GC thread object
Every GC thread has one of these. It contains all the step specific
- workspaces and other GC thread loacl information. At some later
+ workspaces and other GC thread local information. At some later
point it maybe useful to move this other into the TLS store of the
GC threads
------------------------------------------------------------------------- */
/* -----------------------------------------------------------------------------
The gct variable is thread-local and points to the current thread's
gc_thread structure. It is heavily accessed, so we try to put gct
- into a global register variable if possible.
+ into a global register variable if possible; if we don't have a
+ register then use gcc's __thread extension to create a thread-local
+ variable.
+
+ Even on x86 where registers are scarce, it is worthwhile using a
+ register variable here: I measured about a 2-5% slowdown with the
+ __thread version.
-------------------------------------------------------------------------- */
#define GLOBAL_REG_DECL(type,name,reg) register type name REG(reg);