[Bug target/57637] New: Miscompare on 178.galgel in SPEC2000 on arm

[ktkachov at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57637

            Bug ID: 57637
           Summary: Miscompare on 178.galgel in SPEC2000 on arm
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ktkachov at gcc dot gnu.org
                CC: bernds at codesourcery dot com, zhenqiang.chen at linaro dot org
            Target: armv7l-unknown-linux-gnueabihf

We're getting a miscompare on the 178.galgel benchmark in SPEC2000 on
armv7l-unknown-linux-gnueabihf, on a Cortex-A15.
The .mis file just says 'galgel.out' short.

Bisection shows it started with r199439.

2013-05-30 Bernd Schmidt <bernds@codesourcery.com>
Zhenqiang Chen <zhenqiang.chen@linaro.org>

    config/arm/arm-protos.h: Add and update function protos.
    config/arm/arm.c (use_simple_return_p): New added.
    (thumb2_expand_return): Check simple_return flag.
    config/arm/arm.md: Add simple_return and conditional simple_return.
    config/arm/iterators.md: Add iterator for return and simple_return.


The compiler was configured: "--with-cpu=cortex-a15 --with-fpu=neon-vfpv4
--with-mode=thumb --with-float=hard --enable-languages=c,c++,fortran"

The flags for the benchmark are -ffixed-form -mthumb -mcpu=cortex-a15
-mfpu=neon-vfpv4 -mfloat-abi=hard -O3.
It works with -O1, fails at -O2 and -O3