Function free_fastpath

BeefRT/JEMalloc/src/jemalloc.c:3064–3155

Returns whether or not the free attempt was successful. */

/* Returns whether or not the free attempt was successful. */
JEMALLOC_ALWAYS_INLINE
bool free_fastpath(void *ptr, size_t size, bool size_hint) {
	tsd_t *tsd = tsd_get(false);
	/* The branch gets optimized away unless tsd_get_allocates(). */
	if (unlikely(tsd == NULL)) {
		return false;
	}
	/*
	 *  The tsd_fast() / initialized checks are folded into the branch
	 *  testing (deallocated_after >= threshold) later in this function.
	 *  The threshold will be set to 0 when !tsd_fast.
	 */
	assert(tsd_fast(tsd) ||
	    *tsd_thread_deallocated_next_event_fastp_get_unsafe(tsd) == 0);

	emap_alloc_ctx_t alloc_ctx;
	if (!size_hint) {
		bool err = emap_alloc_ctx_try_lookup_fast(tsd,
		    &arena_emap_global, ptr, &alloc_ctx);

		/* Note: profiled objects will have alloc_ctx.slab set */
		if (unlikely(err || !alloc_ctx.slab ||
		    free_fastpath_nonfast_aligned(ptr,
		    /* check_prof */ false))) {
			return false;
		}
		assert(alloc_ctx.szind != SC_NSIZES);
	} else {
		/*
		 * Check for both sizes that are too large, and for sampled /
		 * special aligned objects.  The alignment check will also check
		 * for null ptr.
		 */
		if (unlikely(size > SC_LOOKUP_MAXCLASS ||
		    free_fastpath_nonfast_aligned(ptr,
		    /* check_prof */ true))) {
			return false;
		}
		alloc_ctx.szind = sz_size2index_lookup(size);
		/* Max lookup class must be small. */
		assert(alloc_ctx.szind < SC_NBINS);
		/* This is a dead store, except when opt size checking is on. */
		alloc_ctx.slab = true;
	}
	/*
	 * Currently the fastpath only handles small sizes.  The branch on
	 * SC_LOOKUP_MAXCLASS makes sure of it.  This lets us avoid checking
	 * tcache szind upper limit (i.e. tcache_maxclass) as well.
	 */
	assert(alloc_ctx.slab);

	uint64_t deallocated, threshold;
	te_free_fastpath_ctx(tsd, &deallocated, &threshold);

	size_t usize = sz_index2size(alloc_ctx.szind);
	uint64_t deallocated_after = deallocated + usize;
	/*
	 * Check for events and tsd non-nominal (fast_threshold will be set to