MultiOffRamp - size optimizations (#991)

## Motivation
Optimizes the contract size for the merged MultiOffRamp + CommitStore to
be able to fit the deployment size limits

## Solution
Currently the margin is at -0.972KB with 3600 optimizer runs. The
contract size fits the space with 1800 optimizer runs.

The contract size can further be reduced, and the optimizer runs
increased after the Nonce Manager is integrated into the MultiOffRamp

Each optimization is split into a separate commit. Complete list:
* Remove in-depth message validations -> these will be moved off-chain
(ticket already created)
* Move `isCursed` to shared internal function
* Move forked chain check, curse check and source config enabled check
to common internal function
* ~~Move source chain config + curse check to single shared function
(used in both exec & commit)~~
* ~~Move zero address check to internal lib~~
* Remove global pausing from the multi-offramp -> there are 4
alternative methods of achieving pausing:
* Per-lane: using `IMessageValidator` (execution-only), disabling the
source chain config, cursing the lane via RMN
  * Globally: implementing the global pause in the RMN
  * The savings are significant, at around ~0.8KB
* Split StaticConfig and DynamicConfig set events
* Get rid of `Any2EVMMessageRoute` and use 2 internal functions to solve
stack depth (same as the OffRamp changes)
* Other contract size golfing: variable caching, inlining
* Compile with lower optimizer runs for the multi-offramp
* **Update**: OCR3 no longer needs a `uniqueReports` distinction
* **Other fix**: OCR3 now uses sequenceNumbers

contracts/.changeset/gentle-spoons-vanish.md

@@ -0,0 +1,5 @@
+---
+'@chainlink/contracts-ccip': minor
+---
+
+#changed MultiOffRamp contract size optimizations

contracts/scripts/native_solc_compile_all_ccip

@@ -10,6 +10,7 @@ SOLC_VERSION="0.8.24"
 OPTIMIZE_RUNS=26000
 OPTIMIZE_RUNS_OFFRAMP=18000
 OPTIMIZE_RUNS_ONRAMP=3600
+OPTIMIZE_RUNS_MULTI_OFFRAMP=1800
 
 
 SCRIPTPATH="$( cd "$(dirname "$0")" >/dev/null 2>&1 ; pwd -P )"
@@ -27,10 +28,14 @@ compileContract () {
   local optimize_runs=$OPTIMIZE_RUNS
 
   case $1 in
-    "ccip/offRamp/EVM2EVMOffRamp.sol" | "ccip/offRamp/EVM2EVMMultiOffRamp.sol")
+    "ccip/offRamp/EVM2EVMOffRamp.sol")
     echo "OffRamp uses $OPTIMIZE_RUNS_OFFRAMP optimizer runs."
       optimize_runs=$OPTIMIZE_RUNS_OFFRAMP
       ;;
+    "ccip/offRamp/EVM2EVMMultiOffRamp.sol")
+    echo "MultiOffRamp uses $OPTIMIZE_RUNS_MULTI_OFFRAMP optimizer runs."
+      optimize_runs=$OPTIMIZE_RUNS_MULTI_OFFRAMP
+      ;;
     "ccip/onRamp/EVM2EVMMultiOnRamp.sol" | "ccip/onRamp/EVM2EVMOnRamp.sol")
     echo "OnRamp uses $OPTIMIZE_RUNS_ONRAMP optimizer runs."
       optimize_runs=$OPTIMIZE_RUNS_ONRAMP

contracts/src/v0.8/ccip/ocr/MultiOCR3Base.sol

@@ -4,7 +4,6 @@ pragma solidity ^0.8.0;
 import {OwnerIsCreator} from "../../shared/access/OwnerIsCreator.sol";
 import {ITypeAndVersion} from "../../shared/interfaces/ITypeAndVersion.sol";
 
-// TODO: consider splitting configs & verification logic off to auth library (if size is prohibitive)
 /// @notice Onchain verification of reports from the offchain reporting protocol
 ///         with multiple OCR plugin support.
 abstract contract MultiOCR3Base is ITypeAndVersion, OwnerIsCreator {
@@ -50,7 +49,6 @@ abstract contract MultiOCR3Base is ITypeAndVersion, OwnerIsCreator {
     bytes32 configDigest;
     uint8 F; // ──────────────────────────────╮ maximum number of faulty/dishonest oracles the system can tolerate
     uint8 n; //                               │ number of signers / transmitters
-    bool uniqueReports; //                    │ if true, the reports should be unique
     bool isSignatureVerificationEnabled; // ──╯ if true, requires signers and verifies signatures on transmission verification
   }
 
@@ -85,7 +83,6 @@ abstract contract MultiOCR3Base is ITypeAndVersion, OwnerIsCreator {
     bytes32 configDigest; // Config digest to update to
     uint8 ocrPluginType; // ──────────────────╮ OCR plugin type to update config for
     uint8 F; //                               │ maximum number of faulty/dishonest oracles
-    bool uniqueReports; //                    │ if true, the reports should be unique
     bool isSignatureVerificationEnabled; // ──╯ if true, requires signers and verifies signatures on transmission verification
     address[] signers; // signing address of each oracle
     address[] transmitters; // transmission address of each oracle (i.e. the address the oracle actually sends transactions to the contract from)
@@ -143,12 +140,8 @@ abstract contract MultiOCR3Base is ITypeAndVersion, OwnerIsCreator {
 
     // If F is 0, then the config is not yet set
     if (configInfo.F == 0) {
-      configInfo.uniqueReports = ocrConfigArgs.uniqueReports;
       configInfo.isSignatureVerificationEnabled = ocrConfigArgs.isSignatureVerificationEnabled;
-    } else if (
-      configInfo.uniqueReports != ocrConfigArgs.uniqueReports
-        || configInfo.isSignatureVerificationEnabled != ocrConfigArgs.isSignatureVerificationEnabled
-    ) {
+    } else if (configInfo.isSignatureVerificationEnabled != ocrConfigArgs.isSignatureVerificationEnabled) {
       revert StaticConfigCannotBeChanged(ocrPluginType);
     }
 
@@ -228,15 +221,13 @@ abstract contract MultiOCR3Base is ITypeAndVersion, OwnerIsCreator {
     // TRANSMIT_MSGDATA_CONSTANT_LENGTH_COMPONENT need to be changed accordingly
     bytes32[3] calldata reportContext,
     bytes calldata report,
-    // TODO: revisit trade-off - converting this to calldata and using one CONSTANT_LENGTH_COMPONENT
-    //       decreases contract size by ~220B, decreasees commit gas usage by ~400 gas, but increases exec gas usage by ~3600 gas
     bytes32[] memory rs,
     bytes32[] memory ss,
     bytes32 rawVs // signatures
   ) internal {
     // reportContext consists of:
     // reportContext[0]: ConfigDigest
-    // reportContext[1]: 27 byte padding, 4-byte epoch and 1-byte round
+    // reportContext[1]: 24 byte padding, 8 byte sequence number
     // reportContext[2]: ExtraHash
     ConfigInfo memory configInfo = s_ocrConfigs[ocrPluginType].configInfo;
     bytes32 configDigest = reportContext[0];
@@ -259,7 +250,7 @@ abstract contract MultiOCR3Base is ITypeAndVersion, OwnerIsCreator {
     // If the cached chainID at time of deployment doesn't match the current chainID, we reject all signed reports.
     // This avoids a (rare) scenario where chain A forks into chain A and A', A' still has configDigest
     // calculated from chain A and so OCR reports will be valid on both forks.
-    if (i_chainID != block.chainid) revert ForkedChain(i_chainID, block.chainid);
+    _whenChainNotForked();
 
     // Scoping this reduces stack pressure and gas usage
     {
@@ -278,21 +269,15 @@ abstract contract MultiOCR3Base is ITypeAndVersion, OwnerIsCreator {
     if (configInfo.isSignatureVerificationEnabled) {
       // Scoping to reduce stack pressure
       {
-        uint256 expectedNumSignatures;
-        if (configInfo.uniqueReports) {
-          expectedNumSignatures = (configInfo.n + configInfo.F) / 2 + 1;
-        } else {
-          expectedNumSignatures = configInfo.F + 1;
-        }
-        if (rs.length != expectedNumSignatures) revert WrongNumberOfSignatures();
+        if (rs.length != configInfo.F + 1) revert WrongNumberOfSignatures();
         if (rs.length != ss.length) revert SignaturesOutOfRegistration();
       }
 
       bytes32 h = keccak256(abi.encodePacked(keccak256(report), reportContext));
       _verifySignatures(ocrPluginType, h, rs, ss, rawVs);
     }
 
-    emit Transmitted(ocrPluginType, configDigest, uint32(uint256(reportContext[1]) >> 8));
+    emit Transmitted(ocrPluginType, configDigest, uint64(uint256(reportContext[1])));
   }
 
   /// @notice verifies the signatures of a hashed report value for one OCR plugin type
@@ -324,6 +309,11 @@ abstract contract MultiOCR3Base is ITypeAndVersion, OwnerIsCreator {
     }
   }
 
+  /// @notice Validates that the chain ID has not diverged after deployment. Reverts if the chain IDs do not match
+  function _whenChainNotForked() internal view {
+    if (i_chainID != block.chainid) revert ForkedChain(i_chainID, block.chainid);
+  }
+
   /// @notice information about current offchain reporting protocol configuration
   /// @param ocrPluginType OCR plugin type to return config details for
   /// @return ocrConfig OCR config for the plugin type