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Merged
akashlevy merged 3 commits into from
May 26, 2026
Merged

opt -max_iter #166

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9a22502
opt -max_iter
akashlevy May 26, 2026
9ded747
Update passes/opt/opt.cc
akashlevy May 26, 2026
faec5b5
Smallfix
akashlevy May 26, 2026
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2 changes: 1 addition & 1 deletion docs/source/code_examples/macro_commands/opt.ys
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Original file line number Diff line number Diff line change
Expand Up @@ -13,4 +13,4 @@ do
opt_boundary (-boundary only)
opt_clean
opt_expr
while <changed design>
while <changed design in opt_dff> (up to -max_iter iterations)
29 changes: 26 additions & 3 deletions passes/opt/opt.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -50,7 +50,7 @@ struct OptPass : public Pass {
log(" opt_boundary (-boundary only)\n");
log(" opt_clean [-purge]\n");
log(" opt_expr [-mux_undef] [-mux_bool] [-undriven] [-noclkinv] [-fine] [-full] [-keepdc]\n");
log(" while <changed design>\n");
log(" while <changed design> (up to -max_iter iterations)\n");
log("\n");
log("When called with -fast the following script is used instead:\n");
log("\n");
Expand All @@ -61,11 +61,14 @@ struct OptPass : public Pass {
log(" opt_hier (-hier only)\n");
log(" opt_boundary (-boundary only)\n");
log(" opt_clean [-purge]\n");
log(" while <changed design in opt_dff>\n");
log(" while <changed design in opt_dff> (up to -max_iter iterations)\n");
log("\n");
log("Note: Options in square brackets (such as [-keepdc]) are passed through to\n");
log("the opt_* commands when given to 'opt'.\n");
log("\n");
log(" -max_iter <number>\n");
log(" only run the specified number of iterations.\n");
log(" default: 20. use 0 for unlimited.\n");
log("\n");
}
void execute(std::vector<std::string> args, RTLIL::Design *design) override
Expand All @@ -80,6 +83,8 @@ struct OptPass : public Pass {
bool noff_mode = false;
bool hier_mode = false;
bool boundary_mode = false;
int max_iter = 20;
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bool reached_max_iter = false;

log_header(design, "Executing OPT pass (performing simple optimizations).\n");
log_push();
Expand Down Expand Up @@ -155,13 +160,19 @@ struct OptPass : public Pass {
boundary_mode = true;
continue;
}
if (args[argidx] == "-max_iter" && argidx+1 < args.size()) {
max_iter = atoi(args[++argidx].c_str());
continue;
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}
break;
}
extra_args(args, argidx, design);

if (fast_mode)
{
int iter = 0;
while (1) {
iter++;
Pass::call(design, "opt_expr" + opt_expr_args);
Pass::call(design, "opt_merge" + opt_merge_args);
design->scratchpad_unset("opt.did_something");
Expand All @@ -174,6 +185,10 @@ struct OptPass : public Pass {
if (boundary_mode)
Pass::call(design, "opt_boundary");
Pass::call(design, "opt_clean" + opt_clean_args);
if (max_iter > 0 && iter >= max_iter) {
reached_max_iter = true;
break;
}
log_header(design, "Rerunning OPT passes. (Removed registers in this run.)\n");
}
Pass::call(design, "opt_clean" + opt_clean_args);
Expand All @@ -182,7 +197,9 @@ struct OptPass : public Pass {
{
Pass::call(design, "opt_expr" + opt_expr_args);
Pass::call(design, "opt_merge -nomux" + opt_merge_args);
int iter = 0;
while (1) {
iter++;
design->scratchpad_unset("opt.did_something");
Pass::call(design, "opt_muxtree");
Pass::call(design, "opt_reduce" + opt_reduce_args);
Expand All @@ -199,6 +216,10 @@ struct OptPass : public Pass {
Pass::call(design, "opt_expr" + opt_expr_args);
if (design->scratchpad_get_bool("opt.did_something") == false)
break;
if (max_iter > 0 && iter >= max_iter) {
reached_max_iter = true;
break;
}
log_header(design, "Rerunning OPT passes. (Maybe there is more to do..)\n");
}
}
Expand All @@ -207,7 +228,9 @@ struct OptPass : public Pass {
design->sort();
design->check();

log_header(design, "Finished fast OPT passes.%s\n", fast_mode ? "" : " (There is nothing left to do.)");
const char *done_reason = reached_max_iter ? " (Reached maximum number of iterations.)" :
(fast_mode ? "" : " (There is nothing left to do.)");
log_header(design, "Finished %sOPT passes.%s\n", fast_mode ? "fast " : "", done_reason);
log_pop();
}
} OptPass;
Expand Down
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