On 7/30/2021 10:19 AM, Aldy Hernandez via Libc-alpha wrote:
There's a new jump threader in GCC which is much more aggressive, and
may trigger latent problems with other warning passes, especially
-Warray-bounds, -Woverflow, and -Wuninitialized.
Do your problems go away if you take out commit 2e96b5f14e?
I have notes throughout the commit analyzing variants of the above
warnings (for example my addendum to gcc.c-torture/compile/pr83510.c).
So far, all the warnings I've seen are legitimate jump threading
opportunities that we are now doing, but which throw off the warning
passes.
Before the inclusion of the new threader, I had warned that this could
happen. Perhaps we'll have to come up a way to reduce the false
positives.
I should be able to get you testcases for at least some of these. I
strongly suspect it's the new threader. First up will be the iconf
stringop-overflow failures which should hit your inbox shortly.
Jeff
