feat(avm): Set gas allowance in public calls (#5567)

Allows user to set gas allowance in public calls, defaulting to the gas
left in the current frame.

- Adds the `(L1|L2|DA)GASLEFT` instructions.
- Adds a new `GasOpts` option to the
`(Public|Avm)Context.call_public_function` so the user can specify the
gas allocation for a nested public call (ignored in public context, only
used in avm context). Defaults gas to the result of gasleft, minus a
buffer for L2 compute.
- Updates the noir interface codegen to handle this new argument.

avm-transpiler/src/transpile.rs

@@ -795,6 +795,9 @@ fn handle_getter_instruction(
         "avmOpcodeVersion" => AvmOpcode::VERSION,
         "avmOpcodeBlockNumber" => AvmOpcode::BLOCKNUMBER,
         "avmOpcodeTimestamp" => AvmOpcode::TIMESTAMP,
+        "avmOpcodeL1GasLeft" => AvmOpcode::L1GASLEFT,
+        "avmOpcodeL2GasLeft" => AvmOpcode::L2GASLEFT,
+        "avmOpcodeDaGasLeft" => AvmOpcode::DAGASLEFT,
         // "callStackDepth" => AvmOpcode::CallStackDepth,
         _ => panic!(
             "Transpiler doesn't know how to process ForeignCall function {:?}",

l1-contracts/src/core/libraries/ConstantsGen.sol

@@ -69,6 +69,7 @@ library Constants {
   uint256 internal constant INITIALIZATION_SLOT_SEPARATOR = 1000_000_000;
   uint256 internal constant INITIAL_L2_BLOCK_NUM = 1;
   uint256 internal constant BLOB_SIZE_IN_BYTES = 126976;
+  uint256 internal constant NESTED_CALL_L2_GAS_BUFFER = 20000;
   uint256 internal constant MAX_PACKED_PUBLIC_BYTECODE_SIZE_IN_FIELDS = 15000;
   uint256 internal constant MAX_PACKED_BYTECODE_SIZE_PER_PRIVATE_FUNCTION_IN_FIELDS = 3000;
   uint256 internal constant MAX_PACKED_BYTECODE_SIZE_PER_UNCONSTRAINED_FUNCTION_IN_FIELDS = 3000;

noir-projects/aztec-nr/authwit/src/auth.nr

@@ -2,7 +2,7 @@ use dep::aztec::protocol_types::{
     abis::function_selector::FunctionSelector, address::AztecAddress,
     constants::{GENERATOR_INDEX__AUTHWIT_INNER, GENERATOR_INDEX__AUTHWIT_OUTER}, hash::pedersen_hash
 };
-use dep::aztec::{context::{PrivateContext, PublicContext, Context}, hash::hash_args_array};
+use dep::aztec::{context::{PrivateContext, PublicContext, Context, gas::GasOpts}, hash::hash_args_array};
 
 global IS_VALID_SELECTOR = 0xabf64ad4; // 4 first bytes of keccak256("IS_VALID()")
 
@@ -21,7 +21,12 @@ pub fn assert_current_call_valid_authwit(context: &mut PrivateContext, on_behalf
 pub fn assert_current_call_valid_authwit_public(context: &mut PublicContext, on_behalf_of: AztecAddress) {
     let function_selector = FunctionSelector::from_signature("spend_public_authwit(Field)");
     let inner_hash = compute_inner_authwit_hash([context.msg_sender().to_field(), context.selector().to_field(), context.args_hash]);
-    let result = context.call_public_function(on_behalf_of, function_selector, [inner_hash])[0];
+    let result = context.call_public_function(
+        on_behalf_of,
+        function_selector,
+        [inner_hash],
+        GasOpts::default()
+    )[0];
     assert(result == IS_VALID_SELECTOR, "Message not authorized by account");
 }
 // docs:end:assert_current_call_valid_authwit_public

noir-projects/aztec-nr/aztec/src/context.nr

@@ -5,6 +5,7 @@ mod private_context;
 mod public_context;
 mod avm_context;
 mod interface;
+mod gas;
 
 use interface::ContextInterface;
 use private_context::PrivateContext;

noir-projects/aztec-nr/aztec/src/context/avm_context.nr

@@ -1,11 +1,15 @@
-use dep::protocol_types::{address::{AztecAddress, EthAddress}, constants::L1_TO_L2_MESSAGE_LENGTH, header::Header};
+use dep::protocol_types::{
+    address::{AztecAddress, EthAddress},
+    constants::{L1_TO_L2_MESSAGE_LENGTH, NESTED_CALL_L2_GAS_BUFFER, RETURN_VALUES_LENGTH},
+    header::Header
+};
 use dep::protocol_types::traits::Serialize;
 use dep::protocol_types::abis::function_selector::FunctionSelector;
 use dep::protocol_types::abis::public_circuit_public_inputs::PublicCircuitPublicInputs;
-use dep::protocol_types::constants::RETURN_VALUES_LENGTH;
 use crate::context::inputs::avm_context_inputs::AvmContextInputs;
 use crate::context::interface::ContextInterface;
 use crate::context::interface::PublicContextInterface;
+use crate::context::gas::GasOpts;
 
 struct AvmContext {
     inputs: AvmContextInputs,
@@ -54,22 +58,32 @@ impl AvmContext {
 
     fn call_public_function_raw<ARGS_COUNT, RET_COUNT>(
         self: &mut Self,
-        gas: [Field; 3],
+        gas: GasOpts,
         contract_address: AztecAddress,
         temporary_function_selector: Field,
         args: [Field; ARGS_COUNT]
     ) -> ([Field; RET_COUNT], u8) {
-        call(gas, contract_address, args, temporary_function_selector)
+        call(
+            gas_for_call(gas),
+            contract_address,
+            args,
+            temporary_function_selector
+        )
     }
 
     fn static_call_public_function_raw<ARGS_COUNT, RET_COUNT>(
         self: &mut Self,
-        gas: [Field; 3],
+        gas: GasOpts,
         contract_address: AztecAddress,
         temporary_function_selector: Field,
         args: [Field; ARGS_COUNT]
     ) -> ([Field; RET_COUNT], u8) {
-        call_static(gas, contract_address, args, temporary_function_selector)
+        call_static(
+            gas_for_call(gas),
+            contract_address,
+            args,
+            temporary_function_selector
+        )
     }
 }
 
@@ -121,12 +135,11 @@ impl PublicContextInterface for AvmContext {
         self: &mut Self,
         contract_address: AztecAddress,
         temporary_function_selector: FunctionSelector,
-        args: [Field; ARGS_COUNT]
+        args: [Field; ARGS_COUNT],
+        gas_opts: GasOpts
     ) -> [Field; RETURN_VALUES_LENGTH] {
-        let gas = [/*l1_gas*/10000, /*l2_gas*/10000, /*da_gas*/10000];
-
         let results = call(
-            gas,
+            gas_for_call(gas_opts),
             contract_address,
             args,
             temporary_function_selector.to_field()
@@ -142,12 +155,11 @@ impl PublicContextInterface for AvmContext {
         self: &mut Self,
         contract_address: AztecAddress,
         temporary_function_selector: FunctionSelector,
-        args: [Field; ARGS_COUNT]
+        args: [Field; ARGS_COUNT],
+        gas_opts: GasOpts
     ) -> [Field; RETURN_VALUES_LENGTH] {
-        let gas = [/*l1_gas*/10000, /*l2_gas*/10000, /*da_gas*/10000];
-
         let (data_to_return, success): ([Field; RETURN_VALUES_LENGTH], u8) = call_static(
-            gas,
+            gas_for_call(gas_opts),
             contract_address,
             args,
             temporary_function_selector.to_field()
@@ -203,6 +215,15 @@ impl ContextInterface for AvmContext {
     }
 }
 
+// Helper functions
+fn gas_for_call(user_gas: GasOpts) -> [Field; 3] {
+    [
+        user_gas.l1_gas.unwrap_or_else(|| l1_gas_left()),
+        user_gas.l2_gas.unwrap_or_else(|| l2_gas_left() - NESTED_CALL_L2_GAS_BUFFER),
+        user_gas.da_gas.unwrap_or_else(|| da_gas_left())
+    ]
+}
+
 // AVM oracles (opcodes) follow, do not use directly.
 #[oracle(avmOpcodeAddress)]
 fn address() -> AztecAddress {}
@@ -240,6 +261,15 @@ fn block_number() -> Field {}
 #[oracle(avmOpcodeTimestamp)]
 fn timestamp() -> u64 {}
 
+#[oracle(avmOpcodeL1GasLeft)]
+fn l1_gas_left() -> Field {}
+
+#[oracle(avmOpcodeL2GasLeft)]
+fn l2_gas_left() -> Field {}
+
+#[oracle(avmOpcodeDaGasLeft)]
+fn da_gas_left() -> Field {}
+
 #[oracle(avmOpcodeNoteHashExists)]
 fn note_hash_exists(note_hash: Field, leaf_index: Field) -> u8 {}
 

noir-projects/aztec-nr/aztec/src/context/gas.nr

@@ -0,0 +1,15 @@
+struct GasOpts {
+  l1_gas: Option<Field>,
+  l2_gas: Option<Field>,
+  da_gas: Option<Field>,
+}
+
+impl GasOpts {
+    pub fn default() -> Self {
+        GasOpts { l1_gas: Option::none(), l2_gas: Option::none(), da_gas: Option::none() }
+    }
+
+    pub fn new(l1_gas: Field, l2_gas: Field, da_gas: Field) -> Self {
+        GasOpts { l1_gas: Option::some(l1_gas), l2_gas: Option::some(l2_gas), da_gas: Option::some(da_gas) }
+    }
+}

noir-projects/aztec-nr/aztec/src/context/interface.nr

@@ -3,6 +3,8 @@ use dep::protocol_types::{
     constants::RETURN_VALUES_LENGTH
 };
 
+use crate::context::gas::GasOpts;
+
 trait ContextInterface {
     fn push_new_note_hash(&mut self, note_hash: Field);
     fn push_new_nullifier(&mut self, nullifier: Field, nullified_commitment: Field);
@@ -34,13 +36,15 @@ trait PublicContextInterface {
         self: &mut Self,
         contract_address: AztecAddress,
         function_selector: FunctionSelector,
-        args: [Field; ARGS_COUNT]
+        args: [Field; ARGS_COUNT],
+        gas_opts: GasOpts
     ) -> [Field; RETURN_VALUES_LENGTH];
     fn static_call_public_function<ARGS_COUNT>(
         self: &mut Self,
         contract_address: AztecAddress,
         function_selector: FunctionSelector,
-        args: [Field; ARGS_COUNT]
+        args: [Field; ARGS_COUNT],
+        gas_opts: GasOpts
     ) -> [Field; RETURN_VALUES_LENGTH];
     fn delegate_call_public_function<ARGS_COUNT>(
         self: &mut Self,

noir-projects/aztec-nr/aztec/src/context/public_context.nr

@@ -1,5 +1,8 @@
 use crate::{
-    context::{inputs::PublicContextInputs, interface::ContextInterface, interface::PublicContextInterface},
+    context::{
+    inputs::PublicContextInputs, interface::ContextInterface, interface::PublicContextInterface,
+    gas::GasOpts
+},
     messaging::process_l1_to_l2_message,
     oracle::{arguments, public_call::call_public_function_internal}, hash::hash_args_array
 };
@@ -268,7 +271,8 @@ impl PublicContextInterface for PublicContext {
         self: &mut Self,
         contract_address: AztecAddress,
         function_selector: FunctionSelector,
-        args: [Field; ARGS_COUNT]
+        args: [Field; ARGS_COUNT],
+        _gas: GasOpts
     ) -> [Field; RETURN_VALUES_LENGTH] {
         let args_hash = hash_args_array(args);
         assert(args_hash == arguments::pack_arguments(args));
@@ -279,7 +283,8 @@ impl PublicContextInterface for PublicContext {
         self: &mut Self,
         contract_address: AztecAddress,
         function_selector: FunctionSelector,
-        args: [Field; ARGS_COUNT]
+        args: [Field; ARGS_COUNT],
+        _gas: GasOpts
     ) -> [Field; RETURN_VALUES_LENGTH] {
         let args_hash = hash_args_array(args);
         assert(args_hash == arguments::pack_arguments(args));

noir-projects/noir-contracts/contracts/avm_test_contract/src/main.nr

@@ -30,6 +30,7 @@ contract AvmTest {
         address::{AztecAddress, EthAddress}, constants::L1_TO_L2_MESSAGE_LENGTH,
         contract_instance::ContractInstance
     };
+    use dep::aztec::context::gas::GasOpts;
     use dep::aztec::oracle::get_contract_instance::{get_contract_instance_avm, get_contract_instance_internal_avm};
     use dep::aztec::protocol_types::abis::function_selector::FunctionSelector;
     use dep::aztec::protocol_types::traits::ToField;
@@ -340,12 +341,16 @@ contract AvmTest {
     #[aztec(public-vm)]
     fn raw_nested_call_to_add(arg_a: Field, arg_b: Field) -> pub Field {
         let selector = FunctionSelector::from_signature("add_args_return(Field,Field)").to_field();
-        let gas = [/*l1_gas*/10000, /*l2_gas*/10000, /*da_gas*/10000];
 
         // Nested call
-        let results = context.call_public_function_raw(gas, context.this_address(), selector, [arg_a, arg_b]);
+        let results = context.call_public_function_raw(
+            GasOpts::default(),
+            context.this_address(),
+            selector,
+            [arg_a, arg_b]
+        );
         let data_to_return: [Field; 1] = results.0;
-        // this explicit size   ^ is necessary to ensure that ret_size is compile-time
+        // this explicit size is necessary to ensure that ret_size is compile-time
         // (ensure the data_to_return is in a HeapArray not a HeapVector)
         let success: u8 = results.1;
 
@@ -355,14 +360,46 @@ contract AvmTest {
         add_result
     }
 
+    // Directly call the external call opcode to initiate a nested call to the add function with user-specified gas
+    #[aztec(public-vm)]
+    fn raw_nested_call_to_add_with_gas(
+        arg_a: Field,
+        arg_b: Field,
+        l1_gas: Field,
+        l2_gas: Field,
+        da_gas: Field
+    ) -> pub Field {
+        let selector = FunctionSelector::from_signature("add_args_return(Field,Field)").to_field();
+
+        // Nested call
+        let results = context.call_public_function_raw(
+            GasOpts::new(l1_gas, l2_gas, da_gas),
+            context.this_address(),
+            selector,
+            [arg_a, arg_b]
+        );
+        let data_to_return: [Field; 1] = results.0;
+        // this explicit size is necessary to ensure that ret_size is compile-time
+        // (ensure the data_to_return is in a HeapArray not a HeapVector)
+        let success: u8 = results.1;
+
+        let add_result = data_to_return[0];
+        add_result
+    }
+
     // Use the `call_public_function` wrapper to initiate a nested call to the add function
     #[aztec(public-vm)]
     fn nested_call_to_add(arg_a: Field, arg_b: Field) -> pub Field {
         let selector = FunctionSelector::from_signature("add_args_return(Field,Field)");
 
         // Nested call using standard context interface function
-        let data_to_return: [Field; RETURN_VALUES_LENGTH] = context.call_public_function(context.this_address(), selector, [arg_a, arg_b]);
-        // this explicit size   ^ is necessary to ensure that ret_size is compile-time
+        let data_to_return: [Field; RETURN_VALUES_LENGTH] = context.call_public_function(
+            context.this_address(),
+            selector,
+            [arg_a, arg_b],
+            GasOpts::default()
+        );
+        // this explicit size in the return variable is necessary to ensure that ret_size is compile-time
         // (ensure the data_to_return is in a HeapArray not a HeapVector)
 
         let add_result = data_to_return[0];
@@ -373,9 +410,13 @@ contract AvmTest {
     #[aztec(public-vm)]
     fn raw_nested_static_call_to_add(arg_a: Field, arg_b: Field) -> pub (Field, u8) {
         let selector = FunctionSelector::from_signature("add_args_return(Field,Field)").to_field();
-        let gas = [/*l1_gas*/10000, /*l2_gas*/10000, /*da_gas*/10000];
 
-        let (result_data, success): ([Field; 1], u8) = context.static_call_public_function_raw(gas, context.this_address(), selector, [arg_a, arg_b]);
+        let (result_data, success): ([Field; 1], u8) = context.static_call_public_function_raw(
+            GasOpts::default(),
+            context.this_address(),
+            selector,
+            [arg_a, arg_b]
+        );
 
         (result_data[0], success)
     }
@@ -384,10 +425,9 @@ contract AvmTest {
     #[aztec(public-vm)]
     fn raw_nested_static_call_to_set_storage() -> pub u8 {
         let selector = FunctionSelector::from_signature("set_storage_single(Field)").to_field();
-        let gas = [/*l1_gas*/10000, /*l2_gas*/10000, /*da_gas*/10000];
         let calldata: [Field; 1] = [20];
 
-        let (_data_to_return, success): ([Field; 0], u8) = context.static_call_public_function_raw(gas, context.this_address(), selector, calldata);
+        let (_data_to_return, success): ([Field; 0], u8) = context.static_call_public_function_raw(GasOpts::default(), context.this_address(), selector, calldata);
 
         success
     }
@@ -397,7 +437,12 @@ contract AvmTest {
     fn nested_static_call_to_add(arg_a: Field, arg_b: Field) -> pub Field {
         let selector = FunctionSelector::from_signature("add_args_return(Field,Field)");
 
-        let result_data: [Field; RETURN_VALUES_LENGTH] = context.static_call_public_function(context.this_address(), selector, [arg_a, arg_b]);
+        let result_data: [Field; RETURN_VALUES_LENGTH] = context.static_call_public_function(
+            context.this_address(),
+            selector,
+            [arg_a, arg_b],
+            GasOpts::default()
+        );
 
         result_data[0]
     }
@@ -408,6 +453,6 @@ contract AvmTest {
         let selector = FunctionSelector::from_signature("set_storage_single(Field)");
         let calldata: [Field; 1] = [20];
 
-        let _resultData: [Field; RETURN_VALUES_LENGTH] = context.static_call_public_function(context.this_address(), selector, calldata);
+        let _resultData: [Field; RETURN_VALUES_LENGTH] = context.static_call_public_function(context.this_address(), selector, calldata, GasOpts::default());
     }
 }

noir-projects/noir-contracts/contracts/benchmarking_contract/src/main.nr

@@ -10,7 +10,7 @@ contract Benchmarking {
     };
     use dep::value_note::{utils::{increment, decrement}, value_note::ValueNote};
 
-    use dep::aztec::{context::Context};
+    use dep::aztec::{context::{Context, gas::GasOpts}};
 
     #[aztec(storage)]
     struct Storage {
@@ -47,7 +47,8 @@ contract Benchmarking {
         let _callStackItem1 = context.call_public_function(
             context.this_address(),
             FunctionSelector::from_signature("broadcast((Field))"),
-            [owner.to_field()]
+            [owner.to_field()],
+            GasOpts::default()
         );
     }