mpi: small rearrangement in is-power-of-two function.

* mpi.c (s_mp_ispow2): Delay call to s_highest_bit until that
value is actually needed. Perhaps the compiler does the code
motion, but let's write the code that way.

1 files changed, 2 insertions, 4 deletions

diff --git a/mpi/mpi.c b/mpi/mpi.c
index 355a8d1f..0d5e0beb 100644
--- a/mpi/mpi.c
+++ b/mpi/mpi.c
@@ -4037,7 +4037,7 @@ mp_size s_mp_ispow2(mp_int *v)
 {
   mp_digit d, *dp;
   mp_size uv = USED(v);
-  mp_size extra = 0, ix;
+  mp_size ix;
 
   d = DIGIT(v, uv - 1); /* most significant digit of v */
 
@@ -4045,8 +4045,6 @@ mp_size s_mp_ispow2(mp_int *v)
   if ((d & (d - 1)) != 0)
     return MP_SIZE_MAX; /* not a power of two */
 
-  extra = s_highest_bit(d) - 1;
-
   if (uv >= 2) {
     ix = uv - 2;
     dp = DIGITS(v) + ix;
@@ -4059,7 +4057,7 @@ mp_size s_mp_ispow2(mp_int *v)
     }
   }
 
-  return ((uv - 1) * DIGIT_BIT) + extra;
+  return ((uv - 1) * DIGIT_BIT) + s_highest_bit(d) - 1;
 }
 
 int s_mp_ispow2d(mp_digit d)