diff options
Diffstat (limited to 'rv64cpu/rtl/core/hazard_unit.sv')
| -rw-r--r-- | rv64cpu/rtl/core/hazard_unit.sv | 18 |
1 files changed, 14 insertions, 4 deletions
diff --git a/rv64cpu/rtl/core/hazard_unit.sv b/rv64cpu/rtl/core/hazard_unit.sv index aef550c..ee90356 100644 --- a/rv64cpu/rtl/core/hazard_unit.sv +++ b/rv64cpu/rtl/core/hazard_unit.sv @@ -36,6 +36,7 @@ module hazard_unit input logic [4:0] ex_rd_addr, input logic ex_reg_write_en, input logic ex_is_load, + input logic ex_is_csr, input logic ex_branch_taken, input logic [XLEN-1:0] ex_branch_target, @@ -44,6 +45,8 @@ module hazard_unit // ----------------------- input logic [4:0] mem_rd_addr, input logic mem_reg_write_en, + input logic mem_result_late, + input logic mem_is_csr, input logic mem_stall_req, // D-Cache miss or memory busy // ----------------------- @@ -96,7 +99,7 @@ module hazard_unit // Operand A (ex_rs1_addr) always_comb begin - if (mem_reg_write_en && (mem_rd_addr != 5'b0) && (mem_rd_addr == ex_rs1_addr)) begin + if (mem_reg_write_en && !mem_result_late && (mem_rd_addr != 5'b0) && (mem_rd_addr == ex_rs1_addr)) begin forward_a_sel = 2'b01; // Forward from MEM stage end else if (wb_reg_write_en && (wb_rd_addr != 5'b0) && (wb_rd_addr == ex_rs1_addr)) begin forward_a_sel = 2'b10; // Forward from WB stage @@ -107,7 +110,7 @@ module hazard_unit // Operand B (ex_rs2_addr) always_comb begin - if (mem_reg_write_en && (mem_rd_addr != 5'b0) && (mem_rd_addr == ex_rs2_addr)) begin + if (mem_reg_write_en && !mem_result_late && (mem_rd_addr != 5'b0) && (mem_rd_addr == ex_rs2_addr)) begin forward_b_sel = 2'b01; // Forward from MEM stage end else if (wb_reg_write_en && (wb_rd_addr != 5'b0) && (wb_rd_addr == ex_rs2_addr)) begin forward_b_sel = 2'b10; // Forward from WB stage @@ -126,6 +129,12 @@ module hazard_unit assign load_use_stall = ex_is_load && (ex_rd_addr != 5'b0) && ((ex_rd_addr == id_rs1_addr) || (ex_rd_addr == id_rs2_addr)); + logic csr_use_stall; + assign csr_use_stall = ((ex_is_csr && ex_reg_write_en && (ex_rd_addr != 5'b0) && + ((ex_rd_addr == id_rs1_addr) || (ex_rd_addr == id_rs2_addr))) || + (mem_is_csr && mem_reg_write_en && (mem_rd_addr != 5'b0) && + ((mem_rd_addr == id_rs1_addr) || (mem_rd_addr == id_rs2_addr)))); + // ----------------------- // PC Redirect Selection (Trap has top priority) // ----------------------- @@ -168,8 +177,9 @@ module hazard_unit ex_mem_stall_en = 1'b1; end - // (2) Load-Use stall: freeze IF and IF/ID, insert bubble into ID/EX - if (load_use_stall && !mem_stall_req) begin + // (2) Value-use stall: freeze IF and IF/ID, insert bubble into ID/EX. + // Loads and CSR reads both produce their register result after EX. + if ((load_use_stall || csr_use_stall) && !mem_stall_req) begin if_stall_en = 1'b1; if_id_stall_en = 1'b1; id_ex_flush_en = 1'b1; |