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From: "pexu@gcc-bugzilla.mail.kapsi.fi" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug lto/98275] -flto=auto fails if nthreads_var is zero, must not
 pass -j0
Date: Tue, 15 Dec 2020 10:12:47 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D98275

--- Comment #4 from Pekka S <pexu@gcc-bugzilla.mail.kapsi.fi> ---
(I wrote this prior the ticked was modifed and the patch committed.)

Thanks.

Applied the patch on the latest trunk, built aarch64-none-gcc cross compiler
(mingw64).  Using -flto=3Dauto -v reports `LTO parallelism level set to 1' =
and
`make -f <temporary.mk> -j1 all';  Linking now succeeds.

Tested using GNU make 4.2.93 and 4.3 (msys2).

I do not know whether or not the number of processors should be actually
detectable.  I presume I'll be simply using -flto=3DN (N>1) as it appears t=
o work
just fine.

As a side note behaviour is now slightly different between -flto=3Dauto if
nthreads_var<=3D1 and -flto=3DN where N<=3D1.=