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

1 files changed, 56 insertions, 161 deletions

diff --git a/lib/Target/CBackend/CBackend.cpp b/lib/Target/CBackend/CBackend.cpp
index c59497efc2..54072b2f8d 100644
--- a/lib/Target/CBackend/CBackend.cpp
+++ b/lib/Target/CBackend/CBackend.cpp
@@ -20,7 +20,6 @@
 #include "llvm/Instructions.h"
 #include "llvm/Pass.h"
 #include "llvm/PassManager.h"
-#include "llvm/TypeSymbolTable.h"
 #include "llvm/Intrinsics.h"
 #include "llvm/IntrinsicInst.h"
 #include "llvm/InlineAsm.h"
@@ -74,29 +73,6 @@ namespace {
       PrivateGlobalPrefix = "";
     }
   };
-  /// CBackendNameAllUsedStructsAndMergeFunctions - This pass inserts names for
-  /// any unnamed structure types that are used by the program, and merges
-  /// external functions with the same name.
-  ///
-  class CBackendNameAllUsedStructsAndMergeFunctions : public ModulePass {
-  public:
-    static char ID;
-    CBackendNameAllUsedStructsAndMergeFunctions()
-        : ModulePass(ID) {
-          initializeFindUsedTypesPass(*PassRegistry::getPassRegistry());
-        }
-    void getAnalysisUsage(AnalysisUsage &AU) const {
-      AU.addRequired<FindUsedTypes>();
-    }
-
-    virtual const char *getPassName() const {
-      return "C backend type canonicalizer";
-    }
-
-    virtual bool runOnModule(Module &M);
-  };
-
-  char CBackendNameAllUsedStructsAndMergeFunctions::ID = 0;
 
   /// CWriter - This class is the main chunk of code that converts an LLVM
   /// module to a C translation unit.
@@ -109,7 +85,7 @@ namespace {
     const MCAsmInfo* TAsm;
     MCContext *TCtx;
     const TargetData* TD;
-    std::map<const Type *, std::string> TypeNames;
+    
     std::map<const ConstantFP *, unsigned> FPConstantMap;
     std::set<Function*> intrinsicPrototypesAlreadyGenerated;
     std::set<const Argument*> ByValParams;
@@ -118,6 +94,10 @@ namespace {
     DenseMap<const Value*, unsigned> AnonValueNumbers;
     unsigned NextAnonValueNumber;
 
+    /// UnnamedStructIDs - This contains a unique ID for each struct that is
+    /// either anonymous or has no name.
+    DenseMap<const StructType*, unsigned> UnnamedStructIDs;
+    
   public:
     static char ID;
     explicit CWriter(formatted_raw_ostream &o)
@@ -163,9 +143,9 @@ namespace {
       delete TCtx;
       delete TAsm;
       FPConstantMap.clear();
-      TypeNames.clear();
       ByValParams.clear();
       intrinsicPrototypesAlreadyGenerated.clear();
+      UnnamedStructIDs.clear();
       return false;
     }
 
@@ -182,6 +162,8 @@ namespace {
                                               const AttrListPtr &PAL,
                                               const PointerType *Ty);
 
+    std::string getStructName(const StructType *ST);
+    
     /// writeOperandDeref - Print the result of dereferencing the specified
     /// operand with '*'.  This is equivalent to printing '*' then using
     /// writeOperand, but avoids excess syntax in some cases.
@@ -214,8 +196,8 @@ namespace {
     /// intrinsics which need to be explicitly defined in the CBackend.
     void printIntrinsicDefinition(const Function &F, raw_ostream &Out);
 
-    void printModuleTypes(const TypeSymbolTable &ST);
-    void printContainedStructs(const Type *Ty, std::set<const Type *> &);
+    void printModuleTypes();
+    void printContainedStructs(const Type *Ty, SmallPtrSet<const Type *, 16> &);
     void printFloatingPointConstants(Function &F);
     void printFloatingPointConstants(const Constant *C);
     void printFunctionSignature(const Function *F, bool Prototype);
@@ -359,6 +341,7 @@ namespace {
 char CWriter::ID = 0;
 
 
+
 static std::string CBEMangle(const std::string &S) {
   std::string Result;
 
@@ -374,90 +357,14 @@ static std::string CBEMangle(const std::string &S) {
   return Result;
 }
 
-
-/// This method inserts names for any unnamed structure types that are used by
-/// the program, and removes names from structure types that are not used by the
-/// program.
-///
-bool CBackendNameAllUsedStructsAndMergeFunctions::runOnModule(Module &M) {
-  // Get a set of types that are used by the program...
-  SetVector<const Type *> UT = getAnalysis<FindUsedTypes>().getTypes();
-
-  // Loop over the module symbol table, removing types from UT that are
-  // already named, and removing names for types that are not used.
-  //
-  TypeSymbolTable &TST = M.getTypeSymbolTable();
-  for (TypeSymbolTable::iterator TI = TST.begin(), TE = TST.end();
-       TI != TE; ) {
-    TypeSymbolTable::iterator I = TI++;
-
-    // If this isn't a struct or array type, remove it from our set of types
-    // to name. This simplifies emission later.
-    if (!I->second->isStructTy() && !I->second->isOpaqueTy() &&
-        !I->second->isArrayTy()) {
-      TST.remove(I);
-    } else {
-      // If this is not used, remove it from the symbol table.
-      if (!UT.count(I->second))
-        TST.remove(I);
-      else
-        UT.remove(I->second); // Only keep one name for this type.
-    }
-  }
-
-  // UT now contains types that are not named.  Loop over it, naming
-  // structure types.
-  //
-  bool Changed = false;
-  unsigned RenameCounter = 0;
-  for (SetVector<const Type *>::const_iterator I = UT.begin(), E = UT.end();
-       I != E; ++I)
-    if ((*I)->isStructTy() || (*I)->isArrayTy()) {
-      while (M.addTypeName("unnamed"+utostr(RenameCounter), *I))
-        ++RenameCounter;
-      Changed = true;
-    }
-
-
-  // Loop over all external functions and globals.  If we have two with
-  // identical names, merge them.
-  // FIXME: This code should disappear when we don't allow values with the same
-  // names when they have different types!
-  std::map<std::string, GlobalValue*> ExtSymbols;
-  for (Module::iterator I = M.begin(), E = M.end(); I != E;) {
-    Function *GV = I++;
-    if (GV->isDeclaration() && GV->hasName()) {
-      std::pair<std::map<std::string, GlobalValue*>::iterator, bool> X
-        = ExtSymbols.insert(std::make_pair(GV->getName(), GV));
-      if (!X.second) {
-        // Found a conflict, replace this global with the previous one.
-        GlobalValue *OldGV = X.first->second;
-        GV->replaceAllUsesWith(ConstantExpr::getBitCast(OldGV, GV->getType()));
-        GV->eraseFromParent();
-        Changed = true;
-      }
-    }
-  }
-  // Do the same for globals.
-  for (Module::global_iterator I = M.global_begin(), E = M.global_end();
-       I != E;) {
-    GlobalVariable *GV = I++;
-    if (GV->isDeclaration() && GV->hasName()) {
-      std::pair<std::map<std::string, GlobalValue*>::iterator, bool> X
-        = ExtSymbols.insert(std::make_pair(GV->getName(), GV));
-      if (!X.second) {
-        // Found a conflict, replace this global with the previous one.
-        GlobalValue *OldGV = X.first->second;
-        GV->replaceAllUsesWith(ConstantExpr::getBitCast(OldGV, GV->getType()));
-        GV->eraseFromParent();
-        Changed = true;
-      }
-    }
-  }
-
-  return Changed;
+std::string CWriter::getStructName(const StructType *ST) {
+  if (!ST->isAnonymous() && !ST->getName().empty())
+    return CBEMangle("l_"+ST->getName().str());
+  
+  return "l_unnamed_" + utostr(UnnamedStructIDs[ST]);
 }
 
+
 /// printStructReturnPointerFunctionType - This is like printType for a struct
 /// return type, except, instead of printing the type as void (*)(Struct*, ...)
 /// print it as "Struct (*)(...)", for struct return functions.
@@ -471,7 +378,7 @@ void CWriter::printStructReturnPointerFunctionType(raw_ostream &Out,
   bool PrintedType = false;
 
   FunctionType::param_iterator I = FTy->param_begin(), E = FTy->param_end();
-  const Type *RetTy = cast<PointerType>(I->get())->getElementType();
+  const Type *RetTy = cast<PointerType>(*I)->getElementType();
   unsigned Idx = 1;
   for (++I, ++Idx; I != E; ++I, ++Idx) {
     if (PrintedType)
@@ -559,12 +466,6 @@ raw_ostream &CWriter::printType(raw_ostream &Out, const Type *Ty,
     return Out;
   }
 
-  // Check to see if the type is named.
-  if (!IgnoreName || Ty->isOpaqueTy()) {
-    std::map<const Type *, std::string>::iterator I = TypeNames.find(Ty);
-    if (I != TypeNames.end()) return Out << I->second << ' ' << NameSoFar;
-  }
-
   switch (Ty->getTypeID()) {
   case Type::FunctionTyID: {
     const FunctionType *FTy = cast<FunctionType>(Ty);
@@ -599,6 +500,11 @@ raw_ostream &CWriter::printType(raw_ostream &Out, const Type *Ty,
   }
   case Type::StructTyID: {
     const StructType *STy = cast<StructType>(Ty);
+    
+    // Check to see if the type is named.
+    if (!IgnoreName)
+      return Out << getStructName(STy) << ' ' << NameSoFar;
+    
     Out << NameSoFar + " {\n";
     unsigned Idx = 0;
     for (StructType::element_iterator I = STy->element_begin(),
@@ -639,12 +545,6 @@ raw_ostream &CWriter::printType(raw_ostream &Out, const Type *Ty,
     return Out << "; }";
   }
 
-  case Type::OpaqueTyID: {
-    std::string TyName = "struct opaque_" + itostr(OpaqueCounter++);
-    assert(TypeNames.find(Ty) == TypeNames.end());
-    TypeNames[Ty] = TyName;
-    return Out << TyName << ' ' << NameSoFar;
-  }
   default:
     llvm_unreachable("Unhandled case in getTypeProps!");
   }
@@ -1829,8 +1729,8 @@ bool CWriter::doInitialization(Module &M) {
         << "/* End Module asm statements */\n";
   }
 
-  // Loop over the symbol table, emitting all named constants...
-  printModuleTypes(M.getTypeSymbolTable());
+  // Loop over the symbol table, emitting all named constants.
+  printModuleTypes();
 
   // Global variable declarations...
   if (!M.global_empty()) {
@@ -2119,11 +2019,10 @@ void CWriter::printFloatingPointConstants(const Constant *C) {
 }
 
 
-
 /// printSymbolTable - Run through symbol table looking for type names.  If a
 /// type name is found, emit its declaration...
 ///
-void CWriter::printModuleTypes(const TypeSymbolTable &TST) {
+void CWriter::printModuleTypes() {
   Out << "/* Helper union for bitcasts */\n";
   Out << "typedef union {\n";
   Out << "  unsigned int Int32;\n";
@@ -2132,46 +2031,42 @@ void CWriter::printModuleTypes(const TypeSymbolTable &TST) {
   Out << "  double Double;\n";
   Out << "} llvmBitCastUnion;\n";
 
-  // We are only interested in the type plane of the symbol table.
-  TypeSymbolTable::const_iterator I   = TST.begin();
-  TypeSymbolTable::const_iterator End = TST.end();
+  // Get all of the struct types used in the module.
+  std::vector<StructType*> StructTypes;
+  TheModule->findUsedStructTypes(StructTypes);
 
-  // If there are no type names, exit early.
-  if (I == End) return;
+  if (StructTypes.empty()) return;
 
-  // Print out forward declarations for structure types before anything else!
   Out << "/* Structure forward decls */\n";
-  for (; I != End; ++I) {
-    std::string Name = "struct " + CBEMangle("l_"+I->first);
-    Out << Name << ";\n";
-    TypeNames.insert(std::make_pair(I->second, Name));
-  }
 
-  Out << '\n';
+  unsigned NextTypeID = 0;
+  
+  // If any of them are missing names, add a unique ID to UnnamedStructIDs.
+  // Print out forward declarations for structure types.
+  for (unsigned i = 0, e = StructTypes.size(); i != e; ++i) {
+    StructType *ST = StructTypes[i];
 
-  // Now we can print out typedefs.  Above, we guaranteed that this can only be
-  // for struct or opaque types.
-  Out << "/* Typedefs */\n";
-  for (I = TST.begin(); I != End; ++I) {
-    std::string Name = CBEMangle("l_"+I->first);
-    Out << "typedef ";
-    printType(Out, I->second, false, Name);
-    Out << ";\n";
+    if (ST->isAnonymous() || ST->getName().empty())
+      UnnamedStructIDs[ST] = NextTypeID++;
+
+    std::string Name = getStructName(ST);
+
+    Out << "typedef struct " << Name << ' ' << Name << ";\n";
   }
 
   Out << '\n';
 
-  // Keep track of which structures have been printed so far...
-  std::set<const Type *> StructPrinted;
+  // Keep track of which structures have been printed so far.
+  SmallPtrSet<const Type *, 16> StructPrinted;
 
   // Loop over all structures then push them into the stack so they are
   // printed in the correct order.
   //
   Out << "/* Structure contents */\n";
-  for (I = TST.begin(); I != End; ++I)
-    if (I->second->isStructTy() || I->second->isArrayTy())
+  for (unsigned i = 0, e = StructTypes.size(); i != e; ++i)
+    if (StructTypes[i]->isStructTy())
       // Only print out used types!
-      printContainedStructs(I->second, StructPrinted);
+      printContainedStructs(StructTypes[i], StructPrinted);
 }
 
 // Push the struct onto the stack and recursively push all structs
@@ -2180,7 +2075,7 @@ void CWriter::printModuleTypes(const TypeSymbolTable &TST) {
 // TODO:  Make this work properly with vector types
 //
 void CWriter::printContainedStructs(const Type *Ty,
-                                    std::set<const Type*> &StructPrinted) {
+                                SmallPtrSet<const Type *, 16> &StructPrinted) {
   // Don't walk through pointers.
   if (Ty->isPointerTy() || Ty->isPrimitiveType() || Ty->isIntegerTy())
     return;
@@ -2190,14 +2085,13 @@ void CWriter::printContainedStructs(const Type *Ty,
        E = Ty->subtype_end(); I != E; ++I)
     printContainedStructs(*I, StructPrinted);
 
-  if (Ty->isStructTy() || Ty->isArrayTy()) {
+  if (const StructType *ST = dyn_cast<StructType>(Ty)) {
     // Check to see if we have already printed this struct.
-    if (StructPrinted.insert(Ty).second) {
-      // Print structure type out.
-      std::string Name = TypeNames[Ty];
-      printType(Out, Ty, false, Name, true);
-      Out << ";\n\n";
-    }
+    if (!StructPrinted.insert(Ty)) return;
+    
+    // Print structure type out.
+    printType(Out, ST, false, getStructName(ST), true);
+    Out << ";\n\n";
   }
 }
 
@@ -2847,10 +2741,12 @@ static void printLimitValue(const IntegerType &Ty, bool isSigned, bool isMax,
     Out << "U" << type << (isMax ? "_MAX" : "0");
 }
 
+#ifndef NDEBUG
 static bool isSupportedIntegerSize(const IntegerType &T) {
   return T.getBitWidth() == 8 || T.getBitWidth() == 16 ||
          T.getBitWidth() == 32 || T.getBitWidth() == 64;
 }
+#endif
 
 void CWriter::printIntrinsicDefinition(const Function &F, raw_ostream &Out) {
   const FunctionType *funT = F.getFunctionType();
@@ -3704,7 +3600,6 @@ bool CTargetMachine::addPassesToEmitFile(PassManagerBase &PM,
   PM.add(createGCLoweringPass());
   PM.add(createLowerInvokePass());
   PM.add(createCFGSimplificationPass());   // clean up after lower invoke.
-  PM.add(new CBackendNameAllUsedStructsAndMergeFunctions());
   PM.add(new CWriter(o));
   PM.add(createGCInfoDeleter());
   return false;