[clang] [Clang] VectorExprEvaluator::VisitCallExpr / InterpretBuiltin - allow MMX/SSE/AVX2 PSIGN intrinsics to be used in constexpr (PR #163685)

[Simon Pilgrim via cfe-commits]

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@@ -12312,6 +12312,21 @@ bool VectorExprEvaluator::VisitCallExpr(const CallExpr *E) {
     return Success(APValue(ResultElements.data(), ResultElements.size()), E);
   }
 
+  case X86::BI__builtin_ia32_psignb128:
+  case X86::BI__builtin_ia32_psignb256:
+  case X86::BI__builtin_ia32_psignw128:
+  case X86::BI__builtin_ia32_psignw256:
+  case X86::BI__builtin_ia32_psignd128:
+  case X86::BI__builtin_ia32_psignd256:
+    return EvaluateBinOpExpr(
+        [](const APInt &AElem, const APInt &BElem) -> APInt {
----------------
RKSimon wrote:

```suggestion
        [](const APInt &AElem, const APInt &BElem) {
```

https://github.com/llvm/llvm-project/pull/163685