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

[Farzon Lotfi via llvm-commits]

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@@ -2653,6 +2653,22 @@ bool SPIRVInstructionSelector::selectIntrinsic(Register ResVReg,
         .addUse(GR.getSPIRVTypeID(ResType))
         .addUse(GR.getOrCreateConstInt(3, I, IntTy, TII));
   }
+  case Intrinsic::spv_wave_read_lane_at: {
+    assert(I.getNumOperands() == 4);
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farzonl wrote:

Put this block in a select function. It makes it easier to see all the various case statements when scrolling through the intrinsic selector.

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