chore(avm): Gas alignments with simulator (#6873)

Resolves #6860

barretenberg/cpp/pil/avm/avm_main.pil

@@ -426,7 +426,7 @@ namespace avm_main(256);
 
     //===== CONTROL_FLOW_CONSISTENCY ============================================
     pol INTERNAL_CALL_STACK_SELECTORS = (first + sel_internal_call + sel_internal_return + sel_halt);
-    pol ALL_CTRL_FLOW_SEL = sel_jump + sel_jumpi + sel_internal_call + sel_internal_return + sel_external_call;
+    pol ALL_CTRL_FLOW_SEL = sel_jump + sel_jumpi + sel_internal_call + sel_internal_return;
 
     pol ALL_BINARY_SEL = sel_op_and + sel_op_or + sel_op_xor;
     pol ALL_GADGET_SEL = sel_op_radix_le + sel_op_sha256 + sel_op_poseidon2 + sel_op_keccak + sel_op_pedersen;
@@ -439,6 +439,7 @@ namespace avm_main(256);
     //       setting a newly introduced boolean mem_op_activate_gas which is set in witness generation.
     //       We should remove this shortcut and constrain this activation through bytecode decomposition.
     //       Alternatively, we introduce a boolean selector for the three opcodes mentioned above.
+    //       Note: External call gas cost is not constrained
     pol commit gas_cost_active;
     pol commit mem_op_activate_gas; // TODO: remove this one
     gas_cost_active - OPCODE_SELECTORS - ALL_CTRL_FLOW_SEL - mem_op_activate_gas = 0;

barretenberg/cpp/src/barretenberg/relations/generated/avm/avm_main.hpp

@@ -1060,9 +1060,8 @@ template <typename FF_> class avm_mainImpl {
                        avm_main_sel_op_emit_l2_to_l1_msg) +
                       avm_main_sel_op_sload) +
                      avm_main_sel_op_sstore))) -
-                  ((((avm_main_sel_jump + avm_main_sel_jumpi) + avm_main_sel_internal_call) +
-                    avm_main_sel_internal_return) +
-                   avm_main_sel_external_call)) -
+                  (((avm_main_sel_jump + avm_main_sel_jumpi) + avm_main_sel_internal_call) +
+                   avm_main_sel_internal_return)) -
                  avm_main_mem_op_activate_gas);
             tmp *= scaling_factor;
             std::get<89>(evals) += tmp;

barretenberg/cpp/src/barretenberg/vm/avm_trace/avm_gas_trace.cpp

@@ -1,4 +1,5 @@
 #include "barretenberg/vm/avm_trace/avm_gas_trace.hpp"
+#include "barretenberg/vm/avm_trace/avm_opcode.hpp"
 
 namespace bb::avm_trace {
 
@@ -50,4 +51,29 @@ void AvmGasTraceBuilder::constrain_gas_lookup(uint32_t clk, OpCode opcode)
     gas_trace.push_back(entry);
 }
 
+void AvmGasTraceBuilder::constrain_gas_for_external_call(uint32_t clk)
+{
+    // Arbitrary constants for the moment
+    uint32_t l2_gas_cost = 6;  // This will be hinted
+    uint32_t da_gas_cost = 23; // This will be hinted
+
+    remaining_l2_gas -= l2_gas_cost;
+    remaining_da_gas -= da_gas_cost;
+
+    // Decrease the gas left
+    // Create a gas trace entry
+    GasTraceEntry entry = {
+        .clk = clk,
+        .opcode = OpCode::CALL,
+        .l2_gas_cost = 0, // We need 0 in this case because we do not activate the gas_cost_active selector to satisfy
+                          // #[L2_GAS_INACTIVE].
+        .da_gas_cost = 0, // We need 0 in this case because we do not activate the gas_cost_active selector to satisfy
+                          // #[DA_GAS_INACTIVE].
+        .remaining_l2_gas = remaining_l2_gas,
+        .remaining_da_gas = remaining_da_gas,
+    };
+
+    gas_trace.push_back(entry);
+}
+
 } // namespace bb::avm_trace

barretenberg/cpp/src/barretenberg/vm/avm_trace/avm_gas_trace.hpp

@@ -1,5 +1,6 @@
 #include "barretenberg/vm/avm_trace/avm_common.hpp"
 #include "barretenberg/vm/avm_trace/avm_opcode.hpp"
+#include <cstdint>
 
 namespace bb::avm_trace {
 
@@ -129,6 +130,7 @@ class AvmGasTraceBuilder {
     std::vector<GasTraceEntry> finalize();
 
     void constrain_gas_lookup(uint32_t clk, OpCode opcode);
+    void constrain_gas_for_external_call(uint32_t clk);
     void set_initial_gas(uint32_t l2_gas, uint32_t da_gas);
 
     std::vector<GasTraceEntry> gas_trace;

barretenberg/cpp/src/barretenberg/vm/avm_trace/avm_trace.cpp

@@ -47,6 +47,13 @@ void AvmTraceBuilder::reset()
     alu_trace_builder.reset();
     bin_trace_builder.reset();
     kernel_trace_builder.reset();
+    gas_trace_builder.reset();
+    conversion_trace_builder.reset();
+    sha256_trace_builder.reset();
+    poseidon2_trace_builder.reset();
+    keccak_trace_builder.reset();
+    pedersen_trace_builder.reset();
+
     return_data_counter = 0;
 }
 
@@ -1822,8 +1829,10 @@ void AvmTraceBuilder::calldata_copy(
                 call_ptr, clk, IntermRegister::IC, mem_idx_c, ic, AvmMemoryTag::U0, AvmMemoryTag::FF);
         }
 
-        // Constrain gas cost
-        gas_trace_builder.constrain_gas_lookup(clk, OpCode::CALLDATACOPY);
+        // Constrain gas cost on the first row
+        if (pos == 0) {
+            gas_trace_builder.constrain_gas_lookup(clk, OpCode::CALLDATACOPY);
+        }
 
         main_trace.push_back(Row{
             .avm_main_clk = clk,
@@ -1838,7 +1847,8 @@ void AvmTraceBuilder::calldata_copy(
             .avm_main_mem_idx_b = FF(mem_idx_b),
             .avm_main_mem_idx_c = FF(mem_idx_c),
             .avm_main_mem_op_a = FF(mem_op_a),
-            .avm_main_mem_op_activate_gas = FF(1), // TODO: remove in the long term
+            .avm_main_mem_op_activate_gas = FF(static_cast<uint32_t>(
+                pos == 0)), // TODO: remove in the long term. This activate gas only for the first row.
             .avm_main_mem_op_b = FF(mem_op_b),
             .avm_main_mem_op_c = FF(mem_op_c),
             .avm_main_pc = FF(pc++),
@@ -1946,8 +1956,10 @@ std::vector<FF> AvmTraceBuilder::return_op(uint8_t indirect, uint32_t ret_offset
             returnMem.push_back(ic);
         }
 
-        // Constrain gas cost
-        gas_trace_builder.constrain_gas_lookup(clk, OpCode::RETURN);
+        // Constrain gas cost on the first row
+        if (pos == 0) {
+            gas_trace_builder.constrain_gas_lookup(clk, OpCode::RETURN);
+        }
 
         main_trace.push_back(Row{
             .avm_main_clk = clk,
@@ -1962,7 +1974,8 @@ std::vector<FF> AvmTraceBuilder::return_op(uint8_t indirect, uint32_t ret_offset
             .avm_main_mem_idx_b = FF(mem_idx_b),
             .avm_main_mem_idx_c = FF(mem_idx_c),
             .avm_main_mem_op_a = FF(mem_op_a),
-            .avm_main_mem_op_activate_gas = FF(1), // TODO: remove in the long term
+            .avm_main_mem_op_activate_gas = FF(static_cast<uint32_t>(
+                pos == 0)), // TODO: remove in the long term. This activate gas only for the first row.
             .avm_main_mem_op_b = FF(mem_op_b),
             .avm_main_mem_op_c = FF(mem_op_c),
             .avm_main_pc = FF(pc),
@@ -2339,7 +2352,7 @@ void AvmTraceBuilder::op_call([[maybe_unused]] uint8_t indirect,
     // We can load up to 4 things per row
     auto register_order = std::array{ IntermRegister::IA, IntermRegister::IB, IntermRegister::IC, IntermRegister::ID };
     // Constrain gas cost
-    gas_trace_builder.constrain_gas_lookup(clk, OpCode::CALL);
+    gas_trace_builder.constrain_gas_for_external_call(clk);
     // Indirect is ZEROTH, SECOND and FOURTH bit  COME BACK TO MAKING THIS ALL SUPPORTED
     auto read_ind_gas_offset =
         mem_trace_builder.indirect_read_and_load_from_memory(call_ptr, clk, IndirectRegister::IND_A, gas_offset);
@@ -3921,15 +3934,19 @@ std::vector<Row> AvmTraceBuilder::finalize(uint32_t min_trace_size, bool range_c
 
         auto& dest = main_trace.at(gas_entry.clk);
         auto& next = main_trace.at(gas_entry.clk + 1);
-        dest.avm_main_gas_cost_active = FF(1);
+
+        // TODO: gas is not constrained for external call at this time
+        if (gas_entry.opcode != OpCode::CALL) {
+            dest.avm_main_gas_cost_active = FF(1);
+        }
 
         // Write each of the relevant gas accounting values
         dest.avm_main_opcode_val = static_cast<uint8_t>(gas_entry.opcode);
         dest.avm_main_l2_gas_op = gas_entry.l2_gas_cost;
         dest.avm_main_da_gas_op = gas_entry.da_gas_cost;
 
-        current_l2_gas_remaining -= gas_entry.l2_gas_cost;
-        current_da_gas_remaining -= gas_entry.da_gas_cost;
+        current_l2_gas_remaining = gas_entry.remaining_l2_gas;
+        current_da_gas_remaining = gas_entry.remaining_da_gas;
         next.avm_main_l2_gas_remaining = current_l2_gas_remaining;
         next.avm_main_da_gas_remaining = current_da_gas_remaining;
 

barretenberg/cpp/src/barretenberg/vm/tests/avm_arithmetic.test.cpp

@@ -1,6 +1,7 @@
 #include "avm_common.test.hpp"
 #include "barretenberg/numeric/uint128/uint128.hpp"
 #include "barretenberg/vm/avm_trace/avm_common.hpp"
+#include "barretenberg/vm/avm_trace/avm_helper.hpp"
 #include "barretenberg/vm/avm_trace/avm_trace.hpp"
 #include "barretenberg/vm/tests/helpers.test.hpp"
 #include <array>
@@ -1893,7 +1894,7 @@ TEST_F(AvmArithmeticNegativeTestsFF, operationWithErrorFlag)
 
     EXPECT_THROW_WITH_MESSAGE(validate_trace_check_circuit(std::move(trace)), "SUBOP_ERROR_RELEVANT_OP");
 
-    trace_builder.reset();
+    trace_builder = AvmTraceBuilder(public_inputs);
 
     trace_builder.calldata_copy(0, 0, 3, 0, std::vector<FF>{ 8, 4, 17 });
 
@@ -1910,7 +1911,7 @@ TEST_F(AvmArithmeticNegativeTestsFF, operationWithErrorFlag)
 
     EXPECT_THROW_WITH_MESSAGE(validate_trace_check_circuit(std::move(trace)), "SUBOP_ERROR_RELEVANT_OP");
 
-    trace_builder.reset();
+    trace_builder = AvmTraceBuilder(public_inputs);
 
     trace_builder.calldata_copy(0, 0, 3, 0, std::vector<FF>{ 5, 0, 20 });