[PATCH] D9107: Fix CombineToPostIndexedLoadStore in DAGCombiner.cpp

Thu Jul 9 00:33:34 PDT 2015

fdeferriere added a comment.

Hi Quentin,

Thanks for your detailed review.

I agree with you that this patch introduces too much regressions to be delivered. I see now two possibilities :

  1- Still rely on this pass to select pre/post addressing modes, but add a kind of "repair" pass after code selection to fix the regressions. This is what we did on our target. However, I am not sure if on ARM this could fix the code to catch again the multiple load/store instructions,

  2- Disable this pass and add a new pass on machine instructions. The main advantage I see is that it can allow to look for pre/post patterns on regions larger than a DAG, which currently is a limitation. For our target, it would probably replace our "repair" pass.

   Should I add a comment "Abandon Revision" to close this patch ?
   Should I log a kind of "request for enhancement" (in Bugzilla ?) to keep a trace of this analysis ?

  Regards,

     - François.

http://reviews.llvm.org/D9107