[DestroyAddrHoisting] Don't fold for invalid paths.

include/swift/SIL/MemAccessUtils.h

@@ -1272,7 +1272,8 @@ struct AccessPathWithBase {
 // The "product leaves" are the leaves obtained by only looking through type
 // products (structs and tuples) and NOT type sums (enums).
 void visitProductLeafAccessPathNodes(
-    SILValue address, TypeExpansionContext tec, SILModule &module,
+    AccessPath rootPath, SILValue address, TypeExpansionContext tec,
+    SILModule &module,
     std::function<void(AccessPath::PathNode, SILType)> visitor);
 
 inline AccessPath AccessPath::compute(SILValue address) {

lib/SIL/Utils/MemAccessUtils.cpp

@@ -1436,10 +1436,12 @@ AccessPathWithBase AccessPathWithBase::computeInScope(SILValue address) {
 }
 
 void swift::visitProductLeafAccessPathNodes(
-    SILValue address, TypeExpansionContext tec, SILModule &module,
+    AccessPath rootPath, SILValue address, TypeExpansionContext tec,
+    SILModule &module,
     std::function<void(AccessPath::PathNode, SILType)> visitor) {
+  assert(rootPath.isValid());
+  assert(AccessPath::compute(address) == rootPath);
   SmallVector<std::pair<SILType, IndexTrieNode *>, 32> worklist;
-  auto rootPath = AccessPath::compute(address);
   auto *node = rootPath.getPathNode().node;
   worklist.push_back({address->getType(), node});
   while (!worklist.empty()) {

lib/SILOptimizer/Transforms/DestroyAddrHoisting.cpp

@@ -560,6 +560,13 @@ bool HoistDestroys::rewriteDestroys(const AccessStorage &storage,
 bool HoistDestroys::foldBarrier(SILInstruction *barrier,
                                 const AccessStorage &storage,
                                 const DeinitBarriers &deinitBarriers) {
+  auto rootPath = AccessPath::compute(storageRoot);
+  if (!rootPath.isValid()) {
+    // [invalid_access_path] The access path to storageRoot isn't understood.
+    // It can't be determined whether all of its leaves have been visited, so
+    // foldability can't be determined. Bail.
+    return false;
+  }
 
   // The load [copy]s which will be folded into load [take]s if folding is
   // possible.
@@ -592,7 +599,8 @@ bool HoistDestroys::foldBarrier(SILInstruction *barrier,
   // it.
   SmallPtrSet<AccessPath::PathNode, 16> trivialLeaves;
 
-  visitProductLeafAccessPathNodes(storageRoot, typeExpansionContext, module,
+  visitProductLeafAccessPathNodes(rootPath, storageRoot, typeExpansionContext,
+                                  module,
                                   [&](AccessPath::PathNode node, SILType ty) {
                                     if (ty.isTrivial(*function))
                                       return;
@@ -744,10 +752,16 @@ bool HoistDestroys::checkFoldingBarrier(
     // of the root storage which would be folded if folding were possible.
     // Find its nontrivial product leaves and remove them from the set of
     // leaves of the root storage which we're wating to see.
+    auto rootPath = AccessPath::compute(address);
+    // [invalid_access_path] The access path to storageRoot was understood, and
+    // address has identical storage to its storage.  The access path to address
+    // must be valid.
+    assert(rootPath.isValid());
+
     bool alreadySawLeaf = false;
     bool alreadySawTrivialSubleaf = false;
     visitProductLeafAccessPathNodes(
-        address, typeExpansionContext, module,
+        rootPath, address, typeExpansionContext, module,
         [&](AccessPath::PathNode node, SILType ty) {
           if (ty.isTrivial(*function)) {
             bool inserted = !trivialLeaves.insert(node).second;

test/SILOptimizer/hoist_destroy_addr.sil

@@ -1179,3 +1179,23 @@ entry(%addr : $*MoE):
   %retval = tuple ()
   return %retval : $()
 }
+
+sil @getPointer : $@convention(thin) () -> Builtin.RawPointer
+
+struct Nontrivial {
+  var guts: Builtin.AnyObject
+}
+
+sil [ossa] @rdar121327964 : $@convention(method) (@owned Nontrivial) -> () {
+bb0(%0 : @owned $Nontrivial):
+  %6 = function_ref @getPointer : $@convention(thin) () -> Builtin.RawPointer
+  %7 = apply %6() : $@convention(thin) () -> Builtin.RawPointer
+  %8 = pointer_to_address %7 : $Builtin.RawPointer to [strict] $*Nontrivial
+  %9 = copy_value %0 : $Nontrivial
+  %10 = begin_access [modify] [dynamic] %8 : $*Nontrivial
+  store %9 to [assign] %10 : $*Nontrivial
+  end_access %10 : $*Nontrivial
+  destroy_value %0 : $Nontrivial
+  %14 = tuple ()
+  return %14 : $()
+}