riscv/rocket-chip
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clean up bypassing/hazard checking a bit

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This commit is contained in:
Andrew Waterman 2012-02-06 17:26:45 -08:00
parent 41c4e10c37
commit fde8e3b696
2 changed files with 23 additions and 30 deletions
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31
rocket/src/main/scala/ctrl.scala
View File

@ -60,7 +60,6 @@ class ioCtrlDpath extends Bundle()
val div_result_val = Bool(INPUT);
val mul_rdy = Bool(INPUT);
val mul_result_val = Bool(INPUT);
val mem_lu_bypass = Bool(INPUT);
val ex_waddr = UFix(5,INPUT); // write addr from execute stage
val mem_waddr = UFix(5,INPUT); // write addr from memory stage
val wb_waddr = UFix(5,INPUT); // write addr from writeback stage
@ -324,6 +323,7 @@ class rocketCtrl extends Component
val id_reg_xcpt_ma_inst = Reg(resetVal = Bool(false));
val id_reg_icmiss = Reg(resetVal = Bool(false));
val id_reg_replay = Reg(resetVal = Bool(false));
val id_load_use = Wire(){Bool()};
val ex_reg_br_type = Reg(){UFix(width = 4)};
val ex_reg_btb_hit = Reg(){Bool()};
@ -344,7 +344,7 @@ class rocketCtrl extends Component
val ex_reg_xcpt_fpu = Reg(resetVal = Bool(false));
val ex_reg_xcpt_syscall = Reg(resetVal = Bool(false));
val ex_reg_replay = Reg(resetVal = Bool(false));
val ex_reg_lu_bypass = Reg(resetVal = Bool(false));
val ex_reg_load_use = Reg(resetVal = Bool(false));
val mem_reg_inst_di = Reg(resetVal = Bool(false));
val mem_reg_inst_ei = Reg(resetVal = Bool(false));
@ -405,7 +405,7 @@ class rocketCtrl extends Component
ex_reg_xcpt_fpu <== Bool(false);
ex_reg_xcpt_syscall <== Bool(false);
ex_reg_replay <== Bool(false);
ex_reg_lu_bypass <== Bool(false);
ex_reg_load_use <== Bool(false);
}
otherwise {
ex_reg_br_type <== id_br_type;
@ -426,7 +426,7 @@ class rocketCtrl extends Component
ex_reg_xcpt_fpu <== Bool(false);
ex_reg_xcpt_syscall <== id_syscall.toBool;
ex_reg_replay <== id_reg_replay || ex_reg_replay_next;
ex_reg_lu_bypass <== io.dpath.mem_lu_bypass;
ex_reg_load_use <== id_load_use;
}
ex_reg_mem_cmd <== id_mem_cmd;
ex_reg_mem_type <== id_mem_type;
@ -565,7 +565,7 @@ class rocketCtrl extends Component
// replay execute stage PC when the D$ is blocked, when the D$ misses,
// for privileged instructions, and for fence.i instructions
val replay_ex = dcache_miss && ex_reg_lu_bypass || mem_reg_flush_inst ||
val replay_ex = dcache_miss && ex_reg_load_use || mem_reg_flush_inst ||
ex_reg_replay || ex_reg_mem_val && !(io.dmem.req_rdy && io.dtlb_rdy) ||
ex_reg_div_val && !io.dpath.div_rdy ||
ex_reg_mul_val && !io.dpath.mul_rdy
@ -604,13 +604,12 @@ class rocketCtrl extends Component
val ex_mem_cmd_load =
ex_reg_mem_val && ((ex_reg_mem_cmd === M_XRD) || ex_reg_mem_cmd(3).toBool);
val data_hazard_ex =
(ex_mem_cmd_load || ex_reg_div_val || ex_reg_mul_val) &&
((id_renx1.toBool && (id_raddr1 === io.dpath.ex_waddr)) ||
(id_renx2.toBool && (id_raddr2 === io.dpath.ex_waddr)) ||
(id_wen.toBool && (id_waddr === io.dpath.ex_waddr)));
val id_ex_hazard = data_hazard_ex && (ex_mem_cmd_load || ex_reg_div_val || ex_reg_mul_val)
// stall for RAW/WAW hazards on LB/LH and mul/div in memory stage.
// stall for WAW-but-not-RAW hazards on LW/LD/AMO.
val mem_mem_cmd_load =
mem_reg_mem_val && ((mem_reg_mem_cmd === M_XRD) || mem_reg_mem_cmd(3).toBool);
val mem_mem_cmd_load_bh =
@ -619,23 +618,19 @@ class rocketCtrl extends Component
(mem_reg_mem_type === MT_BU) ||
(mem_reg_mem_type === MT_H) ||
(mem_reg_mem_type === MT_HU));
val raw_hazard_mem =
(id_renx1.toBool && (id_raddr1 === io.dpath.mem_waddr)) ||
(id_renx2.toBool && (id_raddr2 === io.dpath.mem_waddr));
val waw_hazard_mem =
(id_wen.toBool && (id_waddr === io.dpath.mem_waddr));
val data_hazard_mem =
(mem_mem_cmd_load_bh || mem_reg_div_mul_val) && (raw_hazard_mem || waw_hazard_mem) ||
mem_mem_cmd_load && (!raw_hazard_mem && waw_hazard_mem)
(id_renx1.toBool && (id_raddr1 === io.dpath.mem_waddr)) ||
(id_renx2.toBool && (id_raddr2 === io.dpath.mem_waddr)) ||
(id_wen.toBool && (id_waddr === io.dpath.mem_waddr));
val id_mem_hazard = data_hazard_mem && (mem_mem_cmd_load_bh || mem_reg_div_mul_val)
id_load_use := mem_mem_cmd_load && data_hazard_mem
// stall for RAW/WAW hazards on load/AMO misses and mul/div in writeback.
val data_hazard_wb =
(dcache_miss || wb_reg_div_mul_val) &&
((id_renx1.toBool && (id_raddr1 === io.dpath.wb_waddr)) ||
(id_renx2.toBool && (id_raddr2 === io.dpath.wb_waddr)) ||
(id_wen.toBool && (id_waddr === io.dpath.wb_waddr)));
val data_hazard = data_hazard_ex || data_hazard_mem || data_hazard_wb;
val id_wb_hazard = data_hazard_wb && (dcache_miss || wb_reg_div_mul_val)
// for divider, multiplier, load miss writeback
val mem_wb = Reg(io.dmem.resp_replay, resetVal = Bool(false)) // delayed for subword extension
@ -645,7 +640,7 @@ class rocketCtrl extends Component
val ctrl_stalld =
!take_pc &&
(
data_hazard ||
id_ex_hazard || id_mem_hazard || id_wb_hazard ||
id_renx2.toBool && id_stall_raddr2 ||
id_renx1.toBool && id_stall_raddr1 ||
id_wen.toBool && id_stall_waddr ||

16
rocket/src/main/scala/dpath.scala
View File

@ -106,6 +106,7 @@ class rocketDpath extends Component
val mem_reg_ctrl_div_val = Reg(resetVal = Bool(false));
val mem_reg_ctrl_wen = Reg(resetVal = Bool(false));
val mem_reg_ctrl_wen_pcr = Reg(resetVal = Bool(false));
val mem_wdata = Wire() { Bits() };
// writeback definitions
val wb_reg_valid = Reg(resetVal = Bool(false));
@ -205,26 +206,21 @@ class rocketDpath extends Component
UFix(0, 5))))));
// bypass muxes
val rs1_mem_lu_bypass = id_raddr1 != UFix(0, 5) && io.ctrl.mem_load && id_raddr1 === mem_reg_waddr;
val id_rs1 =
Mux(r_dmem_resp_replay, io.dmem.resp_data_subword,
Mux(io.ctrl.div_wb, div_result,
Mux(io.ctrl.mul_wb, mul_result,
Mux(id_raddr1 != UFix(0, 5) && (ex_reg_ctrl_wen || ex_reg_ctrl_ll_wb) && id_raddr1 === ex_reg_waddr, ex_wdata,
Mux(rs1_mem_lu_bypass, io.dmem.resp_data,
Mux(id_raddr1 != UFix(0, 5) && (mem_reg_ctrl_wen || mem_reg_ctrl_ll_wb) && id_raddr1 === mem_reg_waddr, mem_reg_wdata,
Mux(id_raddr1 != UFix(0, 5) && (mem_reg_ctrl_wen || mem_reg_ctrl_ll_wb) && id_raddr1 === mem_reg_waddr, mem_wdata,
Mux(id_raddr1 != UFix(0, 5) && (wb_reg_ctrl_wen || wb_reg_ctrl_ll_wb) && id_raddr1 === wb_reg_waddr, wb_wdata,
id_rdata1)))))));
id_rdata1))))));
val rs2_mem_lu_bypass = id_raddr2 != UFix(0, 5) && io.ctrl.mem_load && id_raddr2 === mem_reg_waddr;
val id_rs2 =
Mux(id_raddr2 != UFix(0, 5) && (ex_reg_ctrl_wen || ex_reg_ctrl_ll_wb) && id_raddr2 === ex_reg_waddr, ex_wdata,
Mux(rs2_mem_lu_bypass, io.dmem.resp_data,
Mux(id_raddr2 != UFix(0, 5) && (mem_reg_ctrl_wen || mem_reg_ctrl_ll_wb) && id_raddr2 === mem_reg_waddr, mem_reg_wdata,
Mux(id_raddr2 != UFix(0, 5) && (mem_reg_ctrl_wen || mem_reg_ctrl_ll_wb) && id_raddr2 === mem_reg_waddr, mem_wdata,
Mux(id_raddr2 != UFix(0, 5) && (wb_reg_ctrl_wen || wb_reg_ctrl_ll_wb) && id_raddr2 === wb_reg_waddr, wb_wdata,
id_rdata2))));
id_rdata2)));
io.ctrl.mem_lu_bypass := rs1_mem_lu_bypass || rs2_mem_lu_bypass;
io.ctrl.inst := id_reg_inst;
// execute stage
@ -378,6 +374,8 @@ class rocketDpath extends Component
io.ctrl.mem_waddr := mem_reg_waddr;
io.ctrl.mem_valid := mem_reg_valid;
mem_wdata := Mux(io.ctrl.mem_load, io.dmem.resp_data, mem_reg_wdata)
// 32/64 bit load handling (moved to earlier in file)
// writeback stage