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cores-swerv-el2/design/ifu/el2_ifu_bp_ctl.sv

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//********************************************************************************
// SPDX-License-Identifier: Apache-2.0
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// Copyright 2020 Western Digital Corporation or its affiliates.
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//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//********************************************************************************
//********************************************************************************
// Function: Branch predictor
// Comments:
//
//
// Bank3 : Bank2 : Bank1 : Bank0
// FA C 8 4 0
//********************************************************************************
module el2_ifu_bp_ctl
import el2_pkg::*;
#(
`include "el2_param.vh"
)
(
input logic clk,
input logic rst_l,
input logic ic_hit_f, // Icache hit, enables F address capture
input logic [31:1] ifc_fetch_addr_f, // look up btb address
input logic ifc_fetch_req_f, // F1 valid
input el2_br_tlu_pkt_t dec_tlu_br0_r_pkt, // BP commit update packet, includes errors
input logic [pt.BHT_GHR_SIZE-1:0] exu_i0_br_fghr_r, // fghr to bp
input logic [pt.BTB_ADDR_HI:pt.BTB_ADDR_LO] exu_i0_br_index_r, // bp index
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input logic [$clog2(pt.BTB_SIZE)-1:0] dec_fa_error_index, // Fully associative btb error index
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input logic dec_tlu_flush_lower_wb, // used to move EX4 RS to EX1 and F
input logic dec_tlu_flush_leak_one_wb, // don't hit for leak one fetches
input logic dec_tlu_bpred_disable, // disable all branch prediction
input el2_predict_pkt_t exu_mp_pkt, // mispredict packet
input logic [pt.BHT_GHR_SIZE-1:0] exu_mp_eghr, // execute ghr (for patching fghr)
input logic [pt.BHT_GHR_SIZE-1:0] exu_mp_fghr, // Mispredict fghr
input logic [pt.BTB_ADDR_HI:pt.BTB_ADDR_LO] exu_mp_index, // Mispredict index
input logic [pt.BTB_BTAG_SIZE-1:0] exu_mp_btag, // Mispredict btag
input logic exu_flush_final, // all flushes
output logic ifu_bp_hit_taken_f, // btb hit, select target
output logic [31:1] ifu_bp_btb_target_f, // predicted target PC
output logic ifu_bp_inst_mask_f, // tell ic which valids to kill because of a taken branch, right justified
output logic [pt.BHT_GHR_SIZE-1:0] ifu_bp_fghr_f, // fetch ghr
output logic [1:0] ifu_bp_way_f, // way
output logic [1:0] ifu_bp_ret_f, // predicted ret
output logic [1:0] ifu_bp_hist1_f, // history counters for all 4 potential branches, bit 1, right justified
output logic [1:0] ifu_bp_hist0_f, // history counters for all 4 potential branches, bit 0, right justified
output logic [1:0] ifu_bp_pc4_f, // pc4 indication, right justified
output logic [1:0] ifu_bp_valid_f, // branch valid, right justified
output logic [11:0] ifu_bp_poffset_f, // predicted target
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output logic [1:0] [$clog2(pt.BTB_SIZE)-1:0] ifu_bp_fa_index_f, // predicted branch index (fully associative option)
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input logic scan_mode
);
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localparam BTB_DWIDTH = pt.BTB_TOFFSET_SIZE+pt.BTB_BTAG_SIZE+5;
localparam BTB_DWIDTH_TOP = int'(pt.BTB_TOFFSET_SIZE)+int'(pt.BTB_BTAG_SIZE)+4;
localparam BTB_FA_INDEX = $clog2(pt.BTB_SIZE)-1;
localparam FA_CMP_LOWER = $clog2(pt.ICACHE_LN_SZ);
localparam FA_TAG_END_UPPER= 5+int'(pt.BTB_TOFFSET_SIZE)+int'(FA_CMP_LOWER)-1; // must cast to int or vcs build fails
localparam FA_TAG_START_LOWER = 3+int'(pt.BTB_TOFFSET_SIZE)+int'(FA_CMP_LOWER);
localparam FA_TAG_END_LOWER = 5+int'(pt.BTB_TOFFSET_SIZE);
localparam TAG_START=BTB_DWIDTH-1;
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localparam PC4=4;
localparam BOFF=3;
localparam CALL=2;
localparam RET=1;
localparam BV=0;
localparam LRU_SIZE=pt.BTB_ARRAY_DEPTH;
localparam NUM_BHT_LOOP = (pt.BHT_ARRAY_DEPTH > 16 ) ? 16 : pt.BHT_ARRAY_DEPTH;
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localparam NUM_BHT_LOOP_INNER_HI = (pt.BHT_ARRAY_DEPTH > 16 ) ?pt.BHT_ADDR_LO+3 : pt.BHT_ADDR_HI;
localparam NUM_BHT_LOOP_OUTER_LO = (pt.BHT_ARRAY_DEPTH > 16 ) ?pt.BHT_ADDR_LO+4 : pt.BHT_ADDR_LO;
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localparam BHT_NO_ADDR_MATCH = ( pt.BHT_ARRAY_DEPTH <= 16 );
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logic exu_mp_valid_write;
logic exu_mp_ataken;
logic exu_mp_valid; // conditional branch mispredict
logic exu_mp_boffset; // branch offsett
logic exu_mp_pc4; // branch is a 4B inst
logic exu_mp_call; // branch is a call inst
logic exu_mp_ret; // branch is a ret inst
logic exu_mp_ja; // branch is a jump always
logic [1:0] exu_mp_hist; // new history
logic [11:0] exu_mp_tgt; // target offset
logic [pt.BTB_ADDR_HI:pt.BTB_ADDR_LO] exu_mp_addr; // BTB/BHT address
logic dec_tlu_br0_v_wb; // WB stage history update
logic [1:0] dec_tlu_br0_hist_wb; // new history
logic [pt.BTB_ADDR_HI:pt.BTB_ADDR_LO] dec_tlu_br0_addr_wb; // addr
logic dec_tlu_br0_error_wb; // error; invalidate bank
logic dec_tlu_br0_start_error_wb; // error; invalidate all 4 banks in fg
logic [pt.BHT_GHR_SIZE-1:0] exu_i0_br_fghr_wb;
logic use_mp_way, use_mp_way_p1;
logic [pt.RET_STACK_SIZE-1:0][31:0] rets_out, rets_in;
logic [pt.RET_STACK_SIZE-1:0] rsenable;
logic [11:0] btb_rd_tgt_f;
logic btb_rd_pc4_f, btb_rd_call_f, btb_rd_ret_f;
logic [1:1] bp_total_branch_offset_f;
logic [31:1] bp_btb_target_adder_f;
logic [31:1] bp_rs_call_target_f;
logic rs_push, rs_pop, rs_hold;
logic [pt.BTB_ADDR_HI:pt.BTB_ADDR_LO] btb_rd_addr_p1_f, btb_wr_addr, btb_rd_addr_f;
logic [pt.BTB_BTAG_SIZE-1:0] btb_wr_tag, fetch_rd_tag_f, fetch_rd_tag_p1_f;
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logic [BTB_DWIDTH-1:0] btb_wr_data;
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logic btb_wr_en_way0, btb_wr_en_way1;
logic dec_tlu_error_wb, btb_valid, dec_tlu_br0_middle_wb;
logic [pt.BTB_ADDR_HI:pt.BTB_ADDR_LO] btb_error_addr_wb;
logic branch_error_collision_f, fetch_mp_collision_f, branch_error_collision_p1_f, fetch_mp_collision_p1_f;
logic branch_error_bank_conflict_f;
logic [pt.BHT_GHR_SIZE-1:0] merged_ghr, fghr_ns, fghr;
logic [1:0] num_valids;
logic [LRU_SIZE-1:0] btb_lru_b0_f, btb_lru_b0_hold, btb_lru_b0_ns,
fetch_wrindex_dec, fetch_wrindex_p1_dec, fetch_wrlru_b0, fetch_wrlru_p1_b0,
mp_wrindex_dec, mp_wrlru_b0;
logic btb_lru_rd_f, btb_lru_rd_p1_f, lru_update_valid_f;
logic tag_match_way0_f, tag_match_way1_f;
logic [1:0] way_raw, bht_dir_f, btb_sel_f, wayhit_f, vwayhit_f, wayhit_p1_f;
logic [1:0] bht_valid_f, bht_force_taken_f;
logic leak_one_f, leak_one_f_d1;
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logic [LRU_SIZE-1:0][BTB_DWIDTH-1:0] btb_bank0_rd_data_way0_out ;
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logic [LRU_SIZE-1:0][BTB_DWIDTH-1:0] btb_bank0_rd_data_way1_out ;
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logic [BTB_DWIDTH-1:0] btb_bank0_rd_data_way0_f ;
logic [BTB_DWIDTH-1:0] btb_bank0_rd_data_way1_f ;
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logic [BTB_DWIDTH-1:0] btb_bank0_rd_data_way0_p1_f ;
logic [BTB_DWIDTH-1:0] btb_bank0_rd_data_way1_p1_f ;
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logic [BTB_DWIDTH-1:0] btb_vbank0_rd_data_f, btb_vbank1_rd_data_f;
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logic final_h;
logic btb_fg_crossing_f;
logic middle_of_bank;
logic [1:0] bht_vbank0_rd_data_f, bht_vbank1_rd_data_f;
logic branch_error_bank_conflict_p1_f;
logic tag_match_way0_p1_f, tag_match_way1_p1_f;
logic [1:0] btb_vlru_rd_f, fetch_start_f, tag_match_vway1_expanded_f, tag_match_way0_expanded_p1_f, tag_match_way1_expanded_p1_f;
logic [31:2] fetch_addr_p1_f;
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logic exu_mp_way, exu_mp_way_f, dec_tlu_br0_way_wb, dec_tlu_way_wb;
logic [BTB_DWIDTH-1:0] btb_bank0e_rd_data_f, btb_bank0e_rd_data_p1_f;
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logic [BTB_DWIDTH-1:0] btb_bank0o_rd_data_f;
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logic [1:0] tag_match_way0_expanded_f, tag_match_way1_expanded_f;
logic [1:0] bht_bank0_rd_data_f;
logic [1:0] bht_bank1_rd_data_f;
logic [1:0] bht_bank0_rd_data_p1_f;
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genvar j, i;
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assign exu_mp_valid = exu_mp_pkt.misp & ~leak_one_f; // conditional branch mispredict
assign exu_mp_boffset = exu_mp_pkt.boffset; // branch offset
assign exu_mp_pc4 = exu_mp_pkt.pc4; // branch is a 4B inst
assign exu_mp_call = exu_mp_pkt.pcall; // branch is a call inst
assign exu_mp_ret = exu_mp_pkt.pret; // branch is a ret inst
assign exu_mp_ja = exu_mp_pkt.pja; // branch is a jump always
assign exu_mp_way = exu_mp_pkt.way; // repl way
assign exu_mp_hist[1:0] = exu_mp_pkt.hist[1:0]; // new history
assign exu_mp_tgt[11:0] = exu_mp_pkt.toffset[11:0] ; // target offset
assign exu_mp_addr[pt.BTB_ADDR_HI:pt.BTB_ADDR_LO] = exu_mp_index[pt.BTB_ADDR_HI:pt.BTB_ADDR_LO] ; // BTB/BHT address
assign exu_mp_ataken = exu_mp_pkt.ataken;
assign dec_tlu_br0_v_wb = dec_tlu_br0_r_pkt.valid;
assign dec_tlu_br0_hist_wb[1:0] = dec_tlu_br0_r_pkt.hist[1:0];
assign dec_tlu_br0_addr_wb[pt.BTB_ADDR_HI:pt.BTB_ADDR_LO] = exu_i0_br_index_r[pt.BTB_ADDR_HI:pt.BTB_ADDR_LO];
assign dec_tlu_br0_error_wb = dec_tlu_br0_r_pkt.br_error;
assign dec_tlu_br0_middle_wb = dec_tlu_br0_r_pkt.middle;
assign dec_tlu_br0_way_wb = dec_tlu_br0_r_pkt.way;
assign dec_tlu_br0_start_error_wb = dec_tlu_br0_r_pkt.br_start_error;
assign exu_i0_br_fghr_wb[pt.BHT_GHR_SIZE-1:0] = exu_i0_br_fghr_r[pt.BHT_GHR_SIZE-1:0];
// ----------------------------------------------------------------------
// READ
// ----------------------------------------------------------------------
// hash the incoming fetch PC, first guess at hashing algorithm
el2_btb_addr_hash #(.pt(pt)) f1hash(.pc(ifc_fetch_addr_f[pt.BTB_INDEX3_HI:pt.BTB_INDEX1_LO]), .hash(btb_rd_addr_f[pt.BTB_ADDR_HI:pt.BTB_ADDR_LO]));
assign fetch_addr_p1_f[31:2] = ifc_fetch_addr_f[31:2] + 30'b1;
el2_btb_addr_hash #(.pt(pt)) f1hash_p1(.pc(fetch_addr_p1_f[pt.BTB_INDEX3_HI:pt.BTB_INDEX1_LO]), .hash(btb_rd_addr_p1_f[pt.BTB_ADDR_HI:pt.BTB_ADDR_LO]));
assign btb_sel_f[1] = ~bht_dir_f[0];
assign btb_sel_f[0] = bht_dir_f[0];
assign fetch_start_f[1:0] = {ifc_fetch_addr_f[1], ~ifc_fetch_addr_f[1]};
// Errors colliding with fetches must kill the btb/bht hit.
assign branch_error_collision_f = dec_tlu_error_wb & (btb_error_addr_wb[pt.BTB_ADDR_HI:pt.BTB_ADDR_LO] == btb_rd_addr_f[pt.BTB_ADDR_HI:pt.BTB_ADDR_LO]);
assign branch_error_collision_p1_f = dec_tlu_error_wb & (btb_error_addr_wb[pt.BTB_ADDR_HI:pt.BTB_ADDR_LO] == btb_rd_addr_p1_f[pt.BTB_ADDR_HI:pt.BTB_ADDR_LO]);
assign branch_error_bank_conflict_f = branch_error_collision_f & dec_tlu_error_wb;
assign branch_error_bank_conflict_p1_f = branch_error_collision_p1_f & dec_tlu_error_wb;
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// set on leak one, hold until next flush without leak one
assign leak_one_f = (dec_tlu_flush_leak_one_wb & dec_tlu_flush_lower_wb) | (leak_one_f_d1 & ~dec_tlu_flush_lower_wb);
logic exu_flush_final_d1;
if(!pt.BTB_FULLYA) begin
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assign fetch_mp_collision_f = ( (exu_mp_btag[pt.BTB_BTAG_SIZE-1:0] == fetch_rd_tag_f[pt.BTB_BTAG_SIZE-1:0]) &
exu_mp_valid & ifc_fetch_req_f &
(exu_mp_addr[pt.BTB_ADDR_HI:pt.BTB_ADDR_LO] == btb_rd_addr_f[pt.BTB_ADDR_HI:pt.BTB_ADDR_LO])
);
assign fetch_mp_collision_p1_f = ( (exu_mp_btag[pt.BTB_BTAG_SIZE-1:0] == fetch_rd_tag_p1_f[pt.BTB_BTAG_SIZE-1:0]) &
exu_mp_valid & ifc_fetch_req_f &
(exu_mp_addr[pt.BTB_ADDR_HI:pt.BTB_ADDR_LO] == btb_rd_addr_p1_f[pt.BTB_ADDR_HI:pt.BTB_ADDR_LO])
);
// 2 -way SA, figure out the way hit and mux accordingly
assign tag_match_way0_f = btb_bank0_rd_data_way0_f[BV] & (btb_bank0_rd_data_way0_f[TAG_START:17] == fetch_rd_tag_f[pt.BTB_BTAG_SIZE-1:0]) &
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~(dec_tlu_way_wb & branch_error_bank_conflict_f) & ifc_fetch_req_f & ~leak_one_f;
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assign tag_match_way1_f = btb_bank0_rd_data_way1_f[BV] & (btb_bank0_rd_data_way1_f[TAG_START:17] == fetch_rd_tag_f[pt.BTB_BTAG_SIZE-1:0]) &
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~(dec_tlu_way_wb & branch_error_bank_conflict_f) & ifc_fetch_req_f & ~leak_one_f;
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assign tag_match_way0_p1_f = btb_bank0_rd_data_way0_p1_f[BV] & (btb_bank0_rd_data_way0_p1_f[TAG_START:17] == fetch_rd_tag_p1_f[pt.BTB_BTAG_SIZE-1:0]) &
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~(dec_tlu_way_wb & branch_error_bank_conflict_p1_f) & ifc_fetch_req_f & ~leak_one_f;
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assign tag_match_way1_p1_f = btb_bank0_rd_data_way1_p1_f[BV] & (btb_bank0_rd_data_way1_p1_f[TAG_START:17] == fetch_rd_tag_p1_f[pt.BTB_BTAG_SIZE-1:0]) &
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~(dec_tlu_way_wb & branch_error_bank_conflict_p1_f) & ifc_fetch_req_f & ~leak_one_f;
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// Both ways could hit, use the offset bit to reorder
assign tag_match_way0_expanded_f[1:0] = {tag_match_way0_f & (btb_bank0_rd_data_way0_f[BOFF] ^ btb_bank0_rd_data_way0_f[PC4]),
tag_match_way0_f & ~(btb_bank0_rd_data_way0_f[BOFF] ^ btb_bank0_rd_data_way0_f[PC4])};
assign tag_match_way1_expanded_f[1:0] = {tag_match_way1_f & (btb_bank0_rd_data_way1_f[BOFF] ^ btb_bank0_rd_data_way1_f[PC4]),
tag_match_way1_f & ~(btb_bank0_rd_data_way1_f[BOFF] ^ btb_bank0_rd_data_way1_f[PC4])};
assign tag_match_way0_expanded_p1_f[1:0] = {tag_match_way0_p1_f & (btb_bank0_rd_data_way0_p1_f[BOFF] ^ btb_bank0_rd_data_way0_p1_f[PC4]),
tag_match_way0_p1_f & ~(btb_bank0_rd_data_way0_p1_f[BOFF] ^ btb_bank0_rd_data_way0_p1_f[PC4])};
assign tag_match_way1_expanded_p1_f[1:0] = {tag_match_way1_p1_f & (btb_bank0_rd_data_way1_p1_f[BOFF] ^ btb_bank0_rd_data_way1_p1_f[PC4]),
tag_match_way1_p1_f & ~(btb_bank0_rd_data_way1_p1_f[BOFF] ^ btb_bank0_rd_data_way1_p1_f[PC4])};
assign wayhit_f[1:0] = tag_match_way0_expanded_f[1:0] | tag_match_way1_expanded_f[1:0];
assign wayhit_p1_f[1:0] = tag_match_way0_expanded_p1_f[1:0] | tag_match_way1_expanded_p1_f[1:0];
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assign btb_bank0o_rd_data_f[BTB_DWIDTH-1:0] = ( ({17+pt.BTB_BTAG_SIZE{tag_match_way0_expanded_f[1]}} & btb_bank0_rd_data_way0_f[BTB_DWIDTH-1:0]) |
({17+pt.BTB_BTAG_SIZE{tag_match_way1_expanded_f[1]}} & btb_bank0_rd_data_way1_f[BTB_DWIDTH-1:0]) );
assign btb_bank0e_rd_data_f[BTB_DWIDTH-1:0] = ( ({17+pt.BTB_BTAG_SIZE{tag_match_way0_expanded_f[0]}} & btb_bank0_rd_data_way0_f[BTB_DWIDTH-1:0]) |
({17+pt.BTB_BTAG_SIZE{tag_match_way1_expanded_f[0]}} & btb_bank0_rd_data_way1_f[BTB_DWIDTH-1:0]) );
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assign btb_bank0e_rd_data_p1_f[BTB_DWIDTH-1:0] = ( ({17+pt.BTB_BTAG_SIZE{tag_match_way0_expanded_p1_f[0]}} & btb_bank0_rd_data_way0_p1_f[BTB_DWIDTH-1:0]) |
({17+pt.BTB_BTAG_SIZE{tag_match_way1_expanded_p1_f[0]}} & btb_bank0_rd_data_way1_p1_f[BTB_DWIDTH-1:0]) );
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// virtual bank order
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assign btb_vbank0_rd_data_f[BTB_DWIDTH-1:0] = ( ({17+pt.BTB_BTAG_SIZE{fetch_start_f[0]}} & btb_bank0e_rd_data_f[BTB_DWIDTH-1:0]) |
({17+pt.BTB_BTAG_SIZE{fetch_start_f[1]}} & btb_bank0o_rd_data_f[BTB_DWIDTH-1:0]) );
assign btb_vbank1_rd_data_f[BTB_DWIDTH-1:0] = ( ({17+pt.BTB_BTAG_SIZE{fetch_start_f[0]}} & btb_bank0o_rd_data_f[BTB_DWIDTH-1:0]) |
({17+pt.BTB_BTAG_SIZE{fetch_start_f[1]}} & btb_bank0e_rd_data_p1_f[BTB_DWIDTH-1:0]) );
Initial checkin.
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assign way_raw[1:0] = tag_match_vway1_expanded_f[1:0] | (~vwayhit_f[1:0] & btb_vlru_rd_f[1:0]);
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// --------------------------------------------------------------------------------
// --------------------------------------------------------------------------------
// update lru
// mp
// create a onehot lru write vector
assign mp_wrindex_dec[LRU_SIZE-1:0] = {{LRU_SIZE-1{1'b0}},1'b1} << exu_mp_addr[pt.BTB_ADDR_HI:pt.BTB_ADDR_LO];
// fetch
assign fetch_wrindex_dec[LRU_SIZE-1:0] = {{LRU_SIZE-1{1'b0}},1'b1} << btb_rd_addr_f[pt.BTB_ADDR_HI:pt.BTB_ADDR_LO];
assign fetch_wrindex_p1_dec[LRU_SIZE-1:0] = {{LRU_SIZE-1{1'b0}},1'b1} << btb_rd_addr_p1_f[pt.BTB_ADDR_HI:pt.BTB_ADDR_LO];
assign mp_wrlru_b0[LRU_SIZE-1:0] = mp_wrindex_dec[LRU_SIZE-1:0] & {LRU_SIZE{exu_mp_valid}};
Branch 1.3
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assign btb_lru_b0_hold[LRU_SIZE-1:0] = ~mp_wrlru_b0[LRU_SIZE-1:0] & ~fetch_wrlru_b0[LRU_SIZE-1:0];
// Forward the mp lru information to the fetch, avoids multiple way hits later
assign use_mp_way = fetch_mp_collision_f;
assign use_mp_way_p1 = fetch_mp_collision_p1_f;
Initial checkin.
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assign lru_update_valid_f = (vwayhit_f[0] | vwayhit_f[1]) & ifc_fetch_req_f & ~leak_one_f;
assign fetch_wrlru_b0[LRU_SIZE-1:0] = fetch_wrindex_dec[LRU_SIZE-1:0] &
{LRU_SIZE{lru_update_valid_f}};
assign fetch_wrlru_p1_b0[LRU_SIZE-1:0] = fetch_wrindex_p1_dec[LRU_SIZE-1:0] &
{LRU_SIZE{lru_update_valid_f}};
assign btb_lru_b0_ns[LRU_SIZE-1:0] = ( (btb_lru_b0_hold[LRU_SIZE-1:0] & btb_lru_b0_f[LRU_SIZE-1:0]) |
(mp_wrlru_b0[LRU_SIZE-1:0] & {LRU_SIZE{~exu_mp_way}}) |
(fetch_wrlru_b0[LRU_SIZE-1:0] & {LRU_SIZE{tag_match_way0_f}}) |
(fetch_wrlru_p1_b0[LRU_SIZE-1:0] & {LRU_SIZE{tag_match_way0_p1_f}}) );
Branch 1.3
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Initial checkin.
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assign btb_lru_rd_f = use_mp_way ? exu_mp_way_f : |(fetch_wrindex_dec[LRU_SIZE-1:0] & btb_lru_b0_f[LRU_SIZE-1:0]);
assign btb_lru_rd_p1_f = use_mp_way_p1 ? exu_mp_way_f : |(fetch_wrindex_p1_dec[LRU_SIZE-1:0] & btb_lru_b0_f[LRU_SIZE-1:0]);
// rotated
assign btb_vlru_rd_f[1:0] = ( ({2{fetch_start_f[0]}} & {btb_lru_rd_f, btb_lru_rd_f}) |
({2{fetch_start_f[1]}} & {btb_lru_rd_p1_f, btb_lru_rd_f}));
assign tag_match_vway1_expanded_f[1:0] = ( ({2{fetch_start_f[0]}} & {tag_match_way1_expanded_f[1:0]}) |
({2{fetch_start_f[1]}} & {tag_match_way1_expanded_p1_f[0], tag_match_way1_expanded_f[1]}) );
rvdffe #(LRU_SIZE) btb_lru_ff (.*, .en(ifc_fetch_req_f | exu_mp_valid),
.din(btb_lru_b0_ns[(LRU_SIZE)-1:0]),
.dout(btb_lru_b0_f[(LRU_SIZE)-1:0]));
Branch 1.3
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end // if (!pt.BTB_FULLYA)
Initial checkin.
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// Detect end of cache line and mask as needed
logic eoc_near;
logic eoc_mask;
assign eoc_near = &ifc_fetch_addr_f[pt.ICACHE_BEAT_ADDR_HI:3];
assign eoc_mask = ~eoc_near| (|(~ifc_fetch_addr_f[2:1]));
// --------------------------------------------------------------------------------
// --------------------------------------------------------------------------------
// mux out critical hit bank for pc computation
// This is only useful for the first taken branch in the fetch group
logic [16:1] btb_sel_data_f;
assign btb_rd_tgt_f[11:0] = btb_sel_data_f[16:5];
assign btb_rd_pc4_f = btb_sel_data_f[4];
assign btb_rd_call_f = btb_sel_data_f[2];
assign btb_rd_ret_f = btb_sel_data_f[1];
assign btb_sel_data_f[16:1] = ( ({16{btb_sel_f[1]}} & btb_vbank1_rd_data_f[16:1]) |
({16{btb_sel_f[0]}} & btb_vbank0_rd_data_f[16:1]) );
logic [1:0] hist0_raw, hist1_raw, pc4_raw, pret_raw;
// a valid taken target needs to kill the next fetch as we compute the target address
assign ifu_bp_hit_taken_f = |(vwayhit_f[1:0] & hist1_raw[1:0]) & ifc_fetch_req_f & ~leak_one_f_d1 & ~dec_tlu_bpred_disable;
// Don't put calls/rets/ja in the predictor, force the bht taken instead
assign bht_force_taken_f[1:0] = {(btb_vbank1_rd_data_f[CALL] | btb_vbank1_rd_data_f[RET]),
(btb_vbank0_rd_data_f[CALL] | btb_vbank0_rd_data_f[RET])};
// taken and valid, otherwise, branch errors must clear the bht
assign bht_valid_f[1:0] = vwayhit_f[1:0];
assign bht_vbank0_rd_data_f[1:0] = ( ({2{fetch_start_f[0]}} & bht_bank0_rd_data_f[1:0]) |
({2{fetch_start_f[1]}} & bht_bank1_rd_data_f[1:0]) );
assign bht_vbank1_rd_data_f[1:0] = ( ({2{fetch_start_f[0]}} & bht_bank1_rd_data_f[1:0]) |
({2{fetch_start_f[1]}} & bht_bank0_rd_data_p1_f[1:0]) );
assign bht_dir_f[1:0] = {(bht_force_taken_f[1] | bht_vbank1_rd_data_f[1]) & bht_valid_f[1],
(bht_force_taken_f[0] | bht_vbank0_rd_data_f[1]) & bht_valid_f[0]};
assign ifu_bp_inst_mask_f = (ifu_bp_hit_taken_f & btb_sel_f[1]) | ~ifu_bp_hit_taken_f;
// Branch prediction info is sent with the 2byte lane associated with the end of the branch.
// Cases
// BANK1 BANK0
// -------------------------------
// | : | : |
// -------------------------------
// <------------> : PC4 branch, offset, should be in B1 (indicated on [2])
// <------------> : PC4 branch, no offset, indicate PC4, VALID, HIST on [1]
// <------------> : PC4 branch, offset, indicate PC4, VALID, HIST on [0]
// <------> : PC2 branch, offset, indicate VALID, HIST on [1]
// <------> : PC2 branch, no offset, indicate VALID, HIST on [0]
//
assign hist1_raw[1:0] = bht_force_taken_f[1:0] | {bht_vbank1_rd_data_f[1],
bht_vbank0_rd_data_f[1]};
assign hist0_raw[1:0] = {bht_vbank1_rd_data_f[0],
bht_vbank0_rd_data_f[0]};
assign pc4_raw[1:0] = {vwayhit_f[1] & btb_vbank1_rd_data_f[PC4],
vwayhit_f[0] & btb_vbank0_rd_data_f[PC4]};
assign pret_raw[1:0] = {vwayhit_f[1] & ~btb_vbank1_rd_data_f[CALL] & btb_vbank1_rd_data_f[RET],
vwayhit_f[0] & ~btb_vbank0_rd_data_f[CALL] & btb_vbank0_rd_data_f[RET]};
// GHR
// count the valids with masking based on first taken
assign num_valids[1:0] = countones(bht_valid_f[1:0]);
// Note that the following property holds
// P: prior ghr, H: history bit of last valid branch in line (could be 1 or 0)
// Num valid branches What new GHR must be
// 2 0H
// 1 PH
// 0 PP
assign final_h = |(btb_sel_f[1:0] & bht_dir_f[1:0]);
assign merged_ghr[pt.BHT_GHR_SIZE-1:0] = (
({pt.BHT_GHR_SIZE{num_valids[1:0] == 2'h2}} & {fghr[pt.BHT_GHR_SIZE-3:0], 1'b0, final_h}) | // 0H
({pt.BHT_GHR_SIZE{num_valids[1:0] == 2'h1}} & {fghr[pt.BHT_GHR_SIZE-2:0], final_h}) | // PH
({pt.BHT_GHR_SIZE{num_valids[1:0] == 2'h0}} & {fghr[pt.BHT_GHR_SIZE-1:0]}) ); // PP
logic [pt.BHT_GHR_SIZE-1:0] exu_flush_ghr;
assign exu_flush_ghr[pt.BHT_GHR_SIZE-1:0] = exu_mp_fghr[pt.BHT_GHR_SIZE-1:0];
assign fghr_ns[pt.BHT_GHR_SIZE-1:0] = ( ({pt.BHT_GHR_SIZE{exu_flush_final_d1}} & exu_flush_ghr[pt.BHT_GHR_SIZE-1:0]) |
({pt.BHT_GHR_SIZE{~exu_flush_final_d1 & ifc_fetch_req_f & ic_hit_f & ~leak_one_f_d1}} & merged_ghr[pt.BHT_GHR_SIZE-1:0]) |
({pt.BHT_GHR_SIZE{~exu_flush_final_d1 & ~(ifc_fetch_req_f & ic_hit_f & ~leak_one_f_d1)}} & fghr[pt.BHT_GHR_SIZE-1:0]));
Branch 1.3
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rvdffie #(.WIDTH(pt.BHT_GHR_SIZE+3),.OVERRIDE(1)) fetchghr (.*,
.din ({exu_flush_final, exu_mp_way, leak_one_f, fghr_ns[pt.BHT_GHR_SIZE-1:0]}),
.dout({exu_flush_final_d1, exu_mp_way_f, leak_one_f_d1, fghr[pt.BHT_GHR_SIZE-1:0]}));
Initial checkin.
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assign ifu_bp_fghr_f[pt.BHT_GHR_SIZE-1:0] = fghr[pt.BHT_GHR_SIZE-1:0];
assign ifu_bp_way_f[1:0] = way_raw[1:0];
assign ifu_bp_hist1_f[1:0] = hist1_raw[1:0];
assign ifu_bp_hist0_f[1:0] = hist0_raw[1:0];
assign ifu_bp_pc4_f[1:0] = pc4_raw[1:0];
assign ifu_bp_valid_f[1:0] = vwayhit_f[1:0] & ~{2{dec_tlu_bpred_disable}};
assign ifu_bp_ret_f[1:0] = pret_raw[1:0];
// compute target
// Form the fetch group offset based on the btb hit location and the location of the branch within the 4 byte chunk
// .i 5
// .o 3
// .ilb bht_dir_f[1] bht_dir_f[0] fetch_start_f[1] fetch_start_f[0] btb_rd_pc4_f
// .ob bloc_f[1] bloc_f[0] use_fa_plus
// .type fr
//
//
// ## rotdir[1:0] fs pc4 off fapl
// -1 01 - 01 0
// 10 01 - 10 0
//
// -1 10 - 10 0
// 10 10 0 01 1
// 10 10 1 01 0
logic [1:0] bloc_f;
logic use_fa_plus;
assign bloc_f[1] = (bht_dir_f[0] & ~fetch_start_f[0]) | (~bht_dir_f[0]
& fetch_start_f[0]);
assign bloc_f[0] = (bht_dir_f[0] & fetch_start_f[0]) | (~bht_dir_f[0]
& ~fetch_start_f[0]);
assign use_fa_plus = (~bht_dir_f[0] & ~fetch_start_f[0] & ~btb_rd_pc4_f);
assign btb_fg_crossing_f = fetch_start_f[0] & btb_sel_f[0] & btb_rd_pc4_f;
assign bp_total_branch_offset_f = bloc_f[1] ^ btb_rd_pc4_f;
logic [31:2] adder_pc_in_f, ifc_fetch_adder_prior;
Branch 1.3
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rvdfflie #(.WIDTH(30), .LEFT(19)) faddrf_ff (.*, .en(ifc_fetch_req_f & ~ifu_bp_hit_taken_f & ic_hit_f), .din(ifc_fetch_addr_f[31:2]), .dout(ifc_fetch_adder_prior[31:2]));
Initial checkin.
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assign ifu_bp_poffset_f[11:0] = btb_rd_tgt_f[11:0];
assign adder_pc_in_f[31:2] = ( ({30{ use_fa_plus}} & fetch_addr_p1_f[31:2]) |
({30{ btb_fg_crossing_f}} & ifc_fetch_adder_prior[31:2]) |
({30{~btb_fg_crossing_f & ~use_fa_plus}} & ifc_fetch_addr_f[31:2]));
rvbradder predtgt_addr (.pc({adder_pc_in_f[31:2], bp_total_branch_offset_f}),
.offset(btb_rd_tgt_f[11:0]),
.dout(bp_btb_target_adder_f[31:1])
);
Branch 1.3
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// mux in the return stack address here for a predicted return assuming the RS is valid, quite if no prediction
assign ifu_bp_btb_target_f[31:1] = (({31{btb_rd_ret_f & ~btb_rd_call_f & rets_out[0][0] & ifu_bp_hit_taken_f}} & rets_out[0][31:1]) |
({31{~(btb_rd_ret_f & ~btb_rd_call_f & rets_out[0][0]) & ifu_bp_hit_taken_f}} & bp_btb_target_adder_f[31:1]) );
Initial checkin.
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// ----------------------------------------------------------------------
// Return Stack
// ----------------------------------------------------------------------
rvbradder rs_addr (.pc({adder_pc_in_f[31:2], bp_total_branch_offset_f}),
.offset({11'b0, ~btb_rd_pc4_f}),
.dout(bp_rs_call_target_f[31:1])
);
assign rs_push = (btb_rd_call_f & ~btb_rd_ret_f & ifu_bp_hit_taken_f);
assign rs_pop = (btb_rd_ret_f & ~btb_rd_call_f & ifu_bp_hit_taken_f);
assign rs_hold = ~rs_push & ~rs_pop;
// Fetch based (bit 0 is a valid)
assign rets_in[0][31:0] = ( ({32{rs_push}} & {bp_rs_call_target_f[31:1], 1'b1}) | // target[31:1], valid
({32{rs_pop}} & rets_out[1][31:0]) );
assign rsenable[0] = ~rs_hold;
Branch 1.3
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for (i=0; i<pt.RET_STACK_SIZE; i++) begin : retstack
Initial checkin.
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// for the last entry in the stack, we don't have a pop position
if(i==pt.RET_STACK_SIZE-1) begin
assign rets_in[i][31:0] = rets_out[i-1][31:0];
assign rsenable[i] = rs_push;
end
else if(i>0) begin
assign rets_in[i][31:0] = ( ({32{rs_push}} & rets_out[i-1][31:0]) |
({32{rs_pop}} & rets_out[i+1][31:0]) );
assign rsenable[i] = rs_push | rs_pop;
end
rvdffe #(32) rets_ff (.*, .en(rsenable[i]), .din(rets_in[i][31:0]), .dout(rets_out[i][31:0]));
end : retstack
// ----------------------------------------------------------------------
// WRITE
// ----------------------------------------------------------------------
assign dec_tlu_error_wb = dec_tlu_br0_start_error_wb | dec_tlu_br0_error_wb;
assign btb_error_addr_wb[pt.BTB_ADDR_HI:pt.BTB_ADDR_LO] = dec_tlu_br0_addr_wb[pt.BTB_ADDR_HI:pt.BTB_ADDR_LO];
assign dec_tlu_way_wb = dec_tlu_br0_way_wb;
assign btb_valid = exu_mp_valid & ~dec_tlu_error_wb;
assign btb_wr_tag[pt.BTB_BTAG_SIZE-1:0] = exu_mp_btag[pt.BTB_BTAG_SIZE-1:0];
Branch 1.3
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if(!pt.BTB_FULLYA) begin
if(pt.BTB_BTAG_FOLD) begin : btbfold
el2_btb_tag_hash_fold #(.pt(pt)) rdtagf (.hash(fetch_rd_tag_f[pt.BTB_BTAG_SIZE-1:0]),
.pc({ifc_fetch_addr_f[pt.BTB_ADDR_HI+pt.BTB_BTAG_SIZE+pt.BTB_BTAG_SIZE:pt.BTB_ADDR_HI+1]}));
el2_btb_tag_hash_fold #(.pt(pt)) rdtagp1f(.hash(fetch_rd_tag_p1_f[pt.BTB_BTAG_SIZE-1:0]),
.pc({fetch_addr_p1_f[ pt.BTB_ADDR_HI+pt.BTB_BTAG_SIZE+pt.BTB_BTAG_SIZE:pt.BTB_ADDR_HI+1]}));
end
else begin
el2_btb_tag_hash #(.pt(pt)) rdtagf(.hash(fetch_rd_tag_f[pt.BTB_BTAG_SIZE-1:0]),
.pc({ifc_fetch_addr_f[pt.BTB_ADDR_HI+pt.BTB_BTAG_SIZE+pt.BTB_BTAG_SIZE+pt.BTB_BTAG_SIZE:pt.BTB_ADDR_HI+1]}));
el2_btb_tag_hash #(.pt(pt)) rdtagp1f(.hash(fetch_rd_tag_p1_f[pt.BTB_BTAG_SIZE-1:0]),
.pc({fetch_addr_p1_f[pt.BTB_ADDR_HI+pt.BTB_BTAG_SIZE+pt.BTB_BTAG_SIZE+pt.BTB_BTAG_SIZE:pt.BTB_ADDR_HI+1]}));
end
assign btb_wr_en_way0 = ( ({{~exu_mp_way & exu_mp_valid_write & ~dec_tlu_error_wb}}) |
({{~dec_tlu_way_wb & dec_tlu_error_wb}}));
assign btb_wr_en_way1 = ( ({{exu_mp_way & exu_mp_valid_write & ~dec_tlu_error_wb}}) |
({{dec_tlu_way_wb & dec_tlu_error_wb}}));
assign btb_wr_addr[pt.BTB_ADDR_HI:pt.BTB_ADDR_LO] = dec_tlu_error_wb ? btb_error_addr_wb[pt.BTB_ADDR_HI:pt.BTB_ADDR_LO] : exu_mp_addr[pt.BTB_ADDR_HI:pt.BTB_ADDR_LO];
Initial checkin.
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Branch 1.3
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assign vwayhit_f[1:0] = ( ({2{fetch_start_f[0]}} & {wayhit_f[1:0]}) |
({2{fetch_start_f[1]}} & {wayhit_p1_f[0], wayhit_f[1]})) & {eoc_mask, 1'b1};
Initial checkin.
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Branch 1.3
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end // if (!pt.BTB_FULLYA)
Initial checkin.
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Branch 1.3
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assign btb_wr_data[BTB_DWIDTH-1:0] = {btb_wr_tag[pt.BTB_BTAG_SIZE-1:0], exu_mp_tgt[pt.BTB_TOFFSET_SIZE-1:0], exu_mp_pc4, exu_mp_boffset,
exu_mp_call | exu_mp_ja, exu_mp_ret | exu_mp_ja, btb_valid} ;
assign exu_mp_valid_write = exu_mp_valid & exu_mp_ataken & ~exu_mp_pkt.valid;
Initial checkin.
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logic [1:0] bht_wr_data0, bht_wr_data2;
logic [1:0] bht_wr_en0, bht_wr_en2;
assign middle_of_bank = exu_mp_pc4 ^ exu_mp_boffset;
assign bht_wr_en0[1:0] = {2{exu_mp_valid & ~exu_mp_call & ~exu_mp_ret & ~exu_mp_ja}} & {middle_of_bank, ~middle_of_bank};
assign bht_wr_en2[1:0] = {2{dec_tlu_br0_v_wb}} & {dec_tlu_br0_middle_wb, ~dec_tlu_br0_middle_wb} ;
// Experiments show this is the best priority scheme for same bank/index writes at the same time.
assign bht_wr_data0[1:0] = exu_mp_hist[1:0]; // lowest priority
assign bht_wr_data2[1:0] = dec_tlu_br0_hist_wb[1:0]; // highest priority
logic [pt.BHT_ADDR_HI:pt.BHT_ADDR_LO] bht_rd_addr_f, bht_rd_addr_p1_f, bht_wr_addr0, bht_wr_addr2;
logic [pt.BHT_ADDR_HI:pt.BHT_ADDR_LO] mp_hashed, br0_hashed_wb, bht_rd_addr_hashed_f, bht_rd_addr_hashed_p1_f;
el2_btb_ghr_hash #(.pt(pt)) mpghrhs (.hashin(exu_mp_addr[pt.BTB_ADDR_HI:pt.BTB_ADDR_LO]), .ghr(exu_mp_eghr[pt.BHT_GHR_SIZE-1:0]), .hash(mp_hashed[pt.BHT_ADDR_HI:pt.BHT_ADDR_LO]));
el2_btb_ghr_hash #(.pt(pt)) br0ghrhs (.hashin(dec_tlu_br0_addr_wb[pt.BTB_ADDR_HI:pt.BTB_ADDR_LO]), .ghr(exu_i0_br_fghr_wb[pt.BHT_GHR_SIZE-1:0]), .hash(br0_hashed_wb[pt.BHT_ADDR_HI:pt.BHT_ADDR_LO]));
el2_btb_ghr_hash #(.pt(pt)) fghrhs (.hashin(btb_rd_addr_f[pt.BTB_ADDR_HI:pt.BTB_ADDR_LO]), .ghr(fghr[pt.BHT_GHR_SIZE-1:0]), .hash(bht_rd_addr_hashed_f[pt.BHT_ADDR_HI:pt.BHT_ADDR_LO]));
el2_btb_ghr_hash #(.pt(pt)) fghrhs_p1 (.hashin(btb_rd_addr_p1_f[pt.BTB_ADDR_HI:pt.BTB_ADDR_LO]), .ghr(fghr[pt.BHT_GHR_SIZE-1:0]), .hash(bht_rd_addr_hashed_p1_f[pt.BHT_ADDR_HI:pt.BHT_ADDR_LO]));
assign bht_wr_addr0[pt.BHT_ADDR_HI:pt.BHT_ADDR_LO] = mp_hashed[pt.BHT_ADDR_HI:pt.BHT_ADDR_LO];
assign bht_wr_addr2[pt.BHT_ADDR_HI:pt.BHT_ADDR_LO] = br0_hashed_wb[pt.BHT_ADDR_HI:pt.BHT_ADDR_LO];
assign bht_rd_addr_f[pt.BHT_ADDR_HI:pt.BHT_ADDR_LO] = bht_rd_addr_hashed_f[pt.BHT_ADDR_HI:pt.BHT_ADDR_LO];
assign bht_rd_addr_p1_f[pt.BHT_ADDR_HI:pt.BHT_ADDR_LO] = bht_rd_addr_hashed_p1_f[pt.BHT_ADDR_HI:pt.BHT_ADDR_LO];
// ----------------------------------------------------------------------
// Structures. Using FLOPS
// ----------------------------------------------------------------------
// BTB
// Entry -> tag[pt.BTB_BTAG_SIZE-1:0], toffset[11:0], pc4, boffset, call, ret, valid
Branch 1.3
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if(!pt.BTB_FULLYA) begin
Initial checkin.
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Branch 1.3
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for (j=0 ; j<LRU_SIZE ; j++) begin : BTB_FLOPS
// Way 0
rvdffe #(17+pt.BTB_BTAG_SIZE) btb_bank0_way0 (.*,
Initial checkin.
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.en(((btb_wr_addr[pt.BTB_ADDR_HI:pt.BTB_ADDR_LO] == j) & btb_wr_en_way0)),
Branch 1.3
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.din (btb_wr_data[BTB_DWIDTH-1:0]),
Initial checkin.
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.dout (btb_bank0_rd_data_way0_out[j]));
Branch 1.3
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// Way 1
rvdffe #(17+pt.BTB_BTAG_SIZE) btb_bank0_way1 (.*,
Initial checkin.
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.en(((btb_wr_addr[pt.BTB_ADDR_HI:pt.BTB_ADDR_LO] == j) & btb_wr_en_way1)),
Branch 1.3
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.din (btb_wr_data[BTB_DWIDTH-1:0]),
Initial checkin.
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.dout (btb_bank0_rd_data_way1_out[j]));
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end
Initial checkin.
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always_comb begin : BTB_rd_mux
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btb_bank0_rd_data_way0_f[BTB_DWIDTH-1:0] = '0 ;
btb_bank0_rd_data_way1_f[BTB_DWIDTH-1:0] = '0 ;
btb_bank0_rd_data_way0_p1_f[BTB_DWIDTH-1:0] = '0 ;
btb_bank0_rd_data_way1_p1_f[BTB_DWIDTH-1:0] = '0 ;
Initial checkin.
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for (int j=0; j< LRU_SIZE; j++) begin
if (btb_rd_addr_f[pt.BTB_ADDR_HI:pt.BTB_ADDR_LO] == (pt.BTB_ADDR_HI-pt.BTB_ADDR_LO+1)'(j)) begin
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btb_bank0_rd_data_way0_f[BTB_DWIDTH-1:0] = btb_bank0_rd_data_way0_out[j];
btb_bank0_rd_data_way1_f[BTB_DWIDTH-1:0] = btb_bank0_rd_data_way1_out[j];
Initial checkin.
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end
end
for (int j=0; j< LRU_SIZE; j++) begin
if (btb_rd_addr_p1_f[pt.BTB_ADDR_HI:pt.BTB_ADDR_LO] == (pt.BTB_ADDR_HI-pt.BTB_ADDR_LO+1)'(j)) begin
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btb_bank0_rd_data_way0_p1_f[BTB_DWIDTH-1:0] = btb_bank0_rd_data_way0_out[j];
btb_bank0_rd_data_way1_p1_f[BTB_DWIDTH-1:0] = btb_bank0_rd_data_way1_out[j];
Initial checkin.
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end
end
end
Branch 1.3
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end // if (!pt.BTB_FULLYA)
if(pt.BTB_FULLYA) begin : fa
logic found1, hit0, hit1;
logic btb_used_reset, write_used;
logic [$clog2(pt.BTB_SIZE)-1:0] btb_fa_wr_addr0, hit0_index, hit1_index;
logic [pt.BTB_SIZE-1:0] btb_tag_hit, btb_offset_0, btb_offset_1, btb_used_ns, btb_used,
wr0_en, btb_upper_hit;
logic [pt.BTB_SIZE-1:0][BTB_DWIDTH-1:0] btbdata;
// Fully Associative tag hash uses bits 31:3. Bits 2:1 are the offset bits used for the 4 tag comp banks
// Full tag used to speed up lookup. There is one 31:3 cmp per entry, and 4 2:1 cmps per entry.
logic [FA_CMP_LOWER-1:1] ifc_fetch_addr_p1_f;
assign ifc_fetch_addr_p1_f[FA_CMP_LOWER-1:1] = ifc_fetch_addr_f[FA_CMP_LOWER-1:1] + 1'b1;
assign fetch_mp_collision_f = ( (exu_mp_btag[pt.BTB_BTAG_SIZE-1:0] == ifc_fetch_addr_f[31:1]) &
exu_mp_valid & ifc_fetch_req_f & ~exu_mp_pkt.way);
assign fetch_mp_collision_p1_f = ( (exu_mp_btag[pt.BTB_BTAG_SIZE-1:0] == {ifc_fetch_addr_f[31:FA_CMP_LOWER], ifc_fetch_addr_p1_f[FA_CMP_LOWER-1:1]}) &
exu_mp_valid & ifc_fetch_req_f & ~exu_mp_pkt.way);
always_comb begin
btb_vbank0_rd_data_f = '0;
btb_vbank1_rd_data_f = '0;
btb_tag_hit = '0;
btb_upper_hit = '0;
btb_offset_0 = '0;
btb_offset_1 = '0;
found1 = 1'b0;
hit0 = 1'b0;
hit1 = 1'b0;
hit0_index = '0;
hit1_index = '0;
btb_fa_wr_addr0 = '0;
for(int i=0; i<pt.BTB_SIZE; i++) begin
// Break the cmp into chunks for lower area.
// Chunk1: FA 31:6 or 31:5 depending on icache line size
// Chunk2: FA 5:1 or 4:1 depending on icache line size
btb_upper_hit[i] = (btbdata[i][BTB_DWIDTH_TOP:FA_TAG_END_UPPER] == ifc_fetch_addr_f[31:FA_CMP_LOWER]) & btbdata[i][0] & ~wr0_en[i];
btb_offset_0[i] = (btbdata[i][FA_TAG_START_LOWER:FA_TAG_END_LOWER] == ifc_fetch_addr_f[FA_CMP_LOWER-1:1]) & btb_upper_hit[i];
btb_offset_1[i] = (btbdata[i][FA_TAG_START_LOWER:FA_TAG_END_LOWER] == ifc_fetch_addr_p1_f[FA_CMP_LOWER-1:1]) & btb_upper_hit[i];
if(~hit0) begin
if(btb_offset_0[i]) begin
hit0_index[BTB_FA_INDEX:0] = (BTB_FA_INDEX+1)'(i);
// hit unless we are also writing this entry at the same time
hit0 = 1'b1;
end
end
if(~hit1) begin
if(btb_offset_1[i]) begin
hit1_index[BTB_FA_INDEX:0] = (BTB_FA_INDEX+1)'(i);
hit1 = 1'b1;
end
end
// Mux out the 2 potential branches
if(btb_offset_0[i] == 1'b1)
btb_vbank0_rd_data_f[BTB_DWIDTH-1:0] = fetch_mp_collision_f ? btb_wr_data : btbdata[i];
if(btb_offset_1[i] == 1'b1)
btb_vbank1_rd_data_f[BTB_DWIDTH-1:0] = fetch_mp_collision_p1_f ? btb_wr_data : btbdata[i];
// find the first zero from bit zero in the used vector, this is the write address
if(~found1) begin
if(~btb_used[i]) begin
btb_fa_wr_addr0[BTB_FA_INDEX:0] = i[BTB_FA_INDEX:0];
found1 = 1'b1;
end
end
end
end // always_comb begin
`ifdef RV_ASSERT_ON
btbhitonehot0: assert #0 ($onehot0(btb_offset_0));
btbhitonehot1: assert #0 ($onehot0(btb_offset_1));
`endif
assign vwayhit_f[1:0] = {hit1, hit0} & {eoc_mask, 1'b1};
// way bit is reused as the predicted bit
assign way_raw[1:0] = vwayhit_f[1:0] | {fetch_mp_collision_p1_f, fetch_mp_collision_f};
for (j=0 ; j<pt.BTB_SIZE ; j++) begin : BTB_FAFLOPS
assign wr0_en[j] = ((btb_fa_wr_addr0[BTB_FA_INDEX:0] == j) & (exu_mp_valid_write & ~exu_mp_pkt.way)) |
((dec_fa_error_index == j) & dec_tlu_error_wb);
rvdffe #(BTB_DWIDTH) btb_fa (.*, .clk(clk),
.en (wr0_en[j]),
.din (btb_wr_data[BTB_DWIDTH-1:0]),
.dout(btbdata[j]));
end // block: BTB_FAFLOPS
assign ifu_bp_fa_index_f[1] = hit1 ? hit1_index : '0;
assign ifu_bp_fa_index_f[0] = hit0 ? hit0_index : '0;
assign btb_used_reset = &btb_used[pt.BTB_SIZE-1:0];
assign btb_used_ns[pt.BTB_SIZE-1:0] = ({pt.BTB_SIZE{vwayhit_f[1]}} & (32'b1 << hit1_index[BTB_FA_INDEX:0])) |
({pt.BTB_SIZE{vwayhit_f[0]}} & (32'b1 << hit0_index[BTB_FA_INDEX:0])) |
({pt.BTB_SIZE{exu_mp_valid_write & ~exu_mp_pkt.way & ~dec_tlu_error_wb}} & (32'b1 << btb_fa_wr_addr0[BTB_FA_INDEX:0])) |
({pt.BTB_SIZE{btb_used_reset}} & {pt.BTB_SIZE{1'b0}}) |
({pt.BTB_SIZE{~btb_used_reset & dec_tlu_error_wb}} & (btb_used[pt.BTB_SIZE-1:0] & ~(32'b1 << dec_fa_error_index[BTB_FA_INDEX:0]))) |
(~{pt.BTB_SIZE{btb_used_reset | dec_tlu_error_wb}} & btb_used[pt.BTB_SIZE-1:0]);
assign write_used = btb_used_reset | ifu_bp_hit_taken_f | exu_mp_valid_write | dec_tlu_error_wb;
rvdffe #(pt.BTB_SIZE) btb_usedf (.*, .clk(clk),
.en (write_used),
.din (btb_used_ns[pt.BTB_SIZE-1:0]),
.dout(btb_used[pt.BTB_SIZE-1:0]));
end // block: fa
Initial checkin.
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//-----------------------------------------------------------------------------
// BHT
// 2 bit Entry -> direction, strength
//
//-----------------------------------------------------------------------------
logic [1:0] [(pt.BHT_ARRAY_DEPTH/NUM_BHT_LOOP)-1:0][NUM_BHT_LOOP-1:0][1:0] bht_bank_wr_data ;
logic [1:0] [pt.BHT_ARRAY_DEPTH-1:0] [1:0] bht_bank_rd_data_out ;
logic [1:0] [(pt.BHT_ARRAY_DEPTH/NUM_BHT_LOOP)-1:0] bht_bank_clken ;
logic [1:0] [(pt.BHT_ARRAY_DEPTH/NUM_BHT_LOOP)-1:0] bht_bank_clk ;
logic [1:0] [(pt.BHT_ARRAY_DEPTH/NUM_BHT_LOOP)-1:0][NUM_BHT_LOOP-1:0] bht_bank_sel ;
for ( i=0; i<2; i++) begin : BANKS
Branch 1.3
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for (genvar k=0 ; k < (pt.BHT_ARRAY_DEPTH)/NUM_BHT_LOOP ; k++) begin : BHT_CLK_GROUP
Initial checkin.
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assign bht_bank_clken[i][k] = (bht_wr_en0[i] & ((bht_wr_addr0[pt.BHT_ADDR_HI: NUM_BHT_LOOP_OUTER_LO]==k) | BHT_NO_ADDR_MATCH)) |
(bht_wr_en2[i] & ((bht_wr_addr2[pt.BHT_ADDR_HI: NUM_BHT_LOOP_OUTER_LO]==k) | BHT_NO_ADDR_MATCH));
Branch 1.3
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`ifndef RV_FPGA_OPTIMIZE
rvclkhdr bht_bank_grp_cgc ( .en(bht_bank_clken[i][k]), .l1clk(bht_bank_clk[i][k]), .* ); // ifndef RV_FPGA_OPTIMIZE
`endif
Initial checkin.
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for (j=0 ; j<NUM_BHT_LOOP ; j++) begin : BHT_FLOPS
assign bht_bank_sel[i][k][j] = (bht_wr_en0[i] & (bht_wr_addr0[NUM_BHT_LOOP_INNER_HI :pt.BHT_ADDR_LO] == j) & ((bht_wr_addr0[pt.BHT_ADDR_HI: NUM_BHT_LOOP_OUTER_LO]==k) | BHT_NO_ADDR_MATCH)) |
(bht_wr_en2[i] & (bht_wr_addr2[NUM_BHT_LOOP_INNER_HI :pt.BHT_ADDR_LO] == j) & ((bht_wr_addr2[pt.BHT_ADDR_HI: NUM_BHT_LOOP_OUTER_LO]==k) | BHT_NO_ADDR_MATCH)) ;
assign bht_bank_wr_data[i][k][j] = (bht_wr_en2[i] & (bht_wr_addr2[NUM_BHT_LOOP_INNER_HI:pt.BHT_ADDR_LO] == j) & ((bht_wr_addr2[pt.BHT_ADDR_HI: NUM_BHT_LOOP_OUTER_LO]==k) | BHT_NO_ADDR_MATCH)) ? bht_wr_data2[1:0] :
bht_wr_data0[1:0] ;
Branch 1.3
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rvdffs_fpga #(2) bht_bank (.*,
Initial checkin.
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.clk (bht_bank_clk[i][k]),
.en (bht_bank_sel[i][k][j]),
Branch 1.3
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.rawclk (clk),
.clken (bht_bank_sel[i][k][j]),
Initial checkin.
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.din (bht_bank_wr_data[i][k][j]),
.dout (bht_bank_rd_data_out[i][(16*k)+j]));
end // block: BHT_FLOPS
end // block: BHT_CLK_GROUP
end // block: BANKS
always_comb begin : BHT_rd_mux
bht_bank0_rd_data_f[1:0] = '0 ;
bht_bank1_rd_data_f[1:0] = '0 ;
bht_bank0_rd_data_p1_f[1:0] = '0 ;
for (int j=0; j< pt.BHT_ARRAY_DEPTH; j++) begin
if (bht_rd_addr_f[pt.BHT_ADDR_HI:pt.BHT_ADDR_LO] == (pt.BHT_ADDR_HI-pt.BHT_ADDR_LO+1)'(j)) begin
bht_bank0_rd_data_f[1:0] = bht_bank_rd_data_out[0][j];
bht_bank1_rd_data_f[1:0] = bht_bank_rd_data_out[1][j];
end
if (bht_rd_addr_p1_f[pt.BHT_ADDR_HI:pt.BHT_ADDR_LO] == (pt.BHT_ADDR_HI-pt.BHT_ADDR_LO+1)'(j)) begin
bht_bank0_rd_data_p1_f[1:0] = bht_bank_rd_data_out[0][j];
end
end
end // block: BHT_rd_mux
function [1:0] countones;
input [1:0] valid;
begin
countones[1:0] = {2'b0, valid[1]} +
{2'b0, valid[0]};
end
endfunction
endmodule // el2_ifu_bp_ctl