[Bug tree-optimization/36967] New: segfault in is_gimple_real_type with -fpredictive-commoning -ffast-math

["janis at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

After the merge of the tuples branch GCC segfaults on a Fortran benchmark with
lots of calculations involving three-dimensional arrays in nested loops.  This
testcase reproduces the problem when compiled on powerpc-linux with "-O2
-ffast-math -fpredictive-commoning":

      subroutine foo(x,y,n)
      integer n
      real*8 y(n,n,n),x(n,n,n)
      integer k, j, i
      do k = 2, n-1
        do j = 2, n-1
          do I = 2, n-1
            y(i,j,k) = y(i,j,k)
     +        + (x(i-1,j-1,k)
     +           +  x(i,j-1,k-1)
     +           +  x(i,j+1,k-1)
     +           +  x(i,j+1,k+1)
     +           +  x(i+1,j,k+1))
     +        + (x(i-1,j-1,k-1)
     +           +  x(i+1,j-1,k-1)
     +           +  x(i-1,j+1,k-1)
     +           +  x(i+1,j+1,k-1)
     +           +  x(i-1,j+1,k+1)
     +           +  x(i+1,j+1,k+1))
          enddo
        enddo
      enddo
      return

Here's some of the stack trace:

#0  0x103a60f0 in is_gimple_reg_type (type=0x0)
    at /home/janis/gcc_trunk_anonsvn/gcc/gcc/gimple.c:2867
#1  0x103a66e8 in is_gimple_val (t=0xf7f152c0)
    at /home/janis/gcc_trunk_anonsvn/gcc/gcc/gimple.c:2968
#2  0x103a0408 in gimple_assign_copy_p (gs=0xf7eeca40)
    at /home/janis/gcc_trunk_anonsvn/gcc/gcc/gimple.c:1848
#3  0x106357a4 in remove_stmt (stmt=0xf7ee4880)
    at /home/janis/gcc_trunk_anonsvn/gcc/gcc/tree-predcom.c:1709
#4  0x10635910 in execute_pred_commoning_chain (loop=0xf7ee6e70, 
    chain=0x10f1edf0, tmp_vars=0x10ef45dc)
    at /home/janis/gcc_trunk_anonsvn/gcc/gcc/tree-predcom.c:1756
#5  0x10635ce0 in execute_pred_commoning (loop=0xf7ee6e70, chains=0x10f1ef50, 
    tmp_vars=0x10ef45dc)
    at /home/janis/gcc_trunk_anonsvn/gcc/gcc/tree-predcom.c:1821
#6  0x10636078 in execute_pred_commoning_cbck (loop=0xf7ee6e70, 
    data=0xff8afc30)
    at /home/janis/gcc_trunk_anonsvn/gcc/gcc/tree-predcom.c:1886
#7  0x107057ec in tree_transform_and_unroll_loop (loop=0xf7ee6e70, factor=2, 
    exit=0xf7ef0600, desc=0xff8afbf8, 
    transform=0x10636024 <execute_pred_commoning_cbck>, data=0xff8afc30)
    at /home/janis/gcc_trunk_anonsvn/gcc/gcc/tree-ssa-loop-manip.c:1014
#8  0x106398b8 in tree_predictive_commoning_loop (loop=0xf7ee6e70)
    at /home/janis/gcc_trunk_anonsvn/gcc/gcc/tree-predcom.c:2617

Notice that the pointer passed to is_gimple_reg_type is NULL; it's not
expecting that.


-- 
           Summary: segfault in is_gimple_real_type with -fpredictive-
                    commoning -ffast-math
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: janis at gcc dot gnu dot org
GCC target triplet: powerpc-unknown-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36967