Re: 64 bit string offsets

On 29 Aug 2014, at 16:49, Anatol Belski <anatol.php@belski.net> wrote: > Hi, > > while refining the big string support, it turned out that we've an issue. > The syntax like $s[42] = 'x'; is currently inconsistend, because we have > uint32 for string offsets. This actually means, the behaviour is currently > only available in the old style and can handle not more than 2gb big > strings. > > Also discussed with Laruence on IRC and he actually expressed the concern > that we pay overhead on that. From my side I was investigating on that and > could suggest several solutions for that: > > - stay with the old behavior (indexes would be able to handle only 2gb > strings, this is the status quo) > - implement a function like in JS String.charAt() as alternative > - turn to some temp_variable solution we currently have in PHP5. Laruence > told be that dropping temp_variable was one of the improvementes. > Actually, the string index functionality is utilized in two opcodes, so > maybe that were just a local case. > > Anyway not talking about touching zval, as that would grow by 8 bytes with > a size_t str_offset. Just maybe there were another solution I oversee? We don’t need to actually support >2GB string indexing realistically. As I understand it, we’re using size_t because it’s the proper type for string lengths, not because we need >2GB strings. I’d just leave things as they are… though I suppose there might be some benefit to switching to size_t for string offsets. Does that avoid a cast in the generated assembly? -- Andrea Faulds http://ajf.me/