susematz / x86-64-abi Goto Github PK

The subsubsection "Data Representation" -> "Aggregates and Unions" -> "Bit-fields" contains the following text:

Bit-fields that are neither signed nor unsigned always have non-negative values.[ ...]

And consequently the figure "Bit-Field Ranges" shows unsigned ranges for these types of bit fields.

This is not in sync with current GCC. In fact, GCC assigns the signedness of the underlying type to a bit-field. For instance, an 'int' bit-field of size 1 has a value range from -1 to 0.