Re: [PATCH] look harder for MEM_REF operand equality to avoid -Wstringop-truncation (PR 84561)

[Jeff Law <law at redhat dot com>]

On 9/19/18 8:19 AM, Martin Sebor wrote:
> 
> The restrict pass doesn't know about string lengths so it can't
> handle all the warnings about string built-ins (the strlen pass
> now calls into it to issue some).  The strlen pass does so it
> could handle most if not all of them (the folder also calls
> into it to issue some warnings).  It would work even better if
> it were also integrated with the object size pass.
> 
> We're already working on merging strlen with sprintf.  It seems
> to me that the strlen pass would benefit not only from that but
> also from integrating with object size and warn-restrict.  With
> that, -Wstringop-overflow could be moved from builtins.c into
> it as well (and also benefit not only from accurate string
> lengths but also from the more accurate object size info).
> 
> What do you think about that?
Well, given that Wrestrict is already a DOM walk integrating it with
sprintf and strlen would be fairly natural.   In that model we'd come up
with some clever name for the pass.  It'd have an embedded strlen (and
perhaps objsize) analysis.  It's walker would dispatch each statement to
the restrict or sprintf & strlen checker.

> 
> Martin
> 
> PS I don't think I could do more than merger strlen and sprintf
> before stage 1 ends (if even that much) so this would be a longer
> term goal.
Given the time lost to the STRING_CST and range issues, agreed.  It's
not going to happen this stage1.

Jeff