I seem to be having troubles with YAFU on a Colab Instance if I try to use USE_AVX2=1 as an option. I'm getting quite regular failures of the following sort:

Code:

./yafu 83627958813331634770105456990581223975460530782647023599500689759334189187309703
fac: factoring 83627958813331634770105456990581223975460530782647023599500689759334189187309703
fac: using pretesting plan: normal
fac: no tune info: using qs/gnfs crossover of 93 digits
div: primes less than 10000
rho: x^2 + 3, starting 200 iterations on C80
rho: x^2 + 2, starting 200 iterations on C80
rho: x^2 + 1, starting 200 iterations on C80
pm1: starting B1 = 150K, B2 = gmp-ecm default on C80
ecm: 30/30 curves on C80, B1=2K, B2=gmp-ecm default
ecm: 74/74 curves on C80, B1=11K, B2=gmp-ecm default
ecm: 188/188 curves on C80, B1=50K, B2=gmp-ecm default, ETA: 0 sec
starting SIQS on c80: 83627958813331634770105456990581223975460530782647023599500689759334189187309703
==== sieving in progress ( 2 threads): 48096 relations needed ====
==== Press ctrl-c to abort and save state ====

and then it returns.

The CPU is:

Code:

Intel(R) Xeon(R) CPU @ 2.00GHz

and I'm using the trunk branch.

If I compile with USE_SSE41=1 and not USE_AVX2=1, I only see a failure very rarely. I am not including msieve or NFS at all.

Any help appreciated. . .