riscv/rocket-chip
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arbitrate for LLFU writebacks in MEM stage

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This commit is contained in:
Andrew Waterman 2012-02-08 04:21:05 -08:00
parent ebed56500e
commit d471a8b2da
3 changed files with 50 additions and 55 deletions
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24
rocket/src/main/scala/ctrl.scala
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@ -26,10 +26,8 @@ class ioCtrlDpath extends Bundle()
val fn_alu = UFix(4, OUTPUT); val fn_alu = UFix(4, OUTPUT);
val mul_val = Bool(OUTPUT); val mul_val = Bool(OUTPUT);
val mul_fn = UFix(2, OUTPUT); val mul_fn = UFix(2, OUTPUT);
val mul_wb = Bool(OUTPUT);
val div_val = Bool(OUTPUT); val div_val = Bool(OUTPUT);
val div_fn = UFix(2, OUTPUT); val div_fn = UFix(2, OUTPUT);
val div_wb = Bool(OUTPUT);
val sel_wa = Bool(OUTPUT); val sel_wa = Bool(OUTPUT);
val sel_wb = UFix(3, OUTPUT); val sel_wb = UFix(3, OUTPUT);
val ren_pcr = Bool(OUTPUT); val ren_pcr = Bool(OUTPUT);
@ -343,7 +341,7 @@ class rocketCtrl extends Component
ex_reg_div_val <== id_div_val.toBool; ex_reg_div_val <== id_div_val.toBool;
ex_reg_mul_val <== id_mul_val.toBool; ex_reg_mul_val <== id_mul_val.toBool;
ex_reg_mem_val <== id_mem_val.toBool; ex_reg_mem_val <== id_mem_val.toBool;
ex_reg_wen <== id_wen.toBool; ex_reg_wen <== id_wen.toBool && id_waddr != UFix(0);
ex_reg_fp_wen <== fpdec.io.wen; ex_reg_fp_wen <== fpdec.io.wen;
ex_reg_eret <== id_eret.toBool; ex_reg_eret <== id_eret.toBool;
ex_reg_replay_next <== id_replay_next.toBool; ex_reg_replay_next <== id_replay_next.toBool;
@ -533,10 +531,11 @@ class rocketCtrl extends Component
val take_pc_wb = wb_reg_replay || wb_reg_exception || wb_reg_eret; val take_pc_wb = wb_reg_replay || wb_reg_exception || wb_reg_eret;
take_pc <== take_pc_ex || take_pc_wb; take_pc <== take_pc_ex || take_pc_wb;
// replay mem stage PC on a DTLB miss // replay mem stage PC on a DTLB miss or a long-latency writeback
val replay_mem = io.dtlb_miss || io.dmem.resp_nack || mem_reg_replay; val mem_ll_wb = io.dpath.mem_wb || io.dpath.mul_result_val || io.dpath.div_result_val
val kill_mem = io.dtlb_miss || io.dmem.resp_nack || take_pc_wb || mem_exception || mem_reg_kill; val replay_mem = io.dtlb_miss || mem_reg_wen && mem_ll_wb || io.dmem.resp_nack || mem_reg_replay
val kill_dcache = io.dtlb_miss || take_pc_wb || mem_exception || mem_reg_kill; val kill_mem = io.dtlb_miss || mem_reg_wen && mem_ll_wb || io.dmem.resp_nack || take_pc_wb || mem_exception || mem_reg_kill
val kill_dcache = io.dtlb_miss || mem_reg_wen && mem_ll_wb || take_pc_wb || mem_exception || mem_reg_kill
// replay execute stage PC when the D$ is blocked, when the D$ misses, // replay execute stage PC when the D$ is blocked, when the D$ misses,
// for privileged instructions, and for fence.i instructions // for privileged instructions, and for fence.i instructions
@ -617,10 +616,6 @@ class rocketCtrl extends Component
val id_wb_hazard = data_hazard_wb && (wb_reg_dcache_miss || wb_reg_div_mul_val) || val id_wb_hazard = data_hazard_wb && (wb_reg_dcache_miss || wb_reg_div_mul_val) ||
fp_data_hazard_wb && wb_reg_dcache_miss fp_data_hazard_wb && wb_reg_dcache_miss
// for divider, multiplier, load miss writeback
val mul_wb = io.dpath.mul_result_val && !io.dpath.mem_wb;
val div_wb = io.dpath.div_result_val && !io.dpath.mul_result_val && !io.dpath.mem_wb;
val ctrl_stalld = val ctrl_stalld =
!take_pc && !take_pc &&
( (
@ -629,10 +624,7 @@ class rocketCtrl extends Component
id_stall_fpu || id_stall_fpu ||
id_mem_val.toBool && !(io.dmem.req_rdy && io.dtlb_rdy) || id_mem_val.toBool && !(io.dmem.req_rdy && io.dtlb_rdy) ||
((id_sync === SYNC_D) || (id_sync === SYNC_I)) && !io.dmem.req_rdy || ((id_sync === SYNC_D) || (id_sync === SYNC_I)) && !io.dmem.req_rdy ||
id_console_out_val && !io.console.rdy || id_console_out_val && !io.console.rdy
io.dpath.div_result_val ||
io.dpath.mul_result_val ||
io.dpath.mem_wb
); );
val ctrl_stallf = ctrl_stalld; val ctrl_stallf = ctrl_stalld;
@ -658,10 +650,8 @@ class rocketCtrl extends Component
io.dpath.fn_alu := id_fn_alu; io.dpath.fn_alu := id_fn_alu;
io.dpath.div_fn := id_div_fn; io.dpath.div_fn := id_div_fn;
io.dpath.div_val := id_div_val.toBool; io.dpath.div_val := id_div_val.toBool;
io.dpath.div_wb := div_wb;
io.dpath.mul_fn := id_mul_fn; io.dpath.mul_fn := id_mul_fn;
io.dpath.mul_val := id_mul_val.toBool; io.dpath.mul_val := id_mul_val.toBool;
io.dpath.mul_wb := mul_wb;
io.dpath.ex_fp_val:= ex_reg_fp_val; io.dpath.ex_fp_val:= ex_reg_fp_val;
io.dpath.ex_wen := ex_reg_wen; io.dpath.ex_wen := ex_reg_wen;
io.dpath.mem_wen := mem_reg_wen; io.dpath.mem_wen := mem_reg_wen;

76
rocket/src/main/scala/dpath.scala
View File

@ -85,7 +85,6 @@ class rocketDpath extends Component
val ex_reg_ctrl_eret = Reg(resetVal = Bool(false)); val ex_reg_ctrl_eret = Reg(resetVal = Bool(false));
val ex_reg_ctrl_fn_dw = Reg() { UFix() }; val ex_reg_ctrl_fn_dw = Reg() { UFix() };
val ex_reg_ctrl_fn_alu = Reg() { UFix() }; val ex_reg_ctrl_fn_alu = Reg() { UFix() };
val ex_reg_ctrl_ll_wb = Reg(resetVal = Bool(false));
val ex_reg_ctrl_mul_val = Reg(resetVal = Bool(false)); val ex_reg_ctrl_mul_val = Reg(resetVal = Bool(false));
val ex_reg_ctrl_mul_fn = Reg() { UFix() }; val ex_reg_ctrl_mul_fn = Reg() { UFix() };
val ex_reg_ctrl_div_val = Reg(resetVal = Bool(false)); val ex_reg_ctrl_div_val = Reg(resetVal = Bool(false));
@ -101,7 +100,6 @@ class rocketDpath extends Component
val mem_reg_waddr = Reg() { UFix() }; val mem_reg_waddr = Reg() { UFix() };
val mem_reg_wdata = Reg() { Bits() }; val mem_reg_wdata = Reg() { Bits() };
val mem_reg_raddr2 = Reg() { UFix() }; val mem_reg_raddr2 = Reg() { UFix() };
val mem_reg_ctrl_ll_wb = Reg(resetVal = Bool(false));
val mem_reg_ctrl_mul_val = Reg(resetVal = Bool(false)); val mem_reg_ctrl_mul_val = Reg(resetVal = Bool(false));
val mem_reg_ctrl_div_val = Reg(resetVal = Bool(false)); val mem_reg_ctrl_div_val = Reg(resetVal = Bool(false));
val mem_reg_ctrl_wen_pcr = Reg(resetVal = Bool(false)); val mem_reg_ctrl_wen_pcr = Reg(resetVal = Bool(false));
@ -113,10 +111,11 @@ class rocketDpath extends Component
val wb_reg_waddr = Reg() { UFix() }; val wb_reg_waddr = Reg() { UFix() };
val wb_reg_wdata = Reg() { Bits() }; val wb_reg_wdata = Reg() { Bits() };
val wb_reg_raddr2 = Reg() { UFix() }; val wb_reg_raddr2 = Reg() { UFix() };
val wb_reg_ctrl_ll_wb = Reg(resetVal = Bool(false));
val wb_reg_ctrl_wen_pcr = Reg(resetVal = Bool(false)); val wb_reg_ctrl_wen_pcr = Reg(resetVal = Bool(false));
val wb_reg_ll_wb = Reg(resetVal = Bool(false));
val wb_wdata = Wire() { Bits() }; val wb_wdata = Wire() { Bits() };
val dmem_resp_replay = Wire() { Bool() }
val r_dmem_resp_replay = Reg(resetVal = Bool(false)); val r_dmem_resp_replay = Reg(resetVal = Bool(false));
val r_dmem_fp_replay = Reg(resetVal = Bool(false)); val r_dmem_fp_replay = Reg(resetVal = Bool(false));
val r_dmem_resp_waddr = Reg() { UFix() }; val r_dmem_resp_waddr = Reg() { UFix() };
@ -194,29 +193,21 @@ class rocketDpath extends Component
val id_rdata1 = rfile.io.r1.data; val id_rdata1 = rfile.io.r1.data;
// destination register selection // destination register selection
val id_ctrl_ll_wb = io.ctrl.div_wb || io.ctrl.mul_wb || r_dmem_resp_replay;
val id_waddr = val id_waddr =
Mux(r_dmem_resp_replay, r_dmem_resp_waddr,
Mux(io.ctrl.mul_wb, mul_result_tag,
Mux(io.ctrl.div_wb, div_result_tag,
Mux(io.ctrl.sel_wa === WA_RD, id_reg_inst(31,27).toUFix, Mux(io.ctrl.sel_wa === WA_RD, id_reg_inst(31,27).toUFix,
Mux(io.ctrl.sel_wa === WA_RA, RA, RA); // WA_RA
UFix(0, 5))))));
// bypass muxes // bypass muxes
val id_rs1 = val id_rs1 =
Mux(r_dmem_resp_replay, io.dmem.resp_data_subword, Mux(io.ctrl.ex_wen && id_raddr1 === ex_reg_waddr, ex_wdata,
Mux(io.ctrl.div_wb, div_result, Mux(io.ctrl.mem_wen && id_raddr1 === mem_reg_waddr, mem_wdata,
Mux(io.ctrl.mul_wb, mul_result, Mux((io.ctrl.wb_wen || wb_reg_ll_wb) && id_raddr1 === wb_reg_waddr, wb_wdata,
Mux(id_raddr1 != UFix(0, 5) && (io.ctrl.ex_wen || ex_reg_ctrl_ll_wb) && id_raddr1 === ex_reg_waddr, ex_wdata, id_rdata1)));
Mux(id_raddr1 != UFix(0, 5) && (io.ctrl.mem_wen || mem_reg_ctrl_ll_wb) && id_raddr1 === mem_reg_waddr, mem_wdata,
Mux(id_raddr1 != UFix(0, 5) && (io.ctrl.wb_wen || wb_reg_ctrl_ll_wb) && id_raddr1 === wb_reg_waddr, wb_wdata,
id_rdata1))))));
val id_rs2 = val id_rs2 =
Mux(id_raddr2 != UFix(0, 5) && (io.ctrl.ex_wen || ex_reg_ctrl_ll_wb) && id_raddr2 === ex_reg_waddr, ex_wdata, Mux(io.ctrl.ex_wen && id_raddr2 === ex_reg_waddr, ex_wdata,
Mux(id_raddr2 != UFix(0, 5) && (io.ctrl.mem_wen || mem_reg_ctrl_ll_wb) && id_raddr2 === mem_reg_waddr, mem_wdata, Mux(io.ctrl.mem_wen && id_raddr2 === mem_reg_waddr, mem_wdata,
Mux(id_raddr2 != UFix(0, 5) && (io.ctrl.wb_wen || wb_reg_ctrl_ll_wb) && id_raddr2 === wb_reg_waddr, wb_wdata, Mux((io.ctrl.wb_wen || wb_reg_ll_wb) && id_raddr2 === wb_reg_waddr, wb_wdata,
id_rdata2))); id_rdata2)));
io.ctrl.inst := id_reg_inst; io.ctrl.inst := id_reg_inst;
@ -234,7 +225,6 @@ class rocketDpath extends Component
ex_reg_ctrl_fn_alu <== io.ctrl.fn_alu; ex_reg_ctrl_fn_alu <== io.ctrl.fn_alu;
ex_reg_ctrl_mul_fn <== io.ctrl.mul_fn; ex_reg_ctrl_mul_fn <== io.ctrl.mul_fn;
ex_reg_ctrl_div_fn <== io.ctrl.div_fn; ex_reg_ctrl_div_fn <== io.ctrl.div_fn;
ex_reg_ctrl_ll_wb <== id_ctrl_ll_wb;
ex_reg_ctrl_sel_wb <== io.ctrl.sel_wb; ex_reg_ctrl_sel_wb <== io.ctrl.sel_wb;
ex_reg_ctrl_ren_pcr <== io.ctrl.ren_pcr; ex_reg_ctrl_ren_pcr <== io.ctrl.ren_pcr;
@ -280,7 +270,7 @@ class rocketDpath extends Component
div.io.div_waddr := ex_reg_waddr; div.io.div_waddr := ex_reg_waddr;
div.io.dpath_rs1 := ex_reg_rs1; div.io.dpath_rs1 := ex_reg_rs1;
div.io.dpath_rs2 := ex_reg_rs2; div.io.dpath_rs2 := ex_reg_rs2;
div.io.div_result_rdy := io.ctrl.div_wb; div.io.div_result_rdy := !dmem_resp_replay
io.ctrl.div_rdy := div.io.div_rdy; io.ctrl.div_rdy := div.io.div_rdy;
io.ctrl.div_result_val := div.io.div_result_val; io.ctrl.div_result_val := div.io.div_result_val;
@ -296,7 +286,7 @@ class rocketDpath extends Component
io.ctrl.mul_rdy := mul.io.mul_rdy io.ctrl.mul_rdy := mul.io.mul_rdy
io.ctrl.mul_result_val := mul.io.result_val; io.ctrl.mul_result_val := mul.io.result_val;
mul.io.result_rdy := io.ctrl.mul_wb mul.io.result_rdy := !dmem_resp_replay && !div.io.div_result_val
io.ctrl.ex_waddr := ex_reg_waddr; // for load/use hazard detection & bypass control io.ctrl.ex_waddr := ex_reg_waddr; // for load/use hazard detection & bypass control
@ -345,7 +335,7 @@ class rocketDpath extends Component
// writeback select mux // writeback select mux
ex_wdata := ex_wdata :=
Mux(ex_reg_ctrl_ll_wb || ex_reg_ctrl_wen_pcr, ex_reg_rs1, Mux(ex_reg_ctrl_wen_pcr, ex_reg_rs1,
Mux(ex_reg_ctrl_sel_wb === WB_PC, Cat(Fill(64-VADDR_BITS, ex_pc_plus4(VADDR_BITS-1)), ex_pc_plus4), Mux(ex_reg_ctrl_sel_wb === WB_PC, Cat(Fill(64-VADDR_BITS, ex_pc_plus4(VADDR_BITS-1)), ex_pc_plus4),
Mux(ex_reg_ctrl_sel_wb === WB_PCR, ex_pcr, Mux(ex_reg_ctrl_sel_wb === WB_PCR, ex_pcr,
Mux(ex_reg_ctrl_sel_wb === WB_TSC, tsc_reg, Mux(ex_reg_ctrl_sel_wb === WB_TSC, tsc_reg,
@ -356,7 +346,6 @@ class rocketDpath extends Component
mem_reg_pc <== ex_reg_pc; mem_reg_pc <== ex_reg_pc;
mem_reg_waddr <== ex_reg_waddr; mem_reg_waddr <== ex_reg_waddr;
mem_reg_wdata <== ex_wdata; mem_reg_wdata <== ex_wdata;
mem_reg_ctrl_ll_wb <== ex_reg_ctrl_ll_wb;
mem_reg_raddr2 <== ex_reg_raddr2; mem_reg_raddr2 <== ex_reg_raddr2;
mem_reg_ctrl_mul_val <== ex_reg_ctrl_mul_val; mem_reg_ctrl_mul_val <== ex_reg_ctrl_mul_val;
mem_reg_ctrl_div_val <== ex_reg_ctrl_div_val; mem_reg_ctrl_div_val <== ex_reg_ctrl_div_val;
@ -380,14 +369,26 @@ class rocketDpath extends Component
// writeback stage // writeback stage
val dmem_resp_fpu = if (HAVE_FPU) io.dmem.resp_tag(0).toBool else Bool(false) val dmem_resp_fpu = if (HAVE_FPU) io.dmem.resp_tag(0).toBool else Bool(false)
r_dmem_resp_replay <== io.dmem.resp_replay && !dmem_resp_fpu; val dmem_resp_waddr = io.dmem.resp_tag.toUFix >> UFix(1)
dmem_resp_replay := io.dmem.resp_replay && !dmem_resp_fpu;
r_dmem_resp_replay <== dmem_resp_replay
r_dmem_resp_waddr <== dmem_resp_waddr
r_dmem_fp_replay <== io.dmem.resp_replay && dmem_resp_fpu; r_dmem_fp_replay <== io.dmem.resp_replay && dmem_resp_fpu;
r_dmem_resp_waddr <== io.dmem.resp_tag.toUFix >> UFix(1)
val mem_ll_waddr = Mux(dmem_resp_replay, dmem_resp_waddr,
Mux(div_result_val, div_result_tag,
Mux(mul_result_val, mul_result_tag,
mem_reg_waddr)))
val mem_ll_wdata = Mux(div_result_val, div_result,
Mux(mul_result_val, mul_result,
mem_reg_wdata))
val mem_ll_wb = mem_ll_waddr != UFix(0) &&
(dmem_resp_replay || div_result_val || mul_result_val)
wb_reg_pc <== mem_reg_pc; wb_reg_pc <== mem_reg_pc;
wb_reg_waddr <== mem_reg_waddr; wb_reg_ll_wb <== mem_ll_wb
wb_reg_wdata <== mem_reg_wdata; wb_reg_waddr <== mem_ll_waddr
wb_reg_ctrl_ll_wb <== mem_reg_ctrl_ll_wb; wb_reg_wdata <== mem_ll_wdata
wb_reg_raddr2 <== mem_reg_raddr2; wb_reg_raddr2 <== mem_reg_raddr2;
when (io.ctrl.killm) { when (io.ctrl.killm) {
@ -400,19 +401,20 @@ class rocketDpath extends Component
} }
// regfile write // regfile write
wb_wdata := Mux(Reg(io.ctrl.mem_load), io.dmem.resp_data_subword, wb_reg_wdata) val wb_src_dmem = Reg(io.ctrl.mem_load) && wb_reg_valid || r_dmem_resp_replay
rfile.io.w0.addr := wb_reg_waddr; wb_wdata := Mux(wb_src_dmem, io.dmem.resp_data_subword, wb_reg_wdata)
rfile.io.w0.en := io.ctrl.wb_wen || wb_reg_ctrl_ll_wb; rfile.io.w0.addr := wb_reg_waddr
rfile.io.w0.en := io.ctrl.wb_wen || wb_reg_ll_wb
rfile.io.w0.data := wb_wdata rfile.io.w0.data := wb_wdata
io.ctrl.wb_waddr := wb_reg_waddr; io.ctrl.wb_waddr := wb_reg_waddr;
io.ctrl.mem_wb := r_dmem_resp_replay; io.ctrl.mem_wb := dmem_resp_replay;
// scoreboard clear (for div/mul and D$ load miss writebacks) // scoreboard clear (for div/mul and D$ load miss writebacks)
io.ctrl.sboard_clr := id_ctrl_ll_wb; io.ctrl.sboard_clr := mem_ll_wb
io.ctrl.sboard_clra := id_waddr; io.ctrl.sboard_clra := mem_ll_waddr
io.ctrl.fp_sboard_clr := r_dmem_fp_replay; io.ctrl.fp_sboard_clr := r_dmem_fp_replay
io.ctrl.fp_sboard_clra := r_dmem_resp_waddr; io.ctrl.fp_sboard_clra := r_dmem_resp_waddr
// processor control regfile write // processor control regfile write
pcr.io.w.addr := wb_reg_raddr2; pcr.io.w.addr := wb_reg_raddr2;

5
rocket/src/main/scala/fpu.scala
View File

@ -92,7 +92,10 @@ class rocketFPUDecoder extends Component
Array(FLW -> List(Y, Y, N, N, N), Array(FLW -> List(Y, Y, N, N, N),
FLD -> List(Y, Y, N, N, N), FLD -> List(Y, Y, N, N, N),
FSW -> List(Y, N, N, Y, N), FSW -> List(Y, N, N, Y, N),
FSD -> List(Y, N, N, Y, N))) FSD -> List(Y, N, N, Y, N),
MTFSR -> List(Y, N, N, N, N),
MFFSR -> List(Y, N, N, N, N)
))
val valid :: wen :: ren1 :: ren2 :: ren3 :: Nil = decoder val valid :: wen :: ren1 :: ren2 :: ren3 :: Nil = decoder
io.valid := valid.toBool io.valid := valid.toBool