[Bug c/61373] New: neon registers restored incorrectly with -mapcs-frame -O -fno-omit-frame-pointer

[breiten at lexmark dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61373

            Bug ID: 61373
           Summary: neon registers restored incorrectly with -mapcs-frame
                    -O -fno-omit-frame-pointer
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: breiten at lexmark dot com

The attached file is a preprocessed and stripped version of: 
http://cgit.freedesktop.org/systemd/systemd/plain/src/shared/siphash24.c

When compiled with -O -march=armv7-a -mfpu=neon -mapcs-frame
-fno-omit-frame-pointer, the neon registers are restored incorrectly.  The are
stored to the stack with:

    fstmfdd    sp!, {d8, d9, d10, d11}
    fstmfdd    sp!, {d14}

but restored [out of order] with:

    fldmfdd    ip!, {d8-d11}
    fldmfdd    ip!, {d14}

This does not occur at -O0 or -O2 or without -mapcs-frame.

With -fno-omit-frame-pointer removed, the two fldmfdd instructions are swapped
and appear correct.  This occurs on both 4.8.1 (as patched by poky-1.5) and
4.8.3.

Here's my gcc version:
Using built-in specs.
COLLECT_GCC=/bonus/scratch/gcc483/poky/myproject/tmp/sysroots/x86_64-linux/usr/bin/armv7a-vfp-neon-poky-linux-gnueabi/arm-poky-linux-gnueabi-gcc
COLLECT_LTO_WRAPPER=/bonus/scratch/gcc483/poky/myproject/tmp/sysroots/x86_64-linux/usr/libexec/armv7a-vfp-neon-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/4.8.3/lto-wrapper
Target: arm-poky-linux-gnueabi
Configured with:
/bonus/scratch/gcc483/poky/myproject/tmp/work-shared/gcc-4.8.3-r0/gcc-4.8.3/configure
--build=x86_64-linux --host=x86_64-linux --target=arm-poky-linux-gnueabi
--prefix=/bonus/scratch/gcc483/poky/myproject/tmp/sysroots/x86_64-linux/usr
--exec_prefix=/bonus/scratch/gcc483/poky/myproject/tmp/sysroots/x86_64-linux/usr
--bindir=/bonus/scratch/gcc483/poky/myproject/tmp/sysroots/x86_64-linux/usr/bin/armv7a-vfp-neon-poky-linux-gnueabi
--sbindir=/bonus/scratch/gcc483/poky/myproject/tmp/sysroots/x86_64-linux/usr/bin/armv7a-vfp-neon-poky-linux-gnueabi
--libexecdir=/bonus/scratch/gcc483/poky/myproject/tmp/sysroots/x86_64-linux/usr/libexec/armv7a-vfp-neon-poky-linux-gnueabi
--datadir=/bonus/scratch/gcc483/poky/myproject/tmp/sysroots/x86_64-linux/usr/share
--sysconfdir=/bonus/scratch/gcc483/poky/myproject/tmp/sysroots/x86_64-linux/etc
--sharedstatedir=/bonus/scratch/gcc483/poky/myproject/tmp/sysroots/x86_64-linux/com
--localstatedir=/bonus/scratch/gcc483/poky/myproject/tmp/sysroots/x86_64-linux/var
--libdir=/bonus/scratch/gcc483/poky/myproject/tmp/sysroots/x86_64-linux/usr/lib/armv7a-vfp-neon-poky-linux-gnueabi
--includedir=/bonus/scratch/gcc483/poky/myproject/tmp/sysroots/x86_64-linux/usr/include
--oldincludedir=/bonus/scratch/gcc483/poky/myproject/tmp/sysroots/x86_64-linux/usr/include
--infodir=/bonus/scratch/gcc483/poky/myproject/tmp/sysroots/x86_64-linux/usr/share/info
--mandir=/bonus/scratch/gcc483/poky/myproject/tmp/sysroots/x86_64-linux/usr/share/man
--disable-silent-rules --disable-dependency-tracking
--with-libtool-sysroot=/bonus/scratch/gcc483/poky/myproject/tmp/sysroots/x86_64-linux
--enable-clocale=generic --with-gnu-ld --enable-shared --enable-languages=c,c++
--enable-threads=posix --disable-multilib --enable-c99 --enable-long-long
--enable-symvers=gnu --enable-libstdcxx-pch
--program-prefix=arm-poky-linux-gnueabi- --without-local-prefix
--enable-target-optspace --enable-lto --enable-libssp --disable-bootstrap
--disable-libmudflap --with-system-zlib --with-linker-hash-style=gnu
--enable-linker-build-id --with-ppl=no --with-cloog=no
--enable-checking=release --enable-cheaders=c_global
--with-gxx-include-dir=/bonus/scratch/gcc483/poky/myproject/tmp/sysroots/myarmcpu/usr/include/c++
--with-sysroot=/bonus/scratch/gcc483/poky/myproject/tmp/sysroots/myarmcpu
--with-build-sysroot=/bonus/scratch/gcc483/poky/myproject/tmp/sysroots/myarmcpu
--enable-poison-system-directories --disable-libunwind-exceptions
--with-mpfr=/bonus/scratch/gcc483/poky/myproject/tmp/sysroots/x86_64-linux/usr
--with-system-zlib --disable-nls
Thread model: posix
gcc version 4.8.3 (GCC)