From: johnrreagan@earthlink.net
On 8/15/2025 7:48 PM, Arne Vajhøj wrote:
> On 8/15/2025 1:33 PM, Simon Clubley wrote:
>> On 2025-08-15, Dan Cross wrote:
>>> In article <107n93n$13rjm$1@dont-email.me>,
>>> Simon Clubley wrote:
>>>> On 2025-08-12, Arne Vajhøj wrote:
>>>>> if(args->arg_count == 2 && args->arg_type[0] == STRING_RESULT
&&
>>>>> args->arg_type[1] == INT_RESULT)
>>>>
>>>> Is it guaranteed that arg_type[] will always have at least elements ?
>>>> If not, that's dangerous unless the compiler you are using does
>>>> expression short-circuiting.
>>>
>>> C is well-defined in this regard. Boolean expressions in C,
>>> created by combining logical subexpressions with the `&&` and
>>> `||` operators, are documented to use short-circuiting behavior.
>
>> Unless it's explicit in the language syntax itself, and given that
>> I write code in multiple languages, I have long written code that
>> assumes implicit[*] short-circuiting is not available.
>>
>> As such, whether implicit short-circuiting is available or not is
>> not really that important to me, but I will admit I didn't realise
>> C had it.
>>
>> [*] By implicit short-circuiting I mean something that's only defined
>> in the language standard or implemented in a compiler, instead of some
>> explicit syntax in the language itself to state short-circuiting is
>> available.
>
> In general I like the idea of writing code in a way that does
> not require the reader to have memorized ten thousand things from
> the language spec.
>
> But I do not consider this a matter of remembering the specific
> details about an operator - I consider this a matter of remembering
> what operator a symbol represent.
>
> I consider "short circuiting AND" and "non short circuiting AND"
> to be two different operators.
BTW, while the C frontend always generates the "short-circuiting" AND
and OR intermediate opcodes, the GEM optimizer works to detect if that
is really needed. It is hoping to hoist something from the right-hand
side out of a loop (which happens more than you think) and on Itanium it
can even put both left and right in the same bundle if possible (which
doesn't happen all that much)
>
> And in C then && is the first operator not the second operator.
>
> And understanding what operator each symbol represent is not
> detail but core. IMHO.
>
> Arne
>
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