[llvm] [RISCV][ISel] Remove redundant min/max in saturating truncation (PR #75145)

[Craig Topper via llvm-commits]

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@@ -2328,6 +2328,63 @@ defm : VPatBinaryVL_VV_VX_VI<riscv_uaddsat_vl, "PseudoVSADDU">;
 defm : VPatBinaryVL_VV_VX<riscv_ssubsat_vl, "PseudoVSSUB">;
 defm : VPatBinaryVL_VV_VX<riscv_usubsat_vl, "PseudoVSSUBU">;
 
+// 12.5. Vector Narrowing Fixed-Point Clip Instructions
+multiclass VPatTruncSatClipMaxMinBase<string inst, VTypeInfo vti, VTypeInfo wti,
+  SDPatternOperator op1, int op1_value, SDPatternOperator op2, int op2_value> {
+  let Predicates = !listconcat(GetVTypePredicates<vti>.Predicates,
+                               GetVTypePredicates<wti>.Predicates) in
+  def : Pat<(vti.Vector (riscv_trunc_vector_vl
+    (wti.Vector (op1
+        (wti.Vector (op2
+            (wti.Vector wti.RegClass:$rs1),
+            (wti.Vector (riscv_vmv_v_x_vl (wti.Vector undef), op2_value, (XLenVT srcvalue))),
+            (wti.Vector undef),(wti.Mask V0), VLOpFrag)),
+        (wti.Vector (riscv_vmv_v_x_vl (wti.Vector undef), op1_value, (XLenVT srcvalue))),
+        (wti.Vector undef), (wti.Mask V0), VLOpFrag)),
+    (vti.Mask V0), VLOpFrag)), (!cast<Instruction>(inst#"_WI_"#vti.LMul.MX#"_MASK")
+      (vti.Vector (IMPLICIT_DEF)), wti.RegClass:$rs1, 0,
+      (vti.Mask V0), 0, GPR:$vl, vti.Log2SEW, TA_MA)>;
+}
+
+multiclass VPatTruncSatClipUMin<VTypeInfo vti, VTypeInfo wti, int sminval> {
+  let Predicates = !listconcat(GetVTypePredicates<vti>.Predicates,
+                               GetVTypePredicates<wti>.Predicates) in
+  def : Pat<(vti.Vector (riscv_trunc_vector_vl
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topperc wrote:

I don't understand this pattern? I don't think we can make a VNCLIP from smin+trunc.

https://github.com/llvm/llvm-project/pull/75145