[llvm] [SVE] Wide active lane mask (PR #76514)

[via llvm-commits]

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@@ -1202,6 +1202,35 @@ class VPInstruction : public VPRecipeWithIRFlags, public VPValue {
   }
 };
 
+class VPActiveLaneMaskRecipe : public VPRecipeWithIRFlags, public VPValue {
+  const std::string Name;
+  ElementCount MaxLength;
+
+public:
+  VPActiveLaneMaskRecipe(VPValue *IV, VPValue *TC, // ElementCount MaxLength,
+                         DebugLoc DL = {}, const Twine &Name = "")
+      : VPRecipeWithIRFlags(VPDef::VPActiveLaneMaskSC,
+                            std::initializer_list<VPValue *>{IV, TC}, DL),
+        VPValue(this), Name(Name.str()) {} //, MaxLength(MaxLength) {}
+
+  VP_CLASSOF_IMPL(VPDef::VPActiveLaneMaskSC)
+
+  void execute(VPTransformState &State) override;
+
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
+  /// Print the recipe.
+  void print(raw_ostream &O, const Twine &Indent,
+             VPSlotTracker &SlotTracker) const override;
+#endif
+
+  bool onlyFirstLaneUsed(const VPValue *Op) const override {
+    assert(is_contained(operands(), Op) &&
+           "Op must be an operand of the recipe");
+
+    return getOperand(0) == Op;
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CarolineConcatto wrote:

Why we need to check only the first operand?

https://github.com/llvm/llvm-project/pull/76514