lib/Bytecode/Writer/SlotCalculator.cpp - platform/external/llvm - Gitiles

 //===-- SlotCalculator.cpp - Calculate what slots values land in ----------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file was developed by the LLVM research group and is distributed under
 // the University of Illinois Open Source License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file implements a useful analysis step to figure out what numbered slots
 // values in a program will land in (keeping track of per plane information).
 //
 // This is used when writing a file to disk, either in bytecode or assembly.
 //
 //===----------------------------------------------------------------------===//

 #include "SlotCalculator.h"
 #include "llvm/Constants.h"
 #include "llvm/DerivedTypes.h"
 #include "llvm/Function.h"
 #include "llvm/InlineAsm.h"
 #include "llvm/Instructions.h"
 #include "llvm/Module.h"
 #include "llvm/TypeSymbolTable.h"
 #include "llvm/Type.h"
 #include "llvm/ValueSymbolTable.h"
 #include "llvm/ADT/STLExtras.h"
 #include <algorithm>
 #include <functional>
 using namespace llvm;

 #ifndef NDEBUG
 #include "llvm/Support/Streams.h"
 #include "llvm/Support/CommandLine.h"
 static cl::opt<bool> SlotCalculatorDebugOption("scdebug",cl::init(false),
     cl::desc("Enable SlotCalculator debug output"), cl::Hidden);
 #define SC_DEBUG(X) if (SlotCalculatorDebugOption) cerr << X
 #else
 #define SC_DEBUG(X)
 #endif

 void SlotCalculator::insertPrimitives() {
   // Preload the table with the built-in types. These built-in types are
   // inserted first to ensure that they have low integer indices which helps to
   // keep bytecode sizes small. Note that the first group of indices must match
   // the Type::TypeIDs for the primitive types. After that the integer types are
   // added, but the order and value is not critical. What is critical is that
   // the indices of these "well known" slot numbers be properly maintained in
   // Reader.h which uses them directly to extract values of these types.
   SC_DEBUG("Inserting primitive types:\n");
                                     // See WellKnownTypeSlots in Reader.h
   getOrCreateTypeSlot(Type::VoidTy  ); // 0: VoidTySlot
   getOrCreateTypeSlot(Type::FloatTy ); // 1: FloatTySlot
   getOrCreateTypeSlot(Type::DoubleTy); // 2: DoubleTySlot
   getOrCreateTypeSlot(Type::LabelTy ); // 3: LabelTySlot
   assert(TypeMap.size() == Type::FirstDerivedTyID &&"Invalid primitive insert");
   // Above here *must* correspond 1:1 with the primitive types.
   getOrCreateTypeSlot(Type::Int1Ty  ); // 4: Int1TySlot
   getOrCreateTypeSlot(Type::Int8Ty  ); // 5: Int8TySlot
   getOrCreateTypeSlot(Type::Int16Ty ); // 6: Int16TySlot
   getOrCreateTypeSlot(Type::Int32Ty ); // 7: Int32TySlot
   getOrCreateTypeSlot(Type::Int64Ty ); // 8: Int64TySlot
 }

 SlotCalculator::SlotCalculator(const Module *M) {
   assert(M);
   TheModule = M;

   insertPrimitives();
   processModule();
 }

 // processModule - Process all of the module level function declarations and
 // types that are available.
 //
 void SlotCalculator::processModule() {
   SC_DEBUG("begin processModule!\n");

   // Add all of the global variables to the value table...
   //
   for (Module::const_global_iterator I = TheModule->global_begin(),
          E = TheModule->global_end(); I != E; ++I)
     CreateSlotIfNeeded(I);

   // Scavenge the types out of the functions, then add the functions themselves
   // to the value table...
   //
   for (Module::const_iterator I = TheModule->begin(), E = TheModule->end();
        I != E; ++I)
     CreateSlotIfNeeded(I);

   // Add all of the module level constants used as initializers
   //
   for (Module::const_global_iterator I = TheModule->global_begin(),
          E = TheModule->global_end(); I != E; ++I)
     if (I->hasInitializer())
       CreateSlotIfNeeded(I->getInitializer());

   // Now that all global constants have been added, rearrange constant planes
   // that contain constant strings so that the strings occur at the start of the
   // plane, not somewhere in the middle.
   //
   for (unsigned plane = 0, e = Table.size(); plane != e; ++plane) {
     if (const ArrayType *AT = dyn_cast<ArrayType>(Types[plane]))
       if (AT->getElementType() == Type::Int8Ty) {
         TypePlane &Plane = Table[plane];
         unsigned FirstNonStringID = 0;
         for (unsigned i = 0, e = Plane.size(); i != e; ++i)
           if (isa<ConstantAggregateZero>(Plane[i]) ||
               (isa<ConstantArray>(Plane[i]) &&
                cast<ConstantArray>(Plane[i])->isString())) {
             // Check to see if we have to shuffle this string around.  If not,
             // don't do anything.
             if (i != FirstNonStringID) {
               // Swap the plane entries....
               std::swap(Plane[i], Plane[FirstNonStringID]);

               // Keep the NodeMap up to date.
               NodeMap[Plane[i]] = i;
               NodeMap[Plane[FirstNonStringID]] = FirstNonStringID;
             }
             ++FirstNonStringID;
           }
       }
   }

   // Scan all of the functions for their constants, which allows us to emit
   // more compact modules.
   SC_DEBUG("Inserting function constants:\n");
   for (Module::const_iterator F = TheModule->begin(), E = TheModule->end();
        F != E; ++F) {
     for (Function::const_iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
       for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I!=E;++I){
         for (User::const_op_iterator OI = I->op_begin(), E = I->op_end();
              OI != E; ++OI) {
           if ((isa<Constant>(*OI) && !isa<GlobalValue>(*OI)) ||
               isa<InlineAsm>(*OI))
             CreateSlotIfNeeded(*OI);
         }
         getOrCreateTypeSlot(I->getType());
       }
   }

   // Insert constants that are named at module level into the slot pool so that
   // the module symbol table can refer to them...
   SC_DEBUG("Inserting SymbolTable values:\n");
   processTypeSymbolTable(&TheModule->getTypeSymbolTable());
   processValueSymbolTable(&TheModule->getValueSymbolTable());

   // Now that we have collected together all of the information relevant to the
   // module, compactify the type table if it is particularly big and outputting
   // a bytecode file.  The basic problem we run into is that some programs have
   // a large number of types, which causes the type field to overflow its size,
   // which causes instructions to explode in size (particularly call
   // instructions).  To avoid this behavior, we "sort" the type table so that
   // all non-value types are pushed to the end of the type table, giving nice
   // low numbers to the types that can be used by instructions, thus reducing
   // the amount of explodage we suffer.
   if (Types.size() >= 64) {
     unsigned FirstNonValueTypeID = 0;
     for (unsigned i = 0, e = Types.size(); i != e; ++i)
       if (Types[i]->isFirstClassType() || Types[i]->isPrimitiveType()) {
         // Check to see if we have to shuffle this type around.  If not, don't
         // do anything.
         if (i != FirstNonValueTypeID) {
           // Swap the type ID's.
           std::swap(Types[i], Types[FirstNonValueTypeID]);

           // Keep the TypeMap up to date.
           TypeMap[Types[i]] = i;
           TypeMap[Types[FirstNonValueTypeID]] = FirstNonValueTypeID;

           // When we move a type, make sure to move its value plane as needed.
           if (Table.size() > FirstNonValueTypeID) {
             if (Table.size() <= i) Table.resize(i+1);
             std::swap(Table[i], Table[FirstNonValueTypeID]);
           }
         }
         ++FirstNonValueTypeID;
       }
   }

   NumModuleTypes = getNumPlanes();

   SC_DEBUG("end processModule!\n");
 }

 // processTypeSymbolTable - Insert all of the type sin the specified symbol
 // table.
 void SlotCalculator::processTypeSymbolTable(const TypeSymbolTable *TST) {
   for (TypeSymbolTable::const_iterator TI = TST->begin(), TE = TST->end();
        TI != TE; ++TI )
     getOrCreateTypeSlot(TI->second);
 }

 // processSymbolTable - Insert all of the values in the specified symbol table
 // into the values table...
 //
 void SlotCalculator::processValueSymbolTable(const ValueSymbolTable *VST) {
   for (ValueSymbolTable::const_iterator VI = VST->begin(), VE = VST->end();
        VI != VE; ++VI)
     CreateSlotIfNeeded(VI->getValue());
 }

 void SlotCalculator::CreateSlotIfNeeded(const Value *V) {
   // Check to see if it's already in!
   if (NodeMap.count(V)) return;

   const Type *Ty = V->getType();
   assert(Ty != Type::VoidTy && "Can't insert void values!");

   if (const Constant *C = dyn_cast<Constant>(V)) {
     if (isa<GlobalValue>(C)) {
       // Initializers for globals are handled explicitly elsewhere.
     } else if (isa<ConstantArray>(C) && cast<ConstantArray>(C)->isString()) {
       // Do not index the characters that make up constant strings.  We emit
       // constant strings as special entities that don't require their
       // individual characters to be emitted.
       if (!C->isNullValue())
         ConstantStrings.push_back(cast<ConstantArray>(C));
     } else {
       // This makes sure that if a constant has uses (for example an array of
       // const ints), that they are inserted also.
       for (User::const_op_iterator I = C->op_begin(), E = C->op_end();
            I != E; ++I)
         CreateSlotIfNeeded(*I);
     }
   }

   unsigned TyPlane = getOrCreateTypeSlot(Ty);
   if (Table.size() <= TyPlane)    // Make sure we have the type plane allocated.
     Table.resize(TyPlane+1, TypePlane());

   // If this is the first value to get inserted into the type plane, make sure
   // to insert the implicit null value.
   if (Table[TyPlane].empty()) {
     // Label's and opaque types can't have a null value.
     if (Ty != Type::LabelTy && !isa<OpaqueType>(Ty)) {
       Value *ZeroInitializer = Constant::getNullValue(Ty);

       // If we are pushing zeroinit, it will be handled below.
       if (V != ZeroInitializer) {
         Table[TyPlane].push_back(ZeroInitializer);
         NodeMap[ZeroInitializer] = 0;
       }
     }
   }

   // Insert node into table and NodeMap...
   NodeMap[V] = Table[TyPlane].size();
   Table[TyPlane].push_back(V);

   SC_DEBUG("  Inserting value [" << TyPlane << "] = " << *V << " slot=" <<
            NodeMap[V] << "\n");
 }


 unsigned SlotCalculator::getOrCreateTypeSlot(const Type *Ty) {
   TypeMapType::iterator TyIt = TypeMap.find(Ty);
   if (TyIt != TypeMap.end()) return TyIt->second;

   // Insert into TypeMap.
   unsigned ResultSlot = TypeMap[Ty] = Types.size();
   Types.push_back(Ty);
   SC_DEBUG("  Inserting type [" << ResultSlot << "] = " << *Ty << "\n" );

   // Loop over any contained types in the definition, ensuring they are also
   // inserted.
   for (Type::subtype_iterator I = Ty->subtype_begin(), E = Ty->subtype_end();
        I != E; ++I)
     getOrCreateTypeSlot(*I);

   return ResultSlot;
 }


 void SlotCalculator::incorporateFunction(const Function *F) {
   SC_DEBUG("begin processFunction!\n");

   // Iterate over function arguments, adding them to the value table...
   for(Function::const_arg_iterator I = F->arg_begin(), E = F->arg_end();
       I != E; ++I)
     CreateFunctionValueSlot(I);

   SC_DEBUG("Inserting Instructions:\n");

   // Add all of the instructions to the type planes...
   for (Function::const_iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
     CreateFunctionValueSlot(BB);
     for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I!=E; ++I) {
       if (I->getType() != Type::VoidTy)
         CreateFunctionValueSlot(I);
     }
   }

   SC_DEBUG("end processFunction!\n");
 }

 void SlotCalculator::purgeFunction() {
   SC_DEBUG("begin purgeFunction!\n");

   // Next, remove values from existing type planes
   for (DenseMap<unsigned,unsigned,
           ModuleLevelDenseMapKeyInfo>::iterator I = ModuleLevel.begin(),
        E = ModuleLevel.end(); I != E; ++I) {
     unsigned PlaneNo = I->first;
     unsigned ModuleLev = I->second;

     // Pop all function-local values in this type-plane off of Table.
     TypePlane &Plane = getPlane(PlaneNo);
     assert(ModuleLev < Plane.size() && "module levels higher than elements?");
     for (unsigned i = ModuleLev, e = Plane.size(); i != e; ++i) {
       NodeMap.erase(Plane.back());       // Erase from nodemap
       Plane.pop_back();                  // Shrink plane
     }
   }

   ModuleLevel.clear();

   // Finally, remove any type planes defined by the function...
   while (Table.size() > NumModuleTypes) {
     TypePlane &Plane = Table.back();
     SC_DEBUG("Removing Plane " << (Table.size()-1) << " of size "
              << Plane.size() << "\n");
     for (unsigned i = 0, e = Plane.size(); i != e; ++i)
       NodeMap.erase(Plane[i]);   // Erase from nodemap

     Table.pop_back();                // Nuke the plane, we don't like it.
   }

   SC_DEBUG("end purgeFunction!\n");
 }

 inline static bool hasImplicitNull(const Type* Ty) {
   return Ty != Type::LabelTy && Ty != Type::VoidTy && !isa<OpaqueType>(Ty);
 }

 void SlotCalculator::CreateFunctionValueSlot(const Value *V) {
   assert(!NodeMap.count(V) && "Function-local value can't be inserted!");

   const Type *Ty = V->getType();
   assert(Ty != Type::VoidTy && "Can't insert void values!");
   assert(!isa<Constant>(V) && "Not a function-local value!");

   unsigned TyPlane = getOrCreateTypeSlot(Ty);
   if (Table.size() <= TyPlane)    // Make sure we have the type plane allocated.
     Table.resize(TyPlane+1, TypePlane());

   // If this is the first value noticed of this type within this function,
   // remember the module level for this type plane in ModuleLevel.  This reminds
   // us to remove the values in purgeFunction and tells us how many to remove.
   if (TyPlane < NumModuleTypes)
     ModuleLevel.insert(std::make_pair(TyPlane, Table[TyPlane].size()));

   // If this is the first value to get inserted into the type plane, make sure
   // to insert the implicit null value.
   if (Table[TyPlane].empty()) {
     // Label's and opaque types can't have a null value.
     if (hasImplicitNull(Ty)) {
       Value *ZeroInitializer = Constant::getNullValue(Ty);

       // If we are pushing zeroinit, it will be handled below.
       if (V != ZeroInitializer) {
         Table[TyPlane].push_back(ZeroInitializer);
         NodeMap[ZeroInitializer] = 0;
       }
     }
   }

   // Insert node into table and NodeMap...
   NodeMap[V] = Table[TyPlane].size();
   Table[TyPlane].push_back(V);

   SC_DEBUG("  Inserting value [" << TyPlane << "] = " << *V << " slot=" <<
            NodeMap[V] << "\n");
 }
	//===-- SlotCalculator.cpp - Calculate what slots values land in ----------===//
	//
	// The LLVM Compiler Infrastructure
	//
	// This file was developed by the LLVM research group and is distributed under
	// the University of Illinois Open Source License. See LICENSE.TXT for details.
	//
	//===----------------------------------------------------------------------===//
	//
	// This file implements a useful analysis step to figure out what numbered slots
	// values in a program will land in (keeping track of per plane information).
	//
	// This is used when writing a file to disk, either in bytecode or assembly.
	//
	//===----------------------------------------------------------------------===//

	#include "SlotCalculator.h"
	#include "llvm/Constants.h"
	#include "llvm/DerivedTypes.h"
	#include "llvm/Function.h"
	#include "llvm/InlineAsm.h"
	#include "llvm/Instructions.h"
	#include "llvm/Module.h"
	#include "llvm/TypeSymbolTable.h"
	#include "llvm/Type.h"
	#include "llvm/ValueSymbolTable.h"
	#include "llvm/ADT/STLExtras.h"
	#include <algorithm>
	#include <functional>
	using namespace llvm;

	#ifndef NDEBUG
	#include "llvm/Support/Streams.h"
	#include "llvm/Support/CommandLine.h"
	static cl::opt<bool> SlotCalculatorDebugOption("scdebug",cl::init(false),
	cl::desc("Enable SlotCalculator debug output"), cl::Hidden);
	#define SC_DEBUG(X) if (SlotCalculatorDebugOption) cerr << X
	#else
	#define SC_DEBUG(X)
	#endif

	void SlotCalculator::insertPrimitives() {
	// Preload the table with the built-in types. These built-in types are
	// inserted first to ensure that they have low integer indices which helps to
	// keep bytecode sizes small. Note that the first group of indices must match
	// the Type::TypeIDs for the primitive types. After that the integer types are
	// added, but the order and value is not critical. What is critical is that
	// the indices of these "well known" slot numbers be properly maintained in
	// Reader.h which uses them directly to extract values of these types.
	SC_DEBUG("Inserting primitive types:\n");
	// See WellKnownTypeSlots in Reader.h
	getOrCreateTypeSlot(Type::VoidTy ); // 0: VoidTySlot
	getOrCreateTypeSlot(Type::FloatTy ); // 1: FloatTySlot
	getOrCreateTypeSlot(Type::DoubleTy); // 2: DoubleTySlot
	getOrCreateTypeSlot(Type::LabelTy ); // 3: LabelTySlot
	assert(TypeMap.size() == Type::FirstDerivedTyID &&"Invalid primitive insert");
	// Above here must correspond 1:1 with the primitive types.
	getOrCreateTypeSlot(Type::Int1Ty ); // 4: Int1TySlot
	getOrCreateTypeSlot(Type::Int8Ty ); // 5: Int8TySlot
	getOrCreateTypeSlot(Type::Int16Ty ); // 6: Int16TySlot
	getOrCreateTypeSlot(Type::Int32Ty ); // 7: Int32TySlot
	getOrCreateTypeSlot(Type::Int64Ty ); // 8: Int64TySlot
	}

	SlotCalculator::SlotCalculator(const Module *M) {
	assert(M);
	TheModule = M;

	insertPrimitives();
	processModule();
	}

	// processModule - Process all of the module level function declarations and
	// types that are available.
	//
	void SlotCalculator::processModule() {
	SC_DEBUG("begin processModule!\n");

	// Add all of the global variables to the value table...
	//
	for (Module::const_global_iterator I = TheModule->global_begin(),
	E = TheModule->global_end(); I != E; ++I)
	CreateSlotIfNeeded(I);

	// Scavenge the types out of the functions, then add the functions themselves
	// to the value table...
	//
	for (Module::const_iterator I = TheModule->begin(), E = TheModule->end();
	I != E; ++I)
	CreateSlotIfNeeded(I);

	// Add all of the module level constants used as initializers
	//
	for (Module::const_global_iterator I = TheModule->global_begin(),
	E = TheModule->global_end(); I != E; ++I)
	if (I->hasInitializer())
	CreateSlotIfNeeded(I->getInitializer());

	// Now that all global constants have been added, rearrange constant planes
	// that contain constant strings so that the strings occur at the start of the
	// plane, not somewhere in the middle.
	//
	for (unsigned plane = 0, e = Table.size(); plane != e; ++plane) {
	if (const ArrayType *AT = dyn_cast<ArrayType>(Types[plane]))
	if (AT->getElementType() == Type::Int8Ty) {
	TypePlane &Plane = Table[plane];
	unsigned FirstNonStringID = 0;
	for (unsigned i = 0, e = Plane.size(); i != e; ++i)
	if (isa<ConstantAggregateZero>(Plane[i]) \|\|
	(isa<ConstantArray>(Plane[i]) &&
	cast<ConstantArray>(Plane[i])->isString())) {
	// Check to see if we have to shuffle this string around. If not,
	// don't do anything.
	if (i != FirstNonStringID) {
	// Swap the plane entries....
	std::swap(Plane[i], Plane[FirstNonStringID]);

	// Keep the NodeMap up to date.
	NodeMap[Plane[i]] = i;
	NodeMap[Plane[FirstNonStringID]] = FirstNonStringID;
	}
	++FirstNonStringID;
	}
	}
	}

	// Scan all of the functions for their constants, which allows us to emit
	// more compact modules.
	SC_DEBUG("Inserting function constants:\n");
	for (Module::const_iterator F = TheModule->begin(), E = TheModule->end();
	F != E; ++F) {
	for (Function::const_iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
	for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I!=E;++I){
	for (User::const_op_iterator OI = I->op_begin(), E = I->op_end();
	OI != E; ++OI) {
	if ((isa<Constant>(OI) && !isa<GlobalValue>(OI)) \|\|
	isa<InlineAsm>(*OI))
	CreateSlotIfNeeded(*OI);
	}
	getOrCreateTypeSlot(I->getType());
	}
	}

	// Insert constants that are named at module level into the slot pool so that
	// the module symbol table can refer to them...
	SC_DEBUG("Inserting SymbolTable values:\n");
	processTypeSymbolTable(&TheModule->getTypeSymbolTable());
	processValueSymbolTable(&TheModule->getValueSymbolTable());

	// Now that we have collected together all of the information relevant to the
	// module, compactify the type table if it is particularly big and outputting
	// a bytecode file. The basic problem we run into is that some programs have
	// a large number of types, which causes the type field to overflow its size,
	// which causes instructions to explode in size (particularly call
	// instructions). To avoid this behavior, we "sort" the type table so that
	// all non-value types are pushed to the end of the type table, giving nice
	// low numbers to the types that can be used by instructions, thus reducing
	// the amount of explodage we suffer.
	if (Types.size() >= 64) {
	unsigned FirstNonValueTypeID = 0;
	for (unsigned i = 0, e = Types.size(); i != e; ++i)
	if (Types[i]->isFirstClassType() \|\| Types[i]->isPrimitiveType()) {
	// Check to see if we have to shuffle this type around. If not, don't
	// do anything.
	if (i != FirstNonValueTypeID) {
	// Swap the type ID's.
	std::swap(Types[i], Types[FirstNonValueTypeID]);

	// Keep the TypeMap up to date.
	TypeMap[Types[i]] = i;
	TypeMap[Types[FirstNonValueTypeID]] = FirstNonValueTypeID;

	// When we move a type, make sure to move its value plane as needed.
	if (Table.size() > FirstNonValueTypeID) {
	if (Table.size() <= i) Table.resize(i+1);
	std::swap(Table[i], Table[FirstNonValueTypeID]);
	}
	}
	++FirstNonValueTypeID;
	}
	}

	NumModuleTypes = getNumPlanes();

	SC_DEBUG("end processModule!\n");
	}

	// processTypeSymbolTable - Insert all of the type sin the specified symbol
	// table.
	void SlotCalculator::processTypeSymbolTable(const TypeSymbolTable *TST) {
	for (TypeSymbolTable::const_iterator TI = TST->begin(), TE = TST->end();
	TI != TE; ++TI )
	getOrCreateTypeSlot(TI->second);
	}

	// processSymbolTable - Insert all of the values in the specified symbol table
	// into the values table...
	//
	void SlotCalculator::processValueSymbolTable(const ValueSymbolTable *VST) {
	for (ValueSymbolTable::const_iterator VI = VST->begin(), VE = VST->end();
	VI != VE; ++VI)
	CreateSlotIfNeeded(VI->getValue());
	}

	void SlotCalculator::CreateSlotIfNeeded(const Value *V) {
	// Check to see if it's already in!
	if (NodeMap.count(V)) return;

	const Type *Ty = V->getType();
	assert(Ty != Type::VoidTy && "Can't insert void values!");

	if (const Constant *C = dyn_cast<Constant>(V)) {
	if (isa<GlobalValue>(C)) {
	// Initializers for globals are handled explicitly elsewhere.
	} else if (isa<ConstantArray>(C) && cast<ConstantArray>(C)->isString()) {
	// Do not index the characters that make up constant strings. We emit
	// constant strings as special entities that don't require their
	// individual characters to be emitted.
	if (!C->isNullValue())
	ConstantStrings.push_back(cast<ConstantArray>(C));
	} else {
	// This makes sure that if a constant has uses (for example an array of
	// const ints), that they are inserted also.
	for (User::const_op_iterator I = C->op_begin(), E = C->op_end();
	I != E; ++I)
	CreateSlotIfNeeded(*I);
	}
	}

	unsigned TyPlane = getOrCreateTypeSlot(Ty);
	if (Table.size() <= TyPlane) // Make sure we have the type plane allocated.
	Table.resize(TyPlane+1, TypePlane());

	// If this is the first value to get inserted into the type plane, make sure
	// to insert the implicit null value.
	if (Table[TyPlane].empty()) {
	// Label's and opaque types can't have a null value.
	if (Ty != Type::LabelTy && !isa<OpaqueType>(Ty)) {
	Value *ZeroInitializer = Constant::getNullValue(Ty);

	// If we are pushing zeroinit, it will be handled below.
	if (V != ZeroInitializer) {
	Table[TyPlane].push_back(ZeroInitializer);
	NodeMap[ZeroInitializer] = 0;
	}
	}
	}

	// Insert node into table and NodeMap...
	NodeMap[V] = Table[TyPlane].size();
	Table[TyPlane].push_back(V);

	SC_DEBUG(" Inserting value [" << TyPlane << "] = " << *V << " slot=" <<
	NodeMap[V] << "\n");
	}


	unsigned SlotCalculator::getOrCreateTypeSlot(const Type *Ty) {
	TypeMapType::iterator TyIt = TypeMap.find(Ty);
	if (TyIt != TypeMap.end()) return TyIt->second;

	// Insert into TypeMap.
	unsigned ResultSlot = TypeMap[Ty] = Types.size();
	Types.push_back(Ty);
	SC_DEBUG(" Inserting type [" << ResultSlot << "] = " << *Ty << "\n" );

	// Loop over any contained types in the definition, ensuring they are also
	// inserted.
	for (Type::subtype_iterator I = Ty->subtype_begin(), E = Ty->subtype_end();
	I != E; ++I)
	getOrCreateTypeSlot(*I);

	return ResultSlot;
	}



	void SlotCalculator::incorporateFunction(const Function *F) {
	SC_DEBUG("begin processFunction!\n");

	// Iterate over function arguments, adding them to the value table...
	for(Function::const_arg_iterator I = F->arg_begin(), E = F->arg_end();
	I != E; ++I)
	CreateFunctionValueSlot(I);

	SC_DEBUG("Inserting Instructions:\n");

	// Add all of the instructions to the type planes...
	for (Function::const_iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
	CreateFunctionValueSlot(BB);
	for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I!=E; ++I) {
	if (I->getType() != Type::VoidTy)
	CreateFunctionValueSlot(I);
	}
	}

	SC_DEBUG("end processFunction!\n");
	}

	void SlotCalculator::purgeFunction() {
	SC_DEBUG("begin purgeFunction!\n");

	// Next, remove values from existing type planes
	for (DenseMap<unsigned,unsigned,
	ModuleLevelDenseMapKeyInfo>::iterator I = ModuleLevel.begin(),
	E = ModuleLevel.end(); I != E; ++I) {
	unsigned PlaneNo = I->first;
	unsigned ModuleLev = I->second;

	// Pop all function-local values in this type-plane off of Table.
	TypePlane &Plane = getPlane(PlaneNo);
	assert(ModuleLev < Plane.size() && "module levels higher than elements?");
	for (unsigned i = ModuleLev, e = Plane.size(); i != e; ++i) {
	NodeMap.erase(Plane.back()); // Erase from nodemap
	Plane.pop_back(); // Shrink plane
	}
	}

	ModuleLevel.clear();

	// Finally, remove any type planes defined by the function...
	while (Table.size() > NumModuleTypes) {
	TypePlane &Plane = Table.back();
	SC_DEBUG("Removing Plane " << (Table.size()-1) << " of size "
	<< Plane.size() << "\n");
	for (unsigned i = 0, e = Plane.size(); i != e; ++i)
	NodeMap.erase(Plane[i]); // Erase from nodemap

	Table.pop_back(); // Nuke the plane, we don't like it.
	}

	SC_DEBUG("end purgeFunction!\n");
	}

	inline static bool hasImplicitNull(const Type* Ty) {
	return Ty != Type::LabelTy && Ty != Type::VoidTy && !isa<OpaqueType>(Ty);
	}

	void SlotCalculator::CreateFunctionValueSlot(const Value *V) {
	assert(!NodeMap.count(V) && "Function-local value can't be inserted!");

	const Type *Ty = V->getType();
	assert(Ty != Type::VoidTy && "Can't insert void values!");
	assert(!isa<Constant>(V) && "Not a function-local value!");

	unsigned TyPlane = getOrCreateTypeSlot(Ty);
	if (Table.size() <= TyPlane) // Make sure we have the type plane allocated.
	Table.resize(TyPlane+1, TypePlane());

	// If this is the first value noticed of this type within this function,
	// remember the module level for this type plane in ModuleLevel. This reminds
	// us to remove the values in purgeFunction and tells us how many to remove.
	if (TyPlane < NumModuleTypes)
	ModuleLevel.insert(std::make_pair(TyPlane, Table[TyPlane].size()));

	// If this is the first value to get inserted into the type plane, make sure
	// to insert the implicit null value.
	if (Table[TyPlane].empty()) {
	// Label's and opaque types can't have a null value.
	if (hasImplicitNull(Ty)) {
	Value *ZeroInitializer = Constant::getNullValue(Ty);

	// If we are pushing zeroinit, it will be handled below.
	if (V != ZeroInitializer) {
	Table[TyPlane].push_back(ZeroInitializer);
	NodeMap[ZeroInitializer] = 0;
	}
	}
	}

	// Insert node into table and NodeMap...
	NodeMap[V] = Table[TyPlane].size();
	Table[TyPlane].push_back(V);

	SC_DEBUG(" Inserting value [" << TyPlane << "] = " << *V << " slot=" <<
	NodeMap[V] << "\n");
	}