From da7f31493ca364241fde15b34098233155055596 Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Mon, 26 Nov 2001 17:01:47 +0000
Subject: [PATCH] Implement: isLosslesslyConvertableTo and new CompositeType
 base class

llvm-svn: 1347
---
 lib/VMCore/Type.cpp | 55 +++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 53 insertions(+), 2 deletions(-)

diff --git a/lib/VMCore/Type.cpp b/lib/VMCore/Type.cpp
index ad50ce08839..53844d605d3 100644
--- a/lib/VMCore/Type.cpp
+++ b/lib/VMCore/Type.cpp
@@ -67,6 +67,57 @@ const Type *Type::getPrimitiveType(PrimitiveID IDNumber) {
   }
 }
 
+// isLosslesslyConvertableTo - Return true if this type can be converted to
+// 'Ty' without any reinterpretation of bits.  For example, uint to int.
+//
+bool Type::isLosslesslyConvertableTo(const Type *Ty) const {
+  if (this == Ty) return true;
+  if ((!isPrimitiveType() && !Ty->isPointerType()) ||
+      (!isPointerType()   && !Ty->isPrimitiveType())) return false;
+
+  if (getPrimitiveID() == Ty->getPrimitiveID())
+    return true;  // Handles identity cast, and cast of differing pointer types
+
+  // Now we know that they are two differing primitive or pointer types
+  switch (getPrimitiveID()) {
+  case Type::UByteTyID:   return Ty == Type::SByteTy;
+  case Type::SByteTyID:   return Ty == Type::UByteTy;
+  case Type::UShortTyID:  return Ty == Type::ShortTy;
+  case Type::ShortTyID:   return Ty == Type::UShortTy;
+  case Type::UIntTyID:    return Ty == Type::IntTy;
+  case Type::IntTyID:     return Ty == Type::UIntTy;
+  case Type::ULongTyID:
+  case Type::LongTyID:
+  case Type::PointerTyID:
+    return Ty == Type::ULongTy || Ty == Type::LongTy ||
+           Ty->getPrimitiveID() == Type::PointerTyID;
+  default:
+    return false;  // Other types have no identity values
+  }
+}
+
+
+bool StructType::indexValid(const Value *V) const {
+  if (!isa<ConstPoolVal>(V)) return false;
+  if (V->getType() != Type::UByteTy) return false;
+  unsigned Idx = cast<ConstPoolUInt>(V)->getValue();
+  return Idx < ETypes.size();
+}
+
+// getTypeAtIndex - Given an index value into the type, return the type of the
+// element.  For a structure type, this must be a constant value...
+//
+const Type *StructType::getTypeAtIndex(const Value *V) const {
+  assert(isa<ConstPoolVal>(V) && "Structure index must be a constant!!");
+  assert(V->getType() == Type::UByteTy && "Structure index must be ubyte!");
+  unsigned Idx = cast<ConstPoolUInt>(V)->getValue();
+  assert(Idx < ETypes.size() && "Structure index out of range!");
+  assert(indexValid(V) && "Invalid structure index!"); // Duplicate check
+
+  return ETypes[Idx];
+}
+
+
 //===----------------------------------------------------------------------===//
 //                           Auxilliary classes
 //===----------------------------------------------------------------------===//
@@ -147,13 +198,13 @@ MethodType::MethodType(const Type *Result, const vector<const Type*> &Params,
 }
 
 ArrayType::ArrayType(const Type *ElType, int NumEl)
-  : DerivedType("", ArrayTyID), ElementType(PATypeHandle<Type>(ElType, this)) {
+  : CompositeType("", ArrayTyID), ElementType(PATypeHandle<Type>(ElType, this)){
   NumElements = NumEl;
   setDerivedTypeProperties();
 }
 
 StructType::StructType(const vector<const Type*> &Types)
-  : DerivedType("", StructTyID) {
+  : CompositeType("", StructTyID) {
   ETypes.reserve(Types.size());
   for (unsigned i = 0; i < Types.size(); ++i) {
     assert(Types[i] != Type::VoidTy && "Void type in method prototype!!");