On 9/13/2021 8:18 AM, Michael Matz wrote:
Hello,
On Mon, 13 Sep 2021, Jeff Law via Gcc-patches wrote:
So it looks like there's some undefined behavior going on, even before
my patch. I'd like to get some feedback, because this is usually the
type of problems I see in the presence of a smarter threader... things
get shuffled around, problematic code gets isolated, and warning
passes have an easier time (or sometimes harder time) diagnosing
things.
The original issue was PRE hanging, so I'd lean towards keeping the test as-is
and instead twiddling any warning flags we can to make the diagnostics go
away.
Or use this changed test avoiding the issues that I see with -W -Wall on
this testcase. I've verified that it still hangs before r194358 and is
fixed by that revision.
Generally I think, our testsuite, even for ICEs or these kinds of hangs,
should make an effort to try to write conforming code; if at all possible.
Here it is possible.
(I don't know if the new threader causes additional warnings, of course,
but at least the problems with sequence points and uninitialized use of
'j' aren't necessary to reproduce the bug)
Well, if we can twiddle the test to remove the undefined behavior
without compromising its original intent, then that's obviously better -)
jeff
