https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111095
--- Comment #4 from mengli ming <dale.mengli.ming at proton dot me> --- (In reply to David Malcolm from comment #1) > Thanks for filing this bug. > > This looks similar to bug 111213. > > Adding -fdump-ipa-analyzer=stderr shows that at -O1 and above, the entire > body of the function is optimized away before the analyzer even sees it > (presumably due to undefined behavior). > > My hypothesis is that the optimizer sees the undefined behavior and > optimizes the function away (but I haven't checked the details). > > If that's the case, that's a strong argument that the analyzer should run > earlier. I'll open a bug about that. Hi David, Under the -O0 optimization level, I found another issue with this case. After commenting out irrelevant code like `for (int i = 0; i < 1; i++) ;` or `union a h;`, the analyzer reports an out-of-bound warning. Moreover, changing `*g = 0;` to `*g = 1;` also triggers the out-of-bound warning. It's puzzling.
