[clang] [Headers][X86] VectorExprEvaluator::VisitCallExpr - allow SSE/AVX2/AVX512 pack intrinsics to be used in constexpr (PR #156003)

[Shafik Yaghmour via cfe-commits]

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@@ -11599,6 +11599,89 @@ static bool handleVectorElementCast(EvalInfo &Info, const FPOptions FPO,
   return false;
 }
 
+enum class PackKind {
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shafik wrote:

Pack is such an overloaded word in C++, can we get something more specific, I don't have a good suggestion, I am going to throw out SSEAVXPackKind as a strawman but please find something better if you can.

https://github.com/llvm/llvm-project/pull/156003