[MacPorts] #41614: always build gmp from source? (Fix SIGILL on Core2Du)

[MacPorts]

#41614: always build gmp from source? (Fix SIGILL on Core2Du)
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 Reporter:  kurtjaeke@…  |      Owner:  macports-tickets@…
     Type:  defect       |     Status:  new
 Priority:  Normal       |  Milestone:
Component:  ports        |    Version:  2.2.1
 Keywords:               |       Port:
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 There have been a number of issues with gmp failing with SIGILL when
 installed from binary archives: #40439, #40621, #41364, #41555.
 These issues are difficult to debug, since the symptoms are, amongst
 others, strange crashes during compilation.

 Background: gmp detects available CPU instructions during "configure".
 This information is used in the build process to conditionally enable
 assembler code.
 In the bugs mentioned above, the affected architecture seems to be
 Core2Duo, the first x86_64 CPUs Apple shipped (IIRC) (the MacPorts build
 farm is supposedly more modern).

 This brings up the question: should gmp  '''always''' be built from
 source? Is this a viable approach to solving this issue? Thanks for
 discussing.

 Attached is a piece of Fortran code which triggers this issue. Run your
 favorite Fortran compiler with the '''-v''' flag, and if the compiler
 backend ('''f951''' for any gcc) crashes with SIGILL, this problem affects
 you.

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Ticket URL: <https://trac.macports.org/ticket/41614>
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