1 files changed, 312 insertions, 0 deletions
diff --git a/contrib/llvm/tools/clang/lib/CodeGen/CodeGenTBAA.cpp b/contrib/llvm/tools/clang/lib/CodeGen/CodeGenTBAA.cpp
new file mode 100644
index 0000000..7e4d34a
--- /dev/null
+++ b/contrib/llvm/tools/clang/lib/CodeGen/CodeGenTBAA.cpp
@@ -0,0 +1,312 @@
+//===--- CodeGenTypes.cpp - TBAA information for LLVM CodeGen -------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This is the code that manages TBAA information and defines the TBAA policy
+// for the optimizer to use. Relevant standards text includes:
+//
+//   C99 6.5p7
+//   C++ [basic.lval] (p10 in n3126, p15 in some earlier versions)
+//
+//===----------------------------------------------------------------------===//
+
+#include "CodeGenTBAA.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/Attr.h"
+#include "clang/AST/Mangle.h"
+#include "clang/AST/RecordLayout.h"
+#include "clang/Frontend/CodeGenOptions.h"
+#include "llvm/ADT/SmallSet.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Metadata.h"
+#include "llvm/IR/Type.h"
+using namespace clang;
+using namespace CodeGen;
+
+CodeGenTBAA::CodeGenTBAA(ASTContext &Ctx, llvm::LLVMContext& VMContext,
+                         const CodeGenOptions &CGO,
+                         const LangOptions &Features, MangleContext &MContext)
+  : Context(Ctx), CodeGenOpts(CGO), Features(Features), MContext(MContext),
+    MDHelper(VMContext), Root(0), Char(0) {
+}
+
+CodeGenTBAA::~CodeGenTBAA() {
+}
+
+llvm::MDNode *CodeGenTBAA::getRoot() {
+  // Define the root of the tree. This identifies the tree, so that
+  // if our LLVM IR is linked with LLVM IR from a different front-end
+  // (or a different version of this front-end), their TBAA trees will
+  // remain distinct, and the optimizer will treat them conservatively.
+  if (!Root)
+    Root = MDHelper.createTBAARoot("Simple C/C++ TBAA");
+
+  return Root;
+}
+
+llvm::MDNode *CodeGenTBAA::getChar() {
+  // Define the root of the tree for user-accessible memory. C and C++
+  // give special powers to char and certain similar types. However,
+  // these special powers only cover user-accessible memory, and doesn't
+  // include things like vtables.
+  if (!Char)
+    Char = MDHelper.createTBAANode("omnipotent char", getRoot());
+
+  return Char;
+}
+
+static bool TypeHasMayAlias(QualType QTy) {
+  // Tagged types have declarations, and therefore may have attributes.
+  if (const TagType *TTy = dyn_cast<TagType>(QTy))
+    return TTy->getDecl()->hasAttr<MayAliasAttr>();
+
+  // Typedef types have declarations, and therefore may have attributes.
+  if (const TypedefType *TTy = dyn_cast<TypedefType>(QTy)) {
+    if (TTy->getDecl()->hasAttr<MayAliasAttr>())
+      return true;
+    // Also, their underlying types may have relevant attributes.
+    return TypeHasMayAlias(TTy->desugar());
+  }
+
+  return false;
+}
+
+llvm::MDNode *
+CodeGenTBAA::getTBAAInfo(QualType QTy) {
+  // At -O0 TBAA is not emitted for regular types.
+  if (CodeGenOpts.OptimizationLevel == 0 || CodeGenOpts.RelaxedAliasing)
+    return NULL;
+
+  // If the type has the may_alias attribute (even on a typedef), it is
+  // effectively in the general char alias class.
+  if (TypeHasMayAlias(QTy))
+    return getChar();
+
+  const Type *Ty = Context.getCanonicalType(QTy).getTypePtr();
+
+  if (llvm::MDNode *N = MetadataCache[Ty])
+    return N;
+
+  // Handle builtin types.
+  if (const BuiltinType *BTy = dyn_cast<BuiltinType>(Ty)) {
+    switch (BTy->getKind()) {
+    // Character types are special and can alias anything.
+    // In C++, this technically only includes "char" and "unsigned char",
+    // and not "signed char". In C, it includes all three. For now,
+    // the risk of exploiting this detail in C++ seems likely to outweigh
+    // the benefit.
+    case BuiltinType::Char_U:
+    case BuiltinType::Char_S:
+    case BuiltinType::UChar:
+    case BuiltinType::SChar:
+      return getChar();
+
+    // Unsigned types can alias their corresponding signed types.
+    case BuiltinType::UShort:
+      return getTBAAInfo(Context.ShortTy);
+    case BuiltinType::UInt:
+      return getTBAAInfo(Context.IntTy);
+    case BuiltinType::ULong:
+      return getTBAAInfo(Context.LongTy);
+    case BuiltinType::ULongLong:
+      return getTBAAInfo(Context.LongLongTy);
+    case BuiltinType::UInt128:
+      return getTBAAInfo(Context.Int128Ty);
+
+    // Treat all other builtin types as distinct types. This includes
+    // treating wchar_t, char16_t, and char32_t as distinct from their
+    // "underlying types".
+    default:
+      return MetadataCache[Ty] =
+        MDHelper.createTBAANode(BTy->getName(Features), getChar());
+    }
+  }
+
+  // Handle pointers.
+  // TODO: Implement C++'s type "similarity" and consider dis-"similar"
+  // pointers distinct.
+  if (Ty->isPointerType())
+    return MetadataCache[Ty] = MDHelper.createTBAANode("any pointer",
+                                                       getChar());
+
+  // Enum types are distinct types. In C++ they have "underlying types",
+  // however they aren't related for TBAA.
+  if (const EnumType *ETy = dyn_cast<EnumType>(Ty)) {
+    // In C mode, two anonymous enums are compatible iff their members
+    // are the same -- see C99 6.2.7p1. For now, be conservative. We could
+    // theoretically implement this by combining information about all the
+    // members into a single identifying MDNode.
+    if (!Features.CPlusPlus &&
+        ETy->getDecl()->getTypedefNameForAnonDecl())
+      return MetadataCache[Ty] = getChar();
+
+    // In C++ mode, types have linkage, so we can rely on the ODR and
+    // on their mangled names, if they're external.
+    // TODO: Is there a way to get a program-wide unique name for a
+    // decl with local linkage or no linkage?
+    if (Features.CPlusPlus &&
+        ETy->getDecl()->getLinkage() != ExternalLinkage)
+      return MetadataCache[Ty] = getChar();
+
+    // TODO: This is using the RTTI name. Is there a better way to get
+    // a unique string for a type?
+    SmallString<256> OutName;
+    llvm::raw_svector_ostream Out(OutName);
+    MContext.mangleCXXRTTIName(QualType(ETy, 0), Out);
+    Out.flush();
+    return MetadataCache[Ty] = MDHelper.createTBAANode(OutName, getChar());
+  }
+
+  // For now, handle any other kind of type conservatively.
+  return MetadataCache[Ty] = getChar();
+}
+
+llvm::MDNode *CodeGenTBAA::getTBAAInfoForVTablePtr() {
+  return MDHelper.createTBAANode("vtable pointer", getRoot());
+}
+
+bool
+CodeGenTBAA::CollectFields(uint64_t BaseOffset,
+                           QualType QTy,
+                           SmallVectorImpl<llvm::MDBuilder::TBAAStructField> &
+                             Fields,
+                           bool MayAlias) {
+  /* Things not handled yet include: C++ base classes, bitfields, */
+
+  if (const RecordType *TTy = QTy->getAs<RecordType>()) {
+    const RecordDecl *RD = TTy->getDecl()->getDefinition();
+    if (RD->hasFlexibleArrayMember())
+      return false;
+
+    // TODO: Handle C++ base classes.
+    if (const CXXRecordDecl *Decl = dyn_cast<CXXRecordDecl>(RD))
+      if (Decl->bases_begin() != Decl->bases_end())
+        return false;
+
+    const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
+
+    unsigned idx = 0;
+    for (RecordDecl::field_iterator i = RD->field_begin(),
+         e = RD->field_end(); i != e; ++i, ++idx) {
+      uint64_t Offset = BaseOffset +
+                        Layout.getFieldOffset(idx) / Context.getCharWidth();
+      QualType FieldQTy = i->getType();
+      if (!CollectFields(Offset, FieldQTy, Fields,
+                         MayAlias || TypeHasMayAlias(FieldQTy)))
+        return false;
+    }
+    return true;
+  }
+
+  /* Otherwise, treat whatever it is as a field. */
+  uint64_t Offset = BaseOffset;
+  uint64_t Size = Context.getTypeSizeInChars(QTy).getQuantity();
+  llvm::MDNode *TBAAInfo = MayAlias ? getChar() : getTBAAInfo(QTy);
+  Fields.push_back(llvm::MDBuilder::TBAAStructField(Offset, Size, TBAAInfo));
+  return true;
+}
+
+llvm::MDNode *
+CodeGenTBAA::getTBAAStructInfo(QualType QTy) {
+  const Type *Ty = Context.getCanonicalType(QTy).getTypePtr();
+
+  if (llvm::MDNode *N = StructMetadataCache[Ty])
+    return N;
+
+  SmallVector<llvm::MDBuilder::TBAAStructField, 4> Fields;
+  if (CollectFields(0, QTy, Fields, TypeHasMayAlias(QTy)))
+    return MDHelper.createTBAAStructNode(Fields);
+
+  // For now, handle any other kind of type conservatively.
+  return StructMetadataCache[Ty] = NULL;
+}
+
+/// Check if the given type can be handled by path-aware TBAA.
+static bool isTBAAPathStruct(QualType QTy) {
+  if (const RecordType *TTy = QTy->getAs<RecordType>()) {
+    const RecordDecl *RD = TTy->getDecl()->getDefinition();
+    // RD can be struct, union, class, interface or enum.
+    // For now, we only handle struct.
+    if (RD->isStruct() && !RD->hasFlexibleArrayMember())
+      return true;
+  }
+  return false;
+}
+
+llvm::MDNode *
+CodeGenTBAA::getTBAAStructTypeInfo(QualType QTy) {
+  const Type *Ty = Context.getCanonicalType(QTy).getTypePtr();
+  assert(isTBAAPathStruct(QTy));
+
+  if (llvm::MDNode *N = StructTypeMetadataCache[Ty])
+    return N;
+
+  if (const RecordType *TTy = QTy->getAs<RecordType>()) {
+    const RecordDecl *RD = TTy->getDecl()->getDefinition();
+
+    const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
+    SmallVector <std::pair<uint64_t, llvm::MDNode*>, 4> Fields;
+    // To reduce the size of MDNode for a given struct type, we only output
+    // once for all the fields with the same scalar types.
+    // Offsets for scalar fields in the type DAG are not used.
+    llvm::SmallSet <llvm::MDNode*, 4> ScalarFieldTypes;
+    unsigned idx = 0;
+    for (RecordDecl::field_iterator i = RD->field_begin(),
+         e = RD->field_end(); i != e; ++i, ++idx) {
+      QualType FieldQTy = i->getType();
+      llvm::MDNode *FieldNode;
+      if (isTBAAPathStruct(FieldQTy))
+        FieldNode = getTBAAStructTypeInfo(FieldQTy);
+      else {
+        FieldNode = getTBAAInfo(FieldQTy);
+        // Ignore this field if the type already exists.
+        if (ScalarFieldTypes.count(FieldNode))
+          continue;
+        ScalarFieldTypes.insert(FieldNode);
+       }
+      if (!FieldNode)
+        return StructTypeMetadataCache[Ty] = NULL;
+      Fields.push_back(std::make_pair(
+          Layout.getFieldOffset(idx) / Context.getCharWidth(), FieldNode));
+    }
+
+    // TODO: This is using the RTTI name. Is there a better way to get
+    // a unique string for a type?
+    SmallString<256> OutName;
+    llvm::raw_svector_ostream Out(OutName);
+    MContext.mangleCXXRTTIName(QualType(Ty, 0), Out);
+    Out.flush();
+    // Create the struct type node with a vector of pairs (offset, type).
+    return StructTypeMetadataCache[Ty] =
+      MDHelper.createTBAAStructTypeNode(OutName, Fields);
+  }
+
+  return StructMetadataCache[Ty] = NULL;
+}
+
+llvm::MDNode *
+CodeGenTBAA::getTBAAStructTagInfo(QualType BaseQTy, llvm::MDNode *AccessNode,
+                                  uint64_t Offset) {
+  if (!CodeGenOpts.StructPathTBAA)
+    return AccessNode;
+
+  const Type *BTy = Context.getCanonicalType(BaseQTy).getTypePtr();
+  TBAAPathTag PathTag = TBAAPathTag(BTy, AccessNode, Offset);
+  if (llvm::MDNode *N = StructTagMetadataCache[PathTag])
+    return N;
+
+  llvm::MDNode *BNode = 0;
+  if (isTBAAPathStruct(BaseQTy))
+    BNode  = getTBAAStructTypeInfo(BaseQTy);
+  if (!BNode)
+    return StructTagMetadataCache[PathTag] = AccessNode;
+
+  return StructTagMetadataCache[PathTag] =
+    MDHelper.createTBAAStructTagNode(BNode, AccessNode, Offset);
+}