comments

Author: fcarreiro

barretenberg/cpp/src/barretenberg/vm2/simulation/lib/serialization.hpp

@@ -15,6 +15,9 @@ namespace bb::avm2::simulation {
 class Operand {
   private:
     // We use unique ptrs to bound the size of the Operand class to the size of a pointer.
+    // FIXME: Not true! Sadly the variant is sizeof(ptr) + 1 = 8 + 1, but it's aligned,
+    // so it's 16 bytes which wastes 7 bytes. Still better than 32 + 1 + padding = 40 bytes,
+    // but worth it?
     using FieldInHeap = std::unique_ptr<FF>;
     using U128InHeap = std::unique_ptr<uint128_t>;
     using Variant = std::variant<uint8_t, uint16_t, uint32_t, uint64_t, FieldInHeap, U128InHeap>;

barretenberg/cpp/src/barretenberg/vm2/tracegen/lib/lookup_builder.hpp

@@ -9,8 +9,6 @@
 
 namespace bb::avm2::tracegen {
 
-// TODO: This builds the counts. Think if it should do more or change name.
-
 template <typename LookupSettings_> class BaseLookupTraceBuilder {
   public:
     virtual ~BaseLookupTraceBuilder() = default;

barretenberg/cpp/src/barretenberg/vm2/tracegen/trace_container.hpp

@@ -57,6 +57,9 @@ class TraceContainer {
         std::shared_mutex mutex;
         uint32_t max_row_number = 0;
         bool row_number_dirty; // needs recalculation
+        // Future memory optimization notes: we can do the same trick as in Operand.
+        // That is, store a variant with a unique_ptr. However, we should benchmark this.
+        // (see serialization.hpp).
         unordered_flat_map<uint32_t, FF> rows;
     };
     static constexpr size_t NUM_COLUMNS = static_cast<size_t>(ColumnAndShifts::NUM_COLUMNS);