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Reduced complexity of logic supressing cache operations.

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This commit is contained in:
Ross Thompson 2022-11-01 15:23:24 -05:00
parent e8d7607e87
commit 44171c342d
5 changed files with 33 additions and 38 deletions
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12
pipelined/src/cache/cache.sv vendored
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@ -35,8 +35,8 @@ module cache #(parameter LINELEN, NUMLINES, NUMWAYS, LOGBWPL, WORDLEN, MUXINTE
input logic reset,
// cpu side
input logic CPUBusy,
input logic [1:0] RW,
input logic [1:0] Atomic,
input logic [1:0] CacheRW,
input logic [1:0] CacheAtomic,
input logic FlushCache,
input logic InvalidateCache,
input logic [11:0] NextAdr, // virtual address, but we only use the lower 12 bits.
@ -49,9 +49,6 @@ module cache #(parameter LINELEN, NUMLINES, NUMWAYS, LOGBWPL, WORDLEN, MUXINTE
output logic CacheMiss,
output logic CacheAccess,
// lsu control
input logic IgnoreRequestTLB,
input logic TrapM,
input logic Cacheable,
input logic SelHPTW,
// Bus fsm interface
output logic [1:0] CacheBusRW,
@ -102,7 +99,6 @@ module cache #(parameter LINELEN, NUMLINES, NUMWAYS, LOGBWPL, WORDLEN, MUXINTE
logic ResetOrFlushAdr, ResetOrFlushWay;
logic [NUMWAYS-1:0] SelectedWay;
logic [NUMWAYS-1:0] SetValidWay, ClearValidWay, SetDirtyWay, ClearDirtyWay;
logic [1:0] CacheRW, CacheAtomic;
logic [LINELEN-1:0] ReadDataLine, ReadDataLineCache;
logic [$clog2(LINELEN/8) - $clog2(MUXINTERVAL/8) - 1:0] WordOffsetAddr;
logic SelBusBuffer;
@ -209,10 +205,8 @@ module cache #(parameter LINELEN, NUMLINES, NUMWAYS, LOGBWPL, WORDLEN, MUXINTE
/////////////////////////////////////////////////////////////////////////////////////////////
// Cache FSM
/////////////////////////////////////////////////////////////////////////////////////////////
assign CacheRW = Cacheable ? RW : 2'b00;
assign CacheAtomic = Cacheable ? Atomic : 2'b00;
cachefsm cachefsm(.clk, .reset, .CacheBusRW, .CacheBusAck,
.CacheRW, .CacheAtomic, .CPUBusy, .IgnoreRequestTLB, .TrapM,
.CacheRW, .CacheAtomic, .CPUBusy,
.CacheHit, .VictimDirty, .CacheStall, .CacheCommitted,
.CacheMiss, .CacheAccess, .SelAdr,
.ClearValid, .ClearDirty, .SetDirty,

22
pipelined/src/cache/cachefsm.sv vendored
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@ -40,9 +40,6 @@ module cachefsm
input logic InvalidateCache,
// hazard inputs
input logic CPUBusy,
// interlock fsm
input logic IgnoreRequestTLB,
input logic TrapM,
// Bus inputs
input logic CacheBusAck,
// dcache internals
@ -96,17 +93,12 @@ module cachefsm
STATE_FLUSH_WRITE_BACK} statetype;
(* mark_debug = "true" *) statetype CurrState, NextState;
logic IgnoreRequest;
assign IgnoreRequest = IgnoreRequestTLB | TrapM;
// if the command is used in the READY state then the cache needs to be able to supress
// using both IgnoreRequestTLB and DCacheTrapM. Otherwise we can just use IgnoreRequestTLB.
assign DoFlush = FlushCache & ~TrapM; // do NOT suppress flush on DTLBMissM. Does not depend on address translation.
assign DoFlush = FlushCache;
assign AMO = CacheAtomic[1] & (&CacheRW);
assign DoAMO = AMO & ~IgnoreRequest;
assign DoRead = CacheRW[1] & ~IgnoreRequest;
assign DoWrite = CacheRW[0] & ~IgnoreRequest;
assign DoAMO = AMO;
assign DoRead = CacheRW[1];
assign DoWrite = CacheRW[0];
assign DoAnyMiss = (DoAMO | DoRead | DoWrite) & ~CacheHit & ~InvalidateCache;
assign DoAnyUpdateHit = (DoAMO | DoWrite) & CacheHit;
@ -129,7 +121,7 @@ module cachefsm
always_comb begin
NextState = STATE_READY;
case (CurrState)
STATE_READY: if(IgnoreRequest | InvalidateCache) NextState = STATE_READY;
STATE_READY: if(InvalidateCache) NextState = STATE_READY;
else if(DoFlush) NextState = STATE_FLUSH;
// Delayed LRU update. Cannot check if victim line is dirty on this cycle.
// To optimize do the fetch first, then eviction if necessary.
@ -204,9 +196,7 @@ module cachefsm
// assign CacheBusRW[0] = (CurrState == STATE_MISS_FETCH_WDV & CacheBusAck & VictimDirty) |
// (CurrState == STATE_FLUSH_CHECK & VictimDirty);
// **** can this be simplified?
assign SelAdr = (CurrState == STATE_READY & (IgnoreRequestTLB & ~TrapM)) | // Ignore Request is needed on TLB miss.
// use the raw requests as we don't want TrapM in the critical path
(CurrState == STATE_READY & ((AMO | CacheRW[0]) & CacheHit)) | // changes if store delay hazard removed
assign SelAdr = (CurrState == STATE_READY & ((AMO | CacheRW[0]) & CacheHit)) | // changes if store delay hazard removed
(CurrState == STATE_READY & (DoAnyMiss)) |
(CurrState == STATE_MISS_FETCH_WDV) |
(CurrState == STATE_MISS_EVICT_DIRTY) |

11
pipelined/src/ifu/ifu.sv
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@ -212,26 +212,25 @@ module ifu (
logic [LINELEN-1:0] FetchBuffer;
logic [`PA_BITS-1:0] ICacheBusAdr;
logic ICacheBusAck;
logic [1:0] CacheBusRW, BusRW;
logic [1:0] CacheBusRW, BusRW, CacheRWF;
//assign BusRW = IFURWF & ~{IgnoreRequest, IgnoreRequest} & ~{CacheableF, CacheableF} & ~{SelIROM, SelIROM};
assign BusRW = ~IgnoreRequest & ~CacheableF & ~SelIROM ? IFURWF : '0;
assign CacheRWF = ~IgnoreRequest & CacheableF & ~SelIROM ? IFURWF : '0;
cache #(.LINELEN(`ICACHE_LINELENINBITS),
.NUMLINES(`ICACHE_WAYSIZEINBYTES*8/`ICACHE_LINELENINBITS),
.NUMWAYS(`ICACHE_NUMWAYS), .LOGBWPL(LOGBWPL), .WORDLEN(32), .MUXINTERVAL(16), .DCACHE(0))
icache(.clk, .reset, .CPUBusy, .IgnoreRequestTLB(ITLBMissF), .TrapM,
icache(.clk, .reset, .CPUBusy,
.FetchBuffer, .CacheBusAck(ICacheBusAck),
.CacheBusAdr(ICacheBusAdr), .CacheStall(ICacheStallF),
.CacheBusRW,
.ReadDataWord(ICacheInstrF),
.Cacheable(CacheableF),
.SelHPTW('0),
.CacheMiss(ICacheMiss), .CacheAccess(ICacheAccess),
.ByteMask('0), .WordCount('0), .SelBusWord('0),
.FinalWriteData('0),
.RW(IFURWF),
.Atomic('0), .FlushCache('0),
.CacheRW(CacheRWF),
.CacheAtomic('0), .FlushCache('0),
.NextAdr(PCNextFSpill[11:0]),
.PAdr(PCPF),
.CacheCommitted(CacheCommittedF), .InvalidateCache(InvalidateICacheM));

21
pipelined/src/lsu/lsu.sv
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@ -212,6 +212,8 @@ module lsu (
// The DTIM uses untranslated addresses, so it is not compatible with virtual memory.
assign DTIMAdr = MemRWM[0] ? IEUAdrExtM[`PA_BITS-1:0] : IEUAdrExtE[`PA_BITS-1:0]; // zero extend or contract to PA_BITS
assign DTIMMemRWM = SelDTIM & ~IgnoreRequest ? LSURWM : '0;
// **** fix ReadDataWordM to be LLEN. ByteMask is wrong length.
// **** create config to support DTIM with floating point.
dtim dtim(.clk, .reset, .ce(~CPUBusy), .MemRWM(DTIMMemRWM),
.Adr(DTIMAdr),
.TrapM, .WriteDataM(LSUWriteDataM),
@ -237,18 +239,23 @@ module lsu (
logic [1:0] CacheBusRW, BusRW;
localparam integer LLENPOVERAHBW = `LLEN / `AHBW;
logic CacheableOrFlushCacheM;
logic [1:0] CacheRWM, CacheAtomicM;
logic CacheFlushM;
assign BusRW = ~CacheableM & ~IgnoreRequest & ~SelDTIM ? LSURWM : '0;
assign CacheableOrFlushCacheM = CacheableM | FlushDCacheM;
assign CacheRWM = CacheableM & ~IgnoreRequest & ~SelDTIM ? LSURWM : '0;
assign CacheAtomicM = CacheableM & ~IgnoreRequest & ~SelDTIM ? LSUAtomicM : '0;
assign CacheFlushM = ~TrapM & FlushDCacheM;
cache #(.LINELEN(`DCACHE_LINELENINBITS), .NUMLINES(`DCACHE_WAYSIZEINBYTES*8/LINELEN),
.NUMWAYS(`DCACHE_NUMWAYS), .LOGBWPL(LLENLOGBWPL), .WORDLEN(`LLEN), .MUXINTERVAL(`LLEN), .DCACHE(1)) dcache(
.clk, .reset, .CPUBusy, .SelBusWord, .RW(LSURWM), .Atomic(LSUAtomicM),
.FlushCache(FlushDCacheM), .NextAdr(IEUAdrE[11:0]), .PAdr(PAdrM),
.clk, .reset, .CPUBusy, .SelBusWord, .CacheRW(CacheRWM), .CacheAtomic(CacheAtomicM),
.FlushCache(CacheFlushM), .NextAdr(IEUAdrE[11:0]), .PAdr(PAdrM),
.ByteMask(ByteMaskM), .WordCount(WordCount[AHBWLOGBWPL-1:AHBWLOGBWPL-LLENLOGBWPL]),
.FinalWriteData(LSUWriteDataM), .Cacheable(CacheableOrFlushCacheM), .SelHPTW,
.FinalWriteData(LSUWriteDataM), .SelHPTW,
.CacheStall(DCacheStallM), .CacheMiss(DCacheMiss), .CacheAccess(DCacheAccess),
.IgnoreRequestTLB, .TrapM, .CacheCommitted(DCacheCommittedM),
.CacheCommitted(DCacheCommittedM),
.CacheBusAdr(DCacheBusAdr), .ReadDataWord(DCacheReadDataWordM),
.FetchBuffer, .CacheBusRW,
.CacheBusAck(DCacheBusAck), .InvalidateCache(1'b0));
@ -264,6 +271,8 @@ module lsu (
// FetchBuffer[`AHBW-1:0] needs to be duplicated LLENPOVERAHBW times.
// DTIMReadDataWordM should be increased to LLEN.
// *** DTIMReadDataWordM should be LLEN
// pma should generate expection for LLEN read to periph.
mux3 #(`LLEN) UnCachedDataMux(.d0(DCacheReadDataWordM), .d1({LLENPOVERAHBW{FetchBuffer[`XLEN-1:0]}}),
.d2({{`LLEN-`XLEN{1'b0}}, DTIMReadDataWordM[`XLEN-1:0]}),
.s({SelDTIM, ~(CacheableOrFlushCacheM)}), .y(ReadDataWordMuxM));

5
pipelined/src/lsu/lsuvirtmen.sv
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@ -74,7 +74,10 @@ module lsuvirtmem(
logic ITLBMissOrDAFaultF, ITLBMissOrDAFaultNoTrapF;
logic DTLBMissOrDAFaultM, DTLBMissOrDAFaultNoTrapM;
logic SelHPTWAdr;
/// **** move to HPTW
// **** rename to walker mux?
// move all the muxes to walkermux and instantiate these in lsu under virtmem_supported.
assign ITLBMissOrDAFaultF = ITLBMissF | (`HPTW_WRITES_SUPPORTED & InstrDAPageFaultF);
assign DTLBMissOrDAFaultM = DTLBMissM | (`HPTW_WRITES_SUPPORTED & DataDAPageFaultM);
assign ITLBMissOrDAFaultNoTrapF = ITLBMissOrDAFaultF & ~TrapM;