optimize few subcircuit synthesis call phase from 3->2 in dev mode (#1517)

### Description

Remove evm_word challenge and optimize from 3->2 phase in dev phase.

### Issue Link


#1516

### Type of change

- [x] Breaking change (fix or feature that would cause existing
functionality to not work as expected)

Author: hero78119

zkevm-circuits/src/evm_circuit/execution.rs

@@ -1344,11 +1344,9 @@ impl<F: Field> ExecutionConfig<F> {
         block: &Block<F>,
         challenges: &Challenges<Value<F>>,
     ) {
-        let mut evm_randomness = F::ZERO;
-        challenges.evm_word().map(|v| evm_randomness = v);
         let mut lookup_randomness = F::ZERO;
         challenges.lookup_input().map(|v| lookup_randomness = v);
-        if evm_randomness.is_zero_vartime() || lookup_randomness.is_zero_vartime() {
+        if lookup_randomness.is_zero_vartime() {
             // challenges not ready
             return;
         }

zkevm-circuits/src/evm_circuit/param.rs

@@ -16,7 +16,7 @@ pub const MAX_STEP_HEIGHT: usize = 19;
 pub(crate) const STEP_STATE_HEIGHT: usize = 1;
 
 /// Number of Advice Phase2 columns in the EVM circuit
-pub const N_PHASE2_COLUMNS: usize = 4;
+pub const N_PHASE2_COLUMNS: usize = 1;
 
 /// Number of Advice Phase1 columns in the EVM circuit
 pub const N_PHASE1_COLUMNS: usize =

zkevm-circuits/src/evm_circuit/util.rs

@@ -13,7 +13,7 @@ use crate::{
     util::{cell_manager::CMFixedWidthStrategyDistribution, int_decomposition::IntDecomposition},
     witness::{Block, ExecStep, Rw, RwMap},
 };
-use eth_types::{Address, Field, ToLittleEndian, U256};
+use eth_types::{Address, Field, U256};
 use halo2_proofs::{
     circuit::{AssignedCell, Region, Value},
     plonk::{Advice, Assigned, Column, ConstraintSystem, Error, Expression},
@@ -138,12 +138,6 @@ impl<'r, 'b, F: Field> CachedRegion<'r, 'b, F> {
         self.challenges
     }
 
-    pub fn word_rlc(&self, n: U256) -> Value<F> {
-        self.challenges
-            .evm_word()
-            .map(|r| rlc::value(&n.to_le_bytes(), r))
-    }
-
     pub fn keccak_rlc(&self, le_bytes: &[u8]) -> Value<F> {
         self.challenges
             .keccak_input()

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

@@ -556,10 +556,6 @@ impl<'a, F: Field> EVMConstraintBuilder<'a, F> {
         .query_cells(self.meta, cell_type, count)
     }
 
-    pub(crate) fn word_rlc<const N: usize>(&self, bytes: [Expression<F>; N]) -> Expression<F> {
-        rlc::expr(&bytes, self.challenges.evm_word())
-    }
-
     pub(crate) fn keccak_rlc<const N: usize>(&self, bytes: [Expression<F>; N]) -> Expression<F> {
         rlc::expr(&bytes, self.challenges.keccak_input())
     }

zkevm-circuits/src/super_circuit.rs

@@ -144,7 +144,6 @@ impl<F: Field> SubCircuitConfig<F> for SuperCircuitConfig<F> {
         let challenges = Challenges::mock(
             power_of_randomness[0].clone(),
             power_of_randomness[0].clone(),
-            power_of_randomness[0].clone(),
         );
 
         let keccak_circuit = KeccakCircuitConfig::new(
@@ -429,7 +428,6 @@ impl<F: Field> Circuit<F> for SuperCircuit<F> {
         let challenges = Challenges::mock(
             Value::known(block.randomness),
             Value::known(block.randomness),
-            Value::known(block.randomness),
         );
         let rws = &self.state_circuit.rows;
 

zkevm-circuits/src/util.rs

@@ -41,7 +41,6 @@ pub(crate) fn random_linear_combine_word<F: Field>(bytes: [u8; 32], randomness:
 /// All challenges used in `SuperCircuit`.
 #[derive(Default, Clone, Copy, Debug)]
 pub struct Challenges<T = Challenge> {
-    evm_word: T,
     keccak_input: T,
     lookup_input: T,
 }
@@ -50,27 +49,20 @@ impl Challenges {
     /// Construct `Challenges` by allocating challenges in specific phases.
     pub fn construct<F: Field>(meta: &mut ConstraintSystem<F>) -> Self {
         #[cfg(any(feature = "test", test, feature = "test-circuits"))]
-        let _dummy_cols = [
-            meta.advice_column(),
-            meta.advice_column_in(SecondPhase),
-            meta.advice_column_in(halo2_proofs::plonk::ThirdPhase),
-        ];
+        let _dummy_cols = [meta.advice_column(), meta.advice_column_in(SecondPhase)];
 
         Self {
-            evm_word: meta.challenge_usable_after(FirstPhase),
             keccak_input: meta.challenge_usable_after(FirstPhase),
             lookup_input: meta.challenge_usable_after(SecondPhase),
         }
     }
 
     /// Returns `Expression` of challenges from `ConstraintSystem`.
     pub fn exprs<F: Field>(&self, meta: &mut ConstraintSystem<F>) -> Challenges<Expression<F>> {
-        let [evm_word, keccak_input, lookup_input] = query_expression(meta, |meta| {
-            [self.evm_word, self.keccak_input, self.lookup_input]
-                .map(|challenge| meta.query_challenge(challenge))
+        let [keccak_input, lookup_input] = query_expression(meta, |meta| {
+            [self.keccak_input, self.lookup_input].map(|challenge| meta.query_challenge(challenge))
         });
         Challenges {
-            evm_word,
             keccak_input,
             lookup_input,
         }
@@ -79,19 +71,13 @@ impl Challenges {
     /// Returns `Value` of challenges from `Layouter`.
     pub fn values<F: Field>(&self, layouter: &mut impl Layouter<F>) -> Challenges<Value<F>> {
         Challenges {
-            evm_word: layouter.get_challenge(self.evm_word),
             keccak_input: layouter.get_challenge(self.keccak_input),
             lookup_input: layouter.get_challenge(self.lookup_input),
         }
     }
 }
 
 impl<T: Clone> Challenges<T> {
-    /// Returns challenge of `evm_word`.
-    pub fn evm_word(&self) -> T {
-        self.evm_word.clone()
-    }
-
     /// Returns challenge of `keccak_input`.
     pub fn keccak_input(&self) -> T {
         self.keccak_input.clone()
@@ -103,13 +89,12 @@ impl<T: Clone> Challenges<T> {
     }
 
     /// Returns the challenges indexed by the challenge index
-    pub fn indexed(&self) -> [&T; 3] {
-        [&self.evm_word, &self.keccak_input, &self.lookup_input]
+    pub fn indexed(&self) -> [&T; 2] {
+        [&self.keccak_input, &self.lookup_input]
     }
 
-    pub(crate) fn mock(evm_word: T, keccak_input: T, lookup_input: T) -> Self {
+    pub(crate) fn mock(keccak_input: T, lookup_input: T) -> Self {
         Self {
-            evm_word,
             keccak_input,
             lookup_input,
         }
@@ -128,11 +113,6 @@ impl<F: Field> Challenges<Expression<F>> {
         .unwrap()
     }
 
-    /// Returns powers of randomness for word RLC encoding
-    pub fn evm_word_powers_of_randomness<const S: usize>(&self) -> [Expression<F>; S] {
-        Self::powers_of(self.evm_word.clone())
-    }
-
     /// Returns powers of randomness for keccak circuit's input
     pub fn keccak_powers_of_randomness<const S: usize>(&self) -> [Expression<F>; S] {
         Self::powers_of(self.keccak_input.clone())