Re: [PATCH] ubsan: Separate -f{,no-}delete-null-pointer-checks from -fsanitize={null,{,returns-}nonnull-attribute} [PR104426]

[Jakub Jelinek via Gcc-patches]

On Wed, Feb 09, 2022 at 10:03:02AM +0100, Richard Biener wrote:
> I see there are still targets doing sth like
> 
> static void
> msp430_option_override (void)
> {
>   /* The MSP430 architecture can safely dereference a NULL pointer.  In 
> fact,
>      there are memory mapped registers there.  */
>   flag_delete_null_pointer_checks = 0;

Sure, that is the typical embedded target case.
And the user option is in case users are using a typically non-embedded
target case in an embedded way, even on x86_64-linux one can mmap something
at address 0 if one tweaks some kernel config parameters.

I guess I could change
default_addr_space_zero_address_valid from return false; to
  if (!flag_delete_null_pointer_checks)
    return true;
  if (folding_initializer)
    return false;
  if (current_function_decl
      && sanitize_flags_p (SANITIZE_NULL | SANITIZE_NONNULL_ATTRIBUTE
                           | SANITIZE_RETURNS_NONNULL_ATTRIBUTE,
                           current_function_decl))
    return true;
  return false;
and change the i386 one to also call the default version.

Replacing all the flag_delete_null_pointer_checks uses
with some wrappers around the target hook will be less fun, not sure if the
pointer type will be always visible there...

> Did you replace all flag_delete_null_pointer_checks uses?

I did.

>  Can you rename the flag just to be sure?

Sure.

        Jakub