Hi,
On Tue 30 Jun 2009 00:23, l...@gnu.org (Ludovic Courtès) writes:
> "Andy Wingo" <wi...@pobox.com> writes:
>
>> +#define BV_FIXABLE_INT_REF(stem, fn_stem, type, size) \
>> +{ \
>> + long i; \
>> + ARGS2 (bv, idx); \
>> + VM_VALIDATE_BYTEVECTOR (bv); \
>> + if (SCM_LIKELY (SCM_I_INUMP (idx) \
>> + && ((i = SCM_I_INUM (idx)) >= 0) \
>> + && (i < SCM_BYTEVECTOR_LENGTH (bv)) \
>> + && (i % size == 0))) \
>> + RETURN (SCM_I_MAKINUM (*(scm_t_##type*) \
>> + (SCM_BYTEVECTOR_CONTENTS (bv) + i))); \
>
> Did you test this on SPARC or some such? I'm 90% sure
> `(bv-u32-ref bv 1)' would lead to SIGBUS there, due to the unaligned access.
> This is why `INTEGER_REF ()' in `bytevectors.c' uses memcpy(3).
Wouldn't the i % size == 0 case catch that? (This is used in native-ref
instructions)
>> + else \
>> + RETURN (scm_bytevector_##fn_stem##_ref (bv, idx)); \
>
> In this case, we pay the overhead twice (type-checking et al.).
It's probably an error -- idx is not an inum, is out of range, or is
unaligned...
> Given that there's some duplication with `bytevectors.c', maybe we could
> share some of the accessor macros between both files?
Perhaps! The one difference is that we can fast-path only the normal
cases here, calling out to those functions to handle stranger things
(like unaligned access).
Andy
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