[Bug target/66930] [5 Regression]: gengtype.c is miscompiled during stage2

[kkojima at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66930

--- Comment #8 from Kazumoto Kojima <kkojima at gcc dot gnu.org> ---
(In reply to John Paul Adrian Glaubitz from comment #7)
> What do you mean? Using -O1 will trigger all kinds of bugs? Or is it rather
> about PR target/66358?

Just my 2 cents.  Even on the primary targets, bootstrap with other
than '-g -O2' are not so well tested.  Most packages are built with
-O2, aren't they?  After all, -O1 should work but not safer than -O2,
IMO.  O2 does many optimizations, and some of them might cause bug.
OTOH, some of them simplify the intermediate code.  With -O1, we could
see highly complex intermediate code in some cases and they might cause
problem.  We have just seen an example in this PR.