[llvm] [GISEL] Fix bugs in G_EXTRACT_SUBVECTOR definition (PR #108848)

[Michael Maitland via llvm-commits]

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@@ -1788,7 +1788,7 @@ void MachineVerifier::verifyPreISelGenericInstruction(const MachineInstr *MI) {
     }
 
     uint64_t SrcMinLen = SrcTy.getElementCount().getKnownMinValue();
-    if (SrcTy.isScalable() && DstTy.isScalable() &&
+    if (SrcTy.isScalable() == DstTy.isScalable() &&
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michaelmaitland wrote:

Let's start out by not allowing it? We could probably change our mind down the line if we go in that direction (opposed to allowing it now and disallowing in the future).

https://github.com/llvm/llvm-project/pull/108848