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Almost working ahead pipelined local history predictor.

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This commit is contained in:
Ross Thompson 2023-05-04 16:17:31 -05:00
parent 8235042ba2
commit ee1e380fad
2 changed files with 14 additions and 11 deletions
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2
src/ifu/bpred/bpred.sv
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@ -135,7 +135,7 @@ module bpred (
end else if (`BPRED_TYPE == "BP_LOCAL_AHEAD") begin:Predictor end else if (`BPRED_TYPE == "BP_LOCAL_AHEAD") begin:Predictor
localaheadbp #(`BPRED_NUM_LHR, `BPRED_SIZE) DirPredictor(.clk, .reset, localaheadbp #(`BPRED_NUM_LHR, `BPRED_SIZE) DirPredictor(.clk, .reset,
.StallF, .StallD, .StallE, .StallM, .StallW, .FlushD, .FlushE, .FlushM, .FlushW, .StallF, .StallD, .StallE, .StallM, .StallW, .FlushD, .FlushE, .FlushM, .FlushW,
.PCNextF, .PCM, .BPDirPredF(BPDirPredF), .BPDirPredWrongE, .PCNextF, .PCM, .BPDirPredD(BPDirPredF), .BPDirPredWrongE,
.BranchE, .BranchM, .PCSrcE); .BranchE, .BranchM, .PCSrcE);
end end

23
src/ifu/bpred/localaheadbp.sv
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@ -35,7 +35,7 @@ module localaheadbp #(parameter m = 6, // 2^m = number of local history branches
input logic reset, input logic reset,
input logic StallF, StallD, StallE, StallM, StallW, input logic StallF, StallD, StallE, StallM, StallW,
input logic FlushD, FlushE, FlushM, FlushW, input logic FlushD, FlushE, FlushM, FlushW,
output logic [1:0] BPDirPredF, output logic [1:0] BPDirPredD,
output logic BPDirPredWrongE, output logic BPDirPredWrongE,
// update // update
input logic [`XLEN-1:0] PCNextF, PCM, input logic [`XLEN-1:0] PCNextF, PCM,
@ -43,9 +43,10 @@ module localaheadbp #(parameter m = 6, // 2^m = number of local history branches
); );
logic [k-1:0] IndexNextF, IndexM; logic [k-1:0] IndexNextF, IndexM;
logic [1:0] BPDirPredD, BPDirPredE; //logic [1:0] BPDirPredD, BPDirPredE;
//logic [1:0] BPDirPredE; logic [1:0] BPDirPredE;
logic [1:0] NewBPDirPredE, NewBPDirPredM; logic [1:0] BPDirPredM;
logic [1:0] NewBPDirPredE, NewBPDirPredM, NewBPDirPredW;
logic [k-1:0] LHRF, LHRD, LHRE, LHRM, LHRW, LHRNextF; logic [k-1:0] LHRF, LHRD, LHRE, LHRM, LHRW, LHRNextF;
logic [k-1:0] LHRNextW; logic [k-1:0] LHRNextW;
@ -63,19 +64,21 @@ module localaheadbp #(parameter m = 6, // 2^m = number of local history branches
ram2p1r1wbe #(2**k, 2) PHT(.clk(clk), ram2p1r1wbe #(2**k, 2) PHT(.clk(clk),
.ce1(~StallF), .ce2(~StallW & ~FlushW), .ce1(~StallF), .ce2(~StallW & ~FlushW),
.ra1(LHRF), .ra1(LHRF),
.rd1(BPDirPredF), .rd1(BPDirPredD),
.wa2(IndexM), .wa2(IndexM),
.wd2(NewBPDirPredM), .wd2(NewBPDirPredW),
.we2(BranchM), .we2(BranchM),
.bwe2(1'b1)); .bwe2(1'b1));
flopenrc #(2) PredictionRegD(clk, reset, FlushD, ~StallD, BPDirPredF, BPDirPredD); //flopenrc #(2) PredictionRegD(clk, reset, FlushD, ~StallD, BPDirPredF, BPDirPredD);
flopenrc #(2) PredictionRegE(clk, reset, FlushE, ~StallE, BPDirPredD, BPDirPredE); flopenrc #(2) PredictionRegE(clk, reset, FlushE, ~StallE, BPDirPredD, BPDirPredE);
flopenrc #(2) PredictionRegM(clk, reset, FlushM, ~StallM, BPDirPredE, BPDirPredM);
satCounter2 BPDirUpdateE(.BrDir(PCSrcE), .OldState(BPDirPredE), .NewState(NewBPDirPredE)); satCounter2 BPDirUpdateE(.BrDir(PCSrcE), .OldState(BPDirPredM), .NewState(NewBPDirPredM));
flopenrc #(2) NewPredictionRegM(clk, reset, FlushM, ~StallM, NewBPDirPredE, NewBPDirPredM); //flopenrc #(2) NewPredictionRegM(clk, reset, FlushM, ~StallM, NewBPDirPredE, NewBPDirPredM);
flopenrc #(2) NewPredictionRegW(clk, reset, FlushW, ~StallW, NewBPDirPredM, NewBPDirPredW);
assign BPDirPredWrongE = PCSrcE != BPDirPredE[1] & BranchE; assign BPDirPredWrongE = PCSrcE != BPDirPredM[1] & BranchE;
// This is the main difference between global and local history basic implementations. In global, // This is the main difference between global and local history basic implementations. In global,
// the ghr wraps back into itself directly without // the ghr wraps back into itself directly without