Add support for a union type in LLVM IR. Patch by Talin!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@96011 91177308-0d34-0410-b5e6-96231b3b80d8

6 files changed, 125 insertions, 9 deletions

diff --git a/include/llvm-c/Core.h b/include/llvm-c/Core.h
index 98358fe380..4500fccb65 100644
--- a/include/llvm-c/Core.h
+++ b/include/llvm-c/Core.h
@@ -193,7 +193,8 @@ typedef enum {
   LLVMPointerTypeKind,     /**< Pointers */
   LLVMOpaqueTypeKind,      /**< Opaque: type with unknown structure */
   LLVMVectorTypeKind,      /**< SIMD 'packed' format, or other vector type */
-  LLVMMetadataTypeKind     /**< Metadata */
+  LLVMMetadataTypeKind,    /**< Metadata */
+  LLVMUnionTypeKind        /**< Unions */
 } LLVMTypeKind;
 
 typedef enum {
@@ -372,6 +373,13 @@ unsigned LLVMCountStructElementTypes(LLVMTypeRef StructTy);
 void LLVMGetStructElementTypes(LLVMTypeRef StructTy, LLVMTypeRef *Dest);
 LLVMBool LLVMIsPackedStruct(LLVMTypeRef StructTy);
 
+/* Operations on union types */
+LLVMTypeRef LLVMUnionTypeInContext(LLVMContextRef C, LLVMTypeRef *ElementTypes,
+                                   unsigned ElementCount);
+LLVMTypeRef LLVMUnionType(LLVMTypeRef *ElementTypes, unsigned ElementCount);
+unsigned LLVMCountUnionElementTypes(LLVMTypeRef UnionTy);
+void LLVMGetUnionElementTypes(LLVMTypeRef UnionTy, LLVMTypeRef *Dest);
+
 /* Operations on array, pointer, and vector types (sequence types) */
 LLVMTypeRef LLVMArrayType(LLVMTypeRef ElementType, unsigned ElementCount);
 LLVMTypeRef LLVMPointerType(LLVMTypeRef ElementType, unsigned AddressSpace);
diff --git a/include/llvm/Bitcode/LLVMBitCodes.h b/include/llvm/Bitcode/LLVMBitCodes.h
index 9bb50d4b3b..a980df8110 100644
--- a/include/llvm/Bitcode/LLVMBitCodes.h
+++ b/include/llvm/Bitcode/LLVMBitCodes.h
@@ -94,7 +94,8 @@ namespace bitc {
     TYPE_CODE_FP128    = 14,   // LONG DOUBLE (112 bit mantissa)
     TYPE_CODE_PPC_FP128= 15,   // PPC LONG DOUBLE (2 doubles)
 
-    TYPE_CODE_METADATA = 16    // METADATA
+    TYPE_CODE_METADATA = 16,   // METADATA
+    TYPE_CODE_UNION    = 17    // UNION: [eltty x N]
   };
 
   // The type symbol table only has one code (TST_ENTRY_CODE).
diff --git a/include/llvm/Constants.h b/include/llvm/Constants.h
index ff1be051bc..bd14303d67 100644
--- a/include/llvm/Constants.h
+++ b/include/llvm/Constants.h
@@ -33,6 +33,7 @@ namespace llvm {
 class ArrayType;
 class IntegerType;
 class StructType;
+class UnionType;
 class PointerType;
 class VectorType;
 
@@ -453,6 +454,50 @@ struct OperandTraits<ConstantStruct> : public VariadicOperandTraits<> {
 DEFINE_TRANSPARENT_CASTED_OPERAND_ACCESSORS(ConstantStruct, Constant)
 
 //===----------------------------------------------------------------------===//
+// ConstantUnion - Constant Union Declarations
+//
+class ConstantUnion : public Constant {
+  friend struct ConstantCreator<ConstantUnion, UnionType, Constant*>;
+  ConstantUnion(const ConstantUnion &);      // DO NOT IMPLEMENT
+protected:
+  ConstantUnion(const UnionType *T, Constant* Val);
+public:
+  // ConstantUnion accessors
+  static Constant *get(const UnionType *T, Constant* V);
+
+  /// Transparently provide more efficient getOperand methods.
+  DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Constant);
+  
+  /// getType() specialization - Reduce amount of casting...
+  ///
+  inline const UnionType *getType() const {
+    return reinterpret_cast<const UnionType*>(Value::getType());
+  }
+
+  /// isNullValue - Return true if this is the value that would be returned by
+  /// getNullValue.  This always returns false because zero structs are always
+  /// created as ConstantAggregateZero objects.
+  virtual bool isNullValue() const {
+    return false;
+  }
+
+  virtual void destroyConstant();
+  virtual void replaceUsesOfWithOnConstant(Value *From, Value *To, Use *U);
+
+  /// Methods for support type inquiry through isa, cast, and dyn_cast:
+  static inline bool classof(const ConstantUnion *) { return true; }
+  static bool classof(const Value *V) {
+    return V->getValueID() == ConstantUnionVal;
+  }
+};
+
+template <>
+struct OperandTraits<ConstantUnion> : public FixedNumOperandTraits<1> {
+};
+
+DEFINE_TRANSPARENT_CASTED_OPERAND_ACCESSORS(ConstantUnion, Constant)
+
+//===----------------------------------------------------------------------===//
 /// ConstantVector - Constant Vector Declarations
 ///
 class ConstantVector : public Constant {
diff --git a/include/llvm/DerivedTypes.h b/include/llvm/DerivedTypes.h
index 881fbc81e5..912bb6d882 100644
--- a/include/llvm/DerivedTypes.h
+++ b/include/llvm/DerivedTypes.h
@@ -27,6 +27,7 @@ template<class ValType, class TypeClass> class TypeMap;
 class FunctionValType;
 class ArrayValType;
 class StructValType;
+class UnionValType;
 class PointerValType;
 class VectorValType;
 class IntegerValType;
@@ -229,7 +230,8 @@ public:
     return T->getTypeID() == ArrayTyID ||
            T->getTypeID() == StructTyID ||
            T->getTypeID() == PointerTyID ||
-           T->getTypeID() == VectorTyID;
+           T->getTypeID() == VectorTyID ||
+           T->getTypeID() == UnionTyID;
   }
 };
 
@@ -301,6 +303,63 @@ public:
 };
 
 
+/// UnionType - Class to represent union types. A union type is similar to
+/// a structure, except that all member fields begin at offset 0.
+///
+class UnionType : public CompositeType {
+  friend class TypeMap<UnionValType, UnionType>;
+  UnionType(const UnionType &);                   // Do not implement
+  const UnionType &operator=(const UnionType &);  // Do not implement
+  UnionType(LLVMContext &C, const Type* const* Types, unsigned NumTypes);
+public:
+  /// UnionType::get - This static method is the primary way to create a
+  /// UnionType.
+  static UnionType *get(const Type* const* Types, unsigned NumTypes);
+
+  /// UnionType::get - This static method is a convenience method for
+  /// creating union types by specifying the elements as arguments.
+  static UnionType *get(const Type *type, ...) END_WITH_NULL;
+
+  /// isValidElementType - Return true if the specified type is valid as a
+  /// element type.
+  static bool isValidElementType(const Type *ElemTy);
+  
+  /// Given an element type, return the member index of that type, or -1
+  /// if there is no such member type.
+  int getElementTypeIndex(const Type *ElemTy) const;
+
+  // Iterator access to the elements
+  typedef Type::subtype_iterator element_iterator;
+  element_iterator element_begin() const { return ContainedTys; }
+  element_iterator element_end() const { return &ContainedTys[NumContainedTys];}
+
+  // Random access to the elements
+  unsigned getNumElements() const { return NumContainedTys; }
+  const Type *getElementType(unsigned N) const {
+    assert(N < NumContainedTys && "Element number out of range!");
+    return ContainedTys[N];
+  }
+
+  /// getTypeAtIndex - Given an index value into the type, return the type of
+  /// the element.  For a union type, this must be a constant value...
+  ///
+  virtual const Type *getTypeAtIndex(const Value *V) const;
+  virtual const Type *getTypeAtIndex(unsigned Idx) const;
+  virtual bool indexValid(const Value *V) const;
+  virtual bool indexValid(unsigned Idx) const;
+
+  // Implement the AbstractTypeUser interface.
+  virtual void refineAbstractType(const DerivedType *OldTy, const Type *NewTy);
+  virtual void typeBecameConcrete(const DerivedType *AbsTy);
+
+  // Methods for support type inquiry through isa, cast, and dyn_cast:
+  static inline bool classof(const UnionType *) { return true; }
+  static inline bool classof(const Type *T) {
+    return T->getTypeID() == UnionTyID;
+  }
+};
+
+
 /// SequentialType - This is the superclass of the array, pointer and vector
 /// type classes.  All of these represent "arrays" in memory.  The array type
 /// represents a specifically sized array, pointer types are unsized/unknown
diff --git a/include/llvm/Type.h b/include/llvm/Type.h
index bc319c6537..52b2c845d8 100644
--- a/include/llvm/Type.h
+++ b/include/llvm/Type.h
@@ -82,10 +82,11 @@ public:
     IntegerTyID,     ///<  8: Arbitrary bit width integers
     FunctionTyID,    ///<  9: Functions
     StructTyID,      ///< 10: Structures
-    ArrayTyID,       ///< 11: Arrays
-    PointerTyID,     ///< 12: Pointers
-    OpaqueTyID,      ///< 13: Opaque: type with unknown structure
-    VectorTyID,      ///< 14: SIMD 'packed' format, or other vector type
+    UnionTyID,       ///< 11: Unions
+    ArrayTyID,       ///< 12: Arrays
+    PointerTyID,     ///< 13: Pointers
+    OpaqueTyID,      ///< 14: Opaque: type with unknown structure
+    VectorTyID,      ///< 15: SIMD 'packed' format, or other vector type
 
     NumTypeIDs,                         // Must remain as last defined ID
     LastPrimitiveTyID = LabelTyID,
@@ -297,7 +298,7 @@ public:
   /// does not include vector types.
   ///
   inline bool isAggregateType() const {
-    return ID == StructTyID || ID == ArrayTyID;
+    return ID == StructTyID || ID == ArrayTyID || ID == UnionTyID;
   }
 
   /// isSized - Return true if it makes sense to take the size of this type.  To
@@ -310,7 +311,8 @@ public:
       return true;
     // If it is not something that can have a size (e.g. a function or label),
     // it doesn't have a size.
-    if (ID != StructTyID && ID != ArrayTyID && ID != VectorTyID)
+    if (ID != StructTyID && ID != ArrayTyID && ID != VectorTyID &&
+        ID != UnionTyID)
       return false;
     // If it is something that can have a size and it's concrete, it definitely
     // has a size, otherwise we have to try harder to decide.
diff --git a/include/llvm/Value.h b/include/llvm/Value.h
index 9045906e7b..d06cbc05c6 100644
--- a/include/llvm/Value.h
+++ b/include/llvm/Value.h
@@ -215,6 +215,7 @@ public:
     ConstantFPVal,            // This is an instance of ConstantFP
     ConstantArrayVal,         // This is an instance of ConstantArray
     ConstantStructVal,        // This is an instance of ConstantStruct
+    ConstantUnionVal,         // This is an instance of ConstantUnion
     ConstantVectorVal,        // This is an instance of ConstantVector
     ConstantPointerNullVal,   // This is an instance of ConstantPointerNull
     MDNodeVal,                // This is an instance of MDNode