[clang] [clang][x86] Add constexpr support for VNNI intrinsics (PR #190549)

[NagaChaitanya Vellanki via cfe-commits]

================
@@ -1075,51 +1075,51 @@ let Features = "avx512f", Attributes = [NoThrow, Const, Constexpr, RequiredVecto
   def extractf32x4_mask : X86Builtin<"_Vector<4, float>(_Vector<16, float>, _Constant int, _Vector<4, float>, unsigned char)">;
 }
 
-let Features = "avx512vl,avx512vnni|avxvnni", Attributes = [NoThrow, Const, RequiredVectorWidth<128>] in {
+let Features = "avx512vl,avx512vnni|avxvnni", Attributes = [NoThrow, Const, Constexpr, RequiredVectorWidth<128>] in {
   def vpdpbusd128 : X86Builtin<"_Vector<4, int>(_Vector<4, int>, _Vector<16, unsigned char>, _Vector<16, char>)">;
 }
----------------
chaitanyav wrote:

we can combine the sections 

```
let Features = "avx512vl,avx512vnni|avxvnni", Attributes = [NoThrow, Const, Constexpr, RequiredVectorWidth<128>] in {
  def vpdpbusd128 : X86Builtin<"_Vector<4, int>(_Vector<4, int>, _Vector<16, unsigned char>, _Vector<16, char>)">;
  def vpdpbusds128 : X86Builtin<"_Vector<4, int>(_Vector<4, int>, _Vector<16, unsigned char>, _Vector<16, char>)">;
}

```

https://github.com/llvm/llvm-project/pull/190549