luke
/
yosys
mirror of https://github.com/YosysHQ/yosys.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

necessary clock gate pass modifications

This commit is contained in:
Stan Lee 2026-06-01 17:19:23 -07:00
parent 483b1536d7
commit 1b707c61f7
1 changed files with 28 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

32
passes/techmap/clockgate.cc
View File

@ -255,6 +255,8 @@ struct ClockgatePass : public Pass {
log(" Intended for DFT scan-enable pins.\n");
log(" -min_net_size <n>\n");
log(" Only transform sets of at least <n> eligible FFs.\n");
log(" -min_ff_size <n>\n");
log(" Only transform FFs whose original (pre-split) register width, or 'ff_width' attribute\n");
log(" -min_disabled_threshold <f>\n");
log(" Only transform sets of FFs where the total sum of disabled FFs is greater than <f>.\n");
log(" -max_src <n>\n");
@ -323,6 +325,8 @@ struct ClockgatePass : public Pass {
std::vector<std::string> liberty_files;
std::vector<std::string> dont_use_cells;
int min_net_size = 0;
int min_ff_size = 0;
bool use_ff_size_threshold = false;
double min_disabled_threshold = -1;
bool use_disabled_threshold = false;
int max_src = -1;
@ -357,6 +361,11 @@ struct ClockgatePass : public Pass {
min_net_size = atoi(args[++argidx].c_str());
continue;
}
if (args[argidx] == "-min_ff_size" && argidx+1 < args.size()) {
min_ff_size = atoi(args[++argidx].c_str());
use_ff_size_threshold = true;
continue;
}
if (args[argidx] == "-min_disabled_threshold" && argidx+1 < args.size()) {
min_disabled_threshold = atof(args[++argidx].c_str());
use_disabled_threshold = true;
@ -411,6 +420,13 @@ struct ClockgatePass : public Pass {
if (!ff.sig_clk[0].is_wire() || !ff.sig_ce[0].is_wire())
continue;
if (use_ff_size_threshold) {
std::string attr = cell->get_string_attribute(ID(ff_width));
int orig_w = attr.empty() ? ff.width : atoi(attr.c_str());
if (orig_w < min_ff_size)
continue;
}
ce_ffs.insert(cell);
ClkNetInfo info = clk_info_from_ff(ff);
@ -441,9 +457,13 @@ struct ClockgatePass : public Pass {
auto& gclk = clk_net.second;
// Check if the clock net qualifies for clock gating.
bool qualifies = use_disabled_threshold
? (gclk.en_disabled_sum >= min_disabled_threshold)
: (gclk.net_size >= min_net_size);
bool qualifies;
if (use_ff_size_threshold)
qualifies = (gclk.net_size >= 1);
else if (use_disabled_threshold)
qualifies = (gclk.en_disabled_sum >= min_disabled_threshold);
else
qualifies = (gclk.net_size >= min_net_size);
if (!qualifies)
continue;
@ -563,7 +583,11 @@ struct ClockgatePass : public Pass {
clk_nets.clear();
}
log("Converted %d FFs using %s.\n", gated_flop_count, use_disabled_threshold ? "disabled threshold" : "net size");
const char *mode = use_ff_size_threshold ? "FF width threshold"
: use_disabled_threshold ? "disabled threshold"
: "net size";
log("Converted %d FFs using %s.\n", gated_flop_count, mode);
}
} ClockgatePass;