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branch fix and conversion to writeback id bank

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This commit is contained in:
Eric Matthews 2019-08-18 15:26:44 -07:00
parent e3ee58c74f
commit b45de30452
1 changed files with 11 additions and 24 deletions
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35
core/branch_unit.sv
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@ -82,6 +82,8 @@ module branch_unit(
logic is_call;
logic is_return;
logic [31:0] rd_bank [MAX_INFLIGHT_COUNT-1:0];
instruction_id_t id;
//implementation
////////////////////////////////////////////////////
@ -166,35 +168,23 @@ module branch_unit(
assign ras.push = is_call;
assign ras.pop = is_return;
assign ras.new_addr = rd_ex;
assign ras.new_addr = njump_pc;
end
endgenerate
//WB Output
////////////////////////////////////////////////////
//if the destination reg is zero, the result is not "written back" to the register file.
//Output bank
assign new_jal_jalr_dec_with_rd = branch_ex.new_request_dec & branch_inputs.uses_rd;
always_ff @(posedge clk) begin
if (branch_ex.possible_issue & branch_inputs.uses_rd) begin
rd_ex <= pc_plus_4;
end
end
always_ff @ (posedge clk) begin
if (new_jal_jalr_dec_with_rd)
rd_bank[branch_ex.instruction_id] <= pc_plus_4;
end
assign branch_ex.ready = ~done | (done & branch_wb.accepted);
assign branch_wb.rd = rd_ex;
assign branch_ex.ready = 1;
assign branch_wb.rd = rd_bank[branch_wb.writeback_instruction_id];
always_ff @(posedge clk) begin
if (rst) begin
done <= 0;
end else if (branch_ex.new_request_dec & branch_inputs.uses_rd) begin
done <= 1;
end else if (branch_wb.accepted) begin
done <= 0;
end
end
assign branch_wb.done_next_cycle = branch_ex.new_request_dec & branch_inputs.uses_rd;
assign branch_wb.done_next_cycle = new_jal_jalr_dec_with_rd;
assign branch_wb.instruction_id = branch_ex.instruction_id;
////////////////////////////////////////////////////
@ -203,9 +193,6 @@ module branch_unit(
////////////////////////////////////////////////////
//Assertions
always_ff @ (posedge clk) begin
assert (~branch_wb.accepted | (branch_wb.accepted & done)) else $error("Spurious ack for Branch Unit");
end
////////////////////////////////////////////////////
//Trace Interface