Re: [Qemu-devel] [PATCH] translate: cleanup gen_intermediate_code_internal

[li guang]

在 2013-04-10三的 11:54 +0200，Paolo Bonzini写道：
> Il 10/04/2013 09:55, li guang ha scritto:
> > 在 2013-04-10三的 09:44 +0200，Paolo Bonzini写道：
> >> Il 10/04/2013 05:30, liguang ha scritto:
> >>> Signed-off-by: liguang <address@hidden>
> >>> ---
> >>>  target-arm/translate.c  |   17 ++++++++---------
> >>>  target-i386/translate.c |   17 ++++++++---------
> >>>  target-mips/translate.c |   16 ++++++++--------
> >>>  3 files changed, 24 insertions(+), 26 deletions(-)
> >>>
> >>> diff --git a/target-arm/translate.c b/target-arm/translate.c
> >>> index 35a21be..c0c080d 100644
> >>> --- a/target-arm/translate.c
> >>> +++ b/target-arm/translate.c
> >>> @@ -9806,11 +9806,10 @@ static inline void 
> >>> gen_intermediate_code_internal(CPUARMState *env,
> >>>      cpu_M0 = tcg_temp_new_i64();
> >>>      next_page_start = (pc_start & TARGET_PAGE_MASK) + TARGET_PAGE_SIZE;
> >>>      lj = -1;
> >>> -    num_insns = 0;
> >>
> >> Nack.  Did you even try to read what I and Wei-Ren Chen were trying to
> >> tell you?
> >>
> > 
> > well, you ask if I tested, and I answer yes,
> > you doubt if this line really could be removed,
> > and I said compiler will not complain this.
> 
> I don't care if the compiler doesn't complain (though I doubt it
> doesn't; are you using --enable-debug?

absolutely yes.

> ).  It is wrong.
> 
> You are removing the initialization of num_insns.  The only instruction
> that modifies it is now "num_insns++".  That is wrong, period.  Even if
> GCC ends up producing code that works, what happens when you access
> uninitialized memory is undefined.
> 
> > what should I do?
> > Isn't it enough?
> > did you read my answer for your comment?
> 
> You didn't reply to this message from Wei-Ren Chen:
> 
> >> I think 'max_insns = tb->cflags & CF_COUNT_MASK;' is enough
> >> to feed compiler.
> > 
> >   num_insns and max_insns are two different variables, right? So this
> > assignment does not do anything with num_insns.
> 
> So yes, I read your answers and no, they were not enough.

OK, I won't change here for next post.
Thanks!