Re: [Qemu-devel] [PATCH 0/1] Change default CFLAGS to -O3

[Christian Borntraeger]

On 01/09/2017 11:01 AM, Jin Guojie wrote:
> * in configure, the default optimization level is changed to O3.
> * Tested successfully on following machines:
> 
>   | Host machine | Host OS  | qemu-system | Debian ISO  |
>   |-----------------------------------------------------|
>   |   x86 64     | Fedora25 |    i386     |    i386     |
>   | mips 64 le   | Fedora25 |    i386     |    i386     |
> 
> Signed-off-by: Jin Guojie <address@hidden>
> 
> Jin Guojie (1):
>   Change default CFLAGS to -O3
> 
>  configure | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 

There are some compilers that trigger some maybe Warnings with -O3
e.g.

      CC      block/vmdk.o
    /home/cborntra/REPOS/qemu/block/vmdk.c: In function ‘vmdk_open_vmdk4’:
    /home/cborntra/REPOS/qemu/block/vmdk.c:718:24: error: ‘extent’ may be
    used uninitialized in this function [-Werror=maybe-uninitialized]
         extent->has_marker = le32_to_cpu(header.flags) & VMDK4_FLAG_MARKER;
                            ^
    /home/cborntra/REPOS/qemu/block/vmdk.c: In function ‘vmdk_open_sparse’:
    /home/cborntra/REPOS/qemu/block/vmdk.c:530:9: error: ‘extent’ may be
    used uninitialized in this function [-Werror=maybe-uninitialized]
         ret = vmdk_init_tables(bs, extent, errp);
             ^
    /home/cborntra/REPOS/qemu/block/vmdk.c:509:17: note: ‘extent’ was
    declared here
         VmdkExtent *extent;
                     ^
    /home/cborntra/REPOS/qemu/block/vmdk.c: In function
    ‘vmdk_open_desc_file.isra.12’:
    /home/cborntra/REPOS/qemu/block/vmdk.c:873:39: error: ‘extent’ may be
    used uninitialized in this function [-Werror=maybe-uninitialized]
                 extent->flat_start_offset = flat_offset << 9;
                                           ^
    /home/cborntra/REPOS/qemu/block/vmdk.c:803:17: note: ‘extent’ was
    declared here
         VmdkExtent *extent;
                     ^
    cc1: all warnings being treated as errors
    /home/cborntra/REPOS/qemu/rules.mak:60: recipe for target 'block/vmdk.o'
    failed


I have started fixing those some time ago but had no time yet finishing that.
Totally messy patches (in terms of patch description) at
https://github.com/borntraeger/qemu/commits/o3

Christian