[clang] [CIR] Upstream support for address of and dereference (PR #134317)

[Andy Kaylor via cfe-commits]

================
@@ -193,8 +334,23 @@ LValue CIRGenFunction::emitUnaryOpLValue(const UnaryOperator *e) {
 
   switch (op) {
   case UO_Deref: {
-    cgm.errorNYI(e->getSourceRange(), "UnaryOp dereference");
-    return LValue();
+    QualType t = e->getSubExpr()->getType()->getPointeeType();
+    assert(!t.isNull() && "CodeGenFunction::EmitUnaryOpLValue: Illegal type");
+
+    assert(!cir::MissingFeatures::lvalueBaseInfo());
+    assert(!cir::MissingFeatures::opTBAA());
+    Address addr = emitPointerWithAlignment(e->getSubExpr());
+
+    // Tag 'load' with deref attribute.
+    if (auto loadOp =
+            dyn_cast<cir::LoadOp>(addr.getPointer().getDefiningOp())) {
+      loadOp.setIsDerefAttr(mlir::UnitAttr::get(&getMLIRContext()));
----------------
andykaylor wrote:

@efriedma-quic Are you satisfied with the explanations above?

https://github.com/llvm/llvm-project/pull/134317