[parrot/parrot] b92948: manually enforce invariant

[noreply at github.com]

  Branch: refs/heads/master
  Home:   https://github.com/parrot/parrot

  Commit: b9294804f1f4a7b4988d745bce4ac089ab13993a
      https://github.com/parrot/parrot/commit/b9294804f1f4a7b4988d745bce4ac089ab13993a
  Author: Peter Lobsinger <plobsing at gmail.com>
  Date:   2011-08-31 (Wed, 31 Aug 2011)

  Changed paths:
    M src/gc/gc_gms.c

  Log Message:
  -----------
  manually enforce invariant

Parrot_gc_fixed_allocator_free() will not modify &interp->gc_sys or &pmc->vtable->attr_size
Using local const variables informs the compiler of this invariant which allows it to avoid
redundant loads, leading to a 12.5% reduction in cost (0.05% of Ωη total).