Re: New VSI post on Youtube

On 8/15/2024 1:58 AM, Arne Vajhøj wrote:

On 8/14/2024 7:47 PM, Lawrence D'Oliveiro wrote:

On Wed, 14 Aug 2024 14:33:27 -0400, Arne Vajhøj wrote:

And it has different size of long and pointers.

>
If you wanted an integer type that is compatible with pointers, that was
always intptr_t and uintptr_t, surely

  I am not being particular clear.
 I am not saying that:
 default sizeof long C++ x64 <> default sizeof pointer C++ x64
 I am saying that:
 default sizeof long C++ x64 <> default sizeof long C++ Itanium & Alpha
default sizeof pointer C++ x64 <> default sizeof pointer C++ Itanium & Alpha
 and later:
 default sizeof long C++ x64 <> default sizeof long C x64
default sizeof pointer C++ x64 <> default sizeof pointer C x64
 Arne
  

Yes, all good points.  The size_t and offset_t = 32-bits and ptrdiff_t = 32-bits on Alpha/Itanium started the mess years ago.
Personally, I would have kept all the defaults the same as Itanium but got "convinced" to go wider.  The first attempt was ONLY 64-bit pointers on x86 with C++ but things like those pesky descriptors and itemlists got in the way.
I did suggest an LP64, ILP32, etc qualifier but mostly got blank stares from other engineers as "too nerdy"
long == 64-bits has caused us to make changes as prior header writers assumed that long was 32-bits.  They should have all followed Arne's advice and used int32_t and int64_t when specifying their ABIs.
I'll can take some ownership on the changes, but I suffered with years of "John, why is size_t 32-bits?  Why does subtracting two 64-bit pointers only give me a 32-bit result?"