[PATCH] Fix gcc 4 warnings on ia64

[PATCH] Fix gcc 4 warnings on ia64

[Andi Kleen]

I was compiling an IA64 2.6.13rc6 kernel on a machine with gcc 4 
to test something. The compile spew a incredibly large number
of warnings. This patch fixes the most annoying ones from
commonly included makefiles. In these two cases  gcc was complaining
that functions cannot be volatile or const.

There are a lot more warnings left, but they're in individual files.
Most seem to be uninitialized variables because gcc 4 can track
individual structure members for that now. 

Signed-off-by: Andi Kleen <ak@suse.de>

diff -u linux-2.6.13rc6/include/asm-ia64/mmu.h-o linux-2.6.13rc6/include/asm-ia64/mmu.h
diff -u linux-2.6.13rc6/include/asm-ia64/io.h-o linux-2.6.13rc6/include/asm-ia64/io.h
--- linux-2.6.13rc6/include/asm-ia64/io.h-o	2005-06-17 21:48:29.000000000 +0200
+++ linux-2.6.13rc6/include/asm-ia64/io.h	2005-08-16 17:37:56.539836121 +0200
@@ -120,7 +120,7 @@
 	ia64_mfa();
 }
 
-static inline const unsigned long
+static inline unsigned long
 __ia64_get_io_port_base (void)
 {
 	extern unsigned long ia64_iobase;
diff -u linux-2.6.13rc6/include/asm-ia64/mmu_context.h-o linux-2.6.13rc6/include/asm-ia64/mmu_context.h
--- linux-2.6.13rc6/include/asm-ia64/mmu_context.h-o	2005-08-16 17:33:16.000000000 +0200
+++ linux-2.6.13rc6/include/asm-ia64/mmu_context.h	2005-08-16 17:45:14.310318038 +0200
@@ -62,7 +62,7 @@
 	}
 }
 
-static inline mm_context_t
+static inline unsigned long
 get_mmu_context (struct mm_struct *mm)
 {
 	unsigned long flags;

Re: [PATCH] Fix gcc 4 warnings on ia64

[Peter Chubb]

>>>>> "Andi" = Andi Kleen <ak@suse.de> writes:

Andi> I was compiling an IA64 2.6.13rc6 kernel on a machine with gcc 4
Andi> to test something. The compile spew a incredibly large number of
Andi> warnings. This patch fixes the most annoying ones from commonly
Andi> included makefiles. In these two cases gcc was complaining that
Andi> functions cannot be volatile or const.

You actually need the const attribute on __ia64_get_io_port_base ---
see the thread at
http://www.gelato.unsw.edu.au/archives/linux-ia64/0507/14658.html 

--
Dr Peter Chubb  http://www.gelato.unsw.edu.au  peterc AT gelato.unsw.edu.au
The technical we do immediately,  the political takes *forever*

Re: [PATCH] Fix gcc 4 warnings on ia64

[Andi Kleen]

On Wed, Aug 17, 2005 at 09:04:24AM +1000, Peter Chubb wrote:
> >>>>> "Andi" = Andi Kleen <ak@suse.de> writes:
> 
> Andi> I was compiling an IA64 2.6.13rc6 kernel on a machine with gcc 4
> Andi> to test something. The compile spew a incredibly large number of
> Andi> warnings. This patch fixes the most annoying ones from commonly
> Andi> included makefiles. In these two cases gcc was complaining that
> Andi> functions cannot be volatile or const.
> 
> You actually need the const attribute on __ia64_get_io_port_base ---
> see the thread at
> http://www.gelato.unsw.edu.au/archives/linux-ia64/0507/14658.html 

Ian is wrong here. const never did the same thing as __attribute__((const))

And for an inline __attribute__((const)) is a nop because the compiler
always looks at the code inside the inline and decides based 
on that if the return value is constant or not. 

-Andi

RE: [PATCH] Fix gcc 4 warnings on ia64

[Luck, Tony]

> You actually need the const attribute on __ia64_get_io_port_base

cscope didn't show any users of this function ... so I thought
perhaps the callers were in some macros that concatenated
strings with ## to make the name, but I couldn't see any.

So I tried the big hammer and just deleted the function
entirely to see what would complain, but nothing did (for
compile with defconfig and tiger_defconfig).

So unless something very, very, very subtle is happening
here, I'd say the fix would be to delete this function
altogether.  Rumours of better/worse code with/without
the "const" modifier look to be unfounded.

Hint: we also store ia64_iobase in ar.k0 ... so perhaps this
function has been obsolete for a while?

-Tony

Re: [PATCH] Fix gcc 4 warnings on ia64

[Andi Kleen]

On Tue, Aug 16, 2005 at 05:05:42PM -0700, Luck, Tony wrote:
> 
> > You actually need the const attribute on __ia64_get_io_port_base
> 
> cscope didn't show any users of this function ... so I thought
> perhaps the callers were in some macros that concatenated
> strings with ## to make the name, but I couldn't see any.

You also need to fix the other function which had a bogus volatile.

BTW I bet the rationale in mmu.h for the volatile is bogus.

-Andi

Re: [PATCH] Fix gcc 4 warnings on ia64

[david mosberger]

On 8/16/05, Andi Kleen <ak@suse.de> wrote:

> And for an inline __attribute__((const)) is a nop because the compiler
> always looks at the code inside the inline and decides based
> on that if the return value is constant or not.

Not if the function contains an "asm", which is what used to be there.
 It later got changed to reading a global, so I agree that the
__attribute_const__ is no longer necessary.

  --david
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