[llvm] [AArch64] Fixup destructive floating-point precision conversions (PR #118788)

[via llvm-commits]

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@@ -9296,33 +9279,18 @@ multiclass sve_float_dot_indexed<bit bf, bits<2> opc, ZPRRegOp src1_ty,
   def : SVE_4_Op_Imm_Pat<nxv4f32, op, nxv4f32, InVT, InVT, i32, VectorIndexS32b_timm, !cast<Instruction>(NAME)>;
 }
 
-class sve_bfloat_convert<bit N, string asm>
-: I<(outs ZPR16:$Zd), (ins ZPR16:$_Zd, PPR3bAny:$Pg, ZPR32:$Zn),
-  asm, "\t$Zd, $Pg/m, $Zn", "", []>, Sched<[]> {
-  bits<5> Zd;
-  bits<3> Pg;
-  bits<5> Zn;
-  let Inst{31-25} = 0b0110010;
-  let Inst{24}    = N;
-  let Inst{23-13} = 0b10001010101;
-  let Inst{12-10} = Pg;
-  let Inst{9-5}   = Zn;
-  let Inst{4-0}   = Zd;
+multiclass sve_bfloat_convert<string asm, SDPatternOperator op, SDPatternOperator ir_op> {
+  def NAME : sve_fp_2op_p_zd<0b1001010, asm, ZPR32, ZPR16, ElementSizeS>;
 
-  let Constraints = "$Zd = $_Zd";
-  let DestructiveInstType = DestructiveOther;
-  let ElementSize = ElementSizeS;
-  let hasSideEffects = 0;
-  let mayRaiseFPException = 1;
+  def : SVE_3_Op_Pat<nxv8bf16, op, nxv8bf16, nxv4i1, nxv4f32, !cast<Instruction>(NAME)>;
+  def : SVE_1_Op_Passthru_Round_Pat<nxv4bf16, ir_op, nxv4i1, nxv4f32, !cast<Instruction>(NAME)>;
+  def : SVE_1_Op_Passthru_Round_Pat<nxv2bf16, ir_op, nxv2i1, nxv2f32, !cast<Instruction>(NAME)>;
 }
 
-multiclass sve_bfloat_convert<bit N, string asm, SDPatternOperator op,
-                              SDPatternOperator ir_op = null_frag> {
-  def NAME : sve_bfloat_convert<N, asm>;
+multiclass sve_bfloat_convert_top<string asm,  SDPatternOperator op> {
+  def NAME : sve2_fp_convert_precision<0b1010, 0b1, asm, ZPR16, ZPR32>;
 
   def : SVE_3_Op_Pat<nxv8bf16, op, nxv8bf16, nxv4i1, nxv4f32, !cast<Instruction>(NAME)>;
-  def : SVE_1_Op_Passthru_Round_Pat<nxv4bf16, ir_op, nxv4i1, nxv4f32, !cast<Instruction>(NAME)>;
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SpencerAbson wrote:

When `bfcvtnt` used `sve_bfloat_convert` it passed `null_frag` to `ir_op`, because this argument was only relevant for `bfcvt`. Since this class is only used for `bfcvtnt`, there was no need to keep things that were only relevant for `bfcvt`.

https://github.com/llvm/llvm-project/pull/118788