Re: [PATCH v4 0/2] Replaced locks with lock guard macros

[Eric Blake]

> > > You can test locally by building with clang (llvm) instead of gcc:
> > >
> > >    ./configure --cc=clang
> >
> > Using --cc=clang is causing the following error in several different places:
> > qemu/target/ppc/translate.c:1894:18: error: result of comparison
> > 'target_ulong' (aka 'unsigned int') <= 4294967295
> > is always true [-Werror,-Wtautological-type-limit-compare]
> >          if (mask <= 0xffffffffu) {
> >              ~~~~ ^  ~~~~~~~~~~~
> >
> > these errors don't come up when building with gcc. Any idea how to fix
> > this? Or should I just suppress it?
>
> I'm of the opinion that it should be suppressed.
>
> This is the *correct* test for ppc64, and the warning for ppc32 is simply
> because target_ulong == uint32_t.  True is the correct result for ppc32.
>
> We simply want the compiler to DTRT: simplify this test and remove the else as
> unreachable.

There may be ways to rewrite that expression to avoid triggering the 
warning on a 32-bit platform.  Untested, but does this help:

if (sizeof(mask) > 4 && mask <= 0xffffffffu) {

--
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org