[Bug c/108896] provide "element_count" attribute to give more context to __builtin_dynamic_object_size() and -fsanitize=bounds

[qinzhao at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108896

--- Comment #44 from qinzhao at gcc dot gnu.org ---
(In reply to Martin Uecker from comment #43)
> works with the bounds checking code?  Does it also interact with the object
> size pass?

both array-bounds sanitizer and object size pass are updated to use this new
attribute. 
I will refine the patch a little bit before posting it in the next week.