adds code decommitter stats

src/decommit.rs

@@ -94,14 +94,25 @@ impl WorldDiff {
         world: &mut dyn World<T>,
         decommit: UnpaidDecommit,
         gas: &mut u32,
-    ) -> Option<Program<T>> {
+    ) -> Option<(Program<T>, usize)> {
         if decommit.cost > *gas {
             // Unlike all other gas costs, this one is not paid if low on gas.
             return None;
         }
         *gas -= decommit.cost;
-        self.decommitted_hashes.insert(decommit.code_key, ());
-        Some(world.decommit(decommit.code_key))
+        let is_old = self
+            .decommitted_hashes
+            .insert(decommit.code_key, ())
+            .is_some();
+        let decommit = world.decommit(decommit.code_key);
+
+        let decommit_cycles = if !is_old {
+            (decommit.code_page().len() + 1) / 2
+        } else {
+            0
+        };
+
+        Some((decommit, decommit_cycles))
     }
 }
 

src/instruction_handlers/far_call.rs

@@ -114,9 +114,10 @@ fn far_call<T: Tracer, M: TypeLevelCallingMode, const IS_STATIC: bool, const IS_
             .expect("stipend must not cause overflow");
 
         let new_frame_is_static = IS_STATIC || vm.state.current_frame.is_static;
+        vm.state.code_decommitter_cycles += program.1;
         vm.push_frame::<M>(
             u256_into_address(destination_address),
-            program,
+            program.0,
             new_frame_gas,
             stipend,
             exception_handler,

src/single_instruction_test/vm.rs

@@ -95,6 +95,7 @@ impl<'a, T: Tracer> Arbitrary<'a> for VirtualMachine<T> {
                 ecrecover_cycles: 0,
                 sha256_cycles: 0,
                 secp256v1_verify_cycles: 0,
+                code_decommitter_cycles: 0,
             },
             settings: u.arbitrary()?,
             world_diff: Default::default(),

src/state.rs

@@ -35,6 +35,8 @@ pub struct State<T> {
 
     pub secp256v1_verify_cycles: usize,
 
+    pub code_decommitter_cycles: usize,
+
     pub(crate) context_u128: u128,
 }
 
@@ -87,6 +89,7 @@ impl<T> State<T> {
             ecrecover_cycles: 0,
             sha256_cycles: 0,
             secp256v1_verify_cycles: 0,
+            code_decommitter_cycles: 0,
         }
     }