Can _mm_crc32_u64() return a value that is bigger than MAX_UINT32?

[Alex Lyakas]

Hi Segher,

If we can know what is the generated machine instruction, we can ask further 
here.

Thanks for your help,
Alex.


-----Original Message----- 
From: Segher Boessenkool
Sent: Monday, February 12, 2018 7:04 PM
To: Alex Lyakas
Cc: Eitan Azriel ; gcc-help@gcc.gnu.org ; hjl.tools@gmail.com
Subject: Re: Can _mm_crc32_u64() return a value that is bigger than 
MAX_UINT32?

Hi Alex,

On Mon, Feb 12, 2018 at 06:19:29PM +0200, Alex Lyakas wrote:
> Can you confirm then, that despite returning a 64-bit value, the result
> will never actually cross the maximal 32-bit value? Can you perhaps point
> us at gcc code, so that we can try to ensure that?

Documentation says it should not.  I would assume GCC implements this
correctly.  I don't know where in the code this is handled (if at all,
the generated machine instruction should have that property, there is
nothing the compiler needs to do extra).


Segher