diff --git a/wally-pipelined/config/rv32ic/wally-config.vh b/wally-pipelined/config/rv32ic/wally-config.vh index fadbe36c..f369c19b 100644 --- a/wally-pipelined/config/rv32ic/wally-config.vh +++ b/wally-pipelined/config/rv32ic/wally-config.vh @@ -94,5 +94,5 @@ `define TWO_BIT_PRELOAD "../config/rv32ic/twoBitPredictor.txt" `define BTB_PRELOAD "../config/rv32ic/BTBPredictor.txt" -`define BPTYPE "BPGSHARE" // BPGLOBAL or BPTWOBIT or BPGSHARE +`define BPTYPE "BPLOCALPAg" // BPGLOBAL or BPTWOBIT or BPGSHARE `define TESTSBP 0 diff --git a/wally-pipelined/config/rv64BP/wally-config.vh b/wally-pipelined/config/rv64BP/wally-config.vh index 030c4381..34ac3d4e 100644 --- a/wally-pipelined/config/rv64BP/wally-config.vh +++ b/wally-pipelined/config/rv64BP/wally-config.vh @@ -97,5 +97,5 @@ `define TWO_BIT_PRELOAD "../config/rv64icfd/twoBitPredictor.txt" `define BTB_PRELOAD "../config/rv64icfd/BTBPredictor.txt" -`define BPTYPE "BPGSHARE" // BPGLOBAL or BPTWOBIT or BPGSHARE +`define BPTYPE "BPGLOBAL" // BPGLOBAL or BPTWOBIT or BPGSHARE `define TESTSBP 1 diff --git a/wally-pipelined/config/rv64ic/wally-config.vh b/wally-pipelined/config/rv64ic/wally-config.vh index b27a5e1c..9cfb5a8e 100644 --- a/wally-pipelined/config/rv64ic/wally-config.vh +++ b/wally-pipelined/config/rv64ic/wally-config.vh @@ -97,5 +97,5 @@ `define TWO_BIT_PRELOAD "../config/rv64ic/twoBitPredictor.txt" `define BTB_PRELOAD "../config/rv64ic/BTBPredictor.txt" -`define BPTYPE "BPGSHARE" // BPGLOBAL or BPTWOBIT or BPGSHARE +`define BPTYPE "BPLOCALPAg" // BPGLOBAL or BPTWOBIT or BPGSHARE `define TESTSBP 0 diff --git a/wally-pipelined/config/rv64icfd/wally-config.vh b/wally-pipelined/config/rv64icfd/wally-config.vh index 853b8685..6ea013d9 100644 --- a/wally-pipelined/config/rv64icfd/wally-config.vh +++ b/wally-pipelined/config/rv64icfd/wally-config.vh @@ -97,5 +97,5 @@ `define TWO_BIT_PRELOAD "../config/rv64icfd/twoBitPredictor.txt" `define BTB_PRELOAD "../config/rv64icfd/BTBPredictor.txt" -`define BPTYPE "BPGSHARE" // BPGLOBAL or BPTWOBIT or BPGSHARE +`define BPTYPE "BPGLOBAL" // BPGLOBAL or BPTWOBIT or BPGSHARE `define TESTSBP 0 diff --git a/wally-pipelined/src/ifu/bpred.sv b/wally-pipelined/src/ifu/bpred.sv index 5de3f4ec..1e54b183 100644 --- a/wally-pipelined/src/ifu/bpred.sv +++ b/wally-pipelined/src/ifu/bpred.sv @@ -107,6 +107,19 @@ module bpred .PCSrcE(PCSrcE), .UpdatePrediction(UpdateBPPredE)); end + else if (`BPTYPE == "BPLOCALPAg") begin:Predictor + + localHistoryPredictor DirPredictor(.clk(clk), + .reset(reset), + .*, // Stalls and flushes + .LookUpPC(PCNextF), + .Prediction(BPPredF), + // update + .UpdatePC(PCE), + .UpdateEN(InstrClassE[0] & ~StallE), + .PCSrcE(PCSrcE), + .UpdatePrediction(UpdateBPPredE)); + end endgenerate diff --git a/wally-pipelined/src/ifu/globalHistoryPredictor.sv b/wally-pipelined/src/ifu/globalHistoryPredictor.sv index b9addb38..1fd0720f 100644 --- a/wally-pipelined/src/ifu/globalHistoryPredictor.sv +++ b/wally-pipelined/src/ifu/globalHistoryPredictor.sv @@ -37,16 +37,17 @@ module globalHistoryPredictor output logic [1:0] Prediction, // update input logic [`XLEN-1:0] UpdatePC, - input logic UpdateEN, PCSrcE, /// *** need to add as input from bpred.sv + input logic UpdateEN, PCSrcE, input logic [1:0] UpdatePrediction ); - logic [k-1:0] GHRF, GHRD, GHRE; + logic [k-1:0] GHRF, GHRD, GHRE, GHRENext; + assign GHRENext = {PCSrcE, GHRE[k-1:1]}; flopenr #(k) GlobalHistoryRegister(.clk(clk), .reset(reset), .en(UpdateEN), - .d({PCSrcE, GHRF[k-1:1] }), + .d(GHRENext), .q(GHRF)); @@ -54,11 +55,8 @@ module globalHistoryPredictor logic [1:0] PredictionMemory; logic DoForwarding, DoForwardingF; logic [1:0] UpdatePredictionF; - - // for gshare xor the PC with the GHR - // TODO: change in sram memory2 module - // assign UpdatePCIndex = GHRE ^ UpdatePC; - // assign LookUpPCIndex = LookUpPC ^ GHR; + + // Make Prediction by reading the correct address in the PHT and also update the new address in the PHT // GHR referes to the address that the past k branches points to in the prediction stage // GHRE refers to the address that the past k branches points to in the exectution stage @@ -66,8 +64,8 @@ module globalHistoryPredictor .reset(reset), .RA1(GHRF), .RD1(PredictionMemory), - .REN1(1'b1), - .WA1(GHRE), + .REN1(~StallF), + .WA1(GHRENext), .WD1(UpdatePrediction), .WEN1(UpdateEN), .BitWEN1(2'b11)); diff --git a/wally-pipelined/src/ifu/localHistoryPredictor.sv b/wally-pipelined/src/ifu/localHistoryPredictor.sv new file mode 100644 index 00000000..ef33bbc8 --- /dev/null +++ b/wally-pipelined/src/ifu/localHistoryPredictor.sv @@ -0,0 +1,138 @@ +/////////////////////////////////////////// +// locallHistoryPredictor.sv +// +// Written: Shreya Sanghai +// Email: ssanghai@hmc.edu +// Created: March 16, 2021 +// Modified: +// +// Purpose: Global History Branch predictor with parameterized global history register +// +// A component of the Wally configurable RISC-V project. +// +// Copyright (C) 2021 Harvey Mudd College & Oklahoma State University +// +// Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation +// files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, +// modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software +// is furnished to do so, subject to the following conditions: +// +// The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. +// +// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES +// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS +// BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT +// OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. +/////////////////////////////////////////// + +`include "wally-config.vh" + +module localHistoryPredictor + #( parameter int m = 6, // 2^m = number of local history branches + parameter int k = 10 // number of past branches stored + ) + (input logic clk, + input logic reset, + input logic StallF, StallD, StallE, FlushF, FlushD, FlushE, + input logic [`XLEN-1:0] LookUpPC, + output logic [1:0] Prediction, + // update + input logic [`XLEN-1:0] UpdatePC, + input logic UpdateEN, PCSrcE, + input logic [1:0] UpdatePrediction + + ); + + logic [2**m-1:0][k-1:0] LHRNextF; + logic [k-1:0] LHRF, LHRD, LHRE, LHRENext, ForwardLHRNext; + logic [m-1:0] LookUpPCIndex, UpdatePCIndex; + logic [1:0] PredictionMemory; + logic DoForwarding, DoForwardingF, DoForwardingPHT, DoForwardingPHTF; + logic [1:0] UpdatePredictionF; + + assign LHRENext = {PCSrcE, LHRE[k-1:1]}; + assign UpdatePCIndex = {UpdatePC[m+1] ^ UpdatePC[1], UpdatePC[m:2]}; + assign LookUpPCIndex = {LookUpPC[m+1] ^ LookUpPC[1], LookUpPC[m:2]}; + +// INCASE we do ahead pipelining +// SRAM2P1R1W #(m,k) LHR(.clk(clk)), +// .reset(reset), +// .RA1(LookUpPCIndex), // need hashing function to get correct PC address +// .RD1(LHRF), +// .REN1(~StallF), +// .WA1(UpdatePCIndex), +// .WD1(LHRENExt), +// .WEN1(UpdateEN), +// .BitWEN1(2'b11)); + +genvar index; +generate + for (index = 0; index < 2**m; index = index +1) begin + + flopenr #(k) LocalHistoryRegister(.clk(clk), + .reset(reset), + .en(UpdateEN && (index == UpdatePCIndex)), + .d(LHRENext), + .q(LHRNextF[index])); + end +endgenerate + +// need to forward when updating to the same address as reading. +// first we compare to see if the update and lookup addreses are the same +assign DoForwarding = LookUpPCIndex == UpdatePCIndex; +assign ForwardLHRNext = DoForwarding ? LHRENext :LHRNextF[LookUpPCIndex]; + + // 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 + // LHRE refers to the address that the past k branches points to in the exectution stage + SRAM2P1R1W #(k, 2) PHT(.clk(clk), + .reset(reset), + .RA1(ForwardLHRNext), + .RD1(PredictionMemory), + .REN1(~StallF), + .WA1(LHRENext), + .WD1(UpdatePrediction), + .WEN1(UpdateEN), + .BitWEN1(2'b11)); + + + +assign DoForwardingPHT = LHRENext == ForwardLHRNext; + + // register the update value and the forwarding signal into the Fetch stage + // TODO: add stall logic *** + flopr #(1) DoForwardingReg(.clk(clk), + .reset(reset), + .d(DoForwardingPHT), + .q(DoForwardingPHTF)); + + flopr #(2) UpdatePredictionReg(.clk(clk), + .reset(reset), + .d(UpdatePrediction), + .q(UpdatePredictionF)); + + assign Prediction = DoForwardingPHTF ? UpdatePredictionF : PredictionMemory; + + //pipeline for LHR + flopenrc #(k) LHRFReg(.clk(clk), + .reset(reset), + .en(~StallF), + .clear(FlushF), + .d(ForwardLHRNext), + .q(LHRF)); + + flopenrc #(k) LHRDReg(.clk(clk), + .reset(reset), + .en(~StallD), + .clear(FlushD), + .d(LHRF), + .q(LHRD)); + + flopenrc #(k) LHREReg(.clk(clk), + .reset(reset), + .en(~StallE), + .clear(FlushE), + .d(LHRD), + .q(LHRE)); + +endmodule