[Bug tree-optimization/54899] [4.7 Regression] -fpredictive-commoning and -ftree-vectorize optimizations generate a nonsensical binary which segfaults

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54899



Richard Biener <rguenth at gcc dot gnu.org> changed:



           What    |Removed                     |Added

----------------------------------------------------------------------------

             Status|UNCONFIRMED                 |NEW

      Known to work|                            |4.6.4, 4.8.0

           Keywords|                            |wrong-code

   Last reconfirmed|                            |2012-10-11

          Component|c++                         |tree-optimization

     Ever Confirmed|0                           |1

            Summary|-fpredictive-commoning and  |[4.7 Regression]

                   |-ftree-vectorize            |-fpredictive-commoning and

                   |optimizations generate a    |-ftree-vectorize

                   |nonsensical binary which    |optimizations generate a

                   |segfaults                   |nonsensical binary which

                   |                            |segfaults

   Target Milestone|---                         |4.7.3

      Known to fail|                            |4.7.2



--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> 2012-10-11 
13:57:50 UTC ---

predcom introduces



  D.2600_40 = MEM[(const double &)D.2413_2].mData[4294967295];

  D.2601_38 = MEM[(const double &)D.2413_2].mData[0];

  D.2602_19 = MEM[(const double &)D.2413_2].mData[1];



this is mData[-1], a reconstructed array access, D.2413_2 is &this_1(D)->b.



Not sure how predcom arrives at this ... on trunk there is no predcom

performed and Instead the base is this_1(D) + 24.