[PING][PATCH] enable ranger and caching in pass_waccess

Andrew MacLeod amacleod@redhat.com
Wed Aug 25 16:14:30 GMT 2021


On 8/25/21 11:20 AM, Martin Sebor wrote:
> Ping: Andrew, did I answer your questions?  Do you (or anyone else)
> have any other comments on the latest patch below?
>
> https://gcc.gnu.org/pipermail/gcc-patches/2021-August/577865.html


I wasn't attempting to block it, its outside my review purview..

I was merely commenting that you should not need a pointer to a 
range_query at all anymore


>
>>
>>>
>>> Are you planning to transition to using the get_range_query() 
>>> interface instead of keeping a range_query pointer in the 
>>> pointer_query class?
>>
>> This pass and to a smaller extent the pointer_query class that's
>> used by it and the strlen pass are still a work in progress.
>> I also still need to convert the strlen pass to use Ranger and
>> I expect it will take some changes to pointer_query.  So at that
>> point, if going through get_range_query (cfun) everywhere is what
>> you recommend, I'm happy to do it.
>>
absolutely. you should not need to even know whether you have a ranger 
instance running or not. get_range_query will give you whichever is 
active, and there is ALWAYS something active.. defaulting to the global 
version.

the code in get_range() seems to be the end of the call chain which uses 
the pointer and should be consolidated to something much simpler

      if (rvals && stmt)
         {
           if (!rvals->range_of_expr (vr, val, stmt))
             return NULL_TREE;

         <...>

       // ?? This entire function should use get_range_query or
    get_global_range_query (),
       // instead of doing something different for RVALS and global ranges.

       if (!get_global_range_query ()->range_of_expr (vr, val) ||
    vr.undefined_p ())
         return NULL_TREE;


This entire section can boil down to something like

if (!get_range_query (cfun)->range_of_expr (vr, val, stmt))
   return NULL;


>>
>>
>> PS There has been an effort to get rid of global variables from GCC,
>> or, as the first step, to avoid accessing them directly(*).  If and
>> when that happens, it seems like each pass will have to store either
>> the ranger instance as a member (directly or indirectly, via a member
>> of a class that stores it) or the function passed to pass::execute()
>> if it wants to access either.
>>
>> [*] https://gcc.gnu.org/pipermail/gcc-patches/2021-June/573975.html
>> The patch at the link above wasn't approved but IIUC removing globals
>> from GCC is still a goal.
>
I have no idea what direction that is going, but the net effect will be 
the same in the end.  You'll be calling get_range_query() with either 
the function pointer, or the pass pointer, or something.. but you should 
never need to pass around  a pointer to either a ranger or range-query.  
As I said earlier, this will likely be a pass property and accessed thru 
the pass eventually... but until then, use what we have.. cfun.  It'll 
be trivial to transition down the road to whatever the ultimate solution is.

Andrew




More information about the Gcc-patches mailing list