On Tue, 2020-06-09 at 17:01 -0700, Carl Love wrote:
> Segher:
>
> So I have been looking at the predicate definitions that I had
> created.
>
> On Fri, 2020-06-05 at 16:28 -0500, Segher Boessenkool wrote:
> > > +;; Return 1 if op is a 32-bit constant signed integer
> > > +(define_predicate "s32bit_cint_operand"
> > > + (and (match_code "const_int")
> > > + (match_test "INTVAL (op) >= -2147483648
> > > + && INTVAL (op) <= 2147483647")))
> >
> > There probably is a nicer way to write this than with big decimal
> > numbers. (I'll not suggest one here because I'll just make a fool
> > of
> > myself with overflow or signed/unsigned etc. :-) )
> >
> > > +;; Return 1 if op is a constant 32-bit signed or unsigned
> > > integer
> > > +(define_predicate "c32bit_cint_operand"
> > > + (and (match_code "const_int")
> > > + (match_test "((INTVAL (op) >> 32) == 0)")))
>
> The more I look at the above two they really are the
> same. Basically,
> it boils down to ... can the value signed or unsigned fit in 32-bits
> or
> not? It seems like both of the above just need to test if the INTVAL
> (op) has any bits above bits 0:31 set. So seems like (INTVAL (op) >>
> 32) == 0) should be sufficient for both predicates, i.e. replace the
> two with a single generic predicate "cint_32bit_operand".
>
> For starters, I tried changing the definition for s32bit_cint_operand
> to:
>
> ; Return 1 if op is a 32-bit constant signed integer
>
> (define_predicate "s32bit_cint_operand"
>
> (and (match_code "const_int")
>
> (match_test "((INTVAL (op) >> 32) == 0)")))
Compare that to the other predicates (config/rs6000/predicates.md)
Those have explicit checks against both ends of the valid range of
values. i.e.
;; Return 1 if op is a signed 5-bit constant integer.
(define_predicate "s5bit_cint_operand"
(and (match_code "const_int")
(match_test "INTVAL (op) >= -16 && INTVAL (op) <= 15")))
>
> Unfortunately it doesn't seem to work for
>
> (define_insn
> "xxspltiw_v4si"
> [(set (match_operand:V4SI 0 "register_operand"
> "=wa")
> (unspec:V4SI [(match_operand:SI 1 "s32bit_cint_operand"
> "n")]
> UNSPEC_XXSPLTIW))]
>
> "TARGET_FUTURE"
>
> "xxspltiw
> %x0,%1"
> [(set_attr "type" "vecsimple")])
>
> I get unrecongized insn. It seems like (INTVAL (op) >> 32) == 0)
> should be true for any 32-bit integer signed or unsigned???
>
> Any thoughts as to why this doesn't work?
>
> >
> > This does not work for negative 32-bit numbers? In GCC the LHS
> > expression is -1 for those... Not sure what it is for the C++11 we
> > now
> > require, but in C11 it is implementation-defined, so not good
> > either.
> >
> > > +;; Return 1 if op is a constant 32-bit floating point value
> > > +(define_predicate "f32bit_const_operand"
> > > + (match_code "const_double"))
> >
> > Either the predicate name is misleading (if you do allow all
> > const_double values), or there should be some test for the alloed
> > values
> > here.
>
> The predicate is used to check for a 32-bit float constant. Looking
> thru the code not sure if const_double is a 64-bit float? I don't
> think
> that is what I want. I want a 32-bit floating point value,
> const_float, const_real? Don't see a a const_float or anything that
> looks like that? Not having much luck to see where const_double gets
> defined to see what other definitions there are.
>
> I am assuming at this point in the compilation process, the constant
> that is passed has type info (signed int, unsigned int, float)
> associated with it from the front end parsing of the source code.
>
> Carl
>
