Re: [PATCH 7/7] RISC-V: add zbb support to string functions

[Conor Dooley <conor@kernel.org>]

On Fri, Nov 25, 2022 at 06:02:12PM +0100, Christoph Müllner wrote:
> On Fri, Nov 25, 2022 at 5:39 PM Conor Dooley <conor@kernel.org> wrote:
> >
> > On Fri, Nov 25, 2022 at 05:35:39PM +0100, Christoph Müllner wrote:
> > > On Fri, Nov 25, 2022 at 4:28 PM Andrew Jones <ajones@ventanamicro.com> wrote:
> >
> > > > /*
> > > >  * Each sub-list is sorted alphabetically.
> > > >  */
> > > > #define S_EXTENSIONS                                                    \
> > > >         __RISCV_ISA_EXT_DATA(sscofpmf, RISCV_ISA_EXT_SSCOFPMF),         \
> > > >         __RISCV_ISA_EXT_DATA(sstc, RISCV_ISA_EXT_SSTC),                 \
> > > >         __RISCV_ISA_EXT_DATA(svinval, RISCV_ISA_EXT_SVINVAL),           \
> > > >         __RISCV_ISA_EXT_DATA(svpbmt, RISCV_ISA_EXT_SVPBMT),
> > > >
> > > > #define Zi_EXTENSIONS                                                   \
> > > >         __RISCV_ISA_EXT_DATA(zicbom, RISCV_ISA_EXT_ZICBOM),             \
> > > >         __RISCV_ISA_EXT_DATA(zihintpause, RISCV_ISA_EXT_ZIHINTPAUSE),
> > > >
> > > > #define Zb_EXTENSIONS                                                   \
> > > >         __RISCV_ISA_EXT_DATA(zbb, RISCV_ISA_EXT_ZICBOM),                \
> > > >
> > > > static struct riscv_isa_ext_data isa_ext_arr[] = {
> > > >         Zi_EXTENSIONS
> > > >         Zb_EXTENSIONS
> > > >         S_EXTENSIONS
> > > >         __RISCV_ISA_EXT_DATA("", RISCV_ISA_EXT_MAX),
> > > > };
> > >
> > > It might be worth to look how Binutils are grouping them:
> > >   https://sourceware.org/git/?p=binutils-gdb.git;a=blob;f=bfd/elfxx-riscv.c#l1261
> > >
> > > They also group extensions together but use the following groups:
> > >
> > > const struct riscv_supported_ext *riscv_all_supported_ext[] =
> > > {
> > >   riscv_supported_std_ext,
> > >   riscv_supported_std_z_ext,
> > >   riscv_supported_std_s_ext,
> > >   riscv_supported_std_zxm_ext,
> > >   riscv_supported_vendor_x_ext,
> > >   NULL
> > > };
> >
> > I think in this case, Drew's differentiation between Zi & Zb is an
> > improvement :)
> 
> 
> That might be the case, but it also brings up the following questions:
> Where to put Zf* extensions (between Zi and Zb)?

I don't think that differs either way?

> Where to put Zk* and Zv* (after Zb*)?

Ditto?

> Adding a subgroup for each Z{N}* extension might result in many small
> groups with little benefit.

If it prevents another one of these ordering episodes, I think it's
worth doing! If a "group" only has one element it could alternatively be
added directly also.

Also neat, you got your mailer sorted :)


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