[Vm-dev] Direct object pointers vs indirect ones pros and cons
Bert Freudenberg
bert at freudenbergs.de
Fri Nov 12 15:44:42 UTC 2010
On 12.11.2010, at 14:41, Igor Stasenko wrote:
> I'm inviting you to make own version of benchmark
I don't think this can be realistically simulated inside Squeak. But possibly you could change the macros in sqMemoryAccess.h to fake an object table access?
I just tried that. Using tinyBenchmarks, byte code performance drops to 63% and sends to 78%.
Now declaring that variable volatile might be overkill as it prevents all caching, but I couldn't quite figure out a more realistic declaration.
- Bert -
#else
# ifndef FAKE_OBJ_TABLE
# define FAKE_OBJ_TABLE
static volatile int FakeObjTable= 0;
# define OBJTABLELOOKUP(oop) (oop + FakeObjTable)
# endif
/* Use macros when static inline functions aren't efficient. */
# define byteAtPointer(ptr) ((sqInt)(*((unsigned char *)(OBJTABLELOOKUP(ptr)))))
# define byteAtPointerput(ptr, val) ((sqInt)(*((unsigned char *)(OBJTABLELOOKUP(ptr)))= (unsigned char)(val)))
# define shortAtPointer(ptr) ((sqInt)(*((short *)(OBJTABLELOOKUP(ptr)))))
# define shortAtPointerput(ptr, val) ((sqInt)(*((short *)(OBJTABLELOOKUP(ptr)))= (short)(val)))
# define intAtPointer(ptr) ((sqInt)(*((unsigned int *)(OBJTABLELOOKUP(ptr)))))
# define intAtPointerput(ptr, val) ((sqInt)(*((unsigned int *)(OBJTABLELOOKUP(ptr)))= (int)(val)))
# define longAtPointer(ptr) ((sqInt)(*((sqInt *)(OBJTABLELOOKUP(ptr)))))
# define longAtPointerput(ptr, val) ((sqInt)(*((sqInt *)(OBJTABLELOOKUP(ptr)))= (sqInt)(val)))
# define oopAtPointer(ptr) (sqInt)(*((sqInt *)OBJTABLELOOKUP(ptr)))
# define oopAtPointerput(ptr, val) (sqInt)(*((sqInt *)OBJTABLELOOKUP(ptr))= (sqInt)val)
# define pointerForOop(oop) ((char *)(sqMemoryBase + ((usqInt)(oop))))
# define oopForPointer(ptr) ((sqInt)(((char *)(ptr)) - (sqMemoryBase)))
# define byteAt(oop) byteAtPointer(pointerForOop(oop))
# define byteAtput(oop, val) byteAtPointerput(pointerForOop(oop), (val))
# define shortAt(oop) shortAtPointer(pointerForOop(oop))
# define shortAtput(oop, val) shortAtPointerput(pointerForOop(oop), (val))
# define longAt(oop) longAtPointer(pointerForOop(oop))
# define longAtput(oop, val) longAtPointerput(pointerForOop(oop), (val))
# define intAt(oop) intAtPointer(pointerForOop(oop))
# define intAtput(oop, val) intAtPointerput(pointerForOop(oop), (val))
# define oopAt(oop) oopAtPointer(pointerForOop(oop))
# define oopAtput(oop, val) oopAtPointerput(pointerForOop(oop), (val))
#endif
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