Struct-path aware TBAA: uniformize scalar tag and path tag.

For struct-path aware TBAA, we used to use scalar type node as the scalar tag,
which has an incompatible format with the struct path tag. We now use the same
format: base type, access type and offset.

We also uniformize the scalar type node and the struct type node: name, a list
of pairs (offset + pointer to MDNode). For scalar type, we have a single pair.
These are to make implementaiton of aliasing rules easier.

llvm-svn: 179335

1 files changed, 7 insertions, 2 deletions

diff --git a/clang/lib/CodeGen/CodeGenModule.h b/clang/lib/CodeGen/CodeGenModule.h
index 6bc44563fae..f8b09711f78 100644
--- a/clang/lib/CodeGen/CodeGenModule.h
+++ b/clang/lib/CodeGen/CodeGenModule.h
@@ -519,8 +519,13 @@ public:
   bool isPaddedAtomicType(QualType type);
   bool isPaddedAtomicType(const AtomicType *type);
 
-  static void DecorateInstruction(llvm::Instruction *Inst,
-                                  llvm::MDNode *TBAAInfo);
+  /// Decorate the instruction with a TBAA tag. For scalar TBAA, the tag
+  /// is the same as the type. For struct-path aware TBAA, the tag
+  /// is different from the type: base type, access type and offset.
+  /// When ConvertTypeToTag is true, we create a tag based on the scalar type.
+  void DecorateInstruction(llvm::Instruction *Inst,
+                           llvm::MDNode *TBAAInfo,
+                           bool ConvertTypeToTag = true);
 
   /// getSize - Emit the given number of characters as a value of type size_t.
   llvm::ConstantInt *getSize(CharUnits numChars);