#21064: Enable NTL's '-march=native' more cautiously
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Reporter: leif | Owner: leif
Type: defect | Status: needs_review
Priority: blocker | Milestone: sage-7.3
Component: packages: | Resolution:
standard |
Keywords: assembler shlx | Merged in:
mulx |
Authors: Leif Leonhardy | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
u/leif/enable_NTL_native_more_safely|
7e1ceb270804b7525db553d35be29ccecc03206a
Dependencies: | Stopgaps:
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Comment (by leif):
Replying to [comment:4 fbissey]:
> Option 3 forced by brain to work and conduct some little checks on my
machine. Option 3 is more complicated but more refined in its treatment of
corner cases, and it is well documented (all options are documented well
enough).
>
> Being refined is always going to be more complicated. Anyone has
contacted Victor to see if he could make a check that would also test the
assembler in a new version? That would be even better in my opinion. But
in the meantime. I'll vote for (3) against my better judgement about its
complexity.
Yep, it became more lengthy than I first thought. (Empathy with Apple fan
boys is no good. ;-) )
W.r.t. upstream, thinking more about it I came to the conclusion that it's
pretty ok to assume that the parts of the toolchain fit, and for an
ordinary user manually running NTL's `configure` it's easy to just pass
`NATIVE=off` if something doesn't work.
On the other hand, I actually intended to add proper feature checks (for
each "non-standard" ISA extension enabled by `-march=native`, which of
course is a moving target), probably also with some runtime checks
(actually ''executing'' instructions), because what CPUID reports isn't
always correct (and hence GCC could be "wrong" as well), be it a crippled
''and'' flawed Intel chip, or a VM bug.
--
Ticket URL: <https://trac.sagemath.org/ticket/21064#comment:5>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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