Only make objects long lived if they are on the GC heap #2317
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babygrimes
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tannewt
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Nov 25, 2019
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When using frozen bytecode compiled into the "firmware" (obviously not quite true in the Unix port), and said frozen bytecode has mp_type_bytes object(s) defined, and said object(s) are used as default arguments to functions generated SIGSEGV. After researching, I found this is due to the behavior of making certain things "long_lived". My specific failure occurred in make_str_long_lived, specifically trying to assign str->data, but in my case, "str" is a "ROM" pointer. In other words it is not a heap address, so the concept of making that long lived doesn't seem to apply.
This fix uses VERIFY_PTR (moved from gc.c to gc.h) to check the argument passed to make_obj_long_lived and do nothing if the pointer is not verified as a GC heap block pointer.
I don't have a debugging capability on my actual microcontrollers, but in concept this patch seems safe since the concept of a "long live" GC pointer doesn't seem to apply if the pointer can't be verified to begin with.