impact of infinite loops on sanitizers

[bi6c]

Hello.
I have a question regarding the behavior of UBSAN and ASAN in the presence of infinite loops in C programs.
Do infinite loops affect the ability of UBSAN and ASAN to detect and report issues? (with compiler optimization -O1, -O2,...)

[nikic]

It's not super clear what you're asking here, but infinite loops affect sanitizers just like everything else does. If an infinite loop and its preceding code is optimized away prior to sanitizer instrumentation, then it won't be instrumented...

[bi6c]

I found this case that UBSAN reported load of misaligned address error when compiling with clang-17 at -O2, but clang-19-init (trunk) does not report. It also happened when the optimization level is at -O3.
https://godbolt.org/z/cex4qMYe8

[bi6c]

Sorry I might paste the wrong link. Here is the updated link: https://godbolt.org/z/cex4qMYe8