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refine last slice setting for large alignments

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This commit is contained in:
daan 2022-11-06 20:57:27 -08:00
parent 562efed54d
commit 651a99b35d
4 changed files with 20 additions and 21 deletions
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29
src/segment.c
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@ -277,7 +277,7 @@ static bool mi_segment_is_valid(mi_segment_t* segment, mi_segments_tld_t* tld) {
}
// and the last entry as well (for coalescing)
const mi_slice_t* last = slice + slice->slice_count - 1;
if (last > slice && last <= mi_segment_slices_end(segment)) {
if (last > slice && last < mi_segment_slices_end(segment)) {
mi_assert_internal(last->slice_offset == (slice->slice_count-1)*sizeof(mi_slice_t));
mi_assert_internal(last->slice_count == 0);
mi_assert_internal(last->xblock_size == 1);
@ -679,7 +679,7 @@ static void mi_segment_slice_split(mi_segment_t* segment, mi_slice_t* slice, siz
// Note: may still return NULL if committing the memory failed
static mi_page_t* mi_segment_span_allocate(mi_segment_t* segment, size_t slice_index, size_t slice_count, mi_segments_tld_t* tld) {
mi_assert_internal(slice_index < segment->slice_entries);
mi_slice_t* slice = &segment->slices[slice_index];
mi_slice_t* const slice = &segment->slices[slice_index];
mi_assert_internal(slice->xblock_size==0 || slice->xblock_size==1);
// commit before changing the slice data
@ -700,22 +700,21 @@ static mi_page_t* mi_segment_span_allocate(mi_segment_t* segment, size_t slice_i
size_t extra = slice_count-1;
if (extra > MI_MAX_SLICE_OFFSET) extra = MI_MAX_SLICE_OFFSET;
if (slice_index + extra >= segment->slice_entries) extra = segment->slice_entries - slice_index - 1; // huge objects may have more slices than avaiable entries in the segment->slices
slice++;
for (size_t i = 1; i <= extra; i++, slice++) {
slice->slice_offset = (uint32_t)(sizeof(mi_slice_t)*i);
slice->slice_count = 0;
slice->xblock_size = 1;
mi_slice_t* slice_next = slice + 1;
for (size_t i = 1; i <= extra; i++, slice_next++) {
slice_next->slice_offset = (uint32_t)(sizeof(mi_slice_t)*i);
slice_next->slice_count = 0;
slice_next->xblock_size = 1;
}
// and also for the last one (if not set already) (the last one is needed for coalescing)
// and also for the last one (if not set already) (the last one is needed for coalescing and for large alignments)
// note: the cast is needed for ubsan since the index can be larger than MI_SLICES_PER_SEGMENT for huge allocations (see #543)
size_t slice_last_index = slice_index + slice_count - 1;
if (slice_last_index >= segment->slice_entries) {
slice_last_index = segment->slice_entries;
}
mi_slice_t* last = &((mi_slice_t*)segment->slices)[slice_last_index];
if (last <= mi_segment_slices_end(segment) && last >= slice) {
last->slice_offset = (uint32_t)(sizeof(mi_slice_t)*(slice_last_index - slice_index));
mi_slice_t* last = slice + slice_count - 1;
mi_slice_t* end = (mi_slice_t*)mi_segment_slices_end(segment);
if (last > end) last = end;
if (last > slice) {
last->slice_offset = (uint32_t)(sizeof(mi_slice_t) * (last - slice));
last->slice_count = 0;
last->xblock_size = 1;
}