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Gecko
5 Jun 2024 : Day 254 #
I'm continuing with my attempts to simplify the latest commit by removing unnecessary changes and doing my best to align the changes with the upstream ESR 91 changes.
To do this I've been looking carefully through the code to try to find unused methods that were added in my latest commit. I managed to find a couple. Both GLContext::ResizeOffscreen() and GLContext::OffscreenSize() have equivalents in the GLScreenBuffer class which can be used as drop-in replacements. So those two methods, which were previously added, are now added no more.
The other change I've made is to remove the following member variable from GLContext:
The other change I've made today is to simplify how the EGLDisplay is passed around when things are still being initialised. I'd created quite a web of methods to pass this between, with all of these needing this variable to be passed in. Here they are, with the aDisplay parameter at the end being the one I'd really like to avoid the need for.
After these changes the patch is still pretty large, but looking considerably better.
However, during my testing I hit another problem. It turns out that somewhere, some of the changes I made (probably related to offscreen rendering) have broken the WebGLContext capabilities. That means that if a web page uses WebGL it'll now trigger a crash. I know for sure that this was working earlier, so something has changed.
You'll have to forgive me for including a lengthy backtrace. I admit it's not very enlightening, but I want to keep a copy here so I have something to refer to. This is the backtrace for the crash:
So because I think it could be helpful in getting to the bottom of this, I'm also going to record how and where this surface is being created. Here's the backtrace for its creation:
Sadly I don't have the energy to dig into this crash further today, so I'll have to leave things there. I hope it won't be too hard to fix, but at this point it's already looking a bit tricky, so we'll have to see.
If you'd like to read any of my other gecko diary entries, they're all available on my Gecko-dev Diary page.
To do this I've been looking carefully through the code to try to find unused methods that were added in my latest commit. I managed to find a couple. Both GLContext::ResizeOffscreen() and GLContext::OffscreenSize() have equivalents in the GLScreenBuffer class which can be used as drop-in replacements. So those two methods, which were previously added, are now added no more.
The other change I've made is to remove the following member variable from GLContext:
std::map<GLuint, SharedSurface*> mFBOMappingWith this removed I'm also able to remove the related code from the source file as well as the dependency on the standard map header. I've tested the result and it doesn't seem to have any negative effects on either the browser or the WebView.
The other change I've made today is to simplify how the EGLDisplay is passed around when things are still being initialised. I'd created quite a web of methods to pass this between, with all of these needing this variable to be passed in. Here they are, with the aDisplay parameter at the end being the one I'd really like to avoid the need for.
RefPtr<GLLibraryEGL> DefaultEglLibrary(nsACString* const out_failureId,
EGLDisplay aDisplay);
inline std::shared_ptr<EglDisplay> DefaultEglDisplay(nsACString* const
out_failureId, EGLDisplay aDisplay);
RefPtr<GLLibraryEGL> GLLibraryEGL::Create(nsACString* const out_failureId,
EGLDisplay aDisplay);
bool GLLibraryEGL::Init(bool forceAccel, nsACString* const out_failureId,
EGLDisplay aDisplay);
Just by rearranging things a little I've been able to remove the aDisplay parameter from all of these. It turns out that most of them were just passing the value on to one of the other methods. Once they were taken away from one, they weren't needed in the others either.After these changes the patch is still pretty large, but looking considerably better.
However, during my testing I hit another problem. It turns out that somewhere, some of the changes I made (probably related to offscreen rendering) have broken the WebGLContext capabilities. That means that if a web page uses WebGL it'll now trigger a crash. I know for sure that this was working earlier, so something has changed.
You'll have to forgive me for including a lengthy backtrace. I admit it's not very enlightening, but I want to keep a copy here so I have something to refer to. This is the backtrace for the crash:
Thread 8 "GeckoWorkerThre" received signal SIGSEGV, Segmentation
fault.
[Switching to LWP 10166]
0x0000007ff28d1ca4 in mozilla::gl::SharedSurface_Basic::ToSurfaceDescriptor (
this=<optimized out>)
at gfx/gl/SharedSurfaceGL.cpp:38
38 MOZ_CRASH("GFX: ToSurfaceDescriptor");
(gdb) bt
#0 0x0000007ff28d1ca4 in mozilla::gl::SharedSurface_Basic::ToSurfaceDescriptor
(this=<optimized out>)
at gfx/gl/SharedSurfaceGL.cpp:38
#1 0x0000007ff36920a4 in mozilla::WebGLContext::GetFrontBuffer (
this=this@entry=0x7fc94889c0, xrFb=<optimized out>, webvr=webvr@entry=false)
at dom/canvas/WebGLContext.cpp:949
#2 0x0000007ff365a410 in mozilla::HostWebGLContext::GetFrontBuffer (
this=<optimized out>, xrFb=<optimized out>, webvr=false)
at ${PROJECT}/obj-build-mer-qt-xr/dist/include/mozilla/RefPtr.h:280
#3 0x0000007ff365a4c0 in mozilla::ClientWebGLContext::GetFrontBuffer (
this=this@entry=0x7fc8b48ec0, fb=fb@entry=0x0, vr=<optimized out>,
vr@entry=false)
at dom/canvas/ClientWebGLContext.cpp:373
#4 0x0000007ff29b0084 in mozilla::layers::ShareableCanvasRenderer::<lambda()>::
operator() (__closure=<synthetic pointer>)
at gfx/layers/ShareableCanvasRenderer.cpp:148
#5 mozilla::layers::ShareableCanvasRenderer::UpdateCompositableClient (
this=0x7fc96d7db0)
at gfx/layers/ShareableCanvasRenderer.cpp:195
#6 0x0000007ff29efa84 in mozilla::layers::ClientCanvasLayer::RenderLayer (
this=0x7fc978af90)
at gfx/layers/client/ClientCanvasLayer.cpp:25
#7 0x0000007ff29eeba4 in mozilla::layers::ClientLayer::RenderLayerWithReadback
(this=<optimized out>, aReadback=<optimized out>)
at gfx/layers/client/ClientLayerManager.h:365
#8 0x0000007ff29feeec in mozilla::layers::ClientContainerLayer::RenderLayer (
this=0x7fc978a680)
at gfx/layers/Layers.h:1051
#9 0x0000007ff29eeba4 in mozilla::layers::ClientLayer::RenderLayerWithReadback
(this=<optimized out>, aReadback=<optimized out>)
at gfx/layers/client/ClientLayerManager.h:365
#10 0x0000007ff29feeec in mozilla::layers::ClientContainerLayer::RenderLayer (
this=0x7fc9424e20)
at gfx/layers/Layers.h:1051
#11 0x0000007ff29eeba4 in mozilla::layers::ClientLayer::RenderLayerWithReadback
(this=<optimized out>, aReadback=<optimized out>)
at gfx/layers/client/ClientLayerManager.h:365
#12 0x0000007ff29feeec in mozilla::layers::ClientContainerLayer::RenderLayer (
this=0x7fc8dd8d50)
at gfx/layers/Layers.h:1051
#13 0x0000007ff2a05bd0 in mozilla::layers::ClientLayerManager::
EndTransactionInternal (this=this@entry=0x7fc8b17440,
aCallback=aCallback@entry=
0x7ff46a23d0 <mozilla::FrameLayerBuilder::DrawPaintedLayer(mozilla::layers::
PaintedLayer*, gfxContext*, mozilla::gfx::IntRegionTyped<mozilla::gfx::
UnknownUnits> const&, mozilla::gfx::IntRegionTyped<mozilla::gfx::
UnknownUnits> const&, mozilla::layers::DrawRegionClip, mozilla::gfx::
IntRegionTyped<mozilla::gfx::UnknownUnits> const&, void*)>,
aCallbackData=aCallbackData@entry=0x7fdf293268)
at gfx/layers/client/ClientLayerManager.cpp:341
#14 0x0000007ff2a10ad0 in mozilla::layers::ClientLayerManager::EndTransaction (
this=0x7fc8b17440,
aCallback=0x7ff46a23d0 <mozilla::FrameLayerBuilder::DrawPaintedLayer(
mozilla::layers::PaintedLayer*, gfxContext*, mozilla::gfx::
IntRegionTyped<mozilla::gfx::UnknownUnits> const&, mozilla::gfx::
IntRegionTyped<mozilla::gfx::UnknownUnits> const&, mozilla::layers::
DrawRegionClip, mozilla::gfx::IntRegionTyped<mozilla::gfx::UnknownUnits>
const&, void*)>, aCallbackData=0x7fdf293268, aFlags=mozilla::layers::
LayerManager::END_DEFAULT)
at gfx/layers/client/ClientLayerManager.cpp:397
#15 0x0000007ff469f7f0 in nsDisplayList::PaintRoot (
this=this@entry=0x7fdf295078, aBuilder=aBuilder@entry=0x7fdf293268,
aCtx=aCtx@entry=0x0,
aFlags=aFlags@entry=13, aDisplayListBuildTime=...)
at layout/painting/nsDisplayList.cpp:2622
#16 0x0000007ff442bb4c in nsLayoutUtils::PaintFrame (
aRenderingContext=aRenderingContext@entry=0x0,
aFrame=aFrame@entry=0x7fc932f550, aDirtyRegion=...,
aBackstop=aBackstop@entry=4294967295,
aBuilderMode=aBuilderMode@entry=nsDisplayListBuilderMode::Painting,
aFlags=aFlags@entry=(nsLayoutUtils::PaintFrameFlags::WidgetLayers |
nsLayoutUtils::PaintFrameFlags::ExistingTransaction | nsLayoutUtils::
PaintFrameFlags::NoComposite)) at ${PROJECT}/obj-build-mer-qt-xr/dist/
include/mozilla/MaybeStorageBase.h:80
#17 0x0000007ff43b6240 in mozilla::PresShell::Paint (
this=this@entry=0x7fc92a8a70, aViewToPaint=aViewToPaint@entry=0x7fc9287140,
aDirtyRegion=...,
aFlags=aFlags@entry=mozilla::PaintFlags::PaintLayers)
at layout/base/PresShell.cpp:6400
#18 0x0000007ff41ee110 in nsViewManager::ProcessPendingUpdatesPaint (
this=this@entry=0x7fc92870d0, aWidget=aWidget@entry=0x7fc92871c0)
at ${PROJECT}/obj-build-mer-qt-xr/dist/include/mozilla/gfx/RectAbsolute.h:43
[...]
#51 0x0000007fefba989c in ?? () from /lib64/libc.so.6
(gdb)
Reading through just the first few items in this backtrace, it's clear that the reason is due to the call to SharedSurface_Basic::ToSurfaceDescriptor(), which is intentionally triggering a crash based on the code that's there. Given this, it's possible the problem is that the SharedSurface_Basic object that's being used should have been one of the several other alternative surface variants.So because I think it could be helpful in getting to the bottom of this, I'm also going to record how and where this surface is being created. Here's the backtrace for its creation:
#0 mozilla::gl::SharedSurface_Basic::SharedSurface_Basic (this=0x7fc8d77e40,
gl=0x7fc97f9830, size=..., hasAlpha=false, tex=1, ownsTex=true)
at gfx/gl/SharedSurfaceGL.cpp:78
#1 0x0000007ff28d3e6c in mozilla::gl::SharedSurface_Basic::Create (
gl=0x7fc97f9830, formats=..., size=..., hasAlpha=false)
at ${PROJECT}/obj-build-mer-qt-xr/dist/include/mozilla/cxxalloc.h:33
#2 0x0000007ff28a3720 in mozilla::gl::SurfaceFactory_Basic::CreateSharedImpl (
this=<optimized out>, desc=...)
at ${PROJECT}/obj-build-mer-qt-xr/dist/include/mozilla/WeakPtr.h:185
#3 0x0000007ff28a3628 in mozilla::gl::SurfaceFactory::CreateShared (
this=0x7fc93e17c0, size=...)
at ${PROJECT}/obj-build-mer-qt-xr/dist/include/mozilla/RefCounted.h:240
#4 0x0000007ff28a5f24 in mozilla::gl::SwapChain::Acquire (
this=this@entry=0x7fc92ed298, size=...)
at ${PROJECT}/obj-build-mer-qt-xr/dist/include/mozilla/UniquePtr.h:290
#5 0x0000007ff369bed4 in mozilla::WebGLContext::PresentInto (
this=this@entry=0x7fc92ece00, swapChain=...)
at ${PROJECT}/obj-build-mer-qt-xr/dist/include/mozilla/UniquePtr.h:290
#6 0x0000007ff369c304 in mozilla::WebGLContext::Present (
this=this@entry=0x7fc92ece00, xrFb=<optimized out>,
consumerType=consumerType@entry=mozilla::layers::TextureType::Unknown,
webvr=webvr@entry=false)
at dom/canvas/WebGLContext.cpp:936
#7 0x0000007ff3664300 in mozilla::HostWebGLContext::Present (webvr=false,
t=mozilla::layers::TextureType::Unknown, xrFb=<optimized out>,
this=<optimized out>) at ${PROJECT}/obj-build-mer-qt-xr/dist/include/
mozilla/RefPtr.h:280
#8 mozilla::ClientWebGLContext::Run<void (mozilla::HostWebGLContext::*)(
unsigned long, mozilla::layers::TextureType, bool) const, &(mozilla::
HostWebGLContext::Present(unsigned long, mozilla::layers::TextureType,
bool) const), unsigned long, mozilla::layers::TextureType const&, bool
const&> (
this=<optimized out>, args#0=@0x7fdf2926c0: 0, args#1=@0x7fdf2926bf:
mozilla::layers::TextureType::Unknown, args#2=@0x7fdf2926be: false)
at dom/canvas/ClientWebGLContext.cpp:313
#9 0x0000007ff3664468 in mozilla::ClientWebGLContext::Present (
this=this@entry=0x7fc9558160, xrFb=xrFb@entry=0x0, type=<optimized out>,
webvr=<optimized out>, webvr@entry=false)
at dom/canvas/ClientWebGLContext.cpp:363
#10 0x0000007ff368fc78 in mozilla::ClientWebGLContext::OnBeforePaintTransaction
(this=0x7fc9558160)
at dom/canvas/ClientWebGLContext.cpp:345
#11 0x0000007ff28ff0dc in mozilla::layers::CanvasRenderer::
FirePreTransactionCallback (this=this@entry=0x7fc9646e50)
at gfx/layers/CanvasRenderer.cpp:75
#12 0x0000007ff29afee8 in mozilla::layers::ShareableCanvasRenderer::
UpdateCompositableClient (this=0x7fc9646e50)
at gfx/layers/ShareableCanvasRenderer.cpp:192
#13 0x0000007ff29efa84 in mozilla::layers::ClientCanvasLayer::RenderLayer (
this=0x7fc98f02c0)
at gfx/layers/client/ClientCanvasLayer.cpp:25
#14 0x0000007ff29eeba4 in mozilla::layers::ClientLayer::RenderLayerWithReadback
(this=<optimized out>, aReadback=<optimized out>)
at gfx/layers/client/ClientLayerManager.h:365
#15 0x0000007ff29feeec in mozilla::layers::ClientContainerLayer::RenderLayer (
this=0x7fc991a8d0)
at gfx/layers/Layers.h:1051
#16 0x0000007ff29eeba4 in mozilla::layers::ClientLayer::RenderLayerWithReadback
(this=<optimized out>, aReadback=<optimized out>)
at gfx/layers/client/ClientLayerManager.h:365
#17 0x0000007ff29feeec in mozilla::layers::ClientContainerLayer::RenderLayer (
this=0x7fc935acd0)
at gfx/layers/Layers.h:1051
#18 0x0000007ff29eeba4 in mozilla::layers::ClientLayer::RenderLayerWithReadback
(this=<optimized out>, aReadback=<optimized out>)
at gfx/layers/client/ClientLayerManager.h:365
#19 0x0000007ff29feeec in mozilla::layers::ClientContainerLayer::RenderLayer (
this=0x7fc8d8f2f0)
at gfx/layers/Layers.h:1051
#20 0x0000007ff2a05bd0 in mozilla::layers::ClientLayerManager::
EndTransactionInternal (this=this@entry=0x7fc8b17e40,
aCallback=aCallback@entry=
0x7ff46a23d0 <mozilla::FrameLayerBuilder::DrawPaintedLayer(mozilla::layers::
PaintedLayer*, gfxContext*, mozilla::gfx::IntRegionTyped<mozilla::gfx::
UnknownUnits> const&, mozilla::gfx::IntRegionTyped<mozilla::gfx::
UnknownUnits> const&, mozilla::layers::DrawRegionClip, mozilla::gfx::
IntRegionTyped<mozilla::gfx::UnknownUnits> const&, void*)>,
aCallbackData=aCallbackData@entry=0x7fdf293268)
at gfx/layers/client/ClientLayerManager.cpp:341
#21 0x0000007ff2a10ad0 in mozilla::layers::ClientLayerManager::EndTransaction (
this=0x7fc8b17e40,
aCallback=0x7ff46a23d0 <mozilla::FrameLayerBuilder::DrawPaintedLayer(
mozilla::layers::PaintedLayer*, gfxContext*, mozilla::gfx::
IntRegionTyped<mozilla::gfx::UnknownUnits> const&, mozilla::gfx::
IntRegionTyped<mozilla::gfx::UnknownUnits> const&, mozilla::layers::
DrawRegionClip, mozilla::gfx::IntRegionTyped<mozilla::gfx::UnknownUnits>
const&, void*)>, aCallbackData=0x7fdf293268, aFlags=mozilla::layers::
LayerManager::END_DEFAULT)
at gfx/layers/client/ClientLayerManager.cpp:397
#22 0x0000007ff469f7f0 in nsDisplayList::PaintRoot (
this=this@entry=0x7fdf295078, aBuilder=aBuilder@entry=0x7fdf293268,
aCtx=aCtx@entry=0x0,
aFlags=aFlags@entry=13, aDisplayListBuildTime=...)
at layout/painting/nsDisplayList.cpp:2622
#23 0x0000007ff442bb4c in nsLayoutUtils::PaintFrame (
aRenderingContext=aRenderingContext@entry=0x0,
aFrame=aFrame@entry=0x7fc93240a0, aDirtyRegion=...,
aBackstop=aBackstop@entry=4294967295,
aBuilderMode=aBuilderMode@entry=nsDisplayListBuilderMode::Painting,
aFlags=aFlags@entry=(nsLayoutUtils::PaintFrameFlags::WidgetLayers |
nsLayoutUtils::PaintFrameFlags::ExistingTransaction | nsLayoutUtils::
PaintFrameFlags::NoComposite)) at ${PROJECT}/obj-build-mer-qt-xr/dist/
include/mozilla/MaybeStorageBase.h:80
#24 0x0000007ff43b6240 in mozilla::PresShell::Paint (
this=this@entry=0x7fc9295080, aViewToPaint=aViewToPaint@entry=0x7fc9273470,
aDirtyRegion=...,
aFlags=aFlags@entry=mozilla::PaintFlags::PaintLayers)
at layout/base/PresShell.cpp:6400
#25 0x0000007ff41ee110 in nsViewManager::ProcessPendingUpdatesPaint (
this=this@entry=0x7fc9273430, aWidget=aWidget@entry=0x7fc92734f0)
at ${PROJECT}/obj-build-mer-qt-xr/dist/include/mozilla/gfx/RectAbsolute.h:43
[...]
#58 0x0000007fefba989c in ?? () from /lib64/libc.so.6
(gdb)
Again, apologies for the lengthy backtraces. I'm not going to try to debug and fix this today, so I'm thinking it might be helpful to have these backtraces as something to refer back to for the future.Sadly I don't have the energy to dig into this crash further today, so I'll have to leave things there. I hope it won't be too hard to fix, but at this point it's already looking a bit tricky, so we'll have to see.
If you'd like to read any of my other gecko diary entries, they're all available on my Gecko-dev Diary page.
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