Initial checkin of gep_type_begin/end which will be used to address PR82

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@10212 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Support/GetElementPtrTypeIterator.h

@@ -0,0 +1,92 @@
+//===- llvm/Support/GetElementPtrTypeIterator.h -----------------*- C++ -*-===//
+// 
+//                     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 an iterator for walking through the types indexed by
+// getelementptr instructions.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_GETELEMENTPTRTYPE_H
+#define LLVM_SUPPORT_GETELEMENTPTRTYPE_H
+
+#include "Support/iterator"
+#include "llvm/iMemory.h"
+#include "llvm/DerivedTypes.h"
+
+namespace llvm {
+  class GetElementPtrTypeIterator
+    : public forward_iterator<const Type *, ptrdiff_t> {
+    typedef forward_iterator<const Type*, ptrdiff_t> super;
+
+    GetElementPtrInst *TheGEP;
+    const Type *CurTy;
+    unsigned Operand;
+    
+    GetElementPtrTypeIterator() {}
+  public:
+
+    static GetElementPtrTypeIterator begin(GetElementPtrInst *gep) {
+      GetElementPtrTypeIterator I;
+      I.TheGEP = gep;
+      I.CurTy = gep->getOperand(0)->getType();
+      I.Operand = 1;
+      return I;
+    }
+    static GetElementPtrTypeIterator end(GetElementPtrInst *gep) {
+      GetElementPtrTypeIterator I;
+      I.TheGEP = gep;
+      I.CurTy = 0;
+      I.Operand = gep->getNumOperands();
+      return I;
+    }
+
+    bool operator==(const GetElementPtrTypeIterator& x) const { 
+      return Operand == x.Operand;
+    }
+    bool operator!=(const GetElementPtrTypeIterator& x) const {
+      return !operator==(x);
+    }
+
+    const Type *operator*() const { 
+      return CurTy;
+    }
+
+    // This is a non-standard operator->.  It allows you to call methods on the
+    // current type directly.
+    const Type *operator->() const { return operator*(); }
+    
+    unsigned getOperandNum() const { return Operand; }
+
+    Value *getOperand() const { return TheGEP->getOperand(Operand); }
+
+    GetElementPtrTypeIterator& operator++() {   // Preincrement
+      if (const CompositeType *CT = dyn_cast<CompositeType>(CurTy)) {
+        CurTy = CT->getTypeAtIndex(getOperand());
+      } else {
+        CurTy = 0;
+      }
+      ++Operand;
+      return *this; 
+    }
+
+    GetElementPtrTypeIterator operator++(int) { // Postincrement
+      GetElementPtrTypeIterator tmp = *this; ++*this; return tmp; 
+    }
+  };
+
+  inline GetElementPtrTypeIterator gep_type_begin(GetElementPtrInst *GEP) {
+    return GetElementPtrTypeIterator::begin(GEP);
+  }
+
+  inline GetElementPtrTypeIterator gep_type_end(GetElementPtrInst *GEP) {
+    return GetElementPtrTypeIterator::end(GEP);
+  }
+} // end namespace llvm
+
+#endif