Metal: Fix FramebufferMtl's read-after-delete

src/libANGLE/renderer/metal/ContextMtl.h

@@ -363,6 +363,12 @@ class ContextMtl : public ContextImpl, public mtl::Context
     VertexArrayMtl *mVertexArray     = nullptr;
     ProgramMtl *mProgram             = nullptr;
 
+    // Special flag to indicate current draw framebuffer is default framebuffer.
+    // We need this instead of calling mDrawFramebuffer->getState().isDefault() because
+    // mDrawFramebuffer might point to a deleted object, ContextMtl only knows about this very late,
+    // only during syncState() function call.
+    bool mDrawFramebufferIsDefault = true;
+
     using DirtyBits = angle::BitSet<DIRTY_BIT_MAX>;
 
     gl::AttributesMask mDirtyDefaultAttribsMask;

src/libANGLE/renderer/metal/ContextMtl.mm

@@ -663,7 +663,7 @@ ProgramImpl *ContextMtl::createProgram(const gl::ProgramState &state)
 // Framebuffer creation
 FramebufferImpl *ContextMtl::createFramebuffer(const gl::FramebufferState &state)
 {
-    return new FramebufferMtl(state, false, false);
+    return new FramebufferMtl(state, false);
 }
 
 // Texture creation
@@ -937,9 +937,16 @@ void ContextMtl::present(const gl::Context *context, id<CAMetalDrawable> present
 {
     ensureCommandBufferValid();
 
-    if (hasStartedRenderPass(mDrawFramebuffer))
+    // Always discard default FBO's depth stencil buffers at the end of the frame:
+    if (mDrawFramebufferIsDefault && hasStartedRenderPass(mDrawFramebuffer))
     {
-        mDrawFramebuffer->onFinishedDrawingToFrameBuffer(context, &mRenderEncoder);
+        constexpr GLenum dsAttachments[] = {GL_DEPTH, GL_STENCIL};
+        (void)mDrawFramebuffer->invalidate(context, 2, dsAttachments);
+
+        endEncoding(false);
+
+        // Reset discard flag by notify framebuffer that a new render pass has started.
+        mDrawFramebuffer->onStartedDrawingToFrameBuffer(context);
     }
 
     endEncoding(false);
@@ -1172,14 +1179,10 @@ void ContextMtl::updateDrawFrameBufferBinding(const gl::Context *context)
 {
     const gl::State &glState = getState();
 
-    auto oldFrameBuffer = mDrawFramebuffer;
-
-    mDrawFramebuffer = mtl::GetImpl(glState.getDrawFramebuffer());
+    mDrawFramebuffer          = mtl::GetImpl(glState.getDrawFramebuffer());
+    mDrawFramebufferIsDefault = mDrawFramebuffer->getState().isDefault();
 
-    if (oldFrameBuffer && hasStartedRenderPass(oldFrameBuffer->getRenderPassDesc(this)))
-    {
-        oldFrameBuffer->onFinishedDrawingToFrameBuffer(context, &mRenderEncoder);
-    }
+    mDrawFramebuffer->onStartedDrawingToFrameBuffer(context);
 
     onDrawFrameBufferChange(context, mDrawFramebuffer);
 }

src/libANGLE/renderer/metal/FrameBufferMtl.h

@@ -24,9 +24,7 @@ class SurfaceMtl;
 class FramebufferMtl : public FramebufferImpl
 {
   public:
-    explicit FramebufferMtl(const gl::FramebufferState &state,
-                            bool flipY,
-                            bool alwaysDiscardDepthStencil);
+    explicit FramebufferMtl(const gl::FramebufferState &state, bool flipY);
     ~FramebufferMtl() override;
     void destroy(const gl::Context *context) override;
 
@@ -91,9 +89,8 @@ class FramebufferMtl : public FramebufferImpl
 
     const mtl::RenderPassDesc &getRenderPassDesc(ContextMtl *context);
 
-    // Call this to notify FramebufferMtl whenever its render pass has ended.
-    void onFinishedDrawingToFrameBuffer(const gl::Context *context,
-                                        mtl::RenderCommandEncoder *encoder);
+    // Call this to notify FramebufferMtl whenever its render pass has started.
+    void onStartedDrawingToFrameBuffer(const gl::Context *context);
 
     // The actual area will be adjusted based on framebuffer flipping property.
     gl::Rectangle getReadPixelArea(const gl::Rectangle &glArea);
@@ -140,13 +137,9 @@ class FramebufferMtl : public FramebufferImpl
     // depth & stencil attachments as of now. Separate depth & stencil could be useful to
     // save spaces on iOS devices. See doc/PackedDepthStencilSupport.md.
     std::array<RenderTargetMtl *, mtl::kMaxRenderTargets> mColorRenderTargets;
-    std::array<bool, mtl::kMaxRenderTargets> mDiscardColors;
     RenderTargetMtl *mDepthRenderTarget   = nullptr;
-    bool mDiscardDepth                    = false;
     RenderTargetMtl *mStencilRenderTarget = nullptr;
-    bool mDiscardStencil                  = false;
     mtl::RenderPassDesc mRenderPassDesc;
-    const bool mAlwaysDiscardDepthStencil;
     const bool mFlipY = false;
 };
 }  // namespace rx

src/libANGLE/renderer/metal/SurfaceMtl.mm

@@ -274,7 +274,7 @@ egl::Error SurfaceMtl::initialize(const egl::Display *display)
 FramebufferImpl *SurfaceMtl::createDefaultFramebuffer(const gl::Context *context,
                                                       const gl::FramebufferState &state)
 {
-    auto fbo = new FramebufferMtl(state, /* flipY */ true, /* alwaysDiscard */ true);
+    auto fbo = new FramebufferMtl(state, /* flipY */ true);
 
     return fbo;
 }

src/libANGLE/renderer/metal/mtl_command_buffer.h

@@ -236,6 +236,8 @@ class RenderCommandEncoder final : public CommandEncoder
 
     RenderCommandEncoder &setDepthStencilStoreAction(MTLStoreAction depthStoreAction,
                                                      MTLStoreAction stencilStoreAction);
+    RenderCommandEncoder &setDepthStoreAction(MTLStoreAction action);
+    RenderCommandEncoder &setStencilStoreAction(MTLStoreAction action);
 
     const RenderPassDesc &renderPassDesc() const { return mRenderPassDesc; }
 

src/libANGLE/renderer/metal/mtl_command_buffer.mm

@@ -753,6 +753,22 @@ RenderCommandEncoder &RenderCommandEncoder::setDepthStencilStoreAction(
     return *this;
 }
 
+RenderCommandEncoder &RenderCommandEncoder::setDepthStoreAction(MTLStoreAction action)
+{
+    // We only store the options, will defer the actual setting until the encoder finishes
+    mRenderPassDesc.depthAttachment.storeAction = action;
+
+    return *this;
+}
+
+RenderCommandEncoder &RenderCommandEncoder::setStencilStoreAction(MTLStoreAction action)
+{
+    // We only store the options, will defer the actual setting until the encoder finishes
+    mRenderPassDesc.stencilAttachment.storeAction = action;
+
+    return *this;
+}
+
 // BlitCommandEncoder
 BlitCommandEncoder::BlitCommandEncoder(CommandBuffer *cmdBuffer) : CommandEncoder(cmdBuffer, BLIT)
 {}

src/tests/gl_tests/DiscardFramebufferEXTTest.cpp

@@ -26,7 +26,10 @@ class DiscardFramebufferEXTTest : public ANGLETest
 
 TEST_P(DiscardFramebufferEXTTest, DefaultFramebuffer)
 {
-    ANGLE_SKIP_TEST_IF(!IsGLExtensionEnabled("EXT_discard_framebuffer"));
+    ANGLE_SKIP_TEST_IF(!IsGLExtensionEnabled("GL_EXT_discard_framebuffer"));
+
+    // TODO: fix crash issue. http://anglebug.com/4141
+    ANGLE_SKIP_TEST_IF(IsD3D11());
 
     // These should succeed on the default framebuffer
     const GLenum discards1[] = {GL_COLOR_EXT};
@@ -61,7 +64,7 @@ TEST_P(DiscardFramebufferEXTTest, DefaultFramebuffer)
 
 TEST_P(DiscardFramebufferEXTTest, NonDefaultFramebuffer)
 {
-    ANGLE_SKIP_TEST_IF(!IsGLExtensionEnabled("EXT_discard_framebuffer"));
+    ANGLE_SKIP_TEST_IF(!IsGLExtensionEnabled("GL_EXT_discard_framebuffer"));
 
     GLuint tex2D;
     GLuint framebuffer;