Commits on Mar 24, 2024

1. Fix incorrect check in fpm_shm_free() …

   `if (fpm_shm_size - size > 0)` will be rewritten by the compiler as
   this: `if (fpm_shm_size == size)`, which is undesirable.
   The reason this happens is that both variables are size_t, so
   subtracting them cannot be negative. The only way it can be not > 0, is
   if they're equal because the result will then be 0.
   This means that if we have multiple fpm shm allocations, the shm size
   will not decrease correctly.
   
   To showcase that the compiler actually does this, take a look at this
   isolated case: https://godbolt.org/z/azobdWcrY. Here we can see the
   usage of the compare instruction + cmove, so the "then" branch
   is only done if the variables are equal.

   

   nielsdos committed Mar 24, 2024
   Configuration menu

   • View commit details
   • Copy full SHA for dc908e8
   • Browse repository at this point

   Copy the full SHA

   dc908e8 View commit details

   Browse the repository at this point in the history