search for: l878

Hello devs, Recently I've been working on a bug that can probably be fixed with the addition of a simple flag to a class descendant of `llvm::Value`. Without increasing the size of the class, I can just add this flag to `llvm::Value::SubclassData`. But this is not an easy task! This is because the offsetes/sizes of the data stored in the `SubclassData`, are hardcoded literals/enums. If you

...(bool a : 1; int b : 2;), it will not pack them into the same bitfield. > > Second, do we really need macros to do this? See the techniques used in > clang::VarDecl: > > https://github.com/llvm/llvm-project/blob/f20fc65887e2085332d111ee0b05736794423c72/clang/include/clang/AST/Decl.h#L878 > As written with a union between all the bitfields, the base class ends up > knowing everything about the derived classes, which is not ideal. But, you > could imagine a version of this that uses aligned char storage so that > subclasses could reinterpret_cast the subclass data memory...