Coverage Report

Created: 2018-06-21 18:56

/home/travis/build/MoarVM/MoarVM/src/gc/worklist.h
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/* A worklist holds the current set of pointers we have got in the queue
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 * to scan. We hide away the details of it behind this abstraction since
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 * the order in which we hand things back from it can have a big influence
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 * on locality in the copied/compacted heap, and thus mutator performance.
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 *
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 * For the time being, we do the simplest possible thing: just make it a
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 * stack. This actually has reasonable properties if we scan objects right
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 * after they are copied/moved, since an object's children will then come
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 * right after the object itself - unless they were copied/moved earlier.
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 * But things aren't quite so rosy for deeply nested data structures, where
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 * two siblings may thus end up far apart. Lots of stuff in the literature
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 * on these issues, but for now this is probably less bad than some of the
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 * other options.
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 */
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struct MVMGCWorklist {
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    /* The worklist itself. An array of addresses which hold pointers to
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     * collectables (yes, two levels of indirection, since we need to
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     * update addresses in copying/moving algorithms.) */
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    MVMCollectable ***list;
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    /* The number of items on the worklist. */
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    MVMuint32 items;
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    /* The number of items the work list is allocated to hold. */
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    MVMuint32 alloc;
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    /* Whether we should include gen2 entries. */
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    MVMuint8 include_gen2;
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};
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/* Some macros for doing stuff fast with worklists, defined to look like
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 * functions since perhaps they become them in the future if needed. */
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#if MVM_GC_DEBUG
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#define MVM_gc_worklist_add(tc, worklist, item) \
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    do { \
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        MVMCollectable **item_to_add = (MVMCollectable **)(item);\
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        if (*item_to_add) { \
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            if ((*item_to_add)->owner == 0) \
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                MVM_panic(1, "Zeroed owner in item added to GC worklist"); \
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            if ((*item_to_add)->owner > tc->instance->next_user_thread_id) \
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                MVM_panic(1, "Invalid owner in item added to GC worklist"); \
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            if ((*item_to_add)->flags & MVM_CF_DEBUG_IN_GEN2_FREE_LIST) \
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                MVM_panic(1, "Adding item to worklist already freed in gen2\n"); \
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            if ((*item_to_add)->flags & MVM_CF_FRAME && !((MVMFrame *)(*item_to_add))->static_info) \
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                MVM_panic(1, "Frame with NULL static_info added to worklist"); \
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            else if ((*item_to_add)->flags & MVM_CF_STABLE == 0 && !STABLE(*item_to_add)) \
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                MVM_panic(1, "NULL STable in item added to GC worklist"); \
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            if ((char *)*item_to_add >= (char *)tc->nursery_alloc && \
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                    (char *)*item_to_add < (char *)tc->nursery_alloc_limit) \
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                MVM_panic(1, "Adding pointer %p to past fromspace to GC worklist", \
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                    *item_to_add); \
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        } \
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        if (*item_to_add && (worklist->include_gen2 || !((*item_to_add)->flags & MVM_CF_SECOND_GEN))) { \
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            if (worklist->items == worklist->alloc) \
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                MVM_gc_worklist_add_slow(tc, worklist, item_to_add); \
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            else \
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                worklist->list[worklist->items++] = item_to_add; \
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        } \
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    } while (0)
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#else
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#define MVM_gc_worklist_add(tc, worklist, item) \
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26.5M
    do { \
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26.5M
        MVMCollectable **item_to_add = (MVMCollectable **)(item);\
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26.5M
        if (*item_to_add && (worklist->include_gen2 || !((*item_to_add)->flags & MVM_CF_SECOND_GEN))) { \
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4.40M
            if (worklist->items == worklist->alloc) \
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228
                MVM_gc_worklist_add_slow(tc, worklist, item_to_add); \
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4.40M
            else \
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4.40M
                worklist->list[worklist->items++] = item_to_add; \
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4.40M
        } \
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26.5M
    } while (0)
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#endif
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#define MVM_gc_worklist_get(tc, worklist) \
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4.40M
    (worklist->items ? \
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4.40M
        worklist->list[--worklist->items] : \
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4.40M
        NULL)
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/* Various functions for worklist manipulation. */
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MVMGCWorklist * MVM_gc_worklist_create(MVMThreadContext *tc, MVMuint8 include_gen2);
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MVM_PUBLIC void MVM_gc_worklist_add_slow(MVMThreadContext *tc, MVMGCWorklist *worklist, MVMCollectable **item);
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void MVM_gc_worklist_presize_for(MVMThreadContext *tc, MVMGCWorklist *worklist, MVMint32 items);
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void MVM_gc_worklist_destroy(MVMThreadContext *tc, MVMGCWorklist *worklist);
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/* The number of pointers we assume the list may need to hold initially;
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 * it will be resized as needed. */
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#define MVM_GC_WORKLIST_START_SIZE      256