[lldb] Increase the maximum number of classes we can read from shared cache

[bulbazord]

Summary

The shared cache has grown past the previously hardcoded limit. As a
temporary measure, I am increasing the hardcoded number of classes we
can expect to read from the shared cache. This is not a good long-term
solution.

[jasonmolenda]

LGTM. You might want to mention why it isn't sustainable -- because we must allocate memory in the inferior process, and some inferior processes have quite small memory limits.

[bulbazord]

In D153817#4450534, @jasonmolenda wrote:

LGTM. You might want to mention why it isn't sustainable -- because we must allocate memory in the inferior process, and some inferior processes have quite small memory limits.

Sounds good, will update.

[bulbazord]

Update FIXME with more info

[bulbazord]

Updating number

lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCRuntimeV2.cpp

const lldb::addr_t shared_cache_base_addr =
       m_runtime.GetSharedCacheBaseAddress();
 
   if (objc_opt_ptr == LLDB_INVALID_ADDRESS ||
       shared_cache_base_addr == LLDB_INVALID_ADDRESS)
     return DescriptorMapUpdateResult::Fail();
 
   // The number of entries to pre-allocate room for.
   // Each entry is (addrsize + 4) bytes
-  const uint32_t max_num_classes = 163840;
+  // FIXME: It is not sustainable to continue incrementing this value every time
+  // the shared cache grows. This is because it requires allocating memory in
+  // the inferior process and some inferior processes have small memory limits.
+  const uint32_t max_num_classes = 212992;
 
   UtilityFunction *get_class_info_code = GetClassInfoUtilityFunction(exe_ctx);
   if (!get_class_info_code) {
     // The callee will have already logged a useful error message.
     return DescriptorMapUpdateResult::Fail();
   }
 
   FunctionCaller *get_shared_cache_class_info_function =