Bug 1604625 - Add nightly config value to enable GL error checking. r…

…=kvark

Differential Revision: https://phabricator.services.mozilla.com/D57549

[wrupdater] From https://hg.mozilla.org/mozilla-central/rev/35af0b925215124a619bc054aeeb8d01e99b4e63

webrender/src/device/gl.rs

@@ -1253,6 +1253,7 @@ impl Device {
         allow_texture_swizzling: bool,
         dump_shader_source: Option<String>,
         surface_origin_is_top_left: bool,
+        panic_on_gl_error: bool,
     ) -> Device {
         let mut max_texture_size = [0];
         let mut max_texture_layers = [0];
@@ -1279,11 +1280,12 @@ impl Device {
         // this on release builds because the synchronous call can stall the
         // pipeline.
         let supports_khr_debug = supports_extension(&extensions, "GL_KHR_debug");
-        if cfg!(debug_assertions) {
+        if panic_on_gl_error || cfg!(debug_assertions) {
             gl = gl::ErrorReactingGl::wrap(gl, move |gl, name, code| {
                 if supports_khr_debug {
                     Self::log_driver_messages(gl);
                 }
+                println!("Caught GL error {:x} at {}", code, name);
                 panic!("Caught GL error {:x} at {}", code, name);
             });
         }

webrender/src/renderer.rs

@@ -1974,6 +1974,7 @@ impl Renderer {
             options.allow_texture_swizzling,
             options.dump_shader_source.take(),
             options.surface_origin_is_top_left,
+            options.panic_on_gl_error,
         );
 
         let color_cache_formats = device.preferred_color_formats();
@@ -6178,6 +6179,9 @@ pub struct RendererOptions {
     /// The configuration options defining how WR composites the final scene.
     pub compositor_config: CompositorConfig,
     pub enable_gpu_markers: bool,
+    /// If true, panic whenever a GL error occurs. This has a significant
+    /// performance impact, so only use when debugging specific problems!
+    pub panic_on_gl_error: bool,
 }
 
 impl Default for RendererOptions {
@@ -6233,6 +6237,7 @@ impl Default for RendererOptions {
             surface_origin_is_top_left: false,
             compositor_config: CompositorConfig::default(),
             enable_gpu_markers: true,
+            panic_on_gl_error: false,
         }
     }
 }