Re: [PATCH bpf-next v2 2/4] selftests: bpf: Add helper to compare socket cookies

On Thu, 1 Oct 2020 at 18:11, Alexei Starovoitov alexei.starovoitov@gmail.com wrote:

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I think this might be the same problem I fixed for libbpf with [0]. Turns out, GCC explicitly calls out (somewhere in their docs) that uninitialized variable warnings work only when compiled in optimized mode, because some internal data structures used to detect this are only maintained in optimized mode build.

Laurenz, can you try compiling your example with -O2?

All of my experiments I did with -O2.

If anybody wants to play with this more: https://godbolt.org/z/77P6P9

Seems like red hat GCC has some special sauce that fixes this behaviour?