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Minor change to btb.

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This commit is contained in:
Ross Thompson 2023-02-01 00:24:54 -06:00
parent a9624b1413
commit c3e3afe398
1 changed files with 10 additions and 10 deletions
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20
pipelined/src/ifu/bpred/btb.sv
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@ -50,12 +50,12 @@ module btb #(parameter int Depth = 10 ) (
logic [Depth-1:0] PCNextFIndex, PCFIndex, PCDIndex, PCEIndex; logic [Depth-1:0] PCNextFIndex, PCFIndex, PCDIndex, PCEIndex;
logic [`XLEN-1:0] ResetPC; logic [`XLEN-1:0] ResetPC;
logic MatchF, MatchD, MatchE, MatchNextX, MatchXF; logic MatchF, MatchD, MatchE, MatchNextX, MatchXF;
logic [`XLEN+3:0] ForwardBTBPrediction, ForwardBTBPredictionF; logic [`XLEN+4:0] ForwardBTBPrediction, ForwardBTBPredictionF;
logic [`XLEN+3:0] TableBTBPredictionF; logic [`XLEN+3:0] TableBTBPredictionF;
logic [`XLEN-1:0] PredPCD; logic [`XLEN-1:0] PredPCD;
logic [3:0] PredInstrClassD; // *** copy of reg outside module logic [3:0] PredInstrClassD; // *** copy of reg outside module
logic UpdateEn; logic UpdateEn;
logic TablePredValidF; logic TablePredValidF, PredValidD;
// hashing function for indexing the PC // hashing function for indexing the PC
// We have Depth bits to index, but XLEN bits as the input. // We have Depth bits to index, but XLEN bits as the input.
@ -72,20 +72,20 @@ module btb #(parameter int Depth = 10 ) (
assign ResetPC = `RESET_VECTOR; assign ResetPC = `RESET_VECTOR;
assign PCNextFIndex = reset ? ResetPC[Depth+1:2] : {PCNextF[Depth+1] ^ PCNextF[1], PCNextF[Depth:2]}; assign PCNextFIndex = reset ? ResetPC[Depth+1:2] : {PCNextF[Depth+1] ^ PCNextF[1], PCNextF[Depth:2]};
assign MatchF = PCNextFIndex == PCFIndex & PredValidF; assign MatchF = PCNextFIndex == PCFIndex;
assign MatchD = PCNextFIndex == PCDIndex; assign MatchD = PCNextFIndex == PCDIndex;
assign MatchE = PCNextFIndex == PCEIndex; assign MatchE = PCNextFIndex == PCEIndex;
assign MatchNextX = MatchF | MatchD | MatchE; assign MatchNextX = MatchF | MatchD | MatchE;
flopenr #(1) MatchReg(clk, reset, ~StallF, MatchNextX, MatchXF); flopenr #(1) MatchReg(clk, reset, ~StallF, MatchNextX, MatchXF);
assign ForwardBTBPrediction = MatchF ? {BTBPredInstrClassF, PredPCF} : assign ForwardBTBPrediction = MatchF ? {PredValidF, BTBPredInstrClassF, PredPCF} :
MatchD ? {InstrClassD, PredPCD} : MatchD ? {PredValidD, InstrClassD, PredPCD} :
{InstrClassE, IEUAdrE} ; {1'b1, InstrClassE, IEUAdrE} ;
flopenr #(`XLEN+4) ForwardBTBPredicitonReg(clk, reset, ~StallF, ForwardBTBPrediction, ForwardBTBPredictionF); flopenr #(`XLEN+5) ForwardBTBPredicitonReg(clk, reset, ~StallF, ForwardBTBPrediction, ForwardBTBPredictionF);
assign {BTBPredInstrClassF, PredPCF} = MatchXF ? ForwardBTBPredictionF : TableBTBPredictionF; assign {PredValidF, BTBPredInstrClassF, PredPCF} = MatchXF ? ForwardBTBPredictionF : {TablePredValidF, TableBTBPredictionF};
always_ff @ (posedge clk) begin always_ff @ (posedge clk) begin
if (reset) begin if (reset) begin
@ -96,7 +96,7 @@ module btb #(parameter int Depth = 10 ) (
if(~StallF | reset) TablePredValidF = ValidBits[PCNextFIndex]; if(~StallF | reset) TablePredValidF = ValidBits[PCNextFIndex];
end end
assign PredValidF = MatchXF ? 1'b1 : TablePredValidF; //assign PredValidF = MatchXF ? 1'b1 : TablePredValidF;
assign UpdateEn = |InstrClassE | PredictionInstrClassWrongE; assign UpdateEn = |InstrClassE | PredictionInstrClassWrongE;
@ -105,6 +105,6 @@ module btb #(parameter int Depth = 10 ) (
.clk, .ce1(~StallF | reset), .ra1(PCNextFIndex), .rd1(TableBTBPredictionF), .clk, .ce1(~StallF | reset), .ra1(PCNextFIndex), .rd1(TableBTBPredictionF),
.ce2(~StallM & ~FlushM), .wa2(PCEIndex), .wd2({InstrClassE, IEUAdrE}), .we2(UpdateEn), .bwe2('1)); .ce2(~StallM & ~FlushM), .wa2(PCEIndex), .wd2({InstrClassE, IEUAdrE}), .we2(UpdateEn), .bwe2('1));
flopenrc #(`XLEN) BTBD(clk, reset, FlushD, ~StallD, PredPCF, PredPCD); flopenrc #(`XLEN+1) BTBD(clk, reset, FlushD, ~StallD, {PredValidF, PredPCF}, {PredValidD, PredPCD});
endmodule endmodule