From ce4af1bab3381a2bdab56ced6c976448abb37cea Mon Sep 17 00:00:00 2001
From: George Mitenkov <georgemitenk0v@gmail.com>
Date: Thu, 1 Aug 2024 08:00:20 +0100
Subject: [PATCH] [loader] Add feature flag to be able to switch to V2
 implementation

---
 .../src/components/feature_flags.rs                      | 3 +++
 types/src/on_chain_config/aptos_features.rs              | 9 +++++++++
 2 files changed, 12 insertions(+)

diff --git a/aptos-move/aptos-release-builder/src/components/feature_flags.rs b/aptos-move/aptos-release-builder/src/components/feature_flags.rs
index b0d7cc4c172f3..a9f42c0b2b54d 100644
--- a/aptos-move/aptos-release-builder/src/components/feature_flags.rs
+++ b/aptos-move/aptos-release-builder/src/components/feature_flags.rs
@@ -127,6 +127,7 @@ pub enum FeatureFlag {
     EnableEnumTypes,
     EnableResourceAccessControl,
     RejectUnstableBytecodeForScript,
+    UseLoaderV2,
 }
 
 fn generate_features_blob(writer: &CodeWriter, data: &[u64]) {
@@ -336,6 +337,7 @@ impl From<FeatureFlag> for AptosFeatureFlag {
             FeatureFlag::RejectUnstableBytecodeForScript => {
                 AptosFeatureFlag::REJECT_UNSTABLE_BYTECODE_FOR_SCRIPT
             },
+            FeatureFlag::UseLoaderV2 => AptosFeatureFlag::USE_LOADER_V2,
         }
     }
 }
@@ -474,6 +476,7 @@ impl From<AptosFeatureFlag> for FeatureFlag {
             AptosFeatureFlag::REJECT_UNSTABLE_BYTECODE_FOR_SCRIPT => {
                 FeatureFlag::RejectUnstableBytecodeForScript
             },
+            AptosFeatureFlag::USE_LOADER_V2 => FeatureFlag::UseLoaderV2,
         }
     }
 }
diff --git a/types/src/on_chain_config/aptos_features.rs b/types/src/on_chain_config/aptos_features.rs
index 79d2045b551ce..f4c2287297d10 100644
--- a/types/src/on_chain_config/aptos_features.rs
+++ b/types/src/on_chain_config/aptos_features.rs
@@ -92,6 +92,7 @@ pub enum FeatureFlag {
     ENABLE_ENUM_TYPES = 74,
     ENABLE_RESOURCE_ACCESS_CONTROL = 75,
     REJECT_UNSTABLE_BYTECODE_FOR_SCRIPT = 76,
+    USE_LOADER_V2 = 77,
 }
 
 impl FeatureFlag {
@@ -167,6 +168,8 @@ impl FeatureFlag {
             FeatureFlag::ENABLE_ENUM_TYPES,
             FeatureFlag::ENABLE_RESOURCE_ACCESS_CONTROL,
             FeatureFlag::REJECT_UNSTABLE_BYTECODE_FOR_SCRIPT,
+            // TODO(George): Enable this flag when ready.
+            // FeatureFlag::USE_LOADER_V2,
         ]
     }
 }
@@ -304,6 +307,12 @@ impl Features {
         self.is_enabled(FeatureFlag::ABORT_IF_MULTISIG_PAYLOAD_MISMATCH)
     }
 
+    /// If enabled, MoveVM uses the V2 stateless loader API. The flag is used
+    /// to ensure we have both V1 and V2 operating at the same time.
+    pub fn use_loader_v2(&self) -> bool {
+        self.is_enabled(FeatureFlag::USE_LOADER_V2)
+    }
+
     pub fn get_max_identifier_size(&self) -> u64 {
         if self.is_enabled(FeatureFlag::LIMIT_MAX_IDENTIFIER_LENGTH) {
             IDENTIFIER_SIZE_MAX