[Bug c/69319] New: Suspect compiler bug

[freddy77 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69319

            Bug ID: 69319
           Summary: Suspect compiler bug
           Product: gcc
           Version: 5.3.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: freddy77 at gmail dot com
  Target Milestone: ---

Created attachment 37374
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=37374&action=edit
test program, single C file with only system includes

Hi, I found a strange problem with optimized code.
The code uses an hand written dynamic double linked list (circular).
There are some trick to make see the list as an item of the list.
After some work I manage to get a small test program.
I don't really understand why this specific code crash.
Trying to read the assembly code (x86_64) looks like the compiler is assuming
some value on first iteration of the a "check" loop causing an assertion to
fail.
I tested the program with Ubuntu 15.10 compiler (5.2.1) and a Fedora 22
(5.3.1), all x86_64.

Test program is really small. I manage to get a single C file only with system
includes.