1 files changed, 145 insertions, 0 deletions
diff --git a/lib/IR/Use.cpp b/lib/IR/Use.cpp
new file mode 100644
index 0000000000..0128adc3f7
--- /dev/null
+++ b/lib/IR/Use.cpp
@@ -0,0 +1,145 @@
+//===-- Use.cpp - Implement the Use class ---------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the algorithm for finding the User of a Use.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Value.h"
+#include <new>
+
+namespace llvm {
+
+//===----------------------------------------------------------------------===//
+//                         Use swap Implementation
+//===----------------------------------------------------------------------===//
+
+void Use::swap(Use &RHS) {
+  Value *V1(Val);
+  Value *V2(RHS.Val);
+  if (V1 != V2) {
+    if (V1) {
+      removeFromList();
+    }
+
+    if (V2) {
+      RHS.removeFromList();
+      Val = V2;
+      V2->addUse(*this);
+    } else {
+      Val = 0;
+    }
+
+    if (V1) {
+      RHS.Val = V1;
+      V1->addUse(RHS);
+    } else {
+      RHS.Val = 0;
+    }
+  }
+}
+
+//===----------------------------------------------------------------------===//
+//                         Use getImpliedUser Implementation
+//===----------------------------------------------------------------------===//
+
+const Use *Use::getImpliedUser() const {
+  const Use *Current = this;
+
+  while (true) {
+    unsigned Tag = (Current++)->Prev.getInt();
+    switch (Tag) {
+      case zeroDigitTag:
+      case oneDigitTag:
+        continue;
+
+      case stopTag: {
+        ++Current;
+        ptrdiff_t Offset = 1;
+        while (true) {
+          unsigned Tag = Current->Prev.getInt();
+          switch (Tag) {
+            case zeroDigitTag:
+            case oneDigitTag:
+              ++Current;
+              Offset = (Offset << 1) + Tag;
+              continue;
+            default:
+              return Current + Offset;
+          }
+        }
+      }
+
+      case fullStopTag:
+        return Current;
+    }
+  }
+}
+
+//===----------------------------------------------------------------------===//
+//                         Use initTags Implementation
+//===----------------------------------------------------------------------===//
+
+Use *Use::initTags(Use * const Start, Use *Stop) {
+  ptrdiff_t Done = 0;
+  while (Done < 20) {
+    if (Start == Stop--)
+      return Start;
+    static const PrevPtrTag tags[20] = { fullStopTag, oneDigitTag, stopTag,
+                                         oneDigitTag, oneDigitTag, stopTag,
+                                         zeroDigitTag, oneDigitTag, oneDigitTag,
+                                         stopTag, zeroDigitTag, oneDigitTag,
+                                         zeroDigitTag, oneDigitTag, stopTag,
+                                         oneDigitTag, oneDigitTag, oneDigitTag,
+                                         oneDigitTag, stopTag
+                                       };
+    new(Stop) Use(tags[Done++]);
+  }
+
+  ptrdiff_t Count = Done;
+  while (Start != Stop) {
+    --Stop;
+    if (!Count) {
+      new(Stop) Use(stopTag);
+      ++Done;
+      Count = Done;
+    } else {
+      new(Stop) Use(PrevPtrTag(Count & 1));
+      Count >>= 1;
+      ++Done;
+    }
+  }
+
+  return Start;
+}
+
+//===----------------------------------------------------------------------===//
+//                         Use zap Implementation
+//===----------------------------------------------------------------------===//
+
+void Use::zap(Use *Start, const Use *Stop, bool del) {
+  while (Start != Stop)
+    (--Stop)->~Use();
+  if (del)
+    ::operator delete(Start);
+}
+
+//===----------------------------------------------------------------------===//
+//                         Use getUser Implementation
+//===----------------------------------------------------------------------===//
+
+User *Use::getUser() const {
+  const Use *End = getImpliedUser();
+  const UserRef *ref = reinterpret_cast<const UserRef*>(End);
+  return ref->getInt()
+    ? ref->getPointer()
+    : (User*)End;
+}
+
+} // End llvm namespace