The compiler.codegen.gc-maps vocab serializes a compiled words gc maps into a space-efficient format which is appended to the end of the code block.
Every code block generated either ends with:
or
For example, if there are three gc maps and each contain four roots, then bit 0-3 in the bitmap would indicate liveness of the first gc maps roots, 4-7 of the second and 8-11 of the third.
Main entry point:
Every code block generated either ends with:
| • | uint 0 |
or
| • | a bitmap representing the indices of the spill slots that contain roots in each gc map |
| • | uint[] base pointers |
| • | uint[] return addresses |
| • | uint largest GC root spill slot |
| • | uint largest derived root spill slot |
| • | int number of return addresses/gc maps |
For example, if there are three gc maps and each contain four roots, then bit 0-3 in the bitmap would indicate liveness of the first gc maps roots, 4-7 of the second and 8-11 of the third.
Main entry point:
emit-gc-maps ( -- )