[Bug other/60816] New: Optimzed arm code generates infinite loop via branch instruction branching to current program counter

[andrew.j.c.parker at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60816

            Bug ID: 60816
           Summary: Optimzed arm code generates infinite loop via branch
                    instruction branching to current program counter
           Product: gcc
           Version: 4.8.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: other
          Assignee: unassigned at gcc dot gnu.org
          Reporter: andrew.j.c.parker at gmail dot com

Created attachment 32583
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=32583&action=edit
Zip file containing repro cpp, compiler output, preprocessed file and GCC build
script

The bug is with GCC 4.8.3 compiler for ARM bare metal.  It has been produced on
both:

build=linux (ubuntu) host=Windows target=arm
build=osx host=osx target=arm

The source comes from https://launchpad.net/gcc-arm-embedded/+download,
specifically the q1 release
https://launchpad.net/gcc-arm-embedded/4.8/4.8-2014-q1-update/+download/gcc-arm-none-eabi-4_8-2014q1-20140314-src.tar.bz2. 

I have also reproduced it with the Android NDK r9 and the arm 4.8 toolchain. 
The bug isn't present in 4.7.4.

Attached is a simple cpp file attached to reproduce bug.  Command line is:

gcc -c -O3 compiler_bug.cpp

The unlinked object file exhibits the problem.  The generated assembly for the
main function is:

00000000 <main>:
   0:    eafffffe     b    0 <main>

There are some comments in the code about what changes you can make to "remove"
the bug.

Also attached is the compiler output and the preprocessed .ii file.