Commits on May 21, 2024

1. MSHR: fix a dual-core bug when ReleaseData nests the Probe …

   Before this commit, an error scenario was discovered during dual-core TL-test:
   one client L2 requested the T permission for a block, triggering a probe to
   another L2. At the same time, the other L2 sent a Release request for the same
   block. L3 would then process the ReleaseData first by saving it in dataStorage,
   followed by receiving a probeack without data. At this point, L3 would assume
   the upper-level cache did not have the block, leading to a AcquireBlock request
   for the data block from memory, resulting in stale data being granted to L2.
   
   This commit fixes the bug by adding conditional constraints to some of the
   state transitions in L3. Two key signals were added:
   
   * `nestC_save` indicates that an AcquireBlock is nested by a ReleaseData for the
   same address, and this ReleaseData has saved into L3.
   
   * `nestC_saveDirty` indicates that nestC_save is satisfied and the ReleaseData is
   a dirty block.

   

   sumailyyc committed May 21, 2024
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