Lift function call out of inner loop

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/tests/suites/test_suite_mpi.function b/tests/suites/test_suite_mpi.function
index a2d312f..5807984 100644
--- a/tests/suites/test_suite_mpi.function
+++ b/tests/suites/test_suite_mpi.function
@@ -1530,6 +1530,8 @@
     }
     else
     {
+        int statistically_safe_all_the_way =
+            is_significantly_above_a_power_of_2( bound_bytes );
         for( b = 0; b < n_bits; b++ )
         {
             mbedtls_test_set_step( 1000000 + b );
@@ -1541,8 +1543,7 @@
              * As an exception, the top bit may legitimately never be set
              * if bound is a power of 2 or only slightly above.
              */
-            if( b != n_bits - 1 ||
-                is_significantly_above_a_power_of_2( bound_bytes ) )
+            if( statistically_safe_all_the_way || b != n_bits - 1 )
             {
                 TEST_ASSERT( stats[b] > 0 );
             }