[Bug tree-optimization/65443] New: Don't peel last iteration from loop in transform_to_exit_first_loop

[vries at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65443

            Bug ID: 65443
           Summary: Don't peel last iteration from loop in
                    transform_to_exit_first_loop
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: vries at gcc dot gnu.org

tree-parloops.c (
https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=gcc/tree-parloops.c;h=fbb9eebddcf23e0c3498668e7aaa4708d302f255;hb=HEAD#l1503
):
...
   TODO: the common case is that latch of the loop is empty and immediately
   follows the loop exit.  In this case, it would be better not to copy the
   body of the loop, but only move the entry of the loop directly before the
   exit check and increase the number of iterations of the loop by one.
   This may need some additional preconditioning in case NIT = ~0.
   REDUCTION_LIST describes the reductions in LOOP.  */

static void
transform_to_exit_first_loop (struct loop *loop,
                  reduction_info_table_type *reduction_list,
                  tree nit)
...