Land the long talked about "type system rewrite" patch. This

patch brings numerous advantages to LLVM.  One way to look at it
is through diffstat:
 109 files changed, 3005 insertions(+), 5906 deletions(-)

Removing almost 3K lines of code is a good thing.  Other advantages
include:

1. Value::getType() is a simple load that can be CSE'd, not a mutating
   union-find operation.
2. Types a uniqued and never move once created, defining away PATypeHolder.
3. Structs can be "named" now, and their name is part of the identity that
   uniques them.  This means that the compiler doesn't merge them structurally
   which makes the IR much less confusing.
4. Now that there is no way to get a cycle in a type graph without a named
   struct type, "upreferences" go away.
5. Type refinement is completely gone, which should make LTO much MUCH faster
   in some common cases with C++ code.
6. Types are now generally immutable, so we can use "Type *" instead 
   "const Type *" everywhere.

Downsides of this patch are that it removes some functions from the C API,
so people using those will have to upgrade to (not yet added) new API.  
"LLVM 3.0" is the right time to do this.

There are still some cleanups pending after this, this patch is large enough
as-is.




git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@134829 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Value.h

@@ -14,7 +14,6 @@
 #ifndef LLVM_VALUE_H
 #define LLVM_VALUE_H
 
-#include "llvm/AbstractTypeUser.h"
 #include "llvm/Use.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/Casting.h"
@@ -32,7 +31,6 @@ class GlobalVariable;
 class GlobalAlias;
 class InlineAsm;
 class ValueSymbolTable;
-class TypeSymbolTable;
 template<typename ValueTy> class StringMapEntry;
 template <typename ValueTy = Value>
 class AssertingVH;
@@ -43,6 +41,7 @@ class ValueHandleBase;
 class LLVMContext;
 class Twine;
 class MDNode;
+class Type;
 
 //===----------------------------------------------------------------------===//
 //                                 Value Class
@@ -77,12 +76,11 @@ private:
   /// This field is initialized to zero by the ctor.
   unsigned short SubclassData;
 
-  PATypeHolder VTy;
+  Type *VTy;
   Use *UseList;
 
   friend class ValueSymbolTable; // Allow ValueSymbolTable to directly mod Name.
   friend class ValueHandleBase;
-  friend class AbstractTypeUser;
   ValueName *Name;
 
   void operator=(const Value &);     // Do not implement
@@ -107,13 +105,13 @@ public:
 
   /// All values are typed, get the type of this value.
   ///
-  inline const Type *getType() const { return VTy; }
+  Type *getType() const { return VTy; }
 
   /// All values hold a context through their type.
   LLVMContext &getContext() const;
 
   // All values can potentially be named...
-  inline bool hasName() const { return Name != 0; }
+  bool hasName() const { return Name != 0; }
   ValueName *getValueName() const { return Name; }
   
   /// getName() - Return a constant reference to the value's name. This is cheap
@@ -279,10 +277,6 @@ public:
     return true; // Values are always values.
   }
 
-  /// getRawType - This should only be used to implement the vmcore library.
-  ///
-  const Type *getRawType() const { return VTy.getRawType(); }
-
   /// stripPointerCasts - This method strips off any unneeded pointer
   /// casts from the specified value, returning the original uncasted value.
   /// Note that the returned value has pointer type if the specified value does.
@@ -310,6 +304,15 @@ public:
   /// load, store, and alloca instructions, and global values.
   static const unsigned MaximumAlignment = 1u << 29;
   
+  /// mutateType - Mutate the type of this Value to be of the specified type.
+  /// Note that this is an extremely dangerous operation which can create
+  /// completely invalid IR very easily.  It is strongly recommended that you
+  /// recreate IR objects with the right types instead of mutating them in
+  /// place.
+  void mutateType(Type *Ty) {
+    VTy = Ty;
+  }
+  
 protected:
   unsigned short getSubclassDataFromValue() const { return SubclassData; }
   void setValueSubclassData(unsigned short D) { SubclassData = D; }