gcc generates invalid instructions when it detects a NULL ptr deref

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Just FYI
https://bugs.launchpad.net/gcc-arm-embedded/+bug/1586033

This is apparently a feature, not a bug

Of course this only applies to NULLs that can be detected at compile time, but it's "smart" enough to do this if you do

if(x == NULL)
y=*x;

So if you actually want to read address zero, you need to resort to a ~~function call~~ or maybe inline ASM.

edit:
It's smart enough to detect some function calls too.

edit:
Or maybe compiler options https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63803