[Bug tree-optimization/18650] New: Failure in tree-ssa/loop-2.c with powerpc64 with biarch

[jgrimm2 at us dot ibm dot com]

I didn't find a bug report for this yet.

This regressoin roughly started happening Oct 26-27. as it shows up in
testresults from Janis Johson here.  (32-bit default32 compiler.  Regression
only at -m64)

http://gcc.gnu.org/ml/gcc-testresults/2004-10/msg01382.html

Interestingly, this also shows up in my 64-bit default64 compiler but at -m32:

http://gcc.gnu.org/ml/gcc-testresults/2004-10/msg01391.html

The check that is failing in the test case is:

  /* { dg-final { scan-tree-dump-times " \\* 17" 0 "vars" } } */
  /* { dg-final { scan-tree-dump-times " \\+ 17" 1 "vars" } } */

as 17 * iter is not getting reduced.


I played with the testcase a bit using a 32-bit biarch compiler w/ -m64 and
noticed a couple things.

1) Changing the iter var from 'int' to a 'long' seems to let the test pass again
.  The test case is tiny so I'll original code here:

struct bla
{
  char x[187];
  int y;
  char z[253];
} arr_base[100];

void xxx(void)
{
  int  iter;

  for (iter = 0; iter < 100; iter++)
    arr_base[iter].y = 17 * iter;
}



2) Dumps of t52.ivopts pass (from dump-tree-all-all), look funny:

(add_to_evolution
  (loop_nb = 1)
  (chrec_before = 100)
  (to_add = 1)
  (res = {100, +, 4294967295}_1))
  (evolution_function = {100, +, 4294967295}_1))
(set_scalar_evolution
  (scalar = ivtmp.1_5)
  (scalar_evolution = {100, +, 4294967295}_1))
)

,as 4294967295 looks quite peculiar.and would have expected 0 there.   

I'll attach the entire loop-2.c.t52.ivopts for 32 bit and for 64 bit, in case
someone wise in the ways of tree/loops/scalarev has interest.

-- 
           Summary: Failure in tree-ssa/loop-2.c with powerpc64 with biarch
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: jgrimm2 at us dot ibm dot com
                CC: gcc-bugs at gcc dot gnu dot org
  GCC host triplet: powerpc64-linux


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18650