On Tue, 2022-05-17 at 23:15 -0400, Michael Meissner wrote:
> On Fri, May 13, 2022 at 01:20:30PM -0500, will schmidt wrote:
> > On Fri, 2022-05-13 at 12:17 -0400, Michael Meissner wrote:
> > >
> > >
<snip>
> > > gcc/
> > > PR target/103109
> > > * config/rs6000/rs6000.md (su_int32): New code attribute.
> > > (<u>mul<mode><dmode>3): Convert from define_expand to
> > > define_insn_and_split.
> > > (maddld<mode>4): Add generator function.
> >
> > -(define_insn "*maddld<mode>4"
> > +(define_insn "maddld<mode>4"
> >
> > Is the removal of the "*" considering adding generator? (Thats
> > terminology that I'm not immediately familiar with).
>
> Yes. If you have a pattern:
>
> (define_insn "foosi2"
> [(set (match_operand:SI 0 "register_operand" "=r")
> (foo:SI (match_operand:SI 1 "register_operand" "r")))]
> ""
> "foo %0,%1")
>
> It creates a 'gen_foosi2' function that has 2 arguments, and it makes
> the insn
> listed.
>
> It then has support for insn recognition and output.
>
> If the pattern starts with a '*', there is no 'gen_foosi2' function
> created,
> but the insn recognitiion and output are still done.
>
> In practice, you typically use the '*' names for patterns that are
> used as the
> targets of combination, or separate insns for different machines.
>
> Here is the verbage from rtl.texi:
>
> These names serve one of two purposes. The first is to indicate that
> the
> instruction performs a certain standard job for the RTL-generation
> pass of the compiler, such as a move, an addition, or a conditional
> jump. The second is to help the target generate certain target-
> specific
> operations, such as when implementing target-specific intrinsic
> functions.
>
> It is better to prefix target-specific names with the name of the
> target, to avoid any clash with current or future standard names.
>
> The absence of a name is indicated by writing an empty string
> where the name should go. Nameless instruction patterns are never
> used for generating RTL code, but they may permit several simpler
> insns
> to be combined later on.
>
> For the purpose of debugging the compiler, you may also specify a
> name beginning with the @samp{*} character. Such a name is used only
> for identifying the instruction in RTL dumps; it is equivalent to
> having
> a nameless pattern for all other purposes. Names beginning with the
> @samp{*} character are not required to be unique.
Thanks for the explanation. :-)
-Will
