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fixed bug with icache miss spill fsm branch.

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This commit is contained in:
Ross Thompson 2021-05-25 14:26:22 -05:00
parent 063e458ff0
commit fec40a1b75
2 changed files with 34 additions and 66 deletions
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78
wally-pipelined/src/ifu/globalHistoryPredictor.sv
View File

@ -32,76 +32,34 @@ module globalHistoryPredictor
)
(input logic clk,
input logic reset,
input logic StallF, StallD, StallE, FlushF, FlushD, FlushE,
input logic StallF, StallD, StallE, FlushF, FlushD, FlushE,
input logic [`XLEN-1:0] LookUpPC,
output logic [1:0] Prediction,
// update
input logic [`XLEN-1:0] UpdatePC,
input logic UpdateEN, PCSrcE,
input logic [1:0] UpdatePrediction
);
logic [k-1:0] GHRF, GHRFNext;
assign GHRFNext = {PCSrcE, GHRF[k-1:1]};
logic [k-1:0] GHRF, GHRFNext;
assign GHRFNext = {PCSrcE, GHRF[k-1:1]};
flopenr #(k) GlobalHistoryRegister(.clk(clk),
.reset(reset),
.en(UpdateEN),
.d(GHRFNext),
.q(GHRF));
logic [1:0] PredictionMemory;
logic DoForwarding, DoForwardingF;
logic [1:0] UpdatePredictionF;
flopenr #(k) GlobalHistoryRegister(.clk(clk),
.reset(reset),
.en(UpdateEN),
.d(GHRFNext),
.q(GHRF));
// Make Prediction by reading the correct address in the PHT and also update the new address in the PHT
// GHR referes to the address that the past k branches points to in the prediction stage
// GHRE refers to the address that the past k branches points to in the exectution stage
SRAM2P1R1W #(k, 2) PHT(.clk(clk),
.reset(reset),
.RA1(GHRF),
.RD1(PredictionMemory),
.REN1(~StallF),
.WA1(GHRFNext),
.WD1(UpdatePrediction),
.WEN1(UpdateEN),
.BitWEN1(2'b11));
SRAM2P1R1W #(k, 2) PHT(.clk(clk),
.reset(reset),
.RA1(GHRF),
.RD1(Prediction),
.REN1(~StallF),
.WA1(GHRF),
.WD1(UpdatePrediction),
.WEN1(UpdateEN),
.BitWEN1(2'b11));
// need to forward when updating to the same address as reading.
// first we compare to see if the update and lookup addreses are the same
assign DoForwarding = GHRF == GHRFNext;
// register the update value and the forwarding signal into the Fetch stage
// TODO: add stall logic ***
flopr #(1) DoForwardingReg(.clk(clk),
.reset(reset),
.d(DoForwarding),
.q(DoForwardingF));
flopr #(2) UpdatePredictionReg(.clk(clk),
.reset(reset),
.d(UpdatePrediction),
.q(UpdatePredictionF));
assign Prediction = DoForwardingF ? UpdatePredictionF : PredictionMemory;
//pipeline for GHR
/*flopenrc #(k) GHRDReg(.clk(clk),
.reset(reset),
.en(~StallD),
.clear(FlushD),
.d(GHRF),
.q(GHRD));
flopenrc #(k) GHREReg(.clk(clk),
.reset(reset),
.en(~StallE),
.clear(FlushE),
.d(GHRD),
.q(GHRE));
*/
endmodule

22
wally-pipelined/src/ifu/icache.sv
View File

@ -154,15 +154,16 @@ module icachecontroller #(parameter LINESIZE = 256) (
localparam STATE_MISS_SPILL_FETCH_DONE = 10; // write data into SRAM/LUT
localparam STATE_MISS_SPILL_READ1 = 11; // read block 0 from SRAM/LUT
localparam STATE_MISS_SPILL_2 = 12; // return to ready if hit or do second block update.
localparam STATE_MISS_SPILL_MISS_FETCH_WDV = 13; // miss on block 1, issue read to AHB and wait
localparam STATE_MISS_SPILL_MISS_FETCH_DONE = 14; // write data to SRAM/LUT
localparam STATE_MISS_SPILL_MERGE = 15; // read block 0 of CPU access,
localparam STATE_MISS_SPILL_2_START = 13; // return to ready if hit or do second block update.
localparam STATE_MISS_SPILL_MISS_FETCH_WDV = 14; // miss on block 1, issue read to AHB and wait
localparam STATE_MISS_SPILL_MISS_FETCH_DONE = 15; // write data to SRAM/LUT
localparam STATE_MISS_SPILL_MERGE = 16; // read block 0 of CPU access,
localparam STATE_MISS_SPILL_FINAL = 16; // this state replicates STATE_READY's replay of the
localparam STATE_MISS_SPILL_FINAL = 17; // this state replicates STATE_READY's replay of the
// spill access but does nto consider spill. It also does not do another operation.
localparam STATE_INVALIDATE = 17; // *** not sure if invalidate or evict? invalidate by cache block or address?
localparam STATE_INVALIDATE = 18; // *** not sure if invalidate or evict? invalidate by cache block or address?
localparam AHBByteLength = `XLEN / 8;
localparam AHBOFFETWIDTH = $clog2(AHBByteLength);
@ -380,11 +381,20 @@ module icachecontroller #(parameter LINESIZE = 256) (
PCMux = 2'b10;
UnalignedSelect = 1'b1;
spillSave = 1'b1; /// *** Could pipeline these to make it clearer in the fsm.
ICacheReadEn = 1'b1;
NextState = STATE_MISS_SPILL_2_START;
end
STATE_MISS_SPILL_2_START: begin
if (~hit) begin
CntReset = 1'b1;
NextState = STATE_MISS_SPILL_MISS_FETCH_WDV;
end else begin
NextState = STATE_MISS_SPILL_FINAL;
NextState = STATE_READY;
ICacheReadEn = 1'b1;
PCMux = 2'b00;
UnalignedSelect = 1'b1;
SavePC = 1'b1;
ICacheStallF = 1'b0;
end
end
STATE_MISS_SPILL_MISS_FETCH_WDV: begin