We want to use extension SPV_KHR_variable_pointers with vulkan memory (KhronosGroup#6121)

model, but shader compiler crashes.

The typical case is passing the buffer to a function and use it. In
function, we need to load the real buffer from variable pointers, it's
okay.

But when we run pass `upgrade-memory-model`, we missed to handle the
`OpLoad` with variable pointers, which resulted in missing 1 dimension
to calculate the access element type. `OpStore` also has the same
problem.

Moreover, `OpLoad` and `OpStore` shouldn't be marked as
`NonPrivatePointer` if the target pointer is storage class Function or
Private.

Author: GinShio

source/opt/upgrade_memory_model.cpp

@@ -160,14 +160,38 @@ void UpgradeMemoryModel::UpgradeMemoryAndImages() {
       }
 
       switch (inst->opcode()) {
-        case spv::Op::OpLoad:
+        case spv::Op::OpLoad: {
+          Instruction* src_pointer = context()->get_def_use_mgr()->GetDef(
+              inst->GetSingleWordInOperand(0u));
+          analysis::Type* src_type =
+              context()->get_type_mgr()->GetType(src_pointer->type_id());
+          auto storage_class = src_type->AsPointer()->storage_class();
+          if (storage_class == spv::StorageClass::Function ||
+              storage_class == spv::StorageClass::Private) {
+            // If the buffer from function variable or private variable, flag
+            // NonPrivatePointer is unnecessary.
+            is_coherent = false;
+          }
           UpgradeFlags(inst, 1u, is_coherent, is_volatile, kVisibility,
                        kMemory);
           break;
-        case spv::Op::OpStore:
+        }
+        case spv::Op::OpStore: {
+          Instruction* src_pointer = context()->get_def_use_mgr()->GetDef(
+              inst->GetSingleWordInOperand(0u));
+          analysis::Type* src_type =
+              context()->get_type_mgr()->GetType(src_pointer->type_id());
+          auto storage_class = src_type->AsPointer()->storage_class();
+          if (storage_class == spv::StorageClass::Function ||
+              storage_class == spv::StorageClass::Private) {
+            // If the buffer from function variable or private variable, flag
+            // NonPrivatePointer is unnecessary.
+            is_coherent = false;
+          }
           UpgradeFlags(inst, 2u, is_coherent, is_volatile, kAvailability,
                        kMemory);
           break;
+        }
         case spv::Op::OpCopyMemory:
         case spv::Op::OpCopyMemorySized:
           start_operand = inst->opcode() == spv::Op::OpCopyMemory ? 2u : 3u;
@@ -366,6 +390,21 @@ std::pair<bool, bool> UpgradeMemoryModel::TraceInstruction(
         indices.push_back(inst->GetSingleWordInOperand(i));
       }
       break;
+    case spv::Op::OpLoad:
+      if (context()->get_type_mgr()->GetType(inst->type_id())->AsPointer()) {
+        analysis::Integer int_ty(32, false);
+        uint32_t int_id =
+            context()->get_type_mgr()->GetTypeInstruction(&int_ty);
+        const analysis::Constant* constant =
+            context()->get_constant_mgr()->GetConstant(
+                context()->get_type_mgr()->GetType(int_id), {0u});
+        uint32_t constant_id = context()
+                                   ->get_constant_mgr()
+                                   ->GetDefiningInstruction(constant)
+                                   ->result_id();
+
+        indices.push_back(constant_id);
+      }
     default:
       break;
   }