"Ghostify" embedded sentinels. This is a real win in all cases

because less bytes are allocated and subobject construction is gone.
For reference how it works, see BasicBlock.h.
Btw. it is very assuring to see that somebody has invented
this ilist-embedded sentinel technique before me :-)

llvm-svn: 66026

3 files changed, 10 insertions, 9 deletions

diff --git a/llvm/include/llvm/CodeGen/MachineBasicBlock.h b/llvm/include/llvm/CodeGen/MachineBasicBlock.h
index 54ac47008f2..5a9f3991f2c 100644
--- a/llvm/include/llvm/CodeGen/MachineBasicBlock.h
+++ b/llvm/include/llvm/CodeGen/MachineBasicBlock.h
@@ -26,14 +26,16 @@ class MachineFunction;
 template <>
 struct ilist_traits<MachineInstr> : public ilist_default_traits<MachineInstr> {
 private:
-  mutable MachineInstr Sentinel;
+  mutable ilist_node<MachineInstr> Sentinel;
 
   // this is only set by the MachineBasicBlock owning the LiveList
   friend class MachineBasicBlock;
   MachineBasicBlock* Parent;
 
 public:
-  MachineInstr *createSentinel() const { return &Sentinel; }
+  MachineInstr *createSentinel() const {
+    return static_cast<MachineInstr*>(&Sentinel);
+  }
   void destroySentinel(MachineInstr *) const {}
 
   void addNodeToList(MachineInstr* N);
diff --git a/llvm/include/llvm/CodeGen/MachineFunction.h b/llvm/include/llvm/CodeGen/MachineFunction.h
index 689e4357b1d..1371f1d0cdf 100644
--- a/llvm/include/llvm/CodeGen/MachineFunction.h
+++ b/llvm/include/llvm/CodeGen/MachineFunction.h
@@ -37,9 +37,11 @@ class TargetMachine;
 template <>
 struct ilist_traits<MachineBasicBlock>
     : public ilist_default_traits<MachineBasicBlock> {
-  mutable MachineBasicBlock Sentinel;
+  mutable ilist_node<MachineBasicBlock> Sentinel;
 public:
-  MachineBasicBlock *createSentinel() const { return &Sentinel; }
+  MachineBasicBlock *createSentinel() const {
+    return static_cast<MachineBasicBlock*>(&Sentinel);
+  }
   void destroySentinel(MachineBasicBlock *) const {}
 
   void addNodeToList(MachineBasicBlock* MBB);
diff --git a/llvm/include/llvm/CodeGen/SelectionDAG.h b/llvm/include/llvm/CodeGen/SelectionDAG.h
index 9ecba590dd4..fe89fe05460 100644
--- a/llvm/include/llvm/CodeGen/SelectionDAG.h
+++ b/llvm/include/llvm/CodeGen/SelectionDAG.h
@@ -39,13 +39,10 @@ class FunctionLoweringInfo;
 
 template<> struct ilist_traits<SDNode> : public ilist_default_traits<SDNode> {
 private:
-  mutable SDNode Sentinel;
+  mutable ilist_node<SDNode> Sentinel;
 public:
-  ilist_traits() : Sentinel(ISD::DELETED_NODE, DebugLoc::getUnknownLoc(),
-                            SDVTList()) {}
-
   SDNode *createSentinel() const {
-    return &Sentinel;
+    return static_cast<SDNode*>(&Sentinel);
   }
   static void destroySentinel(SDNode *) {}