Merge branch 'master' of ssh://bitbucket.org/czan/honours

1 files changed, 464 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/CGDeclCXX.cpp b/clang/lib/CodeGen/CGDeclCXX.cpp
new file mode 100644
index 0000000..10f0b83
--- /dev/null
+++ b/clang/lib/CodeGen/CGDeclCXX.cpp
@@ -0,0 +1,464 @@
+//===--- CGDeclCXX.cpp - Emit LLVM Code for C++ declarations --------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This contains code dealing with code generation of C++ declarations
+//
+//===----------------------------------------------------------------------===//
+
+#include "CodeGenFunction.h"
+#include "CGObjCRuntime.h"
+#include "CGCXXABI.h"
+#include "clang/Frontend/CodeGenOptions.h"
+#include "llvm/Intrinsics.h"
+
+using namespace clang;
+using namespace CodeGen;
+
+static void EmitDeclInit(CodeGenFunction &CGF, const VarDecl &D,
+                         llvm::Constant *DeclPtr) {
+  assert(D.hasGlobalStorage() && "VarDecl must have global storage!");
+  assert(!D.getType()->isReferenceType() && 
+         "Should not call EmitDeclInit on a reference!");
+  
+  ASTContext &Context = CGF.getContext();
+
+  CharUnits alignment = Context.getDeclAlign(&D);
+  QualType type = D.getType();
+  LValue lv = CGF.MakeAddrLValue(DeclPtr, type, alignment);
+
+  const Expr *Init = D.getInit();
+  if (!CGF.hasAggregateLLVMType(type)) {
+    CodeGenModule &CGM = CGF.CGM;
+    if (lv.isObjCStrong())
+      CGM.getObjCRuntime().EmitObjCGlobalAssign(CGF, CGF.EmitScalarExpr(Init),
+                                                DeclPtr, D.isThreadSpecified());
+    else if (lv.isObjCWeak())
+      CGM.getObjCRuntime().EmitObjCWeakAssign(CGF, CGF.EmitScalarExpr(Init),
+                                              DeclPtr);
+    else
+      CGF.EmitScalarInit(Init, &D, lv, false);
+  } else if (type->isAnyComplexType()) {
+    CGF.EmitComplexExprIntoAddr(Init, DeclPtr, lv.isVolatile());
+  } else {
+    CGF.EmitAggExpr(Init, AggValueSlot::forLValue(lv,AggValueSlot::IsDestructed,
+                                          AggValueSlot::DoesNotNeedGCBarriers,
+                                                  AggValueSlot::IsNotAliased));
+  }
+}
+
+/// Emit code to cause the destruction of the given variable with
+/// static storage duration.
+static void EmitDeclDestroy(CodeGenFunction &CGF, const VarDecl &D,
+                            llvm::Constant *addr) {
+  CodeGenModule &CGM = CGF.CGM;
+
+  // FIXME:  __attribute__((cleanup)) ?
+  
+  QualType type = D.getType();
+  QualType::DestructionKind dtorKind = type.isDestructedType();
+
+  switch (dtorKind) {
+  case QualType::DK_none:
+    return;
+
+  case QualType::DK_cxx_destructor:
+    break;
+
+  case QualType::DK_objc_strong_lifetime:
+  case QualType::DK_objc_weak_lifetime:
+    // We don't care about releasing objects during process teardown.
+    return;
+  }
+
+  llvm::Constant *function;
+  llvm::Constant *argument;
+
+  // Special-case non-array C++ destructors, where there's a function
+  // with the right signature that we can just call.
+  const CXXRecordDecl *record = 0;
+  if (dtorKind == QualType::DK_cxx_destructor &&
+      (record = type->getAsCXXRecordDecl())) {
+    assert(!record->hasTrivialDestructor());
+    CXXDestructorDecl *dtor = record->getDestructor();
+
+    function = CGM.GetAddrOfCXXDestructor(dtor, Dtor_Complete);
+    argument = addr;
+
+  // Otherwise, the standard logic requires a helper function.
+  } else {
+    function = CodeGenFunction(CGM).generateDestroyHelper(addr, type,
+                                                  CGF.getDestroyer(dtorKind),
+                                                  CGF.needsEHCleanup(dtorKind));
+    argument = llvm::Constant::getNullValue(CGF.Int8PtrTy);
+  }
+
+  CGF.EmitCXXGlobalDtorRegistration(function, argument);
+}
+
+/// Emit code to cause the variable at the given address to be considered as
+/// constant from this point onwards.
+static void EmitDeclInvariant(CodeGenFunction &CGF, const VarDecl &D,
+                              llvm::Constant *Addr) {
+  // Don't emit the intrinsic if we're not optimizing.
+  if (!CGF.CGM.getCodeGenOpts().OptimizationLevel)
+    return;
+
+  // Grab the llvm.invariant.start intrinsic.
+  llvm::Intrinsic::ID InvStartID = llvm::Intrinsic::invariant_start;
+  llvm::Constant *InvariantStart = CGF.CGM.getIntrinsic(InvStartID);
+
+  // Emit a call with the size in bytes of the object.
+  CharUnits WidthChars = CGF.getContext().getTypeSizeInChars(D.getType());
+  uint64_t Width = WidthChars.getQuantity();
+  llvm::Value *Args[2] = { llvm::ConstantInt::getSigned(CGF.Int64Ty, Width),
+                           llvm::ConstantExpr::getBitCast(Addr, CGF.Int8PtrTy)};
+  CGF.Builder.CreateCall(InvariantStart, Args);
+}
+
+void CodeGenFunction::EmitCXXGlobalVarDeclInit(const VarDecl &D,
+                                               llvm::Constant *DeclPtr,
+                                               bool PerformInit) {
+
+  const Expr *Init = D.getInit();
+  QualType T = D.getType();
+
+  if (!T->isReferenceType()) {
+    if (PerformInit)
+      EmitDeclInit(*this, D, DeclPtr);
+    if (CGM.isTypeConstant(D.getType(), true))
+      EmitDeclInvariant(*this, D, DeclPtr);
+    else
+      EmitDeclDestroy(*this, D, DeclPtr);
+    return;
+  }
+
+  assert(PerformInit && "cannot have constant initializer which needs "
+         "destruction for reference");
+  unsigned Alignment = getContext().getDeclAlign(&D).getQuantity();
+  RValue RV = EmitReferenceBindingToExpr(Init, &D);
+  EmitStoreOfScalar(RV.getScalarVal(), DeclPtr, false, Alignment, T);
+}
+
+/// Register a global destructor using __cxa_atexit.
+static void emitGlobalDtorWithCXAAtExit(CodeGenFunction &CGF,
+                                        llvm::Constant *dtor,
+                                        llvm::Constant *addr) {
+  // We're assuming that the destructor function is something we can
+  // reasonably call with the default CC.  Go ahead and cast it to the
+  // right prototype.
+  llvm::Type *dtorTy =
+    llvm::FunctionType::get(CGF.VoidTy, CGF.Int8PtrTy, false)->getPointerTo();
+
+  // extern "C" int __cxa_atexit(void (*f)(void *), void *p, void *d);
+  llvm::Type *paramTys[] = { dtorTy, CGF.Int8PtrTy, CGF.Int8PtrTy };
+  llvm::FunctionType *atexitTy =
+    llvm::FunctionType::get(CGF.IntTy, paramTys, false);
+
+  // Fetch the actual function.
+  llvm::Constant *atexit =
+    CGF.CGM.CreateRuntimeFunction(atexitTy, "__cxa_atexit");
+  if (llvm::Function *fn = dyn_cast<llvm::Function>(atexit))
+    fn->setDoesNotThrow();
+
+  // Create a variable that binds the atexit to this shared object.
+  llvm::Constant *handle =
+    CGF.CGM.CreateRuntimeVariable(CGF.Int8Ty, "__dso_handle");
+
+  llvm::Value *args[] = {
+    llvm::ConstantExpr::getBitCast(dtor, dtorTy),
+    llvm::ConstantExpr::getBitCast(addr, CGF.Int8PtrTy),
+    handle
+  };
+  CGF.Builder.CreateCall(atexit, args);
+}
+
+static llvm::Function *
+CreateGlobalInitOrDestructFunction(CodeGenModule &CGM,
+                                   llvm::FunctionType *ty,
+                                   const Twine &name);
+
+/// Create a stub function, suitable for being passed to atexit,
+/// which passes the given address to the given destructor function.
+static llvm::Constant *createAtExitStub(CodeGenModule &CGM,
+                                        llvm::Constant *dtor,
+                                        llvm::Constant *addr) {
+  // Get the destructor function type, void(*)(void).
+  llvm::FunctionType *ty = llvm::FunctionType::get(CGM.VoidTy, false);
+  llvm::Function *fn =
+    CreateGlobalInitOrDestructFunction(CGM, ty,
+                                       Twine("__dtor_", addr->getName()));
+
+  CodeGenFunction CGF(CGM);
+
+  CGF.StartFunction(GlobalDecl(), CGM.getContext().VoidTy, fn,
+                    CGM.getTypes().arrangeNullaryFunction(),
+                    FunctionArgList(), SourceLocation());
+
+  llvm::CallInst *call = CGF.Builder.CreateCall(dtor, addr);
+ 
+ // Make sure the call and the callee agree on calling convention.
+  if (llvm::Function *dtorFn =
+        dyn_cast<llvm::Function>(dtor->stripPointerCasts()))
+    call->setCallingConv(dtorFn->getCallingConv());
+
+  CGF.FinishFunction();
+
+  return fn;
+}
+
+/// Register a global destructor using atexit.
+static void emitGlobalDtorWithAtExit(CodeGenFunction &CGF,
+                                     llvm::Constant *dtor,
+                                     llvm::Constant *addr) {
+  // Create a function which calls the destructor.
+  llvm::Constant *dtorStub = createAtExitStub(CGF.CGM, dtor, addr);
+
+  // extern "C" int atexit(void (*f)(void));
+  llvm::FunctionType *atexitTy =
+    llvm::FunctionType::get(CGF.IntTy, dtorStub->getType(), false);
+
+  llvm::Constant *atexit =
+    CGF.CGM.CreateRuntimeFunction(atexitTy, "atexit");
+  if (llvm::Function *atexitFn = dyn_cast<llvm::Function>(atexit))
+    atexitFn->setDoesNotThrow();
+
+  CGF.Builder.CreateCall(atexit, dtorStub);
+}
+
+void CodeGenFunction::EmitCXXGlobalDtorRegistration(llvm::Constant *dtor,
+                                                    llvm::Constant *addr) {
+  // Use __cxa_atexit if available.
+  if (CGM.getCodeGenOpts().CXAAtExit) {
+    emitGlobalDtorWithCXAAtExit(*this, dtor, addr);
+    return;
+  }
+
+  // In Apple kexts, we want to add a global destructor entry.
+  // FIXME: shouldn't this be guarded by some variable?
+  if (CGM.getContext().getLangOpts().AppleKext) {
+    // Generate a global destructor entry.
+    CGM.AddCXXDtorEntry(dtor, addr);
+    return;
+  }
+
+  // Otherwise, we just use atexit.
+  emitGlobalDtorWithAtExit(*this, dtor, addr);
+}
+
+void CodeGenFunction::EmitCXXGuardedInit(const VarDecl &D,
+                                         llvm::GlobalVariable *DeclPtr,
+                                         bool PerformInit) {
+  // If we've been asked to forbid guard variables, emit an error now.
+  // This diagnostic is hard-coded for Darwin's use case;  we can find
+  // better phrasing if someone else needs it.
+  if (CGM.getCodeGenOpts().ForbidGuardVariables)
+    CGM.Error(D.getLocation(),
+              "this initialization requires a guard variable, which "
+              "the kernel does not support");
+
+  CGM.getCXXABI().EmitGuardedInit(*this, D, DeclPtr, PerformInit);
+}
+
+static llvm::Function *
+CreateGlobalInitOrDestructFunction(CodeGenModule &CGM,
+                                   llvm::FunctionType *FTy,
+                                   const Twine &Name) {
+  llvm::Function *Fn =
+    llvm::Function::Create(FTy, llvm::GlobalValue::InternalLinkage,
+                           Name, &CGM.getModule());
+  if (!CGM.getContext().getLangOpts().AppleKext) {
+    // Set the section if needed.
+    if (const char *Section = 
+          CGM.getContext().getTargetInfo().getStaticInitSectionSpecifier())
+      Fn->setSection(Section);
+  }
+
+  if (!CGM.getLangOpts().Exceptions)
+    Fn->setDoesNotThrow();
+
+  return Fn;
+}
+
+void
+CodeGenModule::EmitCXXGlobalVarDeclInitFunc(const VarDecl *D,
+                                            llvm::GlobalVariable *Addr,
+                                            bool PerformInit) {
+  llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false);
+
+  // Create a variable initialization function.
+  llvm::Function *Fn =
+    CreateGlobalInitOrDestructFunction(*this, FTy, "__cxx_global_var_init");
+
+  CodeGenFunction(*this).GenerateCXXGlobalVarDeclInitFunc(Fn, D, Addr,
+                                                          PerformInit);
+
+  if (D->hasAttr<InitPriorityAttr>()) {
+    unsigned int order = D->getAttr<InitPriorityAttr>()->getPriority();
+    OrderGlobalInits Key(order, PrioritizedCXXGlobalInits.size());
+    PrioritizedCXXGlobalInits.push_back(std::make_pair(Key, Fn));
+    DelayedCXXInitPosition.erase(D);
+  }
+  else {
+    llvm::DenseMap<const Decl *, unsigned>::iterator I =
+      DelayedCXXInitPosition.find(D);
+    if (I == DelayedCXXInitPosition.end()) {
+      CXXGlobalInits.push_back(Fn);
+    } else {
+      assert(CXXGlobalInits[I->second] == 0);
+      CXXGlobalInits[I->second] = Fn;
+      DelayedCXXInitPosition.erase(I);
+    }
+  }
+}
+
+void
+CodeGenModule::EmitCXXGlobalInitFunc() {
+  while (!CXXGlobalInits.empty() && !CXXGlobalInits.back())
+    CXXGlobalInits.pop_back();
+
+  if (CXXGlobalInits.empty() && PrioritizedCXXGlobalInits.empty())
+    return;
+
+  llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false);
+
+  // Create our global initialization function.
+  llvm::Function *Fn = 
+    CreateGlobalInitOrDestructFunction(*this, FTy, "_GLOBAL__I_a");
+
+  if (!PrioritizedCXXGlobalInits.empty()) {
+    SmallVector<llvm::Constant*, 8> LocalCXXGlobalInits;
+    llvm::array_pod_sort(PrioritizedCXXGlobalInits.begin(), 
+                         PrioritizedCXXGlobalInits.end()); 
+    for (unsigned i = 0; i < PrioritizedCXXGlobalInits.size(); i++) {
+      llvm::Function *Fn = PrioritizedCXXGlobalInits[i].second;
+      LocalCXXGlobalInits.push_back(Fn);
+    }
+    LocalCXXGlobalInits.append(CXXGlobalInits.begin(), CXXGlobalInits.end());
+    CodeGenFunction(*this).GenerateCXXGlobalInitFunc(Fn,
+                                                    &LocalCXXGlobalInits[0],
+                                                    LocalCXXGlobalInits.size());
+  }
+  else
+    CodeGenFunction(*this).GenerateCXXGlobalInitFunc(Fn,
+                                                     &CXXGlobalInits[0],
+                                                     CXXGlobalInits.size());
+  AddGlobalCtor(Fn);
+  CXXGlobalInits.clear();
+  PrioritizedCXXGlobalInits.clear();
+}
+
+void CodeGenModule::EmitCXXGlobalDtorFunc() {
+  if (CXXGlobalDtors.empty())
+    return;
+
+  llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false);
+
+  // Create our global destructor function.
+  llvm::Function *Fn =
+    CreateGlobalInitOrDestructFunction(*this, FTy, "_GLOBAL__D_a");
+
+  CodeGenFunction(*this).GenerateCXXGlobalDtorsFunc(Fn, CXXGlobalDtors);
+  AddGlobalDtor(Fn);
+}
+
+/// Emit the code necessary to initialize the given global variable.
+void CodeGenFunction::GenerateCXXGlobalVarDeclInitFunc(llvm::Function *Fn,
+                                                       const VarDecl *D,
+                                                 llvm::GlobalVariable *Addr,
+                                                       bool PerformInit) {
+  StartFunction(GlobalDecl(), getContext().VoidTy, Fn,
+                getTypes().arrangeNullaryFunction(),
+                FunctionArgList(), SourceLocation());
+
+  // Use guarded initialization if the global variable is weak. This
+  // occurs for, e.g., instantiated static data members and
+  // definitions explicitly marked weak.
+  if (Addr->getLinkage() == llvm::GlobalValue::WeakODRLinkage ||
+      Addr->getLinkage() == llvm::GlobalValue::WeakAnyLinkage) {
+    EmitCXXGuardedInit(*D, Addr, PerformInit);
+  } else {
+    EmitCXXGlobalVarDeclInit(*D, Addr, PerformInit);
+  }
+
+  FinishFunction();
+}
+
+void CodeGenFunction::GenerateCXXGlobalInitFunc(llvm::Function *Fn,
+                                                llvm::Constant **Decls,
+                                                unsigned NumDecls) {
+  StartFunction(GlobalDecl(), getContext().VoidTy, Fn,
+                getTypes().arrangeNullaryFunction(),
+                FunctionArgList(), SourceLocation());
+
+  RunCleanupsScope Scope(*this);
+
+  // When building in Objective-C++ ARC mode, create an autorelease pool
+  // around the global initializers.
+  if (getLangOpts().ObjCAutoRefCount && getLangOpts().CPlusPlus) {    
+    llvm::Value *token = EmitObjCAutoreleasePoolPush();
+    EmitObjCAutoreleasePoolCleanup(token);
+  }
+  
+  for (unsigned i = 0; i != NumDecls; ++i)
+    if (Decls[i])
+      Builder.CreateCall(Decls[i]);    
+
+  Scope.ForceCleanup();
+  
+  FinishFunction();
+}
+
+void CodeGenFunction::GenerateCXXGlobalDtorsFunc(llvm::Function *Fn,
+                  const std::vector<std::pair<llvm::WeakVH, llvm::Constant*> >
+                                                &DtorsAndObjects) {
+  StartFunction(GlobalDecl(), getContext().VoidTy, Fn,
+                getTypes().arrangeNullaryFunction(),
+                FunctionArgList(), SourceLocation());
+
+  // Emit the dtors, in reverse order from construction.
+  for (unsigned i = 0, e = DtorsAndObjects.size(); i != e; ++i) {
+    llvm::Value *Callee = DtorsAndObjects[e - i - 1].first;
+    llvm::CallInst *CI = Builder.CreateCall(Callee,
+                                            DtorsAndObjects[e - i - 1].second);
+    // Make sure the call and the callee agree on calling convention.
+    if (llvm::Function *F = dyn_cast<llvm::Function>(Callee))
+      CI->setCallingConv(F->getCallingConv());
+  }
+
+  FinishFunction();
+}
+
+/// generateDestroyHelper - Generates a helper function which, when
+/// invoked, destroys the given object.
+llvm::Function * 
+CodeGenFunction::generateDestroyHelper(llvm::Constant *addr,
+                                       QualType type,
+                                       Destroyer *destroyer,
+                                       bool useEHCleanupForArray) {
+  FunctionArgList args;
+  ImplicitParamDecl dst(0, SourceLocation(), 0, getContext().VoidPtrTy);
+  args.push_back(&dst);
+  
+  const CGFunctionInfo &FI = 
+    CGM.getTypes().arrangeFunctionDeclaration(getContext().VoidTy, args,
+                                              FunctionType::ExtInfo(),
+                                              /*variadic*/ false);
+  llvm::FunctionType *FTy = CGM.getTypes().GetFunctionType(FI);
+  llvm::Function *fn = 
+    CreateGlobalInitOrDestructFunction(CGM, FTy, "__cxx_global_array_dtor");
+
+  StartFunction(GlobalDecl(), getContext().VoidTy, fn, FI, args,
+                SourceLocation());
+
+  emitDestroy(addr, type, destroyer, useEHCleanupForArray);
+  
+  FinishFunction();
+  
+  return fn;
+}