[DSE] Make DSEState non-copyable (NFC)

As it contains a self-reference, the default copy/move ctors
would not be safe.

Move the DSEState::get() method into the ctor to make sure no move
occurs here even without NRVO.

This is a speculative fix for test failures on
llvm-clang-x86_64-expensive-checks-win.

Author: nikic

llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp

@@ -898,30 +898,29 @@ struct DSEState {
   /// basic block.
   DenseMap<BasicBlock *, InstOverlapIntervalsTy> IOLs;
 
+  // Class contains self-reference, make sure it's not copied/moved.
+  DSEState(const DSEState &) = delete;
+  DSEState &operator=(const DSEState &) = delete;
+
   DSEState(Function &F, AliasAnalysis &AA, MemorySSA &MSSA, DominatorTree &DT,
            PostDominatorTree &PDT, const TargetLibraryInfo &TLI,
            const LoopInfo &LI)
       : F(F), AA(AA), EI(DT, LI), BatchAA(AA, &EI), MSSA(MSSA), DT(DT),
-        PDT(PDT), TLI(TLI), DL(F.getParent()->getDataLayout()), LI(LI) {}
-
-  static DSEState get(Function &F, AliasAnalysis &AA, MemorySSA &MSSA,
-                      DominatorTree &DT, PostDominatorTree &PDT,
-                      const TargetLibraryInfo &TLI, const LoopInfo &LI) {
-    DSEState State(F, AA, MSSA, DT, PDT, TLI, LI);
+        PDT(PDT), TLI(TLI), DL(F.getParent()->getDataLayout()), LI(LI) {
     // Collect blocks with throwing instructions not modeled in MemorySSA and
     // alloc-like objects.
     unsigned PO = 0;
     for (BasicBlock *BB : post_order(&F)) {
-      State.PostOrderNumbers[BB] = PO++;
+      PostOrderNumbers[BB] = PO++;
       for (Instruction &I : *BB) {
         MemoryAccess *MA = MSSA.getMemoryAccess(&I);
         if (I.mayThrow() && !MA)
-          State.ThrowingBlocks.insert(I.getParent());
+          ThrowingBlocks.insert(I.getParent());
 
         auto *MD = dyn_cast_or_null<MemoryDef>(MA);
-        if (MD && State.MemDefs.size() < MemorySSADefsPerBlockLimit &&
-            (State.getLocForWriteEx(&I) || State.isMemTerminatorInst(&I)))
-          State.MemDefs.push_back(MD);
+        if (MD && MemDefs.size() < MemorySSADefsPerBlockLimit &&
+            (getLocForWriteEx(&I) || isMemTerminatorInst(&I)))
+          MemDefs.push_back(MD);
       }
     }
 
@@ -931,14 +930,12 @@ struct DSEState {
       if (AI.hasPassPointeeByValueCopyAttr()) {
         // For byval, the caller doesn't know the address of the allocation.
         if (AI.hasByValAttr())
-          State.InvisibleToCallerBeforeRet.insert({&AI, true});
-        State.InvisibleToCallerAfterRet.insert({&AI, true});
+          InvisibleToCallerBeforeRet.insert({&AI, true});
+        InvisibleToCallerAfterRet.insert({&AI, true});
       }
 
     // Collect whether there is any irreducible control flow in the function.
-    State.ContainsIrreducibleLoops = mayContainIrreducibleControl(F, &LI);
-
-    return State;
+    ContainsIrreducibleLoops = mayContainIrreducibleControl(F, &LI);
   }
 
   /// Return 'OW_Complete' if a store to the 'KillingLoc' location (by \p
@@ -1935,7 +1932,7 @@ static bool eliminateDeadStores(Function &F, AliasAnalysis &AA, MemorySSA &MSSA,
                                 const LoopInfo &LI) {
   bool MadeChange = false;
 
-  DSEState State = DSEState::get(F, AA, MSSA, DT, PDT, TLI, LI);
+  DSEState State(F, AA, MSSA, DT, PDT, TLI, LI);
   // For each store:
   for (unsigned I = 0; I < State.MemDefs.size(); I++) {
     MemoryDef *KillingDef = State.MemDefs[I];