[Info-vax] Itanium support is back in GCC 15

[Arne Vajhøj]

On 2/24/2025 12:42 PM, Michael S wrote:
> On Thu, 7 Nov 2024 16:48:49 -0500
> Arne Vajhøj <arne at vajhoej.dk> wrote:
>> On 11/7/2024 12:33 PM, gcalliet wrote:
>>> Le 04/11/2024 à 21:16, Arne Vajhøj a écrit :
>>>> I wish someone would volunteer to create VMS support
>>>> in GCC 16 or whatever!
>>>>   
>>> Because I created (canadian method) Gnat Ada (on gcc) for VMS
>>> Itanium, and because we were on gcc 4.7, there is some work ahead,
>>> but why not :)
>>>
>>> The big issue is the step to gcc 5, where they upgraded to c++
>>> mode. It is one of the reasons why Adacore didn't continue support
>>> of gnat ada on VMS in 2015.
>>
>> VMS x86-64 has a better C++ compiler than VMS Itanium.

That comment was about C++ standard compliance not performance.

C++ VMS x86-64 is clang which in the (older) clang version used
should mean C++14 while C++ VMS Itanium is very very old (like
C++ 98 old).

> According to the benchmarks that you posted here several months (a
> year?) ago, VMS x86-64 compilers are quite awful comparatively to
> x86-64 compilers available on Windows/Linux/BSD.
> Do you want to say that VMS Itanium compilers are worse?

I believe the conclusion was that the VMS x86-64 compilers except C++
was slower than C/C++ on other OS and C++ on VMS.

My guess is that it is a combination of the GEM to LLVM translation
and a desire from VSI to be a little conservative (prioritizing
correctness over speed).

Arne