On 12/26/2014 04:51 PM, 'Alexander Potapenko' via address-sanitizer wrote:
> How are you going to share the redzone size between all globals in the
> module? They vary depending on the original global size.
Ok, I didn't know that Clang uses adaptive global redzones. AFAIK GCC
does not so it's much easier to just recompute them there.
> What sounds doable is moving |size_with_redzone| calculation to the
> runtime, but this might be too fragile.
Agree, that would also make redzone size computation a part of
compiler-runtime ABI which is bad.
> Regarding |module_name| and |location|, I think we can do a better
job here.
> My hypothesis is that there're unnecessarily many
> __asan_global_source_location structures because |line_no| and
> |column_no| are almost always unique.
> Thus it's better to pull them into __asan_global (we can probably even
> squeeze both fields into a single uptr, though we need to be accurate
> on 32-but systems).
> On the other hand, there're far less unique pairs of module names and
> source file names (aka |location->filename|), so it's natural to group
> them into a single struct:
Right.
> uptr has_dynamic_init; // The above suggestion still applies, we
> can store this flag in |size_with_redzone|
Either that or make this a dedicated int for flags?
> __asan_global_module_filename *location;
Having an int offset here instead of full-blown pointer would save
another 4 bytes + 24 for relocation. But perhaps that's niggling.
-Y
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