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new f49284036e [Enhancement] Refactor functions in int_exp by templates
(#9939)
f49284036e is described below
commit f49284036e1ed2bb5597cd6472720552a9c19054
Author: Twice <[email protected]>
AuthorDate: Sat Jun 4 11:53:31 2022 +0800
[Enhancement] Refactor functions in int_exp by templates (#9939)
---
be/src/vec/common/int_exp.h | 122 ++++++++++++--------------------------------
1 file changed, 34 insertions(+), 88 deletions(-)
diff --git a/be/src/vec/common/int_exp.h b/be/src/vec/common/int_exp.h
index 440366ac16..b3ebc20eea 100644
--- a/be/src/vec/common/int_exp.h
+++ b/be/src/vec/common/int_exp.h
@@ -22,6 +22,34 @@
#include <cstdint>
#include <limits>
+#include <utility>
+
+namespace exp_details {
+
+// compile-time exp(v, n) by linear recursion
+template <typename T, T v, std::size_t n>
+constexpr inline const T exp = T(v) * exp<T, v, n - 1>;
+
+template <typename T, T v>
+constexpr inline const T exp<T, v, 0> = 1;
+
+// compile-time exponentiation table { exp(v, I) ... }
+template <typename T, T v, std::size_t... I>
+constexpr inline const T exp_table[] = {exp<T, v, I>...};
+
+// get value from compile-time exponentiation table by a (maybe) runtime offset
+template <typename T, T v, std::size_t... I>
+constexpr T get_exp_helper(std::size_t x, std::index_sequence<I...>) {
+ return exp_table<T, v, I...>[x];
+}
+
+// get_exp_helper with table { exp(v, 0), exp(v, 1) ... exp(v, N - 1) }
+template <typename T, T v, std::size_t N>
+constexpr T get_exp(std::size_t x) {
+ return get_exp_helper<T, v>(x, std::make_index_sequence<N> {});
+}
+
+} // namespace exp_details
/// On overlow, the function returns unspecified value.
@@ -33,103 +61,21 @@ inline uint64_t int_exp10(int x) {
if (x < 0) return 0;
if (x > 19) return std::numeric_limits<uint64_t>::max();
- static const uint64_t table[20] = {1ULL,
- 10ULL,
- 100ULL,
- 1000ULL,
- 10000ULL,
- 100000ULL,
- 1000000ULL,
- 10000000ULL,
- 100000000ULL,
- 1000000000ULL,
- 10000000000ULL,
- 100000000000ULL,
- 1000000000000ULL,
- 10000000000000ULL,
- 100000000000000ULL,
- 1000000000000000ULL,
- 10000000000000000ULL,
- 100000000000000000ULL,
- 1000000000000000000ULL,
- 10000000000000000000ULL};
-
- return table[x];
+ return exp_details::get_exp<uint64_t, 10, 20>(x);
}
namespace common {
-inline int exp10_i32(int x) {
- static const int values[] = {1, 10, 100, 1000, 10000,
- 100000, 1000000, 10000000, 100000000,
1000000000};
- return values[x];
+inline std::int32_t exp10_i32(int x) {
+ return exp_details::get_exp<std::int32_t, 10, 10>(x);
}
-inline int64_t exp10_i64(int x) {
- static const int64_t values[] = {1ll,
- 10ll,
- 100ll,
- 1000ll,
- 10000ll,
- 100000ll,
- 1000000ll,
- 10000000ll,
- 100000000ll,
- 1000000000ll,
- 10000000000ll,
- 100000000000ll,
- 1000000000000ll,
- 10000000000000ll,
- 100000000000000ll,
- 1000000000000000ll,
- 10000000000000000ll,
- 100000000000000000ll,
- 1000000000000000000ll};
- return values[x];
+inline std::int64_t exp10_i64(int x) {
+ return exp_details::get_exp<std::int64_t, 10, 19>(x);
}
inline __int128 exp10_i128(int x) {
- static const __int128 values[] = {
- static_cast<__int128>(1ll),
- static_cast<__int128>(10ll),
- static_cast<__int128>(100ll),
- static_cast<__int128>(1000ll),
- static_cast<__int128>(10000ll),
- static_cast<__int128>(100000ll),
- static_cast<__int128>(1000000ll),
- static_cast<__int128>(10000000ll),
- static_cast<__int128>(100000000ll),
- static_cast<__int128>(1000000000ll),
- static_cast<__int128>(10000000000ll),
- static_cast<__int128>(100000000000ll),
- static_cast<__int128>(1000000000000ll),
- static_cast<__int128>(10000000000000ll),
- static_cast<__int128>(100000000000000ll),
- static_cast<__int128>(1000000000000000ll),
- static_cast<__int128>(10000000000000000ll),
- static_cast<__int128>(100000000000000000ll),
- static_cast<__int128>(1000000000000000000ll),
- static_cast<__int128>(1000000000000000000ll) * 10ll,
- static_cast<__int128>(1000000000000000000ll) * 100ll,
- static_cast<__int128>(1000000000000000000ll) * 1000ll,
- static_cast<__int128>(1000000000000000000ll) * 10000ll,
- static_cast<__int128>(1000000000000000000ll) * 100000ll,
- static_cast<__int128>(1000000000000000000ll) * 1000000ll,
- static_cast<__int128>(1000000000000000000ll) * 10000000ll,
- static_cast<__int128>(1000000000000000000ll) * 100000000ll,
- static_cast<__int128>(1000000000000000000ll) * 1000000000ll,
- static_cast<__int128>(1000000000000000000ll) * 10000000000ll,
- static_cast<__int128>(1000000000000000000ll) * 100000000000ll,
- static_cast<__int128>(1000000000000000000ll) * 1000000000000ll,
- static_cast<__int128>(1000000000000000000ll) * 10000000000000ll,
- static_cast<__int128>(1000000000000000000ll) * 100000000000000ll,
- static_cast<__int128>(1000000000000000000ll) * 1000000000000000ll,
- static_cast<__int128>(1000000000000000000ll) * 10000000000000000ll,
- static_cast<__int128>(1000000000000000000ll) *
100000000000000000ll,
- static_cast<__int128>(1000000000000000000ll) *
100000000000000000ll * 10ll,
- static_cast<__int128>(1000000000000000000ll) *
100000000000000000ll * 100ll,
- static_cast<__int128>(1000000000000000000ll) *
100000000000000000ll * 1000ll};
- return values[x];
+ return exp_details::get_exp<__int128, 10, 39>(x);
}
} // namespace common
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