https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87744
--- Comment #17 from GCC Commits ---
The master branch has been updated by Jonathan Wakely :
https://gcc.gnu.org/g:c74131e77f1a6b7afe700d3526a8992dc9744b0c
commit r14-9038-gc74131e77f1a6b7afe700d3526a8992dc9744b0c
Author: Jonathan Wakely
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87744
--- Comment #16 from GCC Commits ---
The master branch has been updated by Jonathan Wakely :
https://gcc.gnu.org/g:7f3d900684ad989164114f25eb46a33871c6533d
commit r14-9028-g7f3d900684ad989164114f25eb46a33871c6533d
Author: Jonathan Wakely
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87744
--- Comment #15 from GCC Commits ---
The master branch has been updated by Jonathan Wakely :
https://gcc.gnu.org/g:c9ce332b557bb95987d038d98ea929cdfd1eae1d
commit r14-8998-gc9ce332b557bb95987d038d98ea929cdfd1eae1d
Author: Jonathan Wakely
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87744
--- Comment #14 from Jonathan Wakely ---
(In reply to Lewis Fox from comment #12)
> (In reply to Jonathan Wakely from comment #2)
>
> My original comment about libc++ was in reference to the LLVM bugzilla
> report #27839:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87744
--- Comment #13 from Jonathan Wakely ---
(In reply to Jakub Jelinek from comment #11)
> Though, if it is common enough, one could try to optimize the __ll[0] == 0
> && __xx[0] == 0 case, one can do then either 32x32->64 or 64x64->64
>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87744
--- Comment #12 from Lewis Fox ---
(In reply to Jonathan Wakely from comment #2)
My original comment about libc++ was in reference to the LLVM bugzilla report
#27839: https://bugs.llvm.org/show_bug.cgi?id=27839
It looks like the issue you
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87744
--- Comment #11 from Jakub Jelinek ---
(In reply to Jakub Jelinek from comment #10)
> As discussed on IRC, probably the
> if (!__builtin_mul_overflow(__l._M_lo, __x, &__lo))
> optimization isn't a good idea, because most likely the compiler will
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87744
Jakub Jelinek changed:
What|Removed |Added
CC||jakub at gcc dot gnu.org
--- Comment
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87744
--- Comment #9 from Jonathan Wakely ---
Oops yes!
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87744
--- Comment #8 from Jakub Jelinek ---
if (!__l._M_hi)
{
__l._M_lo %= __m;
return __l;
}
auto __n = __l._M_hi ? __builtin_clzll(__l._M_hi)
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87744
Jonathan Wakely changed:
What|Removed |Added
Attachment #57346|0 |1
is obsolete|
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87744
--- Comment #6 from Jonathan Wakely ---
(In reply to Jakub Jelinek from comment #4)
> Why not just
> __l._M_hi += __builtin_uaddll_overflow(__l._M_lo, __c,
> &__l._M_lo);
> and similarly for subtraction?
No good reason - I'll change
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87744
Jonathan Wakely changed:
What|Removed |Added
Attachment #57345|0 |1
is obsolete|
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87744
--- Comment #4 from Jakub Jelinek ---
(In reply to Jonathan Wakely from comment #1)
> Created attachment 57345 [details]
> Use 64-bit integers to do 128-bit arithmetic
>
> This patch defines a custom type that implements the necessary 128-bit
>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87744
--- Comment #3 from Jonathan Wakely ---
Based on that, I'm not sure what libc++ does is actually better than what
libstdc++ does today (i.e. refuse to compile if the results would be wrong).
I think the patch above would make sense though. I'm
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87744
--- Comment #2 from Jonathan Wakely ---
(In reply to Lewis Fox from comment #0)
> libc++'s
> implementation of linear_congruential_engine (though libc++ incorrectly uses
> Schrage's method).
I haven't checked what libc++ actually does, but it
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87744
--- Comment #1 from Jonathan Wakely ---
Created attachment 57345
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=57345=edit
Use 64-bit integers to do 128-bit arithmetic
This patch defines a custom type that implements the necessary 128-bit
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87744
Jonathan Wakely changed:
What|Removed |Added
Status|UNCONFIRMED |NEW
Last reconfirmed|
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