[llvm] [LV][EVL] Support icmp/fcmp instruction with EVL-vectorization (PR #108533)

[Mel Chen via llvm-commits]

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@@ -1406,6 +1406,30 @@ InstructionCost VPWidenRecipe::computeCost(ElementCount VF,
 void VPWidenEVLRecipe::execute(VPTransformState &State) {
   unsigned Opcode = getOpcode();
   // TODO: Support other opcodes
+  if (Opcode == Instruction::ICmp || Opcode == Instruction::FCmp) {
+    Value *Op1 = State.get(getOperand(0), 0);
+    Value *Op2 = State.get(getOperand(1), 0);
+    auto &Ctx = State.Builder.getContext();
+    Value *Pred = MetadataAsValue::get(
+        Ctx, MDString::get(Ctx, CmpInst::getPredicateName(getPredicate())));
+
+    IRBuilderBase &BuilderIR = State.Builder;
+    VectorBuilder Builder(BuilderIR);
+
+    Value *Mask = BuilderIR.CreateVectorSplat(State.VF, BuilderIR.getTrue());
+    Builder.setMask(Mask).setEVL(State.get(getEVL(), /*NeedsScalar=*/true));
+    VectorType *RetType = VectorType::get(Type::getInt1Ty(Ctx), State.VF);
+    Value *VPInst = Builder.createVectorInstruction(Opcode, RetType,
+                                                    {Op1, Op2, Pred}, "vp.op");
+    if (auto *VecOp = dyn_cast<CastInst>(VPInst))
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Mel-Chen wrote:

Why createVectorInstruction may return CastInst if Opcode is ICmp/FCmp?

https://github.com/llvm/llvm-project/pull/108533