[clang] [X86][ByteCode] Allow PSHUFB intrinsics to be used in constexpr #156612 (PR #163148)

[Shafik Yaghmour via cfe-commits]

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@@ -11619,6 +11619,44 @@ static bool evalPackBuiltin(const CallExpr *E, EvalInfo &Info, APValue &Result,
   return true;
 }
 
+static bool evalPshufbBuiltin(EvalInfo &Info, const CallExpr *Call,
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shafik wrote:

It is really a shame we are duplicating code so much. If we find a bug in this implementation, will folks really remember to fix it in both places? @RKSimon @tbaederr 

https://github.com/llvm/llvm-project/pull/163148