int128 error

Touros Spoon
Mon Jan 3 14:36:00 GMT 2011


I have read the manual, but my understanding was that the Intel core2 duo 
processors supported 128 bit width (from the intel core2 instruction set 
manual: "...and enabling support for 128 bit integers..."). I assumed that 
the reason long long was showing up as 64 bits instead of 128 was part of 
the problem that was causing __int128 to not work (perhaps a compiler flag I 
had missed or something else).


----- Original Message ----- 
From: "Jonathan Wakely" <>
To: "Touros Spoon" <>
Cc: <>; <>
Sent: Monday, January 03, 2011 3:30 PM
Subject: Re: int128 error

> On 3 January 2011 08:36, Touros Spoon wrote:
>> Jeffrey,
>> thanks for the quick response. I actually tried appending LL to the end 
>> of
>> the value, but the compiler is still complaining, which isnt surprising
>> because a test shows that long long has a sizeof of 8 bytes, whereas
>> __int128_t reports 16 bytes.
> Read the fabulous manual:
> "There is no support in GCC to express an integer constant of type
> __int128 for targets having long long integer with less then 128 bit
> width."
> Since your target's long long is not 128 bits wide, you cannot express
> that constant. 

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