contracts: Add instantiation_nonce API (#12800)

* Add `instantiation_nonce` API

* Fixes for tests

* Update frame/contracts/src/schedule.rs

Co-authored-by: Sasha Gryaznov <hi@agryaznov.com>

* ".git/.scripts/bench-bot.sh" pallet dev pallet_contracts

Co-authored-by: Sasha Gryaznov <hi@agryaznov.com>
Co-authored-by: command-bot <>

substrate/frame/contracts/src/wasm/runtime.rs

@@ -265,6 +265,8 @@ pub enum RuntimeCosts {
 	ReentrantCount,
 	/// Weight of calling `account_reentrance_count`
 	AccountEntranceCount,
+	/// Weight of calling `instantiation_nonce`
+	InstantationNonce,
 }
 
 impl RuntimeCosts {
@@ -344,6 +346,7 @@ impl RuntimeCosts {
 			EcdsaToEthAddress => s.ecdsa_to_eth_address,
 			ReentrantCount => s.reentrance_count,
 			AccountEntranceCount => s.account_reentrance_count,
+			InstantationNonce => s.instantiation_nonce,
 		};
 		RuntimeToken {
 			#[cfg(test)]
@@ -2614,4 +2617,14 @@ pub mod env {
 			ctx.read_sandbox_memory_as(memory, account_ptr)?;
 		Ok(ctx.ext.account_reentrance_count(&account_id))
 	}
+
+	/// Returns a nonce that is unique per contract instantiation.
+	///
+	/// The nonce is incremented for each succesful contract instantiation. This is a
+	/// sensible default salt for contract instantiations.
+	#[unstable]
+	fn instantiation_nonce(ctx: _, _memory: _) -> Result<u64, TrapReason> {
+		ctx.charge_gas(RuntimeCosts::InstantationNonce)?;
+		Ok(ctx.ext.nonce())
+	}
 }