1 files changed, 95 insertions, 0 deletions
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGAddressAnalysis.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGAddressAnalysis.cpp
new file mode 100644
index 0000000000000..d2e0dbbf88ecd
--- /dev/null
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGAddressAnalysis.cpp
@@ -0,0 +1,95 @@
+//===-- llvm/CodeGen/SelectionDAGAddressAnalysis.cpp ------- DAG Address
+//Analysis ---*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+
+#include "llvm/CodeGen/SelectionDAGAddressAnalysis.h"
+#include "llvm/CodeGen/ISDOpcodes.h"
+#include "llvm/CodeGen/SelectionDAG.h"
+#include "llvm/CodeGen/SelectionDAGNodes.h"
+
+namespace llvm {
+
+bool BaseIndexOffset::equalBaseIndex(BaseIndexOffset &Other,
+                                     const SelectionDAG &DAG, int64_t &Off) {
+  // Obvious equivalent
+  Off = Other.Offset - Offset;
+  if (Other.Base == Base && Other.Index == Index &&
+      Other.IsIndexSignExt == IsIndexSignExt)
+    return true;
+
+  // Match GlobalAddresses
+  if (Index == Other.Index)
+    if (GlobalAddressSDNode *A = dyn_cast<GlobalAddressSDNode>(Base))
+      if (GlobalAddressSDNode *B = dyn_cast<GlobalAddressSDNode>(Other.Base))
+        if (A->getGlobal() == B->getGlobal()) {
+          Off += B->getOffset() - A->getOffset();
+          return true;
+        }
+
+  // TODO: we should be able to add FrameIndex analysis improvements here.
+
+  return false;
+}
+
+/// Parses tree in Ptr for base, index, offset addresses.
+BaseIndexOffset BaseIndexOffset::match(SDValue Ptr) {
+  // (((B + I*M) + c)) + c ...
+  SDValue Base = Ptr;
+  SDValue Index = SDValue();
+  int64_t Offset = 0;
+  bool IsIndexSignExt = false;
+
+  // Consume constant adds
+  while (Base->getOpcode() == ISD::ADD &&
+         isa<ConstantSDNode>(Base->getOperand(1))) {
+    int64_t POffset = cast<ConstantSDNode>(Base->getOperand(1))->getSExtValue();
+    Offset += POffset;
+    Base = Base->getOperand(0);
+  }
+
+  if (Base->getOpcode() == ISD::ADD) {
+    // TODO: The following code appears to be needless as it just
+    //       bails on some Ptrs early, reducing the cases where we
+    //       find equivalence. We should be able to remove this.
+    // Inside a loop the current BASE pointer is calculated using an ADD and a
+    // MUL instruction. In this case Base is the actual BASE pointer.
+    // (i64 add (i64 %array_ptr)
+    //          (i64 mul (i64 %induction_var)
+    //                   (i64 %element_size)))
+    if (Base->getOperand(1)->getOpcode() == ISD::MUL)
+      return BaseIndexOffset(Base, Index, Offset, IsIndexSignExt);
+
+    // Look at Base + Index + Offset cases.
+    Index = Base->getOperand(1);
+    SDValue PotentialBase = Base->getOperand(0);
+
+    // Skip signextends.
+    if (Index->getOpcode() == ISD::SIGN_EXTEND) {
+      Index = Index->getOperand(0);
+      IsIndexSignExt = true;
+    }
+
+    // Check if Index Offset pattern
+    if (Index->getOpcode() != ISD::ADD ||
+        !isa<ConstantSDNode>(Index->getOperand(1)))
+      return BaseIndexOffset(PotentialBase, Index, Offset, IsIndexSignExt);
+
+    Offset += cast<ConstantSDNode>(Index->getOperand(1))->getSExtValue();
+    Index = Index->getOperand(0);
+    if (Index->getOpcode() == ISD::SIGN_EXTEND) {
+      Index = Index->getOperand(0);
+      IsIndexSignExt = true;
+    } else
+      IsIndexSignExt = false;
+    Base = PotentialBase;
+  }
+  return BaseIndexOffset(Base, Index, Offset, IsIndexSignExt);
+}
+} // end namespace llvm