CodeGenFunction.cpp revision 34161996e5bec20bcc3a97894a3a38f2d0f56c72 
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 "clang/Frontend/CodeGenOptions.h"
24#include "llvm/Target/TargetData.h"
25#include "llvm/Intrinsics.h"
26using namespace clang;
27using namespace CodeGen;
28
29CodeGenFunction::CodeGenFunction(CodeGenModule &cgm)
30  : BlockFunction(cgm, *this, Builder), CGM(cgm),
31    Target(CGM.getContext().Target),
32    Builder(cgm.getModule().getContext()),
33    DebugInfo(0), IndirectBranch(0),
34    SwitchInsn(0), CaseRangeBlock(0), InvokeDest(0),
35    CXXThisDecl(0), CXXThisValue(0), CXXVTTDecl(0), CXXVTTValue(0),
36    ConditionalBranchLevel(0), TerminateHandler(0), TrapBB(0) {
37
38  // Get some frequently used types.
39  LLVMPointerWidth = Target.getPointerWidth(0);
40  llvm::LLVMContext &LLVMContext = CGM.getLLVMContext();
41  IntPtrTy = llvm::IntegerType::get(LLVMContext, LLVMPointerWidth);
42  Int32Ty  = llvm::Type::getInt32Ty(LLVMContext);
43  Int64Ty  = llvm::Type::getInt64Ty(LLVMContext);
44
45  Exceptions = getContext().getLangOptions().Exceptions;
46  CatchUndefined = getContext().getLangOptions().CatchUndefined;
47  CGM.getMangleContext().startNewFunction();
48}
49
50ASTContext &CodeGenFunction::getContext() const {
51  return CGM.getContext();
52}
53
54
55llvm::BasicBlock *CodeGenFunction::getBasicBlockForLabel(const LabelStmt *S) {
56  llvm::BasicBlock *&BB = LabelMap[S];
57  if (BB) return BB;
58
59  // Create, but don't insert, the new block.
60  return BB = createBasicBlock(S->getName());
61}
62
63llvm::Value *CodeGenFunction::GetAddrOfLocalVar(const VarDecl *VD) {
64  llvm::Value *Res = LocalDeclMap[VD];
65  assert(Res && "Invalid argument to GetAddrOfLocalVar(), no decl!");
66  return Res;
67}
68
69llvm::Constant *
70CodeGenFunction::GetAddrOfStaticLocalVar(const VarDecl *BVD) {
71  return cast<llvm::Constant>(GetAddrOfLocalVar(BVD));
72}
73
74const llvm::Type *CodeGenFunction::ConvertTypeForMem(QualType T) {
75  return CGM.getTypes().ConvertTypeForMem(T);
76}
77
78const llvm::Type *CodeGenFunction::ConvertType(QualType T) {
79  return CGM.getTypes().ConvertType(T);
80}
81
82bool CodeGenFunction::hasAggregateLLVMType(QualType T) {
83  return T->isRecordType() || T->isArrayType() || T->isAnyComplexType() ||
84    T->isMemberFunctionPointerType();
85}
86
87void CodeGenFunction::EmitReturnBlock() {
88  // For cleanliness, we try to avoid emitting the return block for
89  // simple cases.
90  llvm::BasicBlock *CurBB = Builder.GetInsertBlock();
91
92  if (CurBB) {
93    assert(!CurBB->getTerminator() && "Unexpected terminated block.");
94
95    // We have a valid insert point, reuse it if it is empty or there are no
96    // explicit jumps to the return block.
97    if (CurBB->empty() || ReturnBlock->use_empty()) {
98      ReturnBlock->replaceAllUsesWith(CurBB);
99      delete ReturnBlock;
100    } else
101      EmitBlock(ReturnBlock);
102    return;
103  }
104
105  // Otherwise, if the return block is the target of a single direct
106  // branch then we can just put the code in that block instead. This
107  // cleans up functions which started with a unified return block.
108  if (ReturnBlock->hasOneUse()) {
109    llvm::BranchInst *BI =
110      dyn_cast<llvm::BranchInst>(*ReturnBlock->use_begin());
111    if (BI && BI->isUnconditional() && BI->getSuccessor(0) == ReturnBlock) {
112      // Reset insertion point and delete the branch.
113      Builder.SetInsertPoint(BI->getParent());
114      BI->eraseFromParent();
115      delete ReturnBlock;
116      return;
117    }
118  }
119
120  // FIXME: We are at an unreachable point, there is no reason to emit the block
121  // unless it has uses. However, we still need a place to put the debug
122  // region.end for now.
123
124  EmitBlock(ReturnBlock);
125}
126
127void CodeGenFunction::FinishFunction(SourceLocation EndLoc) {
128  assert(BreakContinueStack.empty() &&
129         "mismatched push/pop in break/continue stack!");
130  assert(BlockScopes.empty() &&
131         "did not remove all blocks from block scope map!");
132  assert(CleanupEntries.empty() &&
133         "mismatched push/pop in cleanup stack!");
134
135  // Emit function epilog (to return).
136  EmitReturnBlock();
137
138  EmitFunctionInstrumentation("__cyg_profile_func_exit");
139
140  // Emit debug descriptor for function end.
141  if (CGDebugInfo *DI = getDebugInfo()) {
142    DI->setLocation(EndLoc);
143    DI->EmitRegionEnd(CurFn, Builder);
144  }
145
146  EmitFunctionEpilog(*CurFnInfo);
147  EmitEndEHSpec(CurCodeDecl);
148
149  // If someone did an indirect goto, emit the indirect goto block at the end of
150  // the function.
151  if (IndirectBranch) {
152    EmitBlock(IndirectBranch->getParent());
153    Builder.ClearInsertionPoint();
154  }
155
156  // Remove the AllocaInsertPt instruction, which is just a convenience for us.
157  llvm::Instruction *Ptr = AllocaInsertPt;
158  AllocaInsertPt = 0;
159  Ptr->eraseFromParent();
160
161  // If someone took the address of a label but never did an indirect goto, we
162  // made a zero entry PHI node, which is illegal, zap it now.
163  if (IndirectBranch) {
164    llvm::PHINode *PN = cast<llvm::PHINode>(IndirectBranch->getAddress());
165    if (PN->getNumIncomingValues() == 0) {
166      PN->replaceAllUsesWith(llvm::UndefValue::get(PN->getType()));
167      PN->eraseFromParent();
168    }
169  }
170}
171
172/// ShouldInstrumentFunction - Return true if the current function should be
173/// instrumented with __cyg_profile_func_* calls
174bool CodeGenFunction::ShouldInstrumentFunction() {
175  if (!CGM.getCodeGenOpts().InstrumentFunctions)
176    return false;
177  if (CurFuncDecl->hasAttr<NoInstrumentFunctionAttr>())
178    return false;
179  return true;
180}
181
182/// EmitFunctionInstrumentation - Emit LLVM code to call the specified
183/// instrumentation function with the current function and the call site, if
184/// function instrumentation is enabled.
185void CodeGenFunction::EmitFunctionInstrumentation(const char *Fn) {
186  if (!ShouldInstrumentFunction())
187    return;
188
189  const llvm::PointerType *PointerTy;
190  const llvm::FunctionType *FunctionTy;
191  std::vector<const llvm::Type*> ProfileFuncArgs;
192
193  // void __cyg_profile_func_{enter,exit} (void *this_fn, void *call_site);
194  PointerTy = llvm::Type::getInt8PtrTy(VMContext);
195  ProfileFuncArgs.push_back(PointerTy);
196  ProfileFuncArgs.push_back(PointerTy);
197  FunctionTy = llvm::FunctionType::get(
198    llvm::Type::getVoidTy(VMContext),
199    ProfileFuncArgs, false);
200
201  llvm::Constant *F = CGM.CreateRuntimeFunction(FunctionTy, Fn);
202  llvm::CallInst *CallSite = Builder.CreateCall(
203    CGM.getIntrinsic(llvm::Intrinsic::returnaddress, 0, 0),
204    llvm::ConstantInt::get(Int32Ty, 0),
205    "callsite");
206
207  Builder.CreateCall2(F,
208                      llvm::ConstantExpr::getBitCast(CurFn, PointerTy),
209                      CallSite);
210}
211
212void CodeGenFunction::StartFunction(GlobalDecl GD, QualType RetTy,
213                                    llvm::Function *Fn,
214                                    const FunctionArgList &Args,
215                                    SourceLocation StartLoc) {
216  const Decl *D = GD.getDecl();
217
218  DidCallStackSave = false;
219  CurCodeDecl = CurFuncDecl = D;
220  FnRetTy = RetTy;
221  CurFn = Fn;
222  assert(CurFn->isDeclaration() && "Function already has body?");
223
224  // Pass inline keyword to optimizer if it appears explicitly on any
225  // declaration.
226  if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D))
227    for (FunctionDecl::redecl_iterator RI = FD->redecls_begin(),
228           RE = FD->redecls_end(); RI != RE; ++RI)
229      if (RI->isInlineSpecified()) {
230        Fn->addFnAttr(llvm::Attribute::InlineHint);
231        break;
232      }
233
234  llvm::BasicBlock *EntryBB = createBasicBlock("entry", CurFn);
235
236  // Create a marker to make it easy to insert allocas into the entryblock
237  // later.  Don't create this with the builder, because we don't want it
238  // folded.
239  llvm::Value *Undef = llvm::UndefValue::get(Int32Ty);
240  AllocaInsertPt = new llvm::BitCastInst(Undef, Int32Ty, "", EntryBB);
241  if (Builder.isNamePreserving())
242    AllocaInsertPt->setName("allocapt");
243
244  ReturnBlock = createBasicBlock("return");
245
246  Builder.SetInsertPoint(EntryBB);
247
248  QualType FnType = getContext().getFunctionType(RetTy, 0, 0, false, 0,
249                                                 false, false, 0, 0,
250                                                 /*FIXME?*/
251                                                 FunctionType::ExtInfo());
252
253  // Emit subprogram debug descriptor.
254  if (CGDebugInfo *DI = getDebugInfo()) {
255    DI->setLocation(StartLoc);
256    DI->EmitFunctionStart(GD, FnType, CurFn, Builder);
257  }
258
259  EmitFunctionInstrumentation("__cyg_profile_func_enter");
260
261  // FIXME: Leaked.
262  // CC info is ignored, hopefully?
263  CurFnInfo = &CGM.getTypes().getFunctionInfo(FnRetTy, Args,
264                                              FunctionType::ExtInfo());
265
266  if (RetTy->isVoidType()) {
267    // Void type; nothing to return.
268    ReturnValue = 0;
269  } else if (CurFnInfo->getReturnInfo().getKind() == ABIArgInfo::Indirect &&
270             hasAggregateLLVMType(CurFnInfo->getReturnType())) {
271    // Indirect aggregate return; emit returned value directly into sret slot.
272    // This reduces code size, and affects correctness in C++.
273    ReturnValue = CurFn->arg_begin();
274  } else {
275    ReturnValue = CreateIRTemp(RetTy, "retval");
276  }
277
278  EmitStartEHSpec(CurCodeDecl);
279  EmitFunctionProlog(*CurFnInfo, CurFn, Args);
280
281  if (CXXThisDecl)
282    CXXThisValue = Builder.CreateLoad(LocalDeclMap[CXXThisDecl], "this");
283  if (CXXVTTDecl)
284    CXXVTTValue = Builder.CreateLoad(LocalDeclMap[CXXVTTDecl], "vtt");
285
286  // If any of the arguments have a variably modified type, make sure to
287  // emit the type size.
288  for (FunctionArgList::const_iterator i = Args.begin(), e = Args.end();
289       i != e; ++i) {
290    QualType Ty = i->second;
291
292    if (Ty->isVariablyModifiedType())
293      EmitVLASize(Ty);
294  }
295}
296
297void CodeGenFunction::EmitFunctionBody(FunctionArgList &Args) {
298  const FunctionDecl *FD = cast<FunctionDecl>(CurGD.getDecl());
299  assert(FD->getBody());
300  EmitStmt(FD->getBody());
301}
302
303void CodeGenFunction::GenerateCode(GlobalDecl GD, llvm::Function *Fn) {
304  const FunctionDecl *FD = cast<FunctionDecl>(GD.getDecl());
305
306  // Check if we should generate debug info for this function.
307  if (CGM.getDebugInfo() && !FD->hasAttr<NoDebugAttr>())
308    DebugInfo = CGM.getDebugInfo();
309
310  FunctionArgList Args;
311
312  CurGD = GD;
313  if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD)) {
314    if (MD->isInstance()) {
315      // Create the implicit 'this' decl.
316      // FIXME: I'm not entirely sure I like using a fake decl just for code
317      // generation. Maybe we can come up with a better way?
318      CXXThisDecl = ImplicitParamDecl::Create(getContext(), 0,
319                                              FD->getLocation(),
320                                              &getContext().Idents.get("this"),
321                                              MD->getThisType(getContext()));
322      Args.push_back(std::make_pair(CXXThisDecl, CXXThisDecl->getType()));
323
324      // Check if we need a VTT parameter as well.
325      if (CodeGenVTables::needsVTTParameter(GD)) {
326        // FIXME: The comment about using a fake decl above applies here too.
327        QualType T = getContext().getPointerType(getContext().VoidPtrTy);
328        CXXVTTDecl =
329          ImplicitParamDecl::Create(getContext(), 0, FD->getLocation(),
330                                    &getContext().Idents.get("vtt"), T);
331        Args.push_back(std::make_pair(CXXVTTDecl, CXXVTTDecl->getType()));
332      }
333    }
334  }
335
336  if (FD->getNumParams()) {
337    const FunctionProtoType* FProto = FD->getType()->getAs<FunctionProtoType>();
338    assert(FProto && "Function def must have prototype!");
339
340    for (unsigned i = 0, e = FD->getNumParams(); i != e; ++i)
341      Args.push_back(std::make_pair(FD->getParamDecl(i),
342                                    FProto->getArgType(i)));
343  }
344
345  SourceRange BodyRange;
346  if (Stmt *Body = FD->getBody()) BodyRange = Body->getSourceRange();
347
348  // Emit the standard function prologue.
349  StartFunction(GD, FD->getResultType(), Fn, Args, BodyRange.getBegin());
350
351  // Generate the body of the function.
352  if (isa<CXXDestructorDecl>(FD))
353    EmitDestructorBody(Args);
354  else if (isa<CXXConstructorDecl>(FD))
355    EmitConstructorBody(Args);
356  else
357    EmitFunctionBody(Args);
358
359  // Emit the standard function epilogue.
360  FinishFunction(BodyRange.getEnd());
361
362  // Destroy the 'this' declaration.
363  if (CXXThisDecl)
364    CXXThisDecl->Destroy(getContext());
365
366  // Destroy the VTT declaration.
367  if (CXXVTTDecl)
368    CXXVTTDecl->Destroy(getContext());
369}
370
371/// ContainsLabel - Return true if the statement contains a label in it.  If
372/// this statement is not executed normally, it not containing a label means
373/// that we can just remove the code.
374bool CodeGenFunction::ContainsLabel(const Stmt *S, bool IgnoreCaseStmts) {
375  // Null statement, not a label!
376  if (S == 0) return false;
377
378  // If this is a label, we have to emit the code, consider something like:
379  // if (0) {  ...  foo:  bar(); }  goto foo;
380  if (isa<LabelStmt>(S))
381    return true;
382
383  // If this is a case/default statement, and we haven't seen a switch, we have
384  // to emit the code.
385  if (isa<SwitchCase>(S) && !IgnoreCaseStmts)
386    return true;
387
388  // If this is a switch statement, we want to ignore cases below it.
389  if (isa<SwitchStmt>(S))
390    IgnoreCaseStmts = true;
391
392  // Scan subexpressions for verboten labels.
393  for (Stmt::const_child_iterator I = S->child_begin(), E = S->child_end();
394       I != E; ++I)
395    if (ContainsLabel(*I, IgnoreCaseStmts))
396      return true;
397
398  return false;
399}
400
401
402/// ConstantFoldsToSimpleInteger - If the sepcified expression does not fold to
403/// a constant, or if it does but contains a label, return 0.  If it constant
404/// folds to 'true' and does not contain a label, return 1, if it constant folds
405/// to 'false' and does not contain a label, return -1.
406int CodeGenFunction::ConstantFoldsToSimpleInteger(const Expr *Cond) {
407  // FIXME: Rename and handle conversion of other evaluatable things
408  // to bool.
409  Expr::EvalResult Result;
410  if (!Cond->Evaluate(Result, getContext()) || !Result.Val.isInt() ||
411      Result.HasSideEffects)
412    return 0;  // Not foldable, not integer or not fully evaluatable.
413
414  if (CodeGenFunction::ContainsLabel(Cond))
415    return 0;  // Contains a label.
416
417  return Result.Val.getInt().getBoolValue() ? 1 : -1;
418}
419
420
421/// EmitBranchOnBoolExpr - Emit a branch on a boolean condition (e.g. for an if
422/// statement) to the specified blocks.  Based on the condition, this might try
423/// to simplify the codegen of the conditional based on the branch.
424///
425void CodeGenFunction::EmitBranchOnBoolExpr(const Expr *Cond,
426                                           llvm::BasicBlock *TrueBlock,
427                                           llvm::BasicBlock *FalseBlock) {
428  if (const ParenExpr *PE = dyn_cast<ParenExpr>(Cond))
429    return EmitBranchOnBoolExpr(PE->getSubExpr(), TrueBlock, FalseBlock);
430
431  if (const BinaryOperator *CondBOp = dyn_cast<BinaryOperator>(Cond)) {
432    // Handle X && Y in a condition.
433    if (CondBOp->getOpcode() == BinaryOperator::LAnd) {
434      // If we have "1 && X", simplify the code.  "0 && X" would have constant
435      // folded if the case was simple enough.
436      if (ConstantFoldsToSimpleInteger(CondBOp->getLHS()) == 1) {
437        // br(1 && X) -> br(X).
438        return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock);
439      }
440
441      // If we have "X && 1", simplify the code to use an uncond branch.
442      // "X && 0" would have been constant folded to 0.
443      if (ConstantFoldsToSimpleInteger(CondBOp->getRHS()) == 1) {
444        // br(X && 1) -> br(X).
445        return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock);
446      }
447
448      // Emit the LHS as a conditional.  If the LHS conditional is false, we
449      // want to jump to the FalseBlock.
450      llvm::BasicBlock *LHSTrue = createBasicBlock("land.lhs.true");
451      EmitBranchOnBoolExpr(CondBOp->getLHS(), LHSTrue, FalseBlock);
452      EmitBlock(LHSTrue);
453
454      // Any temporaries created here are conditional.
455      BeginConditionalBranch();
456      EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock);
457      EndConditionalBranch();
458
459      return;
460    } else if (CondBOp->getOpcode() == BinaryOperator::LOr) {
461      // If we have "0 || X", simplify the code.  "1 || X" would have constant
462      // folded if the case was simple enough.
463      if (ConstantFoldsToSimpleInteger(CondBOp->getLHS()) == -1) {
464        // br(0 || X) -> br(X).
465        return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock);
466      }
467
468      // If we have "X || 0", simplify the code to use an uncond branch.
469      // "X || 1" would have been constant folded to 1.
470      if (ConstantFoldsToSimpleInteger(CondBOp->getRHS()) == -1) {
471        // br(X || 0) -> br(X).
472        return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock);
473      }
474
475      // Emit the LHS as a conditional.  If the LHS conditional is true, we
476      // want to jump to the TrueBlock.
477      llvm::BasicBlock *LHSFalse = createBasicBlock("lor.lhs.false");
478      EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, LHSFalse);
479      EmitBlock(LHSFalse);
480
481      // Any temporaries created here are conditional.
482      BeginConditionalBranch();
483      EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock);
484      EndConditionalBranch();
485
486      return;
487    }
488  }
489
490  if (const UnaryOperator *CondUOp = dyn_cast<UnaryOperator>(Cond)) {
491    // br(!x, t, f) -> br(x, f, t)
492    if (CondUOp->getOpcode() == UnaryOperator::LNot)
493      return EmitBranchOnBoolExpr(CondUOp->getSubExpr(), FalseBlock, TrueBlock);
494  }
495
496  if (const ConditionalOperator *CondOp = dyn_cast<ConditionalOperator>(Cond)) {
497    // Handle ?: operator.
498
499    // Just ignore GNU ?: extension.
500    if (CondOp->getLHS()) {
501      // br(c ? x : y, t, f) -> br(c, br(x, t, f), br(y, t, f))
502      llvm::BasicBlock *LHSBlock = createBasicBlock("cond.true");
503      llvm::BasicBlock *RHSBlock = createBasicBlock("cond.false");
504      EmitBranchOnBoolExpr(CondOp->getCond(), LHSBlock, RHSBlock);
505      EmitBlock(LHSBlock);
506      EmitBranchOnBoolExpr(CondOp->getLHS(), TrueBlock, FalseBlock);
507      EmitBlock(RHSBlock);
508      EmitBranchOnBoolExpr(CondOp->getRHS(), TrueBlock, FalseBlock);
509      return;
510    }
511  }
512
513  // Emit the code with the fully general case.
514  llvm::Value *CondV = EvaluateExprAsBool(Cond);
515  Builder.CreateCondBr(CondV, TrueBlock, FalseBlock);
516}
517
518/// ErrorUnsupported - Print out an error that codegen doesn't support the
519/// specified stmt yet.
520void CodeGenFunction::ErrorUnsupported(const Stmt *S, const char *Type,
521                                       bool OmitOnError) {
522  CGM.ErrorUnsupported(S, Type, OmitOnError);
523}
524
525void
526CodeGenFunction::EmitNullInitialization(llvm::Value *DestPtr, QualType Ty) {
527  // If the type contains a pointer to data member we can't memset it to zero.
528  // Instead, create a null constant and copy it to the destination.
529  if (CGM.getTypes().ContainsPointerToDataMember(Ty)) {
530    llvm::Constant *NullConstant = CGM.EmitNullConstant(Ty);
531
532    llvm::GlobalVariable *NullVariable =
533      new llvm::GlobalVariable(CGM.getModule(), NullConstant->getType(),
534                               /*isConstant=*/true,
535                               llvm::GlobalVariable::PrivateLinkage,
536                               NullConstant, llvm::Twine());
537    EmitAggregateCopy(DestPtr, NullVariable, Ty, /*isVolatile=*/false);
538    return;
539  }
540
541
542  // Ignore empty classes in C++.
543  if (getContext().getLangOptions().CPlusPlus) {
544    if (const RecordType *RT = Ty->getAs<RecordType>()) {
545      if (cast<CXXRecordDecl>(RT->getDecl())->isEmpty())
546        return;
547    }
548  }
549
550  // Otherwise, just memset the whole thing to zero.  This is legal
551  // because in LLVM, all default initializers (other than the ones we just
552  // handled above) are guaranteed to have a bit pattern of all zeros.
553  const llvm::Type *BP = llvm::Type::getInt8PtrTy(VMContext);
554  if (DestPtr->getType() != BP)
555    DestPtr = Builder.CreateBitCast(DestPtr, BP, "tmp");
556
557  // Get size and alignment info for this aggregate.
558  std::pair<uint64_t, unsigned> TypeInfo = getContext().getTypeInfo(Ty);
559
560  // Don't bother emitting a zero-byte memset.
561  if (TypeInfo.first == 0)
562    return;
563
564  // FIXME: Handle variable sized types.
565  Builder.CreateCall5(CGM.getMemSetFn(BP, IntPtrTy), DestPtr,
566                 llvm::Constant::getNullValue(llvm::Type::getInt8Ty(VMContext)),
567                      // TypeInfo.first describes size in bits.
568                      llvm::ConstantInt::get(IntPtrTy, TypeInfo.first/8),
569                      llvm::ConstantInt::get(Int32Ty, TypeInfo.second/8),
570                      llvm::ConstantInt::get(llvm::Type::getInt1Ty(VMContext),
571                                             0));
572}
573
574llvm::BlockAddress *CodeGenFunction::GetAddrOfLabel(const LabelStmt *L) {
575  // Make sure that there is a block for the indirect goto.
576  if (IndirectBranch == 0)
577    GetIndirectGotoBlock();
578
579  llvm::BasicBlock *BB = getBasicBlockForLabel(L);
580
581  // Make sure the indirect branch includes all of the address-taken blocks.
582  IndirectBranch->addDestination(BB);
583  return llvm::BlockAddress::get(CurFn, BB);
584}
585
586llvm::BasicBlock *CodeGenFunction::GetIndirectGotoBlock() {
587  // If we already made the indirect branch for indirect goto, return its block.
588  if (IndirectBranch) return IndirectBranch->getParent();
589
590  CGBuilderTy TmpBuilder(createBasicBlock("indirectgoto"));
591
592  const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(VMContext);
593
594  // Create the PHI node that indirect gotos will add entries to.
595  llvm::Value *DestVal = TmpBuilder.CreatePHI(Int8PtrTy, "indirect.goto.dest");
596
597  // Create the indirect branch instruction.
598  IndirectBranch = TmpBuilder.CreateIndirectBr(DestVal);
599  return IndirectBranch->getParent();
600}
601
602llvm::Value *CodeGenFunction::GetVLASize(const VariableArrayType *VAT) {
603  llvm::Value *&SizeEntry = VLASizeMap[VAT->getSizeExpr()];
604
605  assert(SizeEntry && "Did not emit size for type");
606  return SizeEntry;
607}
608
609llvm::Value *CodeGenFunction::EmitVLASize(QualType Ty) {
610  assert(Ty->isVariablyModifiedType() &&
611         "Must pass variably modified type to EmitVLASizes!");
612
613  EnsureInsertPoint();
614
615  if (const VariableArrayType *VAT = getContext().getAsVariableArrayType(Ty)) {
616    llvm::Value *&SizeEntry = VLASizeMap[VAT->getSizeExpr()];
617
618    if (!SizeEntry) {
619      const llvm::Type *SizeTy = ConvertType(getContext().getSizeType());
620
621      // Get the element size;
622      QualType ElemTy = VAT->getElementType();
623      llvm::Value *ElemSize;
624      if (ElemTy->isVariableArrayType())
625        ElemSize = EmitVLASize(ElemTy);
626      else
627        ElemSize = llvm::ConstantInt::get(SizeTy,
628            getContext().getTypeSizeInChars(ElemTy).getQuantity());
629
630      llvm::Value *NumElements = EmitScalarExpr(VAT->getSizeExpr());
631      NumElements = Builder.CreateIntCast(NumElements, SizeTy, false, "tmp");
632
633      SizeEntry = Builder.CreateMul(ElemSize, NumElements);
634    }
635
636    return SizeEntry;
637  }
638
639  if (const ArrayType *AT = dyn_cast<ArrayType>(Ty)) {
640    EmitVLASize(AT->getElementType());
641    return 0;
642  }
643
644  const PointerType *PT = Ty->getAs<PointerType>();
645  assert(PT && "unknown VM type!");
646  EmitVLASize(PT->getPointeeType());
647  return 0;
648}
649
650llvm::Value* CodeGenFunction::EmitVAListRef(const Expr* E) {
651  if (CGM.getContext().getBuiltinVaListType()->isArrayType())
652    return EmitScalarExpr(E);
653  return EmitLValue(E).getAddress();
654}
655
656void CodeGenFunction::PushCleanupBlock(llvm::BasicBlock *CleanupEntryBlock,
657                                       llvm::BasicBlock *CleanupExitBlock,
658                                       llvm::BasicBlock *PreviousInvokeDest,
659                                       bool EHOnly) {
660  CleanupEntries.push_back(CleanupEntry(CleanupEntryBlock, CleanupExitBlock,
661                                        PreviousInvokeDest, EHOnly));
662}
663
664void CodeGenFunction::EmitCleanupBlocks(size_t OldCleanupStackSize) {
665  assert(CleanupEntries.size() >= OldCleanupStackSize &&
666         "Cleanup stack mismatch!");
667
668  while (CleanupEntries.size() > OldCleanupStackSize)
669    EmitCleanupBlock();
670}
671
672CodeGenFunction::CleanupBlockInfo CodeGenFunction::PopCleanupBlock() {
673  CleanupEntry &CE = CleanupEntries.back();
674
675  llvm::BasicBlock *CleanupEntryBlock = CE.CleanupEntryBlock;
676
677  std::vector<llvm::BasicBlock *> Blocks;
678  std::swap(Blocks, CE.Blocks);
679
680  std::vector<llvm::BranchInst *> BranchFixups;
681  std::swap(BranchFixups, CE.BranchFixups);
682
683  bool EHOnly = CE.EHOnly;
684
685  setInvokeDest(CE.PreviousInvokeDest);
686
687  CleanupEntries.pop_back();
688
689  // Check if any branch fixups pointed to the scope we just popped. If so,
690  // we can remove them.
691  for (size_t i = 0, e = BranchFixups.size(); i != e; ++i) {
692    llvm::BasicBlock *Dest = BranchFixups[i]->getSuccessor(0);
693    BlockScopeMap::iterator I = BlockScopes.find(Dest);
694
695    if (I == BlockScopes.end())
696      continue;
697
698    assert(I->second <= CleanupEntries.size() && "Invalid branch fixup!");
699
700    if (I->second == CleanupEntries.size()) {
701      // We don't need to do this branch fixup.
702      BranchFixups[i] = BranchFixups.back();
703      BranchFixups.pop_back();
704      i--;
705      e--;
706      continue;
707    }
708  }
709
710  llvm::BasicBlock *SwitchBlock = CE.CleanupExitBlock;
711  llvm::BasicBlock *EndBlock = 0;
712  if (!BranchFixups.empty()) {
713    if (!SwitchBlock)
714      SwitchBlock = createBasicBlock("cleanup.switch");
715    EndBlock = createBasicBlock("cleanup.end");
716
717    llvm::BasicBlock *CurBB = Builder.GetInsertBlock();
718
719    Builder.SetInsertPoint(SwitchBlock);
720
721    llvm::Value *DestCodePtr = CreateTempAlloca(Int32Ty, "cleanup.dst");
722    llvm::Value *DestCode = Builder.CreateLoad(DestCodePtr, "tmp");
723
724    // Create a switch instruction to determine where to jump next.
725    llvm::SwitchInst *SI = Builder.CreateSwitch(DestCode, EndBlock,
726                                                BranchFixups.size());
727
728    // Restore the current basic block (if any)
729    if (CurBB) {
730      Builder.SetInsertPoint(CurBB);
731
732      // If we had a current basic block, we also need to emit an instruction
733      // to initialize the cleanup destination.
734      Builder.CreateStore(llvm::Constant::getNullValue(Int32Ty),
735                          DestCodePtr);
736    } else
737      Builder.ClearInsertionPoint();
738
739    for (size_t i = 0, e = BranchFixups.size(); i != e; ++i) {
740      llvm::BranchInst *BI = BranchFixups[i];
741      llvm::BasicBlock *Dest = BI->getSuccessor(0);
742
743      // Fixup the branch instruction to point to the cleanup block.
744      BI->setSuccessor(0, CleanupEntryBlock);
745
746      if (CleanupEntries.empty()) {
747        llvm::ConstantInt *ID;
748
749        // Check if we already have a destination for this block.
750        if (Dest == SI->getDefaultDest())
751          ID = llvm::ConstantInt::get(Int32Ty, 0);
752        else {
753          ID = SI->findCaseDest(Dest);
754          if (!ID) {
755            // No code found, get a new unique one by using the number of
756            // switch successors.
757            ID = llvm::ConstantInt::get(Int32Ty, SI->getNumSuccessors());
758            SI->addCase(ID, Dest);
759          }
760        }
761
762        // Store the jump destination before the branch instruction.
763        new llvm::StoreInst(ID, DestCodePtr, BI);
764      } else {
765        // We need to jump through another cleanup block. Create a pad block
766        // with a branch instruction that jumps to the final destination and add
767        // it as a branch fixup to the current cleanup scope.
768
769        // Create the pad block.
770        llvm::BasicBlock *CleanupPad = createBasicBlock("cleanup.pad", CurFn);
771
772        // Create a unique case ID.
773        llvm::ConstantInt *ID
774          = llvm::ConstantInt::get(Int32Ty, SI->getNumSuccessors());
775
776        // Store the jump destination before the branch instruction.
777        new llvm::StoreInst(ID, DestCodePtr, BI);
778
779        // Add it as the destination.
780        SI->addCase(ID, CleanupPad);
781
782        // Create the branch to the final destination.
783        llvm::BranchInst *BI = llvm::BranchInst::Create(Dest);
784        CleanupPad->getInstList().push_back(BI);
785
786        // And add it as a branch fixup.
787        CleanupEntries.back().BranchFixups.push_back(BI);
788      }
789    }
790  }
791
792  // Remove all blocks from the block scope map.
793  for (size_t i = 0, e = Blocks.size(); i != e; ++i) {
794    assert(BlockScopes.count(Blocks[i]) &&
795           "Did not find block in scope map!");
796
797    BlockScopes.erase(Blocks[i]);
798  }
799
800  return CleanupBlockInfo(CleanupEntryBlock, SwitchBlock, EndBlock, EHOnly);
801}
802
803void CodeGenFunction::EmitCleanupBlock() {
804  CleanupBlockInfo Info = PopCleanupBlock();
805
806  if (Info.EHOnly) {
807    // FIXME: Add this to the exceptional edge
808    if (Info.CleanupBlock->getNumUses() == 0)
809      delete Info.CleanupBlock;
810    return;
811  }
812
813  //  Scrub debug location info.
814  for (llvm::BasicBlock::iterator LBI = Info.CleanupBlock->begin(),
815         LBE = Info.CleanupBlock->end(); LBI != LBE; ++LBI)
816    Builder.SetInstDebugLocation(LBI);
817
818  llvm::BasicBlock *CurBB = Builder.GetInsertBlock();
819  if (CurBB && !CurBB->getTerminator() &&
820      Info.CleanupBlock->getNumUses() == 0) {
821    CurBB->getInstList().splice(CurBB->end(), Info.CleanupBlock->getInstList());
822    delete Info.CleanupBlock;
823  } else
824    EmitBlock(Info.CleanupBlock);
825
826  if (Info.SwitchBlock)
827    EmitBlock(Info.SwitchBlock);
828  if (Info.EndBlock)
829    EmitBlock(Info.EndBlock);
830}
831
832void CodeGenFunction::AddBranchFixup(llvm::BranchInst *BI) {
833  assert(!CleanupEntries.empty() &&
834         "Trying to add branch fixup without cleanup block!");
835
836  // FIXME: We could be more clever here and check if there's already a branch
837  // fixup for this destination and recycle it.
838  CleanupEntries.back().BranchFixups.push_back(BI);
839}
840
841void CodeGenFunction::EmitBranchThroughCleanup(llvm::BasicBlock *Dest) {
842  if (!HaveInsertPoint())
843    return;
844
845  llvm::BranchInst* BI = Builder.CreateBr(Dest);
846
847  Builder.ClearInsertionPoint();
848
849  // The stack is empty, no need to do any cleanup.
850  if (CleanupEntries.empty())
851    return;
852
853  if (!Dest->getParent()) {
854    // We are trying to branch to a block that hasn't been inserted yet.
855    AddBranchFixup(BI);
856    return;
857  }
858
859  BlockScopeMap::iterator I = BlockScopes.find(Dest);
860  if (I == BlockScopes.end()) {
861    // We are trying to jump to a block that is outside of any cleanup scope.
862    AddBranchFixup(BI);
863    return;
864  }
865
866  assert(I->second < CleanupEntries.size() &&
867         "Trying to branch into cleanup region");
868
869  if (I->second == CleanupEntries.size() - 1) {
870    // We have a branch to a block in the same scope.
871    return;
872  }
873
874  AddBranchFixup(BI);
875}
876