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Add effort limit.

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This commit is contained in:
nella 2026-06-18 11:58:01 +02:00
parent 75a30a22d6
commit 46cbeab720
1 changed files with 27 additions and 12 deletions
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39
passes/opt/opt_dff.cc
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@ -50,9 +50,15 @@ struct BitSim {
ModWalker &modwalker;
dict<SigBit, uint64_t> sim_vals;
uint64_t rng_state;
int max_depth;
int evals_left;
BitSim(Module *m, SigMap &sm, ModWalker &mw)
: module(m), sigmap(sm), modwalker(mw), rng_state(1337) {}
: module(m), sigmap(sm), modwalker(mw), rng_state(1337)
{
max_depth = module->design->scratchpad_get_int("opt_dff.sim_depth", 10000);
evals_left = module->design->scratchpad_get_int("opt_dff.sim_evals", 1000000);
}
uint64_t next_rand() {
uint32_t lo = mkhash_xorshift((uint32_t)rng_state);
@ -61,7 +67,7 @@ struct BitSim {
return rng_state;
}
uint64_t eval_bit(SigBit b) {
uint64_t eval_bit(SigBit b, int depth = 0) {
SigBit mapped = sigmap(b);
if (mapped == State::S0) return 0ULL;
if (mapped == State::S1) return ~0ULL;
@ -69,6 +75,15 @@ struct BitSim {
auto it = sim_vals.find(mapped);
if (it != sim_vals.end()) return it->second;
// Failsafe for huge designs
if (depth >= max_depth || evals_left <= 0) {
uint64_t r = next_rand();
sim_vals[mapped] = r;
return r;
}
evals_left--;
sim_vals[mapped] = 0;
uint64_t res = 0;
@ -85,22 +100,22 @@ struct BitSim {
if (cell->is_builtin_ff()) {
res = next_rand();
} else if (cell->type == ID($_AND_)) {
res = eval_bit(cell->getPort(ID::A)[0]) & eval_bit(cell->getPort(ID::B)[0]);
res = eval_bit(cell->getPort(ID::A)[0], depth+1) & eval_bit(cell->getPort(ID::B)[0], depth+1);
} else if (cell->type == ID($_OR_)) {
res = eval_bit(cell->getPort(ID::A)[0]) | eval_bit(cell->getPort(ID::B)[0]);
res = eval_bit(cell->getPort(ID::A)[0], depth+1) | eval_bit(cell->getPort(ID::B)[0], depth+1);
} else if (cell->type == ID($_XOR_)) {
res = eval_bit(cell->getPort(ID::A)[0]) ^ eval_bit(cell->getPort(ID::B)[0]);
res = eval_bit(cell->getPort(ID::A)[0], depth+1) ^ eval_bit(cell->getPort(ID::B)[0], depth+1);
} else if (cell->type == ID($_NOT_)) {
res = ~eval_bit(cell->getPort(ID::A)[0]);
res = ~eval_bit(cell->getPort(ID::A)[0], depth+1);
} else if (cell->type == ID($_MUX_)) {
uint64_t s = eval_bit(cell->getPort(ID::S)[0]);
uint64_t a = eval_bit(cell->getPort(ID::A)[0]);
uint64_t b = eval_bit(cell->getPort(ID::B)[0]);
uint64_t s = eval_bit(cell->getPort(ID::S)[0], depth+1);
uint64_t a = eval_bit(cell->getPort(ID::A)[0], depth+1);
uint64_t b = eval_bit(cell->getPort(ID::B)[0], depth+1);
res = (a & ~s) | (b & s);
} else if (cell->type == ID($mux)) {
uint64_t s = eval_bit(cell->getPort(ID::S)[0]);
uint64_t a = eval_bit(cell->getPort(ID::A)[driver.offset]);
uint64_t b = eval_bit(cell->getPort(ID::B)[driver.offset]);
uint64_t s = eval_bit(cell->getPort(ID::S)[0], depth+1);
uint64_t a = eval_bit(cell->getPort(ID::A)[driver.offset], depth+1);
uint64_t b = eval_bit(cell->getPort(ID::B)[driver.offset], depth+1);
res = (a & ~s) | (b & s);
} else {
res = next_rand();