Adding macros to push pinning roots #43
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| #define JL_GC_ENCODE_PUSH(n) ((((size_t)(n))<<3)|1) | ||
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| // these only pin the root object itself | ||
| #define JL_GC_ENCODE_PUSHARGS_NO_TPIN(n) (((size_t)(n))<<3|4) |
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I don't know if Julia documents this anywhere. It is a good idea to explain what those bits are used for.
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There seems to be three different functions:
#define JL_GC_ENCODE_PUSHARGS(n) (((size_t)(n))<<2)
#define JL_GC_ENCODE_PUSH(n) ((((size_t)(n))<<2)|1)
#define JL_GC_ENCODE_PUSHFRAME(n) ((((size_t)(n))<<2)|2)
I think they currently use 2 bits (<<2). It seems to indicate what stuff you'd push onto the shadow stack, but I might ask around so we can document this properly.
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I am wondering if we should merge this. We need the changes in this PR for the static analyser as well. @udesou |
…at are/are not transitively pinning
Sounds good to me. I've added a comment to explain how the bits work, in particular for transitively pinning roots. If you have no issues with the PR, then we can merge it. |
Supporting processing roots in the shadow stack that are not transitively pinned (only the root object is pinned), and therefore should enable moving more objects. NB: Should be merged with mmtk/julia#43.
Supporting pushing roots to the shadow stack that are not transitively pinned (only the root object is pinned), and therefore should enable moving more objects.
For backwards compatibility the original functions will be used to represent transitively pinned roots, whereas the
*_RELAXEDversion will represent roots in which only the root object needs to be pinned. Therefore, to support moving move objects the goal is to replace as much as possible of the original functions with their_RELAXEDcounterpart.