riscv/rocket-chip
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added once cycle latency store pipelined d$

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This commit is contained in:
Rimas Avizienis 2011-10-31 15:37:37 -07:00
parent c06e2d16e4
commit 172e561a78
1 changed files with 207 additions and 1 deletions
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208
rocket/src/main/scala/dcache.scala
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@ -40,7 +40,8 @@ class ioDCacheDM extends Bundle() {
// state machine to flush (write back dirty lines, invalidate clean ones) the D$
class rocketDCacheDM_flush(lines: Int, addrbits: Int) extends Component {
val io = new ioDCacheDM();
val dcache = new rocketDCacheDM(lines, addrbits);
// val dcache = new rocketDCacheDM(lines, addrbits);
val dcache = new rocketDCacheDM_1C(lines, addrbits);
val indexbits = ceil(log10(lines)/log10(2)).toInt;
val offsetbits = 6;
@ -248,4 +249,209 @@ class rocketDCacheDM(lines: Int, addrbits: Int) extends Component {
}
}
class rocketDCacheDM_1C(lines: Int, addrbits: Int) extends Component {
val io = new ioDCacheDM();
val indexbits = ceil(log10(lines)/log10(2)).toInt;
val offsetbits = 6;
val tagmsb = addrbits - 1;
val taglsb = indexbits+offsetbits;
val indexmsb = taglsb-1;
val indexlsb = offsetbits;
val offsetmsb = indexlsb-1;
val offsetlsb = 3;
val s_reset :: s_ready :: s_replay_load :: s_start_writeback :: s_writeback :: s_req_refill :: s_refill :: s_resolve_miss :: Nil = Enum(8) { UFix() };
val state = Reg(resetVal = s_reset);
val r_cpu_req_addr = Reg(resetVal = Bits(0, addrbits));
val r_cpu_req_val = Reg(resetVal = Bool(false));
// val r_cpu_req_data = Reg(resetVal = Bits(0,64));
val r_cpu_req_op = Reg(resetVal = Bits(0,4));
// val r_cpu_req_wmask = Reg(resetVal = Bits(0,8));
val r_cpu_req_tag = Reg(resetVal = Bits(0,12));
val p_store_data = Reg(resetVal = Bits(0,64));
val p_store_addr = Reg(resetVal = Bits(0,64));
val p_store_wmask = Reg(resetVal = Bits(0,64));
val p_store_valid = Reg(resetVal = Bool(false));
val req_load = (r_cpu_req_op === M_XRD);
val req_store = (r_cpu_req_op === M_XWR);
val req_flush = (r_cpu_req_op === M_FLA);
when (io.cpu.req_val && io.cpu.req_rdy) {
r_cpu_req_addr <== io.cpu.req_addr;
// r_cpu_req_data <== io.cpu.req_data;
r_cpu_req_op <== io.cpu.req_op;
// r_cpu_req_wmask <== io.cpu.req_wmask;
r_cpu_req_tag <== io.cpu.req_tag;
}
when (io.cpu.req_val && io.cpu.req_rdy && (io.cpu.req_op === M_XWR)) {
p_store_data <== io.cpu.req_data;
p_store_addr <== io.cpu.req_addr;
p_store_wmask <== io.cpu.req_wmask;
p_store_valid <== Bool(true);
}
when (io.cpu.req_rdy) {
r_cpu_req_val <== io.cpu.req_val;
}
when ((state === s_resolve_miss) && !req_load) {
r_cpu_req_val <== Bool(false);
}
// counter
val rr_count = Reg(resetVal = UFix(0,2));
val rr_count_next = rr_count + UFix(1);
when (((state === s_refill) && io.mem.resp_val) || ((state === s_writeback) && io.mem.req_rdy)) {
rr_count <== rr_count_next;
}
// tag array
val tag_we = (state === s_resolve_miss);
val tag_waddr = r_cpu_req_addr(indexmsb, indexlsb).toUFix;
val tag_wdata = r_cpu_req_addr(tagmsb, taglsb);
val tag_array = Mem(lines, tag_we, tag_waddr, tag_wdata);
val tag_raddr =
Mux((state === s_ready), io.cpu.req_addr(indexmsb, indexlsb).toUFix,
r_cpu_req_addr(indexmsb, indexlsb).toUFix);
val tag_rdata = Reg(tag_array.read(tag_raddr));
// valid bit array
val vb_array = Reg(resetVal = Bits(0, lines));
val vb_rdata = Reg(vb_array(tag_raddr));
when (tag_we && !req_flush) {
vb_array <== vb_array.bitSet(r_cpu_req_addr(indexmsb, indexlsb).toUFix, UFix(1,1));
}
when (tag_we && req_flush) {
vb_array <== vb_array.bitSet(r_cpu_req_addr(indexmsb, indexlsb).toUFix, UFix(0,1));
}
val tag_valid = vb_rdata.toBool;
val tag_match = tag_valid && !req_flush && (tag_rdata === r_cpu_req_addr(tagmsb, taglsb));
val ldst_conflict = io.cpu.req_val && (io.cpu.req_op === M_XRD) && (io.cpu.req_addr === p_store_addr);
val store = ((state === s_ready) && p_store_valid && (!io.cpu.req_val || ldst_conflict || io.cpu.req_op === M_XWR)) ||
((state === s_resolve_miss) && req_store);
// dirty bit array
val db_array = Reg(resetVal = Bits(0, lines));
val db_rdata = Reg(db_array(tag_raddr));
val tag_dirty = db_rdata.toBool;
when (store) {
p_store_valid <== Bool(false);
db_array <== db_array.bitSet(p_store_addr(indexmsb, indexlsb).toUFix, UFix(1,1));
}
when (tag_we) {
db_array <== db_array.bitSet(r_cpu_req_addr(indexmsb, indexlsb).toUFix, UFix(0,1));
}
// data array
val data_array_we = ((state === s_refill) && io.mem.resp_val) || store;
val data_array_waddr =
Mux((state === s_refill), Cat(r_cpu_req_addr(indexmsb, indexlsb), rr_count).toUFix,
p_store_addr(indexmsb, offsetmsb-1).toUFix);
val data_array_wdata =
Mux((state === s_refill), io.mem.resp_data,
Cat(p_store_data, p_store_data));
val p_wmask_expand =
Cat(Fill(8, p_store_wmask(7)),
Fill(8, p_store_wmask(6)),
Fill(8, p_store_wmask(5)),
Fill(8, p_store_wmask(4)),
Fill(8, p_store_wmask(3)),
Fill(8, p_store_wmask(2)),
Fill(8, p_store_wmask(1)),
Fill(8, p_store_wmask(0)));
val store_wmask =
Mux(p_store_addr(offsetlsb).toBool,
Cat(p_wmask_expand, Bits(0,64)),
Cat(Bits(0,64), p_wmask_expand));
val data_array_wmask =
Mux((state === s_refill), ~Bits(0,128),
store_wmask);
val data_array = Mem(lines*4, data_array_we, data_array_waddr, data_array_wdata, wrMask = data_array_wmask, resetVal = null);
val data_array_raddr =
Mux((state === s_writeback) && io.mem.req_rdy, Cat(r_cpu_req_addr(indexmsb, indexlsb), rr_count_next).toUFix,
Mux((state === s_start_writeback) || (state === s_writeback), Cat(r_cpu_req_addr(indexmsb, indexlsb), rr_count).toUFix,
Mux((state === s_resolve_miss), r_cpu_req_addr(indexmsb, offsetmsb-1),
io.cpu.req_addr(indexmsb, offsetmsb-1))));
val data_array_rdata = Reg(data_array.read(data_array_raddr));
// output signals
// io.cpu.req_rdy := (state === s_ready) && (!r_cpu_req_val || (tag_match && req_load && !(p_store_valid && (r_cpu_req_addr === p_store_addr))));
io.cpu.req_rdy := (state === s_ready) && (!r_cpu_req_val || tag_match) && !(p_store_valid && ldst_conflict);
io.cpu.resp_val := ((state === s_ready) && r_cpu_req_val && tag_match && req_load) ||
((state === s_resolve_miss) && req_flush);
io.cpu.resp_tag := r_cpu_req_tag;
io.cpu.resp_data :=
Mux(r_cpu_req_addr(offsetlsb).toBool, data_array_rdata(127, 64),
data_array_rdata(63,0));
io.mem.req_val := (state === s_req_refill) || (state === s_writeback);
io.mem.req_rw := (state === s_writeback);
io.mem.req_wdata := data_array_rdata;
io.mem.req_tag := UFix(0);
io.mem.req_addr :=
Mux(state === s_writeback, Cat(tag_rdata, r_cpu_req_addr(indexmsb, indexlsb), rr_count).toUFix,
Cat(r_cpu_req_addr(tagmsb, indexlsb), Bits(0,2)).toUFix);
// control state machine
switch (state) {
is (s_reset) {
state <== s_ready;
}
is (s_ready) {
when (p_store_valid && ldst_conflict) {
state <== s_replay_load;
}
when (!r_cpu_req_val || tag_match) {
state <== s_ready;
}
when (tag_valid & tag_dirty) {
state <== s_start_writeback;
}
when (req_flush) {
state <== s_resolve_miss;
}
otherwise {
state <== s_req_refill;
}
}
is (s_replay_load) {
state <== s_ready;
}
is (s_start_writeback) {
state <== s_writeback;
}
is (s_writeback) {
when (io.mem.req_rdy && (rr_count === UFix(3,2))) {
when (req_flush) { state <== s_resolve_miss; }
otherwise { state <== s_req_refill; }
}
}
is (s_req_refill)
{
when (io.mem.req_rdy) { state <== s_refill; }
}
is (s_refill) {
when (io.mem.resp_val && (rr_count === UFix(3,2))) { state <== s_resolve_miss; }
}
is (s_resolve_miss) {
state <== s_ready;
}
}
}
}