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@muditbhargava66 muditbhargava66 released this 10 Feb 17:28
v1.4.3
e6c03f9

v1.4.3

Fixed

  • Cache Associativity Bug (Critical)

    • findVictim() now prefers empty (invalid) blocks before consulting the replacement policy
    • Previously the cache used only 1 way per set regardless of associativity, causing hit ratio to decrease with increasing associativity
    • getTagAndSet() now uses standard tag decomposition (tag = blockNumber / numSets) instead of storing the full block number as the tag, fixing incorrect writeback addresses

  • PLRU Replacement Policy

    • Replaced floating-point std::log2() with integer bit-scan loop to prevent silent truncation (e.g. log2(8) returning 2.999 → 2)
    • Added power-of-2 assertion in constructor since the tree structure requires it
    • Added missing #include <cassert>

  • Victim Cache getAllValidAddresses()

    • Replaced std::transform + std::remove(0) with a simple validity-checked loop
    • Previously, a legitimate cache block at address 0 would be silently dropped

  • Victim Cache invalidateBlocksInRange()

    • Changed from std::remove_if + erase (which physically removes elements) to in-place invalidation
    • The old approach corrupted fifoQueue and addressToIndex indices, causing incorrect evictions or crashes on subsequent operations

Changed

  • Dead Code Removal: Removed unused lruOrder, fifoOrder, and nextFifoIndex fields from CacheSet in cache_block.h and their initialization in cache.cpp — all replacement logic uses ReplacementPolicyBase instances
  • Namespace Cleanup: Moved VictimBlock and VictimCache into namespace cachesim; removed dead CacheSimulator demo class from victim_cache.h
  • Code Simplification: Removed stale "FIXED"/"SOLUTION" comments from victim_cache.h per code-simplifier guidelines
  • Version updated to v1.4.3 in CLI, CMakeLists.txt, CITATION.cff, and documentation

Added

  • Associativity Test: New tests/unit/core/associativity_test.cpp verifying that hit ratio is monotonically non-decreasing as associativity increases
  • Cache Analysis Tool: New tools/cache_analysis.cpp to visualize hit rate vs associativity and verify fix effectiveness

Documentation

  • Updated README.md "What's New" section for v1.4.3
  • Updated docs/developer/architecture.md — corrected CacheSet description and refreshed Future Extensions
  • Updated docs/features/replacement-policies.md — added PLRU power-of-2 requirement note
  • Updated docs/features/victim-cache.md — code examples now reflect cachesim namespace

Technical Details

  • All coherence protocols (MSI, MESI, MOESI) were audited and verified correct
  • All 20 tests pass (unit, integration, performance)
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