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Possible improvement to gshare.

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This commit is contained in:
Ross Thompson 2023-01-13 18:50:01 -06:00
parent 76a9e7d963
commit 4c78bcade8
2 changed files with 10 additions and 5 deletions
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2
pipelined/src/ifu/bpred.sv
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@ -108,7 +108,7 @@ module bpred (
speculativegshare DirPredictor(.clk, .reset, .StallF, .StallD, .StallE, .StallM, .StallW, .FlushD, .FlushE, .FlushM, .FlushW, speculativegshare DirPredictor(.clk, .reset, .StallF, .StallD, .StallE, .StallM, .StallW, .FlushD, .FlushE, .FlushM, .FlushW,
.PCNextF, .PCF, .PCD, .PCE, .PCM, .DirPredictionF, .DirPredictionWrongE, .PCNextF, .PCF, .PCD, .PCE, .PCM, .DirPredictionF, .DirPredictionWrongE,
.BranchInstrF(PredInstrClassF[0]), .BranchInstrD(InstrClassD[0]), .BranchInstrE(InstrClassE[0]), .BranchInstrM(InstrClassM[0]), .BranchInstrF(PredInstrClassF[0]), .BranchInstrD(InstrClassD[0]), .BranchInstrE(InstrClassE[0]), .BranchInstrM(InstrClassM[0]),
.BranchInstrW(InstrClassW[0]), .PCSrcE); .BranchInstrW(InstrClassW[0]), .WrongPredInstrClassD, .PCSrcE);
end else if (`BPTYPE == "BPLOCALPAg") begin:Predictor end else if (`BPTYPE == "BPLOCALPAg") begin:Predictor
// *** Fix me // *** Fix me

11
pipelined/src/ifu/speculativegshare.sv
View File

@ -41,6 +41,7 @@ module speculativegshare
// update // update
input logic [`XLEN-1:0] PCNextF, PCF, PCD, PCE, PCM, input logic [`XLEN-1:0] PCNextF, PCF, PCD, PCE, PCM,
input logic BranchInstrF, BranchInstrD, BranchInstrE, BranchInstrM, BranchInstrW, input logic BranchInstrF, BranchInstrD, BranchInstrE, BranchInstrM, BranchInstrW,
input logic [3:0] WrongPredInstrClassD,
input logic PCSrcE input logic PCSrcE
); );
@ -53,7 +54,8 @@ module speculativegshare
logic [k-1:0] GHRF; logic [k-1:0] GHRF;
logic [k:0] GHRD, OldGHRE, GHRE, GHRM, GHRW; logic [k:0] GHRD, OldGHRE, GHRE, GHRM, GHRW;
logic [k-1:0] GHRNextF; logic [k-1:0] GHRNextF;
logic [k:0] GHRNextD, GHRNextE, GHRNextM, GHRNextW; logic [k:-1] GHRNextD, OldGHRD;
logic [k:0] GHRNextE, GHRNextM, GHRNextW;
logic [k-1:0] IndexNextF, IndexF; logic [k-1:0] IndexNextF, IndexF;
logic [k-1:0] IndexD, IndexE, IndexM; logic [k-1:0] IndexD, IndexE, IndexM;
@ -118,8 +120,11 @@ module speculativegshare
flopenr #(k) GHRFReg(clk, reset, (~StallF) | FlushD, GHRNextF, GHRF); flopenr #(k) GHRFReg(clk, reset, (~StallF) | FlushD, GHRNextF, GHRF);
assign GHRNextD = FlushD ? GHRNextE : {DirPredictionF[1], GHRF}; assign GHRNextD = FlushD ? {GHRNextE, GHRNextE[0]} : {DirPredictionF[1], GHRF, GHRF[0]};
flopenr #(k+1) GHRDReg(clk, reset, (~StallD) | FlushD, GHRNextD, GHRD); flopenr #(k+2) GHRDReg(clk, reset, (~StallD) | FlushD, GHRNextD, OldGHRD);
assign GHRD = WrongPredInstrClassD[0] & BranchInstrD ? {DirPredictionD[1], OldGHRD[k:1]} : // shift right
WrongPredInstrClassD[0] & ~BranchInstrD ? OldGHRD[k-2:-1] : // shift left
OldGHRD;
assign GHRNextE = FlushE ? GHRNextM : GHRD; assign GHRNextE = FlushE ? GHRNextM : GHRD;
flopenr #(k+1) GHREReg(clk, reset, (~StallE) | FlushE, GHRNextE, OldGHRE); flopenr #(k+1) GHREReg(clk, reset, (~StallE) | FlushE, GHRNextE, OldGHRE);