[clang] [clang] VectorExprEvaluator::VisitCallExpr - add constant folding for X86 pslldqi/psrldqi intrinsics (PR #157403)

[Simon Pilgrim via cfe-commits]

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@@ -568,7 +569,8 @@ let Features = "avx", Attributes = [NoThrow, Const, RequiredVectorWidth<256>] in
   def vec_set_v8si : X86Builtin<"_Vector<8, int>(_Vector<8, int>, int, _Constant int)">;
 }
 
-let Features = "avx2", Attributes = [NoThrow, Const, RequiredVectorWidth<256>] in {
+let Features = "avx2",
+    Attributes = [NoThrow, Const, Constexpr, RequiredVectorWidth<256>] in {
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RKSimon wrote:

same - undo this and move the byteshift declarations into the block with psrlqi256 etc.

https://github.com/llvm/llvm-project/pull/157403