Experimental TBAA support.

This enables metadata generation by default, however the TBAA pass
in the optimizer is still disabled for now.

llvm-svn: 116536

1 files changed, 68 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/CodeGenTBAA.cpp b/clang/lib/CodeGen/CodeGenTBAA.cpp
new file mode 100644
index 00000000000..0039db81b46
--- /dev/null
+++ b/clang/lib/CodeGen/CodeGenTBAA.cpp
@@ -0,0 +1,68 @@
+//===--- 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.
+//
+//===----------------------------------------------------------------------===//
+
+#include "CodeGenTBAA.h"
+#include "clang/AST/ASTContext.h"
+#include "llvm/LLVMContext.h"
+#include "llvm/Metadata.h"
+using namespace clang;
+using namespace CodeGen;
+
+CodeGenTBAA::CodeGenTBAA(ASTContext &Ctx, llvm::LLVMContext& VMContext,
+                         const LangOptions &Features)
+  : Context(Ctx), VMContext(VMContext), Features(Features), Root(0), Char(0) {
+}
+
+CodeGenTBAA::~CodeGenTBAA() {
+}
+
+llvm::MDNode *CodeGenTBAA::getTBAAInfoForNamedType(const char *NameStr,
+                                                   llvm::MDNode *Parent) {
+  llvm::Value *Ops[] = {
+    llvm::MDString::get(VMContext, NameStr),
+    Parent
+  };
+
+  return llvm::MDNode::get(VMContext, Ops, llvm::array_lengthof(Ops));
+}
+
+llvm::MDNode *
+CodeGenTBAA::getTBAAInfo(QualType QTy) {
+  Type *Ty = Context.getCanonicalType(QTy).getTypePtr();
+
+  if (llvm::MDNode *N = MetadataCache[Ty])
+    return N;
+
+  if (!Root) {
+    Root = getTBAAInfoForNamedType("Experimental TBAA", 0);
+    Char = getTBAAInfoForNamedType("omnipotent char", Root);
+  }
+
+  // For now, just emit a very minimal tree.
+  const Type *CanonicalTy = Context.getCanonicalType(Ty);
+  if (const BuiltinType *BTy = dyn_cast<BuiltinType>(CanonicalTy)) {
+    switch (BTy->getKind()) {
+    case BuiltinType::Char_U:
+    case BuiltinType::Char_S:
+    case BuiltinType::UChar:
+    case BuiltinType::SChar:
+      // Charactar types are special.
+      return Char;
+    default:
+      return MetadataCache[Ty] =
+               getTBAAInfoForNamedType(BTy->getName(Features), Char);
+    }
+  }
+
+  return MetadataCache[Ty] = getTBAAInfoForNamedType("TBAA.other", Char);
+}