Merge pull request #649 from boostorg/small_int_powers

Try and optimize small integer powers.
boostorg · Jan 17, 2025 · 5e1db68 · 5e1db68
2 parents ad1ee2a + d606acf
commit 5e1db68
Showing 1 changed file with 21 additions and 0 deletions.
diff --git a/include/boost/multiprecision/detail/functions/pow.hpp b/include/boost/multiprecision/detail/functions/pow.hpp
@@ -43,6 +43,27 @@ inline void pow_imp(T& result, const T& t, const U& p, const std::integral_const
       return;
    }
 
+   switch (p)
+   {
+   case 0:
+      result = int_type(1);
+      return;
+   case 1:
+      result = t;
+      return;
+   case 2:
+      eval_multiply(result, t, t);
+      return;
+   case 3:
+      eval_multiply(result, t, t);
+      eval_multiply(result, t);
+      return;
+   case 4:
+      eval_multiply(result, t, t);
+      eval_multiply(result, result);
+      return;
+   }
+
    // This will store the result.
    if (U(p % U(2)) != U(0))
    {