div by const

Author: ChihChengLiang

zkevm-circuits/src/evm_circuit/execution/callop.rs

@@ -271,7 +271,7 @@ impl<F: Field> ExecutionGadget<F> for CallOpGadget<F> {
         let gas_cost = call_gadget.gas_cost_expr(is_warm_prev.expr(), is_call.expr());
         // Apply EIP 150
         let gas_available = cb.curr.state.gas_left.expr() - gas_cost.clone();
-        let one_64th_gas = ConstantDivisionGadget::construct(cb, gas_available.clone(), 64);
+        let one_64th_gas = cb.div_by_const(gas_available.clone(), 64);
         let all_but_one_64th_gas = gas_available - one_64th_gas.quotient();
         let capped_callee_gas_left =
             cb.min_max(call_gadget.gas_expr(), all_but_one_64th_gas.clone());
@@ -476,8 +476,8 @@ impl<F: Field> ExecutionGadget<F> for CallOpGadget<F> {
                 let callee_gas_left = callee_gas_left.expr()
                     + call_gadget.has_value.clone() * GAS_STIPEND_CALL_WITH_VALUE.expr();
 
-                let precompile_output_word_size_div: ConstantDivisionGadget<F, N_BYTES_U64> =
-                    ConstantDivisionGadget::construct(cb, precompile_output_rws.expr(), 32);
+                let precompile_output_word_size_div =
+                    cb.div_by_const(precompile_output_rws.expr(), 32);
                 let precompile_output_word_size_div_remainder_zero =
                     cb.is_zero(precompile_output_word_size_div.remainder());
                 let precompile_output_word_size = precompile_output_word_size_div.quotient()

zkevm-circuits/src/evm_circuit/execution/create.rs

@@ -168,7 +168,7 @@ impl<F: Field, const IS_CREATE2: bool, const S: ExecutionState> ExecutionGadget<
             );
         let gas_cost = GasCost::CREATE.expr() + memory_expansion.gas_cost() + keccak_gas_cost;
         let gas_remaining = cb.curr.state.gas_left.expr() - gas_cost.clone();
-        let gas_left = ConstantDivisionGadget::construct(cb, gas_remaining.clone(), 64);
+        let gas_left = cb.div_by_const(gas_remaining.clone(), 64);
         let callee_gas_left = gas_remaining - gas_left.quotient();
 
         let was_warm = cb.query_bool();

zkevm-circuits/src/evm_circuit/util/constraint_builder.rs

@@ -1,7 +1,7 @@
 use super::{
     math_gadget::{
-        IsEqualGadget, IsEqualWordGadget, IsZeroGadget, IsZeroWordGadget, LtGadget, LtWordGadget,
-        MinMaxGadget,
+        ConstantDivisionGadget, IsEqualGadget, IsEqualWordGadget, IsZeroGadget, IsZeroWordGadget,
+        LtGadget, LtWordGadget, MinMaxGadget,
     },
     rlc, AccountAddress, CachedRegion, CellType, MemoryAddress, StoredExpression, U64Cell,
 };
@@ -586,18 +586,6 @@ impl<'a, F: Field> EVMConstraintBuilder<'a, F> {
 
     // Math gadgets
 
-    // abs_word
-    // add_word
-    // binary_number
-    // byte_size
-    // cmp_words
-    // comparison
-    // constant_division
-    // modulo
-    // mul_add_words
-    // mul_add_words512
-    // mul_word_u64
-
     pub(crate) fn is_zero(&mut self, value: Expression<F>) -> IsZeroGadget<F> {
         IsZeroGadget::construct(self, value)
     }
@@ -642,6 +630,14 @@ impl<'a, F: Field> EVMConstraintBuilder<'a, F> {
         MinMaxGadget::construct(self, lhs, rhs)
     }
 
+    pub(crate) fn div_by_const<const N_BYTES: usize>(
+        &mut self,
+        numerator: Expression<F>,
+        denominator: u64,
+    ) -> ConstantDivisionGadget<F, N_BYTES> {
+        ConstantDivisionGadget::construct(self, numerator, denominator)
+    }
+
     // Fixed
 
     pub(crate) fn range_lookup(&mut self, value: Expression<F>, range: u64) {

zkevm-circuits/src/evm_circuit/util/memory_gadget.rs

@@ -339,7 +339,7 @@ pub(crate) struct MemoryWordSizeGadget<F> {
 
 impl<F: Field> MemoryWordSizeGadget<F> {
     pub(crate) fn construct(cb: &mut EVMConstraintBuilder<F>, address: Expression<F>) -> Self {
-        let memory_word_size = ConstantDivisionGadget::construct(cb, address + 31.expr(), 32);
+        let memory_word_size = cb.div_by_const(address + 31.expr(), 32);
 
         Self { memory_word_size }
     }

zkevm-circuits/src/evm_circuit/util/tx.rs

@@ -240,8 +240,7 @@ impl<F: Field> TxDataGadget<F> {
         // Calculate transaction gas fee
         let mul_gas_fee_by_gas = MulWordByU64Gadget::construct(cb, gas_price.clone(), gas.expr());
 
-        let call_data_word_length =
-            ConstantDivisionGadget::construct(cb, call_data_length.expr() + 31.expr(), 32);
+        let call_data_word_length = cb.div_by_const(call_data_length.expr() + 31.expr(), 32);
 
         let (cost_sum, gas_mul_gas_price_plus_value) = if calculate_total_cost {
             let cost_sum = cb.query_word32();