[Qemu-devel] qemu-upstream compile failure in intel_iommu.c:vtd_context_device_invalidate

[Olaf Hering]

Compiling qemu-xen at 2ce1d30 ("xenfb.c: avoid expensive loops when prod
<= out_cons") leads to this error with -O1:

xen.git/tools/qemu-xen-dir/hw/i386/intel_iommu.c: In function 
‘vtd_context_device_invalidate’:
xen.git/tools/qemu-xen-dir/hw/i386/intel_iommu.c:911:46: error: ‘mask’ may be 
used uninitialized in this function [-Werror=maybe-uninitialized]
             if (vtd_as && ((devfn_it & mask) == (devfn & mask))) {
                                              ^
It works with -O2. From the code flow its clear that mask is always
initialized. Looks like gcc 5.2.1 does no proper diagnostic at -O1.
What should be done with such issues, are they fixed in the code?

Olaf