-#if defined(THREADED_RTS)
-
-#define GLOBAL_REG_DECL(type,name,reg) register type name REG(reg);
-
-#define SET_GCT(to) gct = (to)
-
-
-
-#if (defined(i386_HOST_ARCH) && defined(linux_HOST_OS))
-// Using __thread is better than stealing a register on x86/Linux, because
-// we have too few registers available. In my tests it was worth
-// about 5% in GC performance, but of course that might change as gcc
-// improves. -- SDM 2009/04/03
-//
-// We ought to do the same on MacOS X, but __thread is not
-// supported there yet (gcc 4.0.1).
-
-extern __thread gc_thread* gct;
-#define DECLARE_GCT __thread gc_thread* gct;
-
-
-#elif defined(sparc_TARGET_ARCH)
-// On SPARC we can't pin gct to a register. Names like %l1 are just offsets
-// into the register window, which change on each function call.
-//
-// There are eight global (non-window) registers, but they're used for other purposes.
-// %g0 -- always zero
-// %g1 -- volatile over function calls, used by the linker
-// %g2-%g3 -- used as scratch regs by the C compiler (caller saves)
-// %g4 -- volatile over function calls, used by the linker
-// %g5-%g7 -- reserved by the OS
-
-extern __thread gc_thread* gct;
-#define DECLARE_GCT __thread gc_thread* gct;
-
-
-#elif defined(REG_Base) && !defined(i386_HOST_ARCH)
-// on i386, REG_Base is %ebx which is also used for PIC, so we don't
-// want to steal it
-
-GLOBAL_REG_DECL(gc_thread*, gct, REG_Base)
-#define DECLARE_GCT /* nothing */
-
-
-#elif defined(REG_R1)
-
-GLOBAL_REG_DECL(gc_thread*, gct, REG_R1)
-#define DECLARE_GCT /* nothing */
-
-
-#elif defined(__GNUC__)
-
-extern __thread gc_thread* gct;
-#define DECLARE_GCT __thread gc_thread* gct;
-
-#else
-
-#error Cannot find a way to declare the thread-local gct
-
-#endif
-
-#else // not the threaded RTS
-
-extern StgWord8 the_gc_thread[];
-
-#define gct ((gc_thread*)&the_gc_thread)
-#define SET_GCT(to) /*nothing*/
-#define DECLARE_GCT /*nothing*/
-
-#endif
-