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From: "jens.seifert at de dot ibm.com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/106770] PPCLE: Unnecessary xxpermdi before mfvsrd
Date: Mon, 27 Feb 2023 17:57:03 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D106770

--- Comment #4 from Jens Seifert <jens.seifert at de dot ibm.com> ---
PPCLE with no special option means -mcpu=3Dpower8 -maltivec  (altivecle to =
be mor
precise).

vec_promote(<double value>, 1) should be a noop on ppcle. But value gets
splatted to both left and right part of vector register. =3D> 2 unnecesary
xxpermdi
The rest of the operations are done on left and right part.

vec_extract(<vector double>, 1) should be noop on ppcle. But value gets tak=
en
from right part of register which requires a xxpermdi

Overall 3 unnecessary xxpermdi. Don't know why the right part of register g=
ets
"preferred".=