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[Bug target/69577] [5/6 Regression] wrong code with -fno-forward-propagate -mavx and 128bit arithmetics since r215450
- From: "ubizjak at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Mon, 01 Feb 2016 16:46:01 +0000
- Subject: [Bug target/69577] [5/6 Regression] wrong code with -fno-forward-propagate -mavx and 128bit arithmetics since r215450
- Auto-submitted: auto-generated
- References: <bug-69577-4 at http dot gcc dot gnu dot org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69577
--- Comment #5 from UroÅ Bizjak <ubizjak at gmail dot com> ---
(In reply to Vladimir Makarov from comment #4)
> I believe machine-dependent code is more responsible for it. I remember
> some discussion of it. LRA follows RTL semantics where insn
>
> (set (subreg reg 0) ...)
>
> sets only part of subreg but x86-64 insn implementing it changes all reg.
Please see PR 67609 for the discussion.