[clang] [CIR] Implement folder for VecShuffleDynamicOp (PR #142315)

[Henrich Lauko via cfe-commits]

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@@ -1597,9 +1598,9 @@ OpFoldResult cir::VecShuffleDynamicOp::fold(FoldAdaptor adaptor) {
     elements.reserve(numElements);
 
     const uint64_t maskBits = llvm::NextPowerOf2(numElements - 1) - 1;
-    for (uint64_t i = 0; i < numElements; i++) {
-      cir::IntAttr idxAttr = mlir::cast<cir::IntAttr>(indicesElts[i]);
-      uint64_t idxValue = idxAttr.getUInt();
+    for (const mlir::APInt &idxAttr :
+         indicesElts.getAsValueRange<cir::IntAttr, mlir::APInt>()) {
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xlauko wrote:

or maybe use just `getAsRange` ie.:

```
for (const auto &idxAttr : indicesElts.getAsRange<cir::IntAttr>()) {
```

and original `uint64_t idxValue = idxAttr.getUInt();`

https://github.com/llvm/llvm-project/pull/142315