Report SIP survivors

[cshung]

This change is intended to complete the work missed in #67889.
Regions swept in the plan phase can have survivors too, so we must also report them.

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Issue Details

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This change is intended to complete the work missed in #67889.
Regions swept in the plan phase can have survivors too, so we must also report them.

Author:	cshung
Assignees:	cshung
Labels:	area-GC-coreclr
Milestone:	-

[Maoni0]

I've written this in a slightly different way, let me know what you think. the idea is we form the start of a plug (if it hasn't been set) when we see a non free object , and end a plug when we see a free object. I think this code seems to convey that idea a bit more intuitively.

heap_segment* gc_heap::walk_relocation_sip (heap_segment* current_heap_segment, void* profiling_context, record_surv_fn fn)
{
    while (current_heap_segment && heap_segment_swept_in_plan (current_heap_segment))
    {
        uint8_t* start = heap_segment_mem (current_heap_segment);
        uint8_t* end = heap_segment_allocated (current_heap_segment);
        uint8_t* obj = start;
        uint8_t* plug_start = nullptr;
        while (obj < end)
        {
            if (((CObjectHeader*)obj)->IsFree())
            {
                if (plug_start)
                {
                    fn (plug_start, obj, 0, profiling_context, false, false);
                    plug_start = nullptr;
                }
            }
            else
            {
                if (!plug_start) 
                {
                    plug_start = obj;
                }
            }

            obj += Align (size (obj));
        }
        if (plug_start)
        {
            fn (plug_start, end, 0, profiling_context, false, false);
        }
        current_heap_segment = heap_segment_next_rw (current_heap_segment);
    }
    return current_heap_segment;
}