[llvm-branch-commits] [llvm] DAG: Skip poison elements in BUILD_VECTOR computeKnownBits (PR #213326)

[Simon Pilgrim via llvm-branch-commits]

================
@@ -3468,6 +3471,10 @@ KnownBits SelectionDAG::computeKnownBits(SDValue Op, const APInt &DemandedElts,
       if (Known.isUnknown())
         break;
     }
+
+    // If every demanded element was poison, we have nothing known.
----------------
RKSimon wrote:

```suggestion
    // If every demanded element was poison, we have know nothing.
```

https://github.com/llvm/llvm-project/pull/213326