[llvm-dev] RFC: Implementing -fno-delete-null-pointer-checks in clang

[Friedman, Eli via llvm-dev]

On 5/12/2018 9:23 PM, Philip Reames via llvm-dev wrote:
> Fair warning, the following is a devil's advocate position, but it's 
> also a serious question.
>
> Given the entire point of this flag appears to be bug mitigation, why 
> not frame this as a sanitizer?  If we had a hypothetical 
> -fsanitize=dereference which tried to catch dereferenced pointers 
> derived from null, wouldn't that handle the case at hand?

It's called "-fsanitize=null": it catches stuff like "x[3]" where x is 
null. It's not quite complete; we don't check for arithmetic on a null 
pointer.

Yes, that would handle the situation in question, but putting implicit 
null checks all over the place is pretty expensive; I don't think most 
people would turn that on in production.

-Eli

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