Update mimalloc to v2.1.2 (git-for-windows#4740)

The mimalloc project [has released a couple
versions](https://github.com/microsoft/mimalloc?tab=readme-ov-file#releases)
since we last integrated it into Git for Windows. Let's take the most
recent one.

This PR is structured in the following way:

1. Revert all mimalloc commits, in reverse chronological order (newest
first), marking them as `fixup!`s of the reverted commits.
2. Import (a subset of) mimalloc v2.1.2, marking it as an `amend!` of
the commit that originally imported mimalloc.
3. Replay the remaining mimalloc commits, in chronological order,
marking them as `fixup!`s of the original commits.

Author: dscho

Makefile

@@ -2088,8 +2088,10 @@ ifdef USE_MIMALLOC
 		compat/mimalloc/os.o \
 		compat/mimalloc/page.o \
 		compat/mimalloc/random.o \
+		compat/mimalloc/prim/windows/prim.o \
 		compat/mimalloc/segment.o \
 		compat/mimalloc/segment-cache.o \
+		compat/mimalloc/segment-map.o \
 		compat/mimalloc/stats.o
 
 	COMPAT_CFLAGS += -Icompat/mimalloc -DMI_DEBUG=0 -DUSE_MIMALLOC --std=gnu11

compat/mimalloc/alloc-aligned.c

@@ -6,9 +6,10 @@ terms of the MIT license. A copy of the license can be found in the file
 -----------------------------------------------------------------------------*/
 
 #include "mimalloc.h"
-#include "mimalloc-internal.h"
+#include "mimalloc/internal.h"
+#include "mimalloc/prim.h"  // mi_prim_get_default_heap
 
-#include <string.h>  // memset
+#include <string.h>     // memset
 
 // ------------------------------------------------------
 // Aligned Allocation
@@ -61,52 +62,44 @@ static mi_decl_noinline void* mi_heap_malloc_zero_aligned_at_fallback(mi_heap_t*
   mi_assert_internal(adjust < alignment);
   void* aligned_p = (void*)((uintptr_t)p + adjust);
   if (aligned_p != p) {
-    mi_page_set_has_aligned(_mi_ptr_page(p), true);
+    mi_page_t* page = _mi_ptr_page(p);
+    mi_page_set_has_aligned(page, true);
+    _mi_padding_shrink(page, (mi_block_t*)p, adjust + size);
   }
+  // todo: expand padding if overallocated ?
 
   mi_assert_internal(mi_page_usable_block_size(_mi_ptr_page(p)) >= adjust + size);
   mi_assert_internal(p == _mi_page_ptr_unalign(_mi_ptr_segment(aligned_p), _mi_ptr_page(aligned_p), aligned_p));
   mi_assert_internal(((uintptr_t)aligned_p + offset) % alignment == 0);
-  mi_assert_internal(mi_page_usable_block_size(_mi_ptr_page(p)) >= adjust + size);
+  mi_assert_internal(mi_usable_size(aligned_p)>=size);
+  mi_assert_internal(mi_usable_size(p) == mi_usable_size(aligned_p)+adjust);
 
   // now zero the block if needed
-  if (zero && alignment > MI_ALIGNMENT_MAX) {
-    const ptrdiff_t diff = (uint8_t*)aligned_p - (uint8_t*)p;
-    const ptrdiff_t zsize = mi_page_usable_block_size(_mi_ptr_page(p)) - diff - MI_PADDING_SIZE;
-    if (zsize > 0) { _mi_memzero(aligned_p, zsize); }
+  if (alignment > MI_ALIGNMENT_MAX) {
+    // for the tracker, on huge aligned allocations only from the start of the large block is defined
+    mi_track_mem_undefined(aligned_p, size);
+    if (zero) {
+      _mi_memzero_aligned(aligned_p, mi_usable_size(aligned_p));
+    }
   }
 
-  #if MI_TRACK_ENABLED
   if (p != aligned_p) {
-    mi_track_free_size(p, oversize);
-    mi_track_malloc(aligned_p, size, zero);
-  }
-  else {
-    mi_track_resize(aligned_p, oversize, size);
+    mi_track_align(p,aligned_p,adjust,mi_usable_size(aligned_p));
   }
-  #endif
   return aligned_p;
 }
 
 // Primitive aligned allocation
 static void* mi_heap_malloc_zero_aligned_at(mi_heap_t* const heap, const size_t size, const size_t alignment, const size_t offset, const bool zero) mi_attr_noexcept
 {
   // note: we don't require `size > offset`, we just guarantee that the address at offset is aligned regardless of the allocated size.
-  mi_assert(alignment > 0);
   if mi_unlikely(alignment == 0 || !_mi_is_power_of_two(alignment)) { // require power-of-two (see <https://en.cppreference.com/w/c/memory/aligned_alloc>)
     #if MI_DEBUG > 0
     _mi_error_message(EOVERFLOW, "aligned allocation requires the alignment to be a power-of-two (size %zu, alignment %zu)\n", size, alignment);
     #endif
     return NULL;
   }
-  /*
-  if mi_unlikely(alignment > MI_ALIGNMENT_MAX) {  // we cannot align at a boundary larger than this (or otherwise we cannot find segment headers)
-    #if MI_DEBUG > 0
-    _mi_error_message(EOVERFLOW, "aligned allocation has a maximum alignment of %zu (size %zu, alignment %zu)\n", MI_ALIGNMENT_MAX, size, alignment);
-    #endif
-    return NULL;
-  }
-  */
+
   if mi_unlikely(size > PTRDIFF_MAX) {          // we don't allocate more than PTRDIFF_MAX (see <https://sourceware.org/ml/libc-announce/2019/msg00001.html>)
     #if MI_DEBUG > 0
     _mi_error_message(EOVERFLOW, "aligned allocation request is too large (size %zu, alignment %zu)\n", size, alignment);
@@ -146,9 +139,9 @@ mi_decl_nodiscard mi_decl_restrict void* mi_heap_malloc_aligned_at(mi_heap_t* he
 }
 
 mi_decl_nodiscard mi_decl_restrict void* mi_heap_malloc_aligned(mi_heap_t* heap, size_t size, size_t alignment) mi_attr_noexcept {
+  if mi_unlikely(alignment == 0 || !_mi_is_power_of_two(alignment)) return NULL;
   #if !MI_PADDING
   // without padding, any small sized allocation is naturally aligned (see also `_mi_segment_page_start`)
-  if (!_mi_is_power_of_two(alignment)) return NULL;
   if mi_likely(_mi_is_power_of_two(size) && size >= alignment && size <= MI_SMALL_SIZE_MAX)
   #else
   // with padding, we can only guarantee this for fixed alignments
@@ -164,6 +157,11 @@ mi_decl_nodiscard mi_decl_restrict void* mi_heap_malloc_aligned(mi_heap_t* heap,
   }
 }
 
+// ensure a definition is emitted
+#if defined(__cplusplus)
+static void* _mi_heap_malloc_aligned = (void*)&mi_heap_malloc_aligned;
+#endif
+
 // ------------------------------------------------------
 // Aligned Allocation
 // ------------------------------------------------------
@@ -187,27 +185,27 @@ mi_decl_nodiscard mi_decl_restrict void* mi_heap_calloc_aligned(mi_heap_t* heap,
 }
 
 mi_decl_nodiscard mi_decl_restrict void* mi_malloc_aligned_at(size_t size, size_t alignment, size_t offset) mi_attr_noexcept {
-  return mi_heap_malloc_aligned_at(mi_get_default_heap(), size, alignment, offset);
+  return mi_heap_malloc_aligned_at(mi_prim_get_default_heap(), size, alignment, offset);
 }
 
 mi_decl_nodiscard mi_decl_restrict void* mi_malloc_aligned(size_t size, size_t alignment) mi_attr_noexcept {
-  return mi_heap_malloc_aligned(mi_get_default_heap(), size, alignment);
+  return mi_heap_malloc_aligned(mi_prim_get_default_heap(), size, alignment);
 }
 
 mi_decl_nodiscard mi_decl_restrict void* mi_zalloc_aligned_at(size_t size, size_t alignment, size_t offset) mi_attr_noexcept {
-  return mi_heap_zalloc_aligned_at(mi_get_default_heap(), size, alignment, offset);
+  return mi_heap_zalloc_aligned_at(mi_prim_get_default_heap(), size, alignment, offset);
 }
 
 mi_decl_nodiscard mi_decl_restrict void* mi_zalloc_aligned(size_t size, size_t alignment) mi_attr_noexcept {
-  return mi_heap_zalloc_aligned(mi_get_default_heap(), size, alignment);
+  return mi_heap_zalloc_aligned(mi_prim_get_default_heap(), size, alignment);
 }
 
 mi_decl_nodiscard mi_decl_restrict void* mi_calloc_aligned_at(size_t count, size_t size, size_t alignment, size_t offset) mi_attr_noexcept {
-  return mi_heap_calloc_aligned_at(mi_get_default_heap(), count, size, alignment, offset);
+  return mi_heap_calloc_aligned_at(mi_prim_get_default_heap(), count, size, alignment, offset);
 }
 
 mi_decl_nodiscard mi_decl_restrict void* mi_calloc_aligned(size_t count, size_t size, size_t alignment) mi_attr_noexcept {
-  return mi_heap_calloc_aligned(mi_get_default_heap(), count, size, alignment);
+  return mi_heap_calloc_aligned(mi_prim_get_default_heap(), count, size, alignment);
 }
 
 
@@ -225,19 +223,13 @@ static void* mi_heap_realloc_zero_aligned_at(mi_heap_t* heap, void* p, size_t ne
     return p;  // reallocation still fits, is aligned and not more than 50% waste
   }
   else {
+    // note: we don't zero allocate upfront so we only zero initialize the expanded part
     void* newp = mi_heap_malloc_aligned_at(heap,newsize,alignment,offset);
     if (newp != NULL) {
       if (zero && newsize > size) {
-	const mi_page_t* page = _mi_ptr_page(newp);
-	if (page->is_zero) {
-	  // already zero initialized
-	  mi_assert_expensive(mi_mem_is_zero(newp,newsize));
-	}
-	else {
-	  // also set last word in the previous allocation to zero to ensure any padding is zero-initialized
-	  size_t start = (size >= sizeof(intptr_t) ? size - sizeof(intptr_t) : 0);
-	  memset((uint8_t*)newp + start, 0, newsize - start);
-	}
+	// also set last word in the previous allocation to zero to ensure any padding is zero-initialized
+	size_t start = (size >= sizeof(intptr_t) ? size - sizeof(intptr_t) : 0);
+	_mi_memzero((uint8_t*)newp + start, newsize - start);
       }
       _mi_memcpy_aligned(newp, p, (newsize > size ? size : newsize));
       mi_free(p); // only free if successful
@@ -282,25 +274,25 @@ mi_decl_nodiscard void* mi_heap_recalloc_aligned(mi_heap_t* heap, void* p, size_
 }
 
 mi_decl_nodiscard void* mi_realloc_aligned_at(void* p, size_t newsize, size_t alignment, size_t offset) mi_attr_noexcept {
-  return mi_heap_realloc_aligned_at(mi_get_default_heap(), p, newsize, alignment, offset);
+  return mi_heap_realloc_aligned_at(mi_prim_get_default_heap(), p, newsize, alignment, offset);
 }
 
 mi_decl_nodiscard void* mi_realloc_aligned(void* p, size_t newsize, size_t alignment) mi_attr_noexcept {
-  return mi_heap_realloc_aligned(mi_get_default_heap(), p, newsize, alignment);
+  return mi_heap_realloc_aligned(mi_prim_get_default_heap(), p, newsize, alignment);
 }
 
 mi_decl_nodiscard void* mi_rezalloc_aligned_at(void* p, size_t newsize, size_t alignment, size_t offset) mi_attr_noexcept {
-  return mi_heap_rezalloc_aligned_at(mi_get_default_heap(), p, newsize, alignment, offset);
+  return mi_heap_rezalloc_aligned_at(mi_prim_get_default_heap(), p, newsize, alignment, offset);
 }
 
 mi_decl_nodiscard void* mi_rezalloc_aligned(void* p, size_t newsize, size_t alignment) mi_attr_noexcept {
-  return mi_heap_rezalloc_aligned(mi_get_default_heap(), p, newsize, alignment);
+  return mi_heap_rezalloc_aligned(mi_prim_get_default_heap(), p, newsize, alignment);
 }
 
 mi_decl_nodiscard void* mi_recalloc_aligned_at(void* p, size_t newcount, size_t size, size_t alignment, size_t offset) mi_attr_noexcept {
-  return mi_heap_recalloc_aligned_at(mi_get_default_heap(), p, newcount, size, alignment, offset);
+  return mi_heap_recalloc_aligned_at(mi_prim_get_default_heap(), p, newcount, size, alignment, offset);
 }
 
 mi_decl_nodiscard void* mi_recalloc_aligned(void* p, size_t newcount, size_t size, size_t alignment) mi_attr_noexcept {
-  return mi_heap_recalloc_aligned(mi_get_default_heap(), p, newcount, size, alignment);
+  return mi_heap_recalloc_aligned(mi_prim_get_default_heap(), p, newcount, size, alignment);
 }