On 10/12/2010 04:41 PM, malc wrote:
> > > > Gives wrong results on Win64.
> >
> > Then it's not HOST_LONG_BITS, it's HOST_POINTER_BITS.
>
> Not quite, [s]size_t/ptrdiff_t are 64 bits wide udner Win64, little
> to do with pointers.
Before (on Win64): sizeof(long) == 4, HOST_LONG_BITS == 64
After: sizeof(long) == 4, HOST_LONG_BITS == 32
If you say HOST_LONG_BITS should be 64, then I say it is poorly named: it
represents sizeof(void*) * CHAR_BIT and should be named HOST_POINTER_BITS.
BTW, HOST_LONG_BITS is used mostly for user-mode emulation, which does not
matter for Win64. In exec-all.h it is used to second-guess
sizeof(tcg_target_long), which would be the size of a pointer. However,
it is safe to give a conservative value based on sizeof(long).
Finally, in other places it is definitely used to mean sizeof(long). Even
though the softmmu is probably not IL32P64-clean, there you have this:
#if HOST_LONG_BITS == 32 && TARGET_LONG_BITS == 32
#define CPU_TLB_ENTRY_BITS 4
#else
#define CPU_TLB_ENTRY_BITS 5
#endif
typedef struct CPUTLBEntry {
/* bit TARGET_LONG_BITS to TARGET_PAGE_BITS : virtual address
bit TARGET_PAGE_BITS-1..4 : Nonzero for accesses that should not
go directly to ram.
bit 3 : indicates that the entry is invalid
bit 2..0 : zero
*/
target_ulong addr_read;
target_ulong addr_write;
target_ulong addr_code;
/* Addend to virtual address to get host address. IO accesses
use the corresponding iotlb value. */
unsigned long addend;
/* padding to get a power of two size */
uint8_t dummy[(1 << CPU_TLB_ENTRY_BITS) -
(sizeof(target_ulong) * 3 +
((-sizeof(target_ulong) * 3) & (sizeof(unsigned long) - 1))
+
sizeof(unsigned long))];
} CPUTLBEntry;
_As things are now_ it is more correct to use sizeof(long), or at
least more conservative.
I can certainly change it to sizeof(void*) in v2, even though I don't think
it's a good idea, but it's your call as a maintainer.
Paolo
