On 8 September 2025 16:03:21 CEST, Jason Merrill <[email protected]> wrote:
>On 9/8/25 8:11 AM, Matthias Kretz wrote:
>> Andrew Pinski [Friday, 5 September 2025, 22:57:02 CEST]:
>>>> It seems that Clang and GCC disagree on mangling 80-Bit long double:
>>>>
>>>> https://compiler-explorer.com/z/W1d64PjrP
>>>>
>>>> I like Clang's interpretation of
>>>> https://itanium-cxx-abi.github.io/cxx-abi/
>>>> abi.html#mangle.float better.
>>>
>>> "corresponding to the internal representation" But interpretations
>>> seems valid since there is no mention of the padding bits.
>>> I think GCC is better because it includes the full padding bits.
>>
>> I interpret "internal representation" to say that not the decimal value is
>> printed but rather the bits in memory that make up the floating-point value.
>> And padding bits don't contribute to that value.
>>
>> I wrote "like" above. I have no idea about the wording intent. But using the
>> shorter mangling, and a mangling that is the same on 32- and 64-bit seems
>> preferable. Which is why I "like" it more.
>
>I agree. Can you address that in this patch as well?
I'd really prefer not to. Without this patch my code fails to build. The wrong
long double mangling only breaks compatibility with Clang at this point.
Most importantly, I have no idea how I would determine the number of value
representation bits.
