[llvm] [LoopVectorize] Generate wide active lane masks (PR #147535)

[David Sherwood via llvm-commits]

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@@ -614,7 +615,9 @@ Value *VPInstruction::generate(VPTransformState &State) {
                                Name);
 
     auto *Int1Ty = Type::getInt1Ty(Builder.getContext());
-    auto *PredTy = VectorType::get(Int1Ty, State.VF);
+    auto PredTy = VectorType::get(
+        Int1Ty, State.VF * cast<ConstantInt>(getOperand(2)->getLiveInIRValue())
+                               ->getZExtValue());
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david-arm wrote:

I think that given we're now potentially generating a different mask we should update the cost for VPInstruction::ActiveLaneMask in VPInstruction::computeCost if using a wider mask. Again, it's not going to make much difference because the wider mask is generated after the cost model anyway, but good to have it for completeness.

https://github.com/llvm/llvm-project/pull/147535