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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
localaheadbp #(`BPRED_NUM_LHR, `BPRED_SIZE) DirPredictor(.clk, .reset,
.StallF, .StallD, .StallE, .StallM, .StallW, .FlushD, .FlushE, .FlushM, .FlushW,
.PCNextF, .PCM, .BPDirPredF(BPDirPredF), .BPDirPredWrongE,
.PCNextF, .PCM, .BPDirPredD(BPDirPredF), .BPDirPredWrongE,
.BranchE, .BranchM, .PCSrcE);
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 StallF, StallD, StallE, StallM, StallW,
input logic FlushD, FlushE, FlushM, FlushW,
output logic [1:0] BPDirPredF,
output logic [1:0] BPDirPredD,
output logic BPDirPredWrongE,
// update
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 [1:0] BPDirPredD, BPDirPredE;
//logic [1:0] BPDirPredE;
logic [1:0] NewBPDirPredE, NewBPDirPredM;
//logic [1:0] BPDirPredD, BPDirPredE;
logic [1:0] BPDirPredE;
logic [1:0] BPDirPredM;
logic [1:0] NewBPDirPredE, NewBPDirPredM, NewBPDirPredW;
logic [k-1:0] LHRF, LHRD, LHRE, LHRM, LHRW, LHRNextF;
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),
.ce1(~StallF), .ce2(~StallW & ~FlushW),
.ra1(LHRF),
.rd1(BPDirPredF),
.rd1(BPDirPredD),
.wa2(IndexM),
.wd2(NewBPDirPredM),
.wd2(NewBPDirPredW),
.we2(BranchM),
.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) PredictionRegM(clk, reset, FlushM, ~StallM, BPDirPredE, BPDirPredM);
satCounter2 BPDirUpdateE(.BrDir(PCSrcE), .OldState(BPDirPredE), .NewState(NewBPDirPredE));
flopenrc #(2) NewPredictionRegM(clk, reset, FlushM, ~StallM, NewBPDirPredE, NewBPDirPredM);
satCounter2 BPDirUpdateE(.BrDir(PCSrcE), .OldState(BPDirPredM), .NewState(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,
// the ghr wraps back into itself directly without