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

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``````````bash
git-clang-format --diff origin/main HEAD --extensions cpp,h -- llvm/include/llvm/CodeGen/ISDOpcodes.h llvm/include/llvm/CodeGen/SelectionDAG.h llvm/include/llvm/CodeGen/SelectionDAGNodes.h llvm/include/llvm/CodeGen/TargetLowering.h llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp llvm/lib/CodeGen/SelectionDAG/LegalizeFloatTypes.cpp llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.h llvm/lib/CodeGen/SelectionDAG/LegalizeTypesGeneric.cpp llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp --diff_from_common_commit
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``````````diff
diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
index 468f2b26a..739e5a064 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -4244,23 +4244,29 @@ bool SelectionDAGLegalize::ExpandNode(SDNode *Node) {
       EVT ScalarVT = VT.getScalarType();
       for (unsigned Idx = 0; Idx < NumElements; ++Idx) {
         SDValue IdxVal = DAG.getConstant(Idx, dl, MVT::i64);
-        SDValue TVal = DAG.getNode(ISD::EXTRACT_VECTOR_ELT, dl, ScalarVT, Tmp2, IdxVal);
-        SDValue FVal = DAG.getNode(ISD::EXTRACT_VECTOR_ELT, dl, ScalarVT, Tmp3, IdxVal);
-        Elements.push_back(DAG.getCTSelect(dl, ScalarVT, Tmp1, TVal, FVal, Node->getFlags()));
+        SDValue TVal =
+            DAG.getNode(ISD::EXTRACT_VECTOR_ELT, dl, ScalarVT, Tmp2, IdxVal);
+        SDValue FVal =
+            DAG.getNode(ISD::EXTRACT_VECTOR_ELT, dl, ScalarVT, Tmp3, IdxVal);
+        Elements.push_back(
+            DAG.getCTSelect(dl, ScalarVT, Tmp1, TVal, FVal, Node->getFlags()));
       }
       Tmp1 = DAG.getBuildVector(VT, dl, Elements);
     } else if (VT.isFloatingPoint()) {
       EVT IntegerVT = EVT::getIntegerVT(*DAG.getContext(), VT.getSizeInBits());
       Tmp2 = DAG.getBitcast(IntegerVT, Tmp2);
       Tmp3 = DAG.getBitcast(IntegerVT, Tmp3);
-      Tmp1 = DAG.getBitcast(VT, DAG.getCTSelect(dl, IntegerVT, Tmp1, Tmp2, Tmp3, Node->getFlags()));
+      Tmp1 = DAG.getBitcast(VT, DAG.getCTSelect(dl, IntegerVT, Tmp1, Tmp2, Tmp3,
+                                                Node->getFlags()));
     } else {
       assert(VT.isInteger());
       EVT HalfVT = VT.getHalfSizedIntegerVT(*DAG.getContext());
       auto [Tmp2Lo, Tmp2Hi] = DAG.SplitScalar(Tmp2, dl, HalfVT, HalfVT);
       auto [Tmp3Lo, Tmp3Hi] = DAG.SplitScalar(Tmp3, dl, HalfVT, HalfVT);
-      SDValue ResLo = DAG.getCTSelect(dl, HalfVT, Tmp1, Tmp2Lo, Tmp3Lo, Node->getFlags());
-      SDValue ResHi = DAG.getCTSelect(dl, HalfVT, Tmp1, Tmp2Hi, Tmp3Hi, Node->getFlags());
+      SDValue ResLo =
+          DAG.getCTSelect(dl, HalfVT, Tmp1, Tmp2Lo, Tmp3Lo, Node->getFlags());
+      SDValue ResHi =
+          DAG.getCTSelect(dl, HalfVT, Tmp1, Tmp2Hi, Tmp3Hi, Node->getFlags());
       Tmp1 = DAG.getNode(ISD::BUILD_PAIR, dl, VT, ResLo, ResHi);
       Tmp1->setFlags(Node->getFlags());
     }

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