ulib/region-alloc/region-alloc.cpp

120     auto before = avail_regions_by_base_.upper_bound(region.base);
121     auto after  = before--;
125     if (before.IsValid()) {
126         before_end = before->base + before->size;  // exclusive end
127         if ((region.base >= before->base) && (region_end <= before_end)) {
132             if ((region.base == before->base) && (region_end == before_end)) {
133                 Region* removed = avail_regions_by_base_.erase(before);
142             // Case 2: before completely contains region.  The before region needs
145             if ((region.base != before->base) && (region_end != before_end)) {
154                 Region* first = avail_regions_by_size_.erase(*before);
165             // Case 3: region trims the front of before.  Update before's base and
169             if (region.base == before->base) {
172                 Region* bptr = avail_regions_by_size_.erase(*before);
180             // Case 4: region trims the end of before.  Update before's size and
182             ZX_DEBUG_ASSERT(region.base != before->base);
185             Region* bptr = avail_regions_by_size_.erase(*before);
201     // of the region which comes before us, and then consume some of the regions
205     // considering the before region.
206     if (before.IsValid()) {
207         ZX_DEBUG_ASSERT(region.base >= before->base);
210             // No matter what, 'before' needs to be removed from the size index.
211             Region* bptr = avail_regions_by_size_.erase(*before);
213             // If before's base is the same as the region's base, then we are
214             // subtracting out all of before.  Otherwise, we are trimming the back
215             // before and need to recompute its size and position in the size index.
226             // Either way, the region we are subtracting now starts where before
468         // If we only have to split before, then this region is not aligned
526     // Find the region which comes before us and the region which comes after us
528     auto before = avail_regions_by_base_.upper_bound(region->base);
529     auto after  = before--;
531     // Merge with the region which comes before us if we can.
533     if (before.IsValid()) {
534         ZX_DEBUG_ASSERT(before->base <= region->base);
536         uint64_t before_end = (before->base + before->size);    // exclusive end
539             region->base = before->base;
541             auto removed = avail_regions_by_base_.erase(before);
586     // Check the element before us in the tree.  If it exists, we know that it's