[Bug tree-optimization/92860] [9/10/11/12 regression] Global flags affected by -O settings are clobbered by optimize attribute

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92860

--- Comment #63 from David Binderman <dcb314 at hotmail dot com> ---
(In reply to Martin Liška from comment #62)
> Can't reproduce with the current master:

Righto. This is proving unexpectedly hard to reproduce.

EITHER: I search various values of march= to find out which
ones work and which ones don't.

OR: I do a fishing trip for revisions some unknown time before
2020-06-11 (the known bad date), to find a known good date, then
run git bisect from there.

In furtherance of option 2 and given that Jun 2020 is long enough
ago that the git rev-list will have expired (it is only valid for 90 days),
am I correct in thinking that something like

git rev-list -n 1 --first-parent --before="2020-01-01" master

will give me a git hash of a revision of the first day of year 2020
and so

git checkout `that git hash`

will get me to that date, so I can run a build ?