[clang] [clang] Implement __builtin_stdc_rotate_left, __builtin_stdc_rotate_right (PR #160259)

[Eli Friedman via cfe-commits]

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@@ -2318,6 +2318,67 @@ static bool BuiltinCountZeroBitsGeneric(Sema &S, CallExpr *TheCall) {
   return false;
 }
 
+/// Checks that __builtin_stdc_rotate_{left,right} was called with two
+/// arguments, that the first argument is an unsigned integer type, and that
+/// the second argument is an integer type.
+static bool BuiltinRotateGeneric(Sema &S, CallExpr *TheCall) {
+  if (S.checkArgCount(TheCall, 2))
+    return true;
+
+  ExprResult Arg0Res = S.DefaultLvalueConversion(TheCall->getArg(0));
+  if (Arg0Res.isInvalid())
+    return true;
+
+  Expr *Arg0 = Arg0Res.get();
+  TheCall->setArg(0, Arg0);
+
+  QualType Arg0Ty = Arg0->getType();
+  if (!Arg0Ty->isUnsignedIntegerType()) {
+    ExprResult ConvArg0Res = S.PerformImplicitConversion(
+        TheCall->getArg(0), S.Context.UnsignedIntTy, AssignmentAction::Passing);
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efriedma-quic wrote:

I'm not sure how @erichkeane expected you to do this.  Maybe PerformContextualImplicitConversion()?

https://github.com/llvm/llvm-project/pull/160259