[RISCV] Remove pseudos for vwcvt.f.x(u) with rounding mode.

[craig.topper]

Summary

vwcvt.f.x doesn't use rounding mode. The integer value fits in
the mantissa of a 2x larger FP type so no rounding is required.

I've remove the Uses = [FRM] that is also not needed.

I deleted the isel patterns. Alternatively, we could keep them and
drop the rounding mode immediate. The patterns are currently untested
so I chose to delete them. If they become needed in the future, we
can decide then if we should have the patterns or teach the node
creation to use the non-RM form for widening.

This reverts part of D142102.

[luke]

LGTM, looks like gcc also removed their frm operand from vfwcvt.f.x[u] too: https://github.com/nstester/gcc/commit/b65458005dfb38f2efdca52e42f3dbf4760f91bd

llvm/lib/Target/RISCV/RISCVISelLowering.cpp

 //===-- RISCVISelLowering.cpp - RISC-V DAG Lowering Implementation  -------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
#define PseudoVFCVT_RM_CASE_MF8(RMOpc, Opc)                                    \
   PseudoVFCVT_RM_CASE_M8(PseudoVFCVT_RM_X_F_V, PseudoVFCVT_X_F_V)
   PseudoVFCVT_RM_CASE_M8(PseudoVFCVT_RM_XU_F_V, PseudoVFCVT_XU_F_V)
   PseudoVFCVT_RM_CASE_M8(PseudoVFCVT_RM_F_XU_V, PseudoVFCVT_F_XU_V)
   PseudoVFCVT_RM_CASE_M8(PseudoVFCVT_RM_F_X_V, PseudoVFCVT_F_X_V)
 
   // VFWCVT
   PseudoVFCVT_RM_CASE(PseudoVFWCVT_RM_XU_F_V, PseudoVFWCVT_XU_F_V);
   PseudoVFCVT_RM_CASE(PseudoVFWCVT_RM_X_F_V, PseudoVFWCVT_X_F_V);
-  PseudoVFCVT_RM_CASE_MF8(PseudoVFWCVT_RM_F_XU_V, PseudoVFWCVT_F_XU_V);
-  PseudoVFCVT_RM_CASE_MF8(PseudoVFWCVT_RM_F_X_V, PseudoVFWCVT_F_X_V);
 
   // VFNCVT
   PseudoVFCVT_RM_CASE_MF8(PseudoVFNCVT_RM_XU_F_W, PseudoVFNCVT_XU_F_W);
   PseudoVFCVT_RM_CASE_MF8(PseudoVFNCVT_RM_X_F_W, PseudoVFNCVT_X_F_W);
   PseudoVFCVT_RM_CASE(PseudoVFNCVT_RM_F_XU_W, PseudoVFNCVT_F_XU_W);
   PseudoVFCVT_RM_CASE(PseudoVFNCVT_RM_F_X_W, PseudoVFNCVT_F_X_W);
 
   case RISCV::PseudoVFROUND_NOEXCEPT_V_M1_MASK:

llvm/lib/Target/RISCV/RISCVInstrInfoVPseudos.td

foreach m = MxListW in {
     defvar WriteVFWCvtIToFV_MX = !cast<SchedWrite>("WriteVFWCvtIToFV_" # mx);
     defvar ReadVFWCvtIToFV_MX = !cast<SchedRead>("ReadVFWCvtIToFV_" # mx);
 
     defm _V : VPseudoConversion<m.wvrclass, m.vrclass, m, constraint>,
               Sched<[WriteVFWCvtIToFV_MX, ReadVFWCvtIToFV_MX, ReadVMask]>;
   }
 }
 
-multiclass VPseudoVWCVTF_RM_V {
-  defvar constraint = "@earlyclobber $rd";
-  foreach m = MxListW in {
-    defvar mx = m.MX;
-    defvar WriteVFWCvtIToFV_MX = !cast<SchedWrite>("WriteVFWCvtIToFV_" # mx);
-    defvar ReadVFWCvtIToFV_MX = !cast<SchedRead>("ReadVFWCvtIToFV_" # mx);
-
-    defm _V : VPseudoConversionRM<m.wvrclass, m.vrclass, m, constraint>,
-              Sched<[WriteVFWCvtIToFV_MX, ReadVFWCvtIToFV_MX, ReadVMask]>;
-  }
-}
-
 multiclass VPseudoVWCVTD_V {
   defvar constraint = "@earlyclobber $rd";
   foreach m = MxListFW in {
     defvar mx = m.MX;
     defvar WriteVFWCvtFToFV_MX = !cast<SchedWrite>("WriteVFWCvtFToFV_" # mx);
     defvar ReadVFWCvtFToFV_MX = !cast<SchedRead>("ReadVFWCvtFToFV_" # mx);
 
     defm _V : VPseudoConversion<m.wvrclass, m.vrclass, m, constraint>,

 defm PseudoVFWCVT_X_F      : VPseudoVWCVTI_V;
 }
 defm PseudoVFWCVT_RM_XU_F  : VPseudoVWCVTI_RM_V;
 defm PseudoVFWCVT_RM_X_F   : VPseudoVWCVTI_RM_V;
 
 defm PseudoVFWCVT_RTZ_XU_F : VPseudoVWCVTI_V;
 defm PseudoVFWCVT_RTZ_X_F  : VPseudoVWCVTI_V;
 
-let Uses = [FRM] in {
 defm PseudoVFWCVT_F_XU     : VPseudoVWCVTF_V;
 defm PseudoVFWCVT_F_X      : VPseudoVWCVTF_V;
-}
-defm PseudoVFWCVT_RM_F_XU  : VPseudoVWCVTF_RM_V;
-defm PseudoVFWCVT_RM_F_X   : VPseudoVWCVTF_RM_V;
 
 defm PseudoVFWCVT_F_F      : VPseudoVWCVTD_V;
 } // mayRaiseFPException = true
 
 //===----------------------------------------------------------------------===//
 // 13.19. Narrowing Floating-Point/Integer Type-Convert Instructions
 //===----------------------------------------------------------------------===//
 let mayRaiseFPException = true in {

llvm/lib/Target/RISCV/RISCVInstrInfoVVLPatterns.td

def : Pat<(fwti.Vector (vop (ivti.Vector ivti.RegClass:$rs1),
                                 (ivti.Mask V0),
                                 VLOpFrag)),
               (!cast<Instruction>(instruction_name#"_"#ivti.LMul.MX#"_MASK")
                   (fwti.Vector (IMPLICIT_DEF)), ivti.RegClass:$rs1,
                   (ivti.Mask V0), GPR:$vl, ivti.Log2SEW, TA_MA)>;
   }
 }
 
-multiclass VPatWConvertI2FP_RM_VL_V<SDNode vop, string instruction_name> {
-  foreach vtiToWti = AllWidenableIntToFloatVectors in {
-    defvar ivti = vtiToWti.Vti;
-    defvar fwti = vtiToWti.Wti;
-    let Predicates = !listconcat(GetVTypePredicates<ivti>.Predicates,
-                                 GetVTypePredicates<fwti>.Predicates) in
-    def : Pat<(fwti.Vector (vop (ivti.Vector ivti.RegClass:$rs1),
-                                (ivti.Mask V0), (XLenVT timm:$frm),
-                                VLOpFrag)),
-              (!cast<Instruction>(instruction_name#"_"#ivti.LMul.MX#"_MASK")
-                  (fwti.Vector (IMPLICIT_DEF)), ivti.RegClass:$rs1,
-                  (ivti.Mask V0), timm:$frm, GPR:$vl, ivti.Log2SEW, TA_MA)>;
-  }
-}
-
 // Narrowing converting
 
 multiclass VPatNConvertFP2IVL_W<SDPatternOperator vop,
                                 string instruction_name> {
   // Reuse the same list of types used in the widening nodes, but just swap the
   // direction of types around so we're converting from Wti -> Vti
   foreach vtiToWti = AllWidenableIntToFloatVectors in {
     defvar vti = vtiToWti.Vti;

 defm : VPatWConvertFP2I_RM_VL_V<riscv_vfcvt_rm_x_f_vl, "PseudoVFWCVT_RM_X_F_V">;
 
 defm : VPatWConvertFP2IVL_V<any_riscv_vfcvt_rtz_xu_f_vl, "PseudoVFWCVT_RTZ_XU_F_V">;
 defm : VPatWConvertFP2IVL_V<any_riscv_vfcvt_rtz_x_f_vl, "PseudoVFWCVT_RTZ_X_F_V">;
 
 defm : VPatWConvertI2FPVL_V<any_riscv_uint_to_fp_vl, "PseudoVFWCVT_F_XU_V">;
 defm : VPatWConvertI2FPVL_V<any_riscv_sint_to_fp_vl, "PseudoVFWCVT_F_X_V">;
 
-defm : VPatWConvertI2FP_RM_VL_V<riscv_vfcvt_rm_f_xu_vl, "PseudoVFWCVT_RM_F_XU_V">;
-defm : VPatWConvertI2FP_RM_VL_V<riscv_vfcvt_rm_f_x_vl, "PseudoVFWCVT_RM_F_X_V">;
-
 foreach fvtiToFWti = AllWidenableFloatVectors in {
   defvar fvti = fvtiToFWti.Vti;
   defvar fwti = fvtiToFWti.Wti;
   let Predicates = !listconcat(GetVTypePredicates<fvti>.Predicates,
                                GetVTypePredicates<fwti>.Predicates) in
   def : Pat<(fwti.Vector (any_riscv_fpextend_vl
                              (fvti.Vector fvti.RegClass:$rs1),
                              (fvti.Mask V0),