[gas] Do not charge for loading Sui Framework or Move stdlib

- The code for the Sui Framework and Move stdlib will live directly in the validator binary, so using these won't actually trigger an on-chain read. No need to charge users for this.
- For Sui Framework developers, it's quite cumbersome to change the gas snapshot tests every time code in the Sui Framework changes (since it tweaks the loading cost). This is a pain for us today, but in the future it will also be a pain for third-party devs--a change in the size of the Sui Framework due to a framework upgrade will change the gas cost for a dependent package `P` even if the actual functions called by `P` are unchanged by the upgrade.

crates/sui-core/src/execution_engine.rs

@@ -28,7 +28,6 @@ use sui_types::storage::{ChildObjectResolver, DeleteKind, ParentSync, WriteKind}
 #[cfg(test)]
 use sui_types::temporary_store;
 use sui_types::temporary_store::InnerTemporaryStore;
-use sui_types::SUI_SYSTEM_STATE_OBJECT_SHARED_VERSION;
 use sui_types::{
     base_types::{ObjectID, ObjectRef, SuiAddress, TransactionDigest, TxContext},
     gas::SuiGasStatus,
@@ -41,6 +40,9 @@ use sui_types::{
     sui_system_state::{ADVANCE_EPOCH_FUNCTION_NAME, SUI_SYSTEM_MODULE_NAME},
     SUI_FRAMEWORK_ADDRESS, SUI_SYSTEM_STATE_OBJECT_ID,
 };
+use sui_types::{
+    MOVE_STDLIB_OBJECT_ID, SUI_FRAMEWORK_OBJECT_ID, SUI_SYSTEM_STATE_OBJECT_SHARED_VERSION,
+};
 
 use crate::authority::TemporaryStore;
 
@@ -118,8 +120,10 @@ fn charge_gas_for_object_read<S>(
     // fetching only unique objects.
     let total_size = temporary_store
         .objects()
-        .values()
-        .map(|obj| obj.object_size_for_gas_metering())
+        .iter()
+        // don't charge for loading Sui Framework or Move stdlib
+        .filter(|(id, _)| *id != &SUI_FRAMEWORK_OBJECT_ID && *id != &MOVE_STDLIB_OBJECT_ID)
+        .map(|(_, obj)| obj.object_size_for_gas_metering())
         .sum();
     gas_status.charge_storage_read(total_size)
 }

crates/sui-core/src/unit_tests/gas_tests.rs

@@ -18,6 +18,7 @@ use sui_types::{
     crypto::get_key_pair,
     gas::{SuiGasStatus, MAX_GAS_BUDGET, MIN_GAS_BUDGET},
 };
+use sui_types::{MOVE_STDLIB_OBJECT_ID, SUI_FRAMEWORK_OBJECT_ID};
 
 #[tokio::test]
 async fn test_tx_less_than_minimum_gas_budget() {
@@ -298,7 +299,14 @@ async fn test_publish_gas() -> anyhow::Result<()> {
     gas_status.charge_storage_read(
         genesis_objects
             .iter()
-            .map(|o| o.object_size_for_gas_metering())
+            // do not charge for loads of the Sui Framework
+            .filter_map(|o| {
+                if o.id() != SUI_FRAMEWORK_OBJECT_ID && o.id() != MOVE_STDLIB_OBJECT_ID {
+                    Some(o.object_size_for_gas_metering())
+                } else {
+                    None
+                }
+            })
             .sum(),
     )?;
     gas_status.charge_storage_read(gas_object.object_size_for_gas_metering())?;

crates/sui-cost/tests/snapshots/empirical_transaction_cost__good_snapshot.snap

@@ -4,12 +4,12 @@ expression: common_costs_actual
 ---
 {
   "MergeCoin": {
-    "computation_cost": 733,
+    "computation_cost": 63,
     "storage_cost": 32,
     "storage_rebate": 0
   },
   "Publish": {
-    "computation_cost": 984,
+    "computation_cost": 226,
     "storage_cost": 119,
     "storage_rebate": 0
   },
@@ -29,7 +29,7 @@ expression: common_costs_actual
     "storage_rebate": 15
   },
   "SplitCoin": {
-    "computation_cost": 844,
+    "computation_cost": 173,
     "storage_cost": 80,
     "storage_rebate": 0
   },

crates/sui-types/src/lib.rs

@@ -56,6 +56,7 @@ pub mod utils;
 /// 0x1-- account address where Move stdlib modules are stored
 /// Same as the ObjectID
 pub const MOVE_STDLIB_ADDRESS: AccountAddress = AccountAddress::ONE;
+pub const MOVE_STDLIB_OBJECT_ID: ObjectID = ObjectID::from_single_byte(1);
 
 /// 0x2-- account address where sui framework modules are stored
 /// Same as the ObjectID