[RFC] Sanitize rtx_addr_can_trap_p_1

[Bernd Edlinger]

Hi,

On Thu, 11 Jun 2015 10:02:03, Jakub Jelinek wrote:
>
> IMHO the
> #if 0
> #endif
> stuff doesn't belong to the patch.
>

I just wanted to leave a hint, how I debugged this function, and how
to assess the performance of the decision that is taken here.

I mean, the boot-strap would certainly pass, if I always return 0 here,
but Eric would'nt like it.

I believe that, when the offset lies within the bounds that are implied by
the current function's stack frame, the access will always be safe.

But there are some very rare false positives, when this function returns 0
on "normal" code, like gcc source code itself, and they are interesting to debug.

Should I better change the #if 0 block into a comment?


> Other than that, as I said already in the PR, I'm in favor of applying it to
> the trunk (only, not release branches) and watching for performance and/or
> wrong-code issues, but Eric is against it. What do others think about it?
>
> From John Regehr's talk at GCC Summit a few years ago I got the
> impression that for people to be able to effectively report bugs in the
> compiler through code generator it is important that discovered bugs in the
> compiler are fixed timely, otherwise it makes life to the reporters much
> harder, because then they'll run into the same still unfixed issue all the
> time.
>

On that, I totally agree.


Thanks
Bernd.