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Restored cache store delay hazard.

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This commit is contained in:
Rose Thompson 2023-12-29 16:10:27 -06:00
parent 0264a17f77
commit 6a787981c2
4 changed files with 4 additions and 10 deletions
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3
src/cache/cache.sv vendored
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@ -34,7 +34,6 @@ module cache import cvw::*; #(parameter cvw_t P,
input logic Stall, // Stall the cache, preventing new accesses. In-flight access finished but does not return to READY
input logic FlushStage, // Pipeline flush of second stage (prevent writes and bus operations)
// cpu side
input logic [1:0] CacheRWNext, // [1] Read, [0] Write
input logic [1:0] CacheRW, // [1] Read, [0] Write
input logic FlushCache, // Flush all dirty lines back to memory
input logic InvalidateCache, // Clear all valid bits
@ -225,7 +224,7 @@ module cache import cvw::*; #(parameter cvw_t P,
/////////////////////////////////////////////////////////////////////////////////////////////
cachefsm #(P, READ_ONLY_CACHE) cachefsm(.clk, .reset, .CacheBusRW, .CacheBusAck,
.FlushStage, .CacheRW, .CacheRWNext, .Stall,
.FlushStage, .CacheRW, .Stall,
.CacheHit, .LineDirty, .HitLineDirty, .CacheStall, .CacheCommitted,
.CacheMiss, .CacheAccess, .SelAdrData, .SelAdrTag, .SelWay,
.ClearDirty, .SetDirty, .SetValid, .ClearValid, .SelWriteback, .SelFlush,

7
src/cache/cachefsm.sv vendored
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@ -38,7 +38,6 @@ module cachefsm import cvw::*; #(parameter cvw_t P,
output logic CacheStall, // Cache stalls pipeline during multicycle operation
// inputs from IEU
input logic [1:0] CacheRW, // [1] Read, [0] Write
input logic [1:0] CacheRWNext, // [1] Read, [0] Write
input logic FlushCache, // Flush all dirty lines back to memory
input logic InvalidateCache, // Clear all valid bits
input logic [3:0] CMOpM, // 0001: cbo.inval; 0010: cbo.flush; 0100: cbo.clean; 1000: cbo.zero
@ -79,7 +78,6 @@ module cachefsm import cvw::*; #(parameter cvw_t P,
logic CMOWriteback;
logic CMOZeroNoEviction;
logic StallConditions;
logic StoreHazard;
typedef enum logic [3:0]{STATE_READY, // hit states
// miss states
@ -106,8 +104,6 @@ module cachefsm import cvw::*; #(parameter cvw_t P,
assign CacheAccess = (|CacheRW) & ((CurrState == STATE_READY & ~Stall & ~FlushStage) | (CurrState == STATE_READ_HOLD & ~Stall & ~FlushStage)); // exclusion-tag: icache CacheW
assign CacheMiss = CacheAccess & ~CacheHit;
assign StoreHazard = CacheRWNext[1] & CacheRW[0] & ~CacheRW[1];
// special case on reset. When the fsm first exists reset the
// PCNextF will no longer be pointing to the correct address.
// But PCF will be the reset vector.
@ -124,7 +120,6 @@ module cachefsm import cvw::*; #(parameter cvw_t P,
else if(FlushCache & ~READ_ONLY_CACHE) NextState = STATE_FLUSH;
else if(AnyMiss & (READ_ONLY_CACHE | ~LineDirty)) NextState = STATE_FETCH; // exclusion-tag: icache FETCHStatement
else if(AnyMiss | CMOWriteback) NextState = STATE_WRITEBACK; // exclusion-tag: icache WRITEBACKStatement
else if(StoreHazard) NextState = STATE_READ_HOLD;
else NextState = STATE_READY;
STATE_FETCH: if(CacheBusAck) NextState = STATE_WRITE_LINE;
else if(CacheBusAck) NextState = STATE_READY;
@ -150,7 +145,7 @@ module cachefsm import cvw::*; #(parameter cvw_t P,
// com back to CPU
assign CacheCommitted = (CurrState != STATE_READY) & ~(READ_ONLY_CACHE & (CurrState == STATE_READ_HOLD));
assign StallConditions = FlushCache | AnyMiss | CMOWriteback | (StoreHazard);
assign StallConditions = FlushCache | AnyMiss | CMOWriteback;
assign CacheStall = (CurrState == STATE_READY & StallConditions) | // exclusion-tag: icache StallStates
(CurrState == STATE_FETCH) |
(CurrState == STATE_WRITEBACK) |

2
src/ifu/ifu.sv
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@ -247,7 +247,7 @@ module ifu import cvw::*; #(parameter cvw_t P) (
.CacheMiss(ICacheMiss), .CacheAccess(ICacheAccess),
.ByteMask('0), .BeatCount('0), .SelBusBeat('0),
.CacheWriteData('0),
.CacheRW(CacheRWF), .CacheRWNext('0), // CacheRWNext is only used to detect hazards. Not possible with icache
.CacheRW(CacheRWF),
.FlushCache('0),
.NextSet(PCSpillNextF[11:0]),
.PAdr(PCPF),

2
src/lsu/lsu.sv
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@ -322,7 +322,7 @@ module lsu import cvw::*; #(parameter cvw_t P) (
cache #(.P(P), .PA_BITS(P.PA_BITS), .XLEN(P.XLEN), .LINELEN(P.DCACHE_LINELENINBITS), .NUMLINES(P.DCACHE_WAYSIZEINBYTES*8/LINELEN),
.NUMWAYS(P.DCACHE_NUMWAYS), .LOGBWPL(LLENLOGBWPL), .WORDLEN(CACHEWORDLEN), .MUXINTERVAL(P.LLEN), .READ_ONLY_CACHE(0)) dcache(
.clk, .reset, .Stall(GatedStallW & ~SelSpillE), .SelBusBeat, .FlushStage(FlushW | IgnoreRequestTLB), .CacheRWNext(MemRWE), // *** change to LSURWE after updating hptw and atomic
.clk, .reset, .Stall(GatedStallW & ~SelSpillE), .SelBusBeat, .FlushStage(FlushW | IgnoreRequestTLB),
.CacheRW(SelStoreDelay ? 2'b00 : CacheRWM),
.FlushCache(FlushDCache), .NextSet(IEUAdrExtE[11:0]), .PAdr(PAdrM),
.ByteMask(ByteMaskSpillM), .BeatCount(BeatCount[AHBWLOGBWPL-1:AHBWLOGBWPL-LLENLOGBWPL]),