Flag -> Glue, the ongoing saga

[oota-llvm.git] / lib / VMCore / Use.cpp

diff --git a/lib/VMCore/Use.cpp b/lib/VMCore/Use.cpp
index 0c566a9cb70aa3a25cfbe1cb6d3532b514da3227..fec710b39459b2d1cccfe9d80afcec71ab724fae 100644 (file)
--- a/lib/VMCore/Use.cpp
+++ b/lib/VMCore/Use.cpp
@@ -86,14 +86,27 @@ const Use *Use::getImpliedUser() const {
 //===----------------------------------------------------------------------===//
 
 Use *Use::initTags(Use * const Start, Use *Stop, ptrdiff_t Done) {
+  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
+                                       };
+    Stop->Prev.setFromOpaqueValue(reinterpret_cast<Use**>(tags[Done++]));
+    Stop->Val = 0;
+  }
+
   ptrdiff_t Count = Done;
   while (Start != Stop) {
     --Stop;
     Stop->Val = 0;
     if (!Count) {
-      Stop->Prev.setFromOpaqueValue(reinterpret_cast<Use**>(Done == 0
-                                                            ? fullStopTag
-                                                            : stopTag));
+      Stop->Prev.setFromOpaqueValue(reinterpret_cast<Use**>(stopTag));
       ++Done;
       Count = Done;
     } else {
@@ -128,7 +141,7 @@ void Use::zap(Use *Start, const Use *Stop, bool del) {
 //                         AugmentedUse layout struct
 //===----------------------------------------------------------------------===//
 
-struct AugmentedUse : Use {
+struct AugmentedUse : public Use {
   PointerIntPair<User*, 1, Tag> ref;
   AugmentedUse(); // not implemented
 };
@@ -163,4 +176,71 @@ Use *User::allocHungoffUses(unsigned N) const {
   return Use::initTags(Begin, End);
 }
 
+//===----------------------------------------------------------------------===//
+//                         User operator new Implementations
+//===----------------------------------------------------------------------===//
+
+void *User::operator new(size_t s, unsigned Us) {
+  void *Storage = ::operator new(s + sizeof(Use) * Us);
+  Use *Start = static_cast<Use*>(Storage);
+  Use *End = Start + Us;
+  User *Obj = reinterpret_cast<User*>(End);
+  Obj->OperandList = Start;
+  Obj->NumOperands = Us;
+  Use::initTags(Start, End);
+  return Obj;
+}
+
+/// Prefixed allocation - just before the first Use, allocate a NULL pointer.
+/// The destructor can detect its presence and readjust the OperandList
+/// for deletition.
+///
+void *User::operator new(size_t s, unsigned Us, bool Prefix) {
+  // currently prefixed allocation only admissible for
+  // unconditional branch instructions
+  if (!Prefix)
+    return operator new(s, Us);
+
+  assert(Us == 1 && "Other than one Use allocated?");
+  typedef PointerIntPair<void*, 2, Use::PrevPtrTag> TaggedPrefix;
+  void *Raw = ::operator new(s + sizeof(TaggedPrefix) + sizeof(Use) * Us);
+  TaggedPrefix *Pre = static_cast<TaggedPrefix*>(Raw);
+  Pre->setFromOpaqueValue(0);
+  void *Storage = Pre + 1; // skip over prefix
+  Use *Start = static_cast<Use*>(Storage);
+  Use *End = Start + Us;
+  User *Obj = reinterpret_cast<User*>(End);
+  Obj->OperandList = Start;
+  Obj->NumOperands = Us;
+  Use::initTags(Start, End);
+  return Obj;
+}
+
+//===----------------------------------------------------------------------===//
+//                         User operator delete Implementation
+//===----------------------------------------------------------------------===//
+
+void User::operator delete(void *Usr) {
+  User *Start = static_cast<User*>(Usr);
+  Use *Storage = static_cast<Use*>(Usr) - Start->NumOperands;
+  //
+  // look for a variadic User
+  if (Storage == Start->OperandList) {
+    ::operator delete(Storage);
+    return;
+  }
+  //
+  // check for the flag whether the destructor has detected a prefixed
+  // allocation, in which case we remove the flag and delete starting
+  // at OperandList
+  if (reinterpret_cast<intptr_t>(Start->OperandList) & 1) {
+    ::operator delete(reinterpret_cast<char*>(Start->OperandList) - 1);
+    return;
+  }
+  //
+  // in all other cases just delete the nullary User (covers hung-off
+  // uses also
+  ::operator delete(Usr);
+}
+
 } // End llvm namespace