplexToScalarConversion(ComplexPairTy Src,
1326                                                      QualType SrcTy,
1327                                                      QualType DstTy) {
1328  assert(SrcTy->isAnyComplexType() && !hasAggregateLLVMType(DstTy) &&
1329         "Invalid complex -> scalar conversion");
1330  return ScalarExprEmitter(*this).EmitComplexToScalarConversion(Src, SrcTy,
1331                                                                DstTy);
1332}
1333
1334Value *CodeGenFunction::EmitShuffleVector(Value* V1, Value *V2, ...) {
1335  assert(V1->getType() == V2->getType() &&
1336         "Vector operands must be of the same type");
1337  unsigned NumElements =
1338    cast<llvm::VectorType>(V1->getType())->getNumElements();
1339
1340  va_list va;
1341  va_start(va, V2);
1342
1343  llvm::SmallVector<llvm::Constant*, 16> Args;
1344  for (unsigned i = 0; i < NumElements; i++) {
1345    int n = va_arg(va, int);
1346    assert(n >= 0 && n < (int)NumElements * 2 &&
1347           "Vector shuffle index out of bounds!");
1348    Args.push_back(llvm::ConstantInt::get(llvm::Type::Int32Ty, n));
1349  }
1350
1351  const char *Name = va_arg(va, const char *);
1352  va_end(va);
1353
1354  llvm::Constant *Mask = llvm::ConstantVector::get(&Args[0], NumElements);
1355
1356  return Builder.CreateShuffleVector(V1, V2, Mask, Name);
1357}
1358
1359llvm::Value *CodeGenFunction::EmitVector(llvm::Value * const *Vals,
1360                                         unsigned NumVals, bool isSplat) {
1361  llvm::Value *Vec
1362    = llvm::UndefValue::get(llvm::VectorType::get(Vals[0]->getType(), NumVals));
1363
1364  for (unsigned i = 0, e = NumVals; i != e; ++i) {
1365    llvm::Value *Val = isSplat ? Vals[0] : Vals[i];
1366    llvm::Value *Idx = llvm::ConstantInt::get(llvm::Type::Int32Ty, i);
1367    Vec = Builder.CreateInsertElement(Vec, Val, Idx, "tmp");
1368  }
1369
1370  return Vec;
1371}
1372