Re: [PATCH 2/4] osdep: Un-inline qemu_thread_jit_execute/write

[Philippe Mathieu-Daudé]

On 15/2/22 14:09, Akihiko Odaki wrote:
> On Tue, Feb 15, 2022 at 9:06 PM Philippe Mathieu-Daudé <f4bug@amsat.org> wrote:
> > qemu_thread_jit_execute() and qemu_thread_jit_write() call
> > pthread_jit_write_protect_np() which is declared in "pthread.h".
> > Since we don't want all C files to preprocess unused headers,
> > avoid adding yet another header here and move the function
> > definitions to osdep.c, un-inlining them.
> >
> > Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> > ---
> >   include/qemu/osdep.h | 17 ++---------------
> >   util/osdep.c         | 20 ++++++++++++++++++++
> >   2 files changed, 22 insertions(+), 15 deletions(-)
> >
> > diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
> > index 1e7a002339..785884728b 100644
> > --- a/include/qemu/osdep.h
> > +++ b/include/qemu/osdep.h
> > @@ -773,21 +773,8 @@ size_t qemu_get_host_physmem(void);
> >    * Toggle write/execute on the pages marked MAP_JIT
> >    * for the current thread.
> >    */
> > -#if defined(MAC_OS_VERSION_11_0) && \
> > -    MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_VERSION_11_0
> > -static inline void qemu_thread_jit_execute(void)
> > -{
> > -    pthread_jit_write_protect_np(true);
> > -}
> > -
> > -static inline void qemu_thread_jit_write(void)
> > -{
> > -    pthread_jit_write_protect_np(false);
> > -}
> > -#else
> > -static inline void qemu_thread_jit_write(void) {}
> > -static inline void qemu_thread_jit_execute(void) {}
> > -#endif
> > +void qemu_thread_jit_execute(void);
> > +void qemu_thread_jit_write(void);
> >
> >   /**
> >    * Platforms which do not support system() return ENOSYS
> > diff --git a/util/osdep.c b/util/osdep.c
> > index 42a0a4986a..b228a53612 100644
> > --- a/util/osdep.c
> > +++ b/util/osdep.c
> > @@ -124,6 +124,26 @@ int qemu_mprotect_none(void *addr, size_t size)
> >   #endif
> >   }
> >
> > +static void qemu_pthread_jit_write_protect(bool enabled)
> > +{
> > +#if defined(MAC_OS_VERSION_11_0) \
> > +        && MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_VERSION_11_0
> > +    if (__builtin_available(macOS 11.0, *)) {
> > +        pthread_jit_write_protect_np(enabled);
> > +    }
> > +#endif
> > +}
> > +
> > +void qemu_thread_jit_execute(void)
> > +{
> > +    qemu_pthread_jit_write_protect(true);
> > +}
> > +
> > +void qemu_thread_jit_write(void)
> > +{
> > +    qemu_pthread_jit_write_protect(false);
> > +}
> > +
> >   #ifndef _WIN32
> >
> >   static int fcntl_op_setlk = -1;
> > --
> > 2.34.1
>
> Is this for compile-time reduction? If so, it would be nice if you
> provide some numbers. It should have some explanation of the advantage
> otherwise.

No, no number, but when using GCC on Monterey, the C files not including
"pthread.h" complain qemu_pthread_jit_write_protect() is not declared,
although not using qemu_thread_jit_execute(). I'll check why GCC is not
eliding unused inlined code.