Re: [PATCH] math-emu/setcc: avoid gcc extension

Randy Dunlap
2007-01-07T21:08:48Z

On Sun, 7 Jan 2007 19:58:45 +0000 Christoph Hellwig wrote:

> On Sun, Jan 07, 2007 at 11:19:00AM -0800, Randy Dunlap wrote:
> > On Sun, 7 Jan 2007 20:12:42 +0100 Segher Boessenkool wrote:
> >
> > > There's an extra tab in that last line. Could you also
> > > please fix the indenting (use a tab, not spaces) -- I know
> > > it was there originally, but since there are only a few
> > > lines in that file like that... :-)
> >
> > how's this one?
> > ---
> > From: Randy Dunlap <randy.dunlap@oracle.com>
> >
> > setcc() in math-emu is written as a gcc extension statement expression
> > macro that returns a value. However, it's not used that way and it's
> > not needed like that, so just make it a do-while non-extension macro
> > so that we don't use an extension when it's not needed.
> >
> > Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
> > ---
> > arch/i386/math-emu/status_w.h | 5 +++--
> >
> > ---
> > arch/i386/math-emu/status_w.h | 7 ++++---
> > 1 file changed, 4 insertions(+), 3 deletions(-)
> >
> > --- linux-2620-rc2.orig/arch/i386/math-emu/status_w.h
> > +++ linux-2620-rc2/arch/i386/math-emu/status_w.h
> > @@ -48,9 +48,10 @@
> >
> > #define status_word() \
> > ((partial_status & ~SW_Top & 0xffff) | ((top << SW_Top_Shift) & SW_Top))
> > -#define setcc(cc) ({ \
> > - partial_status &= ~(SW_C0|SW_C1|SW_C2|SW_C3); \
> > - partial_status |= (cc) & (SW_C0|SW_C1|SW_C2|SW_C3); })
> > +#define setcc(cc) do { \
> > + partial_status &= ~(SW_C0|SW_C1|SW_C2|SW_C3); \
> > + partial_status |= (cc) & (SW_C0|SW_C1|SW_C2|SW_C3); \
> > +} while (0)
>
> Is there any reason you this shouldn't be an inline function?

That would be OK in theory, so I just tried it.

I don't get the same object files produced with an inline function
(for arch/i386/math-emu/fpu_etc.o), so I don't feel that it's quite
as safe without digging deeping into the .o file and its changes.

The 3 other .o files that use setcc() were the same when using
the inline patch version.

---
From: Randy Dunlap <randy.dunlap@oracle.com>

setcc() in math-emu is written as a gcc extension statement expression
macro that returns a value. However, it's not used that way and it's
not needed like that, so just make it a do-while non-extension macro
so that we don't use an extension when it's not needed.

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
---
arch/i386/math-emu/status_w.h | 5 +++--

---
arch/i386/math-emu/status_w.h | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

--- linux-2620-rc2.orig/arch/i386/math-emu/status_w.h
+++ linux-2620-rc2/arch/i386/math-emu/status_w.h
@@ -48,9 +48,11 @@

#define status_word() \
((partial_status & ~SW_Top & 0xffff) | ((top << SW_Top_Shift) & SW_Top))
-#define setcc(cc) ({ \
- partial_status &= ~(SW_C0|SW_C1|SW_C2|SW_C3); \
- partial_status |= (cc) & (SW_C0|SW_C1|SW_C2|SW_C3); })
+static inline void setcc(int cc)
+{
+ partial_status &= ~(SW_C0|SW_C1|SW_C2|SW_C3);
+ partial_status |= (cc) & (SW_C0|SW_C1|SW_C2|SW_C3);
+}

#ifdef PECULIAR_486
/* Default, this conveys no information, but an 80486 does it. */