From 0929425477228bae5f134f2acf85a8ce6866fafb Mon Sep 17 00:00:00 2001
From: Dzmitry Malyshau <kvarkus@gmail.com>
Date: Wed, 1 Jul 2020 10:42:34 -0400
Subject: [PATCH] Require mapped buffers to be aligned

---
 wgpu-core/src/device/mod.rs   | 18 +++++++++++++-----
 wgpu-core/src/device/queue.rs |  2 +-
 2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/wgpu-core/src/device/mod.rs b/wgpu-core/src/device/mod.rs
index b4b9834686..5da3f44f50 100644
--- a/wgpu-core/src/device/mod.rs
+++ b/wgpu-core/src/device/mod.rs
@@ -22,10 +22,7 @@ use hal::{
     window::{PresentationSurface as _, Surface as _},
 };
 use parking_lot::{Mutex, MutexGuard};
-use wgt::{
-    BufferAddress, BufferSize, InputStepMode, TextureDimension, TextureFormat,
-    BIND_BUFFER_ALIGNMENT,
-};
+use wgt::{BufferAddress, BufferSize, InputStepMode, TextureDimension, TextureFormat};
 
 use std::{
     collections::hash_map::Entry, ffi, iter, marker::PhantomData, mem, ops::Range, ptr, slice,
@@ -670,6 +667,14 @@ impl<G: GlobalIdentityHandlerFactory> Global<G> {
 
         log::info!("Create buffer {:?} with ID {:?}", desc, id_in);
 
+        if desc.mapped_at_creation {
+            assert_eq!(
+                desc.size % wgt::COPY_BUFFER_ALIGNMENT,
+                0,
+                "Buffers that are mapped at creation have to be aligned to COPY_BUFFER_ALIGNMENT"
+            );
+        }
+
         let (device_guard, mut token) = hub.devices.read(&mut token);
         let device = &device_guard[device_id];
         let mut buffer = device.create_buffer(device_id, desc, gfx_memory::Kind::General);
@@ -1535,7 +1540,7 @@ impl<G: GlobalIdentityHandlerFactory> Global<G> {
                         };
 
                         assert_eq!(
-                            bb.offset % BIND_BUFFER_ALIGNMENT,
+                            bb.offset % wgt::BIND_BUFFER_ALIGNMENT,
                             0,
                             "Buffer offset {} must be a multiple of BIND_BUFFER_ALIGNMENT",
                             bb.offset
@@ -2792,6 +2797,9 @@ impl<G: GlobalIdentityHandlerFactory> Global<G> {
             HostMap::Write => (wgt::BufferUsage::MAP_WRITE, resource::BufferUse::MAP_WRITE),
         };
 
+        assert_eq!(range.start % wgt::COPY_BUFFER_ALIGNMENT, 0);
+        assert_eq!(range.end % wgt::COPY_BUFFER_ALIGNMENT, 0);
+
         let (device_id, ref_count) = {
             let (mut buffer_guard, _) = hub.buffers.write(&mut token);
             let buffer = &mut buffer_guard[buffer_id];
diff --git a/wgpu-core/src/device/queue.rs b/wgpu-core/src/device/queue.rs
index 2e1818e84b..1a7d4cadcc 100644
--- a/wgpu-core/src/device/queue.rs
+++ b/wgpu-core/src/device/queue.rs
@@ -188,7 +188,7 @@ impl<G: GlobalIdentityHandlerFactory> Global<G> {
             data_size % wgt::COPY_BUFFER_ALIGNMENT,
             0,
             "Buffer write size {} must be a multiple of {}",
-            buffer_offset,
+            data_size,
             wgt::COPY_BUFFER_ALIGNMENT,
         );
         assert_eq!(