diff --git a/pipelined/src/ifu/bpred/btb.sv b/pipelined/src/ifu/bpred/btb.sv index dc32d914..7cf9ed99 100644 --- a/pipelined/src/ifu/bpred/btb.sv +++ b/pipelined/src/ifu/bpred/btb.sv @@ -50,12 +50,12 @@ module btb #(parameter int Depth = 10 ) ( logic [Depth-1:0] PCNextFIndex, PCFIndex, PCDIndex, PCEIndex; logic [`XLEN-1:0] ResetPC; 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-1:0] PredPCD; logic [3:0] PredInstrClassD; // *** copy of reg outside module logic UpdateEn; - logic TablePredValidF; + logic TablePredValidF, PredValidD; // hashing function for indexing the PC // 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 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 MatchE = PCNextFIndex == PCEIndex; assign MatchNextX = MatchF | MatchD | MatchE; flopenr #(1) MatchReg(clk, reset, ~StallF, MatchNextX, MatchXF); - assign ForwardBTBPrediction = MatchF ? {BTBPredInstrClassF, PredPCF} : - MatchD ? {InstrClassD, PredPCD} : - {InstrClassE, IEUAdrE} ; + assign ForwardBTBPrediction = MatchF ? {PredValidF, BTBPredInstrClassF, PredPCF} : + MatchD ? {PredValidD, InstrClassD, PredPCD} : + {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 if (reset) begin @@ -96,7 +96,7 @@ module btb #(parameter int Depth = 10 ) ( if(~StallF | reset) TablePredValidF = ValidBits[PCNextFIndex]; end - assign PredValidF = MatchXF ? 1'b1 : TablePredValidF; + //assign PredValidF = MatchXF ? 1'b1 : TablePredValidF; assign UpdateEn = |InstrClassE | PredictionInstrClassWrongE; @@ -105,6 +105,6 @@ module btb #(parameter int Depth = 10 ) ( .clk, .ce1(~StallF | reset), .ra1(PCNextFIndex), .rd1(TableBTBPredictionF), .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