remove ClearValid from cache

The cachefsm hardwired ClearValid logic to zero.
This signal might've been added to potentially add extra functionality
later. Unless that functionality is added, however, it negatively
impacts coverage. If the goal is to maximize coverage, this signal
should be removed and only added when it becomes necessary.

src/cache/cache.sv

@@ -76,7 +76,7 @@ module cache #(parameter LINELEN,  NUMLINES,  NUMWAYS, LOGBWPL, WORDLEN, MUXINTE
   logic [1:0]                    AdrSelMuxSel;
   logic [SETLEN-1:0]             CacheSet;
   logic [LINELEN-1:0]            LineWriteData;
-  logic                          ClearValid, ClearDirty, SetDirty, SetValid;
+  logic                          ClearDirty, SetDirty, SetValid;
   logic [LINELEN-1:0]            ReadDataLineWay [NUMWAYS-1:0];
   logic [NUMWAYS-1:0]            HitWay, ValidWay;
   logic                          CacheHit;
@@ -116,7 +116,7 @@ module cache #(parameter LINELEN,  NUMLINES,  NUMWAYS, LOGBWPL, WORDLEN, MUXINTE
   // Array of cache ways, along with victim, hit, dirty, and read merging logic
   cacheway #(NUMLINES, LINELEN, TAGLEN, OFFSETLEN, SETLEN, READ_ONLY_CACHE) CacheWays[NUMWAYS-1:0](
     .clk, .reset, .CacheEn, .CacheSet, .PAdr, .LineWriteData, .LineByteMask,
-    .SetValid, .ClearValid, .SetDirty, .ClearDirty, .SelWriteback, .VictimWay,
+    .SetValid, .SetDirty, .ClearDirty, .SelWriteback, .VictimWay,
     .FlushWay, .SelFlush, .ReadDataLineWay, .HitWay, .ValidWay, .DirtyWay, .TagWay, .FlushStage, .InvalidateCache);
 
   // Select victim way for associative caches
@@ -209,7 +209,7 @@ module cache #(parameter LINELEN,  NUMLINES,  NUMWAYS, LOGBWPL, WORDLEN, MUXINTE
     .FlushStage, .CacheRW, .CacheAtomic, .Stall,
     .CacheHit, .LineDirty, .CacheStall, .CacheCommitted, 
     .CacheMiss, .CacheAccess, .SelAdr, 
-    .ClearValid, .ClearDirty, .SetDirty, .SetValid, .SelWriteback, .SelFlush,
+    .ClearDirty, .SetDirty, .SetValid, .SelWriteback, .SelFlush,
     .FlushAdrCntEn, .FlushWayCntEn, .FlushCntRst,
     .FlushAdrFlag, .FlushWayFlag, .FlushCache, .SelFetchBuffer,
     .InvalidateCache, .CacheEn, .LRUWriteEn);

src/cache/cachefsm.sv

@@ -55,7 +55,6 @@ module cachefsm #(parameter READ_ONLY_CACHE = 0) (
   input  logic       FlushAdrFlag,      // On last set of a cache flush
   input  logic       FlushWayFlag,      // On the last way for any set of a cache flush
   output logic       SelAdr,            // [0] SRAM reads from NextAdr, [1] SRAM reads from PAdr
-  output logic       ClearValid,        // Clear the valid bit in the selected way and set
   output logic       SetValid,          // Set the dirty bit in the selected way and set
   output logic       ClearDirty,        // Clear the dirty bit in the selected way and set
   output logic       SetDirty,          // Set the dirty bit in the selected way and set
@@ -146,7 +145,6 @@ module cachefsm #(parameter READ_ONLY_CACHE = 0) (
   assign SetValid = CurrState == STATE_WRITE_LINE;
   assign SetDirty = (CurrState == STATE_READY & AnyUpdateHit) |
                     (CurrState == STATE_WRITE_LINE & (StoreAMO));
-  assign ClearValid = '0;
   assign ClearDirty = (CurrState == STATE_WRITE_LINE & ~(StoreAMO)) |
                       (CurrState == STATE_FLUSH & LineDirty); // This is wrong in a multicore snoop cache protocal.  Dirty must be cleared concurrently and atomically with writeback.  For single core cannot clear after writeback on bus ack and change flushadr.  Clears the wrong set.
   assign LRUWriteEn = (CurrState == STATE_READY & AnyHit) |

src/cache/cacheway.sv

@@ -39,7 +39,6 @@ module cacheway #(parameter NUMLINES=512, LINELEN = 256, TAGLEN = 26,
   input  logic [`PA_BITS-1:0]         PAdr,           // Physical address 
   input  logic [LINELEN-1:0]          LineWriteData,  // Final data written to cache (D$ only)
   input  logic                        SetValid,       // Set the valid bit in the selected way and set
-  input  logic                        ClearValid,     // Clear the valid bit in the selected way and set
   input  logic                        SetDirty,       // Set the dirty bit in the selected way and set
   input  logic                        ClearDirty,     // Clear the dirty bit in the selected way and set
   input  logic                        SelWriteback,   // Overrides cached tag check to select a specific way and set for writeback
@@ -71,7 +70,6 @@ module cacheway #(parameter NUMLINES=512, LINELEN = 256, TAGLEN = 26,
   logic [LINELEN/8-1:0]               FinalByteMask;
   logic                               SetValidEN;
   logic                               SetValidWay;
-  logic                               ClearValidWay;
   logic                               SetDirtyWay;
   logic                               ClearDirtyWay;
   logic                               SelNonHit;
@@ -94,7 +92,6 @@ module cacheway #(parameter NUMLINES=512, LINELEN = 256, TAGLEN = 26,
   /////////////////////////////////////////////////////////////////////////////////////////////
 
   assign SetValidWay = SetValid & SelData;
-  assign ClearValidWay = ClearValid & SelData;
   assign SetDirtyWay = SetDirty & SelData;
   assign ClearDirtyWay = ClearDirty & SelData;
   
@@ -154,7 +151,7 @@ module cacheway #(parameter NUMLINES=512, LINELEN = 256, TAGLEN = 26,
     if(CacheEn) begin 
     ValidWay <= #1 ValidBits[CacheSet];
     if(InvalidateCache)                    ValidBits <= #1 '0;
-      else if (SetValidEN | (ClearValidWay & ~FlushStage)) ValidBits[CacheSet] <= #1 SetValidWay;
+      else if (SetValidEN) ValidBits[CacheSet] <= #1 SetValidWay;
     end
   end