[llvm] [GISEL] G_SPLAT_VECTOR can take a splat that is larger than the vector element (PR #86974)

[Matt Arsenault via llvm-commits]

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@@ -1768,16 +1768,23 @@ void MachineVerifier::verifyPreISelGenericInstruction(const MachineInstr *MI) {
     LLT DstTy = MRI->getType(MI->getOperand(0).getReg());
     LLT SrcTy = MRI->getType(MI->getOperand(1).getReg());
 
-    if (!DstTy.isScalableVector())
+    if (!DstTy.isScalableVector()) {
       report("Destination type must be a scalable vector", MI);
+      break;
+    }
 
-    if (!SrcTy.isScalar())
+    if (!SrcTy.isScalar()) {
       report("Source type must be a scalar", MI);
+      break;
+    }
 
-    if (DstTy.getScalarType() != SrcTy)
-      report("Element type of the destination must be the same type as the "
-             "source type",
+    if (TypeSize::isKnownGT(DstTy.getScalarType().getSizeInBits(),
----------------
arsenm wrote:

```suggestion
    if (TypeSize::isKnownGT(DstTy.getElementType().getSizeInBits(),
```

https://github.com/llvm/llvm-project/pull/86974