[Bug target/69577] [5/6 Regression] wrong code with -fno-forward-propagate -mavx and 128bit arithmetics since r215450

[rth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69577

Richard Henderson <rth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |rth at gcc dot gnu.org

--- Comment #10 from Richard Henderson <rth at gcc dot gnu.org> ---
This does look plausible as a replacement for the hacks
I added in cannot_change_mode_class.