[Bug tree-optimization/56049] New: [4.8 Regression] Simplification to constants not done

[tkoenig at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56049



             Bug #: 56049

           Summary: [4.8 Regression] Simplification to constants not done

    Classification: Unclassified

           Product: gcc

           Version: 4.8.0

            Status: UNCONFIRMED

          Severity: normal

          Priority: P3

         Component: tree-optimization

        AssignedTo: unassig...@gcc.gnu.org

        ReportedBy: tkoe...@gcc.gnu.org





>From http://gcc.gnu.org/ml/fortran/2013-01/msg00158.html :



program inline



    integer i

    integer a(8,8), b(8,8)



    a = 0

    do i = 1, 10000000

        call add(b, a, 1)

        a = b

    end do



    print *, a



contains



    subroutine add(b, a, o)

        integer, intent(inout) :: b(8,8)

        integer, intent(in) :: a(8,8), o

        b = a + o

    end subroutine add



end program inline



is simplified all the way to the final constant with 4.6 and

4.7 (example for 4.6.2):



;; Function inline (MAIN__) (executed once)



inline ()

{

  struct array2_integer(kind=4) parm.3;

  struct __st_parameter_dt dt_parm.2;

  integer(kind=4) a[64];



<bb 2>:

  a = {};

  MEM[(integer(kind=4)[64] *)&a] = 10000000;

  MEM[(integer(kind=4)[64] *)&a + 4B] = 10000000;

  MEM[(integer(kind=4)[64] *)&a + 8B] = 10000000;

  MEM[(integer(kind=4)[64] *)&a + 12B] = 10000000;

  MEM[(integer(kind=4)[64] *)&a + 16B] = 10000000;

  MEM[(integer(kind=4)[64] *)&a + 20B] = 10000000;

  MEM[(integer(kind=4)[64] *)&a + 24B] = 10000000;

  MEM[(integer(kind=4)[64] *)&a + 28B] = 10000000;

  MEM[(integer(kind=4)[64] *)&a + 32B] = 10000000;



... and so on.  Current trunk converts this to



;; Function inline (MAIN__, funcdef_no=0, decl_uid=1874, cgraph_uid=1)

(executed once)



inline ()

{

  vector(4) integer(kind=4) vect_var_.16;

  vector(4) integer(kind=4) vect_var_.15;

  vector(4) integer(kind=4) vect_var_.14;

  struct array2_integer(kind=4) parm.3;

  struct __st_parameter_dt dt_parm.2;

  integer(kind=4) b[64];

  integer(kind=4) a[64];

  unsigned int ivtmp_153;

  unsigned int ivtmp_154;



  <bb 2>:

  a = {};



  <bb 3>:

  # ivtmp_154 = PHI <10000000(2), ivtmp_153(4)>

  vect_var_.14_1 = MEM[(integer(kind=4)[64] *)&a];

  vect_var_.15_42 = MEM[(integer(kind=4)[64] *)&a + 16B];

  vect_var_.16_43 = vect_var_.14_1 + { 1, 1, 1, 1 };

  vect_var_.16_44 = vect_var_.15_42 + { 1, 1, 1, 1 };

  MEM[(integer(kind=4)[64] *)&b] = vect_var_.16_43;

  MEM[(integer(kind=4)[64] *)&b + 16B] = vect_var_.16_44;

  vect_var_.14_71 = MEM[(integer(kind=4)[64] *)&a + 32B];

  vect_var_.15_77 = MEM[(integer(kind=4)[64] *)&a + 48B];

  vect_var_.16_78 = vect_var_.14_71 + { 1, 1, 1, 1 };

  vect_var_.16_79 = vect_var_.15_77 + { 1, 1, 1, 1 };