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Speed up OptMergePass by 1.7x.

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The main speedup comes from swithing from using a SHA1 hash to std::hash<std::string>. There is no need to use an expensive cryptographic hash for fingerprinting in this context.
This commit is contained in:
Rasmus Munk Larsen 2023-10-02 15:57:18 -07:00
parent 7aa26b3a0b
commit bce984fa60
3 changed files with 15 additions and 12 deletions
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11
passes/opt/opt_merge.cc
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@ -41,7 +41,7 @@ struct OptMergeWorker
CellTypes ct;
int total_count;
SHA1 checksum;
using FingerPrint = std::hash<std::string>::result_type;
static void sort_pmux_conn(dict<RTLIL::IdString, RTLIL::SigSpec> &conn)
{
@ -78,7 +78,7 @@ struct OptMergeWorker
return str;
}
std::string hash_cell_parameters_and_connections(const RTLIL::Cell *cell)
FingerPrint hash_cell_parameters_and_connections(const RTLIL::Cell *cell)
{
vector<string> hash_conn_strings;
std::string hash_string = cell->type.str() + "\n";
@ -149,8 +149,7 @@ struct OptMergeWorker
for (auto it : hash_conn_strings)
hash_string += it;
checksum.update(hash_string);
return checksum.final();
return std::hash<std::string>{}(hash_string);
}
bool compare_cell_parameters_and_connections(const RTLIL::Cell *cell1, const RTLIL::Cell *cell2)
@ -268,13 +267,13 @@ struct OptMergeWorker
}
did_something = false;
dict<std::string, RTLIL::Cell*> sharemap;
std::unordered_map<FingerPrint, RTLIL::Cell*> sharemap;
for (auto cell : cells)
{
if ((!mode_share_all && !ct.cell_known(cell->type)) || !cell->known())
continue;
auto hash = hash_cell_parameters_and_connections(cell);
FingerPrint hash = hash_cell_parameters_and_connections(cell);
auto r = sharemap.insert(std::make_pair(hash, cell));
if (!r.second) {
if (compare_cell_parameters_and_connections(cell, r.first->second)) {