--- /dev/null
+From 0240fd6d0f7e27c459b243578ad51100ff6e2b66 Mon Sep 17 00:00:00 2001
+From: Jan Palus <jpalus@fastmail.com>
+Date: Wed, 5 Oct 2022 00:18:09 +0200
+Subject: [PATCH 1/2] fix(memory): fix memory alignment for dynamic allocation
+
+all pointers returned by arena_alloc residing in arena block should be
+properly aligned
+
+to meet neovim's alignment requirements but keeping it simple settle on
+ARENA_ALIGN = MAX(sizeof(void *), sizeof(double)).
+---
+ src/nvim/memory.c | 32 +++++++++++++++++++-------------
+ src/nvim/memory.h | 2 +-
+ 2 files changed, 20 insertions(+), 14 deletions(-)
+
+diff --git a/src/nvim/memory.c b/src/nvim/memory.c
+index 61c43d8f995a..93aa9bd6e55e 100644
+--- a/src/nvim/memory.c
++++ b/src/nvim/memory.c
+@@ -6,6 +6,7 @@
+ #include <assert.h>
+ #include <inttypes.h>
+ #include <stdbool.h>
++#include <stdint.h>
+ #include <string.h>
+
+ #include "nvim/api/extmark.h"
+@@ -576,6 +577,12 @@ void alloc_block(Arena *arena)
+ blk->prev = prev_blk;
+ }
+
++static size_t arena_align_offset(void *ptr, size_t alignment)
++{
++ uintptr_t uptr = (uintptr_t)ptr;
++ return ((uptr + (alignment - 1)) & ~(alignment - 1)) - uptr;
++}
++
+ /// @param arena if NULL, do a global allocation. caller must then free the value!
+ /// @param size if zero, will still return a non-null pointer, but not a unique one
+ void *arena_alloc(Arena *arena, size_t size, bool align)
+@@ -583,34 +590,33 @@ void *arena_alloc(Arena *arena, size_t size, bool align)
+ if (!arena) {
+ return xmalloc(size);
+ }
+- if (align) {
+- arena->pos = (arena->pos + (ARENA_ALIGN - 1)) & ~(ARENA_ALIGN - 1);
++ if (!arena->cur_blk) {
++ alloc_block(arena);
+ }
+- if (arena->pos + size > arena->size || !arena->cur_blk) {
+- if (size > (ARENA_BLOCK_SIZE - sizeof(struct consumed_blk)) >> 1) {
++ size_t align_pos = align ? arena_align_offset(arena->cur_blk + arena->pos, ARENA_ALIGN) : 0;
++ if (arena->pos + align_pos + size > arena->size) {
++ if (size + (align ? (ARENA_ALIGN - 1) : 0) > (ARENA_BLOCK_SIZE - sizeof(struct consumed_blk))
++ >> 1) {
+ // if allocation is too big, allocate a large block with the requested
+ // size, but still with block pointer head. We do this even for
+ // arena->size / 2, as there likely is space left for the next
+ // small allocation in the current block.
+- if (!arena->cur_blk) {
+- // to simplify free-list management, arena->cur_blk must
+- // always be a normal, ARENA_BLOCK_SIZE sized, block
+- alloc_block(arena);
+- }
+ arena_alloc_count++;
+- char *alloc = xmalloc(size + sizeof(struct consumed_blk));
++ char *alloc = xmalloc(size + sizeof(struct consumed_blk) + (align ? (ARENA_ALIGN - 1) : 0));
+ struct consumed_blk *cur_blk = (struct consumed_blk *)arena->cur_blk;
+ struct consumed_blk *fix_blk = (struct consumed_blk *)alloc;
+ fix_blk->prev = cur_blk->prev;
+ cur_blk->prev = fix_blk;
+- return (alloc + sizeof(struct consumed_blk));
++ char *mem = (alloc + sizeof(struct consumed_blk));
++ return mem + (align ? arena_align_offset(mem, ARENA_ALIGN) : 0);
+ } else {
+ alloc_block(arena);
++ align_pos = align ? arena_align_offset(arena->cur_blk + arena->pos, ARENA_ALIGN) : 0;
+ }
+ }
+
+- char *mem = arena->cur_blk + arena->pos;
+- arena->pos += size;
++ char *mem = arena->cur_blk + arena->pos + align_pos;
++ arena->pos += (size + align_pos);
+ return mem;
+ }
+
+diff --git a/src/nvim/memory.h b/src/nvim/memory.h
+index f40719233165..1c2ed2ba3b20 100644
+--- a/src/nvim/memory.h
++++ b/src/nvim/memory.h
+@@ -45,7 +45,7 @@ typedef struct consumed_blk {
+ struct consumed_blk *prev;
+ } *ArenaMem;
+
+-#define ARENA_ALIGN sizeof(void *)
++#define ARENA_ALIGN MAX(sizeof(void *), sizeof(double))
+
+ typedef struct {
+ char *cur_blk;
+
+From 8b7247af7dc613a7e4248ba14760f586a8a66a32 Mon Sep 17 00:00:00 2001
+From: bfredl <bjorn.linse@gmail.com>
+Date: Mon, 31 Oct 2022 10:07:21 +0100
+Subject: [PATCH 2/2] refactor(memory): simplify new alignment logic
+
+In particular, we can assume the xmalloc-ed pointer is at least
+double-aligned, otherwise nothing work work.
+---
+ src/nvim/memory.c | 32 +++++++++++++++++---------------
+ 1 file changed, 17 insertions(+), 15 deletions(-)
+
+diff --git a/src/nvim/memory.c b/src/nvim/memory.c
+index 93aa9bd6e55e..16033e9c63f5 100644
+--- a/src/nvim/memory.c
++++ b/src/nvim/memory.c
+@@ -577,14 +577,13 @@ void alloc_block(Arena *arena)
+ blk->prev = prev_blk;
+ }
+
+-static size_t arena_align_offset(void *ptr, size_t alignment)
++static size_t arena_align_offset(uint64_t off)
+ {
+- uintptr_t uptr = (uintptr_t)ptr;
+- return ((uptr + (alignment - 1)) & ~(alignment - 1)) - uptr;
++ return ((off + (ARENA_ALIGN - 1)) & ~(ARENA_ALIGN - 1));
+ }
+
+ /// @param arena if NULL, do a global allocation. caller must then free the value!
+-/// @param size if zero, will still return a non-null pointer, but not a unique one
++/// @param size if zero, will still return a non-null pointer, but not a usable or unique one
+ void *arena_alloc(Arena *arena, size_t size, bool align)
+ {
+ if (!arena) {
+@@ -593,30 +592,33 @@ void *arena_alloc(Arena *arena, size_t size, bool align)
+ if (!arena->cur_blk) {
+ alloc_block(arena);
+ }
+- size_t align_pos = align ? arena_align_offset(arena->cur_blk + arena->pos, ARENA_ALIGN) : 0;
+- if (arena->pos + align_pos + size > arena->size) {
+- if (size + (align ? (ARENA_ALIGN - 1) : 0) > (ARENA_BLOCK_SIZE - sizeof(struct consumed_blk))
+- >> 1) {
++ size_t alloc_pos = align ? arena_align_offset(arena->pos) : arena->pos;
++ if (alloc_pos + size > arena->size) {
++ if (size > (ARENA_BLOCK_SIZE - sizeof(struct consumed_blk)) >> 1) {
+ // if allocation is too big, allocate a large block with the requested
+ // size, but still with block pointer head. We do this even for
+ // arena->size / 2, as there likely is space left for the next
+ // small allocation in the current block.
+ arena_alloc_count++;
+- char *alloc = xmalloc(size + sizeof(struct consumed_blk) + (align ? (ARENA_ALIGN - 1) : 0));
++ size_t hdr_size = sizeof(struct consumed_blk);
++ size_t aligned_hdr_size = (align ? arena_align_offset(hdr_size) : hdr_size);
++ char *alloc = xmalloc(size + aligned_hdr_size);
++
++ // to simplify free-list management, arena->cur_blk must
++ // always be a normal, ARENA_BLOCK_SIZE sized, block
+ struct consumed_blk *cur_blk = (struct consumed_blk *)arena->cur_blk;
+ struct consumed_blk *fix_blk = (struct consumed_blk *)alloc;
+ fix_blk->prev = cur_blk->prev;
+ cur_blk->prev = fix_blk;
+- char *mem = (alloc + sizeof(struct consumed_blk));
+- return mem + (align ? arena_align_offset(mem, ARENA_ALIGN) : 0);
++ return alloc + aligned_hdr_size;
+ } else {
+- alloc_block(arena);
+- align_pos = align ? arena_align_offset(arena->cur_blk + arena->pos, ARENA_ALIGN) : 0;
++ alloc_block(arena); // resets arena->pos
++ alloc_pos = align ? arena_align_offset(arena->pos) : arena->pos;
+ }
+ }
+
+- char *mem = arena->cur_blk + arena->pos + align_pos;
+- arena->pos += (size + align_pos);
++ char *mem = arena->cur_blk + alloc_pos;
++ arena->pos = alloc_pos + size;
+ return mem;
+ }
+
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