In my experience (which comes from developing compilers and bringing up operating systems on new architectures with untested compilers), compiler bugs are rarel

In my experience (which comes from developing compilers and bringing up operating systems on new architectures with untested compilers), compiler bugs are rarely 'heisenbugs' in the traditional sense, meaning bugs that go away when you attempt to debug them. Compiler bugs tend to be more deterministic, where some code is being generated incorrectly and it will do the wrong thing every time you execute that code. Changing the optimization settings may cause the bug to go away, but it's still deterministic given the same compiled binary. One exception would be a bug where a compiler is reordering instructions across a memory barrier, but those are even rarer than normal compiler bugs, since compilers are generally paranoid about reordering anything with barrier intrinsics or inline assembly.