llvm-project/llvm/lib/Target/PowerPC/README_P9.txt

//===- README_P9.txt - Notes for improving Power9 code gen ----------------===//

TODO: Instructions Need Implement Instrinstics or Map to LLVM IR

Altivec:
- Vector Compare Not Equal (Zero):
  vcmpneb(.) vcmpneh(.) vcmpnew(.)
  vcmpnezb(.) vcmpnezh(.) vcmpnezw(.)
  . Same as other VCMP*, use VCMP/VCMPo form (support intrinsic)

- Vector Extract Unsigned: vextractub vextractuh vextractuw vextractd
  . Don't use llvm extractelement because they have different semantics
  . Use instrinstics:
    (set v2i64:$vD, (int_ppc_altivec_vextractub v16i8:$vA, imm:$UIMM))
    (set v2i64:$vD, (int_ppc_altivec_vextractuh v8i16:$vA, imm:$UIMM))
    (set v2i64:$vD, (int_ppc_altivec_vextractuw v4i32:$vA, imm:$UIMM))
    (set v2i64:$vD, (int_ppc_altivec_vextractd  v2i64:$vA, imm:$UIMM))

- Vector Extract Unsigned Byte Left/Right-Indexed:
  vextublx vextubrx vextuhlx vextuhrx vextuwlx vextuwrx
  . Use instrinstics:
    // Left-Indexed
    (set i64:$rD, (int_ppc_altivec_vextublx i64:$rA, v16i8:$vB))
    (set i64:$rD, (int_ppc_altivec_vextuhlx i64:$rA, v8i16:$vB))
    (set i64:$rD, (int_ppc_altivec_vextuwlx i64:$rA, v4i32:$vB))

    // Right-Indexed
    (set i64:$rD, (int_ppc_altivec_vextubrx i64:$rA, v16i8:$vB))
    (set i64:$rD, (int_ppc_altivec_vextuhrx i64:$rA, v8i16:$vB))
    (set i64:$rD, (int_ppc_altivec_vextuwrx i64:$rA, v4i32:$vB))

- Vector Insert Element Instructions: vinsertb vinsertd vinserth vinsertw
    (set v16i8:$vD, (int_ppc_altivec_vinsertb v16i8:$vA, imm:$UIMM))
    (set v8i16:$vD, (int_ppc_altivec_vinsertd v8i16:$vA, imm:$UIMM))
    (set v4i32:$vD, (int_ppc_altivec_vinserth v4i32:$vA, imm:$UIMM))
    (set v2i64:$vD, (int_ppc_altivec_vinsertw v2i64:$vA, imm:$UIMM))

- Vector Count Leading/Trailing Zero LSB. Result is placed into GPR[rD]:
  vclzlsbb vctzlsbb
  . Use intrinsic:
    (set i64:$rD, (int_ppc_altivec_vclzlsbb v16i8:$vB))
    (set i64:$rD, (int_ppc_altivec_vctzlsbb v16i8:$vB))

- Vector Count Trailing Zeros: vctzb vctzh vctzw vctzd
  . Map to llvm cttz
    (set v16i8:$vD, (cttz v16i8:$vB))     // vctzb
    (set v8i16:$vD, (cttz v8i16:$vB))     // vctzh
    (set v4i32:$vD, (cttz v4i32:$vB))     // vctzw
    (set v2i64:$vD, (cttz v2i64:$vB))     // vctzd

- Vector Extend Sign: vextsb2w vextsh2w vextsb2d vextsh2d vextsw2d
  . vextsb2w:
    (set v4i32:$vD, (sext v4i8:$vB))

    // PowerISA_V3.0:
    do i = 0 to 3
       VR[VRT].word[i] ← EXTS32(VR[VRB].word[i].byte[3])
    end

  . vextsh2w:
    (set v4i32:$vD, (sext v4i16:$vB))

    // PowerISA_V3.0:
    do i = 0 to 3
       VR[VRT].word[i] ← EXTS32(VR[VRB].word[i].hword[1])
    end

  . vextsb2d
    (set v2i64:$vD, (sext v2i8:$vB))

    // PowerISA_V3.0:
    do i = 0 to 1
       VR[VRT].dword[i] ← EXTS64(VR[VRB].dword[i].byte[7])
    end

  . vextsh2d
    (set v2i64:$vD, (sext v2i16:$vB))

    // PowerISA_V3.0:
    do i = 0 to 1
       VR[VRT].dword[i] ← EXTS64(VR[VRB].dword[i].hword[3])
    end

  . vextsw2d
    (set v2i64:$vD, (sext v2i32:$vB))

    // PowerISA_V3.0:
    do i = 0 to 1
       VR[VRT].dword[i] ← EXTS64(VR[VRB].dword[i].word[1])
    end

- Vector Integer Negate: vnegw vnegd
  . Map to llvm ineg
    (set v4i32:$rT, (ineg v4i32:$rA))       // vnegw
    (set v2i64:$rT, (ineg v2i64:$rA))       // vnegd

- Vector Parity Byte: vprtybw vprtybd vprtybq
  . Use intrinsic:
    (set v4i32:$rD, (int_ppc_altivec_vprtybw v4i32:$vB))
    (set v2i64:$rD, (int_ppc_altivec_vprtybd v2i64:$vB))
    (set v1i128:$rD, (int_ppc_altivec_vprtybq v1i128:$vB))

- Vector (Bit) Permute (Right-indexed):
  . vbpermd: Same as "vbpermq", use VX1_Int_Ty2:
    VX1_Int_Ty2<1484, "vbpermd", int_ppc_altivec_vbpermd, v2i64, v2i64>;

  . vpermr: use VA1a_Int_Ty3
    VA1a_Int_Ty3<59, "vpermr", int_ppc_altivec_vpermr, v16i8, v16i8, v16i8>;

- Vector Rotate Left Mask/Mask-Insert: vrlwnm vrlwmi vrldnm vrldmi
  . Use intrinsic:
    VX1_Int_Ty<389, "vrlwnm", int_ppc_altivec_vrlwnm, v4i32>;
    VX1_Int_Ty<133, "vrlwmi", int_ppc_altivec_vrlwmi, v4i32>;
    VX1_Int_Ty<453, "vrldnm", int_ppc_altivec_vrldnm, v2i64>;
    VX1_Int_Ty<197, "vrldmi", int_ppc_altivec_vrldmi, v2i64>;

- Vector Shift Left/Right: vslv vsrv
  . Use intrinsic, don't map to llvm shl and lshr, because they have different
    semantics, e.g. vslv:

      do i = 0 to 15
         sh ← VR[VRB].byte[i].bit[5:7]
         VR[VRT].byte[i] ← src.byte[i:i+1].bit[sh:sh+7]
      end

    VR[VRT].byte[i] is composed of 2 bytes from src.byte[i:i+1]

  . VX1_Int_Ty<1860, "vslv", int_ppc_altivec_vslv, v16i8>;
    VX1_Int_Ty<1796, "vsrv", int_ppc_altivec_vsrv, v16i8>;

- Vector Multiply-by-10 (& Write Carry) Unsigned Quadword:
  vmul10uq vmul10cuq
  . Use intrinsic:
    VX1_Int_Ty<513, "vmul10uq",   int_ppc_altivec_vmul10uq,  v1i128>;
    VX1_Int_Ty<  1, "vmul10cuq",  int_ppc_altivec_vmul10cuq, v1i128>;

- Vector Multiply-by-10 Extended (& Write Carry) Unsigned Quadword:
  vmul10euq vmul10ecuq
  . Use intrinsic:
    VX1_Int_Ty<577, "vmul10euq",  int_ppc_altivec_vmul10euq, v1i128>;
    VX1_Int_Ty< 65, "vmul10ecuq", int_ppc_altivec_vmul10ecuq, v1i128>;

- Decimal Convert From/to National/Zoned/Signed-QWord:
  bcdcfn. bcdcfz. bcdctn. bcdctz. bcdcfsq. bcdctsq.
  . Use instrinstics:
    (set v1i128:$vD, (int_ppc_altivec_bcdcfno  v1i128:$vB, i1:$PS))
    (set v1i128:$vD, (int_ppc_altivec_bcdcfzo  v1i128:$vB, i1:$PS))
    (set v1i128:$vD, (int_ppc_altivec_bcdctno  v1i128:$vB))
    (set v1i128:$vD, (int_ppc_altivec_bcdctzo  v1i128:$vB, i1:$PS))
    (set v1i128:$vD, (int_ppc_altivec_bcdcfsqo v1i128:$vB, i1:$PS))
    (set v1i128:$vD, (int_ppc_altivec_bcdctsqo v1i128:$vB))

- Decimal Copy-Sign/Set-Sign: bcdcpsgn. bcdsetsgn.
  . Use instrinstics:
    (set v1i128:$vD, (int_ppc_altivec_bcdcpsgno v1i128:$vA, v1i128:$vB))
    (set v1i128:$vD, (int_ppc_altivec_bcdsetsgno v1i128:$vB, i1:$PS))

- Decimal Shift/Unsigned-Shift/Shift-and-Round: bcds. bcdus. bcdsr.
  . Use instrinstics:
    (set v1i128:$vD, (int_ppc_altivec_bcdso  v1i128:$vA, v1i128:$vB, i1:$PS))
    (set v1i128:$vD, (int_ppc_altivec_bcduso v1i128:$vA, v1i128:$vB))
    (set v1i128:$vD, (int_ppc_altivec_bcdsro v1i128:$vA, v1i128:$vB, i1:$PS))

  . Note! Their VA is accessed only 1 byte, i.e. VA.byte[7]

- Decimal (Unsigned) Truncate: bcdtrunc. bcdutrunc.
  . Use instrinstics:
    (set v1i128:$vD, (int_ppc_altivec_bcdso  v1i128:$vA, v1i128:$vB, i1:$PS))
    (set v1i128:$vD, (int_ppc_altivec_bcduso v1i128:$vA, v1i128:$vB))

  . Note! Their VA is accessed only 2 byte, i.e. VA.hword[3] (VA.bit[48:63])

VSX:
- QP Copy Sign: xscpsgnqp
  . Similar to xscpsgndp
  . (set f128:$vT, (fcopysign f128:$vB, f128:$vA)

- QP Absolute/Negative-Absolute/Negate: xsabsqp xsnabsqp xsnegqp
  . Similar to xsabsdp/xsnabsdp/xsnegdp
  . (set f128:$vT, (fabs f128:$vB))             // xsabsqp
    (set f128:$vT, (fneg (fabs f128:$vB)))      // xsnabsqp
    (set f128:$vT, (fneg f128:$vB))             // xsnegqp

- QP Add/Divide/Multiply/Subtract/Square-Root:
  xsaddqp xsdivqp xsmulqp xssubqp xssqrtqp
  . Similar to xsadddp
  . isCommutable = 1
    (set f128:$vT, (fadd f128:$vA, f128:$vB))   // xsaddqp
    (set f128:$vT, (fmul f128:$vA, f128:$vB))   // xsmulqp

  . isCommutable = 0
    (set f128:$vT, (fdiv f128:$vA, f128:$vB))   // xsdivqp
    (set f128:$vT, (fsub f128:$vA, f128:$vB))   // xssubqp
    (set f128:$vT, (fsqrt f128:$vB)))           // xssqrtqp

- Round to Odd of QP Add/Divide/Multiply/Subtract/Square-Root:
  xsaddqpo xsdivqpo xsmulqpo xssubqpo xssqrtqpo
  . Similar to xsrsqrtedp??
      def XSRSQRTEDP : XX2Form<60, 74,
                               (outs vsfrc:$XT), (ins vsfrc:$XB),
                               "xsrsqrtedp $XT, $XB", IIC_VecFP,
                               [(set f64:$XT, (PPCfrsqrte f64:$XB))]>;

  . Define DAG Node in PPCInstrInfo.td:
    def PPCfaddrto: SDNode<"PPCISD::FADDRTO", SDTFPBinOp, []>;
    def PPCfdivrto: SDNode<"PPCISD::FDIVRTO", SDTFPBinOp, []>;
    def PPCfmulrto: SDNode<"PPCISD::FMULRTO", SDTFPBinOp, []>;
    def PPCfsubrto: SDNode<"PPCISD::FSUBRTO", SDTFPBinOp, []>;
    def PPCfsqrtrto: SDNode<"PPCISD::FSQRTRTO", SDTFPUnaryOp, []>;

    DAG patterns of each instruction (PPCInstrVSX.td):
    . isCommutable = 1
      (set f128:$vT, (PPCfaddrto f128:$vA, f128:$vB))   // xsaddqpo
      (set f128:$vT, (PPCfmulrto f128:$vA, f128:$vB))   // xsmulqpo

    . isCommutable = 0
      (set f128:$vT, (PPCfdivrto f128:$vA, f128:$vB))   // xsdivqpo
      (set f128:$vT, (PPCfsubrto f128:$vA, f128:$vB))   // xssubqpo
      (set f128:$vT, (PPCfsqrtrto f128:$vB))            // xssqrtqpo

- QP (Negative) Multiply-{Add/Subtract}: xsmaddqp xsmsubqp xsnmaddqp xsnmsubqp
  . Ref: xsmaddadp/xsmsubadp/xsnmaddadp/xsnmsubadp

  . isCommutable = 1
    // xsmaddqp
    [(set f128:$vT, (fma f128:$vA, f128:$vB, f128:$vTi))]>,
    RegConstraint<"$vTi = $vT">, NoEncode<"$vTi">,
    AltVSXFMARel;

    // xsmsubqp
    [(set f128:$vT, (fma f128:$vA, f128:$vB, (fneg f128:$vTi)))]>,
    RegConstraint<"$vTi = $vT">, NoEncode<"$vTi">,
    AltVSXFMARel;

    // xsnmaddqp
    [(set f128:$vT, (fneg (fma f128:$vA, f128:$vB, f128:$vTi)))]>,
    RegConstraint<"$vTi = $vT">, NoEncode<"$vTi">,
    AltVSXFMARel;

    // xsnmsubqp
    [(set f128:$vT, (fneg (fma f128:$vA, f128:$vB, (fneg f128:$vTi))))]>,
    RegConstraint<"$vTi = $vT">, NoEncode<"$vTi">,
    AltVSXFMARel;

- Round to Odd of QP (Negative) Multiply-{Add/Subtract}:
  xsmaddqpo xsmsubqpo xsnmaddqpo xsnmsubqpo
  . Similar to xsrsqrtedp??

  . Define DAG Node in PPCInstrInfo.td:
    def PPCfmarto: SDNode<"PPCISD::FMARTO", SDTFPTernaryOp, []>;

    It looks like we only need to define "PPCfmarto" for these instructions,
    because according to PowerISA_V3.0, these instructions perform RTO on
    fma's result:
        xsmaddqp(o)
        v      ← bfp_MULTIPLY_ADD(src1, src3, src2)
        rnd    ← bfp_ROUND_TO_BFP128(RO, FPSCR.RN, v)
        result ← bfp_CONVERT_TO_BFP128(rnd)

        xsmsubqp(o)
        v      ← bfp_MULTIPLY_ADD(src1, src3, bfp_NEGATE(src2))
        rnd    ← bfp_ROUND_TO_BFP128(RO, FPSCR.RN, v)
        result ← bfp_CONVERT_TO_BFP128(rnd)

        xsnmaddqp(o)
        v      ← bfp_MULTIPLY_ADD(src1,src3,src2)
        rnd    ← bfp_NEGATE(bfp_ROUND_TO_BFP128(RO, FPSCR.RN, v))
        result ← bfp_CONVERT_TO_BFP128(rnd)

        xsnmsubqp(o)
        v      ← bfp_MULTIPLY_ADD(src1, src3, bfp_NEGATE(src2))
        rnd    ← bfp_NEGATE(bfp_ROUND_TO_BFP128(RO, FPSCR.RN, v))
        result ← bfp_CONVERT_TO_BFP128(rnd)

    DAG patterns of each instruction (PPCInstrVSX.td):
    . isCommutable = 1
      // xsmaddqpo
      [(set f128:$vT, (PPCfmarto f128:$vA, f128:$vB, f128:$vTi))]>,
      RegConstraint<"$vTi = $vT">, NoEncode<"$vTi">,
      AltVSXFMARel;

      // xsmsubqpo
      [(set f128:$vT, (PPCfmarto f128:$vA, f128:$vB, (fneg f128:$vTi)))]>,
      RegConstraint<"$vTi = $vT">, NoEncode<"$vTi">,
      AltVSXFMARel;

      // xsnmaddqpo
      [(set f128:$vT, (fneg (PPCfmarto f128:$vA, f128:$vB, f128:$vTi)))]>,
      RegConstraint<"$vTi = $vT">, NoEncode<"$vTi">,
      AltVSXFMARel;

      // xsnmsubqpo
      [(set f128:$vT, (fneg (PPCfmarto f128:$vA, f128:$vB, (fneg f128:$vTi))))]>,
      RegConstraint<"$vTi = $vT">, NoEncode<"$vTi">,
      AltVSXFMARel;

- QP Compare Ordered/Unordered: xscmpoqp xscmpuqp
  . ref: XSCMPUDP
      def XSCMPUDP : XX3Form_1<60, 35,
                               (outs crrc:$crD), (ins vsfrc:$XA, vsfrc:$XB),
                               "xscmpudp $crD, $XA, $XB", IIC_FPCompare, []>;

  . No SDAG, intrinsic, builtin are required??
    Or llvm fcmp order/unorder compare??

- DP/QP Compare Exponents: xscmpexpdp xscmpexpqp
  . No SDAG, intrinsic, builtin are required?

- DP Compare ==, >=, >, !=: xscmpeqdp xscmpgedp xscmpgtdp xscmpnedp
  . I checked existing instruction "XSCMPUDP". They are different in target
    register. "XSCMPUDP" write to CR field, xscmp*dp write to VSX register

  . Use instrinsic:
    (set i128:$XT, (int_ppc_vsx_xscmpeqdp f64:$XA, f64:$XB))
    (set i128:$XT, (int_ppc_vsx_xscmpgedp f64:$XA, f64:$XB))
    (set i128:$XT, (int_ppc_vsx_xscmpgtdp f64:$XA, f64:$XB))
    (set i128:$XT, (int_ppc_vsx_xscmpnedp f64:$XA, f64:$XB))

- Vector Compare Not Equal: xvcmpnedp xvcmpnedp. xvcmpnesp xvcmpnesp.
  . Similar to xvcmpeqdp:
      defm XVCMPEQDP : XX3Form_Rcr<60, 99,
                                 "xvcmpeqdp", "$XT, $XA, $XB", IIC_VecFPCompare,
                                 int_ppc_vsx_xvcmpeqdp, v2i64, v2f64>;

  . So we should use "XX3Form_Rcr" to implement instrinsic

- Convert DP -> QP: xscvdpqp
  . Similar to XSCVDPSP:
      def XSCVDPSP : XX2Form<60, 265,
                          (outs vsfrc:$XT), (ins vsfrc:$XB),
                          "xscvdpsp $XT, $XB", IIC_VecFP, []>;
  . So, No SDAG, intrinsic, builtin are required??

- Round & Convert QP -> DP (dword[1] is set to zero): xscvqpdp xscvqpdpo
  . Similar to XSCVDPSP
  . No SDAG, intrinsic, builtin are required??

- Truncate & Convert QP -> (Un)Signed (D)Word (dword[1] is set to zero):
  xscvqpsdz xscvqpswz xscvqpudz xscvqpuwz
  . According to PowerISA_V3.0, these are similar to "XSCVDPSXDS", "XSCVDPSXWS",
    "XSCVDPUXDS", "XSCVDPUXWS"

  . DAG patterns:
    (set f128:$XT, (PPCfctidz f128:$XB))    // xscvqpsdz
    (set f128:$XT, (PPCfctiwz f128:$XB))    // xscvqpswz
    (set f128:$XT, (PPCfctiduz f128:$XB))   // xscvqpudz
    (set f128:$XT, (PPCfctiwuz f128:$XB))   // xscvqpuwz

- Convert (Un)Signed DWord -> QP: xscvsdqp xscvudqp
  . Similar to XSCVSXDSP
  . (set f128:$XT, (PPCfcfids f64:$XB))     // xscvsdqp
    (set f128:$XT, (PPCfcfidus f64:$XB))    // xscvudqp

- (Round &) Convert DP <-> HP: xscvdphp xscvhpdp
  . Similar to XSCVDPSP
  . No SDAG, intrinsic, builtin are required??

- Vector HP -> SP: xvcvhpsp xvcvsphp
  . Similar to XVCVDPSP:
      def XVCVDPSP : XX2Form<60, 393,
                          (outs vsrc:$XT), (ins vsrc:$XB),
                          "xvcvdpsp $XT, $XB", IIC_VecFP, []>;
  . No SDAG, intrinsic, builtin are required??

- Round to Quad-Precision Integer: xsrqpi xsrqpix
  . These are combination of "XSRDPI", "XSRDPIC", "XSRDPIM", .., because you
    need to assign rounding mode in instruction
  . Provide builtin?
    (set f128:$vT, (int_ppc_vsx_xsrqpi f128:$vB))
    (set f128:$vT, (int_ppc_vsx_xsrqpix f128:$vB))

- Round Quad-Precision to Double-Extended Precision (fp80): xsrqpxp
  . Provide builtin?
    (set f128:$vT, (int_ppc_vsx_xsrqpxp f128:$vB))

Fixed Point Facility:

- Exploit cmprb and cmpeqb (perhaps for something like
  isalpha/isdigit/isupper/islower and isspace respectivelly). This can
  perhaps be done through a builtin.

- Provide testing for cnttz[dw]
- Insert Exponent DP/QP: xsiexpdp xsiexpqp
  . Use intrinsic?
  . xsiexpdp:
    // Note: rA and rB are the unsigned integer value.
    (set f128:$XT, (int_ppc_vsx_xsiexpdp i64:$rA, i64:$rB))

  . xsiexpqp:
    (set f128:$vT, (int_ppc_vsx_xsiexpqp f128:$vA, f64:$vB))

- Extract Exponent/Significand DP/QP: xsxexpdp xsxsigdp xsxexpqp xsxsigqp
  . Use intrinsic?
  . (set i64:$rT, (int_ppc_vsx_xsxexpdp f64$XB))    // xsxexpdp
    (set i64:$rT, (int_ppc_vsx_xsxsigdp f64$XB))    // xsxsigdp
    (set f128:$vT, (int_ppc_vsx_xsxexpqp f128$vB))  // xsxexpqp
    (set f128:$vT, (int_ppc_vsx_xsxsigqp f128$vB))  // xsxsigqp

- Vector Insert Word: xxinsertw
  - Useful for inserting f32/i32 elements into vectors (the element to be
    inserted needs to be prepared)
  . Note: llvm has insertelem in "Vector Operations"
    ; yields <n x <ty>>
    <result> = insertelement <n x <ty>> <val>, <ty> <elt>, <ty2> <idx>

    But how to map to it??
    [(set v1f128:$XT, (insertelement v1f128:$XTi, f128:$XB, i4:$UIMM))]>,
    RegConstraint<"$XTi = $XT">, NoEncode<"$XTi">,

  . Or use intrinsic?
    (set v1f128:$XT, (int_ppc_vsx_xxinsertw v1f128:$XTi, f128:$XB, i4:$UIMM))

- Vector Extract Unsigned Word: xxextractuw
  - Not useful for extraction of f32 from v4f32 (the current pattern is better -
    shift->convert)
  - It is useful for (uint_to_fp (vector_extract v4i32, N))
  - Unfortunately, it can't be used for (sint_to_fp (vector_extract v4i32, N))
  . Note: llvm has extractelement in "Vector Operations"
    ; yields <ty>
    <result> = extractelement <n x <ty>> <val>, <ty2> <idx>

    How to map to it??
    [(set f128:$XT, (extractelement v1f128:$XB, i4:$UIMM))]

  . Or use intrinsic?
    (set f128:$XT, (int_ppc_vsx_xxextractuw v1f128:$XB, i4:$UIMM))

- Vector Insert Exponent DP/SP: xviexpdp xviexpsp
  . Use intrinsic
    (set v2f64:$XT, (int_ppc_vsx_xviexpdp v2f64:$XA, v2f64:$XB))
    (set v4f32:$XT, (int_ppc_vsx_xviexpsp v4f32:$XA, v4f32:$XB))

- Vector Extract Exponent/Significand DP/SP: xvxexpdp xvxexpsp xvxsigdp xvxsigsp
  . Use intrinsic
    (set v2f64:$XT, (int_ppc_vsx_xvxexpdp v2f64:$XB))
    (set v4f32:$XT, (int_ppc_vsx_xvxexpsp v4f32:$XB))
    (set v2f64:$XT, (int_ppc_vsx_xvxsigdp v2f64:$XB))
    (set v4f32:$XT, (int_ppc_vsx_xvxsigsp v4f32:$XB))

- Test Data Class SP/DP/QP: xststdcsp xststdcdp xststdcqp
  . No SDAG, intrinsic, builtin are required?
    Because it seems that we have no way to map BF field?

    Instruction Form: [PO T XO B XO BX TX]
    Asm: xststd* BF,XB,DCMX

    BF is an index to CR register field.

- Vector Test Data Class SP/DP: xvtstdcsp xvtstdcdp
  . Use intrinsic
    (set v4f32:$XT, (int_ppc_vsx_xvtstdcsp v4f32:$XB, i7:$DCMX))
    (set v2f64:$XT, (int_ppc_vsx_xvtstdcdp v2f64:$XB, i7:$DCMX))

- Maximum/Minimum Type-C/Type-J DP: xsmaxcdp xsmaxjdp xsmincdp xsminjdp
  . PowerISA_V3.0:
    "xsmaxcdp can be used to implement the C/C++/Java conditional operation
     (x>y)?x:y for single-precision and double-precision arguments."

    Note! c type and j type have different behavior when:
    1. Either input is NaN
    2. Both input are +-Infinity, +-Zero

  . dtype map to llvm fmaxnum/fminnum
    jtype use intrinsic

  . xsmaxcdp xsmincdp
    (set f64:$XT, (fmaxnum f64:$XA, f64:$XB))
    (set f64:$XT, (fminnum f64:$XA, f64:$XB))

  . xsmaxjdp xsminjdp
    (set f64:$XT, (int_ppc_vsx_xsmaxjdp f64:$XA, f64:$XB))
    (set f64:$XT, (int_ppc_vsx_xsminjdp f64:$XA, f64:$XB))

- Vector Byte-Reverse H/W/D/Q Word: xxbrh xxbrw xxbrd xxbrq
  . Use intrinsic
    (set v8i16:$XT, (int_ppc_vsx_xxbrh v8i16:$XB))
    (set v4i32:$XT, (int_ppc_vsx_xxbrw v4i32:$XB))
    (set v2i64:$XT, (int_ppc_vsx_xxbrd v2i64:$XB))
    (set v1i128:$XT, (int_ppc_vsx_xxbrq v1i128:$XB))

- Vector Permute: xxperm xxpermr
  . I have checked "PPCxxswapd" in PPCInstrVSX.td, but they are different
  . Use intrinsic
    (set v16i8:$XT, (int_ppc_vsx_xxperm v16i8:$XA, v16i8:$XB))
    (set v16i8:$XT, (int_ppc_vsx_xxpermr v16i8:$XA, v16i8:$XB))

- Vector Splat Immediate Byte: xxspltib
  . Similar to XXSPLTW:
      def XXSPLTW : XX2Form_2<60, 164,
                           (outs vsrc:$XT), (ins vsrc:$XB, u2imm:$UIM),
                           "xxspltw $XT, $XB, $UIM", IIC_VecPerm, []>;

  . No SDAG, intrinsic, builtin are required?

- Load/Store Vector: lxv stxv
  . Has likely SDAG match:
    (set v?:$XT, (load ix16addr:$src))
    (set v?:$XT, (store ix16addr:$dst))

  . Need define ix16addr in PPCInstrInfo.td
    ix16addr: 16-byte aligned, see "def memrix16" in PPCInstrInfo.td

- Load/Store Vector Indexed: lxvx stxvx
  . Has likely SDAG match:
    (set v?:$XT, (load xoaddr:$src))
    (set v?:$XT, (store xoaddr:$dst))

- Load/Store DWord: lxsd stxsd
  . Similar to lxsdx/stxsdx:
    def LXSDX : XX1Form<31, 588,
                        (outs vsfrc:$XT), (ins memrr:$src),
                        "lxsdx $XT, $src", IIC_LdStLFD,
                        [(set f64:$XT, (load xoaddr:$src))]>;

  . (set f64:$XT, (load iaddrX4:$src))
    (set f64:$XT, (store iaddrX4:$dst))

- Load/Store SP, with conversion from/to DP: lxssp stxssp
  . Similar to lxsspx/stxsspx:
    def LXSSPX : XX1Form<31, 524, (outs vssrc:$XT), (ins memrr:$src),
                         "lxsspx $XT, $src", IIC_LdStLFD,
                         [(set f32:$XT, (load xoaddr:$src))]>;

  . (set f32:$XT, (load iaddrX4:$src))
    (set f32:$XT, (store iaddrX4:$dst))

- Load as Integer Byte/Halfword & Zero Indexed: lxsibzx lxsihzx
  . Similar to lxsiwzx:
    def LXSIWZX : XX1Form<31, 12, (outs vsfrc:$XT), (ins memrr:$src),
                          "lxsiwzx $XT, $src", IIC_LdStLFD,
                          [(set f64:$XT, (PPClfiwzx xoaddr:$src))]>;

  . (set f64:$XT, (PPClfiwzx xoaddr:$src))

- Store as Integer Byte/Halfword Indexed: stxsibx stxsihx
  . Similar to stxsiwx:
    def STXSIWX : XX1Form<31, 140, (outs), (ins vsfrc:$XT, memrr:$dst),
                          "stxsiwx $XT, $dst", IIC_LdStSTFD,
                          [(PPCstfiwx f64:$XT, xoaddr:$dst)]>;

  . (PPCstfiwx f64:$XT, xoaddr:$dst)

- Load Vector Halfword*8/Byte*16 Indexed: lxvh8x lxvb16x
  . Similar to lxvd2x/lxvw4x:
    def LXVD2X : XX1Form<31, 844,
                         (outs vsrc:$XT), (ins memrr:$src),
                         "lxvd2x $XT, $src", IIC_LdStLFD,
                         [(set v2f64:$XT, (int_ppc_vsx_lxvd2x xoaddr:$src))]>;

  . (set v8i16:$XT, (int_ppc_vsx_lxvh8x xoaddr:$src))
    (set v16i8:$XT, (int_ppc_vsx_lxvb16x xoaddr:$src))

- Store Vector Halfword*8/Byte*16 Indexed: stxvh8x stxvb16x
  . Similar to stxvd2x/stxvw4x:
    def STXVD2X : XX1Form<31, 972,
                         (outs), (ins vsrc:$XT, memrr:$dst),
                         "stxvd2x $XT, $dst", IIC_LdStSTFD,
                         [(store v2f64:$XT, xoaddr:$dst)]>;

  . (store v8i16:$XT, xoaddr:$dst)
    (store v16i8:$XT, xoaddr:$dst)

- Load/Store Vector (Left-justified) with Length: lxvl lxvll stxvl stxvll
  . Likely needs an intrinsic
  . (set v?:$XT, (int_ppc_vsx_lxvl xoaddr:$src))
    (set v?:$XT, (int_ppc_vsx_lxvll xoaddr:$src))

  . (int_ppc_vsx_stxvl xoaddr:$dst))
    (int_ppc_vsx_stxvll xoaddr:$dst))

- Load Vector Word & Splat Indexed: lxvwsx
  . Likely needs an intrinsic
  . (set v?:$XT, (int_ppc_vsx_lxvwsx xoaddr:$src))

Atomic operations (l[dw]at, st[dw]at):
- Provide custom lowering for common atomic operations to use these
  instructions with the correct Function Code
- Ensure the operands are in the correct register (i.e. RT+1, RT+2)
- Provide builtins since not all FC's necessarily have an existing LLVM
  atomic operation

Load Doubleword Monitored (ldmx):
- Investigate whether there are any uses for this. It seems to be related to
  Garbage Collection so it isn't likely to be all that useful for most
  languages we deal with.

Move to CR from XER Extended (mcrxrx):
- Is there a use for this in LLVM?

Fixed Point Facility:

- Copy-Paste Facility: copy copy_first cp_abort paste paste. paste_last
  . Use instrinstics:
    (int_ppc_copy_first i32:$rA, i32:$rB)
    (int_ppc_copy i32:$rA, i32:$rB)

    (int_ppc_paste i32:$rA, i32:$rB)
    (int_ppc_paste_last i32:$rA, i32:$rB)

    (int_cp_abort)

- Message Synchronize: msgsync
- SLB*: slbieg slbsync
- stop
  . No instrinstics