Import the source code of mimalloc

This commit imports mimalloc's source code as per 114d05c (bump to
version 1.1, 2019-10-07), as fetched from the v1.1.0 tag at
https://github.com/microsoft/mimalloc.

The .c files are from the src/ subdirectory, and the .h files from the
include/ subdirectory. We will subsequently modify the source code to
accommodate building within Git's context.

Since we plan on using the `mi_*()` family of functions, we skip the
C++-specific source code, some POSIX compliant functions to interact
with mimalloc, and the code that wants to support auto-magic overriding
of the `malloc()` function (mimalloc-new-delete.h, alloc-posix.c,
mimalloc-override.h, alloc-override.c, alloc-override-osx.c,
alloc-override-win.c and static.c).

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

compat/mimalloc/alloc-aligned.c

@@ -0,0 +1,204 @@
+/* ----------------------------------------------------------------------------
+Copyright (c) 2018, Microsoft Research, Daan Leijen
+This is free software; you can redistribute it and/or modify it under the
+terms of the MIT license. A copy of the license can be found in the file
+"LICENSE" at the root of this distribution.
+-----------------------------------------------------------------------------*/
+
+#include "mimalloc.h"
+#include "mimalloc-internal.h"
+
+#include <string.h>  // memset, memcpy
+
+// ------------------------------------------------------
+// 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 && alignment % sizeof(void*) == 0);
+  if (mi_unlikely(size > PTRDIFF_MAX)) return NULL;   // we don't allocate more than PTRDIFF_MAX (see <https://sourceware.org/ml/libc-announce/2019/msg00001.html>)
+  if (mi_unlikely(alignment==0 || !_mi_is_power_of_two(alignment))) return NULL; // require power-of-two (see <https://en.cppreference.com/w/c/memory/aligned_alloc>)
+  const uintptr_t align_mask = alignment-1;  // for any x, `(x & align_mask) == (x % alignment)`
+  
+  // try if there is a small block available with just the right alignment
+  if (mi_likely(size <= MI_SMALL_SIZE_MAX)) {
+    mi_page_t* page = _mi_heap_get_free_small_page(heap,size);
+    const bool is_aligned = (((uintptr_t)page->free+offset) & align_mask)==0;
+    if (mi_likely(page->free != NULL && is_aligned))
+    {
+      #if MI_STAT>1
+      mi_heap_stat_increase( heap, malloc, size);
+      #endif
+      void* p = _mi_page_malloc(heap,page,size); // TODO: inline _mi_page_malloc
+      mi_assert_internal(p != NULL);
+      mi_assert_internal(((uintptr_t)p + offset) % alignment == 0);
+      if (zero) _mi_block_zero_init(page,p,size);
+      return p;
+    }
+  }
+
+  // use regular allocation if it is guaranteed to fit the alignment constraints
+  if (offset==0 && alignment<=size && size<=MI_MEDIUM_OBJ_SIZE_MAX && (size&align_mask)==0) {
+    void* p = _mi_heap_malloc_zero(heap, size, zero);
+    mi_assert_internal(p == NULL || ((uintptr_t)p % alignment) == 0);
+    return p;
+  }
+  
+  // otherwise over-allocate
+  void* p = _mi_heap_malloc_zero(heap, size + alignment - 1, zero);
+  if (p == NULL) return NULL;
+
+  // .. and align within the allocation
+  uintptr_t adjust = alignment - (((uintptr_t)p + offset) & align_mask);
+  mi_assert_internal(adjust % sizeof(uintptr_t) == 0);
+  void* aligned_p = (adjust == alignment ? p : (void*)((uintptr_t)p + adjust));
+  if (aligned_p != p) mi_page_set_has_aligned(_mi_ptr_page(p), true); 
+  mi_assert_internal(((uintptr_t)aligned_p + offset) % alignment == 0);
+  mi_assert_internal( p == _mi_page_ptr_unalign(_mi_ptr_segment(aligned_p),_mi_ptr_page(aligned_p),aligned_p) );
+  return aligned_p;
+}
+
+
+void* mi_heap_malloc_aligned_at(mi_heap_t* heap, size_t size, size_t alignment, size_t offset) mi_attr_noexcept {
+  return mi_heap_malloc_zero_aligned_at(heap, size, alignment, offset, false);
+}
+
+void* mi_heap_malloc_aligned(mi_heap_t* heap, size_t size, size_t alignment) mi_attr_noexcept {
+  return mi_heap_malloc_aligned_at(heap, size, alignment, 0);
+}
+
+void* mi_heap_zalloc_aligned_at(mi_heap_t* heap, size_t size, size_t alignment, size_t offset) mi_attr_noexcept {
+  return mi_heap_malloc_zero_aligned_at(heap, size, alignment, offset, true);
+}
+
+void* mi_heap_zalloc_aligned(mi_heap_t* heap, size_t size, size_t alignment) mi_attr_noexcept {
+  return mi_heap_zalloc_aligned_at(heap, size, alignment, 0);
+}
+
+void* mi_heap_calloc_aligned_at(mi_heap_t* heap, size_t count, size_t size, size_t alignment, size_t offset) mi_attr_noexcept {
+  size_t total;
+  if (mi_mul_overflow(count, size, &total)) return NULL;
+  return mi_heap_zalloc_aligned_at(heap, total, alignment, offset);
+}
+
+void* mi_heap_calloc_aligned(mi_heap_t* heap, size_t count, size_t size, size_t alignment) mi_attr_noexcept {
+  return mi_heap_calloc_aligned_at(heap,count,size,alignment,0);
+}
+
+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);
+}
+
+void* mi_malloc_aligned(size_t size, size_t alignment) mi_attr_noexcept {
+  return mi_heap_malloc_aligned(mi_get_default_heap(), size, alignment);
+}
+
+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);
+}
+
+void* mi_zalloc_aligned(size_t size, size_t alignment) mi_attr_noexcept {
+  return mi_heap_zalloc_aligned(mi_get_default_heap(), size, alignment);
+}
+
+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);
+}
+
+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);
+}
+
+
+static void* mi_heap_realloc_zero_aligned_at(mi_heap_t* heap, void* p, size_t newsize, size_t alignment, size_t offset, bool zero) mi_attr_noexcept {
+  mi_assert(alignment > 0);
+  if (alignment <= sizeof(uintptr_t)) return _mi_heap_realloc_zero(heap,p,newsize,zero);
+  if (p == NULL) return mi_heap_malloc_zero_aligned_at(heap,newsize,alignment,offset,zero);
+  size_t size = mi_usable_size(p);
+  if (newsize <= size && newsize >= (size - (size / 2))
+      && (((uintptr_t)p + offset) % alignment) == 0) {
+    return p;  // reallocation still fits, is aligned and not more than 50% waste
+  }
+  else {
+    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->flags.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);
+        }
+      }
+      memcpy(newp, p, (newsize > size ? size : newsize));
+      mi_free(p); // only free if successful
+    }
+    return newp;
+  }
+}
+
+static void* mi_heap_realloc_zero_aligned(mi_heap_t* heap, void* p, size_t newsize, size_t alignment, bool zero) mi_attr_noexcept {
+  mi_assert(alignment > 0);
+  if (alignment <= sizeof(uintptr_t)) return _mi_heap_realloc_zero(heap,p,newsize,zero);
+  size_t offset = ((uintptr_t)p % alignment); // use offset of previous allocation (p can be NULL)
+  return mi_heap_realloc_zero_aligned_at(heap,p,newsize,alignment,offset,zero);
+}
+
+void* mi_heap_realloc_aligned_at(mi_heap_t* heap, void* p, size_t newsize, size_t alignment, size_t offset) mi_attr_noexcept {
+  return mi_heap_realloc_zero_aligned_at(heap,p,newsize,alignment,offset,false);
+}
+
+void* mi_heap_realloc_aligned(mi_heap_t* heap, void* p, size_t newsize, size_t alignment) mi_attr_noexcept {
+  return mi_heap_realloc_zero_aligned(heap,p,newsize,alignment,false);
+}
+
+void* mi_heap_rezalloc_aligned_at(mi_heap_t* heap, void* p, size_t newsize, size_t alignment, size_t offset) mi_attr_noexcept {
+  return mi_heap_realloc_zero_aligned_at(heap, p, newsize, alignment, offset, true);
+}
+
+void* mi_heap_rezalloc_aligned(mi_heap_t* heap, void* p, size_t newsize, size_t alignment) mi_attr_noexcept {
+  return mi_heap_realloc_zero_aligned(heap, p, newsize, alignment, true);
+}
+
+void* mi_heap_recalloc_aligned_at(mi_heap_t* heap, void* p, size_t newcount, size_t size, size_t alignment, size_t offset) mi_attr_noexcept {
+  size_t total;
+  if (mi_mul_overflow(newcount, size, &total)) return NULL;
+  return mi_heap_rezalloc_aligned_at(heap, p, total, alignment, offset);
+}
+
+void* mi_heap_recalloc_aligned(mi_heap_t* heap, void* p, size_t newcount, size_t size, size_t alignment) mi_attr_noexcept {
+  size_t total;
+  if (mi_mul_overflow(newcount, size, &total)) return NULL;
+  return mi_heap_rezalloc_aligned(heap, p, total, alignment);
+}
+
+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);
+}
+
+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);
+}
+
+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);
+}
+
+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);
+}
+
+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);
+}
+
+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);
+}
+