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

lib/Bitcode/Writer/BitcodeWriter.cpp

@@ -21,7 +21,6 @@
 #include "llvm/Instructions.h"
 #include "llvm/Module.h"
 #include "llvm/Operator.h"
-#include "llvm/TypeSymbolTable.h"
 #include "llvm/ValueSymbolTable.h"
 #include "llvm/ADT/Triple.h"
 #include "llvm/Support/ErrorHandling.h"
@@ -29,6 +28,7 @@
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Support/Program.h"
 #include <cctype>
+#include <map>
 using namespace llvm;
 
 /// These are manifest constants used by the bitcode writer. They do not need to
@@ -101,13 +101,16 @@ static unsigned GetEncodedBinaryOpcode(unsigned Opcode) {
   }
 }
 
-static void WriteStringRecord(unsigned Code, const std::string &Str,
+static void WriteStringRecord(unsigned Code, StringRef Str,
                               unsigned AbbrevToUse, BitstreamWriter &Stream) {
   SmallVector<unsigned, 64> Vals;
 
   // Code: [strchar x N]
-  for (unsigned i = 0, e = Str.size(); i != e; ++i)
+  for (unsigned i = 0, e = Str.size(); i != e; ++i) {
+    if (AbbrevToUse && !BitCodeAbbrevOp::isChar6(Str[i]))
+      AbbrevToUse = 0;
     Vals.push_back(Str[i]);
+  }
 
   // Emit the finished record.
   Stream.EmitRecord(Code, Vals, AbbrevToUse);
@@ -151,7 +154,7 @@ static void WriteAttributeTable(const ValueEnumerator &VE,
 static void WriteTypeTable(const ValueEnumerator &VE, BitstreamWriter &Stream) {
   const ValueEnumerator::TypeList &TypeList = VE.getTypes();
 
-  Stream.EnterSubblock(bitc::TYPE_BLOCK_ID, 4 /*count from # abbrevs */);
+  Stream.EnterSubblock(bitc::TYPE_BLOCK_ID_NEW, 4 /*count from # abbrevs */);
   SmallVector<uint64_t, 64> TypeVals;
 
   // Abbrev for TYPE_CODE_POINTER.
@@ -172,15 +175,32 @@ static void WriteTypeTable(const ValueEnumerator &VE, BitstreamWriter &Stream) {
                             Log2_32_Ceil(VE.getTypes().size()+1)));
   unsigned FunctionAbbrev = Stream.EmitAbbrev(Abbv);
 
-  // Abbrev for TYPE_CODE_STRUCT.
+  // Abbrev for TYPE_CODE_STRUCT_ANON.
   Abbv = new BitCodeAbbrev();
-  Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT));
+  Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_ANON));
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
                             Log2_32_Ceil(VE.getTypes().size()+1)));
-  unsigned StructAbbrev = Stream.EmitAbbrev(Abbv);
+  unsigned StructAnonAbbrev = Stream.EmitAbbrev(Abbv);
 
+  // Abbrev for TYPE_CODE_STRUCT_NAME.
+  Abbv = new BitCodeAbbrev();
+  Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAME));
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Char6));
+  unsigned StructNameAbbrev = Stream.EmitAbbrev(Abbv);
+
+  // Abbrev for TYPE_CODE_STRUCT_NAMED.
+  Abbv = new BitCodeAbbrev();
+  Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_STRUCT_NAMED));
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));  // ispacked
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
+                            Log2_32_Ceil(VE.getTypes().size()+1)));
+  unsigned StructNamedAbbrev = Stream.EmitAbbrev(Abbv);
+
+  
   // Abbrev for TYPE_CODE_ARRAY.
   Abbv = new BitCodeAbbrev();
   Abbv->Add(BitCodeAbbrevOp(bitc::TYPE_CODE_ARRAY));
@@ -202,16 +222,15 @@ static void WriteTypeTable(const ValueEnumerator &VE, BitstreamWriter &Stream) {
 
     switch (T->getTypeID()) {
     default: llvm_unreachable("Unknown type!");
-    case Type::VoidTyID:   Code = bitc::TYPE_CODE_VOID;   break;
-    case Type::FloatTyID:  Code = bitc::TYPE_CODE_FLOAT;  break;
-    case Type::DoubleTyID: Code = bitc::TYPE_CODE_DOUBLE; break;
-    case Type::X86_FP80TyID: Code = bitc::TYPE_CODE_X86_FP80; break;
-    case Type::FP128TyID: Code = bitc::TYPE_CODE_FP128; break;
+    case Type::VoidTyID:      Code = bitc::TYPE_CODE_VOID;   break;
+    case Type::FloatTyID:     Code = bitc::TYPE_CODE_FLOAT;  break;
+    case Type::DoubleTyID:    Code = bitc::TYPE_CODE_DOUBLE; break;
+    case Type::X86_FP80TyID:  Code = bitc::TYPE_CODE_X86_FP80; break;
+    case Type::FP128TyID:     Code = bitc::TYPE_CODE_FP128; break;
     case Type::PPC_FP128TyID: Code = bitc::TYPE_CODE_PPC_FP128; break;
-    case Type::LabelTyID:  Code = bitc::TYPE_CODE_LABEL;  break;
-    case Type::OpaqueTyID: Code = bitc::TYPE_CODE_OPAQUE; break;
-    case Type::MetadataTyID: Code = bitc::TYPE_CODE_METADATA; break;
-    case Type::X86_MMXTyID: Code = bitc::TYPE_CODE_X86_MMX; break;
+    case Type::LabelTyID:     Code = bitc::TYPE_CODE_LABEL;  break;
+    case Type::MetadataTyID:  Code = bitc::TYPE_CODE_METADATA; break;
+    case Type::X86_MMXTyID:   Code = bitc::TYPE_CODE_X86_MMX; break;
     case Type::IntegerTyID:
       // INTEGER: [width]
       Code = bitc::TYPE_CODE_INTEGER;
@@ -242,13 +261,28 @@ static void WriteTypeTable(const ValueEnumerator &VE, BitstreamWriter &Stream) {
     case Type::StructTyID: {
       const StructType *ST = cast<StructType>(T);
       // STRUCT: [ispacked, eltty x N]
-      Code = bitc::TYPE_CODE_STRUCT;
       TypeVals.push_back(ST->isPacked());
       // Output all of the element types.
       for (StructType::element_iterator I = ST->element_begin(),
            E = ST->element_end(); I != E; ++I)
         TypeVals.push_back(VE.getTypeID(*I));
-      AbbrevToUse = StructAbbrev;
+      
+      if (ST->isAnonymous()) {
+        Code = bitc::TYPE_CODE_STRUCT_ANON;
+        AbbrevToUse = StructAnonAbbrev;
+      } else {
+        if (ST->isOpaque()) {
+          Code = bitc::TYPE_CODE_OPAQUE;
+        } else {
+          Code = bitc::TYPE_CODE_STRUCT_NAMED;
+          AbbrevToUse = StructNamedAbbrev;
+        }
+
+        // Emit the name if it is present.
+        if (!ST->getName().empty())
+          WriteStringRecord(bitc::TYPE_CODE_STRUCT_NAME, ST->getName(),
+                            StructNameAbbrev, Stream);
+      }
       break;
     }
     case Type::ArrayTyID: {
@@ -1278,46 +1312,6 @@ static void WriteFunction(const Function &F, ValueEnumerator &VE,
   Stream.ExitBlock();
 }
 
-/// WriteTypeSymbolTable - Emit a block for the specified type symtab.
-static void WriteTypeSymbolTable(const TypeSymbolTable &TST,
-                                 const ValueEnumerator &VE,
-                                 BitstreamWriter &Stream) {
-  if (TST.empty()) return;
-
-  Stream.EnterSubblock(bitc::TYPE_SYMTAB_BLOCK_ID, 3);
-
-  // 7-bit fixed width VST_CODE_ENTRY strings.
-  BitCodeAbbrev *Abbv = new BitCodeAbbrev();
-  Abbv->Add(BitCodeAbbrevOp(bitc::VST_CODE_ENTRY));
-  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
-                            Log2_32_Ceil(VE.getTypes().size()+1)));
-  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
-  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 7));
-  unsigned V7Abbrev = Stream.EmitAbbrev(Abbv);
-
-  SmallVector<unsigned, 64> NameVals;
-
-  for (TypeSymbolTable::const_iterator TI = TST.begin(), TE = TST.end();
-       TI != TE; ++TI) {
-    // TST_ENTRY: [typeid, namechar x N]
-    NameVals.push_back(VE.getTypeID(TI->second));
-
-    const std::string &Str = TI->first;
-    bool is7Bit = true;
-    for (unsigned i = 0, e = Str.size(); i != e; ++i) {
-      NameVals.push_back((unsigned char)Str[i]);
-      if (Str[i] & 128)
-        is7Bit = false;
-    }
-
-    // Emit the finished record.
-    Stream.EmitRecord(bitc::VST_CODE_ENTRY, NameVals, is7Bit ? V7Abbrev : 0);
-    NameVals.clear();
-  }
-
-  Stream.ExitBlock();
-}
-
 // Emit blockinfo, which defines the standard abbreviations etc.
 static void WriteBlockInfo(const ValueEnumerator &VE, BitstreamWriter &Stream) {
   // We only want to emit block info records for blocks that have multiple
@@ -1521,9 +1515,6 @@ static void WriteModule(const Module *M, BitstreamWriter &Stream) {
   // Emit metadata.
   WriteModuleMetadataStore(M, Stream);
 
-  // Emit the type symbol table information.
-  WriteTypeSymbolTable(M->getTypeSymbolTable(), VE, Stream);
-
   // Emit names for globals/functions etc.
   WriteValueSymbolTable(M->getValueSymbolTable(), VE, Stream);