From f37ae2d20eaf110378d6b9b6959a3ad6906d2d7d Mon Sep 17 00:00:00 2001
From: Belonit <54427022+Belonit@users.noreply.github.com>
Date: Mon, 31 Aug 2026 19:18:55 +0300
Subject: [PATCH] Fix bgfx backend allocation alignment

Define the required bx debug configuration and provide cache-line-aligned storage for bgfx render records.
---
 code/CMakeLists.txt  |  2 ++
 code/bgfxbackend.cpp | 28 ++++++++++++++++++++++++++++
 2 files changed, 30 insertions(+)

diff --git a/code/CMakeLists.txt b/code/CMakeLists.txt
index d7c705fb..8e90291c 100644
--- a/code/CMakeLists.txt
+++ b/code/CMakeLists.txt
@@ -163,6 +163,8 @@ set(BGFX_ROOT "${CMAKE_SOURCE_DIR}/thirdparty/bgfx.cmake/bgfx")
 set_source_files_properties("${CMAKE_CURRENT_SOURCE_DIR}/bgfxbackend.cpp" PROPERTIES
     INCLUDE_DIRECTORIES
         "${BGFX_ROOT}/include;${CMAKE_SOURCE_DIR}/thirdparty/bgfx.cmake/bx/include;${BGFX_ROOT}/examples/common/imgui"
+    COMPILE_DEFINITIONS
+        "BX_CONFIG_DEBUG=$<IF:$<CONFIG:Debug>,1,$<BOOL:${BX_CONFIG_DEBUG}>>"
     COMPILE_OPTIONS "/Zc:preprocessor"
 )
 
diff --git a/code/bgfxbackend.cpp b/code/bgfxbackend.cpp
index 2645ede6..3dc92567 100644
--- a/code/bgfxbackend.cpp
+++ b/code/bgfxbackend.cpp
@@ -15,15 +15,18 @@
 #include "dbgprint.h"
 #include "except.h"
 
+#include <bx/allocator.h>
 #include <bgfx/bgfx.h>
 #include <bgfx/embedded_shader.h>
 
 #include <vs_ocornut_imgui.bin.h>
 #include <fs_ocornut_imgui.bin.h>
 
+#include <algorithm>
 #include <cstdio>
 #include <cstdlib>
 #include <cstring>
+#include <malloc.h>
 
 
 static const bgfx::EmbeddedShader _EmbeddedShaders[] = {
@@ -119,6 +122,30 @@ class BackendCallback : public bgfx::CallbackI
 static BackendCallback _Callback;
 
 
+// bgfx contains cache-line-aligned render records but requests their backing arrays with
+// the allocator's default alignment. The Win32 CRT only guarantees eight-byte alignment,
+// which is insufficient when clang-cl copies those records with aligned SSE instructions.
+class BackendAllocator : public bx::AllocatorI
+{
+	public:
+		virtual ~BackendAllocator(void) override {}
+
+		virtual void * realloc(void * ptr, size_t size, size_t alignment, const char *, uint32_t) override
+		{
+			if (size == 0) {
+				_aligned_free(ptr);
+				return(NULL);
+			}
+
+			const size_t cachelinealignment = BX_CACHE_LINE_SIZE;
+			alignment = std::max(alignment, cachelinealignment);
+			return(_aligned_realloc(ptr, size, alignment));
+		}
+};
+
+static BackendAllocator _Allocator;
+
+
 /// <summary>
 /// Builds the table that widens a 565 pixel to the 32 bit color the fallback path uploads.
 /// </summary>
@@ -273,6 +300,7 @@ bool Backend_Init(HWND window, int windowwidth, int windowheight, BackendRendere
 	init.resolution.height = (uint32_t)windowheight;
 	init.resolution.reset = _ResetFlags;
 	init.callback = &_Callback;
+	init.allocator = &_Allocator;
 
 	switch (renderer) {
 		case BACKEND_RENDERER_D3D11: