Files
yosys/tests/unit/kernel/twineHashTest.cc

91 lines
2.7 KiB
C++

#include <gtest/gtest.h>
#include <chrono>
#include "kernel/rtlil.h"
#include "kernel/yosys.h"
YOSYS_NAMESPACE_BEGIN
namespace {
// A name reached through a suffix chain must hash the same as the identical
// name interned as a single leaf, otherwise TwineSearch misses it.
TEST(TwineHashTest, Fragmentation)
{
TwinePool pool;
DeepTwineHash hash{&pool};
IdString flat = pool.add(std::string("$abcdefghij"));
IdString base = pool.add(std::string("$abcde"));
IdString split = pool.add(TwineSpec::Suffix{base, "fghij"});
EXPECT_EQ(hash(flat.untag()), hash(split.untag()));
EXPECT_EQ(hash(flat.untag()), hash(std::string_view("$abcdefghij")));
}
// The 8-byte buffering must not leak fragment boundaries at any offset.
TEST(TwineHashTest, SplitPoints)
{
const std::string content = "$0123456789abcdefghijklmnopqr";
TwinePool pool;
DeepTwineHash hash{&pool};
const size_t want = hash(std::string_view(content));
for (size_t cut = 1; cut < content.size(); cut++) {
IdString base = pool.add(content.substr(0, cut));
IdString split = pool.add(TwineSpec::Suffix{base, content.substr(cut)});
EXPECT_EQ(hash(split.untag()), want) << "split after " << cut;
}
}
TEST(TwineHashTest, DistinctContent)
{
TwinePool twines;
DeepTwineHash hash{&twines};
std::set<size_t> seen;
for (int i = 0; i < 4096; i++) {
IdString ref = twines.add(stringf("$name%d", i));
seen.insert(hash(ref.untag()));
}
EXPECT_GT(seen.size(), 4000u);
}
// Not an assertion of speed, but a harness: reports how long interning and
// rehashing a large pool takes so the cost of the hashing path is visible.
TEST(TwineHashTest, BenchmarkIntern)
{
constexpr int kNames = 40000;
TwinePool pool;
auto t0 = std::chrono::steady_clock::now();
IdString prefix = pool.add(std::string("$bench"));
std::vector<IdString> refs;
refs.reserve(kNames);
for (int i = 0; i < kNames; i++)
refs.push_back(pool.add(TwineSpec::Suffix{prefix, stringf("$%d", i)}));
auto t1 = std::chrono::steady_clock::now();
TwineSearch search(&pool);
auto t2 = std::chrono::steady_clock::now();
for (int i = 0; i < kNames; i++)
ASSERT_EQ(search.find(pool.str(refs[i])), refs[i]) << "at " << i;
auto t3 = std::chrono::steady_clock::now();
auto ms = [](auto a, auto b) {
return std::chrono::duration_cast<std::chrono::microseconds>(b - a).count() / 1000.0;
};
RecordProperty("intern_ms", std::to_string(ms(t0, t1)));
RecordProperty("search_build_ms", std::to_string(ms(t1, t2)));
RecordProperty("search_find_ms", std::to_string(ms(t2, t3)));
std::cerr << "[ BENCH ] intern " << ms(t0, t1) << " ms, TwineSearch build "
<< ms(t1, t2) << " ms, " << kNames << " finds " << ms(t2, t3) << " ms\n";
}
} // namespace
YOSYS_NAMESPACE_END