riscv/rocket-chip
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fix mul/div kill bug

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occasionally, an in-progress multiply or divide could be
erroneously killed, tying up the register forever.
This commit is contained in:
Andrew Waterman 2012-02-09 02:26:03 -08:00
parent 128ec567ed
commit 92493ad153
3 changed files with 5 additions and 10 deletions
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2
rocket/src/main/scala/divider.scala
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@ -56,7 +56,7 @@ class rocketDivider(width : Int) extends Component {
val tc = (io.div_fn === DIV_D) || (io.div_fn === DIV_R); val tc = (io.div_fn === DIV_D) || (io.div_fn === DIV_R);
when (io.div_kill) { when (io.div_kill && Reg(state === s_ready)) { // can only kill on first cycle
state <== s_ready; state <== s_ready;
} }

11
rocket/src/main/scala/dpath.scala
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@ -111,8 +111,6 @@ class rocketDpath extends Component
val mem_reg_wdata = Reg() { Bits() }; val mem_reg_wdata = Reg() { Bits() };
val mem_reg_raddr1 = Reg() { UFix() }; val mem_reg_raddr1 = Reg() { UFix() };
val mem_reg_raddr2 = Reg() { UFix() }; val mem_reg_raddr2 = Reg() { UFix() };
val mem_reg_ctrl_mul_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));
val mem_wdata = Wire() { Bits() }; val mem_wdata = Wire() { Bits() };
@ -276,7 +274,7 @@ class rocketDpath extends Component
div.io.dw := ex_reg_ctrl_fn_dw; div.io.dw := ex_reg_ctrl_fn_dw;
div.io.div_fn := ex_reg_ctrl_div_fn; div.io.div_fn := ex_reg_ctrl_div_fn;
div.io.div_val := ex_reg_ctrl_div_val; div.io.div_val := ex_reg_ctrl_div_val;
div.io.div_kill := mem_reg_ctrl_div_val && io.ctrl.killm; div.io.div_kill := io.ctrl.killm;
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;
@ -287,7 +285,7 @@ class rocketDpath extends Component
// multiplier // multiplier
mul.io.mul_val := ex_reg_ctrl_mul_val; mul.io.mul_val := ex_reg_ctrl_mul_val;
mul.io.mul_kill:= mem_reg_ctrl_mul_val && io.ctrl.killm; mul.io.mul_kill:= io.ctrl.killm;
mul.io.dw := ex_reg_ctrl_fn_dw; mul.io.dw := ex_reg_ctrl_fn_dw;
mul.io.mul_fn := ex_reg_ctrl_mul_fn; mul.io.mul_fn := ex_reg_ctrl_mul_fn;
mul.io.mul_tag := ex_reg_waddr; mul.io.mul_tag := ex_reg_waddr;
@ -354,8 +352,6 @@ class rocketDpath extends Component
mem_reg_wdata <== ex_wdata; mem_reg_wdata <== ex_wdata;
mem_reg_raddr1 <== ex_reg_raddr1 mem_reg_raddr1 <== ex_reg_raddr1
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_div_val <== ex_reg_ctrl_div_val;
when (io.ctrl.killx) { when (io.ctrl.killx) {
mem_reg_valid <== Bool(false); mem_reg_valid <== Bool(false);
@ -392,8 +388,7 @@ class rocketDpath extends Component
val mem_ll_wdata = Mux(div_result_val, div_result, val mem_ll_wdata = Mux(div_result_val, div_result,
Mux(mul_result_val, mul_result, Mux(mul_result_val, mul_result,
mem_reg_wdata)) mem_reg_wdata))
val mem_ll_wb = mem_ll_waddr != UFix(0) && val mem_ll_wb = dmem_resp_replay || div_result_val || mul_result_val
(dmem_resp_replay || div_result_val || mul_result_val)
wb_reg_pc <== mem_reg_pc; wb_reg_pc <== mem_reg_pc;
wb_reg_inst <== mem_reg_inst wb_reg_inst <== mem_reg_inst

2
rocket/src/main/scala/multiplier.scala
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@ -62,7 +62,7 @@ class rocketMultiplier extends Component {
r_prod<== rhs_in r_prod<== rhs_in
r_lsb <== Bool(false) r_lsb <== Bool(false)
} }
when (io.result_val && io.result_rdy || io.mul_kill) { when (io.result_val && io.result_rdy || io.mul_kill && r_cnt === UFix(0)) { // can only kill on first cycle
r_val <== Bool(false) r_val <== Bool(false)
} }