[clang] [X86][Clang] VectorExprEvaluator::VisitCallExpr / InterpretBuiltin - allow element extraction/insertion intrinsics to be used in constexpr #159753 (PR #161302)

[Timm Baeder via cfe-commits]

================
@@ -12235,6 +12235,41 @@ bool VectorExprEvaluator::VisitCallExpr(const CallExpr *E) {
 
     return Success(APValue(ResultElements.data(), ResultElements.size()), E);
   }
+
+  case clang::X86::BI__builtin_ia32_vec_set_v4hi:
+  case clang::X86::BI__builtin_ia32_vec_set_v16qi:
+  case clang::X86::BI__builtin_ia32_vec_set_v8hi:
+  case clang::X86::BI__builtin_ia32_vec_set_v4si:
+  case clang::X86::BI__builtin_ia32_vec_set_v2di:
+  case clang::X86::BI__builtin_ia32_vec_set_v32qi:
+  case clang::X86::BI__builtin_ia32_vec_set_v16hi:
+  case clang::X86::BI__builtin_ia32_vec_set_v8si:
+  case clang::X86::BI__builtin_ia32_vec_set_v4di: {
+    APValue VecVal;
+    APSInt Scalar, IndexAPS;
+    if (!EvaluateVector(E->getArg(0), VecVal, Info) ||
+        !EvaluateInteger(E->getArg(1), Scalar, Info) ||
+        !EvaluateInteger(E->getArg(2), IndexAPS, Info))
+      return false;
+
+    QualType ElemTy = E->getType()->castAs<VectorType>()->getElementType();
+    unsigned ElemWidth = Info.Ctx.getIntWidth(ElemTy);
+    bool ElemUnsigned = ElemTy->isUnsignedIntegerOrEnumerationType();
+    Scalar.setIsUnsigned(ElemUnsigned);
+    APSInt ElemAPS = Scalar.extOrTrunc(ElemWidth);
+    APValue ElemAV(ElemAPS);
+
+    unsigned NumElts = VecVal.getVectorLength();
----------------
tbaederr wrote:

You're using "elem" everywhere (ElemTy, ElemWidth,...) and then suddenly Elts here.

https://github.com/llvm/llvm-project/pull/161302