[Bug target/72827] [7 Regression] gnat bootstrap broken on powerpc64le-linux-gnu

["wschmidt at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=72827

--- Comment #18 from Bill Schmidt <wschmidt at gcc dot gnu.org> ---
The frame pointer adjustments are introduced in 263r.split2.  I haven't yet run
down the offending split, but the pattern being split is a *vsx_movti_64bit.  I
know we've had changes in the back end fairly recently involving TImode moves,
so this may be why the problem didn't show up before.

I think DSE relies on the stack being fairly well behaved; it probably
shouldn't be making assumptions when the frame pointer is messed with like this
during the function.  Which means doing this sort of thing is bad for
optimization anyway, and should be avoided.  I'll look further.