From: Martin Kronbichler <kronbichler@lnm.mw.tum.de>
Date: Mon, 30 Mar 2020 06:21:26 +0000 (+0200)
Subject: Avoid unnecessary integer overflow of Utilities::pow()
X-Git-Tag: v9.2.0-rc1~327^2~1
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=165397e2c5d20853385c9540204a35df57505112;p=dealii.git

Avoid unnecessary integer overflow of Utilities::pow()
---

diff --git a/include/deal.II/base/utilities.h b/include/deal.II/base/utilities.h
index a1db035464..04218bd02b 100644
--- a/include/deal.II/base/utilities.h
+++ b/include/deal.II/base/utilities.h
@@ -508,6 +508,10 @@ namespace Utilities
     // if (iexp <= 0)
     //   return 1;
     //
+    // // avoid overflow of one additional recursion with pow(base * base, 0)
+    // if (iexp == 1)
+    //   return base;
+    //
     // // if the current exponent is not divisible by two,
     // // we need to account for that.
     // const unsigned int prefactor = (iexp % 2 == 1) ? base : 1;
@@ -519,9 +523,11 @@ namespace Utilities
 
     static_assert(std::is_integral<T>::value, "Only integral types supported");
 
-    return iexp <= 0 ? 1 :
-                       (((iexp % 2 == 1) ? base : 1) *
-                        dealii::Utilities::pow(base * base, iexp / 2));
+    return iexp <= 0 ?
+             1 :
+             (iexp == 1 ? base :
+                          (((iexp % 2 == 1) ? base : 1) *
+                           dealii::Utilities::pow(base * base, iexp / 2)));
   }
 
   /**