Imported Upstream version 5.18.0.246

Former-commit-id: 0c7ce5b1a7851e13f22acfd379b7f9fb304e4833

external/llvm/lib/IR/Use.cpp

@@ -0,0 +1,127 @@
+//===-- 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.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/IR/Use.h"
+#include "llvm/IR/User.h"
+#include "llvm/IR/Value.h"
+#include <new>
+
+namespace llvm {
+
+void Use::swap(Use &RHS) {
+  if (Val == RHS.Val)
+    return;
+
+  if (Val)
+    removeFromList();
+
+  Value *OldVal = Val;
+  if (RHS.Val) {
+    RHS.removeFromList();
+    Val = RHS.Val;
+    Val->addUse(*this);
+  } else {
+    Val = nullptr;
+  }
+
+  if (OldVal) {
+    RHS.Val = OldVal;
+    RHS.Val->addUse(RHS);
+  } else {
+    RHS.Val = nullptr;
+  }
+}
+
+User *Use::getUser() const {
+  const Use *End = getImpliedUser();
+  const UserRef *ref = reinterpret_cast<const UserRef *>(End);
+  return ref->getInt() ? ref->getPointer()
+                       : reinterpret_cast<User *>(const_cast<Use *>(End));
+}
+
+unsigned Use::getOperandNo() const {
+  return this - getUser()->op_begin();
+}
+
+// Sets up the waymarking algorithm's tags for a series of Uses. See the
+// algorithm details here:
+//
+//   http://www.llvm.org/docs/ProgrammersManual.html#the-waymarking-algorithm
+//
+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;
+}
+
+void Use::zap(Use *Start, const Use *Stop, bool del) {
+  while (Start != Stop)
+    (--Stop)->~Use();
+  if (del)
+    ::operator delete(Start);
+}
+
+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;
+    }
+  }
+}
+
+} // End llvm namespace