Feature-gate stake program (#13394)

* Add legacy stake-program handling

* Strip out duplicative legacy code

* Add feature for stake-program-fix

* Feature-deploy new stake program

* Expand comment

runtime/src/builtins.rs

@@ -17,10 +17,12 @@ fn genesis_builtins() -> Vec<Builtin> {
             solana_vote_program::id(),
             solana_vote_program::vote_instruction::process_instruction,
         ),
+        // Remove legacy_stake_processor and move stake_instruction::process_instruction back to
+        // genesis_builtins around the v1.6 timeframe
         Builtin::new(
             "stake_program",
             solana_stake_program::id(),
-            solana_stake_program::stake_instruction::process_instruction,
+            solana_stake_program::legacy_stake_processor::process_instruction,
         ),
         Builtin::new(
             "config_program",
@@ -37,16 +39,34 @@ pub enum ActivationType {
 }
 
 /// Builtin programs activated dynamically by feature
+///
+/// Note: If the feature_builtin is intended to replace another builtin program, it must have a new
+/// name.
+/// This is to enable the runtime to determine categorically whether the builtin update has
+/// occurred, and preserve idempotency in Bank::add_native_program across genesis, snapshot, and
+/// normal child Bank creation.
+/// https://github.com/solana-labs/solana/blob/84b139cc94b5be7c9e0c18c2ad91743231b85a0d/runtime/src/bank.rs#L1723
 fn feature_builtins() -> Vec<(Builtin, Pubkey, ActivationType)> {
-    vec![(
-        Builtin::new(
-            "secp256k1_program",
-            solana_sdk::secp256k1_program::id(),
-            solana_secp256k1_program::process_instruction,
+    vec![
+        (
+            Builtin::new(
+                "secp256k1_program",
+                solana_sdk::secp256k1_program::id(),
+                solana_secp256k1_program::process_instruction,
+            ),
+            feature_set::secp256k1_program_enabled::id(),
+            ActivationType::NewProgram,
         ),
-        feature_set::secp256k1_program_enabled::id(),
-        ActivationType::NewProgram,
-    )]
+        (
+            Builtin::new(
+                "stake_program_v2",
+                solana_stake_program::id(),
+                solana_stake_program::stake_instruction::process_instruction,
+            ),
+            feature_set::stake_program_v2::id(),
+            ActivationType::NewVersion,
+        ),
+    ]
 }
 
 pub(crate) fn get() -> Builtins {