fix(bench): dedupe merged BAL storage reads

bin/reth-bench/src/bench/generate_big_block.rs

@@ -29,7 +29,10 @@ use reth_ethereum_cli::chainspec::EthereumChainSpecParser;
 use reth_ethereum_primitives::Receipt;
 use reth_primitives_traits::proofs;
 use serde::{Deserialize, Serialize};
-use std::{collections::HashMap, future::Future};
+use std::{
+    collections::{HashMap, HashSet},
+    future::Future,
+};
 use tracing::{info, warn};
 
 use crate::bench::helpers::fetch_block_access_list;
@@ -717,6 +720,17 @@ fn merge_account_changes(existing: &mut AccountChanges, incoming: AccountChanges
     existing.balance_changes.extend(incoming.balance_changes);
     existing.nonce_changes.extend(incoming.nonce_changes);
     existing.code_changes.extend(incoming.code_changes);
+
+    // EIP-7928 invariant: a slot must appear in either storage_changes or storage_reads,
+    // not both. Per-block BALs respect this, but merging blocks can produce a slot
+    // that is read in one block and changed in another. Without this normalization,
+    // an empty read entry can shadow the real writes during BAL deserialization,
+    // making reads of that slot fall through to stale snapshot state.
+    let written: HashSet<_> =
+        existing.storage_changes.iter().map(|slot_changes| slot_changes.slot).collect();
+    existing.storage_reads.retain(|slot| !written.contains(slot));
+    let mut seen = HashSet::with_capacity(existing.storage_reads.len());
+    existing.storage_reads.retain(|slot| seen.insert(*slot));
 }
 
 fn merge_slot_changes(existing: &mut Vec<SlotChanges>, incoming: Vec<SlotChanges>) {
@@ -836,4 +850,54 @@ mod tests {
         assert_eq!(other.address, Address::repeat_byte(0x22));
         assert_eq!(other.storage_changes[0].changes[0].block_access_index, 3);
     }
+
+    #[test]
+    fn merge_account_changes_normalizes_storage_reads_after_cross_block_merge() {
+        let address = Address::repeat_byte(0x33);
+        const A: U256 = U256::from_limbs([1, 0, 0, 0]);
+        const B: U256 = U256::from_limbs([2, 0, 0, 0]);
+        const C: U256 = U256::from_limbs([3, 0, 0, 0]);
+        const D: U256 = U256::from_limbs([4, 0, 0, 0]);
+
+        // Each AccountChanges value is valid on its own: storage slots only appear in
+        // either reads or changes. The invalid read/change overlap is introduced when
+        // these per-block BAL entries are merged for a standalone big block.
+        let mut existing = AccountChanges {
+            address,
+            storage_changes: vec![SlotChanges::new(A, vec![StorageChange::new(0, U256::from(10))])],
+            storage_reads: vec![B, C],
+            balance_changes: vec![],
+            nonce_changes: vec![],
+            code_changes: vec![],
+        };
+
+        // B is read before it is written by the incoming block, and A is written before
+        // it appears as a read in the incoming block. C is read in both blocks, so the
+        // merge should also dedupe it. D remains read-only.
+        let incoming = AccountChanges {
+            address,
+            storage_changes: vec![SlotChanges::new(B, vec![StorageChange::new(1, U256::from(20))])],
+            storage_reads: vec![A, C, D],
+            balance_changes: vec![],
+            nonce_changes: vec![],
+            code_changes: vec![],
+        };
+
+        merge_account_changes(&mut existing, incoming);
+
+        // Written slots remain represented by storage_changes, while storage_reads only
+        // keeps unique read-only slots in first-seen order.
+        assert_eq!(
+            existing
+                .storage_changes
+                .iter()
+                .map(|slot_changes| slot_changes.slot)
+                .collect::<Vec<_>>(),
+            vec![A, B]
+        );
+        assert_eq!(existing.storage_reads, vec![C, D]);
+        assert!(existing.storage_reads.iter().all(|read_slot| {
+            !existing.storage_changes.iter().any(|slot_changes| slot_changes.slot == *read_slot)
+        }));
+    }
 }