[clang] [Clang][CodeGen] Avoid emitting poison immargs for __builtin_prefetch (PR #201623)

[Craig Topper via cfe-commits]

================
@@ -4308,8 +4308,12 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
     // FIXME: Technically these constants should of type 'int', yes?
     RW = (E->getNumArgs() > 1) ? EmitScalarExpr(E->getArg(1)) :
----------------
topperc wrote:

Confirmed that this works.

```
diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index 0cb5f9504978..7793d44ef2af 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -4305,10 +4305,11 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
   }
   case Builtin::BI__builtin_prefetch: {
     Value *Locality, *RW, *Address = EmitScalarExpr(E->getArg(0));
+    unsigned ICEArguments = 0x6;
     // FIXME: Technically these constants should of type 'int', yes?
-    RW = (E->getNumArgs() > 1) ? EmitScalarExpr(E->getArg(1)) :
+    RW = (E->getNumArgs() > 1) ? EmitScalarOrConstFoldImmArg(ICEArguments, 1, E) :
       llvm::ConstantInt::get(Int32Ty, 0);
-    Locality = (E->getNumArgs() > 2) ? EmitScalarExpr(E->getArg(2)) :
+    Locality = (E->getNumArgs() > 2) ? EmitScalarOrConstFoldImmArg(ICEArguments, 2, E) :
       llvm::ConstantInt::get(Int32Ty, 3);
     Value *Data = llvm::ConstantInt::get(Int32Ty, 1);
     Function *F = CGM.getIntrinsic(Intrinsic::prefetch, Address->getType());
```

https://github.com/llvm/llvm-project/pull/201623