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https://github.com/openhwgroup/cva5.git
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Store Queue refactor
Signed-off-by: Eric Matthews <ematthew@sfu.ca>
This commit is contained in:
Eric Matthews
parent
b5f792048b
commit
dea43dc7ca
2 changed files with 73 additions and 71 deletions
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@ -56,6 +56,8 @@ module load_store_queue //ID-based input buffer for Load/Store Unit
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sq_entry_t sq_entry;
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logic store_conflict;
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logic write_forwarded;
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lq_entry_t lq_data_in;
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lq_entry_t lq_data_out;
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@ -65,7 +67,7 @@ module load_store_queue //ID-based input buffer for Load/Store Unit
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//Implementation
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//Can accept requests so long as store queue is not needed or is not full
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assign lsq.full = lsq.data_in.store & sq.full;
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assign lsq.full = lsq.data_in.store & (sq.full | (~lsq.data_in.forwarded_store & write_forwarded));
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//Address hash for load-store collision checking
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addr_hash lsq_addr_hash (
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@ -116,6 +118,7 @@ module load_store_queue //ID-based input buffer for Load/Store Unit
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.prev_store_conflicts (lq_data_out.potential_store_conflicts),
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.store_conflict (store_conflict),
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.wb_snoop (wb_snoop),
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.write_forwarded (write_forwarded),
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.retire_ids (retire_ids),
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.retire_port_valid (retire_port_valid)
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);
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@ -47,6 +47,7 @@ module store_queue
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//Writeback snooping
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input wb_packet_t wb_snoop,
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output logic write_forwarded,
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//Retire
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input id_t retire_ids [RETIRE_PORTS],
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@ -63,16 +64,16 @@ module store_queue
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logic [CONFIG.SQ_DEPTH-1:0] valid;
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logic [CONFIG.SQ_DEPTH-1:0] valid_next;
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addr_hash_t [CONFIG.SQ_DEPTH-1:0] hashes;
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logic [CONFIG.SQ_DEPTH-1:0] data_needed;
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logic [CONFIG.SQ_DEPTH-1:0] released;
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id_t [CONFIG.SQ_DEPTH-1:0] ids;
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id_t [CONFIG.SQ_DEPTH-1:0] id_needed;
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load_check_count_t [CONFIG.SQ_DEPTH-1:0] load_check_count;
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logic [31:0] store_data_from_wb [CONFIG.SQ_DEPTH];
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logic [31:0] store_data [CONFIG.SQ_DEPTH];
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//LUTRAM-based memory blocks
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sq_entry_t sq_entry_in;
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(* ramstyle = "MLAB, no_rw_check" *) logic [$bits(sq_entry_t)-1:0] sq_entry [CONFIG.SQ_DEPTH];
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(* ramstyle = "MLAB, no_rw_check" *) id_t [CONFIG.SQ_DEPTH-1:0] ids;
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(* ramstyle = "MLAB, no_rw_check" *) logic [LOG2_SQ_DEPTH-1:0] sq_ids [MAX_IDS];
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sq_entry_t output_entry;
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load_check_count_t [CONFIG.SQ_DEPTH-1:0] load_check_count_next;
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@ -83,9 +84,6 @@ module store_queue
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logic [CONFIG.SQ_DEPTH-1:0] new_request_one_hot;
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logic [CONFIG.SQ_DEPTH-1:0] issued_one_hot;
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logic [CONFIG.SQ_DEPTH-1:0] wb_id_match;
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////////////////////////////////////////////////////
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//Implementation
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assign sq_index_next = sq_index +LOG2_SQ_DEPTH'(sq.push);
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@ -131,32 +129,24 @@ module store_queue
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forwarded_store : sq.data_in.forwarded_store,
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data : sq.data_in.data
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};
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always_ff @ (posedge clk) begin
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if (sq.push)
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sq_entry[sq_index] <= sq_entry_in;
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end
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//Hash mem
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always_ff @ (posedge clk) begin
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if (sq.push)
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hashes[sq_index] <= addr_hash;
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end
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lutram_1w_1r #(.WIDTH($bits(sq_entry_t)), .DEPTH(CONFIG.SQ_DEPTH))
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store_attr (
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.clk(clk),
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.waddr(sq_index),
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.raddr(sq_oldest),
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.ram_write(sq.push),
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.new_ram_data(sq_entry_in),
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.ram_data_out(output_entry)
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);
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//Keep count of the number of pending loads that might need a store result
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//Mask out any store completing on this cycle
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logic [CONFIG.SQ_DEPTH-1:0] new_load_waiting;
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logic [CONFIG.SQ_DEPTH-1:0] waiting_load_completed;
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always_comb begin
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for (int i = 0; i < CONFIG.SQ_DEPTH; i++) begin
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potential_store_conflicts[i] = (valid[i] & ~issued_one_hot[i]) & (addr_hash == hashes[i]);
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new_load_waiting[i] = potential_store_conflicts[i] & lq_push;
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waiting_load_completed[i] = prev_store_conflicts[i] & lq_pop;
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load_check_count_next[i] =
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load_check_count[i]
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+ LOG2_MAX_IDS'(new_load_waiting[i])
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- LOG2_MAX_IDS'(waiting_load_completed[i]);
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load_check_count_next[i] = load_check_count[i]
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+ (LOG2_MAX_IDS+1)'({potential_store_conflicts[i] & lq_push})
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- (LOG2_MAX_IDS+1)'({prev_store_conflicts[i] & lq_pop});
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end
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end
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always_ff @ (posedge clk) begin
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@ -170,86 +160,95 @@ module store_queue
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assign store_conflict = |(prev_store_conflicts & valid);
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////////////////////////////////////////////////////
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//ID Handling
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//sq_id to global_id mem
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//Register-based storage
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//IDs of stores
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//ID needed for forwarded data
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//Address hashes
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always_ff @ (posedge clk) begin
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if (sq.push)
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ids[sq_index] <= sq.data_in.id;
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end
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// global_id to sq_id mem
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always_ff @ (posedge clk) begin
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if (sq.push)
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sq_ids[sq.data_in.id] <= sq_index;
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end
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//waiting on ID mem
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always_ff @ (posedge clk) begin
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if (sq.push)
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id_needed[sq_index] <= sq.data_in.id_needed;
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for (int i = 0; i < CONFIG.SQ_DEPTH; i++) begin
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if (new_request_one_hot[i]) begin
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id_needed[i] <= sq.data_in.id_needed;
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ids[i] <= sq.data_in.id;
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hashes[i] <= addr_hash;
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end
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end
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end
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////////////////////////////////////////////////////
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//Release Handling
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logic [CONFIG.SQ_DEPTH-1:0] newly_released;
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logic [LOG2_SQ_DEPTH-1:0] store_released_index [RETIRE_PORTS];
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logic store_released [RETIRE_PORTS];
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always_comb begin
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newly_released = '0;
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for (int i = 0; i < RETIRE_PORTS; i++) begin
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store_released_index[i] = sq_ids[retire_ids[i]];
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store_released[i] = {1'b1, ids[store_released_index[i]]} == {retire_port_valid[i], retire_ids[i]};
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newly_released |= CONFIG.SQ_DEPTH'(store_released[i]) << store_released_index[i];
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end
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end
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always_ff @ (posedge clk) begin
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released <= (released | newly_released) & ~new_request_one_hot;
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for (int i = 0; i < CONFIG.SQ_DEPTH; i++)
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for (int j = 0; j < RETIRE_PORTS; j++)
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newly_released[i] |= {1'b1, ids[i]} == {retire_port_valid[j], retire_ids[j]};
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end
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assign sq.no_released_stores_pending = ~|(valid & released);
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always_ff @ (posedge clk) begin
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if (rst)
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released <= 0;
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else
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released <= (released | (newly_released & valid)) & ~issued_one_hot;
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end
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assign sq.no_released_stores_pending = ~|released;
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////////////////////////////////////////////////////
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//Forwarded Store Data
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//Forwarding and Store Data
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logic [CONFIG.SQ_DEPTH-1:0] write_forward;
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always_ff @ (posedge clk) begin
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wb_snoop_r <= wb_snoop;
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end
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always_comb begin
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for (int i = 0; i < CONFIG.SQ_DEPTH; i++)
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write_forward[i] = {1'b1, wb_snoop_r.valid, wb_snoop_r.id} == {data_needed[i], 1'b1, id_needed[i]};
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end
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assign write_forwarded = |write_forward;
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always_ff @ (posedge clk) begin
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if (rst)
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data_needed <= 0;
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else
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data_needed <= (data_needed | (new_request_one_hot & {CONFIG.SQ_DEPTH{sq.data_in.forwarded_store}})) & ~write_forward;
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end
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logic [31:0] data_in;
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assign data_in = (sq.push & ~sq.data_in.forwarded_store) ? sq.data_in.data : wb_snoop_r.data;
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always_ff @ (posedge clk) begin
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for (int i = 0; i < CONFIG.SQ_DEPTH; i++) begin
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if ({1'b0, wb_snoop_r.valid, wb_snoop_r.id} == {released[i], 1'b1, id_needed[i]})
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store_data_from_wb[i] <= wb_snoop_r.data;
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if (write_forward[i] | new_request_one_hot[i])
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store_data[i] <= data_in;
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end
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end
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////////////////////////////////////////////////////
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//Store Transaction Outputs
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logic [31:0] data_for_alignment;
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logic [31:0] sq_data;
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sq_entry_t output_entry;
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assign output_entry = sq_entry[sq_oldest];
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logic [31:0] data_pre_alignment;
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logic [31:0] sq_data_out;
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always_comb begin
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//Input: ABCD
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//Assuming aligned requests,
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//Possible byte selections: (A/C/D, B/D, C/D, D)
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data_for_alignment = output_entry.forwarded_store ? store_data_from_wb[sq_oldest] : output_entry.data;
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data_pre_alignment = store_data[sq_oldest];
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sq_data[7:0] = data_for_alignment[7:0];
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sq_data[15:8] = (output_entry.addr[1:0] == 2'b01) ? data_for_alignment[7:0] : data_for_alignment[15:8];
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sq_data[23:16] = (output_entry.addr[1:0] == 2'b10) ? data_for_alignment[7:0] : data_for_alignment[23:16];
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sq_data_out[7:0] = data_pre_alignment[7:0];
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sq_data_out[15:8] = (output_entry.addr[1:0] == 2'b01) ? data_pre_alignment[7:0] : data_pre_alignment[15:8];
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sq_data_out[23:16] = (output_entry.addr[1:0] == 2'b10) ? data_pre_alignment[7:0] : data_pre_alignment[23:16];
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case(output_entry.addr[1:0])
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2'b10 : sq_data[31:24] = data_for_alignment[15:8];
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2'b11 : sq_data[31:24] = data_for_alignment[7:0];
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default : sq_data[31:24] = data_for_alignment[31:24];
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2'b10 : sq_data_out[31:24] = data_pre_alignment[15:8];
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2'b11 : sq_data_out[31:24] = data_pre_alignment[7:0];
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default : sq_data_out[31:24] = data_pre_alignment[31:24];
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endcase
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end
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assign sq.valid = valid[sq_oldest] & released[sq_oldest];
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assign sq.valid = released[sq_oldest];
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assign sq.data_out = '{
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addr : output_entry.addr,
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be : output_entry.be,
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fn3 : output_entry.fn3,
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forwarded_store : output_entry.forwarded_store,
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data : sq_data
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data : sq_data_out
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};
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////////////////////////////////////////////////////
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