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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@2 91177308-0d34-0410-b5e6-96231b3b80d8

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diff --git a/lib/VMCore/ConstantFolding.h b/lib/VMCore/ConstantFolding.h
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+//===-- ConstantHandling.h - Stuff for manipulating constants ----*- C++ -*--=//
+//
+// This file contains the declarations of some cool operators that allow you
+// to do natural things with constant pool values.
+//
+// Unfortunately we can't overload operators on pointer types (like this:)
+//
+//      inline bool operator==(const ConstPoolVal *V1, const ConstPoolVal *V2)
+//
+// so we must make due with references, even though it leads to some butt ugly
+// looking code downstream.  *sigh*  (ex:  ConstPoolVal *Result = *V1 + *v2; )
+//
+//===----------------------------------------------------------------------===//
+//
+// WARNING: These operators return pointers to newly 'new'd objects.  You MUST
+//          make sure to free them if you don't want them hanging around. Also,
+//          note that these may return a null object if I don't know how to 
+//          perform those operations on the specified constant types.
+//
+//===----------------------------------------------------------------------===//
+//
+// Implementation notes:
+//   This library is implemented this way for a reason: In most cases, we do
+//   not want to have to link the constant mucking code into an executable.
+//   We do, however want to tie some of this into the main type system, as an
+//   optional component.  By using a mutable cache member in the Type class, we
+//   get exactly the kind of behavior we want.
+//
+// In the end, we get performance almost exactly the same as having a virtual
+// function dispatch, but we don't have to put our virtual functions into the
+// "Type" class, and we can implement functionality with templates. Good deal.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_OPT_CONSTANTHANDLING_H
+#define LLVM_OPT_CONSTANTHANDLING_H
+
+#include "llvm/ConstPoolVals.h"
+#include "llvm/Type.h"
+
+//===----------------------------------------------------------------------===//
+//  Implement == directly...
+//===----------------------------------------------------------------------===//
+
+inline ConstPoolBool *operator==(const ConstPoolVal &V1, 
+                                 const ConstPoolVal &V2) {
+  assert(V1.getType() == V2.getType() && "Constant types must be identical!");
+  return new ConstPoolBool(V1.equals(&V2));
+}
+
+//===----------------------------------------------------------------------===//
+//  Implement all other operators indirectly through TypeRules system
+//===----------------------------------------------------------------------===//
+
+class ConstRules {
+protected:
+  inline ConstRules() {}  // Can only be subclassed...
+public:
+  // Unary Operators...
+  virtual ConstPoolVal *neg(const ConstPoolVal *V) const = 0;
+  virtual ConstPoolVal *not(const ConstPoolVal *V) const = 0;
+
+  // Binary Operators...
+  virtual ConstPoolVal *add(const ConstPoolVal *V1, 
+                            const ConstPoolVal *V2) const = 0;
+  virtual ConstPoolVal *sub(const ConstPoolVal *V1, 
+                            const ConstPoolVal *V2) const = 0;
+
+  virtual ConstPoolBool *lessthan(const ConstPoolVal *V1, 
+                                  const ConstPoolVal *V2) const = 0;
+
+  // ConstRules::get - A type will cache its own type rules if one is needed...
+  // we just want to make sure to hit the cache instead of doing it indirectly,
+  //  if possible...
+  //
+  static inline const ConstRules *get(const ConstPoolVal &V) {
+    const ConstRules *Result = V.getType()->getConstRules();
+    return Result ? Result : find(V.getType());
+  }
+private :
+  static const ConstRules *find(const Type *Ty);
+
+  ConstRules(const ConstRules &);             // Do not implement
+  ConstRules &operator=(const ConstRules &);  // Do not implement
+};
+
+
+inline ConstPoolVal *operator-(const ConstPoolVal &V) {
+  return ConstRules::get(V)->neg(&V);
+}
+
+inline ConstPoolVal *operator!(const ConstPoolVal &V) {
+  return ConstRules::get(V)->not(&V);
+}
+
+
+
+inline ConstPoolVal *operator+(const ConstPoolVal &V1, const ConstPoolVal &V2) {
+  assert(V1.getType() == V2.getType() && "Constant types must be identical!");
+  return ConstRules::get(V1)->add(&V1, &V2);
+}
+
+inline ConstPoolVal *operator-(const ConstPoolVal &V1, const ConstPoolVal &V2) {
+  assert(V1.getType() == V2.getType() && "Constant types must be identical!");
+  return ConstRules::get(V1)->sub(&V1, &V2);
+}
+
+inline ConstPoolBool *operator<(const ConstPoolVal &V1, 
+                                const ConstPoolVal &V2) {
+  assert(V1.getType() == V2.getType() && "Constant types must be identical!");
+  return ConstRules::get(V1)->lessthan(&V1, &V2);
+}
+
+
+//===----------------------------------------------------------------------===//
+//  Implement 'derived' operators based on what we already have...
+//===----------------------------------------------------------------------===//
+
+inline ConstPoolBool *operator>(const ConstPoolVal &V1, 
+                                const ConstPoolVal &V2) {
+  return V2 < V1;
+}
+
+inline ConstPoolBool *operator!=(const ConstPoolVal &V1, 
+                                 const ConstPoolVal &V2) {
+  ConstPoolBool *Result = V1 == V2;
+  Result->setValue(!Result->getValue());     // Invert value
+  return Result;     // !(V1 == V2)
+}
+
+inline ConstPoolBool *operator>=(const ConstPoolVal &V1, 
+                                 const ConstPoolVal &V2) {
+  ConstPoolBool *Result = V1 < V2;
+  Result->setValue(!Result->getValue());     // Invert value
+  return Result;      // !(V1 < V2)
+}
+
+inline ConstPoolBool *operator<=(const ConstPoolVal &V1, 
+                                 const ConstPoolVal &V2) {
+  ConstPoolBool *Result = V1 > V2;
+  Result->setValue(!Result->getValue());     // Invert value
+  return Result;      // !(V1 > V2)
+}
+
+#endif