[MacPorts] #38766: Building atlas with clang 3.3 needs excessive memory

[MacPorts]

#38766: Building atlas with clang 3.3 needs excessive memory
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  Reporter:  bgschaid@…  |      Owner:  vince@…
      Type:  defect      |     Status:  new
  Priority:  Normal      |  Milestone:
 Component:  ports       |    Version:  2.1.3
Resolution:              |   Keywords:
      Port:  atlas       |
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Comment (by vince@…):

 Hallo!

 Clang 3.2 has been released with a bug in the AVX assembler, so if you try
 to compile it on a recent hardware, it will produce a faulty code. The bug
 has been fixed early in the clang3.3 stage, so it is a logical choice to
 use it as a compiler, even though it is only a developement version. If
 you use clang3.2 or gcc instead, you have to give up using AVX and
 downgrade to SSE, and you lose 50% bandwidth.

 As for the memory use, I’d bet this is not caused directly by Clang, but
 by the way Atlas probes the machine in order to pick up the best
 parameters for compilation: it tries every possible combination and then
 evaluate the resulting code by running it in a loop. By the way, Atlas has
 precompiled values for gcc47, so it has not to go through this time-
 consuming phase. However, since clang failed to pass most of the tests up
 to the 3.3 version, no values are available for it.

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Ticket URL: <https://trac.macports.org/ticket/38766#comment:4>
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