Fat Binary - Haswell Detection Bug (and fix)

Torbjorn Granlund tg at gmplib.org
Thu Feb 20 20:51:21 UTC 2014

John Sully <john at csquare.ca> writes:

  While testing the latest development code we've discovered that it fails on
  specific Pentium D "Haswell" CPUs.  These CPUs are odd in that they don't
  have the BMI2 instruction set.  Because of this GMP will crash when it
  attempts to execute a MULX.  The specific model is: Intel(R) Pentium(R) CPU
>From Intel's "ARK" pages and from /proc/cpuinfo it seems that AVX is
also missing.

GMP is not prepared for these instruction omissions.  The AVX problem
should preclude your system from working also with your patch applied.

Also, fixing fat builds along is not enough.

I am glad you spotted this problem before 5.2!

Please encrypt, key id 0xC8601622

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