the compiler to emit a special header called <code>go_asm.h</code>,
which the .s files can then <code>#include</code>.
The file contains symbolic <code>#define</code> constants for the
offsets of Go struct fields, the sizes of Go struct types, and most
Go <code>const</code> declarations defined in the current package.
Go assembly should avoid making assumptions about the layout of Go
types and instead use these constants.