[LLVMdev] Multiclass patterns

[Bill Wendling]

On Tue, Feb 10, 2009 at 8:27 AM, Villmow, Micah <Micah.Villmow at amd.com> wrote:
> Bill,
>  Sorry if I wasn't clear enough. I wasn't referring to multiclass's that
> define other classes, but with using patterns inside of a multiclass to
> reduce redundant code.
> For example:
> multiclass IntSubtract<SDNode node>
> {
>    def _i8 : Pat<(sub GPRI8:$src0, GPRI8:$src1),
>               (ADD_i8 GPRI8:$src0, (NEGATE_i8 GPRI8:$src1))>;
>    def _i32 : Pat<(sub GPRI32:$src0, GPRI32:$src1),
>               (ADD_i32 GPRI32:$src0, (NEGATE_i32 GPRI32:$src1))>;
> }
>
> or something similar.
> I just want to write the pattern once and then have it apply to multiple
> register types, i.e. a generic pattern rule for many different register
> classes.
>
Please look at the documentation for "multiclass" and "defm". In the
X86InstrSSE.td file, we have this, which looks very similar to what
you have above.

let Constraints = "$src1 = $dst" in {
multiclass basic_sse1_fp_binop_rm<bits<8> opc, string OpcodeStr,
                                  SDNode OpNode, Intrinsic F32Int,
                                  bit Commutable = 0> {
  // Scalar operation, reg+reg.
  def SSrr : SSI<opc, MRMSrcReg, (outs FR32:$dst), (ins FR32:$src1, FR32:$src2),
                 !strconcat(OpcodeStr, "ss\t{$src2, $dst|$dst, $src2}"),
                 [(set FR32:$dst, (OpNode FR32:$src1, FR32:$src2))]> {
    let isCommutable = Commutable;
  }

  // Scalar operation, reg+mem.
  def SSrm : SSI<opc, MRMSrcMem, (outs FR32:$dst),
                                 (ins FR32:$src1, f32mem:$src2),
                 !strconcat(OpcodeStr, "ss\t{$src2, $dst|$dst, $src2}"),
                 [(set FR32:$dst, (OpNode FR32:$src1, (load addr:$src2)))]>;

  // etc.
}
}

// Arithmetic instructions
defm ADD : basic_sse1_fp_binop_rm<0x58, "add", fadd, int_x86_sse_add_ss, 1>;

-bw