[VPlan][NFCI] Small code quality fixes in VPlanHCFGBuilder and VPlanSLP

Addresses some code quality issues found during an internal code review. Specifically, marking implicitly defined copy constructor and copy assignment for VPInterleavedAccessInfo as delete in VPlanSLP.h, and fixing two instances where null dereferences were technically possible in VPlanHCFGBuilder.cpp.

Author: calebwat

llvm/lib/Transforms/Vectorize/VPlanHCFGBuilder.cpp

@@ -378,6 +378,7 @@ void PlainCFGBuilder::buildPlainCFG(
     VPBasicBlock *VPBB = getOrCreateVPBB(BB);
     VPRegionBlock *Region = VPBB->getParent();
     Loop *LoopForBB = LI->getLoopFor(BB);
+    assert(LoopForBB && "Expected block to be inside a loop");
     // Set VPBB predecessors in the same order as they are in the incoming BB.
     if (!isHeaderBB(BB, LoopForBB)) {
       setVPBBPredsFromBB(VPBB, BB);
@@ -423,7 +424,7 @@ void PlainCFGBuilder::buildPlainCFG(
     BasicBlock *IRSucc1 = BI->getSuccessor(1);
     VPBasicBlock *Successor0 = getOrCreateVPBB(IRSucc0);
     VPBasicBlock *Successor1 = getOrCreateVPBB(IRSucc1);
-    if (BB == LoopForBB->getLoopLatch()) {
+    if (BB == LoopForBB->getLoopLatch() && Region) {
       // For a latch we need to set the successor of the region rather than that
       // of VPBB and it should be set to the exit, i.e., non-header successor,
       // except for the top region, which is handled elsewhere.
@@ -437,15 +438,13 @@ void PlainCFGBuilder::buildPlainCFG(
 
     // Don't connect any blocks outside the current loop except the latch for
     // now. The latch is handled above.
-    if (LoopForBB) {
-      if (!LoopForBB->contains(IRSucc0)) {
-        VPBB->setOneSuccessor(Successor1);
-        continue;
-      }
-      if (!LoopForBB->contains(IRSucc1)) {
-        VPBB->setOneSuccessor(Successor0);
-        continue;
-      }
+    if (!LoopForBB->contains(IRSucc0)) {
+      VPBB->setOneSuccessor(Successor1);
+      continue;
+    }
+    if (!LoopForBB->contains(IRSucc1)) {
+      VPBB->setOneSuccessor(Successor0);
+      continue;
     }
 
     VPBB->setTwoSuccessors(Successor0, Successor1);

llvm/lib/Transforms/Vectorize/VPlanSLP.h

@@ -48,6 +48,8 @@ class VPInterleavedAccessInfo {
 
 public:
   VPInterleavedAccessInfo(VPlan &Plan, InterleavedAccessInfo &IAI);
+  VPInterleavedAccessInfo(const VPInterleavedAccessInfo &) = delete;
+  VPInterleavedAccessInfo &operator=(const VPInterleavedAccessInfo &) = delete;
 
   ~VPInterleavedAccessInfo() {
     // Avoid releasing a pointer twice.