Implement automatically updated def/use lists for all MachineInstr register

operands.  The lists are currently kept in MachineRegisterInfo, but it does
not yet provide an iterator interface to them.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@45477 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/MachineRegisterInfo.cpp

@@ -1,4 +1,4 @@
-//===-- MachineRegisterInfo.cpp -------------------------------------------===//
+//===-- lib/Codegen/MachineRegisterInfo.cpp -------------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
@@ -17,4 +17,30 @@ using namespace llvm;
 MachineRegisterInfo::MachineRegisterInfo(const MRegisterInfo &MRI) {
   VRegInfo.reserve(256);
   UsedPhysRegs.resize(MRI.getNumRegs());
+  
+  // Create the physreg use/def lists.
+  PhysRegUseDefLists = new MachineOperand*[MRI.getNumRegs()];
+  memset(PhysRegUseDefLists, 0, sizeof(MachineOperand*)*MRI.getNumRegs());
+}
+
+MachineRegisterInfo::~MachineRegisterInfo() {
+#ifndef NDEBUG
+  for (unsigned i = 0, e = VRegInfo.size(); i != e; ++i)
+    assert(VRegInfo[i].second == 0 && "Vreg use list non-empty still?");
+#endif
+  delete [] PhysRegUseDefLists;
+}
+
+/// HandleVRegListReallocation - We just added a virtual register to the
+/// VRegInfo info list and it reallocated.  Update the use/def lists info
+/// pointers.
+void MachineRegisterInfo::HandleVRegListReallocation() {
+  // The back pointers for the vreg lists point into the previous vector.
+  // Update them to point to their correct slots.
+  for (unsigned i = 0, e = VRegInfo.size(); i != e; ++i) {
+    MachineOperand *List = VRegInfo[i].second;
+    if (!List) continue;
+    // Update the back-pointer to be accurate once more.
+    List->Contents.Reg.Prev = &VRegInfo[i].second;
+  }
 }