[llvm-commits] CVS: llvm/lib/Bytecode/Writer/SlotCalculator.cpp

[Reid Spencer]

Changes in directory llvm/lib/Bytecode/Writer:

SlotCalculator.cpp updated: 1.108 -> 1.109
---
Log message:

For PR1194: http://llvm.org/PR1194 :
The bcreader counts on "primitive" types being inserted before they are 
referenced in other types. With recent changes to the bcwriter, this fact
became exposed since IntegerType is no longer "primitive". We can no longer 
count on all IntegerTypes being inserted early. This patch modifies 
getOrCreateTypeSlot to insert any sub-type that can't possibly recurse
before we create the slot for the type. This has the benefit of reducing
the number of OpaqueType objects the reader needs to deal with.


---
Diffs of the changes:  (+67 -5)

 SlotCalculator.cpp |   72 +++++++++++++++++++++++++++++++++++++++++++++++++----
 1 files changed, 67 insertions(+), 5 deletions(-)


Index: llvm/lib/Bytecode/Writer/SlotCalculator.cpp
diff -u llvm/lib/Bytecode/Writer/SlotCalculator.cpp:1.108 llvm/lib/Bytecode/Writer/SlotCalculator.cpp:1.109
--- llvm/lib/Bytecode/Writer/SlotCalculator.cpp:1.108	Sat Feb 10 05:59:10 2007
+++ llvm/lib/Bytecode/Writer/SlotCalculator.cpp	Sat Feb 10 08:04:08 2007
@@ -259,14 +259,77 @@
   TypeMapType::iterator TyIt = TypeMap.find(Ty);
   if (TyIt != TypeMap.end()) return TyIt->second;
 
-  // Insert into TypeMap.
+  // Try to reduce the number of opaque types the reader has to process by 
+  // first inserting any contained types that can't possibly recurse back to 
+  // this type. Making those types concrete before creating the slot number for
+  // this type means the reader will not have to create OpaqueTy placeholders
+  // for the this type's sub-types.  If the sub-type is a pointer, function
+  // type, structure with pointer/array/struct, or an array with a pointer
+  // element type, then we defer it. Otherwise, we can either ignore the 
+  // primitive types (avoid recursion) or create the slot up front.
+  // Note that this is a trade-off. It slows writing (very slightly) but makes
+  // reading a little faster, especially for large complex types.
+  typedef SmallVector<const Type*, 16> DeferVecType;
+  DeferVecType DeferList;
+  for (Type::subtype_iterator I = Ty->subtype_begin(), E = Ty->subtype_end();
+       I != E; ++I)
+    switch ((*I)->getTypeID()) {
+      default: assert(0 && "Invalid TypeID?");
+      case Type::VoidTyID:
+      case Type::FloatTyID:
+      case Type::DoubleTyID:
+      case Type::LabelTyID:
+        // These are all primitive and have been inserted already, just ignore
+        // to avoid the recursion.
+        break;
+      case Type::FunctionTyID:
+      case Type::PointerTyID:
+        // Pointers and Functions can recurse to us, defer it.
+        DeferList.push_back(*I);
+        break;
+      case Type::StructTyID:
+      case Type::PackedStructTyID: {
+        // if any of the fields of the structure are pointers, structures or
+        // arrays with pointer element type, defer it.
+        const StructType *Ty = &cast<StructType>(*(*I));
+        Type::subtype_iterator EI = Ty->subtype_begin();
+        Type::subtype_iterator EE = Ty->subtype_end();
+        for ( ; EI != EE; ++EI) {
+          const Type* SubTy = *EI;
+          if (isa<PointerType>(SubTy) || isa<StructType>(SubTy) || 
+              (isa<ArrayType>(SubTy) && 
+               isa<PointerType>(cast<ArrayType>(SubTy)->getElementType())))
+            break;
+        }
+        if (EI != EE)
+          DeferList.push_back(*I);
+        else
+          getOrCreateTypeSlot(*I);
+        break;
+      }
+      case Type::ArrayTyID:  {
+        const ArrayType* ArrayTy = &cast<ArrayType>(*(*I));
+        if (isa<PointerType>(ArrayTy->getElementType())) {
+          // this might recurse to us, defer it.
+          DeferList.push_back(*I);
+          break;
+        }
+        /* FALL THROUGH (others are okay) */
+      }
+      case Type::OpaqueTyID:  // no elements
+      case Type::IntegerTyID: // no elements
+      case Type::PackedTyID:  // can only have elements of non-recursing types
+        getOrCreateTypeSlot(*I);
+        break;
+    }
+
+  // Now we must create the slot for this type by inserting 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();
+  // Finally, process any deferred sub-types and create their slots.
+  for (DeferVecType::iterator I = DeferList.begin(), E = DeferList.end();
        I != E; ++I)
     getOrCreateTypeSlot(*I);
 
@@ -274,7 +337,6 @@
 }
 
 
-
 void SlotCalculator::incorporateFunction(const Function *F) {
   SC_DEBUG("begin processFunction!\n");