[clang] [CIR] Upstream handling for __builtin_prefetch (PR #164387)

[Sirui Mu via cfe-commits]

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@@ -454,6 +454,27 @@ RValue CIRGenFunction::emitBuiltinExpr(const GlobalDecl &gd, unsigned builtinID,
     assert(!cir::MissingFeatures::coroSizeBuiltinCall());
     return getUndefRValue(e->getType());
   }
+  case Builtin::BI__builtin_prefetch: {
+    auto evaluateOperandAsInt = [&](const Expr *arg) {
+      Expr::EvalResult res;
+      [[maybe_unused]] bool evalSucceed =
+          arg->EvaluateAsInt(res, cgm.getASTContext());
+      assert(evalSucceed && "expression should be able to evaluate as int");
+      return res.Val.getInt().getZExtValue();
+    };
+
+    bool isWrite = false;
+    if (e->getNumArgs() > 1)
+      isWrite = evaluateOperandAsInt(e->getArg(1));
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Lancern wrote:

Could you include a negative test for this branch? (i.e. test the case when the if condition does not hold.)

https://github.com/llvm/llvm-project/pull/164387