Re: help on adding new insns like min/max

[Andrew Pinski <apinski at apple dot com>]

Actually I messed up the definition of max:

#define max(a,b) ({__typeof__(a) a1=(a); __typeof__(b) b1 = (b); 
(a1>b1)?a1:b1})

Sorry,
Andrew Pinski


On Monday, Oct 21, 2002, at 18:03 US/Pacific, Ming Ouyang wrote:

> Andrew,
> Thanks for your reply. __typeof__ does make 2 or more min/max in one
> function work, but it can't resolve complicated operands problem yet,
> can you help on that?
> Thanks so much.
>
> Ming
>
>
> --- Andrew Pinski <apinski@apple.com> wrote:
> > try this, using extensions for gcc:
> >
> > #define max(a,b) ({__typeof__(a) a1=(a); __typeof__(b) b1 = (b);
> > (a>b)?a:b})
> >
> > Thanks,
> > Andrew Pinski
> >
> > On Monday, Oct 21, 2002, at 17:34 US/Pacific, Ming Ouyang wrote:
> >
> > > Dale,
> > > I just found that macro doesn't always work well, for any complicated
> > > operands like: max(a, ++b), max(a+b, c), max(a, foo(c)), gcc won't
> > > use max insn for them, it only use max insn for max(a,b).
> > > In addition, if I have more than one maxs/mins, it seems gcc will
> > > not generate max/min for them, could you give me some help on that?
> > > Thanks a lot.
> > >
> > > Ming
> > >
> > > --- Dale Johannesen <dalej@apple.com> wrote:
> > > > On Monday, October 21, 2002, at 04:05  PM, Ming Ouyang wrote:
> > > >
> > > > > I tried my gcc with definition of sminsi3/smaxsi3 and I dumpped
> > > > > all debug info, gcc always treats min as a function call in my
> > > > > test.c.00.rtl through test.c.30.dbr:
> > > > >
> > > > > (call (mem:SI (symbol_ref/v:SI ("smin")) ))
> > > > >
> > > > > I think once gcc found that is a function call, it would not
> > > > > optimize it, am I right?
> > > > > What I should get is something like "(smin: SI ...", is that right?
> > > > > So probably I need to change something other than xxx.md?
> > > > > Thanks.
> > > > If you're using it as a function of course gcc will treat it as
> > > > a function.  It is not one of the standard C functions so gcc does
> > > > not do anything special to it (and is not allowed to, that would
> > > > break standard conformance).  The usual way to get min/max
> > > > functionality
> > > > in C is to put a macro definition in a header file somewhere,
> > > > something
> > > > like
> > > > #define MAX(x,y) ((x>y) ? x : y)
> > > > (watch out for ++ operators, improvement left as an exercise)
> > >
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