[CodeGen] LiveRegMatrix: Use allocator through a unique_ptr (#120556)

`LIU::Matrix` holds on to a pointer to the allocator in LiveRegMatrix and is left hanging when the allocator moves with the LiveRegMatrix.

This extends the lifetime of the allocator so that it does not get destroyed when moving a LiveRegMatrix object.

Author: optimisan

llvm/include/llvm/CodeGen/LiveRegMatrix.h

@@ -48,7 +48,7 @@ class LiveRegMatrix {
   unsigned UserTag = 0;
 
   // The matrix is represented as a LiveIntervalUnion per register unit.
-  LiveIntervalUnion::Allocator LIUAlloc;
+  std::unique_ptr<LiveIntervalUnion::Allocator> LIUAlloc;
   LiveIntervalUnion::Array Matrix;
 
   // Cached queries per register unit.
@@ -59,15 +59,12 @@ class LiveRegMatrix {
   unsigned RegMaskVirtReg = 0;
   BitVector RegMaskUsable;
 
-  LiveRegMatrix() = default;
+  LiveRegMatrix()
+      : LIUAlloc(std::make_unique<LiveIntervalUnion::Allocator>()) {};
   void releaseMemory();
 
 public:
-  LiveRegMatrix(LiveRegMatrix &&Other)
-      : TRI(Other.TRI), LIS(Other.LIS), VRM(Other.VRM), UserTag(Other.UserTag),
-        Matrix(std::move(Other.Matrix)), Queries(std::move(Other.Queries)),
-        RegMaskTag(Other.RegMaskTag), RegMaskVirtReg(Other.RegMaskVirtReg),
-        RegMaskUsable(std::move(Other.RegMaskUsable)) {}
+  LiveRegMatrix(LiveRegMatrix &&Other) = default;
 
   void init(MachineFunction &MF, LiveIntervals &LIS, VirtRegMap &VRM);
 

llvm/lib/CodeGen/LiveRegMatrix.cpp

@@ -66,7 +66,7 @@ void LiveRegMatrix::init(MachineFunction &MF, LiveIntervals &pLIS,
   unsigned NumRegUnits = TRI->getNumRegUnits();
   if (NumRegUnits != Matrix.size())
     Queries.reset(new LiveIntervalUnion::Query[NumRegUnits]);
-  Matrix.init(LIUAlloc, NumRegUnits);
+  Matrix.init(*LIUAlloc, NumRegUnits);
 
   // Make sure no stale queries get reused.
   invalidateVirtRegs();