[ownership] Assume values/operands in SILGlobalVariable blocks are not in OSSA.

Operationally it just means that in SILGlobalVariable blocks, all operands have
ownership constraint:

  {OwnershipKind::Any, UseLifetimeConstraint::NonLifetimeEnding}

and all values yield an ownership kind of: OwnershipKind::None.

Author: gottesmm

lib/SIL/IR/OperandOwnership.cpp

@@ -922,10 +922,17 @@ Optional<OwnershipConstraint> Operand::getOwnershipConstraint() const {
   // We do not ever call this function when an instruction isn't in a block.
   assert(getUser()->getParent() &&
          "Can not lookup ownership constraint unless inserted into block");
-  if (auto *block = getUser()->getParent())
-    if (auto *func = block->getParent())
-      if (!func->hasOwnership())
-        return {{OwnershipKind::Any, UseLifetimeConstraint::NonLifetimeEnding}};
+  if (auto *block = getUser()->getParent()) {
+    auto *func = block->getParent();
+    if (!func) {
+      // If we don't have a function, then we must have a SILGlobalVariable. In
+      // that case, we act as if we aren't in ownership.
+      return {{OwnershipKind::Any, UseLifetimeConstraint::NonLifetimeEnding}};
+    }
+
+    if (!func->hasOwnership())
+      return {{OwnershipKind::Any, UseLifetimeConstraint::NonLifetimeEnding}};
+  }
 
   OwnershipConstraintClassifier classifier(getUser()->getModule(), *this);
   return classifier.visit(const_cast<SILInstruction *>(getUser()));

lib/SIL/IR/ValueOwnership.cpp

@@ -591,10 +591,19 @@ ValueOwnershipKind SILValue::getOwnershipKind() const {
   //
   // We assume that any time we are in SILBuilder and call this without having a
   // value in a block yet, ossa is enabled.
-  if (auto *block = Value->getParentBlock())
-    if (auto *f = block->getParent())
-      if (!f->hasOwnership())
-        return OwnershipKind::None;
+  if (auto *block = Value->getParentBlock()) {
+    auto *f = block->getParent();
+    // If our block isn't in a function, then it must be in a global
+    // variable. We don't verify ownership there so just return
+    // OwnershipKind::None.
+    if (!f)
+      return OwnershipKind::None;
+
+    // Now that we know that we do have a block/function, check if we have
+    // ownership.
+    if (!f->hasOwnership())
+      return OwnershipKind::None;
+  }
 
   ValueOwnershipKindClassifier Classifier;
   auto result = Classifier.visit(const_cast<ValueBase *>(Value));