Allow pass special constants to the write barrier #13497
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Some GC implementations want to always know when an object is written to, even if the written value is a special constant. Checking special constants in rb_obj_written was a micro-optimization that made assumptions about the GC implementation.
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Ah, I think this makes my comment over in ruby/strscan#156 (comment) incorrect. Do you think there are other places where folks might have skipped over special consts like I did because they didn't think it mattered? Will that cause problems with other GC implementations? |
For sure. There are plenty of micro-optimizations taken because of assumptions of how the garbage collector works. We're slowly removing these assumptions, but it won't be a small task.
Potentially., but not right now. We currently don't need this information to be accurate, just a best effort. We'll think about how to improve this when we need this information to be accurate. |
| @@ -24,7 +24,7 @@ | |||
| * In released versions of Ruby, this number is not defined since teeny | |||
| * versions of Ruby should guarantee ABI compatibility. | |||
| */ | |||
| #define RUBY_ABI_VERSION 1 | |||
| #define RUBY_ABI_VERSION 2 | |||
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include/ruby/internal/gc.h changed in an incompatible way so we need to bump the ABI version.
Some GC implementations want to always know when an object is written to, even if the written value is a special constant. Checking special constants in rb_obj_written was a micro-optimization that made assumptions about the GC implementation.