Initial support for writing bitcode files. This currently only writes types,

the type symtab, and global/function protos, and is missing the important
size optimization, but it is a place to start.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@36331 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Bitcode/Writer/ValueEnumerator.cpp

@@ -0,0 +1,235 @@
+//===-- ValueEnumerator.cpp - Number values and types for bitcode writer --===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by Chris Lattner and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the ValueEnumerator class.
+//
+//===----------------------------------------------------------------------===//
+
+#include "ValueEnumerator.h"
+#include "llvm/Module.h"
+#include "llvm/TypeSymbolTable.h"
+#include "llvm/ValueSymbolTable.h"
+using namespace llvm;
+
+/// ValueEnumerator - Enumerate module-level information.
+ValueEnumerator::ValueEnumerator(const Module *M) {
+  // Enumerate the global variables.
+  for (Module::const_global_iterator I = M->global_begin(),
+         E = M->global_end(); I != E; ++I)
+    EnumerateValue(I);
+
+  // Enumerate the functions.
+  for (Module::const_iterator I = M->begin(), E = M->end(); I != E; ++I)
+    EnumerateValue(I);
+
+  // Enumerate the global variable initializers.
+  for (Module::const_global_iterator I = M->global_begin(),
+         E = M->global_end(); I != E; ++I)
+    if (I->hasInitializer())
+      EnumerateValue(I->getInitializer());
+
+  // FIXME: Implement the 'string constant' optimization.
+
+  // Enumerate types used by the type symbol table.
+  EnumerateTypeSymbolTable(M->getTypeSymbolTable());
+
+  // Insert constants that are named at module level into the slot pool so that
+  // the module symbol table can refer to them...
+  EnumerateValueSymbolTable(M->getValueSymbolTable());
+  
+  // Enumerate types used by function bodies.
+  for (Module::const_iterator F = M->begin(), E = M->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)
+          EnumerateType((*OI)->getType());
+        EnumerateType(I->getType());
+      }
+  }
+    
+  
+  // FIXME: std::partition the type and value tables so that first-class types
+  // come earlier than aggregates.
+  
+  // FIXME: Sort type/value tables by frequency.
+}
+
+/// EnumerateTypeSymbolTable - Insert all of the types in the specified symbol
+/// table.
+void ValueEnumerator::EnumerateTypeSymbolTable(const TypeSymbolTable &TST) {
+  for (TypeSymbolTable::const_iterator TI = TST.begin(), TE = TST.end(); 
+       TI != TE; ++TI)
+    EnumerateType(TI->second);
+}
+
+/// EnumerateValueSymbolTable - Insert all of the values in the specified symbol
+/// table into the values table.
+void ValueEnumerator::EnumerateValueSymbolTable(const ValueSymbolTable &VST) {
+  for (ValueSymbolTable::const_iterator VI = VST.begin(), VE = VST.end(); 
+       VI != VE; ++VI)
+    EnumerateValue(VI->getValue());
+}
+
+void ValueEnumerator::EnumerateValue(const Value *V) {
+  assert(V->getType() != Type::VoidTy && "Can't insert void values!");
+  
+  // Check to see if it's already in!
+  unsigned &ValueID = ValueMap[V];
+  if (ValueID) {
+    // Increment use count.
+    Values[ValueID-1].second++;
+    return;
+  }
+  
+  // Add the value.
+  Values.push_back(std::make_pair(V, 1U));
+  ValueID = Values.size();
+
+  if (const Constant *C = dyn_cast<Constant>(V)) {
+    if (isa<GlobalValue>(C)) {
+      // Initializers for globals are handled explicitly elsewhere.
+    } 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)
+        EnumerateValue(*I);
+    }
+  }
+
+  EnumerateType(V->getType());
+}
+
+
+void ValueEnumerator::EnumerateType(const Type *Ty) {
+  unsigned &TypeID = TypeMap[Ty];
+  
+  if (TypeID) {
+    // If we've already seen this type, just increase its occurrence count.
+    Types[TypeID-1].second++;
+    return;
+  }
+  
+  // First time we saw this type, add it.
+  Types.push_back(std::make_pair(Ty, 1U));
+  TypeID = Types.size();
+  
+  // Enumerate subtypes.
+  for (Type::subtype_iterator I = Ty->subtype_begin(), E = Ty->subtype_end();
+       I != E; ++I)
+    EnumerateType(*I);
+}
+
+
+
+#if 0
+
+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");
+}
+
+#endif