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From: "meissner at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/91512] [10 Regression] Fortran compile time
 regression.
Date: Thu, 23 Apr 2020 19:47:41 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D91512

--- Comment #31 from Michael Meissner <meissner at gcc dot gnu.org> ---
For the Spec 2017 521.wrf_r benchmark on little endian PowerPC power9 syste=
ms,
there was no difference in runtime between a normal run using -Ofast
-mcpu=3Dpower9 and one with -Ofast -mcpu=3Dpower9 -fno-inline-arg-packing.

Of the seven rate benchmarks in Spec 2017 that use Fortran (548.exchange2_r,
503.bwaves_r, 507.cactuBSSN_r, 521.wrf_r, 527.cam4_r, 549.fotonik3d_r, and
554.roms_r) none of them vary by more tha 0.7% depending on whether the swi=
tch
is used or not.

I used the compiler checked out from the master branch on March 27, 2020 to
build and run the benchmarks.

As others have said, using -fno-inline-arg-packing does dramatically reduce=
 the
time it takes to compile 521.wrf_r.=