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fix prediction shift for BHT and BTB (#1337)

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* add labels to if/else blocks for branch prediction

* add labels to if/else blocks for caches

* fix prediction shift for BHT and BTB
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Côme 2023-08-18 10:26:26 +02:00 • committed by GitHub
parent fa59fff204
commit 18766f186e
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2 changed files with 12 additions and 8 deletions
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4
core/cva6.sv
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@ -834,7 +834,7 @@ module cva6 import ariane_pkg::*; #(
// Cache Subsystem
// -------------------
if (DCACHE_TYPE == int'(cva6_config_pkg::WT)) begin
if (DCACHE_TYPE == int'(cva6_config_pkg::WT)) begin : gen_cache_wt
// this is a cache subsystem that is compatible with OpenPiton
wt_cache_subsystem #(
.CVA6Cfg ( CVA6Cfg ),
@ -876,7 +876,7 @@ module cva6 import ariane_pkg::*; #(
.inval_valid_i ( inval_valid ),
.inval_ready_o ( inval_ready )
);
end else begin
end else begin : gen_cache_wb
std_cache_subsystem #(
// note: this only works with one cacheable region

16
core/frontend/frontend.sv
View file

@ -126,22 +126,26 @@ module frontend import ariane_pkg::*; #(
.addr_o ( addr ),
.instr_o ( instr )
);
// --------------------
// Branch Prediction
// --------------------
// select the right branch prediction result
// in case we are serving an unaligned instruction in instr[0] we need to take
// the prediction we saved from the previous fetch
assign bht_prediction_shifted[0] = (serving_unaligned) ? bht_q : bht_prediction[addr[0][1]];
assign btb_prediction_shifted[0] = (serving_unaligned) ? btb_q : btb_prediction[addr[0][1]];
if (ariane_pkg::RVC) begin : gen_btb_prediction_shifted
assign bht_prediction_shifted[0] = (serving_unaligned) ? bht_q : bht_prediction[addr[0][$clog2(INSTR_PER_FETCH):1]];
assign btb_prediction_shifted[0] = (serving_unaligned) ? btb_q : btb_prediction[addr[0][$clog2(INSTR_PER_FETCH):1]];
// for all other predictions we can use the generated address to index
// into the branch prediction data structures
for (genvar i = 1; i < INSTR_PER_FETCH; i++) begin : gen_prediction_address
assign bht_prediction_shifted[i] = bht_prediction[addr[i][$clog2(INSTR_PER_FETCH):1]];
assign btb_prediction_shifted[i] = btb_prediction[addr[i][$clog2(INSTR_PER_FETCH):1]];
end
end else begin
assign bht_prediction_shifted[0] = (serving_unaligned) ? bht_q : bht_prediction[addr[0][1]];
assign btb_prediction_shifted[0] = (serving_unaligned) ? btb_q : btb_prediction[addr[0][1]];
end;
// for the return address stack it doens't matter as we have the
@ -394,7 +398,7 @@ module frontend import ariane_pkg::*; #(
if (ArianeCfg.RASDepth == 0) begin
assign ras_predict = '0;
end else begin
end else begin : ras_gen
ras #(
.DEPTH ( ArianeCfg.RASDepth )
) i_ras (
@ -415,7 +419,7 @@ module frontend import ariane_pkg::*; #(
if (ArianeCfg.BTBEntries == 0) begin
assign btb_prediction = '0;
end else begin
end else begin : btb_gen
btb #(
.NR_ENTRIES ( ArianeCfg.BTBEntries )
) i_btb (
@ -431,7 +435,7 @@ module frontend import ariane_pkg::*; #(
if (ArianeCfg.BHTEntries == 0) begin
assign bht_prediction = '0;
end else begin
end else begin : bht_gen
bht #(
.NR_ENTRIES ( ArianeCfg.BHTEntries )
) i_bht (