assertion failed: !needs_clipping || batch.key.blend_mode == BlendMode::Alpha || batch.key.blend_mode == BlendMode::PremultipliedAlpha

[behnam]

On a dev build on master (81f273b), I get the following failed assertion:

$ ./mach run https://www.google.com?hl=ar
assertion failed: !needs_clipping || batch.key.blend_mode == BlendMode::Alpha ||
    batch.key.blend_mode == BlendMode::PremultipliedAlpha (thread main, at /Users/behnam/code/rust/servo/.cargo/git/checkouts/webrender-c3596abe1cf4f320/005eb39/webrender/src/renderer.rs:1506)
stack backtrace:
   0:        0x1092c0bb4 - backtrace::backtrace::trace::hc04eef90157d46bd
   1:        0x1092b932f - backtrace::capture::Backtrace::new::h5e598cddffa26117
   2:        0x1057f2296 - servo::main::_$u7b$$u7b$closure$u7d$$u7d$::hdae71a2e43b7d51b
   3:        0x10aba0e96 - std::panicking::rust_panic_with_hook::h2bd2f0b446f0face
                        at src/libstd/panicking.rs:550
   4:        0x1097010a5 - std::panicking::begin_panic::haf2b6374444f377d
   5:        0x109908b82 - webrender::renderer::Renderer::submit_batch::h65aed72e2f129087
   6:        0x10990b357 - webrender::renderer::Renderer::draw_color_target::h4a7df30d0748463e
   7:        0x10990d3ff - webrender::renderer::Renderer::draw_tile_frame::h23c3f6eb38d120fc
   8:        0x109905eb2 - webrender::renderer::Renderer::render::_$u7b$$u7b$closure$u7d$$u7d$::he5d9d628762261da
   9:        0x1098dd755 - webrender::profiler::TimeProfileCounter::profile::h75b84045babc7abe
  10:        0x10990587b - webrender::renderer::Renderer::render::h774b8d7d420477a3
  11:        0x10585584d - _$LT$compositing..compositor..IOCompositor$LT$Window$GT$$GT$::composite_specific_target::_$u7b$$u7b$closure$u7d$$u7d$::h4fea5509359fd135
  12:        0x105832512 - profile_traits::time::profile::h854a098829aaea4b
  13:        0x10579bbee - compositing::compositor::{{impl}}::composite_specific_target<glutin_app::window::Window>
                        at /Users/behnam/code/rust/servo/components/compositing/compositor.rs:1522
  14:        0x1057a1b0f - compositing::compositor::{{impl}}::composite<glutin_app::window::Window>
                        at /Users/behnam/code/rust/servo/components/compositing/compositor.rs:1466
  15:        0x105792f91 - compositing::compositor::{{impl}}::handle_events<glutin_app::window::Window>
                        at /Users/behnam/code/rust/servo/components/compositing/compositor.rs:1681
  16:        0x1057b3a3a - _$LT$servo..Browser$LT$Window$GT$$GT$::handle_events::h357f2c928362d20f
  17:        0x1057f198a - servo::main::h50470fc599e5d400
  18:        0x10aba1ffa - __rust_maybe_catch_panic
                        at src/libpanic_unwind/lib.rs:98
  19:        0x10aba12c1 - std::rt::lang_start::hbda94898b2b88ae4
                        at src/libstd/rt.rs:57
  20:        0x1057f2829 - main
ERROR:servo: assertion failed: !needs_clipping || batch.key.blend_mode == BlendMode::Alpha ||
    batch.key.blend_mode == BlendMode::PremultipliedAlpha
Servo exited with return value 101

System: macOS/MacPorts
rustc 1.17.0 (56124baa9 2017-04-24)
cargo 0.18.0 (fe7b0cdcf 2017-04-24)

[jdm]

cc @glennw

[cbrewster]

I am also hitting this panic whenever running browser.html ./mach run -d -b

[jdm]

I reproduce this on reddit.com.

[jdm]

(lldb) p batch.key
(webrender::tiling::AlphaBatchKey) $0 = AlphaBatchKey {
kind: TextRun,
flags: AlphaBatchKeyFlags {
bits: '\x03'
},
blend_mode: Subpixel(ColorF {
r: 0,
g: 0,
b: 0,
a: 1
}),
textures: BatchTextures {
colors: [TextureCache(CacheTextureId(0)), Invalid, Invalid]
}
}

[jdm]

(lldb) p *batch
(webrender::tiling::PrimitiveBatch) $2 = PrimitiveBatch {
key: AlphaBatchKey {
kind: TextRun,
flags: AlphaBatchKeyFlags {
bits: '\x03'
},
blend_mode: Subpixel(ColorF {
r: 0,
g: 0,
b: 0,
a: 1
}),
textures: BatchTextures {
colors: [TextureCache(CacheTextureId(0)), Invalid, Invalid]
}
},
instances: vec![PrimitiveInstance {
global_prim_id: 555,
prim_address: GpuStoreAddress(6523),
task_index: 0,
clip_task_index: 41,
layer_index: 15,
sub_index: 6524,
z_sort_index: 164,
user_data: [6012, 0]
}, PrimitiveInstance {
global_prim_id: 555,
prim_address: GpuStoreAddress(6523),
task_index: 0,
clip_task_index: 41,
layer_index: 15,
sub_index: 6525,
z_sort_index: 164,
user_data: [6013, 0]
}, PrimitiveInstance {
global_prim_id: 555,
prim_address: GpuStoreAddress(6523),
task_index: 0,
clip_task_index: 41,
layer_index: 15,
sub_index: 6526,
z_sort_index: 164,
user_data: [6014, 0]
}, PrimitiveInstance {
global_prim_id: 555,
prim_address: GpuStoreAddress(6523),
task_index: 0,
clip_task_index: 41,
layer_index: 15,
sub_index: 6527,
z_sort_index: 164,
user_data: [6015, 0]
}, PrimitiveInstance {
global_prim_id: 555,
prim_address: GpuStoreAddress(6523),
task_index: 0,
clip_task_index: 41,
layer_index: 15,
sub_index: 6528,
z_sort_index: 164,
user_data: [6016, 0]
}, PrimitiveInstance {
global_prim_id: 555,
prim_address: GpuStoreAddress(6523),
task_index: 0,
clip_task_index: 41,
layer_index: 15,
sub_index: 6529,
z_sort_index: 164,
user_data: [6017, 0]
}, PrimitiveInstance {
global_prim_id: 555,
prim_address: GpuStoreAddress(6523),
task_index: 0,
clip_task_index: 41,
layer_index: 15,
sub_index: 6530,
z_sort_index: 164,
user_data: [6018, 0]
}, PrimitiveInstance {
global_prim_id: 555,
prim_address: GpuStoreAddress(6523),
task_index: 0,
clip_task_index: 41,
layer_index: 15,
sub_index: 6531,
z_sort_index: 164,
user_data: [6019, 0]
}, PrimitiveInstance {
global_prim_id: 555,
prim_address: GpuStoreAddress(6523),
task_index: 0,
clip_task_index: 41,
layer_index: 15,
sub_index: 6532,
z_sort_index: 164,
user_data: [6020, 0]
}, PrimitiveInstance {
global_prim_id: 555,
prim_address: GpuStoreAddress(6523),
task_index: 0,
clip_task_index: 41,
layer_index: 15,
sub_index: 6533,
z_sort_index: 164,
user_data: [6021, 0]
}, PrimitiveInstance {
global_prim_id: 555,
prim_address: GpuStoreAddress(6523),
task_index: 0,
clip_task_index: 41,
layer_index: 15,
sub_index: 6534,
z_sort_index: 164,
user_data: [6022, 0]
}, PrimitiveInstance {
global_prim_id: 555,
prim_address: GpuStoreAddress(6523),
task_index: 0,
clip_task_index: 41,
layer_index: 15,
sub_index: 6535,
z_sort_index: 164,
user_data: [6023, 0]
}, PrimitiveInstance {
global_prim_id: 555,
prim_address: GpuStoreAddress(6523),
task_index: 0,
clip_task_index: 41,
layer_index: 15,
sub_index: 6536,
z_sort_index: 164,
user_data: [6024, 0]
}, PrimitiveInstance {
global_prim_id: 555,
prim_address: GpuStoreAddress(6523),
task_index: 0,
clip_task_index: 41,
layer_index: 15,
sub_index: 6537,
z_sort_index: 164,
user_data: [6025, 0]
}, PrimitiveInstance {
global_prim_id: 555,
prim_address: GpuStoreAddress(6523),
task_index: 0,
clip_task_index: 41,
layer_index: 15,
sub_index: 6538,
z_sort_index: 164,
user_data: [6026, 0]
}],
item_rects: vec![TypedRect<i32, webrender_traits::units::DevicePixel> {
origin: TypedPoint2D<i32, webrender_traits::units::DevicePixel> {
x: 1479,
y: 1426,
_unit: PhantomData<webrender_traits::units::DevicePixel> {

}
},
size: TypedSize2D<i32, webrender_traits::units::DevicePixel> {
width: 199,
height: 17,
_unit: PhantomData<webrender_traits::units::DevicePixel> {

}
}
}]
}

[glennw]

@jdm I'll fix this today - the assert is incorrect.

[glennw]

In the interim, until this lands in Servo - you should be able to prevent the assertion by running with an extra option - -Z disable-subpixel-aa