[contracts] Add per local weight for function call (#12806)

* Add per local weight for function call

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

* Update frame/contracts/src/benchmarking/mod.rs

Co-authored-by: Alexander Theißen <alex.theissen@me.com>

* apply suggestions from code review

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

* Update frame/contracts/src/benchmarking/mod.rs

Co-authored-by: Alexander Theißen <alex.theissen@me.com>

* tune the benchmark

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

* fix benches

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

Co-authored-by: command-bot <>
Co-authored-by: Alexander Theißen <alex.theissen@me.com>

substrate/frame/contracts/src/schedule.rs

@@ -118,6 +118,12 @@ pub struct Limits {
 	/// the linear memory limit `memory_pages` applies to them.
 	pub globals: u32,
 
+	/// Maximum number of locals a function can have.
+	///
+	/// As wasm engine initializes each of the local, we need to limit their number to confine
+	/// execution costs.
+	pub locals: u32,
+
 	/// Maximum numbers of parameters a function can have.
 	///
 	/// Those need to be limited to prevent a potentially exploitable interaction with
@@ -212,6 +218,7 @@ pub struct InstructionWeights<T: Config> {
 	pub call: u32,
 	pub call_indirect: u32,
 	pub call_indirect_per_param: u32,
+	pub call_per_local: u32,
 	pub local_get: u32,
 	pub local_set: u32,
 	pub local_tee: u32,
@@ -522,6 +529,7 @@ impl Default for Limits {
 			// No stack limit required because we use a runtime resident execution engine.
 			stack_height: None,
 			globals: 256,
+			locals: 1024,
 			parameters: 128,
 			memory_pages: 16,
 			// 4k function pointers (This is in count not bytes).
@@ -552,6 +560,7 @@ impl<T: Config> Default for InstructionWeights<T> {
 			call: cost_instr!(instr_call, 2),
 			call_indirect: cost_instr!(instr_call_indirect, 3),
 			call_indirect_per_param: cost_instr!(instr_call_indirect_per_param, 1),
+			call_per_local: cost_instr!(instr_call_per_local, 1),
 			local_get: cost_instr!(instr_local_get, 1),
 			local_set: cost_instr!(instr_local_set, 1),
 			local_tee: cost_instr!(instr_local_tee, 2),
@@ -792,6 +801,10 @@ impl<'a, T: Config> gas_metering::Rules for ScheduleRules<'a, T> {
 		// The cost for growing is therefore already included in the instruction cost.
 		gas_metering::MemoryGrowCost::Free
 	}
+
+	fn call_per_local_cost(&self) -> u32 {
+		self.schedule.instruction_weights.call_per_local
+	}
 }
 
 #[cfg(test)]