[Bug tree-optimization/49069] ICE in gen_cstoredi4, at config/arm/arm.md:7554

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

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49069

Steven Bosscher <steven at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |steven at gcc dot gnu.org
          Component|target                      |tree-optimization
      Known to work|                            |4.7.0
      Known to fail|4.7.0                       |4.6.3

--- Comment #5 from Steven Bosscher <steven at gcc dot gnu.org> 2012-03-01 18:00:55 UTC ---
(In reply to comment #4)
> The real question is why is a cstore operation being called with constants for
> the two operands in the comparison.  If it knows the constants, then it knows
> the result of the comparison and can collapse the entire result.

That is because "GCC: (GNU) 4.6.3" fails to fold a comparison in GIMPLE:

$ cat ice.i.143t.optimized 

;; Function func1 (func1)

func1 ()
{
<bb 2>:
  return;

}



;; Function foo (foo)

foo ()
{
  int D.1291;
  long long unsigned int D.1290;

<bb 2>:
  array1[0] = 0;
  D.1290_6 = 0;
  D.1291_7 = D.1290_6 == 1;
  bar (D.1291_7); [tail call]
  return;

}

TER propagates D.1290_6 into the comparison:

Replacing Expressions
D.1290_6 replace with --> D.1290_6 = 0;
D.1291_7 replace with --> D.1291_7 = D.1290_6 == 1;

The ICE goes away with "-fno-tree-ter". This is not a target bug IMHO, but a
tree-optimization bug.