[Bug c++/86871] [8/9 Regression] ICE: gimple check: expected gimple_assign(error_mark), have gimple_call(trunc_mod_expr) in gimple_assign_lhs, at gimple.h:2462

[rsandifo at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86871

--- Comment #8 from rsandifo at gcc dot gnu.org <rsandifo at gcc dot gnu.org> 
---
Author: rsandifo
Date: Thu Aug  9 16:03:25 2018
New Revision: 263451

URL: https://gcc.gnu.org/viewcvs?rev=263451&root=gcc&view=rev
Log:
Allow inner-loop reductions with variable-length vectors

While working on PR 86871, I noticed we were being overly restrictive
when handling variable-length vectors.  For:

  for (i : ...)
    {
      res = ...;
      for (j : ...)
        res op= ...;
      a[i] = res;
    }

we don't need a reduction operation (although we do for double
reductions like:

  res = ...;
  for (i : ...)
    for (j : ...)
      res op= ...;
  a[i] = res;

which must still be rejected).

2018-08-08  Richard Sandiford  <richard.sandif...@arm.com>

gcc/
        * tree-vect-loop.c (vectorizable_reduction): Allow inner-loop
        reductions for variable-length vectors.

gcc/testsuite/
        * gcc.target/aarch64/sve/reduc_8.c: New test.

Added:
    trunk/gcc/testsuite/gcc.target/aarch64/sve/reduc_8.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/tree-vect-loop.c