Re: [PATCH, rs6000] correct an erroneous BTM value in the BU_P10_MISC define

[Bill Schmidt via Gcc-patches]

On 9/25/20 6:50 PM, Segher Boessenkool wrote:
On Fri, Sep 25, 2020 at 03:34:49PM -0500, will schmidt wrote:
On Fri, 2020-09-25 at 12:36 -0500, Segher Boessenkool wrote:
No, it cannot.
This is used for pdepd/pextd/cntlzdm/cnttzdm/cfuged, all of which do
need 64-bit registers to do anything sane.

This should really have defined some new builtin class, and I thought
we
could just be tricky and take a massive shortcut.  Bill has been hit
by
this already as well, sigh :-(
Ok.

The usage of that macro seems to be limited to those that you have
referenced.  i.e.

/* Builtins for scalar instructions added in ISA 3.1 (power10).  */
BU_P10_MISC_2 (CFUGED, "cfuged", CONST, cfuged)
BU_P10_MISC_2 (CNTLZDM, "cntlzdm", CONST, cntlzdm)
BU_P10_MISC_2 (CNTTZDM, "cnttzdm", CONST, cnttzdm)
BU_P10_MISC_2 (PDEPD, "pdepd", CONST, pdepd)
BU_P10_MISC_2 (PEXTD, "pextd", CONST, pextd)

So looking at the power7 entries that have the BTM_POWERPC64 entry..

BU_P7_MISC_2 (DIVWE,            "divwe",      CONST,  dive_si)
BU_P7_MISC_2 (DIVWEU,           "divweu",     CONST,  diveu_si)
BU_P7_POWERPC64_MISC_2 (DIVDE,  "divde",      CONST,  dive_di)
BU_P7_POWERPC64_MISC_2 (DIVDEU, "divdeu",     CONST,  diveu_di)

Would it be suitable to rename the P10 macro to
BU_P10_POWERPC64_MISC_2 ?
Yes.  But that requires some more infrastructure I thought...  Maybe not
though?  And we can do that anyway of course, it's not like we do not
have way way way too much there already.

I'd then debate whether to add a unused macro to fill the gap between
BU_P10_MISC_1 and BU_P10_MISC_2
Nah, don't bother, those are just names, the numbers are meaningless :-)

If you've got schemes for a deeper fix, i'd need another hint. :-)
Talk with Bill if this makes things easier for him / harder / no
difference?

What Will has in mind is what I would prefer.  I identified this as a 
naming problem above all else.  The only issue for me is that I nearly 
missed it when converting things to use the new builtin methodology, 
because it wasn't made obvious by the naming.

Thanks,

Bill


Thanks,


Segher