test(contracts): Add logs to calculate gas savings

The cost of running benchmarks was determined by running them on the contracts at regenesis/0.4.0 (98e02cfa/ PR #1148), then applied to the benchmarks here to calculate both absolute and relative amounts saed

packages/contracts/test/contracts/L1/messaging/deposit.gas.spec.ts

@@ -143,7 +143,18 @@ describe('[GAS BENCHMARK] Depositing via the standard bridge', () => {
       )
 
       const receipt = await res.wait()
-      console.log('    - Gas used:', receipt.gasUsed.toNumber())
+      const gasUsed = receipt.gasUsed.toNumber()
+      const regenesis040Cost = 196_128
+      console.log('    - Gas used:', gasUsed)
+      console.log(
+        '    - Absolute savings vs regenesis/0.4.0:',
+        regenesis040Cost - gasUsed
+      )
+      console.log(
+        '    - Relative savings vs regenesis/0.4.0:',
+        (((regenesis040Cost - gasUsed) / regenesis040Cost) * 100).toFixed(2) +
+          '%'
+      )
       // Sanity check that the message was enqueued.
       expect(await CanonicalTransactionChain.getQueueLength()).to.equal(2)
     })
@@ -163,7 +174,19 @@ describe('[GAS BENCHMARK] Depositing via the standard bridge', () => {
       )
 
       const receipt = await res.wait()
-      console.log('    - Gas used:', receipt.gasUsed.toNumber())
+      const gasUsed = receipt.gasUsed.toNumber()
+      const regenesis040Cost = 244_358
+      console.log('    - Gas used:', gasUsed)
+      console.log(
+        '    - Absolute savings vs regenesis/0.4.0:',
+        regenesis040Cost - gasUsed
+      )
+      console.log(
+        '    - Relative savings vs regenesis/0.4.0:',
+        (((regenesis040Cost - gasUsed) / regenesis040Cost) * 100).toFixed(2) +
+          '%'
+      )
+
       // Sanity check that the message was enqueued.
       expect(await CanonicalTransactionChain.getQueueLength()).to.equal(3)
     })

packages/contracts/test/contracts/L1/rollup/CanonicalTransactionChain.gas.spec.ts

@@ -41,6 +41,19 @@ const appendSequencerBatch = async (
   })
 }
 
+const printGasSavings = (gasUsed:number, regenesis040Cost:number):void => {
+  console.log('    - Gas used:', gasUsed)
+  console.log(
+    '    - Absolute savings vs regenesis/0.4.0:',
+    regenesis040Cost - gasUsed
+  )
+  console.log(
+    '    - Relative savings vs regenesis/0.4.0:',
+    (((regenesis040Cost - gasUsed) / regenesis040Cost) * 100).toFixed(2) +
+      '%'
+  )
+}
+
 describe('[GAS BENCHMARK] CanonicalTransactionChain', () => {
   let sequencer: Signer
   before(async () => {
@@ -151,7 +164,7 @@ describe('[GAS BENCHMARK] CanonicalTransactionChain', () => {
       const gasUsed = receipt.gasUsed.toNumber()
 
       console.log('Benchmark complete.')
-      console.log('Gas used:', gasUsed)
+      printGasSavings(gasUsed, 1_616_390)
 
       console.log('Fixed calldata cost:', fixedCalldataCost)
       console.log(
@@ -199,7 +212,7 @@ describe('[GAS BENCHMARK] CanonicalTransactionChain', () => {
       const gasUsed = receipt.gasUsed.toNumber()
 
       console.log('Benchmark complete.')
-      console.log('Gas used:', gasUsed)
+      printGasSavings(gasUsed, 1_787_052)
 
       console.log('Fixed calldata cost:', fixedCalldataCost)
       console.log(
@@ -257,7 +270,7 @@ describe('[GAS BENCHMARK] CanonicalTransactionChain', () => {
       const gasUsed = receipt.gasUsed.toNumber()
 
       console.log('Benchmark complete.')
-      console.log('Gas used:', gasUsed)
+      printGasSavings(gasUsed, 2_099_387)
 
       console.log('Fixed calldata cost:', fixedCalldataCost)
       console.log(