[Bug tree-optimization/88739] [7/8/9 Regression] Big-endian union bug

[wilco at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88739

--- Comment #29 from Wilco <wilco at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #26)

> Did anybody test the patch?  Testing on x86_64 will be quite pointless...

Well that generates _18 = BIT_FIELD_REF <_2, 16, 14>; and becomes:

ubfx    x1, x20, 2, 16

This extracts bits 2-17 of the 30-bit value instead of bits 14-29. The issue is
that we're using a bitfield reference on a value that is claimed not to be a
bitfield in comment 6. So I can't see how using BIT_FIELD_REF could ever work
correctly.