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/Bitcode/LLVMBitCodes.h

@@ -29,13 +29,23 @@ namespace bitc {
 
     // Module sub-block id's.
     PARAMATTR_BLOCK_ID,
-    TYPE_BLOCK_ID,
+    
+    /// TYPE_BLOCK_ID_OLD - This is the type descriptor block in LLVM 2.9 and
+    /// earlier, replaced with TYPE_BLOCK_ID2.  FIXME: Remove in LLVM 3.1.
+    TYPE_BLOCK_ID_OLD,
+    
     CONSTANTS_BLOCK_ID,
     FUNCTION_BLOCK_ID,
-    TYPE_SYMTAB_BLOCK_ID,
+    
+    /// TYPE_SYMTAB_BLOCK_ID_OLD - This type descriptor is from LLVM 2.9 and
+    /// earlier bitcode files.  FIXME: Remove in LLVM 3.1
+    TYPE_SYMTAB_BLOCK_ID_OLD,
+    
     VALUE_SYMTAB_BLOCK_ID,
     METADATA_BLOCK_ID,
-    METADATA_ATTACHMENT_ID
+    METADATA_ATTACHMENT_ID,
+    
+    TYPE_BLOCK_ID_NEW
   };
 
 
@@ -72,31 +82,38 @@ namespace bitc {
 
   /// TYPE blocks have codes for each type primitive they use.
   enum TypeCodes {
-    TYPE_CODE_NUMENTRY =  1,   // NUMENTRY: [numentries]
+    TYPE_CODE_NUMENTRY =  1,    // NUMENTRY: [numentries]
 
     // Type Codes
-    TYPE_CODE_VOID     =  2,   // VOID
-    TYPE_CODE_FLOAT    =  3,   // FLOAT
-    TYPE_CODE_DOUBLE   =  4,   // DOUBLE
-    TYPE_CODE_LABEL    =  5,   // LABEL
-    TYPE_CODE_OPAQUE   =  6,   // OPAQUE
-    TYPE_CODE_INTEGER  =  7,   // INTEGER: [width]
-    TYPE_CODE_POINTER  =  8,   // POINTER: [pointee type]
-    TYPE_CODE_FUNCTION =  9,   // FUNCTION: [vararg, retty, paramty x N]
-    TYPE_CODE_STRUCT   = 10,   // STRUCT: [ispacked, eltty x N]
-    TYPE_CODE_ARRAY    = 11,   // ARRAY: [numelts, eltty]
-    TYPE_CODE_VECTOR   = 12,   // VECTOR: [numelts, eltty]
+    TYPE_CODE_VOID     =  2,    // VOID
+    TYPE_CODE_FLOAT    =  3,    // FLOAT
+    TYPE_CODE_DOUBLE   =  4,    // DOUBLE
+    TYPE_CODE_LABEL    =  5,    // LABEL
+    TYPE_CODE_OPAQUE   =  6,    // OPAQUE
+    TYPE_CODE_INTEGER  =  7,    // INTEGER: [width]
+    TYPE_CODE_POINTER  =  8,    // POINTER: [pointee type]
+    TYPE_CODE_FUNCTION =  9,    // FUNCTION: [vararg, retty, paramty x N]
+    
+    // FIXME: This is the encoding used for structs in LLVM 2.9 and earlier.
+    // REMOVE this in LLVM 3.1
+    TYPE_CODE_STRUCT_OLD = 10,  // STRUCT: [ispacked, eltty x N]
+    TYPE_CODE_ARRAY    = 11,    // ARRAY: [numelts, eltty]
+    TYPE_CODE_VECTOR   = 12,    // VECTOR: [numelts, eltty]
 
     // These are not with the other floating point types because they're
     // a late addition, and putting them in the right place breaks
     // binary compatibility.
-    TYPE_CODE_X86_FP80 = 13,   // X86 LONG DOUBLE
-    TYPE_CODE_FP128    = 14,   // LONG DOUBLE (112 bit mantissa)
-    TYPE_CODE_PPC_FP128= 15,   // PPC LONG DOUBLE (2 doubles)
+    TYPE_CODE_X86_FP80 = 13,    // X86 LONG DOUBLE
+    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_X86_MMX = 17     // X86 MMX
+    TYPE_CODE_X86_MMX = 17,     // X86 MMX
+    
+    TYPE_CODE_STRUCT_ANON = 18, // STRUCT_ANON: [ispacked, eltty x N]
+    TYPE_CODE_STRUCT_NAME = 19, // STRUCT_NAME: [strchr x N]
+    TYPE_CODE_STRUCT_NAMED = 20 // STRUCT_NAMED: [ispacked, eltty x N]
   };
 
   // The type symbol table only has one code (TST_ENTRY_CODE).