[llvm] [ConstantTime][LLVM] Add llvm.ct.select intrinsic with generic SelectionDAG lowering (PR #166702)

[Simon Tatham via llvm-commits]

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@@ -484,6 +484,7 @@ namespace {
     SDValue visitCTTZ_ZERO_UNDEF(SDNode *N);
     SDValue visitCTPOP(SDNode *N);
     SDValue visitSELECT(SDNode *N);
+    SDValue visitCTSELECT(SDNode *N);
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statham-arm wrote:

I hate to say it, but is it possible that the naming of this node will cause confusion? Two lines above this `visitCTSELECT` I see the existing `visitCTPOP`, which _looks_ very similar, but is totally different – your CT stands for "constant time" but theirs stands for "count".

https://github.com/llvm/llvm-project/pull/166702