[RISCV][ISel] remove redundant min/max followed by a trunc.

Fixes llvm#73424. If the range created by a min and max is precisely the range of trunc target, the min/max could be removed.
sun-jacobi · Dec 29, 2023 · af443b0 · af443b0
1 parent a22c8ef
commit af443b0
Showing 1 changed file with 54 additions and 0 deletions.
diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfoVVLPatterns.td b/llvm/lib/Target/RISCV/RISCVInstrInfoVVLPatterns.td
@@ -1625,6 +1625,60 @@ multiclass VPatBinaryFPWVL_VV_VF_WV_WF_RM<SDNode vop, SDNode vop_w, string instr
   }
 }
 
+
+multiclass VPatTruncSplatMaxMinIdentityBase<VTypeInfo vti, VTypeInfo wti,
+  SDPatternOperator vop1, int vid1, SDPatternOperator vop2, int vid2> {
+  let Predicates = !listconcat(GetVTypePredicates<vti>.Predicates,
+                               GetVTypePredicates<wti>.Predicates) in
+  def : Pat<(vti.Vector (riscv_trunc_vector_vl
+    (wti.Vector (vop1
+        (wti.Vector (vop2
+            (wti.Vector wti.RegClass:$rs1),
+            (wti.Vector (riscv_vmv_v_x_vl (wti.Vector undef), vid2, (XLenVT srcvalue))),
+            (wti.Vector undef),(wti.Mask V0), VLOpFrag)),
+        (wti.Vector (riscv_vmv_v_x_vl (wti.Vector undef), vid1, (XLenVT srcvalue))),
+        (wti.Vector undef), (wti.Mask V0), VLOpFrag)),
+    (vti.Mask V0), VLOpFrag)),
+    (!cast<Instruction>("PseudoVNSRL_WI_"#vti.LMul.MX#"_MASK")
+      (vti.Vector (IMPLICIT_DEF)), wti.RegClass:$rs1, 0,
+      (vti.Mask V0), GPR:$vl, vti.Log2SEW, TA_MA)>;
+}
+
+multiclass VPatTruncSplatMinIdentityBase<VTypeInfo vti, VTypeInfo wti,
+  SDPatternOperator vop, int vid> {
+  let Predicates = !listconcat(GetVTypePredicates<vti>.Predicates,
+                               GetVTypePredicates<wti>.Predicates) in
+  def : Pat<(vti.Vector (riscv_trunc_vector_vl
+    (wti.Vector (vop
+      (wti.Vector wti.RegClass:$rs1),
+      (wti.Vector (riscv_vmv_v_x_vl (wti.Vector undef), vid, (XLenVT srcvalue))),
+      (wti.Vector undef), (wti.Mask V0), VLOpFrag)),
+    (vti.Mask V0), VLOpFrag)),
+    (!cast<Instruction>("PseudoVNSRL_WI_"#vti.LMul.MX#"_MASK")
+      (vti.Vector (IMPLICIT_DEF)), wti.RegClass:$rs1, 0,
+      (vti.Mask V0), GPR:$vl, vti.Log2SEW, TA_MA)>;
+}
+
+
+multiclass VPatTruncSplatMaxMinIdentity<VTypeInfo vti, VTypeInfo wti> {
+  defvar sew = vti.SEW;
+  defvar umin_id = !sub(!shl(1, sew), 1);
+  defvar umax_id = 0;
+  defvar smin_id = !sub(!shl(1, !sub(sew, 1)), 1);
+  defvar smax_id = !sub(0, !shl(1, !sub(sew, 1)));
+
+  defm : VPatTruncSplatMaxMinIdentityBase<vti, wti, riscv_umax_vl, umax_id, riscv_umin_vl, umin_id>;
+  defm : VPatTruncSplatMaxMinIdentityBase<vti, wti, riscv_umin_vl, umin_id, riscv_umax_vl, umax_id>;
+  defm : VPatTruncSplatMaxMinIdentityBase<vti, wti, riscv_smin_vl, smin_id, riscv_smax_vl, smax_id>;
+  defm : VPatTruncSplatMaxMinIdentityBase<vti, wti, riscv_smax_vl, smax_id, riscv_smin_vl, smin_id>;
+
+  defm : VPatTruncSplatMinIdentityBase<vti, wti, riscv_umin_vl, umin_id>;
+
+}
+
+foreach vtiToWti = AllWidenableIntVectors in
+  defm : VPatTruncSplatMaxMinIdentity<vtiToWti.Vti, vtiToWti.Wti>;
+
 multiclass VPatNarrowShiftSplatExt_WX<SDNode op, PatFrags extop, string instruction_name> {
   foreach vtiToWti = AllWidenableIntVectors in {
     defvar vti = vtiToWti.Vti;