Re: Re: gcc 3.3 warnings about strict-aliasing rules

On 2003-08-25 14:54:48, Ard Biesheuvel wrote: > Casting to void* instead of void** cures the problem. As the cast Yes, but why? > I would consider it a justified change. I don't think there will be > consequences for the validity of the optimization. I don't know if with some optimizations void* or zval pointers need special alignment. > Code will have to be changed regardless, as it's not the function > invocation but the cast itself that triggers the warning. Yes, or we would be on the safe side if we compile with -fno-strict-aliasing, then gcc doesn't do such expression based optimizations. Or (as I have seen on some patches for other projects after a search for the gcc warning message) we could change the zval** data to something like this: union { zval **zval; void *ptr; } data; call zend_hash_find(..., &data.ptr) and after this use data.zval. Access via unions is allowed because then the data must be correctly aligned for both types. The gcc generated code for this variant only uses some other registers, otherwise it seems similar. Stefan -- Stefan Röhrich stefan@roehri.ch, sr@linux.de http://www.roehri.ch/~sr/