https://gcc.gnu.org/ml/gcc-patches/2015-07/msg01604.html

https://gcc.gnu.org/ml/gcc-patches/2015-07/msg01604.html

[Kenneth Zadeck]

I had the following conversation with richi about this patch.

Sorry to reply off thread, but i do net read this group in my mailer.


[09:00]    zadeck    richi: i am reviewing a patch and i have a couple 
of questions, do you have a second to look at something?
[09:00]    richi    zadeck: sure
[09:01]    zadeck    the patch is 
https://gcc.gnu.org/ml/gcc-patches/2015-07/msg01604.html
[09:01]    zadeck    he has set up the data flow problem correctly, but 
i worry that this really is not the right way to solve this problem.
[09:02]    richi    let me look at the problem
[09:03]    zadeck    in particular, the only way he can demonstrate this 
problem in c is with an uninitialized variable.    It seems that a 
normal correct program would not normally have this kind of issue unless 
there was some upstream bug coming out of the middle end.
[09:04]    richi    even for his Ada case it's not initialized it seems
[09:06]    richi    zadeck: I've added a comment to the PR and requested 
info
[09:06]    zadeck    my ada is as good as my German.
[09:07]    zadeck    the thing is that if you turn this into a truly 
must problem, it will disable a lot of legit transformations.
[09:08]    richi    yep
[09:09]    zadeck    thanks
[09:09]    richi    lets see if he can point to a different issue
[09:09]    richi    or produce a C testcase for us
[09:13]    jakub    richi: yeah; if it is Ada only thing and Ada 
uninitialized variable must have some special properties, then they'd 
better use some on the side flag for whether it is initialized, or zero 
initialize or whatever Ada expects
[09:15]    richi    jakub: from what I understand of Ada the testcase 
doesn't look like such a case
[09:16]    richi    jakub: so the actual bug is likely somewhere else




Kenny