fixup! Clean up the erts_bs_get_integer_2() function in erl_bits.c

bjorng · Oct 27, 2024 · 718b302 · 718b302
1 parent b0cbc70
commit 718b302
Showing 1 changed file with 7 additions and 6 deletions.
diff --git a/erts/emulator/beam/erl_bits.c b/erts/emulator/beam/erl_bits.c
@@ -202,6 +202,8 @@ erts_bs_get_integer_2(Process *p, Uint num_bits,
     Uint v32;
     int sgn = 0;
     Eterm res = THE_NON_VALUE;
+    Uint byte_offset;
+    const byte* bp;
 
     if (num_bits == 0) {
         return SMALL_ZERO;
@@ -212,6 +214,9 @@ erts_bs_get_integer_2(Process *p, Uint num_bits,
         return THE_NON_VALUE;
     }
 
+    byte_offset = BYTE_OFFSET(sb->start);
+    bp = erl_sub_bits_get_base(sb) + byte_offset;
+
     /*
      * Special cases for field sizes up to the size of Uint.
      */
@@ -221,11 +226,10 @@ erts_bs_get_integer_2(Process *p, Uint num_bits,
          * All bits are in one byte in the binary. We only need
          * shift them right and mask them.
          */
-        Uint b = *(erl_sub_bits_get_base(sb) + BYTE_OFFSET(sb->start));
-        Uint mask = MAKE_MASK(num_bits);
+        Uint b = bp[0];
         sb->start += num_bits;
         b >>= 8 - offs - num_bits;
-        b &= mask;
+        b &= MAKE_MASK(num_bits);
         MAYBE_SIGN_EXTEND(flags, b, num_bits);
         return make_small(b);
     } else if (num_bits <= 8) {
@@ -234,8 +238,6 @@ erts_bs_get_integer_2(Process *p, Uint num_bits,
          * combine the bytes to a word first, and then shift right and
          * mask to extract the bits.
          */
-        Uint byte_offset = BYTE_OFFSET(sb->start);
-        const byte* bp = erl_sub_bits_get_base(sb) + byte_offset;
         Uint w = bp[0] << 8 | bp[1];
         Uint mask = MAKE_MASK(num_bits);
         sb->start += num_bits;
@@ -248,7 +250,6 @@ erts_bs_get_integer_2(Process *p, Uint num_bits,
          * Handle field sizes from 9 up to SMALL_BITS-1 bits, big-endian,
          * stored in at least two bytes.
          */
-        const byte* bp = erl_sub_bits_get_base(sb) + BYTE_OFFSET(sb->start);
         Uint n;
         Uint w;