[Bug tree-optimization/52686] New: SLP crashes with WIDEN_LSHIFT_EXPR

[Bug tree-optimization/52686] New: SLP crashes with WIDEN_LSHIFT_EXPR

[uweigand at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52686

             Bug #: 52686
           Summary: SLP crashes with WIDEN_LSHIFT_EXPR
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: uweigand@gcc.gnu.org


When building the following test case:

unsigned int output[4];

void test (unsigned short *p)
{
  unsigned int x = *p;
  if (x)
    {
      output[0] = x << 1;
      output[1] = x << 1;
      output[2] = x << 1;
      output[3] = x << 1;
    }
}

GCC crashes with various symptoms (segmentation fault if checking is disabled;
assertion failures along the lines of "vector VEC(tree,base) index domain
error, in vect_create_vectorized_promotion_stmts at tree-vect-stmts.c:2130" if
checking is enabled) when building on ARM with -O1 -ftree-vectorize -mfpu=neon
-mfloat-abi=softfp.

[Bug tree-optimization/52686] SLP crashes with WIDEN_LSHIFT_EXPR

[uweigand at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52686

--- Comment #2 from Ulrich Weigand <uweigand at gcc dot gnu.org> 2012-03-23 15:42:00 UTC ---
Created attachment 26968
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=26968
Handle WIDEN_LSHIFT_EXPR in vect_get_smallest_scalar_type

The attached patch fixes the ICEs for me.

[Bug tree-optimization/52686] SLP crashes with WIDEN_LSHIFT_EXPR

[uweigand at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52686

Ulrich Weigand <uweigand at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2012-03-23
     Ever Confirmed|0                           |1

--- Comment #1 from Ulrich Weigand <uweigand at gcc dot gnu.org> 2012-03-23 15:38:43 UTC ---
It seems the root cause of all the memory problems is that
vect_get_smallest_scalar_type neglects to handle WIDEN_LSHIFT_EXPR, which
causes the SLP pass to mis-compute the number of statements needed to vectorize
the expression.

[Bug tree-optimization/52686] SLP crashes with WIDEN_LSHIFT_EXPR

[uweigand at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52686

--- Comment #3 from Ulrich Weigand <uweigand at gcc dot gnu.org> 2012-03-26 13:13:14 UTC ---
Author: uweigand
Date: Mon Mar 26 13:13:07 2012
New Revision: 185795

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=185795
Log:
    gcc/
    PR tree-optimization/52686
    * tree-vect-data-refs.c (vect_get_smallest_scalar_type): Handle
    WIDEN_LSHIFT_EXPR.

    gcc/testsuite/
    PR tree-optimization/52686
    * gcc.target/arm/pr52686.c: New test.

Added:
    trunk/gcc/testsuite/gcc.target/arm/pr52686.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/tree-vect-data-refs.c

[Bug tree-optimization/52686] SLP crashes with WIDEN_LSHIFT_EXPR

[uweigand at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52686

Ulrich Weigand <uweigand at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED

--- Comment #4 from Ulrich Weigand <uweigand at gcc dot gnu.org> 2012-03-26 13:16:30 UTC ---
Fixed.