CodeGenFunction.cpp revision 35415f5132f70ad5097a3514ab84251e10db3664 
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 "CodeGenModule.h"
16#include "CGDebugInfo.h"
17#include "clang/Basic/TargetInfo.h"
18#include "clang/AST/APValue.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 "llvm/Target/TargetData.h"
24using namespace clang;
25using namespace CodeGen;
26
27CodeGenFunction::CodeGenFunction(CodeGenModule &cgm)
28  : BlockFunction(cgm, *this, Builder), CGM(cgm),
29    Target(CGM.getContext().Target),
30    Builder(cgm.getModule().getContext()),
31    DebugInfo(0), IndirectBranch(0),
32    SwitchInsn(0), CaseRangeBlock(0), InvokeDest(0),
33    CXXThisDecl(0), CXXThisValue(0), CXXVTTDecl(0), CXXVTTValue(0),
34    ConditionalBranchLevel(0), TerminateHandler(0), TrapBB(0),
35    UniqueAggrDestructorCount(0) {
36  LLVMIntTy = ConvertType(getContext().IntTy);
37  LLVMPointerWidth = Target.getPointerWidth(0);
38  Exceptions = getContext().getLangOptions().Exceptions;
39  CatchUndefined = getContext().getLangOptions().CatchUndefined;
40  CGM.getMangleContext().startNewFunction();
41}
42
43ASTContext &CodeGenFunction::getContext() const {
44  return CGM.getContext();
45}
46
47
48llvm::BasicBlock *CodeGenFunction::getBasicBlockForLabel(const LabelStmt *S) {
49  llvm::BasicBlock *&BB = LabelMap[S];
50  if (BB) return BB;
51
52  // Create, but don't insert, the new block.
53  return BB = createBasicBlock(S->getName());
54}
55
56llvm::Value *CodeGenFunction::GetAddrOfLocalVar(const VarDecl *VD) {
57  llvm::Value *Res = LocalDeclMap[VD];
58  assert(Res && "Invalid argument to GetAddrOfLocalVar(), no decl!");
59  return Res;
60}
61
62llvm::Constant *
63CodeGenFunction::GetAddrOfStaticLocalVar(const VarDecl *BVD) {
64  return cast<llvm::Constant>(GetAddrOfLocalVar(BVD));
65}
66
67const llvm::Type *CodeGenFunction::ConvertTypeForMem(QualType T) {
68  return CGM.getTypes().ConvertTypeForMem(T);
69}
70
71const llvm::Type *CodeGenFunction::ConvertType(QualType T) {
72  return CGM.getTypes().ConvertType(T);
73}
74
75bool CodeGenFunction::hasAggregateLLVMType(QualType T) {
76  return T->isRecordType() || T->isArrayType() || T->isAnyComplexType() ||
77    T->isMemberFunctionPointerType();
78}
79
80void CodeGenFunction::EmitReturnBlock() {
81  // For cleanliness, we try to avoid emitting the return block for
82  // simple cases.
83  llvm::BasicBlock *CurBB = Builder.GetInsertBlock();
84
85  if (CurBB) {
86    assert(!CurBB->getTerminator() && "Unexpected terminated block.");
87
88    // We have a valid insert point, reuse it if it is empty or there are no
89    // explicit jumps to the return block.
90    if (CurBB->empty() || ReturnBlock->use_empty()) {
91      ReturnBlock->replaceAllUsesWith(CurBB);
92      delete ReturnBlock;
93    } else
94      EmitBlock(ReturnBlock);
95    return;
96  }
97
98  // Otherwise, if the return block is the target of a single direct
99  // branch then we can just put the code in that block instead. This
100  // cleans up functions which started with a unified return block.
101  if (ReturnBlock->hasOneUse()) {
102    llvm::BranchInst *BI =
103      dyn_cast<llvm::BranchInst>(*ReturnBlock->use_begin());
104    if (BI && BI->isUnconditional() && BI->getSuccessor(0) == ReturnBlock) {
105      // Reset insertion point and delete the branch.
106      Builder.SetInsertPoint(BI->getParent());
107      BI->eraseFromParent();
108      delete ReturnBlock;
109      return;
110    }
111  }
112
113  // FIXME: We are at an unreachable point, there is no reason to emit the block
114  // unless it has uses. However, we still need a place to put the debug
115  // region.end for now.
116
117  EmitBlock(ReturnBlock);
118}
119
120void CodeGenFunction::FinishFunction(SourceLocation EndLoc) {
121  assert(BreakContinueStack.empty() &&
122         "mismatched push/pop in break/continue stack!");
123  assert(BlockScopes.empty() &&
124         "did not remove all blocks from block scope map!");
125  assert(CleanupEntries.empty() &&
126         "mismatched push/pop in cleanup stack!");
127
128  // Emit function epilog (to return).
129  EmitReturnBlock();
130
131  // Emit debug descriptor for function end.
132  if (CGDebugInfo *DI = getDebugInfo()) {
133    DI->setLocation(EndLoc);
134    DI->EmitRegionEnd(CurFn, Builder);
135  }
136
137  EmitFunctionEpilog(*CurFnInfo, ReturnValue);
138  EmitEndEHSpec(CurCodeDecl);
139
140  // If someone did an indirect goto, emit the indirect goto block at the end of
141  // the function.
142  if (IndirectBranch) {
143    EmitBlock(IndirectBranch->getParent());
144    Builder.ClearInsertionPoint();
145  }
146
147  // Remove the AllocaInsertPt instruction, which is just a convenience for us.
148  llvm::Instruction *Ptr = AllocaInsertPt;
149  AllocaInsertPt = 0;
150  Ptr->eraseFromParent();
151
152  // If someone took the address of a label but never did an indirect goto, we
153  // made a zero entry PHI node, which is illegal, zap it now.
154  if (IndirectBranch) {
155    llvm::PHINode *PN = cast<llvm::PHINode>(IndirectBranch->getAddress());
156    if (PN->getNumIncomingValues() == 0) {
157      PN->replaceAllUsesWith(llvm::UndefValue::get(PN->getType()));
158      PN->eraseFromParent();
159    }
160  }
161}
162
163void CodeGenFunction::StartFunction(GlobalDecl GD, QualType RetTy,
164                                    llvm::Function *Fn,
165                                    const FunctionArgList &Args,
166                                    SourceLocation StartLoc) {
167  const Decl *D = GD.getDecl();
168
169  DidCallStackSave = false;
170  CurCodeDecl = CurFuncDecl = D;
171  FnRetTy = RetTy;
172  CurFn = Fn;
173  assert(CurFn->isDeclaration() && "Function already has body?");
174
175  // Pass inline keyword to optimizer if it appears explicitly on any
176  // declaration.
177  if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D))
178    for (FunctionDecl::redecl_iterator RI = FD->redecls_begin(),
179           RE = FD->redecls_end(); RI != RE; ++RI)
180      if (RI->isInlineSpecified()) {
181        Fn->addFnAttr(llvm::Attribute::InlineHint);
182        break;
183      }
184
185  llvm::BasicBlock *EntryBB = createBasicBlock("entry", CurFn);
186
187  // Create a marker to make it easy to insert allocas into the entryblock
188  // later.  Don't create this with the builder, because we don't want it
189  // folded.
190  llvm::Value *Undef = llvm::UndefValue::get(llvm::Type::getInt32Ty(VMContext));
191  AllocaInsertPt = new llvm::BitCastInst(Undef,
192                                         llvm::Type::getInt32Ty(VMContext), "",
193                                         EntryBB);
194  if (Builder.isNamePreserving())
195    AllocaInsertPt->setName("allocapt");
196
197  ReturnBlock = createBasicBlock("return");
198
199  Builder.SetInsertPoint(EntryBB);
200
201  QualType FnType = getContext().getFunctionType(RetTy, 0, 0, false, 0,
202                                                 false, false, 0, 0,
203                                                 /*FIXME?*/
204                                                 FunctionType::ExtInfo());
205
206  // Emit subprogram debug descriptor.
207  if (CGDebugInfo *DI = getDebugInfo()) {
208    DI->setLocation(StartLoc);
209    DI->EmitFunctionStart(GD, FnType, CurFn, Builder);
210  }
211
212  // FIXME: Leaked.
213  // CC info is ignored, hopefully?
214  CurFnInfo = &CGM.getTypes().getFunctionInfo(FnRetTy, Args,
215                                              FunctionType::ExtInfo());
216
217  if (RetTy->isVoidType()) {
218    // Void type; nothing to return.
219    ReturnValue = 0;
220  } else if (CurFnInfo->getReturnInfo().getKind() == ABIArgInfo::Indirect &&
221             hasAggregateLLVMType(CurFnInfo->getReturnType())) {
222    // Indirect aggregate return; emit returned value directly into sret slot.
223    // This reduces code size, and affects correctness in C++.
224    ReturnValue = CurFn->arg_begin();
225  } else {
226    ReturnValue = CreateIRTemp(RetTy, "retval");
227  }
228
229  EmitStartEHSpec(CurCodeDecl);
230  EmitFunctionProlog(*CurFnInfo, CurFn, Args);
231
232  if (CXXThisDecl)
233    CXXThisValue = Builder.CreateLoad(LocalDeclMap[CXXThisDecl], "this");
234  if (CXXVTTDecl)
235    CXXVTTValue = Builder.CreateLoad(LocalDeclMap[CXXVTTDecl], "vtt");
236
237  // If any of the arguments have a variably modified type, make sure to
238  // emit the type size.
239  for (FunctionArgList::const_iterator i = Args.begin(), e = Args.end();
240       i != e; ++i) {
241    QualType Ty = i->second;
242
243    if (Ty->isVariablyModifiedType())
244      EmitVLASize(Ty);
245  }
246}
247
248void CodeGenFunction::EmitFunctionBody(FunctionArgList &Args) {
249  const FunctionDecl *FD = cast<FunctionDecl>(CurGD.getDecl());
250  assert(FD->getBody());
251  EmitStmt(FD->getBody());
252}
253
254void CodeGenFunction::GenerateCode(GlobalDecl GD, llvm::Function *Fn) {
255  const FunctionDecl *FD = cast<FunctionDecl>(GD.getDecl());
256
257  // Check if we should generate debug info for this function.
258  if (CGM.getDebugInfo() && !FD->hasAttr<NoDebugAttr>())
259    DebugInfo = CGM.getDebugInfo();
260
261  FunctionArgList Args;
262
263  CurGD = GD;
264  if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD)) {
265    if (MD->isInstance()) {
266      // Create the implicit 'this' decl.
267      // FIXME: I'm not entirely sure I like using a fake decl just for code
268      // generation. Maybe we can come up with a better way?
269      CXXThisDecl = ImplicitParamDecl::Create(getContext(), 0,
270                                              FD->getLocation(),
271                                              &getContext().Idents.get("this"),
272                                              MD->getThisType(getContext()));
273      Args.push_back(std::make_pair(CXXThisDecl, CXXThisDecl->getType()));
274
275      // Check if we need a VTT parameter as well.
276      if (CodeGenVTables::needsVTTParameter(GD)) {
277        // FIXME: The comment about using a fake decl above applies here too.
278        QualType T = getContext().getPointerType(getContext().VoidPtrTy);
279        CXXVTTDecl =
280          ImplicitParamDecl::Create(getContext(), 0, FD->getLocation(),
281                                    &getContext().Idents.get("vtt"), T);
282        Args.push_back(std::make_pair(CXXVTTDecl, CXXVTTDecl->getType()));
283      }
284    }
285  }
286
287  if (FD->getNumParams()) {
288    const FunctionProtoType* FProto = FD->getType()->getAs<FunctionProtoType>();
289    assert(FProto && "Function def must have prototype!");
290
291    for (unsigned i = 0, e = FD->getNumParams(); i != e; ++i)
292      Args.push_back(std::make_pair(FD->getParamDecl(i),
293                                    FProto->getArgType(i)));
294  }
295
296  SourceRange BodyRange;
297  if (Stmt *Body = FD->getBody()) BodyRange = Body->getSourceRange();
298
299  // Emit the standard function prologue.
300  StartFunction(GD, FD->getResultType(), Fn, Args, BodyRange.getBegin());
301
302  // Generate the body of the function.
303  if (isa<CXXDestructorDecl>(FD))
304    EmitDestructorBody(Args);
305  else if (isa<CXXConstructorDecl>(FD))
306    EmitConstructorBody(Args);
307  else
308    EmitFunctionBody(Args);
309
310  // Emit the standard function epilogue.
311  FinishFunction(BodyRange.getEnd());
312
313  // Destroy the 'this' declaration.
314  if (CXXThisDecl)
315    CXXThisDecl->Destroy(getContext());
316
317  // Destroy the VTT declaration.
318  if (CXXVTTDecl)
319    CXXVTTDecl->Destroy(getContext());
320}
321
322/// ContainsLabel - Return true if the statement contains a label in it.  If
323/// this statement is not executed normally, it not containing a label means
324/// that we can just remove the code.
325bool CodeGenFunction::ContainsLabel(const Stmt *S, bool IgnoreCaseStmts) {
326  // Null statement, not a label!
327  if (S == 0) return false;
328
329  // If this is a label, we have to emit the code, consider something like:
330  // if (0) {  ...  foo:  bar(); }  goto foo;
331  if (isa<LabelStmt>(S))
332    return true;
333
334  // If this is a case/default statement, and we haven't seen a switch, we have
335  // to emit the code.
336  if (isa<SwitchCase>(S) && !IgnoreCaseStmts)
337    return true;
338
339  // If this is a switch statement, we want to ignore cases below it.
340  if (isa<SwitchStmt>(S))
341    IgnoreCaseStmts = true;
342
343  // Scan subexpressions for verboten labels.
344  for (Stmt::const_child_iterator I = S->child_begin(), E = S->child_end();
345       I != E; ++I)
346    if (ContainsLabel(*I, IgnoreCaseStmts))
347      return true;
348
349  return false;
350}
351
352
353/// ConstantFoldsToSimpleInteger - If the sepcified expression does not fold to
354/// a constant, or if it does but contains a label, return 0.  If it constant
355/// folds to 'true' and does not contain a label, return 1, if it constant folds
356/// to 'false' and does not contain a label, return -1.
357int CodeGenFunction::ConstantFoldsToSimpleInteger(const Expr *Cond) {
358  // FIXME: Rename and handle conversion of other evaluatable things
359  // to bool.
360  Expr::EvalResult Result;
361  if (!Cond->Evaluate(Result, getContext()) || !Result.Val.isInt() ||
362      Result.HasSideEffects)
363    return 0;  // Not foldable, not integer or not fully evaluatable.
364
365  if (CodeGenFunction::ContainsLabel(Cond))
366    return 0;  // Contains a label.
367
368  return Result.Val.getInt().getBoolValue() ? 1 : -1;
369}
370
371
372/// EmitBranchOnBoolExpr - Emit a branch on a boolean condition (e.g. for an if
373/// statement) to the specified blocks.  Based on the condition, this might try
374/// to simplify the codegen of the conditional based on the branch.
375///
376void CodeGenFunction::EmitBranchOnBoolExpr(const Expr *Cond,
377                                           llvm::BasicBlock *TrueBlock,
378                                           llvm::BasicBlock *FalseBlock) {
379  if (const ParenExpr *PE = dyn_cast<ParenExpr>(Cond))
380    return EmitBranchOnBoolExpr(PE->getSubExpr(), TrueBlock, FalseBlock);
381
382  if (const BinaryOperator *CondBOp = dyn_cast<BinaryOperator>(Cond)) {
383    // Handle X && Y in a condition.
384    if (CondBOp->getOpcode() == BinaryOperator::LAnd) {
385      // If we have "1 && X", simplify the code.  "0 && X" would have constant
386      // folded if the case was simple enough.
387      if (ConstantFoldsToSimpleInteger(CondBOp->getLHS()) == 1) {
388        // br(1 && X) -> br(X).
389        return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock);
390      }
391
392      // If we have "X && 1", simplify the code to use an uncond branch.
393      // "X && 0" would have been constant folded to 0.
394      if (ConstantFoldsToSimpleInteger(CondBOp->getRHS()) == 1) {
395        // br(X && 1) -> br(X).
396        return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock);
397      }
398
399      // Emit the LHS as a conditional.  If the LHS conditional is false, we
400      // want to jump to the FalseBlock.
401      llvm::BasicBlock *LHSTrue = createBasicBlock("land.lhs.true");
402      EmitBranchOnBoolExpr(CondBOp->getLHS(), LHSTrue, FalseBlock);
403      EmitBlock(LHSTrue);
404
405      // Any temporaries created here are conditional.
406      BeginConditionalBranch();
407      EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock);
408      EndConditionalBranch();
409
410      return;
411    } else if (CondBOp->getOpcode() == BinaryOperator::LOr) {
412      // If we have "0 || X", simplify the code.  "1 || X" would have constant
413      // folded if the case was simple enough.
414      if (ConstantFoldsToSimpleInteger(CondBOp->getLHS()) == -1) {
415        // br(0 || X) -> br(X).
416        return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock);
417      }
418
419      // If we have "X || 0", simplify the code to use an uncond branch.
420      // "X || 1" would have been constant folded to 1.
421      if (ConstantFoldsToSimpleInteger(CondBOp->getRHS()) == -1) {
422        // br(X || 0) -> br(X).
423        return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock);
424      }
425
426      // Emit the LHS as a conditional.  If the LHS conditional is true, we
427      // want to jump to the TrueBlock.
428      llvm::BasicBlock *LHSFalse = createBasicBlock("lor.lhs.false");
429      EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, LHSFalse);
430      EmitBlock(LHSFalse);
431
432      // Any temporaries created here are conditional.
433      BeginConditionalBranch();
434      EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock);
435      EndConditionalBranch();
436
437      return;
438    }
439  }
440
441  if (const UnaryOperator *CondUOp = dyn_cast<UnaryOperator>(Cond)) {
442    // br(!x, t, f) -> br(x, f, t)
443    if (CondUOp->getOpcode() == UnaryOperator::LNot)
444      return EmitBranchOnBoolExpr(CondUOp->getSubExpr(), FalseBlock, TrueBlock);
445  }
446
447  if (const ConditionalOperator *CondOp = dyn_cast<ConditionalOperator>(Cond)) {
448    // Handle ?: operator.
449
450    // Just ignore GNU ?: extension.
451    if (CondOp->getLHS()) {
452      // br(c ? x : y, t, f) -> br(c, br(x, t, f), br(y, t, f))
453      llvm::BasicBlock *LHSBlock = createBasicBlock("cond.true");
454      llvm::BasicBlock *RHSBlock = createBasicBlock("cond.false");
455      EmitBranchOnBoolExpr(CondOp->getCond(), LHSBlock, RHSBlock);
456      EmitBlock(LHSBlock);
457      EmitBranchOnBoolExpr(CondOp->getLHS(), TrueBlock, FalseBlock);
458      EmitBlock(RHSBlock);
459      EmitBranchOnBoolExpr(CondOp->getRHS(), TrueBlock, FalseBlock);
460      return;
461    }
462  }
463
464  // Emit the code with the fully general case.
465  llvm::Value *CondV = EvaluateExprAsBool(Cond);
466  Builder.CreateCondBr(CondV, TrueBlock, FalseBlock);
467}
468
469/// ErrorUnsupported - Print out an error that codegen doesn't support the
470/// specified stmt yet.
471void CodeGenFunction::ErrorUnsupported(const Stmt *S, const char *Type,
472                                       bool OmitOnError) {
473  CGM.ErrorUnsupported(S, Type, OmitOnError);
474}
475
476void
477CodeGenFunction::EmitNullInitialization(llvm::Value *DestPtr, QualType Ty) {
478  // If the type contains a pointer to data member we can't memset it to zero.
479  // Instead, create a null constant and copy it to the destination.
480  if (CGM.getTypes().ContainsPointerToDataMember(Ty)) {
481    llvm::Constant *NullConstant = CGM.EmitNullConstant(Ty);
482
483    llvm::GlobalVariable *NullVariable =
484      new llvm::GlobalVariable(CGM.getModule(), NullConstant->getType(),
485                               /*isConstant=*/true,
486                               llvm::GlobalVariable::PrivateLinkage,
487                               NullConstant, llvm::Twine());
488    EmitAggregateCopy(DestPtr, NullVariable, Ty, /*isVolatile=*/false);
489    return;
490  }
491
492
493  // Ignore empty classes in C++.
494  if (getContext().getLangOptions().CPlusPlus) {
495    if (const RecordType *RT = Ty->getAs<RecordType>()) {
496      if (cast<CXXRecordDecl>(RT->getDecl())->isEmpty())
497        return;
498    }
499  }
500
501  // Otherwise, just memset the whole thing to zero.  This is legal
502  // because in LLVM, all default initializers (other than the ones we just
503  // handled above) are guaranteed to have a bit pattern of all zeros.
504  const llvm::Type *BP = llvm::Type::getInt8PtrTy(VMContext);
505  if (DestPtr->getType() != BP)
506    DestPtr = Builder.CreateBitCast(DestPtr, BP, "tmp");
507
508  // Get size and alignment info for this aggregate.
509  std::pair<uint64_t, unsigned> TypeInfo = getContext().getTypeInfo(Ty);
510
511  // Don't bother emitting a zero-byte memset.
512  if (TypeInfo.first == 0)
513    return;
514
515  // FIXME: Handle variable sized types.
516  const llvm::Type *IntPtr = llvm::IntegerType::get(VMContext,
517                                                    LLVMPointerWidth);
518
519  Builder.CreateCall5(CGM.getMemSetFn(BP, IntPtr), DestPtr,
520                 llvm::Constant::getNullValue(llvm::Type::getInt8Ty(VMContext)),
521                      // TypeInfo.first describes size in bits.
522                      llvm::ConstantInt::get(IntPtr, TypeInfo.first/8),
523                      llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext),
524                                             TypeInfo.second/8),
525                      llvm::ConstantInt::get(llvm::Type::getInt1Ty(VMContext),
526                                             0));
527}
528
529llvm::BlockAddress *CodeGenFunction::GetAddrOfLabel(const LabelStmt *L) {
530  // Make sure that there is a block for the indirect goto.
531  if (IndirectBranch == 0)
532    GetIndirectGotoBlock();
533
534  llvm::BasicBlock *BB = getBasicBlockForLabel(L);
535
536  // Make sure the indirect branch includes all of the address-taken blocks.
537  IndirectBranch->addDestination(BB);
538  return llvm::BlockAddress::get(CurFn, BB);
539}
540
541llvm::BasicBlock *CodeGenFunction::GetIndirectGotoBlock() {
542  // If we already made the indirect branch for indirect goto, return its block.
543  if (IndirectBranch) return IndirectBranch->getParent();
544
545  CGBuilderTy TmpBuilder(createBasicBlock("indirectgoto"));
546
547  const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(VMContext);
548
549  // Create the PHI node that indirect gotos will add entries to.
550  llvm::Value *DestVal = TmpBuilder.CreatePHI(Int8PtrTy, "indirect.goto.dest");
551
552  // Create the indirect branch instruction.
553  IndirectBranch = TmpBuilder.CreateIndirectBr(DestVal);
554  return IndirectBranch->getParent();
555}
556
557llvm::Value *CodeGenFunction::GetVLASize(const VariableArrayType *VAT) {
558  llvm::Value *&SizeEntry = VLASizeMap[VAT->getSizeExpr()];
559
560  assert(SizeEntry && "Did not emit size for type");
561  return SizeEntry;
562}
563
564llvm::Value *CodeGenFunction::EmitVLASize(QualType Ty) {
565  assert(Ty->isVariablyModifiedType() &&
566         "Must pass variably modified type to EmitVLASizes!");
567
568  EnsureInsertPoint();
569
570  if (const VariableArrayType *VAT = getContext().getAsVariableArrayType(Ty)) {
571    llvm::Value *&SizeEntry = VLASizeMap[VAT->getSizeExpr()];
572
573    if (!SizeEntry) {
574      const llvm::Type *SizeTy = ConvertType(getContext().getSizeType());
575
576      // Get the element size;
577      QualType ElemTy = VAT->getElementType();
578      llvm::Value *ElemSize;
579      if (ElemTy->isVariableArrayType())
580        ElemSize = EmitVLASize(ElemTy);
581      else
582        ElemSize = llvm::ConstantInt::get(SizeTy,
583            getContext().getTypeSizeInChars(ElemTy).getQuantity());
584
585      llvm::Value *NumElements = EmitScalarExpr(VAT->getSizeExpr());
586      NumElements = Builder.CreateIntCast(NumElements, SizeTy, false, "tmp");
587
588      SizeEntry = Builder.CreateMul(ElemSize, NumElements);
589    }
590
591    return SizeEntry;
592  }
593
594  if (const ArrayType *AT = dyn_cast<ArrayType>(Ty)) {
595    EmitVLASize(AT->getElementType());
596    return 0;
597  }
598
599  const PointerType *PT = Ty->getAs<PointerType>();
600  assert(PT && "unknown VM type!");
601  EmitVLASize(PT->getPointeeType());
602  return 0;
603}
604
605llvm::Value* CodeGenFunction::EmitVAListRef(const Expr* E) {
606  if (CGM.getContext().getBuiltinVaListType()->isArrayType()) {
607    return EmitScalarExpr(E);
608  }
609  return EmitLValue(E).getAddress();
610}
611
612void CodeGenFunction::PushCleanupBlock(llvm::BasicBlock *CleanupEntryBlock,
613                                       llvm::BasicBlock *CleanupExitBlock,
614                                       llvm::BasicBlock *PreviousInvokeDest,
615                                       bool EHOnly) {
616  CleanupEntries.push_back(CleanupEntry(CleanupEntryBlock, CleanupExitBlock,
617                                        PreviousInvokeDest, EHOnly));
618}
619
620void CodeGenFunction::EmitCleanupBlocks(size_t OldCleanupStackSize) {
621  assert(CleanupEntries.size() >= OldCleanupStackSize &&
622         "Cleanup stack mismatch!");
623
624  while (CleanupEntries.size() > OldCleanupStackSize)
625    EmitCleanupBlock();
626}
627
628CodeGenFunction::CleanupBlockInfo CodeGenFunction::PopCleanupBlock() {
629  CleanupEntry &CE = CleanupEntries.back();
630
631  llvm::BasicBlock *CleanupEntryBlock = CE.CleanupEntryBlock;
632
633  std::vector<llvm::BasicBlock *> Blocks;
634  std::swap(Blocks, CE.Blocks);
635
636  std::vector<llvm::BranchInst *> BranchFixups;
637  std::swap(BranchFixups, CE.BranchFixups);
638
639  bool EHOnly = CE.EHOnly;
640
641  setInvokeDest(CE.PreviousInvokeDest);
642
643  CleanupEntries.pop_back();
644
645  // Check if any branch fixups pointed to the scope we just popped. If so,
646  // we can remove them.
647  for (size_t i = 0, e = BranchFixups.size(); i != e; ++i) {
648    llvm::BasicBlock *Dest = BranchFixups[i]->getSuccessor(0);
649    BlockScopeMap::iterator I = BlockScopes.find(Dest);
650
651    if (I == BlockScopes.end())
652      continue;
653
654    assert(I->second <= CleanupEntries.size() && "Invalid branch fixup!");
655
656    if (I->second == CleanupEntries.size()) {
657      // We don't need to do this branch fixup.
658      BranchFixups[i] = BranchFixups.back();
659      BranchFixups.pop_back();
660      i--;
661      e--;
662      continue;
663    }
664  }
665
666  llvm::BasicBlock *SwitchBlock = CE.CleanupExitBlock;
667  llvm::BasicBlock *EndBlock = 0;
668  if (!BranchFixups.empty()) {
669    if (!SwitchBlock)
670      SwitchBlock = createBasicBlock("cleanup.switch");
671    EndBlock = createBasicBlock("cleanup.end");
672
673    llvm::BasicBlock *CurBB = Builder.GetInsertBlock();
674
675    Builder.SetInsertPoint(SwitchBlock);
676
677    llvm::Value *DestCodePtr
678      = CreateTempAlloca(llvm::Type::getInt32Ty(VMContext),
679                         "cleanup.dst");
680    llvm::Value *DestCode = Builder.CreateLoad(DestCodePtr, "tmp");
681
682    // Create a switch instruction to determine where to jump next.
683    llvm::SwitchInst *SI = Builder.CreateSwitch(DestCode, EndBlock,
684                                                BranchFixups.size());
685
686    // Restore the current basic block (if any)
687    if (CurBB) {
688      Builder.SetInsertPoint(CurBB);
689
690      // If we had a current basic block, we also need to emit an instruction
691      // to initialize the cleanup destination.
692      Builder.CreateStore(llvm::Constant::getNullValue(llvm::Type::getInt32Ty(VMContext)),
693                          DestCodePtr);
694    } else
695      Builder.ClearInsertionPoint();
696
697    for (size_t i = 0, e = BranchFixups.size(); i != e; ++i) {
698      llvm::BranchInst *BI = BranchFixups[i];
699      llvm::BasicBlock *Dest = BI->getSuccessor(0);
700
701      // Fixup the branch instruction to point to the cleanup block.
702      BI->setSuccessor(0, CleanupEntryBlock);
703
704      if (CleanupEntries.empty()) {
705        llvm::ConstantInt *ID;
706
707        // Check if we already have a destination for this block.
708        if (Dest == SI->getDefaultDest())
709          ID = llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext), 0);
710        else {
711          ID = SI->findCaseDest(Dest);
712          if (!ID) {
713            // No code found, get a new unique one by using the number of
714            // switch successors.
715            ID = llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext),
716                                        SI->getNumSuccessors());
717            SI->addCase(ID, Dest);
718          }
719        }
720
721        // Store the jump destination before the branch instruction.
722        new llvm::StoreInst(ID, DestCodePtr, BI);
723      } else {
724        // We need to jump through another cleanup block. Create a pad block
725        // with a branch instruction that jumps to the final destination and add
726        // it as a branch fixup to the current cleanup scope.
727
728        // Create the pad block.
729        llvm::BasicBlock *CleanupPad = createBasicBlock("cleanup.pad", CurFn);
730
731        // Create a unique case ID.
732        llvm::ConstantInt *ID
733          = llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext),
734                                   SI->getNumSuccessors());
735
736        // Store the jump destination before the branch instruction.
737        new llvm::StoreInst(ID, DestCodePtr, BI);
738
739        // Add it as the destination.
740        SI->addCase(ID, CleanupPad);
741
742        // Create the branch to the final destination.
743        llvm::BranchInst *BI = llvm::BranchInst::Create(Dest);
744        CleanupPad->getInstList().push_back(BI);
745
746        // And add it as a branch fixup.
747        CleanupEntries.back().BranchFixups.push_back(BI);
748      }
749    }
750  }
751
752  // Remove all blocks from the block scope map.
753  for (size_t i = 0, e = Blocks.size(); i != e; ++i) {
754    assert(BlockScopes.count(Blocks[i]) &&
755           "Did not find block in scope map!");
756
757    BlockScopes.erase(Blocks[i]);
758  }
759
760  return CleanupBlockInfo(CleanupEntryBlock, SwitchBlock, EndBlock, EHOnly);
761}
762
763void CodeGenFunction::EmitCleanupBlock() {
764  CleanupBlockInfo Info = PopCleanupBlock();
765
766  if (Info.EHOnly) {
767    // FIXME: Add this to the exceptional edge
768    if (Info.CleanupBlock->getNumUses() == 0)
769      delete Info.CleanupBlock;
770    return;
771  }
772
773  //  Scrub debug location info.
774  for (llvm::BasicBlock::iterator LBI = Info.CleanupBlock->begin(),
775         LBE = Info.CleanupBlock->end(); LBI != LBE; ++LBI)
776    Builder.SetInstDebugLocation(LBI);
777
778  llvm::BasicBlock *CurBB = Builder.GetInsertBlock();
779  if (CurBB && !CurBB->getTerminator() &&
780      Info.CleanupBlock->getNumUses() == 0) {
781    CurBB->getInstList().splice(CurBB->end(), Info.CleanupBlock->getInstList());
782    delete Info.CleanupBlock;
783  } else
784    EmitBlock(Info.CleanupBlock);
785
786  if (Info.SwitchBlock)
787    EmitBlock(Info.SwitchBlock);
788  if (Info.EndBlock)
789    EmitBlock(Info.EndBlock);
790}
791
792void CodeGenFunction::AddBranchFixup(llvm::BranchInst *BI) {
793  assert(!CleanupEntries.empty() &&
794         "Trying to add branch fixup without cleanup block!");
795
796  // FIXME: We could be more clever here and check if there's already a branch
797  // fixup for this destination and recycle it.
798  CleanupEntries.back().BranchFixups.push_back(BI);
799}
800
801void CodeGenFunction::EmitBranchThroughCleanup(llvm::BasicBlock *Dest) {
802  if (!HaveInsertPoint())
803    return;
804
805  llvm::BranchInst* BI = Builder.CreateBr(Dest);
806
807  Builder.ClearInsertionPoint();
808
809  // The stack is empty, no need to do any cleanup.
810  if (CleanupEntries.empty())
811    return;
812
813  if (!Dest->getParent()) {
814    // We are trying to branch to a block that hasn't been inserted yet.
815    AddBranchFixup(BI);
816    return;
817  }
818
819  BlockScopeMap::iterator I = BlockScopes.find(Dest);
820  if (I == BlockScopes.end()) {
821    // We are trying to jump to a block that is outside of any cleanup scope.
822    AddBranchFixup(BI);
823    return;
824  }
825
826  assert(I->second < CleanupEntries.size() &&
827         "Trying to branch into cleanup region");
828
829  if (I->second == CleanupEntries.size() - 1) {
830    // We have a branch to a block in the same scope.
831    return;
832  }
833
834  AddBranchFixup(BI);
835}
836