This is a workaround (hack) for a gcc optimization issue (PR 99551).
Without this the generated code may evaluate the expression in the
cold path which causes performance regression for small allocations
in the memory tagging disabled (common) case.
Reviewed-by: DJ Delorie <dj@redhat.com>
must be a macro that produces a compile time constant if passed
a constant literal. */
if (__glibc_unlikely (mtag_enabled))
- req = (req + (__MTAG_GRANULE_SIZE - 1)) &
- ~(size_t)(__MTAG_GRANULE_SIZE - 1);
+ {
+ /* Ensure this is not evaluated if !mtag_enabled, see gcc PR 99551. */
+ asm ("");
+
+ req = (req + (__MTAG_GRANULE_SIZE - 1)) &
+ ~(size_t)(__MTAG_GRANULE_SIZE - 1);
+ }
*sz = request2size (req);
return true;