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dff2dffe: Add option for unmap to only remove DFFE with low CE signal use 

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
This commit is contained in:
Sylvain Munaut 2018-11-15 02:48:44 +01:00
parent ab97eddee9
commit 8d3ab626ea
1 changed files with 36 additions and 1 deletions
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37
passes/techmap/dff2dffe.cc
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@ -263,10 +263,14 @@ struct Dff2dffePass : public Pass {
log("more feedback paths to $dffe cells. It also works on gate-level cells such as\n");
log("$_DFF_P_, $_DFF_N_ and $_MUX_.\n");
log("\n");
log(" -unmap\n");
log(" -unmap");
log(" operate in the opposite direction: replace $dffe cells with combinations\n");
log(" of $dff and $mux cells. the options below are ignore in unmap mode.\n");
log("\n");
log(" -unmap-mince N\n");
log(" Same as -unmap but only unmap $dffe where the clock enable port\n");
log(" signal is used by less $dffe than the specified number\n");
log("\n");
log(" -direct <internal_gate_type> <external_gate_type>\n");
log(" map directly to external gate type. <internal_gate_type> can\n");
log(" be any internal gate-level FF cell (except $_DFFE_??_). the\n");
@ -289,6 +293,7 @@ struct Dff2dffePass : public Pass {
log_header(design, "Executing DFF2DFFE pass (transform $dff to $dffe where applicable).\n");
bool unmap_mode = false;
int min_ce_use = -1;
dict<IdString, IdString> direct_dict;
size_t argidx;
@ -297,6 +302,11 @@ struct Dff2dffePass : public Pass {
unmap_mode = true;
continue;
}
if (args[argidx] == "-unmap-mince" && argidx + 1 < args.size()) {
unmap_mode = true;
min_ce_use = std::stoi(args[++argidx]);
continue;
}
if (args[argidx] == "-direct" && argidx + 2 < args.size()) {
string direct_from = RTLIL::escape_id(args[++argidx]);
string direct_to = RTLIL::escape_id(args[++argidx]);
@ -343,8 +353,21 @@ struct Dff2dffePass : public Pass {
if (!mod->has_processes_warn())
{
if (unmap_mode) {
SigMap sigmap(mod);
for (auto cell : mod->selected_cells()) {
if (cell->type == "$dffe") {
if (min_ce_use >= 0) {
int ce_use = 0;
for (auto cell_other : mod->selected_cells()) {
if (cell_other->type != cell->type)
continue;
if (sigmap(cell->getPort("\\EN")) == sigmap(cell_other->getPort("\\EN")))
ce_use++;
}
if (ce_use >= min_ce_use)
continue;
}
RTLIL::SigSpec tmp = mod->addWire(NEW_ID, GetSize(cell->getPort("\\D")));
mod->addDff(NEW_ID, cell->getPort("\\CLK"), tmp, cell->getPort("\\Q"), cell->getParam("\\CLK_POLARITY").as_bool());
if (cell->getParam("\\EN_POLARITY").as_bool())
@ -355,6 +378,18 @@ struct Dff2dffePass : public Pass {
continue;
}
if (cell->type.substr(0, 7) == "$_DFFE_") {
if (min_ce_use >= 0) {
int ce_use = 0;
for (auto cell_other : mod->selected_cells()) {
if (cell_other->type != cell->type)
continue;
if (sigmap(cell->getPort("\\E")) == sigmap(cell_other->getPort("\\E")))
ce_use++;
}
if (ce_use >= min_ce_use)
continue;
}
bool clk_pol = cell->type.substr(7, 1) == "P";
bool en_pol = cell->type.substr(8, 1) == "P";
RTLIL::SigSpec tmp = mod->addWire(NEW_ID);