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Fixed the local branch predictor so that it at least compiles.

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This commit is contained in:
Ross Thompson 2023-04-24 11:06:53 -05:00
parent fa59c196de
commit e81445be5d
2 changed files with 28 additions and 21 deletions
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14
src/ifu/bpred/bpred.sv
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@ -127,19 +127,15 @@ module bpred (
.PCNextF, .PCM, .BPDirPredF, .BPDirPredWrongE, .PCNextF, .PCM, .BPDirPredF, .BPDirPredWrongE,
.BranchE, .BranchM, .PCSrcE); .BranchE, .BranchM, .PCSrcE);
end else if (`BPRED_TYPE == "BPLOCALPAg") begin:Predictor end else if (`BPRED_TYPE == "BP_LOCAL") begin:Predictor
// *** Fix me
/* -----\/----- EXCLUDED -----\/-----
localHistoryPredictor DirPredictor(.clk, localHistoryPredictor DirPredictor(.clk,
.reset, .StallF, .StallE, .reset, .StallD, .StallF, .StallE, .FlushD, .FlushE,
.LookUpPC(PCNextF), .LookUpPC(PCNextF),
.Prediction(BPDirPredF), .BPDirPredF,
// update // update
.UpdatePC(PCE), .UpdatePC(PCE),
.UpdateEN(InstrClassE[0] & ~StallE), .UpdateEN(BranchE & ~StallE),
.PCSrcE, .PCSrcE);
.UpdatePrediction(InstrClassE[0]));
-----/\----- EXCLUDED -----/\----- */
end end
// Part 2 Branch target address prediction // Part 2 Branch target address prediction

35
src/ifu/bpred/localHistoryPredictor.sv
View File

@ -32,13 +32,14 @@ module localHistoryPredictor #(parameter m = 6, // 2^m = number of local hist
k = 10) ( // number of past branches stored k = 10) ( // number of past branches stored
input logic clk, input logic clk,
input logic reset, input logic reset,
input logic StallF, StallE, input logic StallD, StallF, StallE,
input logic FlushD, FlushE,
input logic [`XLEN-1:0] LookUpPC, input logic [`XLEN-1:0] LookUpPC,
output logic [1:0] Prediction, output logic [1:0] BPDirPredF,
// update // update
input logic [`XLEN-1:0] UpdatePC, input logic [`XLEN-1:0] UpdatePC,
input logic UpdateEN, PCSrcE, input logic UpdateEN, PCSrcE
input logic [1:0] UpdatePrediction
); );
logic [2**m-1:0][k-1:0] LHRNextF; logic [2**m-1:0][k-1:0] LHRNextF;
@ -47,6 +48,9 @@ module localHistoryPredictor #(parameter m = 6, // 2^m = number of local hist
logic [1:0] PredictionMemory; logic [1:0] PredictionMemory;
logic DoForwarding, DoForwardingF, DoForwardingPHT, DoForwardingPHTF; logic DoForwarding, DoForwardingF, DoForwardingPHT, DoForwardingPHTF;
logic [1:0] UpdatePredictionF; logic [1:0] UpdatePredictionF;
logic [1:0] BPDirPredD, BPDirPredE;
logic [1:0] NewBPDirPredE, NewBPDirPredM;
assign LHRFNext = {PCSrcE, LHRF[k-1:1]}; assign LHRFNext = {PCSrcE, LHRF[k-1:1]};
assign UpdatePCIndex = {UpdatePC[m+1] ^ UpdatePC[1], UpdatePC[m:2]}; assign UpdatePCIndex = {UpdatePC[m+1] ^ UpdatePC[1], UpdatePC[m:2]};
@ -77,20 +81,20 @@ module localHistoryPredictor #(parameter m = 6, // 2^m = number of local hist
// Make Prediction by reading the correct address in the PHT and also update the new address in the PHT // Make Prediction by reading the correct address in the PHT and also update the new address in the PHT
// LHR referes to the address that the past k branches points to in the prediction stage // LHR referes to the address that the past k branches points to in the prediction stage
// LHRE refers to the address that the past k branches points to in the exectution stage // LHRE refers to the address that the past k branches points to in the exectution stage
ram2p1r1wb #(k, 2) PHT(.clk(clk), ram2p1r1wbe #(2**k, 2) PHT(.clk(clk),
.reset(reset), .ce1(~StallF), .ce2(UpdateEN),
.ra1(ForwardLHRNext), .ra1(ForwardLHRNext),
.rd1(PredictionMemory), .rd1(PredictionMemory),
.ren1(~StallF),
.wa2(LHRFNext), .wa2(LHRFNext),
.wd2(UpdatePrediction), .wd2(NewBPDirPredE),
.wen2(UpdateEN), .we2(UpdateEN),
.bwe2(2'b11)); .bwe2(1'b1));
assign DoForwardingPHT = LHRFNext == ForwardLHRNext; assign DoForwardingPHT = LHRFNext == ForwardLHRNext;
// register the update value and the forwarding signal into the Fetch stage // register the update value and the forwarding signal into the Fetch stage
// TODO: add stall logic *** // TODO: add stall logic ***
flopr #(1) DoForwardingReg(.clk(clk), flopr #(1) DoForwardingReg(.clk(clk),
@ -100,10 +104,13 @@ module localHistoryPredictor #(parameter m = 6, // 2^m = number of local hist
flopr #(2) UpdatePredictionReg(.clk(clk), flopr #(2) UpdatePredictionReg(.clk(clk),
.reset(reset), .reset(reset),
.d(UpdatePrediction), .d(NewBPDirPredE),
.q(UpdatePredictionF)); .q(UpdatePredictionF));
assign Prediction = DoForwardingPHTF ? UpdatePredictionF : PredictionMemory; assign BPDirPredF = DoForwardingPHTF ? UpdatePredictionF : PredictionMemory;
flopenrc #(2) PredictionRegD(clk, reset, FlushD, ~StallD, BPDirPredF, BPDirPredD);
flopenrc #(2) PredictionRegE(clk, reset, FlushE, ~StallE, BPDirPredD, BPDirPredE);
//pipeline for LHR //pipeline for LHR
flopenrc #(k) LHRFReg(.clk(clk), flopenrc #(k) LHRFReg(.clk(clk),
@ -112,6 +119,10 @@ module localHistoryPredictor #(parameter m = 6, // 2^m = number of local hist
.clear(1'b0), .clear(1'b0),
.d(ForwardLHRNext), .d(ForwardLHRNext),
.q(LHRF)); .q(LHRF));
satCounter2 BPDirUpdateE(.BrDir(PCSrcE), .OldState(BPDirPredE), .NewState(NewBPDirPredE));
/* /*
flopenrc #(k) LHRDReg(.clk(clk), flopenrc #(k) LHRDReg(.clk(clk),
.reset(reset), .reset(reset),