================
@@ -603,6 +606,64 @@ static void prepareTypeConverter(mlir::LLVMTypeConverter
&converter,
});
}
+// The unreachable code is not lowered by applyPartialConversion function
+// since it traverses blocks in the dominance order. At the same time we
+// do need to lower such code - otherwise verification errors occur.
+// For instance, the next CIR code:
+//
+// cir.func @foo(%arg0: !s32i) -> !s32i {
+// %4 = cir.cast(int_to_bool, %arg0 : !s32i), !cir.bool
+// cir.if %4 {
+// %5 = cir.const #cir.int<1> : !s32i
+// cir.return %5 : !s32i
+// } else {
+// %5 = cir.const #cir.int<0> : !s32i
+// cir.return %5 : !s32i
+// }
+// cir.return %arg0 : !s32i
+// }
+//
+// contains an unreachable return operation (the last one). After the
flattening
+// pass it will be placed into the unreachable block. And the possible error
+// after the lowering pass is: error: 'cir.return' op expects parent op to be
+// one of 'cir.func, cir.scope, cir.if ... The reason that this operation was
+// not lowered and the new parent is llvm.func.
+//
+// In the future we may want to get rid of this function and use DCE pass or
+// something similar. But now we need to guarantee the absence of the dialect
----------------
erichkeane wrote:
```suggestion
// something similar. But for now we need to guarantee the absence of the
dialect
```
https://github.com/llvm/llvm-project/pull/130648
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