peterwmwong / argumentbufferxcodecrashrepro

XCode Crash with Metal Arguments Buffer Repro

Attempting to use an Arguments Buffer (SceneArgumentBuffer) containing a pointer (array) of Rectangle causes XCode Frame Capture to crash.

Crashed Thread:        24  Dispatch queue: gputools.GPUMTLVariablesViewContentProvider.0x2d0638a40

Exception Type:        EXC_BAD_ACCESS (SIGSEGV)
Exception Codes:       KERN_INVALID_ADDRESS at 0x0000000000000a10
Exception Codes:       0x0000000000000001, 0x0000000000000a10
Exception Note:        EXC_CORPSE_NOTIFY

Snippets of Arguments Buffer usage

Common code

// File: AAPLShaderTypes.h
// -----------------------
typedef struct Rectangle
{
    vector_float4 color;
    vector_float2 size;
} Rectangle;

Vertex Shader code

// File: AAPLShaders.metal
// -----------------------
struct SceneArgumentBuffer {
    device Rectangle *rects [[ id(SceneArgumentBufferIDRectangles) ]];
};

vertex VertexOut
vertexShader(         uint                 instanceID [[ instance_id ]],
                      uint                 vertexID   [[ vertex_id ]],
             constant SceneArgumentBuffer &args       [[ buffer(VertexBufferIndexArgumentBuffer) ]])
{
    // ...
}

Renderer code

// File: AAPLShaderTypes.h
// -----------------------

// Nested buffer (Array of Rectangle structs)
uint16_t numRects = 2;
_rectanglesBuffer = [_device newBufferWithLength:sizeof(Rectangle) * numRects
                                            options:MTLResourceStorageModeShared];
_rectanglesBuffer.label = @"Rects Buffer";

Rectangle * const rects = _rectanglesBuffer.contents;
rects[0].color = simd_make_float4(0.0, 1.0, 0.0, 1.0);
rects[0].size  = simd_make_float2(0.75, 0.75);

rects[1].color = simd_make_float4(0.0, 0.0, 1.0, 1.0);
rects[1].size  = simd_make_float2(0.5, 0.25);

// Argument buffer creation and encoding
id<MTLArgumentEncoder> argumentEncoder =
    [vertexFunction newArgumentEncoderWithBufferIndex:VertexBufferIndexArgumentBuffer];
_argumentBuffer = [_device newBufferWithLength:argumentEncoder.encodedLength options:0];
_argumentBuffer.label = @"Argument Buffer";
[argumentEncoder setArgumentBuffer:_argumentBuffer
                            offset:0];
[argumentEncoder setBuffer:_rectanglesBuffer
                    offset:0
                    atIndex:SceneArgumentBufferIDRectangles];

// Encoding into a Render Command
id<MTLRenderCommandEncoder> renderEncoder = [commandBuffer renderCommandEncoderWithDescriptor:renderPassDescriptor];
[renderEncoder useResource:_rectanglesBuffer
                     usage:MTLResourceUsageRead
                    stages:MTLRenderStageVertex];
[renderEncoder setVertexBuffer:_argumentBuffer
                        offset:0
                       atIndex:VertexBufferIndexArgumentBuffer];

Reproduction Steps

1. git clone this repository

   git clone [email protected]:peterwmwong/ArgumentBufferXCodeCrashRepro.git

2. Open project in XCode
3. Update Project settings to assign team
   • "Signing & Capabilities" -> "Signing" -> "Team"
4. Build / Run
5. Verify application window appears and 2 overlapping rectangles appear (green and blue).
6. In XCode, Capture GPU Workload
7. In the Debug navigator sidebar, navigate and select the only draw render command
   • MyCommand -> MyRenderEncoder -> [drawPrimitives: ...]
8. Notice XCode crashes with a similar looking report...

   Process:               Xcode [28558]
   Path:                  /Applications/Xcode.app/Contents/MacOS/Xcode
   Identifier:            com.apple.dt.Xcode
   Version:               13.2 (19585)
   Build Info:            IDEFrameworks-19585000000000000~2 (13C90)
   Code Type:             ARM-64 (Native)
   Parent Process:        launchd [1]
   User ID:               501
   
   Date/Time:             2022-03-10 12:33:57.8934 -0600
   OS Version:            macOS 12.2.1 (21D62)
   Report Version:        12
   Anonymous UUID:        9B84779D-936D-99F7-788A-C88BA5F20B46
   
   Sleep/Wake UUID:       E0F868C8-9471-44EF-9B92-B523178F0A9C
   
   Time Awake Since Boot: 33000 seconds
   Time Since Wake:       7694 seconds
   
   System Integrity Protection: enabled
   
   Crashed Thread:        24  Dispatch queue: gputools.GPUMTLVariablesViewContentProvider.0x2d0638a40
   
   Exception Type:        EXC_BAD_ACCESS (SIGSEGV)
   Exception Codes:       KERN_INVALID_ADDRESS at 0x0000000000000a10
   Exception Codes:       0x0000000000000001, 0x0000000000000a10
   Exception Note:        EXC_CORPSE_NOTIFY
   
   Termination Reason:    Namespace SIGNAL, Code 11 Segmentation fault: 11
   Terminating Process:   exc handler [28558]
   
   VM Region Info: 0xa10 is not in any region.  Bytes before following region: 4374443504
       REGION TYPE                    START - END         [ VSIZE] PRT/MAX SHRMOD  REGION DETAIL
       UNUSED SPACE AT START
   --->  
       __TEXT                      104bcc000-104bd0000    [   16K] r-x/r-x SM=COW  ...s/MacOS/Xcode
   

Screen recordings

Using Arguments Buffer (crash)

MOV video

NOT using Arguments Buffer (no crash)

MOV video

Enable/Disable using Arguments Buffer

• Open AAPLShaderTypes.h
• Enable using Arguments Buffer...

  #define USE_ARGUMENTS_BUFFER
  //#undef USE_ARGUMENTS_BUFFER

• Disable using Arguments Buffer...

  //#define USE_ARGUMENTS_BUFFER
  #undef USE_ARGUMENTS_BUFFER