wip: adding mi_remap; first working version

include/mimalloc/internal.h

@@ -174,6 +174,9 @@ void       _mi_page_reclaim(mi_heap_t* heap, mi_page_t* page);   // callback fro
 size_t     _mi_bin_size(uint8_t bin);           // for stats
 uint8_t    _mi_bin(size_t size);                // for stats
 
+void       _mi_heap_huge_page_attach(mi_heap_t* heap, mi_page_t* page);
+void       _mi_heap_huge_page_detach(mi_heap_t* heap, mi_page_t* page);
+
 // "heap.c"
 void       _mi_heap_destroy_pages(mi_heap_t* heap);
 void       _mi_heap_collect_abandon(mi_heap_t* heap);

src/alloc.c

@@ -24,6 +24,30 @@ terms of the MIT license. A copy of the license can be found in the file
 // Allocation
 // ------------------------------------------------------
 
+#if MI_PADDING
+static void mi_padding_init(mi_page_t* page, mi_block_t* block, size_t size /* block size minus MI_PADDING_SIZE */) {
+  mi_padding_t* const padding = (mi_padding_t*)((uint8_t*)block + mi_page_usable_block_size(page));
+  ptrdiff_t delta = ((uint8_t*)padding - (uint8_t*)block - size);
+  #if (MI_DEBUG>=2)
+    mi_assert_internal(delta >= 0 && mi_page_usable_block_size(page) >= (size + delta));
+  #endif
+  mi_track_mem_defined(padding, sizeof(mi_padding_t));  // note: re-enable since mi_page_usable_block_size may set noaccess
+  padding->canary = (uint32_t)(mi_ptr_encode(page, block, page->keys));
+  padding->delta = (uint32_t)(delta);
+  #if MI_PADDING_CHECK
+  if (!mi_page_is_huge(page)) {
+    uint8_t* fill = (uint8_t*)padding - delta;
+    const size_t maxpad = (delta > MI_MAX_ALIGN_SIZE ? MI_MAX_ALIGN_SIZE : delta); // set at most N initial padding bytes
+    for (size_t i = 0; i < maxpad; i++) { fill[i] = MI_DEBUG_PADDING; }
+  }
+  #endif
+}
+#else
+static void mi_padding_init(mi_page_t* page, mi_block_t* block, size_t size) {
+  MI_UNUSED(page); MI_UNUSED(block); MI_UNUSED(size);
+}
+#endif
+
 // Fast allocation in a page: just pop from the free list.
 // Fall back to generic allocation only if the list is empty.
 extern inline void* _mi_page_malloc(mi_heap_t* heap, mi_page_t* page, size_t size, bool zero) mi_attr_noexcept {
@@ -81,24 +105,7 @@ extern inline void* _mi_page_malloc(mi_heap_t* heap, mi_page_t* page, size_t siz
   }
 #endif
 
-#if MI_PADDING // && !MI_TRACK_ENABLED
-  mi_padding_t* const padding = (mi_padding_t*)((uint8_t*)block + mi_page_usable_block_size(page));
-  ptrdiff_t delta = ((uint8_t*)padding - (uint8_t*)block - (size - MI_PADDING_SIZE));
-  #if (MI_DEBUG>=2)
-  mi_assert_internal(delta >= 0 && mi_page_usable_block_size(page) >= (size - MI_PADDING_SIZE + delta));
-  #endif
-  mi_track_mem_defined(padding,sizeof(mi_padding_t));  // note: re-enable since mi_page_usable_block_size may set noaccess
-  padding->canary = (uint32_t)(mi_ptr_encode(page,block,page->keys));
-  padding->delta  = (uint32_t)(delta);
-  #if MI_PADDING_CHECK
-  if (!mi_page_is_huge(page)) {
-    uint8_t* fill = (uint8_t*)padding - delta;
-    const size_t maxpad = (delta > MI_MAX_ALIGN_SIZE ? MI_MAX_ALIGN_SIZE : delta); // set at most N initial padding bytes
-    for (size_t i = 0; i < maxpad; i++) { fill[i] = MI_DEBUG_PADDING; }
-  }
-  #endif
-#endif
-
+  mi_padding_init(page, block, size - MI_PADDING_SIZE);
   return block;
 }
 
@@ -807,12 +814,14 @@ mi_decl_nodiscard void* mi_zalloc_remappable(size_t size) mi_attr_noexcept {
 mi_decl_nodiscard void* mi_remap(void* p, size_t newsize) mi_attr_noexcept {
   if (p == NULL) return mi_malloc(newsize);
 
+  const size_t padsize = newsize + MI_PADDING_SIZE;
   mi_segment_t* segment = mi_checked_ptr_segment(p, "mi_remap");
   mi_assert_internal(segment != NULL);
-  mi_page_t* const page = _mi_segment_page_of(segment, p);
+  mi_page_t* page = _mi_segment_page_of(segment, p);  
+  mi_block_t* block = _mi_page_ptr_unalign(segment, page, p);
   const size_t bsize = mi_page_usable_block_size(page);
-  if (bsize >= newsize) {
-    // TODO: adjust padding
+  if (bsize >= padsize) {
+    mi_padding_init(page, block, newsize);
     return p;
   }
 
@@ -820,14 +829,22 @@ mi_decl_nodiscard void* mi_remap(void* p, size_t newsize) mi_attr_noexcept {
   if (segment->thread_id == heap->thread_id &&
       segment->memid.memkind == MI_MEM_OS_REMAP) 
   {
-    mi_heap_t* heap = mi_prim_get_default_heap();
-    mi_block_t* block = _mi_segment_huge_page_remap(segment, page, (mi_block_t*)p, newsize, &heap->tld->segments);
+    mi_assert_internal((void*)block == p);
+    _mi_heap_huge_page_detach(heap, page);
+    block = _mi_segment_huge_page_remap(segment, page, block, padsize, &heap->tld->segments);
     if (block != NULL) {     
-      // TODO: adjust padding?
+      segment = mi_checked_ptr_segment(block, "mi_remap");
+      page = _mi_segment_page_of(segment, block);
+      mi_padding_init(page, block, newsize);
+      _mi_heap_huge_page_attach(heap, page);
       return block;
     }
+    else {
+      _mi_heap_huge_page_attach(heap, page);
+    }
   }
-  _mi_warning_message("unable to remap block, fall back to reallocation (address: %p from %zu bytes to %zu bytes)\n", p, 0, newsize);
+  _mi_warning_message("unable to remap block, fall back to reallocation (address: %p from %zu bytes to %zu bytes)\n", p, mi_usable_size(p), newsize);
+
   return mi_realloc(p, newsize);
 }
 

src/page.c

@@ -403,6 +403,27 @@ void _mi_page_abandon(mi_page_t* page, mi_page_queue_t* pq) {
   _mi_segment_page_abandon(page,segments_tld);
 }
 
+// Detach a huge page (used for remapping)
+void _mi_heap_huge_page_detach(mi_heap_t* heap, mi_page_t* page) {
+  mi_assert_internal(mi_page_heap(page) == heap);
+  #if !MI_HUGE_PAGE_ABANDON
+  mi_page_queue_t* pq = mi_page_queue_of(page);
+  mi_assert_internal(mi_page_queue_is_huge(pq));
+  mi_page_queue_remove(pq, page);
+  #endif
+}
+
+// (re)attach a huge page
+void _mi_heap_huge_page_attach(mi_heap_t* heap, mi_page_t* page) {
+  mi_assert_internal(mi_page_heap(page) == heap);
+#if !MI_HUGE_PAGE_ABANDON
+  mi_page_queue_t* pq = mi_page_queue(heap, MI_HUGE_OBJ_SIZE_MAX); // not block_size as that can be low if the page_alignment > 0
+  mi_assert_internal(mi_page_queue_is_huge(pq));
+  mi_page_queue_push(heap, pq, page);
+#endif  
+}
+
+
 
 // Free a page with no more free blocks
 void _mi_page_free(mi_page_t* page, mi_page_queue_t* pq, bool force) {

src/prim/windows/prim.c

@@ -629,7 +629,8 @@ void _mi_prim_thread_associate_default_heap(mi_heap_t* heap) {
 
 int _mi_prim_alloc_remappable(size_t size, size_t future_reserve, bool* is_pinned, bool* is_zero, void** addr, void** remap_info ) {
   MI_UNUSED(size); MI_UNUSED(future_reserve); MI_UNUSED(is_pinned); MI_UNUSED(is_zero); MI_UNUSED(addr); MI_UNUSED(remap_info);
-  return EINVAL;
+  // return EINVAL;
+  return _mi_prim_alloc(size, 1, true, true, is_pinned, is_zero, addr);
 }
 
 int _mi_prim_realloc_remappable(void* addr, size_t size, size_t newsize, bool* extend_is_zero, void** newaddr, void** remap_info ) {
@@ -639,5 +640,6 @@ int _mi_prim_realloc_remappable(void* addr, size_t size, size_t newsize, bool* e
 
 int _mi_prim_free_remappable(void* addr, size_t size, void* remap_info ) {
   MI_UNUSED(addr); MI_UNUSED(size); MI_UNUSED(remap_info);
-  return EINVAL;
+  return _mi_prim_free(addr, size);
+  // return EINVAL;
 }

src/segment.c

@@ -1317,6 +1317,8 @@ mi_block_t* _mi_segment_huge_page_remap(mi_segment_t* segment, mi_page_t* page,
     newsegment->segment_size = newssize;
     newsegment->cookie = _mi_ptr_cookie(newsegment);
     mi_segment_protect(newsegment, true, tld->os);
+    _mi_segment_map_freed_at(segment);
+    _mi_segment_map_allocated_at(newsegment);
   }
 
   mi_block_t* newblock = (mi_block_t*)((uint8_t*)newsegment + block_ofs);

test/main-override-static.c

@@ -229,6 +229,7 @@ static void test_remap(void) {
     p = mi_remap(p, size + inc);
     memset(p + size, i, inc);
     size += inc;
+    printf("%3d: increased to size %zu\n", i, size);
   }
   mi_free(p);
 }