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-rw-r--r--passes/techmap/muxcover.cc227
1 files changed, 165 insertions, 62 deletions
diff --git a/passes/techmap/muxcover.cc b/passes/techmap/muxcover.cc
index 12da9ed0..c84cfc39 100644
--- a/passes/techmap/muxcover.cc
+++ b/passes/techmap/muxcover.cc
@@ -23,6 +23,7 @@
USING_YOSYS_NAMESPACE
PRIVATE_NAMESPACE_BEGIN
+#define COST_DMUX 90
#define COST_MUX2 100
#define COST_MUX4 220
#define COST_MUX8 460
@@ -57,6 +58,13 @@ struct MuxcoverWorker
bool use_mux8;
bool use_mux16;
bool nodecode;
+ bool nopartial;
+
+ int cost_dmux;
+ int cost_mux2;
+ int cost_mux4;
+ int cost_mux8;
+ int cost_mux16;
MuxcoverWorker(Module *module) : module(module), sigmap(module)
{
@@ -64,9 +72,32 @@ struct MuxcoverWorker
use_mux8 = false;
use_mux16 = false;
nodecode = false;
+ nopartial = false;
+ cost_dmux = COST_DMUX;
+ cost_mux2 = COST_MUX2;
+ cost_mux4 = COST_MUX4;
+ cost_mux8 = COST_MUX8;
+ cost_mux16 = COST_MUX16;
decode_mux_counter = 0;
}
+ bool xcmp(std::initializer_list<SigBit> list)
+ {
+ auto cursor = list.begin(), end = list.end();
+ log_assert(cursor != end);
+ SigBit tmp = *(cursor++);
+ while (cursor != end) {
+ SigBit bit = *(cursor++);
+ if (bit == State::Sx)
+ continue;
+ if (tmp == State::Sx)
+ tmp = bit;
+ if (bit != tmp)
+ return false;
+ }
+ return true;
+ }
+
void treeify()
{
pool<SigBit> roots;
@@ -124,13 +155,22 @@ struct MuxcoverWorker
log(" Finished treeification: Found %d trees.\n", GetSize(tree_list));
}
- bool follow_muxtree(SigBit &ret_bit, tree_t &tree, SigBit bit, const char *path)
+ bool follow_muxtree(SigBit &ret_bit, tree_t &tree, SigBit bit, const char *path, bool first_layer = true)
{
if (*path) {
- if (tree.muxes.count(bit) == 0)
- return false;
+ if (tree.muxes.count(bit) == 0) {
+ if (first_layer || nopartial)
+ return false;
+ while (path[0] && path[1])
+ path++;
+ if (path[0] == 'S')
+ ret_bit = State::Sx;
+ else
+ ret_bit = bit;
+ return true;
+ }
char port_name[3] = {'\\', *path, 0};
- return follow_muxtree(ret_bit, tree, sigmap(tree.muxes.at(bit)->getPort(port_name)), path+1);
+ return follow_muxtree(ret_bit, tree, sigmap(tree.muxes.at(bit)->getPort(port_name)), path+1, false);
} else {
ret_bit = bit;
return true;
@@ -139,7 +179,7 @@ struct MuxcoverWorker
int prepare_decode_mux(SigBit &A, SigBit B, SigBit sel, SigBit bit)
{
- if (A == B)
+ if (A == B || sel == State::Sx)
return 0;
tuple<SigBit, SigBit, SigBit> key(A, B, sel);
@@ -157,7 +197,10 @@ struct MuxcoverWorker
if (std::get<2>(entry))
return 0;
- return COST_MUX2 / GetSize(std::get<1>(entry));
+ if (A == State::Sx || B == State::Sx)
+ return 0;
+
+ return cost_dmux / GetSize(std::get<1>(entry));
}
void implement_decode_mux(SigBit ctrl_bit)
@@ -174,9 +217,32 @@ struct MuxcoverWorker
implement_decode_mux(std::get<0>(key));
implement_decode_mux(std::get<1>(key));
- module->addMuxGate(NEW_ID, std::get<0>(key), std::get<1>(key), std::get<2>(key), ctrl_bit);
+ if (std::get<0>(key) == State::Sx) {
+ module->addBufGate(NEW_ID, std::get<1>(key), ctrl_bit);
+ } else if (std::get<1>(key) == State::Sx) {
+ module->addBufGate(NEW_ID, std::get<0>(key), ctrl_bit);
+ } else {
+ module->addMuxGate(NEW_ID, std::get<0>(key), std::get<1>(key), std::get<2>(key), ctrl_bit);
+ decode_mux_counter++;
+ }
std::get<2>(entry) = true;
- decode_mux_counter++;
+ }
+
+ void find_best_covers(tree_t &tree, const vector<SigBit> &bits)
+ {
+ for (auto bit : bits)
+ find_best_cover(tree, bit);
+ }
+
+ int sum_best_covers(tree_t &tree, const vector<SigBit> &bits)
+ {
+ int sum = 0;
+ for (auto bit : pool<SigBit>(bits.begin(), bits.end())) {
+ int cost = tree.newmuxes.at(bit).cost;
+ log_debug(" Best cost for %s: %d\n", log_signal(bit), cost);
+ sum += cost;
+ }
+ return sum;
}
int find_best_cover(tree_t &tree, SigBit bit)
@@ -209,9 +275,13 @@ struct MuxcoverWorker
mux.inputs.push_back(B);
mux.selects.push_back(S1);
- mux.cost += COST_MUX2;
- mux.cost += find_best_cover(tree, A);
- mux.cost += find_best_cover(tree, B);
+ find_best_covers(tree, mux.inputs);
+ log_debug(" Decode cost for mux2 at %s: %d\n", log_signal(bit), mux.cost);
+
+ mux.cost += cost_mux2;
+ mux.cost += sum_best_covers(tree, mux.inputs);
+
+ log_debug(" Cost of mux2 at %s: %d\n", log_signal(bit), mux.cost);
best_mux = mux;
}
@@ -229,7 +299,7 @@ struct MuxcoverWorker
ok = ok && follow_muxtree(S2, tree, bit, "BS");
if (nodecode)
- ok = ok && S1 == S2;
+ ok = ok && xcmp({S1, S2});
ok = ok && follow_muxtree(T1, tree, bit, "S");
@@ -247,13 +317,15 @@ struct MuxcoverWorker
mux.selects.push_back(S1);
mux.selects.push_back(T1);
- mux.cost += COST_MUX4;
- mux.cost += find_best_cover(tree, A);
- mux.cost += find_best_cover(tree, B);
- mux.cost += find_best_cover(tree, C);
- mux.cost += find_best_cover(tree, D);
+ find_best_covers(tree, mux.inputs);
+ log_debug(" Decode cost for mux4 at %s: %d\n", log_signal(bit), mux.cost);
+
+ mux.cost += cost_mux4;
+ mux.cost += sum_best_covers(tree, mux.inputs);
+
+ log_debug(" Cost of mux4 at %s: %d\n", log_signal(bit), mux.cost);
- if (best_mux.cost > mux.cost)
+ if (best_mux.cost >= mux.cost)
best_mux = mux;
}
}
@@ -277,13 +349,13 @@ struct MuxcoverWorker
ok = ok && follow_muxtree(S4, tree, bit, "BBS");
if (nodecode)
- ok = ok && S1 == S2 && S2 == S3 && S3 == S4;
+ ok = ok && xcmp({S1, S2, S3, S4});
ok = ok && follow_muxtree(T1, tree, bit, "AS");
ok = ok && follow_muxtree(T2, tree, bit, "BS");
if (nodecode)
- ok = ok && T1 == T2;
+ ok = ok && xcmp({T1, T2});
ok = ok && follow_muxtree(U1, tree, bit, "S");
@@ -310,17 +382,15 @@ struct MuxcoverWorker
mux.selects.push_back(T1);
mux.selects.push_back(U1);
- mux.cost += COST_MUX8;
- mux.cost += find_best_cover(tree, A);
- mux.cost += find_best_cover(tree, B);
- mux.cost += find_best_cover(tree, C);
- mux.cost += find_best_cover(tree, D);
- mux.cost += find_best_cover(tree, E);
- mux.cost += find_best_cover(tree, F);
- mux.cost += find_best_cover(tree, G);
- mux.cost += find_best_cover(tree, H);
-
- if (best_mux.cost > mux.cost)
+ find_best_covers(tree, mux.inputs);
+ log_debug(" Decode cost for mux8 at %s: %d\n", log_signal(bit), mux.cost);
+
+ mux.cost += cost_mux8;
+ mux.cost += sum_best_covers(tree, mux.inputs);
+
+ log_debug(" Cost of mux8 at %s: %d\n", log_signal(bit), mux.cost);
+
+ if (best_mux.cost >= mux.cost)
best_mux = mux;
}
}
@@ -356,7 +426,7 @@ struct MuxcoverWorker
ok = ok && follow_muxtree(S8, tree, bit, "BBBS");
if (nodecode)
- ok = ok && S1 == S2 && S2 == S3 && S3 == S4 && S4 == S5 && S5 == S6 && S6 == S7 && S7 == S8;
+ ok = ok && xcmp({S1, S2, S3, S4, S5, S6, S7, S8});
ok = ok && follow_muxtree(T1, tree, bit, "AAS");
ok = ok && follow_muxtree(T2, tree, bit, "ABS");
@@ -364,13 +434,13 @@ struct MuxcoverWorker
ok = ok && follow_muxtree(T4, tree, bit, "BBS");
if (nodecode)
- ok = ok && T1 == T2 && T2 == T3 && T3 == T4;
+ ok = ok && xcmp({T1, T2, T3, T4});
ok = ok && follow_muxtree(U1, tree, bit, "AS");
ok = ok && follow_muxtree(U2, tree, bit, "BS");
if (nodecode)
- ok = ok && U1 == U2;
+ ok = ok && xcmp({U1, U2});
ok = ok && follow_muxtree(V1, tree, bit, "S");
@@ -414,25 +484,15 @@ struct MuxcoverWorker
mux.selects.push_back(U1);
mux.selects.push_back(V1);
- mux.cost += COST_MUX16;
- mux.cost += find_best_cover(tree, A);
- mux.cost += find_best_cover(tree, B);
- mux.cost += find_best_cover(tree, C);
- mux.cost += find_best_cover(tree, D);
- mux.cost += find_best_cover(tree, E);
- mux.cost += find_best_cover(tree, F);
- mux.cost += find_best_cover(tree, G);
- mux.cost += find_best_cover(tree, H);
- mux.cost += find_best_cover(tree, I);
- mux.cost += find_best_cover(tree, J);
- mux.cost += find_best_cover(tree, K);
- mux.cost += find_best_cover(tree, L);
- mux.cost += find_best_cover(tree, M);
- mux.cost += find_best_cover(tree, N);
- mux.cost += find_best_cover(tree, O);
- mux.cost += find_best_cover(tree, P);
-
- if (best_mux.cost > mux.cost)
+ find_best_covers(tree, mux.inputs);
+ log_debug(" Decode cost for mux16 at %s: %d\n", log_signal(bit), mux.cost);
+
+ mux.cost += cost_mux16;
+ mux.cost += sum_best_covers(tree, mux.inputs);
+
+ log_debug(" Cost of mux16 at %s: %d\n", log_signal(bit), mux.cost);
+
+ if (best_mux.cost >= mux.cost)
best_mux = mux;
}
}
@@ -528,6 +588,7 @@ struct MuxcoverWorker
void treecover(tree_t &tree)
{
int count_muxes_by_type[4] = {0, 0, 0, 0};
+ log_debug(" Searching for best cover for tree at %s.\n", log_signal(tree.root));
find_best_cover(tree, tree.root);
implement_best_cover(tree, tree.root, count_muxes_by_type);
log(" Replaced tree at %s: %d MUX2, %d MUX4, %d MUX8, %d MUX16\n", log_signal(tree.root),
@@ -544,12 +605,13 @@ struct MuxcoverWorker
log(" Covering trees:\n");
- // pre-fill cache of decoder muxes
- if (!nodecode)
+ if (!nodecode) {
+ log_debug(" Populating cache of decoder muxes.\n");
for (auto &tree : tree_list) {
find_best_cover(tree, tree.root);
tree.newmuxes.clear();
}
+ }
for (auto &tree : tree_list)
treecover(tree);
@@ -569,15 +631,25 @@ struct MuxcoverPass : public Pass {
log("\n");
log("Cover trees of $_MUX_ cells with $_MUX{4,8,16}_ cells\n");
log("\n");
- log(" -mux4, -mux8, -mux16\n");
- log(" Use the specified types of MUXes. If none of those options are used,\n");
- log(" the effect is the same as if all of them where used.\n");
+ log(" -mux4[=cost], -mux8[=cost], -mux16[=cost]\n");
+ log(" Use the specified types of MUXes (with optional integer costs). If none\n");
+ log(" of these options are given, the effect is the same as if all of them are.\n");
+ log(" Default costs: $_MUX_ = %d, $_MUX4_ = %d,\n", COST_MUX2, COST_MUX4);
+ log(" $_MUX8_ = %d, $_MUX16_ = %d\n", COST_MUX8, COST_MUX16);
+ log("\n");
+ log(" -dmux=cost\n");
+ log(" Use the specified cost for $_MUX_ cells used in decoders.\n");
+ log(" Default cost: %d\n", COST_DMUX);
log("\n");
log(" -nodecode\n");
log(" Do not insert decoder logic. This reduces the number of possible\n");
log(" substitutions, but guarantees that the resulting circuit is not\n");
log(" less efficient than the original circuit.\n");
log("\n");
+ log(" -nopartial\n");
+ log(" Do not consider mappings that use $_MUX<N>_ to select from less\n");
+ log(" than <N> different signals.\n");
+ log("\n");
}
void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
{
@@ -587,26 +659,52 @@ struct MuxcoverPass : public Pass {
bool use_mux8 = false;
bool use_mux16 = false;
bool nodecode = false;
+ bool nopartial = false;
+ int cost_dmux = COST_DMUX;
+ int cost_mux4 = COST_MUX4;
+ int cost_mux8 = COST_MUX8;
+ int cost_mux16 = COST_MUX16;
size_t argidx;
for (argidx = 1; argidx < args.size(); argidx++)
{
- if (args[argidx] == "-mux4") {
+ const auto &arg = args[argidx];
+ if (arg.size() >= 5 && arg.substr(0,5) == "-mux4") {
use_mux4 = true;
+ if (arg.size() > 5) {
+ if (arg[5] != '=') break;
+ cost_mux4 = atoi(arg.substr(6).c_str());
+ }
continue;
}
- if (args[argidx] == "-mux8") {
+ if (arg.size() >= 5 && arg.substr(0,5) == "-mux8") {
use_mux8 = true;
+ if (arg.size() > 5) {
+ if (arg[5] != '=') break;
+ cost_mux8 = atoi(arg.substr(6).c_str());
+ }
continue;
}
- if (args[argidx] == "-mux16") {
+ if (arg.size() >= 6 && arg.substr(0,6) == "-mux16") {
use_mux16 = true;
+ if (arg.size() > 6) {
+ if (arg[6] != '=') break;
+ cost_mux16 = atoi(arg.substr(7).c_str());
+ }
+ continue;
+ }
+ if (arg.size() >= 6 && arg.substr(0,6) == "-dmux=") {
+ cost_dmux = atoi(arg.substr(6).c_str());
continue;
}
- if (args[argidx] == "-nodecode") {
+ if (arg == "-nodecode") {
nodecode = true;
continue;
}
+ if (arg == "-nopartial") {
+ nopartial = true;
+ continue;
+ }
break;
}
extra_args(args, argidx, design);
@@ -623,7 +721,12 @@ struct MuxcoverPass : public Pass {
worker.use_mux4 = use_mux4;
worker.use_mux8 = use_mux8;
worker.use_mux16 = use_mux16;
+ worker.cost_dmux = cost_dmux;
+ worker.cost_mux4 = cost_mux4;
+ worker.cost_mux8 = cost_mux8;
+ worker.cost_mux16 = cost_mux16;
worker.nodecode = nodecode;
+ worker.nopartial = nopartial;
worker.run();
}
}
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