[clang] [llvm] [HLSL] Implement `WaveReadLaneAt` intrinsic (PR #111010)

[Chris B via cfe-commits]

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@@ -1956,6 +1956,26 @@ bool SemaHLSL::CheckBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
       return true;
     break;
   }
+  case Builtin::BI__builtin_hlsl_wave_read_lane_at: {
+    if (SemaRef.checkArgCount(TheCall, 2))
+      return true;
+
+    // Ensure index parameter type can be interpreted as a uint
+    ExprResult Index = TheCall->getArg(1);
+    QualType ArgTyIndex = Index.get()->getType();
+    if (!ArgTyIndex->hasIntegerRepresentation()) {
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llvm-beanz wrote:

I don't think this is the correct check. This will return `true` for vectors of integers. I think we really want `isIntegerType()`.

https://github.com/llvm/llvm-project/pull/111010