CodeGenFunction.cpp revision 249423 
1//===--- CodeGenFunction.cpp - Emit LLVM Code from ASTs for a Function ----===//
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 coordinates the per-function state used while generating code.
11//
12//===----------------------------------------------------------------------===//
13
14#include "CodeGenFunction.h"
15#include "CGCUDARuntime.h"
16#include "CGCXXABI.h"
17#include "CGDebugInfo.h"
18#include "CodeGenModule.h"
19#include "clang/AST/ASTContext.h"
20#include "clang/AST/Decl.h"
21#include "clang/AST/DeclCXX.h"
22#include "clang/AST/StmtCXX.h"
23#include "clang/Basic/OpenCL.h"
24#include "clang/Basic/TargetInfo.h"
25#include "clang/Frontend/CodeGenOptions.h"
26#include "llvm/IR/DataLayout.h"
27#include "llvm/IR/Intrinsics.h"
28#include "llvm/IR/MDBuilder.h"
29#include "llvm/IR/Operator.h"
30using namespace clang;
31using namespace CodeGen;
32
33CodeGenFunction::CodeGenFunction(CodeGenModule &cgm, bool suppressNewContext)
34  : CodeGenTypeCache(cgm), CGM(cgm),
35    Target(CGM.getContext().getTargetInfo()),
36    Builder(cgm.getModule().getContext()),
37    SanitizePerformTypeCheck(CGM.getSanOpts().Null |
38                             CGM.getSanOpts().Alignment |
39                             CGM.getSanOpts().ObjectSize |
40                             CGM.getSanOpts().Vptr),
41    SanOpts(&CGM.getSanOpts()),
42    AutoreleaseResult(false), BlockInfo(0), BlockPointer(0),
43    LambdaThisCaptureField(0), NormalCleanupDest(0), NextCleanupDestIndex(1),
44    FirstBlockInfo(0), EHResumeBlock(0), ExceptionSlot(0), EHSelectorSlot(0),
45    DebugInfo(0), DisableDebugInfo(false), CalleeWithThisReturn(0),
46    DidCallStackSave(false),
47    IndirectBranch(0), SwitchInsn(0), CaseRangeBlock(0), UnreachableBlock(0),
48    CXXABIThisDecl(0), CXXABIThisValue(0), CXXThisValue(0),
49    CXXStructorImplicitParamDecl(0), CXXStructorImplicitParamValue(0),
50    OutermostConditional(0), CurLexicalScope(0), TerminateLandingPad(0),
51    TerminateHandler(0), TrapBB(0) {
52  if (!suppressNewContext)
53    CGM.getCXXABI().getMangleContext().startNewFunction();
54
55  llvm::FastMathFlags FMF;
56  if (CGM.getLangOpts().FastMath)
57    FMF.setUnsafeAlgebra();
58  if (CGM.getLangOpts().FiniteMathOnly) {
59    FMF.setNoNaNs();
60    FMF.setNoInfs();
61  }
62  Builder.SetFastMathFlags(FMF);
63}
64
65CodeGenFunction::~CodeGenFunction() {
66  // If there are any unclaimed block infos, go ahead and destroy them
67  // now.  This can happen if IR-gen gets clever and skips evaluating
68  // something.
69  if (FirstBlockInfo)
70    destroyBlockInfos(FirstBlockInfo);
71}
72
73
74llvm::Type *CodeGenFunction::ConvertTypeForMem(QualType T) {
75  return CGM.getTypes().ConvertTypeForMem(T);
76}
77
78llvm::Type *CodeGenFunction::ConvertType(QualType T) {
79  return CGM.getTypes().ConvertType(T);
80}
81
82TypeEvaluationKind CodeGenFunction::getEvaluationKind(QualType type) {
83  type = type.getCanonicalType();
84  while (true) {
85    switch (type->getTypeClass()) {
86#define TYPE(name, parent)
87#define ABSTRACT_TYPE(name, parent)
88#define NON_CANONICAL_TYPE(name, parent) case Type::name:
89#define DEPENDENT_TYPE(name, parent) case Type::name:
90#define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(name, parent) case Type::name:
91#include "clang/AST/TypeNodes.def"
92      llvm_unreachable("non-canonical or dependent type in IR-generation");
93
94    // Various scalar types.
95    case Type::Builtin:
96    case Type::Pointer:
97    case Type::BlockPointer:
98    case Type::LValueReference:
99    case Type::RValueReference:
100    case Type::MemberPointer:
101    case Type::Vector:
102    case Type::ExtVector:
103    case Type::FunctionProto:
104    case Type::FunctionNoProto:
105    case Type::Enum:
106    case Type::ObjCObjectPointer:
107      return TEK_Scalar;
108
109    // Complexes.
110    case Type::Complex:
111      return TEK_Complex;
112
113    // Arrays, records, and Objective-C objects.
114    case Type::ConstantArray:
115    case Type::IncompleteArray:
116    case Type::VariableArray:
117    case Type::Record:
118    case Type::ObjCObject:
119    case Type::ObjCInterface:
120      return TEK_Aggregate;
121
122    // We operate on atomic values according to their underlying type.
123    case Type::Atomic:
124      type = cast<AtomicType>(type)->getValueType();
125      continue;
126    }
127    llvm_unreachable("unknown type kind!");
128  }
129}
130
131void CodeGenFunction::EmitReturnBlock() {
132  // For cleanliness, we try to avoid emitting the return block for
133  // simple cases.
134  llvm::BasicBlock *CurBB = Builder.GetInsertBlock();
135
136  if (CurBB) {
137    assert(!CurBB->getTerminator() && "Unexpected terminated block.");
138
139    // We have a valid insert point, reuse it if it is empty or there are no
140    // explicit jumps to the return block.
141    if (CurBB->empty() || ReturnBlock.getBlock()->use_empty()) {
142      ReturnBlock.getBlock()->replaceAllUsesWith(CurBB);
143      delete ReturnBlock.getBlock();
144    } else
145      EmitBlock(ReturnBlock.getBlock());
146    return;
147  }
148
149  // Otherwise, if the return block is the target of a single direct
150  // branch then we can just put the code in that block instead. This
151  // cleans up functions which started with a unified return block.
152  if (ReturnBlock.getBlock()->hasOneUse()) {
153    llvm::BranchInst *BI =
154      dyn_cast<llvm::BranchInst>(*ReturnBlock.getBlock()->use_begin());
155    if (BI && BI->isUnconditional() &&
156        BI->getSuccessor(0) == ReturnBlock.getBlock()) {
157      // Reset insertion point, including debug location, and delete the
158      // branch.  This is really subtle and only works because the next change
159      // in location will hit the caching in CGDebugInfo::EmitLocation and not
160      // override this.
161      Builder.SetCurrentDebugLocation(BI->getDebugLoc());
162      Builder.SetInsertPoint(BI->getParent());
163      BI->eraseFromParent();
164      delete ReturnBlock.getBlock();
165      return;
166    }
167  }
168
169  // FIXME: We are at an unreachable point, there is no reason to emit the block
170  // unless it has uses. However, we still need a place to put the debug
171  // region.end for now.
172
173  EmitBlock(ReturnBlock.getBlock());
174}
175
176static void EmitIfUsed(CodeGenFunction &CGF, llvm::BasicBlock *BB) {
177  if (!BB) return;
178  if (!BB->use_empty())
179    return CGF.CurFn->getBasicBlockList().push_back(BB);
180  delete BB;
181}
182
183void CodeGenFunction::FinishFunction(SourceLocation EndLoc) {
184  assert(BreakContinueStack.empty() &&
185         "mismatched push/pop in break/continue stack!");
186
187  if (CGDebugInfo *DI = getDebugInfo())
188    DI->EmitLocation(Builder, EndLoc);
189
190  // Pop any cleanups that might have been associated with the
191  // parameters.  Do this in whatever block we're currently in; it's
192  // important to do this before we enter the return block or return
193  // edges will be *really* confused.
194  if (EHStack.stable_begin() != PrologueCleanupDepth)
195    PopCleanupBlocks(PrologueCleanupDepth);
196
197  // Emit function epilog (to return).
198  EmitReturnBlock();
199
200  if (ShouldInstrumentFunction())
201    EmitFunctionInstrumentation("__cyg_profile_func_exit");
202
203  // Emit debug descriptor for function end.
204  if (CGDebugInfo *DI = getDebugInfo()) {
205    DI->EmitFunctionEnd(Builder);
206  }
207
208  EmitFunctionEpilog(*CurFnInfo);
209  EmitEndEHSpec(CurCodeDecl);
210
211  assert(EHStack.empty() &&
212         "did not remove all scopes from cleanup stack!");
213
214  // If someone did an indirect goto, emit the indirect goto block at the end of
215  // the function.
216  if (IndirectBranch) {
217    EmitBlock(IndirectBranch->getParent());
218    Builder.ClearInsertionPoint();
219  }
220
221  // Remove the AllocaInsertPt instruction, which is just a convenience for us.
222  llvm::Instruction *Ptr = AllocaInsertPt;
223  AllocaInsertPt = 0;
224  Ptr->eraseFromParent();
225
226  // If someone took the address of a label but never did an indirect goto, we
227  // made a zero entry PHI node, which is illegal, zap it now.
228  if (IndirectBranch) {
229    llvm::PHINode *PN = cast<llvm::PHINode>(IndirectBranch->getAddress());
230    if (PN->getNumIncomingValues() == 0) {
231      PN->replaceAllUsesWith(llvm::UndefValue::get(PN->getType()));
232      PN->eraseFromParent();
233    }
234  }
235
236  EmitIfUsed(*this, EHResumeBlock);
237  EmitIfUsed(*this, TerminateLandingPad);
238  EmitIfUsed(*this, TerminateHandler);
239  EmitIfUsed(*this, UnreachableBlock);
240
241  if (CGM.getCodeGenOpts().EmitDeclMetadata)
242    EmitDeclMetadata();
243}
244
245/// ShouldInstrumentFunction - Return true if the current function should be
246/// instrumented with __cyg_profile_func_* calls
247bool CodeGenFunction::ShouldInstrumentFunction() {
248  if (!CGM.getCodeGenOpts().InstrumentFunctions)
249    return false;
250  if (!CurFuncDecl || CurFuncDecl->hasAttr<NoInstrumentFunctionAttr>())
251    return false;
252  return true;
253}
254
255/// EmitFunctionInstrumentation - Emit LLVM code to call the specified
256/// instrumentation function with the current function and the call site, if
257/// function instrumentation is enabled.
258void CodeGenFunction::EmitFunctionInstrumentation(const char *Fn) {
259  // void __cyg_profile_func_{enter,exit} (void *this_fn, void *call_site);
260  llvm::PointerType *PointerTy = Int8PtrTy;
261  llvm::Type *ProfileFuncArgs[] = { PointerTy, PointerTy };
262  llvm::FunctionType *FunctionTy =
263    llvm::FunctionType::get(VoidTy, ProfileFuncArgs, false);
264
265  llvm::Constant *F = CGM.CreateRuntimeFunction(FunctionTy, Fn);
266  llvm::CallInst *CallSite = Builder.CreateCall(
267    CGM.getIntrinsic(llvm::Intrinsic::returnaddress),
268    llvm::ConstantInt::get(Int32Ty, 0),
269    "callsite");
270
271  llvm::Value *args[] = {
272    llvm::ConstantExpr::getBitCast(CurFn, PointerTy),
273    CallSite
274  };
275
276  EmitNounwindRuntimeCall(F, args);
277}
278
279void CodeGenFunction::EmitMCountInstrumentation() {
280  llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false);
281
282  llvm::Constant *MCountFn = CGM.CreateRuntimeFunction(FTy,
283                                                       Target.getMCountName());
284  EmitNounwindRuntimeCall(MCountFn);
285}
286
287// OpenCL v1.2 s5.6.4.6 allows the compiler to store kernel argument
288// information in the program executable. The argument information stored
289// includes the argument name, its type, the address and access qualifiers used.
290static void GenOpenCLArgMetadata(const FunctionDecl *FD, llvm::Function *Fn,
291                                 CodeGenModule &CGM,llvm::LLVMContext &Context,
292                                 SmallVector <llvm::Value*, 5> &kernelMDArgs,
293                                 CGBuilderTy& Builder, ASTContext &ASTCtx) {
294  // Create MDNodes that represent the kernel arg metadata.
295  // Each MDNode is a list in the form of "key", N number of values which is
296  // the same number of values as their are kernel arguments.
297
298  // MDNode for the kernel argument address space qualifiers.
299  SmallVector<llvm::Value*, 8> addressQuals;
300  addressQuals.push_back(llvm::MDString::get(Context, "kernel_arg_addr_space"));
301
302  // MDNode for the kernel argument access qualifiers (images only).
303  SmallVector<llvm::Value*, 8> accessQuals;
304  accessQuals.push_back(llvm::MDString::get(Context, "kernel_arg_access_qual"));
305
306  // MDNode for the kernel argument type names.
307  SmallVector<llvm::Value*, 8> argTypeNames;
308  argTypeNames.push_back(llvm::MDString::get(Context, "kernel_arg_type"));
309
310  // MDNode for the kernel argument type qualifiers.
311  SmallVector<llvm::Value*, 8> argTypeQuals;
312  argTypeQuals.push_back(llvm::MDString::get(Context, "kernel_arg_type_qual"));
313
314  // MDNode for the kernel argument names.
315  SmallVector<llvm::Value*, 8> argNames;
316  argNames.push_back(llvm::MDString::get(Context, "kernel_arg_name"));
317
318  for (unsigned i = 0, e = FD->getNumParams(); i != e; ++i) {
319    const ParmVarDecl *parm = FD->getParamDecl(i);
320    QualType ty = parm->getType();
321    std::string typeQuals;
322
323    if (ty->isPointerType()) {
324      QualType pointeeTy = ty->getPointeeType();
325
326      // Get address qualifier.
327      addressQuals.push_back(Builder.getInt32(ASTCtx.getTargetAddressSpace(
328        pointeeTy.getAddressSpace())));
329
330      // Get argument type name.
331      std::string typeName = pointeeTy.getUnqualifiedType().getAsString() + "*";
332
333      // Turn "unsigned type" to "utype"
334      std::string::size_type pos = typeName.find("unsigned");
335      if (pos != std::string::npos)
336        typeName.erase(pos+1, 8);
337
338      argTypeNames.push_back(llvm::MDString::get(Context, typeName));
339
340      // Get argument type qualifiers:
341      if (ty.isRestrictQualified())
342        typeQuals = "restrict";
343      if (pointeeTy.isConstQualified() ||
344          (pointeeTy.getAddressSpace() == LangAS::opencl_constant))
345        typeQuals += typeQuals.empty() ? "const" : " const";
346      if (pointeeTy.isVolatileQualified())
347        typeQuals += typeQuals.empty() ? "volatile" : " volatile";
348    } else {
349      addressQuals.push_back(Builder.getInt32(0));
350
351      // Get argument type name.
352      std::string typeName = ty.getUnqualifiedType().getAsString();
353
354      // Turn "unsigned type" to "utype"
355      std::string::size_type pos = typeName.find("unsigned");
356      if (pos != std::string::npos)
357        typeName.erase(pos+1, 8);
358
359      argTypeNames.push_back(llvm::MDString::get(Context, typeName));
360
361      // Get argument type qualifiers:
362      if (ty.isConstQualified())
363        typeQuals = "const";
364      if (ty.isVolatileQualified())
365        typeQuals += typeQuals.empty() ? "volatile" : " volatile";
366    }
367
368    argTypeQuals.push_back(llvm::MDString::get(Context, typeQuals));
369
370    // Get image access qualifier:
371    if (ty->isImageType()) {
372      if (parm->hasAttr<OpenCLImageAccessAttr>() &&
373          parm->getAttr<OpenCLImageAccessAttr>()->getAccess() == CLIA_write_only)
374        accessQuals.push_back(llvm::MDString::get(Context, "write_only"));
375      else
376        accessQuals.push_back(llvm::MDString::get(Context, "read_only"));
377    } else
378      accessQuals.push_back(llvm::MDString::get(Context, "none"));
379
380    // Get argument name.
381    argNames.push_back(llvm::MDString::get(Context, parm->getName()));
382  }
383
384  kernelMDArgs.push_back(llvm::MDNode::get(Context, addressQuals));
385  kernelMDArgs.push_back(llvm::MDNode::get(Context, accessQuals));
386  kernelMDArgs.push_back(llvm::MDNode::get(Context, argTypeNames));
387  kernelMDArgs.push_back(llvm::MDNode::get(Context, argTypeQuals));
388  kernelMDArgs.push_back(llvm::MDNode::get(Context, argNames));
389}
390
391void CodeGenFunction::EmitOpenCLKernelMetadata(const FunctionDecl *FD,
392                                               llvm::Function *Fn)
393{
394  if (!FD->hasAttr<OpenCLKernelAttr>())
395    return;
396
397  llvm::LLVMContext &Context = getLLVMContext();
398
399  SmallVector <llvm::Value*, 5> kernelMDArgs;
400  kernelMDArgs.push_back(Fn);
401
402  if (CGM.getCodeGenOpts().EmitOpenCLArgMetadata)
403    GenOpenCLArgMetadata(FD, Fn, CGM, Context, kernelMDArgs,
404                         Builder, getContext());
405
406  if (FD->hasAttr<VecTypeHintAttr>()) {
407    VecTypeHintAttr *attr = FD->getAttr<VecTypeHintAttr>();
408    QualType hintQTy = attr->getTypeHint();
409    const ExtVectorType *hintEltQTy = hintQTy->getAs<ExtVectorType>();
410    bool isSignedInteger =
411        hintQTy->isSignedIntegerType() ||
412        (hintEltQTy && hintEltQTy->getElementType()->isSignedIntegerType());
413    llvm::Value *attrMDArgs[] = {
414      llvm::MDString::get(Context, "vec_type_hint"),
415      llvm::UndefValue::get(CGM.getTypes().ConvertType(attr->getTypeHint())),
416      llvm::ConstantInt::get(
417          llvm::IntegerType::get(Context, 32),
418          llvm::APInt(32, (uint64_t)(isSignedInteger ? 1 : 0)))
419    };
420    kernelMDArgs.push_back(llvm::MDNode::get(Context, attrMDArgs));
421  }
422
423  if (FD->hasAttr<WorkGroupSizeHintAttr>()) {
424    WorkGroupSizeHintAttr *attr = FD->getAttr<WorkGroupSizeHintAttr>();
425    llvm::Value *attrMDArgs[] = {
426      llvm::MDString::get(Context, "work_group_size_hint"),
427      Builder.getInt32(attr->getXDim()),
428      Builder.getInt32(attr->getYDim()),
429      Builder.getInt32(attr->getZDim())
430    };
431    kernelMDArgs.push_back(llvm::MDNode::get(Context, attrMDArgs));
432  }
433
434  if (FD->hasAttr<ReqdWorkGroupSizeAttr>()) {
435    ReqdWorkGroupSizeAttr *attr = FD->getAttr<ReqdWorkGroupSizeAttr>();
436    llvm::Value *attrMDArgs[] = {
437      llvm::MDString::get(Context, "reqd_work_group_size"),
438      Builder.getInt32(attr->getXDim()),
439      Builder.getInt32(attr->getYDim()),
440      Builder.getInt32(attr->getZDim())
441    };
442    kernelMDArgs.push_back(llvm::MDNode::get(Context, attrMDArgs));
443  }
444
445  llvm::MDNode *kernelMDNode = llvm::MDNode::get(Context, kernelMDArgs);
446  llvm::NamedMDNode *OpenCLKernelMetadata =
447    CGM.getModule().getOrInsertNamedMetadata("opencl.kernels");
448  OpenCLKernelMetadata->addOperand(kernelMDNode);
449}
450
451void CodeGenFunction::StartFunction(GlobalDecl GD, QualType RetTy,
452                                    llvm::Function *Fn,
453                                    const CGFunctionInfo &FnInfo,
454                                    const FunctionArgList &Args,
455                                    SourceLocation StartLoc) {
456  const Decl *D = GD.getDecl();
457
458  DidCallStackSave = false;
459  CurCodeDecl = CurFuncDecl = D;
460  FnRetTy = RetTy;
461  CurFn = Fn;
462  CurFnInfo = &FnInfo;
463  assert(CurFn->isDeclaration() && "Function already has body?");
464
465  if (CGM.getSanitizerBlacklist().isIn(*Fn)) {
466    SanOpts = &SanitizerOptions::Disabled;
467    SanitizePerformTypeCheck = false;
468  }
469
470  // Pass inline keyword to optimizer if it appears explicitly on any
471  // declaration.
472  if (!CGM.getCodeGenOpts().NoInline)
473    if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D))
474      for (FunctionDecl::redecl_iterator RI = FD->redecls_begin(),
475             RE = FD->redecls_end(); RI != RE; ++RI)
476        if (RI->isInlineSpecified()) {
477          Fn->addFnAttr(llvm::Attribute::InlineHint);
478          break;
479        }
480
481  if (getLangOpts().OpenCL) {
482    // Add metadata for a kernel function.
483    if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D))
484      EmitOpenCLKernelMetadata(FD, Fn);
485  }
486
487  llvm::BasicBlock *EntryBB = createBasicBlock("entry", CurFn);
488
489  // Create a marker to make it easy to insert allocas into the entryblock
490  // later.  Don't create this with the builder, because we don't want it
491  // folded.
492  llvm::Value *Undef = llvm::UndefValue::get(Int32Ty);
493  AllocaInsertPt = new llvm::BitCastInst(Undef, Int32Ty, "", EntryBB);
494  if (Builder.isNamePreserving())
495    AllocaInsertPt->setName("allocapt");
496
497  ReturnBlock = getJumpDestInCurrentScope("return");
498
499  Builder.SetInsertPoint(EntryBB);
500
501  // Emit subprogram debug descriptor.
502  if (CGDebugInfo *DI = getDebugInfo()) {
503    SmallVector<QualType, 16> ArgTypes;
504    for (FunctionArgList::const_iterator i = Args.begin(), e = Args.end();
505	 i != e; ++i) {
506      ArgTypes.push_back((*i)->getType());
507    }
508
509    QualType FnType =
510      getContext().getFunctionType(RetTy, ArgTypes,
511                                   FunctionProtoType::ExtProtoInfo());
512
513    DI->setLocation(StartLoc);
514    DI->EmitFunctionStart(GD, FnType, CurFn, Builder);
515  }
516
517  if (ShouldInstrumentFunction())
518    EmitFunctionInstrumentation("__cyg_profile_func_enter");
519
520  if (CGM.getCodeGenOpts().InstrumentForProfiling)
521    EmitMCountInstrumentation();
522
523  if (RetTy->isVoidType()) {
524    // Void type; nothing to return.
525    ReturnValue = 0;
526  } else if (CurFnInfo->getReturnInfo().getKind() == ABIArgInfo::Indirect &&
527             !hasScalarEvaluationKind(CurFnInfo->getReturnType())) {
528    // Indirect aggregate return; emit returned value directly into sret slot.
529    // This reduces code size, and affects correctness in C++.
530    ReturnValue = CurFn->arg_begin();
531  } else {
532    ReturnValue = CreateIRTemp(RetTy, "retval");
533
534    // Tell the epilog emitter to autorelease the result.  We do this
535    // now so that various specialized functions can suppress it
536    // during their IR-generation.
537    if (getLangOpts().ObjCAutoRefCount &&
538        !CurFnInfo->isReturnsRetained() &&
539        RetTy->isObjCRetainableType())
540      AutoreleaseResult = true;
541  }
542
543  EmitStartEHSpec(CurCodeDecl);
544
545  PrologueCleanupDepth = EHStack.stable_begin();
546  EmitFunctionProlog(*CurFnInfo, CurFn, Args);
547
548  if (D && isa<CXXMethodDecl>(D) && cast<CXXMethodDecl>(D)->isInstance()) {
549    CGM.getCXXABI().EmitInstanceFunctionProlog(*this);
550    const CXXMethodDecl *MD = cast<CXXMethodDecl>(D);
551    if (MD->getParent()->isLambda() &&
552        MD->getOverloadedOperator() == OO_Call) {
553      // We're in a lambda; figure out the captures.
554      MD->getParent()->getCaptureFields(LambdaCaptureFields,
555                                        LambdaThisCaptureField);
556      if (LambdaThisCaptureField) {
557        // If this lambda captures this, load it.
558        QualType LambdaTagType =
559            getContext().getTagDeclType(LambdaThisCaptureField->getParent());
560        LValue LambdaLV = MakeNaturalAlignAddrLValue(CXXABIThisValue,
561                                                     LambdaTagType);
562        LValue ThisLValue = EmitLValueForField(LambdaLV,
563                                               LambdaThisCaptureField);
564        CXXThisValue = EmitLoadOfLValue(ThisLValue).getScalarVal();
565      }
566    } else {
567      // Not in a lambda; just use 'this' from the method.
568      // FIXME: Should we generate a new load for each use of 'this'?  The
569      // fast register allocator would be happier...
570      CXXThisValue = CXXABIThisValue;
571    }
572  }
573
574  // If any of the arguments have a variably modified type, make sure to
575  // emit the type size.
576  for (FunctionArgList::const_iterator i = Args.begin(), e = Args.end();
577       i != e; ++i) {
578    const VarDecl *VD = *i;
579
580    // Dig out the type as written from ParmVarDecls; it's unclear whether
581    // the standard (C99 6.9.1p10) requires this, but we're following the
582    // precedent set by gcc.
583    QualType Ty;
584    if (const ParmVarDecl *PVD = dyn_cast<ParmVarDecl>(VD))
585      Ty = PVD->getOriginalType();
586    else
587      Ty = VD->getType();
588
589    if (Ty->isVariablyModifiedType())
590      EmitVariablyModifiedType(Ty);
591  }
592  // Emit a location at the end of the prologue.
593  if (CGDebugInfo *DI = getDebugInfo())
594    DI->EmitLocation(Builder, StartLoc);
595}
596
597void CodeGenFunction::EmitFunctionBody(FunctionArgList &Args) {
598  const FunctionDecl *FD = cast<FunctionDecl>(CurGD.getDecl());
599  assert(FD->getBody());
600  if (const CompoundStmt *S = dyn_cast<CompoundStmt>(FD->getBody()))
601    EmitCompoundStmtWithoutScope(*S);
602  else
603    EmitStmt(FD->getBody());
604}
605
606/// Tries to mark the given function nounwind based on the
607/// non-existence of any throwing calls within it.  We believe this is
608/// lightweight enough to do at -O0.
609static void TryMarkNoThrow(llvm::Function *F) {
610  // LLVM treats 'nounwind' on a function as part of the type, so we
611  // can't do this on functions that can be overwritten.
612  if (F->mayBeOverridden()) return;
613
614  for (llvm::Function::iterator FI = F->begin(), FE = F->end(); FI != FE; ++FI)
615    for (llvm::BasicBlock::iterator
616           BI = FI->begin(), BE = FI->end(); BI != BE; ++BI)
617      if (llvm::CallInst *Call = dyn_cast<llvm::CallInst>(&*BI)) {
618        if (!Call->doesNotThrow())
619          return;
620      } else if (isa<llvm::ResumeInst>(&*BI)) {
621        return;
622      }
623  F->setDoesNotThrow();
624}
625
626void CodeGenFunction::GenerateCode(GlobalDecl GD, llvm::Function *Fn,
627                                   const CGFunctionInfo &FnInfo) {
628  const FunctionDecl *FD = cast<FunctionDecl>(GD.getDecl());
629
630  // Check if we should generate debug info for this function.
631  if (!FD->hasAttr<NoDebugAttr>())
632    maybeInitializeDebugInfo();
633
634  FunctionArgList Args;
635  QualType ResTy = FD->getResultType();
636
637  CurGD = GD;
638  if (isa<CXXMethodDecl>(FD) && cast<CXXMethodDecl>(FD)->isInstance())
639    CGM.getCXXABI().BuildInstanceFunctionParams(*this, ResTy, Args);
640
641  for (unsigned i = 0, e = FD->getNumParams(); i != e; ++i)
642    Args.push_back(FD->getParamDecl(i));
643
644  SourceRange BodyRange;
645  if (Stmt *Body = FD->getBody()) BodyRange = Body->getSourceRange();
646
647  // CalleeWithThisReturn keeps track of the last callee inside this function
648  // that returns 'this'. Before starting the function, we set it to null.
649  CalleeWithThisReturn = 0;
650
651  // Emit the standard function prologue.
652  StartFunction(GD, ResTy, Fn, FnInfo, Args, BodyRange.getBegin());
653
654  // Generate the body of the function.
655  if (isa<CXXDestructorDecl>(FD))
656    EmitDestructorBody(Args);
657  else if (isa<CXXConstructorDecl>(FD))
658    EmitConstructorBody(Args);
659  else if (getLangOpts().CUDA &&
660           !CGM.getCodeGenOpts().CUDAIsDevice &&
661           FD->hasAttr<CUDAGlobalAttr>())
662    CGM.getCUDARuntime().EmitDeviceStubBody(*this, Args);
663  else if (isa<CXXConversionDecl>(FD) &&
664           cast<CXXConversionDecl>(FD)->isLambdaToBlockPointerConversion()) {
665    // The lambda conversion to block pointer is special; the semantics can't be
666    // expressed in the AST, so IRGen needs to special-case it.
667    EmitLambdaToBlockPointerBody(Args);
668  } else if (isa<CXXMethodDecl>(FD) &&
669             cast<CXXMethodDecl>(FD)->isLambdaStaticInvoker()) {
670    // The lambda "__invoke" function is special, because it forwards or
671    // clones the body of the function call operator (but is actually static).
672    EmitLambdaStaticInvokeFunction(cast<CXXMethodDecl>(FD));
673  } else if (FD->isDefaulted() && isa<CXXMethodDecl>(FD) &&
674             cast<CXXMethodDecl>(FD)->isCopyAssignmentOperator()) {
675    // Implicit copy-assignment gets the same special treatment as implicit
676    // copy-constructors.
677    emitImplicitAssignmentOperatorBody(Args);
678  }
679  else
680    EmitFunctionBody(Args);
681
682  // C++11 [stmt.return]p2:
683  //   Flowing off the end of a function [...] results in undefined behavior in
684  //   a value-returning function.
685  // C11 6.9.1p12:
686  //   If the '}' that terminates a function is reached, and the value of the
687  //   function call is used by the caller, the behavior is undefined.
688  if (getLangOpts().CPlusPlus && !FD->hasImplicitReturnZero() &&
689      !FD->getResultType()->isVoidType() && Builder.GetInsertBlock()) {
690    if (SanOpts->Return)
691      EmitCheck(Builder.getFalse(), "missing_return",
692                EmitCheckSourceLocation(FD->getLocation()),
693                ArrayRef<llvm::Value *>(), CRK_Unrecoverable);
694    else if (CGM.getCodeGenOpts().OptimizationLevel == 0)
695      Builder.CreateCall(CGM.getIntrinsic(llvm::Intrinsic::trap));
696    Builder.CreateUnreachable();
697    Builder.ClearInsertionPoint();
698  }
699
700  // Emit the standard function epilogue.
701  FinishFunction(BodyRange.getEnd());
702  // CalleeWithThisReturn keeps track of the last callee inside this function
703  // that returns 'this'. After finishing the function, we set it to null.
704  CalleeWithThisReturn = 0;
705
706  // If we haven't marked the function nothrow through other means, do
707  // a quick pass now to see if we can.
708  if (!CurFn->doesNotThrow())
709    TryMarkNoThrow(CurFn);
710}
711
712/// ContainsLabel - Return true if the statement contains a label in it.  If
713/// this statement is not executed normally, it not containing a label means
714/// that we can just remove the code.
715bool CodeGenFunction::ContainsLabel(const Stmt *S, bool IgnoreCaseStmts) {
716  // Null statement, not a label!
717  if (S == 0) return false;
718
719  // If this is a label, we have to emit the code, consider something like:
720  // if (0) {  ...  foo:  bar(); }  goto foo;
721  //
722  // TODO: If anyone cared, we could track __label__'s, since we know that you
723  // can't jump to one from outside their declared region.
724  if (isa<LabelStmt>(S))
725    return true;
726
727  // If this is a case/default statement, and we haven't seen a switch, we have
728  // to emit the code.
729  if (isa<SwitchCase>(S) && !IgnoreCaseStmts)
730    return true;
731
732  // If this is a switch statement, we want to ignore cases below it.
733  if (isa<SwitchStmt>(S))
734    IgnoreCaseStmts = true;
735
736  // Scan subexpressions for verboten labels.
737  for (Stmt::const_child_range I = S->children(); I; ++I)
738    if (ContainsLabel(*I, IgnoreCaseStmts))
739      return true;
740
741  return false;
742}
743
744/// containsBreak - Return true if the statement contains a break out of it.
745/// If the statement (recursively) contains a switch or loop with a break
746/// inside of it, this is fine.
747bool CodeGenFunction::containsBreak(const Stmt *S) {
748  // Null statement, not a label!
749  if (S == 0) return false;
750
751  // If this is a switch or loop that defines its own break scope, then we can
752  // include it and anything inside of it.
753  if (isa<SwitchStmt>(S) || isa<WhileStmt>(S) || isa<DoStmt>(S) ||
754      isa<ForStmt>(S))
755    return false;
756
757  if (isa<BreakStmt>(S))
758    return true;
759
760  // Scan subexpressions for verboten breaks.
761  for (Stmt::const_child_range I = S->children(); I; ++I)
762    if (containsBreak(*I))
763      return true;
764
765  return false;
766}
767
768
769/// ConstantFoldsToSimpleInteger - If the specified expression does not fold
770/// to a constant, or if it does but contains a label, return false.  If it
771/// constant folds return true and set the boolean result in Result.
772bool CodeGenFunction::ConstantFoldsToSimpleInteger(const Expr *Cond,
773                                                   bool &ResultBool) {
774  llvm::APSInt ResultInt;
775  if (!ConstantFoldsToSimpleInteger(Cond, ResultInt))
776    return false;
777
778  ResultBool = ResultInt.getBoolValue();
779  return true;
780}
781
782/// ConstantFoldsToSimpleInteger - If the specified expression does not fold
783/// to a constant, or if it does but contains a label, return false.  If it
784/// constant folds return true and set the folded value.
785bool CodeGenFunction::
786ConstantFoldsToSimpleInteger(const Expr *Cond, llvm::APSInt &ResultInt) {
787  // FIXME: Rename and handle conversion of other evaluatable things
788  // to bool.
789  llvm::APSInt Int;
790  if (!Cond->EvaluateAsInt(Int, getContext()))
791    return false;  // Not foldable, not integer or not fully evaluatable.
792
793  if (CodeGenFunction::ContainsLabel(Cond))
794    return false;  // Contains a label.
795
796  ResultInt = Int;
797  return true;
798}
799
800
801
802/// EmitBranchOnBoolExpr - Emit a branch on a boolean condition (e.g. for an if
803/// statement) to the specified blocks.  Based on the condition, this might try
804/// to simplify the codegen of the conditional based on the branch.
805///
806void CodeGenFunction::EmitBranchOnBoolExpr(const Expr *Cond,
807                                           llvm::BasicBlock *TrueBlock,
808                                           llvm::BasicBlock *FalseBlock) {
809  Cond = Cond->IgnoreParens();
810
811  if (const BinaryOperator *CondBOp = dyn_cast<BinaryOperator>(Cond)) {
812    // Handle X && Y in a condition.
813    if (CondBOp->getOpcode() == BO_LAnd) {
814      // If we have "1 && X", simplify the code.  "0 && X" would have constant
815      // folded if the case was simple enough.
816      bool ConstantBool = false;
817      if (ConstantFoldsToSimpleInteger(CondBOp->getLHS(), ConstantBool) &&
818          ConstantBool) {
819        // br(1 && X) -> br(X).
820        return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock);
821      }
822
823      // If we have "X && 1", simplify the code to use an uncond branch.
824      // "X && 0" would have been constant folded to 0.
825      if (ConstantFoldsToSimpleInteger(CondBOp->getRHS(), ConstantBool) &&
826          ConstantBool) {
827        // br(X && 1) -> br(X).
828        return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock);
829      }
830
831      // Emit the LHS as a conditional.  If the LHS conditional is false, we
832      // want to jump to the FalseBlock.
833      llvm::BasicBlock *LHSTrue = createBasicBlock("land.lhs.true");
834
835      ConditionalEvaluation eval(*this);
836      EmitBranchOnBoolExpr(CondBOp->getLHS(), LHSTrue, FalseBlock);
837      EmitBlock(LHSTrue);
838
839      // Any temporaries created here are conditional.
840      eval.begin(*this);
841      EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock);
842      eval.end(*this);
843
844      return;
845    }
846
847    if (CondBOp->getOpcode() == BO_LOr) {
848      // If we have "0 || X", simplify the code.  "1 || X" would have constant
849      // folded if the case was simple enough.
850      bool ConstantBool = false;
851      if (ConstantFoldsToSimpleInteger(CondBOp->getLHS(), ConstantBool) &&
852          !ConstantBool) {
853        // br(0 || X) -> br(X).
854        return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock);
855      }
856
857      // If we have "X || 0", simplify the code to use an uncond branch.
858      // "X || 1" would have been constant folded to 1.
859      if (ConstantFoldsToSimpleInteger(CondBOp->getRHS(), ConstantBool) &&
860          !ConstantBool) {
861        // br(X || 0) -> br(X).
862        return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock);
863      }
864
865      // Emit the LHS as a conditional.  If the LHS conditional is true, we
866      // want to jump to the TrueBlock.
867      llvm::BasicBlock *LHSFalse = createBasicBlock("lor.lhs.false");
868
869      ConditionalEvaluation eval(*this);
870      EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, LHSFalse);
871      EmitBlock(LHSFalse);
872
873      // Any temporaries created here are conditional.
874      eval.begin(*this);
875      EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock);
876      eval.end(*this);
877
878      return;
879    }
880  }
881
882  if (const UnaryOperator *CondUOp = dyn_cast<UnaryOperator>(Cond)) {
883    // br(!x, t, f) -> br(x, f, t)
884    if (CondUOp->getOpcode() == UO_LNot)
885      return EmitBranchOnBoolExpr(CondUOp->getSubExpr(), FalseBlock, TrueBlock);
886  }
887
888  if (const ConditionalOperator *CondOp = dyn_cast<ConditionalOperator>(Cond)) {
889    // br(c ? x : y, t, f) -> br(c, br(x, t, f), br(y, t, f))
890    llvm::BasicBlock *LHSBlock = createBasicBlock("cond.true");
891    llvm::BasicBlock *RHSBlock = createBasicBlock("cond.false");
892
893    ConditionalEvaluation cond(*this);
894    EmitBranchOnBoolExpr(CondOp->getCond(), LHSBlock, RHSBlock);
895
896    cond.begin(*this);
897    EmitBlock(LHSBlock);
898    EmitBranchOnBoolExpr(CondOp->getLHS(), TrueBlock, FalseBlock);
899    cond.end(*this);
900
901    cond.begin(*this);
902    EmitBlock(RHSBlock);
903    EmitBranchOnBoolExpr(CondOp->getRHS(), TrueBlock, FalseBlock);
904    cond.end(*this);
905
906    return;
907  }
908
909  // Emit the code with the fully general case.
910  llvm::Value *CondV = EvaluateExprAsBool(Cond);
911  Builder.CreateCondBr(CondV, TrueBlock, FalseBlock);
912}
913
914/// ErrorUnsupported - Print out an error that codegen doesn't support the
915/// specified stmt yet.
916void CodeGenFunction::ErrorUnsupported(const Stmt *S, const char *Type,
917                                       bool OmitOnError) {
918  CGM.ErrorUnsupported(S, Type, OmitOnError);
919}
920
921/// emitNonZeroVLAInit - Emit the "zero" initialization of a
922/// variable-length array whose elements have a non-zero bit-pattern.
923///
924/// \param baseType the inner-most element type of the array
925/// \param src - a char* pointing to the bit-pattern for a single
926/// base element of the array
927/// \param sizeInChars - the total size of the VLA, in chars
928static void emitNonZeroVLAInit(CodeGenFunction &CGF, QualType baseType,
929                               llvm::Value *dest, llvm::Value *src,
930                               llvm::Value *sizeInChars) {
931  std::pair<CharUnits,CharUnits> baseSizeAndAlign
932    = CGF.getContext().getTypeInfoInChars(baseType);
933
934  CGBuilderTy &Builder = CGF.Builder;
935
936  llvm::Value *baseSizeInChars
937    = llvm::ConstantInt::get(CGF.IntPtrTy, baseSizeAndAlign.first.getQuantity());
938
939  llvm::Type *i8p = Builder.getInt8PtrTy();
940
941  llvm::Value *begin = Builder.CreateBitCast(dest, i8p, "vla.begin");
942  llvm::Value *end = Builder.CreateInBoundsGEP(dest, sizeInChars, "vla.end");
943
944  llvm::BasicBlock *originBB = CGF.Builder.GetInsertBlock();
945  llvm::BasicBlock *loopBB = CGF.createBasicBlock("vla-init.loop");
946  llvm::BasicBlock *contBB = CGF.createBasicBlock("vla-init.cont");
947
948  // Make a loop over the VLA.  C99 guarantees that the VLA element
949  // count must be nonzero.
950  CGF.EmitBlock(loopBB);
951
952  llvm::PHINode *cur = Builder.CreatePHI(i8p, 2, "vla.cur");
953  cur->addIncoming(begin, originBB);
954
955  // memcpy the individual element bit-pattern.
956  Builder.CreateMemCpy(cur, src, baseSizeInChars,
957                       baseSizeAndAlign.second.getQuantity(),
958                       /*volatile*/ false);
959
960  // Go to the next element.
961  llvm::Value *next = Builder.CreateConstInBoundsGEP1_32(cur, 1, "vla.next");
962
963  // Leave if that's the end of the VLA.
964  llvm::Value *done = Builder.CreateICmpEQ(next, end, "vla-init.isdone");
965  Builder.CreateCondBr(done, contBB, loopBB);
966  cur->addIncoming(next, loopBB);
967
968  CGF.EmitBlock(contBB);
969}
970
971void
972CodeGenFunction::EmitNullInitialization(llvm::Value *DestPtr, QualType Ty) {
973  // Ignore empty classes in C++.
974  if (getLangOpts().CPlusPlus) {
975    if (const RecordType *RT = Ty->getAs<RecordType>()) {
976      if (cast<CXXRecordDecl>(RT->getDecl())->isEmpty())
977        return;
978    }
979  }
980
981  // Cast the dest ptr to the appropriate i8 pointer type.
982  unsigned DestAS =
983    cast<llvm::PointerType>(DestPtr->getType())->getAddressSpace();
984  llvm::Type *BP = Builder.getInt8PtrTy(DestAS);
985  if (DestPtr->getType() != BP)
986    DestPtr = Builder.CreateBitCast(DestPtr, BP);
987
988  // Get size and alignment info for this aggregate.
989  std::pair<CharUnits, CharUnits> TypeInfo =
990    getContext().getTypeInfoInChars(Ty);
991  CharUnits Size = TypeInfo.first;
992  CharUnits Align = TypeInfo.second;
993
994  llvm::Value *SizeVal;
995  const VariableArrayType *vla;
996
997  // Don't bother emitting a zero-byte memset.
998  if (Size.isZero()) {
999    // But note that getTypeInfo returns 0 for a VLA.
1000    if (const VariableArrayType *vlaType =
1001          dyn_cast_or_null<VariableArrayType>(
1002                                          getContext().getAsArrayType(Ty))) {
1003      QualType eltType;
1004      llvm::Value *numElts;
1005      llvm::tie(numElts, eltType) = getVLASize(vlaType);
1006
1007      SizeVal = numElts;
1008      CharUnits eltSize = getContext().getTypeSizeInChars(eltType);
1009      if (!eltSize.isOne())
1010        SizeVal = Builder.CreateNUWMul(SizeVal, CGM.getSize(eltSize));
1011      vla = vlaType;
1012    } else {
1013      return;
1014    }
1015  } else {
1016    SizeVal = CGM.getSize(Size);
1017    vla = 0;
1018  }
1019
1020  // If the type contains a pointer to data member we can't memset it to zero.
1021  // Instead, create a null constant and copy it to the destination.
1022  // TODO: there are other patterns besides zero that we can usefully memset,
1023  // like -1, which happens to be the pattern used by member-pointers.
1024  if (!CGM.getTypes().isZeroInitializable(Ty)) {
1025    // For a VLA, emit a single element, then splat that over the VLA.
1026    if (vla) Ty = getContext().getBaseElementType(vla);
1027
1028    llvm::Constant *NullConstant = CGM.EmitNullConstant(Ty);
1029
1030    llvm::GlobalVariable *NullVariable =
1031      new llvm::GlobalVariable(CGM.getModule(), NullConstant->getType(),
1032                               /*isConstant=*/true,
1033                               llvm::GlobalVariable::PrivateLinkage,
1034                               NullConstant, Twine());
1035    llvm::Value *SrcPtr =
1036      Builder.CreateBitCast(NullVariable, Builder.getInt8PtrTy());
1037
1038    if (vla) return emitNonZeroVLAInit(*this, Ty, DestPtr, SrcPtr, SizeVal);
1039
1040    // Get and call the appropriate llvm.memcpy overload.
1041    Builder.CreateMemCpy(DestPtr, SrcPtr, SizeVal, Align.getQuantity(), false);
1042    return;
1043  }
1044
1045  // Otherwise, just memset the whole thing to zero.  This is legal
1046  // because in LLVM, all default initializers (other than the ones we just
1047  // handled above) are guaranteed to have a bit pattern of all zeros.
1048  Builder.CreateMemSet(DestPtr, Builder.getInt8(0), SizeVal,
1049                       Align.getQuantity(), false);
1050}
1051
1052llvm::BlockAddress *CodeGenFunction::GetAddrOfLabel(const LabelDecl *L) {
1053  // Make sure that there is a block for the indirect goto.
1054  if (IndirectBranch == 0)
1055    GetIndirectGotoBlock();
1056
1057  llvm::BasicBlock *BB = getJumpDestForLabel(L).getBlock();
1058
1059  // Make sure the indirect branch includes all of the address-taken blocks.
1060  IndirectBranch->addDestination(BB);
1061  return llvm::BlockAddress::get(CurFn, BB);
1062}
1063
1064llvm::BasicBlock *CodeGenFunction::GetIndirectGotoBlock() {
1065  // If we already made the indirect branch for indirect goto, return its block.
1066  if (IndirectBranch) return IndirectBranch->getParent();
1067
1068  CGBuilderTy TmpBuilder(createBasicBlock("indirectgoto"));
1069
1070  // Create the PHI node that indirect gotos will add entries to.
1071  llvm::Value *DestVal = TmpBuilder.CreatePHI(Int8PtrTy, 0,
1072                                              "indirect.goto.dest");
1073
1074  // Create the indirect branch instruction.
1075  IndirectBranch = TmpBuilder.CreateIndirectBr(DestVal);
1076  return IndirectBranch->getParent();
1077}
1078
1079/// Computes the length of an array in elements, as well as the base
1080/// element type and a properly-typed first element pointer.
1081llvm::Value *CodeGenFunction::emitArrayLength(const ArrayType *origArrayType,
1082                                              QualType &baseType,
1083                                              llvm::Value *&addr) {
1084  const ArrayType *arrayType = origArrayType;
1085
1086  // If it's a VLA, we have to load the stored size.  Note that
1087  // this is the size of the VLA in bytes, not its size in elements.
1088  llvm::Value *numVLAElements = 0;
1089  if (isa<VariableArrayType>(arrayType)) {
1090    numVLAElements = getVLASize(cast<VariableArrayType>(arrayType)).first;
1091
1092    // Walk into all VLAs.  This doesn't require changes to addr,
1093    // which has type T* where T is the first non-VLA element type.
1094    do {
1095      QualType elementType = arrayType->getElementType();
1096      arrayType = getContext().getAsArrayType(elementType);
1097
1098      // If we only have VLA components, 'addr' requires no adjustment.
1099      if (!arrayType) {
1100        baseType = elementType;
1101        return numVLAElements;
1102      }
1103    } while (isa<VariableArrayType>(arrayType));
1104
1105    // We get out here only if we find a constant array type
1106    // inside the VLA.
1107  }
1108
1109  // We have some number of constant-length arrays, so addr should
1110  // have LLVM type [M x [N x [...]]]*.  Build a GEP that walks
1111  // down to the first element of addr.
1112  SmallVector<llvm::Value*, 8> gepIndices;
1113
1114  // GEP down to the array type.
1115  llvm::ConstantInt *zero = Builder.getInt32(0);
1116  gepIndices.push_back(zero);
1117
1118  uint64_t countFromCLAs = 1;
1119  QualType eltType;
1120
1121  llvm::ArrayType *llvmArrayType =
1122    dyn_cast<llvm::ArrayType>(
1123      cast<llvm::PointerType>(addr->getType())->getElementType());
1124  while (llvmArrayType) {
1125    assert(isa<ConstantArrayType>(arrayType));
1126    assert(cast<ConstantArrayType>(arrayType)->getSize().getZExtValue()
1127             == llvmArrayType->getNumElements());
1128
1129    gepIndices.push_back(zero);
1130    countFromCLAs *= llvmArrayType->getNumElements();
1131    eltType = arrayType->getElementType();
1132
1133    llvmArrayType =
1134      dyn_cast<llvm::ArrayType>(llvmArrayType->getElementType());
1135    arrayType = getContext().getAsArrayType(arrayType->getElementType());
1136    assert((!llvmArrayType || arrayType) &&
1137           "LLVM and Clang types are out-of-synch");
1138  }
1139
1140  if (arrayType) {
1141    // From this point onwards, the Clang array type has been emitted
1142    // as some other type (probably a packed struct). Compute the array
1143    // size, and just emit the 'begin' expression as a bitcast.
1144    while (arrayType) {
1145      countFromCLAs *=
1146          cast<ConstantArrayType>(arrayType)->getSize().getZExtValue();
1147      eltType = arrayType->getElementType();
1148      arrayType = getContext().getAsArrayType(eltType);
1149    }
1150
1151    unsigned AddressSpace = addr->getType()->getPointerAddressSpace();
1152    llvm::Type *BaseType = ConvertType(eltType)->getPointerTo(AddressSpace);
1153    addr = Builder.CreateBitCast(addr, BaseType, "array.begin");
1154  } else {
1155    // Create the actual GEP.
1156    addr = Builder.CreateInBoundsGEP(addr, gepIndices, "array.begin");
1157  }
1158
1159  baseType = eltType;
1160
1161  llvm::Value *numElements
1162    = llvm::ConstantInt::get(SizeTy, countFromCLAs);
1163
1164  // If we had any VLA dimensions, factor them in.
1165  if (numVLAElements)
1166    numElements = Builder.CreateNUWMul(numVLAElements, numElements);
1167
1168  return numElements;
1169}
1170
1171std::pair<llvm::Value*, QualType>
1172CodeGenFunction::getVLASize(QualType type) {
1173  const VariableArrayType *vla = getContext().getAsVariableArrayType(type);
1174  assert(vla && "type was not a variable array type!");
1175  return getVLASize(vla);
1176}
1177
1178std::pair<llvm::Value*, QualType>
1179CodeGenFunction::getVLASize(const VariableArrayType *type) {
1180  // The number of elements so far; always size_t.
1181  llvm::Value *numElements = 0;
1182
1183  QualType elementType;
1184  do {
1185    elementType = type->getElementType();
1186    llvm::Value *vlaSize = VLASizeMap[type->getSizeExpr()];
1187    assert(vlaSize && "no size for VLA!");
1188    assert(vlaSize->getType() == SizeTy);
1189
1190    if (!numElements) {
1191      numElements = vlaSize;
1192    } else {
1193      // It's undefined behavior if this wraps around, so mark it that way.
1194      // FIXME: Teach -fcatch-undefined-behavior to trap this.
1195      numElements = Builder.CreateNUWMul(numElements, vlaSize);
1196    }
1197  } while ((type = getContext().getAsVariableArrayType(elementType)));
1198
1199  return std::pair<llvm::Value*,QualType>(numElements, elementType);
1200}
1201
1202void CodeGenFunction::EmitVariablyModifiedType(QualType type) {
1203  assert(type->isVariablyModifiedType() &&
1204         "Must pass variably modified type to EmitVLASizes!");
1205
1206  EnsureInsertPoint();
1207
1208  // We're going to walk down into the type and look for VLA
1209  // expressions.
1210  do {
1211    assert(type->isVariablyModifiedType());
1212
1213    const Type *ty = type.getTypePtr();
1214    switch (ty->getTypeClass()) {
1215
1216#define TYPE(Class, Base)
1217#define ABSTRACT_TYPE(Class, Base)
1218#define NON_CANONICAL_TYPE(Class, Base)
1219#define DEPENDENT_TYPE(Class, Base) case Type::Class:
1220#define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(Class, Base)
1221#include "clang/AST/TypeNodes.def"
1222      llvm_unreachable("unexpected dependent type!");
1223
1224    // These types are never variably-modified.
1225    case Type::Builtin:
1226    case Type::Complex:
1227    case Type::Vector:
1228    case Type::ExtVector:
1229    case Type::Record:
1230    case Type::Enum:
1231    case Type::Elaborated:
1232    case Type::TemplateSpecialization:
1233    case Type::ObjCObject:
1234    case Type::ObjCInterface:
1235    case Type::ObjCObjectPointer:
1236      llvm_unreachable("type class is never variably-modified!");
1237
1238    case Type::Pointer:
1239      type = cast<PointerType>(ty)->getPointeeType();
1240      break;
1241
1242    case Type::BlockPointer:
1243      type = cast<BlockPointerType>(ty)->getPointeeType();
1244      break;
1245
1246    case Type::LValueReference:
1247    case Type::RValueReference:
1248      type = cast<ReferenceType>(ty)->getPointeeType();
1249      break;
1250
1251    case Type::MemberPointer:
1252      type = cast<MemberPointerType>(ty)->getPointeeType();
1253      break;
1254
1255    case Type::ConstantArray:
1256    case Type::IncompleteArray:
1257      // Losing element qualification here is fine.
1258      type = cast<ArrayType>(ty)->getElementType();
1259      break;
1260
1261    case Type::VariableArray: {
1262      // Losing element qualification here is fine.
1263      const VariableArrayType *vat = cast<VariableArrayType>(ty);
1264
1265      // Unknown size indication requires no size computation.
1266      // Otherwise, evaluate and record it.
1267      if (const Expr *size = vat->getSizeExpr()) {
1268        // It's possible that we might have emitted this already,
1269        // e.g. with a typedef and a pointer to it.
1270        llvm::Value *&entry = VLASizeMap[size];
1271        if (!entry) {
1272          llvm::Value *Size = EmitScalarExpr(size);
1273
1274          // C11 6.7.6.2p5:
1275          //   If the size is an expression that is not an integer constant
1276          //   expression [...] each time it is evaluated it shall have a value
1277          //   greater than zero.
1278          if (SanOpts->VLABound &&
1279              size->getType()->isSignedIntegerType()) {
1280            llvm::Value *Zero = llvm::Constant::getNullValue(Size->getType());
1281            llvm::Constant *StaticArgs[] = {
1282              EmitCheckSourceLocation(size->getLocStart()),
1283              EmitCheckTypeDescriptor(size->getType())
1284            };
1285            EmitCheck(Builder.CreateICmpSGT(Size, Zero),
1286                      "vla_bound_not_positive", StaticArgs, Size,
1287                      CRK_Recoverable);
1288          }
1289
1290          // Always zexting here would be wrong if it weren't
1291          // undefined behavior to have a negative bound.
1292          entry = Builder.CreateIntCast(Size, SizeTy, /*signed*/ false);
1293        }
1294      }
1295      type = vat->getElementType();
1296      break;
1297    }
1298
1299    case Type::FunctionProto:
1300    case Type::FunctionNoProto:
1301      type = cast<FunctionType>(ty)->getResultType();
1302      break;
1303
1304    case Type::Paren:
1305    case Type::TypeOf:
1306    case Type::UnaryTransform:
1307    case Type::Attributed:
1308    case Type::SubstTemplateTypeParm:
1309      // Keep walking after single level desugaring.
1310      type = type.getSingleStepDesugaredType(getContext());
1311      break;
1312
1313    case Type::Typedef:
1314    case Type::Decltype:
1315    case Type::Auto:
1316      // Stop walking: nothing to do.
1317      return;
1318
1319    case Type::TypeOfExpr:
1320      // Stop walking: emit typeof expression.
1321      EmitIgnoredExpr(cast<TypeOfExprType>(ty)->getUnderlyingExpr());
1322      return;
1323
1324    case Type::Atomic:
1325      type = cast<AtomicType>(ty)->getValueType();
1326      break;
1327    }
1328  } while (type->isVariablyModifiedType());
1329}
1330
1331llvm::Value* CodeGenFunction::EmitVAListRef(const Expr* E) {
1332  if (getContext().getBuiltinVaListType()->isArrayType())
1333    return EmitScalarExpr(E);
1334  return EmitLValue(E).getAddress();
1335}
1336
1337void CodeGenFunction::EmitDeclRefExprDbgValue(const DeclRefExpr *E,
1338                                              llvm::Constant *Init) {
1339  assert (Init && "Invalid DeclRefExpr initializer!");
1340  if (CGDebugInfo *Dbg = getDebugInfo())
1341    if (CGM.getCodeGenOpts().getDebugInfo() >= CodeGenOptions::LimitedDebugInfo)
1342      Dbg->EmitGlobalVariable(E->getDecl(), Init);
1343}
1344
1345CodeGenFunction::PeepholeProtection
1346CodeGenFunction::protectFromPeepholes(RValue rvalue) {
1347  // At the moment, the only aggressive peephole we do in IR gen
1348  // is trunc(zext) folding, but if we add more, we can easily
1349  // extend this protection.
1350
1351  if (!rvalue.isScalar()) return PeepholeProtection();
1352  llvm::Value *value = rvalue.getScalarVal();
1353  if (!isa<llvm::ZExtInst>(value)) return PeepholeProtection();
1354
1355  // Just make an extra bitcast.
1356  assert(HaveInsertPoint());
1357  llvm::Instruction *inst = new llvm::BitCastInst(value, value->getType(), "",
1358                                                  Builder.GetInsertBlock());
1359
1360  PeepholeProtection protection;
1361  protection.Inst = inst;
1362  return protection;
1363}
1364
1365void CodeGenFunction::unprotectFromPeepholes(PeepholeProtection protection) {
1366  if (!protection.Inst) return;
1367
1368  // In theory, we could try to duplicate the peepholes now, but whatever.
1369  protection.Inst->eraseFromParent();
1370}
1371
1372llvm::Value *CodeGenFunction::EmitAnnotationCall(llvm::Value *AnnotationFn,
1373                                                 llvm::Value *AnnotatedVal,
1374                                                 StringRef AnnotationStr,
1375                                                 SourceLocation Location) {
1376  llvm::Value *Args[4] = {
1377    AnnotatedVal,
1378    Builder.CreateBitCast(CGM.EmitAnnotationString(AnnotationStr), Int8PtrTy),
1379    Builder.CreateBitCast(CGM.EmitAnnotationUnit(Location), Int8PtrTy),
1380    CGM.EmitAnnotationLineNo(Location)
1381  };
1382  return Builder.CreateCall(AnnotationFn, Args);
1383}
1384
1385void CodeGenFunction::EmitVarAnnotations(const VarDecl *D, llvm::Value *V) {
1386  assert(D->hasAttr<AnnotateAttr>() && "no annotate attribute");
1387  // FIXME We create a new bitcast for every annotation because that's what
1388  // llvm-gcc was doing.
1389  for (specific_attr_iterator<AnnotateAttr>
1390       ai = D->specific_attr_begin<AnnotateAttr>(),
1391       ae = D->specific_attr_end<AnnotateAttr>(); ai != ae; ++ai)
1392    EmitAnnotationCall(CGM.getIntrinsic(llvm::Intrinsic::var_annotation),
1393                       Builder.CreateBitCast(V, CGM.Int8PtrTy, V->getName()),
1394                       (*ai)->getAnnotation(), D->getLocation());
1395}
1396
1397llvm::Value *CodeGenFunction::EmitFieldAnnotations(const FieldDecl *D,
1398                                                   llvm::Value *V) {
1399  assert(D->hasAttr<AnnotateAttr>() && "no annotate attribute");
1400  llvm::Type *VTy = V->getType();
1401  llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::ptr_annotation,
1402                                    CGM.Int8PtrTy);
1403
1404  for (specific_attr_iterator<AnnotateAttr>
1405       ai = D->specific_attr_begin<AnnotateAttr>(),
1406       ae = D->specific_attr_end<AnnotateAttr>(); ai != ae; ++ai) {
1407    // FIXME Always emit the cast inst so we can differentiate between
1408    // annotation on the first field of a struct and annotation on the struct
1409    // itself.
1410    if (VTy != CGM.Int8PtrTy)
1411      V = Builder.Insert(new llvm::BitCastInst(V, CGM.Int8PtrTy));
1412    V = EmitAnnotationCall(F, V, (*ai)->getAnnotation(), D->getLocation());
1413    V = Builder.CreateBitCast(V, VTy);
1414  }
1415
1416  return V;
1417}
1418