1 files changed, 91 insertions, 0 deletions
diff --git a/lib/Transforms/TransformInternals.cpp b/lib/Transforms/TransformInternals.cpp
new file mode 100644
index 0000000000..8cd2511e7c
--- /dev/null
+++ b/lib/Transforms/TransformInternals.cpp
@@ -0,0 +1,91 @@
+//===- TransformInternals.cpp - Implement shared functions for transforms -===//
+//
+//                     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 defines shared functions used by the different components of the
+//  Transforms library.
+//
+//===----------------------------------------------------------------------===//
+
+#include "TransformInternals.h"
+#include "llvm/Type.h"
+#include "llvm/Function.h"
+#include "llvm/Instructions.h"
+using namespace llvm;
+
+static const Type *getStructOffsetStep(const StructType *STy, uint64_t &Offset,
+                                       std::vector<Value*> &Indices,
+                                       const TargetData &TD) {
+  assert(Offset < TD.getTypeSize(STy) && "Offset not in composite!");
+  const StructLayout *SL = TD.getStructLayout(STy);
+
+  // This loop terminates always on a 0 <= i < MemberOffsets.size()
+  unsigned i;
+  for (i = 0; i < SL->MemberOffsets.size()-1; ++i)
+    if (Offset >= SL->MemberOffsets[i] && Offset < SL->MemberOffsets[i+1])
+      break;
+
+  assert(Offset >= SL->MemberOffsets[i] &&
+         (i == SL->MemberOffsets.size()-1 || Offset < SL->MemberOffsets[i+1]));
+
+  // Make sure to save the current index...
+  Indices.push_back(ConstantUInt::get(Type::UIntTy, i));
+  Offset = SL->MemberOffsets[i];
+  return STy->getContainedType(i);
+}
+
+
+// getStructOffsetType - Return a vector of offsets that are to be used to index
+// into the specified struct type to get as close as possible to index as we
+// can.  Note that it is possible that we cannot get exactly to Offset, in which
+// case we update offset to be the offset we actually obtained.  The resultant
+// leaf type is returned.
+//
+// If StopEarly is set to true (the default), the first object with the
+// specified type is returned, even if it is a struct type itself.  In this
+// case, this routine will not drill down to the leaf type.  Set StopEarly to
+// false if you want a leaf
+//
+const Type *llvm::getStructOffsetType(const Type *Ty, unsigned &Offset,
+                                      std::vector<Value*> &Indices,
+                                      const TargetData &TD, bool StopEarly) {
+  if (Offset == 0 && StopEarly && !Indices.empty())
+    return Ty;    // Return the leaf type
+
+  uint64_t ThisOffset;
+  const Type *NextType;
+  if (const StructType *STy = dyn_cast<StructType>(Ty)) {
+    if (STy->getNumElements()) {
+      Offset = 0;
+      return STy;
+    }
+
+    ThisOffset = Offset;
+    NextType = getStructOffsetStep(STy, ThisOffset, Indices, TD);
+  } else if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
+    assert(Offset == 0 || Offset < TD.getTypeSize(ATy) &&
+           "Offset not in composite!");
+
+    NextType = ATy->getElementType();
+    unsigned ChildSize = (unsigned)TD.getTypeSize(NextType);
+    if (ConstantSInt::isValueValidForType(Type::IntTy, Offset/ChildSize))
+      Indices.push_back(ConstantSInt::get(Type::IntTy, Offset/ChildSize));
+    else
+      Indices.push_back(ConstantSInt::get(Type::LongTy, Offset/ChildSize));
+    ThisOffset = (Offset/ChildSize)*ChildSize;
+  } else {
+    Offset = 0;   // Return the offset that we were able to achieve
+    return Ty;    // Return the leaf type
+  }
+
+  unsigned SubOffs = unsigned(Offset - ThisOffset);
+  const Type *LeafTy = getStructOffsetType(NextType, SubOffs,
+                                           Indices, TD, StopEarly);
+  Offset = unsigned(ThisOffset + SubOffs);
+  return LeafTy;
+}