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Issue metadata

Status: Fixed
Owner:
Closed: Jun 2018
Cc:
Components:
EstimatedDays: ----
NextAction: ----
OS: Linux , Windows
Pri: 3
Type: Bug-Regression



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webgl atan(0, <negative>) returns 0 instead of PI

Reported by david.ma...@kitware.com, May 9 2018

Issue description

UserAgent: Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/65.0.3325.181 Safari/537.36

Steps to reproduce the problem:
1. Using xvfb and mesa, google-chrome http://glslsandbox.com/e#26563.2 
2. Alternately, google-chrome atan_problem.html
3. 

What is the expected behavior?
The colors shown for atan(0, <negative number>) represent PI, not 0.

What went wrong?
atan(0, <negative>) returns 0.

Did this work before? Yes 64.0.3282.140

Does this work in other browsers? Yes

Chrome version: 66.0.3359.139  Channel: stable
OS Version: Linux version 4.4.0-121-generic (buildd@lcy01-amd64-004) (gcc version 5.4.0 20160609 (Ubuntu 5.4.0-6ubuntu1~16.04.9) ) #145-Ubuntu SMP Fri Apr 13 13:47:23 UTC 2018
Flash Version: 

I see this problem in another application that uses webGL's atan function.  I don't see it on the desktop, but I do see it when run via xvfb with mesa in Ubuntu 16.04.

I get the same result locally and in travis-ci.org.

It works correctly in Chrome 64, but fails in Chrome 65 and 66.

Result of glxinfo:

name of display: :99
display: :99  screen: 0
direct rendering: Yes
server glx vendor string: SGI
server glx version string: 1.4
server glx extensions:
    GLX_ARB_create_context, GLX_ARB_create_context_profile,
    GLX_ARB_fbconfig_float, GLX_ARB_framebuffer_sRGB, GLX_ARB_multisample,
    GLX_EXT_create_context_es2_profile, GLX_EXT_create_context_es_profile,
    GLX_EXT_fbconfig_packed_float, GLX_EXT_framebuffer_sRGB,
    GLX_EXT_import_context, GLX_EXT_texture_from_pixmap, GLX_EXT_visual_info,
    GLX_EXT_visual_rating, GLX_MESA_copy_sub_buffer, GLX_OML_swap_method,
    GLX_SGIS_multisample, GLX_SGIX_fbconfig, GLX_SGIX_pbuffer,
    GLX_SGIX_visual_select_group, GLX_SGI_make_current_read
client glx vendor string: Mesa Project and SGI
client glx version string: 1.4
client glx extensions:
    GLX_ARB_create_context, GLX_ARB_create_context_profile,
    GLX_ARB_create_context_robustness, GLX_ARB_fbconfig_float,
    GLX_ARB_framebuffer_sRGB, GLX_ARB_get_proc_address, GLX_ARB_multisample,
    GLX_EXT_buffer_age, GLX_EXT_create_context_es2_profile,
    GLX_EXT_create_context_es_profile, GLX_EXT_fbconfig_packed_float,
    GLX_EXT_framebuffer_sRGB, GLX_EXT_import_context,
    GLX_EXT_texture_from_pixmap, GLX_EXT_visual_info, GLX_EXT_visual_rating,
    GLX_INTEL_swap_event, GLX_MESA_copy_sub_buffer,
    GLX_MESA_multithread_makecurrent, GLX_MESA_query_renderer,
    GLX_MESA_swap_control, GLX_OML_swap_method, GLX_OML_sync_control,
    GLX_SGIS_multisample, GLX_SGIX_fbconfig, GLX_SGIX_pbuffer,
    GLX_SGIX_visual_select_group, GLX_SGI_make_current_read,
    GLX_SGI_swap_control, GLX_SGI_video_sync
GLX version: 1.4
GLX extensions:
    GLX_ARB_create_context, GLX_ARB_create_context_profile,
    GLX_ARB_fbconfig_float, GLX_ARB_framebuffer_sRGB,
    GLX_ARB_get_proc_address, GLX_ARB_multisample,
    GLX_EXT_create_context_es2_profile, GLX_EXT_create_context_es_profile,
    GLX_EXT_fbconfig_packed_float, GLX_EXT_framebuffer_sRGB,
    GLX_EXT_import_context, GLX_EXT_texture_from_pixmap, GLX_EXT_visual_info,
    GLX_EXT_visual_rating, GLX_MESA_copy_sub_buffer,
    GLX_MESA_multithread_makecurrent, GLX_MESA_query_renderer,
    GLX_OML_swap_method, GLX_SGIS_multisample, GLX_SGIX_fbconfig,
    GLX_SGIX_pbuffer, GLX_SGIX_visual_select_group, GLX_SGI_make_current_read
Extended renderer info (GLX_MESA_query_renderer):
    Vendor: VMware, Inc. (0xffffffff)
    Device: llvmpipe (LLVM 5.0, 256 bits) (0xffffffff)
    Version: 17.2.8
    Accelerated: no
    Video memory: 32175MB
    Unified memory: no
    Preferred profile: core (0x1)
    Max core profile version: 3.3
    Max compat profile version: 3.0
    Max GLES1 profile version: 1.1
    Max GLES[23] profile version: 3.0
OpenGL vendor string: VMware, Inc.
OpenGL renderer string: llvmpipe (LLVM 5.0, 256 bits)
OpenGL core profile version string: 3.3 (Core Profile) Mesa 17.2.8
OpenGL core profile shading language version string: 3.30
OpenGL core profile context flags: (none)
OpenGL core profile profile mask: core profile
OpenGL core profile extensions:
    GL_AMD_conservative_depth, GL_AMD_draw_buffers_blend,
    GL_AMD_seamless_cubemap_per_texture, GL_AMD_shader_stencil_export,
    GL_AMD_shader_trinary_minmax, GL_AMD_vertex_shader_layer,
    GL_AMD_vertex_shader_viewport_index, GL_ANGLE_texture_compression_dxt3,
    GL_ANGLE_texture_compression_dxt5, GL_ARB_ES2_compatibility,
    GL_ARB_ES3_compatibility, GL_ARB_arrays_of_arrays, GL_ARB_base_instance,
    GL_ARB_blend_func_extended, GL_ARB_buffer_storage,
    GL_ARB_clear_buffer_object, GL_ARB_clear_texture, GL_ARB_clip_control,
    GL_ARB_compressed_texture_pixel_storage,
    GL_ARB_conditional_render_inverted, GL_ARB_conservative_depth,
    GL_ARB_copy_buffer, GL_ARB_copy_image, GL_ARB_cull_distance,
    GL_ARB_debug_output, GL_ARB_depth_buffer_float, GL_ARB_depth_clamp,
    GL_ARB_direct_state_access, GL_ARB_draw_buffers,
    GL_ARB_draw_buffers_blend, GL_ARB_draw_elements_base_vertex,
    GL_ARB_draw_indirect, GL_ARB_draw_instanced, GL_ARB_enhanced_layouts,
    GL_ARB_explicit_attrib_location, GL_ARB_explicit_uniform_location,
    GL_ARB_fragment_coord_conventions, GL_ARB_fragment_layer_viewport,
    GL_ARB_fragment_shader, GL_ARB_framebuffer_object,
    GL_ARB_framebuffer_sRGB, GL_ARB_get_program_binary,
    GL_ARB_get_texture_sub_image, GL_ARB_gpu_shader_fp64,
    GL_ARB_gpu_shader_int64, GL_ARB_half_float_pixel,
    GL_ARB_half_float_vertex, GL_ARB_instanced_arrays,
    GL_ARB_internalformat_query, GL_ARB_internalformat_query2,
    GL_ARB_invalidate_subdata, GL_ARB_map_buffer_alignment,
    GL_ARB_map_buffer_range, GL_ARB_multi_bind, GL_ARB_multi_draw_indirect,
    GL_ARB_occlusion_query2, GL_ARB_pixel_buffer_object, GL_ARB_point_sprite,
    GL_ARB_program_interface_query, GL_ARB_provoking_vertex,
    GL_ARB_robustness, GL_ARB_sampler_objects, GL_ARB_seamless_cube_map,
    GL_ARB_seamless_cubemap_per_texture, GL_ARB_separate_shader_objects,
    GL_ARB_shader_bit_encoding, GL_ARB_shader_objects,
    GL_ARB_shader_stencil_export, GL_ARB_shader_subroutine,
    GL_ARB_shader_texture_lod, GL_ARB_shading_language_420pack,
    GL_ARB_shading_language_packing, GL_ARB_stencil_texturing, GL_ARB_sync,
    GL_ARB_texture_buffer_object, GL_ARB_texture_buffer_object_rgb32,
    GL_ARB_texture_buffer_range, GL_ARB_texture_compression_rgtc,
    GL_ARB_texture_cube_map_array, GL_ARB_texture_float,
    GL_ARB_texture_gather, GL_ARB_texture_mirror_clamp_to_edge,
    GL_ARB_texture_multisample, GL_ARB_texture_non_power_of_two,
    GL_ARB_texture_query_levels, GL_ARB_texture_rectangle, GL_ARB_texture_rg,
    GL_ARB_texture_rgb10_a2ui, GL_ARB_texture_stencil8,
    GL_ARB_texture_storage, GL_ARB_texture_storage_multisample,
    GL_ARB_texture_swizzle, GL_ARB_texture_view, GL_ARB_timer_query,
    GL_ARB_transform_feedback2, GL_ARB_transform_feedback3,
    GL_ARB_transform_feedback_instanced, GL_ARB_uniform_buffer_object,
    GL_ARB_vertex_array_bgra, GL_ARB_vertex_array_object,
    GL_ARB_vertex_attrib_64bit, GL_ARB_vertex_attrib_binding,
    GL_ARB_vertex_shader, GL_ARB_vertex_type_10f_11f_11f_rev,
    GL_ARB_vertex_type_2_10_10_10_rev, GL_ARB_viewport_array,
    GL_ATI_blend_equation_separate, GL_ATI_texture_float,
    GL_ATI_texture_mirror_once, GL_EXT_abgr, GL_EXT_blend_equation_separate,
    GL_EXT_draw_buffers2, GL_EXT_draw_instanced, GL_EXT_framebuffer_blit,
    GL_EXT_framebuffer_multisample, GL_EXT_framebuffer_multisample_blit_scaled,
    GL_EXT_framebuffer_sRGB, GL_EXT_packed_depth_stencil, GL_EXT_packed_float,
    GL_EXT_pixel_buffer_object, GL_EXT_polygon_offset_clamp,
    GL_EXT_provoking_vertex, GL_EXT_shader_integer_mix, GL_EXT_texture_array,
    GL_EXT_texture_compression_dxt1, GL_EXT_texture_compression_rgtc,
    GL_EXT_texture_compression_s3tc, GL_EXT_texture_integer,
    GL_EXT_texture_mirror_clamp, GL_EXT_texture_sRGB,
    GL_EXT_texture_sRGB_decode, GL_EXT_texture_shared_exponent,
    GL_EXT_texture_snorm, GL_EXT_texture_swizzle, GL_EXT_timer_query,
    GL_EXT_transform_feedback, GL_EXT_vertex_array_bgra,
    GL_IBM_multimode_draw_arrays, GL_KHR_context_flush_control, GL_KHR_debug,
    GL_KHR_no_error, GL_MESA_pack_invert, GL_MESA_shader_integer_functions,
    GL_MESA_texture_signed_rgba, GL_MESA_ycbcr_texture,
    GL_NV_conditional_render, GL_NV_depth_clamp, GL_NV_packed_depth_stencil,
    GL_OES_EGL_image, GL_S3_s3tc

OpenGL version string: 3.0 Mesa 17.2.8
OpenGL shading language version string: 1.30
OpenGL context flags: (none)
OpenGL extensions:
    GL_AMD_conservative_depth, GL_AMD_draw_buffers_blend,
    GL_AMD_seamless_cubemap_per_texture, GL_AMD_shader_stencil_export,
    GL_AMD_shader_trinary_minmax, GL_ANGLE_texture_compression_dxt3,
    GL_ANGLE_texture_compression_dxt5, GL_APPLE_packed_pixels,
    GL_ARB_ES2_compatibility, GL_ARB_ES3_compatibility,
    GL_ARB_arrays_of_arrays, GL_ARB_base_instance, GL_ARB_blend_func_extended,
    GL_ARB_buffer_storage, GL_ARB_clear_buffer_object, GL_ARB_clear_texture,
    GL_ARB_clip_control, GL_ARB_color_buffer_float,
    GL_ARB_compressed_texture_pixel_storage,
    GL_ARB_conditional_render_inverted, GL_ARB_conservative_depth,
    GL_ARB_copy_buffer, GL_ARB_copy_image, GL_ARB_cull_distance,
    GL_ARB_debug_output, GL_ARB_depth_buffer_float, GL_ARB_depth_clamp,
    GL_ARB_depth_texture, GL_ARB_draw_buffers, GL_ARB_draw_buffers_blend,
    GL_ARB_draw_elements_base_vertex, GL_ARB_draw_instanced,
    GL_ARB_explicit_attrib_location, GL_ARB_explicit_uniform_location,
    GL_ARB_fragment_coord_conventions, GL_ARB_fragment_program,
    GL_ARB_fragment_program_shadow, GL_ARB_fragment_shader,
    GL_ARB_framebuffer_object, GL_ARB_framebuffer_sRGB,
    GL_ARB_get_program_binary, GL_ARB_get_texture_sub_image,
    GL_ARB_half_float_pixel, GL_ARB_half_float_vertex,
    GL_ARB_instanced_arrays, GL_ARB_internalformat_query,
    GL_ARB_internalformat_query2, GL_ARB_invalidate_subdata,
    GL_ARB_map_buffer_alignment, GL_ARB_map_buffer_range, GL_ARB_multi_bind,
    GL_ARB_multisample, GL_ARB_multitexture, GL_ARB_occlusion_query,
    GL_ARB_occlusion_query2, GL_ARB_pixel_buffer_object,
    GL_ARB_point_parameters, GL_ARB_point_sprite,
    GL_ARB_program_interface_query, GL_ARB_provoking_vertex,
    GL_ARB_robustness, GL_ARB_sampler_objects, GL_ARB_seamless_cube_map,
    GL_ARB_seamless_cubemap_per_texture, GL_ARB_separate_shader_objects,
    GL_ARB_shader_bit_encoding, GL_ARB_shader_objects,
    GL_ARB_shader_stencil_export, GL_ARB_shader_texture_lod,
    GL_ARB_shading_language_100, GL_ARB_shading_language_420pack,
    GL_ARB_shading_language_packing, GL_ARB_shadow, GL_ARB_stencil_texturing,
    GL_ARB_sync, GL_ARB_texture_border_clamp, GL_ARB_texture_compression,
    GL_ARB_texture_compression_rgtc, GL_ARB_texture_cube_map,
    GL_ARB_texture_cube_map_array, GL_ARB_texture_env_add,
    GL_ARB_texture_env_combine, GL_ARB_texture_env_crossbar,
    GL_ARB_texture_env_dot3, GL_ARB_texture_float, GL_ARB_texture_gather,
    GL_ARB_texture_mirror_clamp_to_edge, GL_ARB_texture_mirrored_repeat,
    GL_ARB_texture_multisample, GL_ARB_texture_non_power_of_two,
    GL_ARB_texture_query_levels, GL_ARB_texture_rectangle, GL_ARB_texture_rg,
    GL_ARB_texture_rgb10_a2ui, GL_ARB_texture_stencil8,
    GL_ARB_texture_storage, GL_ARB_texture_storage_multisample,
    GL_ARB_texture_swizzle, GL_ARB_texture_view, GL_ARB_timer_query,
    GL_ARB_transform_feedback2, GL_ARB_transform_feedback3,
    GL_ARB_transform_feedback_instanced, GL_ARB_transpose_matrix,
    GL_ARB_uniform_buffer_object, GL_ARB_vertex_array_bgra,
    GL_ARB_vertex_array_object, GL_ARB_vertex_attrib_binding,
    GL_ARB_vertex_buffer_object, GL_ARB_vertex_program, GL_ARB_vertex_shader,
    GL_ARB_vertex_type_10f_11f_11f_rev, GL_ARB_vertex_type_2_10_10_10_rev,
    GL_ARB_window_pos, GL_ATI_blend_equation_separate, GL_ATI_draw_buffers,
    GL_ATI_fragment_shader, GL_ATI_separate_stencil,
    GL_ATI_texture_compression_3dc, GL_ATI_texture_env_combine3,
    GL_ATI_texture_float, GL_ATI_texture_mirror_once, GL_EXT_abgr,
    GL_EXT_bgra, GL_EXT_blend_color, GL_EXT_blend_equation_separate,
    GL_EXT_blend_func_separate, GL_EXT_blend_minmax, GL_EXT_blend_subtract,
    GL_EXT_compiled_vertex_array, GL_EXT_copy_texture, GL_EXT_draw_buffers2,
    GL_EXT_draw_instanced, GL_EXT_draw_range_elements, GL_EXT_fog_coord,
    GL_EXT_framebuffer_blit, GL_EXT_framebuffer_multisample,
    GL_EXT_framebuffer_multisample_blit_scaled, GL_EXT_framebuffer_object,
    GL_EXT_framebuffer_sRGB, GL_EXT_gpu_program_parameters,
    GL_EXT_multi_draw_arrays, GL_EXT_packed_depth_stencil,
    GL_EXT_packed_float, GL_EXT_packed_pixels, GL_EXT_pixel_buffer_object,
    GL_EXT_point_parameters, GL_EXT_polygon_offset,
    GL_EXT_polygon_offset_clamp, GL_EXT_provoking_vertex,
    GL_EXT_rescale_normal, GL_EXT_secondary_color,
    GL_EXT_separate_specular_color, GL_EXT_shader_integer_mix,
    GL_EXT_shadow_funcs, GL_EXT_stencil_two_side, GL_EXT_stencil_wrap,
    GL_EXT_subtexture, GL_EXT_texture, GL_EXT_texture3D,
    GL_EXT_texture_array, GL_EXT_texture_compression_dxt1,
    GL_EXT_texture_compression_latc, GL_EXT_texture_compression_rgtc,
    GL_EXT_texture_compression_s3tc, GL_EXT_texture_cube_map,
    GL_EXT_texture_edge_clamp, GL_EXT_texture_env_add,
    GL_EXT_texture_env_combine, GL_EXT_texture_env_dot3,
    GL_EXT_texture_integer, GL_EXT_texture_lod_bias,
    GL_EXT_texture_mirror_clamp, GL_EXT_texture_object,
    GL_EXT_texture_rectangle, GL_EXT_texture_sRGB, GL_EXT_texture_sRGB_decode,
    GL_EXT_texture_shared_exponent, GL_EXT_texture_snorm,
    GL_EXT_texture_swizzle, GL_EXT_timer_query, GL_EXT_transform_feedback,
    GL_EXT_vertex_array, GL_EXT_vertex_array_bgra,
    GL_IBM_multimode_draw_arrays, GL_IBM_rasterpos_clip,
    GL_IBM_texture_mirrored_repeat, GL_INGR_blend_func_separate,
    GL_KHR_context_flush_control, GL_KHR_debug, GL_KHR_no_error,
    GL_MESA_pack_invert, GL_MESA_shader_integer_functions,
    GL_MESA_texture_signed_rgba, GL_MESA_window_pos, GL_MESA_ycbcr_texture,
    GL_NV_blend_square, GL_NV_conditional_render, GL_NV_depth_clamp,
    GL_NV_fog_distance, GL_NV_light_max_exponent, GL_NV_packed_depth_stencil,
    GL_NV_primitive_restart, GL_NV_texgen_reflection,
    GL_NV_texture_env_combine4, GL_NV_texture_rectangle, GL_OES_EGL_image,
    GL_OES_read_format, GL_S3_s3tc, GL_SGIS_generate_mipmap,
    GL_SGIS_texture_border_clamp, GL_SGIS_texture_edge_clamp,
    GL_SGIS_texture_lod, GL_SUN_multi_draw_arrays

OpenGL ES profile version string: OpenGL ES 3.0 Mesa 17.2.8
OpenGL ES profile shading language version string: OpenGL ES GLSL ES 3.00
OpenGL ES profile extensions:
    GL_ANGLE_texture_compression_dxt3, GL_ANGLE_texture_compression_dxt5,
    GL_APPLE_texture_max_level, GL_EXT_base_instance,
    GL_EXT_blend_func_extended, GL_EXT_blend_minmax,
    GL_EXT_clip_cull_distance, GL_EXT_color_buffer_float,
    GL_EXT_compressed_ETC1_RGB8_sub_texture, GL_EXT_copy_image,
    GL_EXT_discard_framebuffer, GL_EXT_draw_buffers,
    GL_EXT_draw_buffers_indexed, GL_EXT_draw_elements_base_vertex,
    GL_EXT_frag_depth, GL_EXT_map_buffer_range, GL_EXT_multi_draw_arrays,
    GL_EXT_polygon_offset_clamp, GL_EXT_read_format_bgra,
    GL_EXT_separate_shader_objects, GL_EXT_shader_integer_mix,
    GL_EXT_texture_border_clamp, GL_EXT_texture_compression_dxt1,
    GL_EXT_texture_format_BGRA8888, GL_EXT_texture_rg,
    GL_EXT_texture_sRGB_decode, GL_EXT_texture_type_2_10_10_10_REV,
    GL_EXT_unpack_subimage, GL_KHR_context_flush_control, GL_KHR_debug,
    GL_KHR_no_error, GL_MESA_shader_integer_functions, GL_NV_draw_buffers,
    GL_NV_fbo_color_attachments, GL_NV_read_buffer, GL_NV_read_depth,
    GL_NV_read_depth_stencil, GL_NV_read_stencil, GL_OES_EGL_image,
    GL_OES_EGL_image_external, GL_OES_EGL_sync,
    GL_OES_compressed_ETC1_RGB8_texture, GL_OES_copy_image, GL_OES_depth24,
    GL_OES_depth_texture, GL_OES_depth_texture_cube_map,
    GL_OES_draw_buffers_indexed, GL_OES_draw_elements_base_vertex,
    GL_OES_element_index_uint, GL_OES_fbo_render_mipmap,
    GL_OES_get_program_binary, GL_OES_mapbuffer, GL_OES_packed_depth_stencil,
    GL_OES_rgb8_rgba8, GL_OES_standard_derivatives, GL_OES_stencil8,
    GL_OES_surfaceless_context, GL_OES_texture_3D,
    GL_OES_texture_border_clamp, GL_OES_texture_float,
    GL_OES_texture_float_linear, GL_OES_texture_half_float,
    GL_OES_texture_half_float_linear, GL_OES_texture_npot,
    GL_OES_texture_stencil8, GL_OES_vertex_array_object,
    GL_OES_vertex_half_float
 
atan_problem.html
3.0 KB View Download
Cc: oetu...@nvidia.com
Components: Internals>GPU>ANGLE
Does this affect other platforms?
Components: -Internals>GPU>ANGLE
Oh, it seems your Renderer is LLVM pipe for some reason.
On travis-ci.org, the OpenGL version is different and still shows the issue:

glxinfo:

server glx vendor string: SGI
server glx version string: 1.4
server glx extensions:
  ...
client glx vendor string: Mesa Project and SGI
client glx version string: 1.4
client glx extensions:
  ...
GLX version: 1.4
GLX extensions:
   ...
OpenGL vendor string: VMware, Inc.
OpenGL renderer string: Gallium 0.4 on llvmpipe (LLVM 3.4, 256 bits)
OpenGL version string: 2.1 Mesa 10.1.3
OpenGL shading language version string: 1.30
...
That's still LLVM pipe, which is a software implementation of OpenGL.
Yes.  Though I find it odd that Chrome 64 works and Chrome 65 and 66 don't without changing the OpenGL version.

Comment 6 by kbr@chromium.org, May 9 2018

Components: Internals>GPU>SwiftShader
Please provide the text contents of the about:gpu page. I suspect this is caused by the integration of SwiftShader as Chrome's rendering fallback in M65, and think that llvmpipe is probably blacklisted, causing the SwiftShader fallback.

Labels: Needs-Bisect Needs-Triage-M66

Comment 8 by kbr@chromium.org, May 10 2018

Labels: -Pri-2 Pri-3
Without more information about the urgency of this bug I'm downgrading it. The P2 bucket is too big right now.

Labels: Triaged-ET Needs-Feedback
Tested the issue on chrome reported version 66.0.3359.139 using Ubuntu 14.04 with steps mentioned below:
1) Launched chrome reported version through terminal using: google-chrome http://glslsandbox.com/e#26563.2
2) Opened Devtools > Console to check the excepted behaviour/what went wrong provided in comment# 0, didn't observed anything related to it
3) Also launched chrome for: google-chrome atan_problem.html, didn't observed anything as mentioned in step-2
Observations: Also tested the issue on chrome version# 64.0.3282.140(as provided in comment#0), seen same behaviour as mentioned above

@Reporter: Please find the attached screencast for your reference and let us know if we missed anything in reproducing the issue, if possible could you please provide the scrrencast of the issue which helps us in better understanding, any further inputs on this issue are most helpful. Find attached for GPU details.

Thanks!
841296.ogv
7.6 MB View Download
841296 - GPU.pdf
105 KB Download
This problem occurs when I run chrome via XVFB (both locally an in travis-ci's environment).  For instance, if I run
xvfb-run -s "-ac -screen 0 1280x1024x24" google-chrome http://glslsandbox.com/e#26563.2
and then look at the XVFB screen buffer, I get the attached screenshot (note the center left is red not cyan indicating that atan is getting the wrong value).
screenshot.png
267 KB View Download
Project Member

Comment 11 by sheriffbot@chromium.org, May 10 2018

Cc: viswa.karala@chromium.org
Labels: -Needs-Feedback
Thank you for providing more feedback. Adding the requester to the cc list.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot
I'm not certain how to get to the chrome://gpu information in Xvfb -- When using Xvfb, only interact with the browser programmatically or via a remote debugging session, and it prohibits navigating to chrome://gpu (or about:gpu).  Please advise.
I also have reproduced the problem on a Windows machine when starting chrome with the --disable-gpu flag.  It's about:gpu shows:


Graphics Feature Status
Canvas: Software only, hardware acceleration unavailable
CheckerImaging: Disabled
Flash: Software only. Hardware acceleration disabled
Flash Stage3D: Software only. Hardware acceleration disabled
Flash Stage3D Baseline profile: Software only. Hardware acceleration disabled
Compositing: Software only. Hardware acceleration disabled
Multiple Raster Threads: Enabled
Native GpuMemoryBuffers: Software only. Hardware acceleration disabled
Rasterization: Software only. Hardware acceleration disabled
Surface Synchronization: Enabled
Video Decode: Software only. Hardware acceleration disabled
WebGL: Software only, hardware acceleration unavailable
WebGL2: Software only, hardware acceleration unavailable
Problems Detected
Native GpuMemoryBuffers have been disabled, either via about:flags or command line.
Disabled Features: native_gpu_memory_buffers
Checker-imaging has been disabled via finch trial or the command line.
Disabled Features: checker_imaging
Version Information
Data exported	2018-05-10T13:05:00.598Z
Chrome version	Chrome/66.0.3359.139
Operating system	Windows NT 6.1.7601 SP1
Software rendering list URL	https://chromium.googlesource.com/chromium/src/+/a020eddf0d85fe84d4a6787b304f50aafb670969/gpu/config/software_rendering_list.json
Driver bug list URL	https://chromium.googlesource.com/chromium/src/+/a020eddf0d85fe84d4a6787b304f50aafb670969/gpu/config/gpu_driver_bug_list.json
ANGLE commit id	22c768fbda54
2D graphics backend	Skia/66 773868fdade5f9f0e7697e6d09c9bd80aaa9b402-
Command Line	"C:\Program Files (x86)\Google\Chrome\Application\chrome.exe" --disable-gpu --flag-switches-begin --autoplay-policy=document-user-activation-required --no-pings --top-chrome-md=material --enable-features=UseGoogleLocalNtp --disable-features=DoodlesOnLocalNtp,OneGoogleBarOnLocalNtp --flag-switches-end http://glslsandbox.com/e#26563.2
Driver Information
Initialization time	54
In-process GPU	false
Passthrough Command Decoder	false
Direct Composition	false
Supports overlays	false
Sandboxed	true
GPU0	VENDOR = 0x1002, DEVICE= 0x6809 *ACTIVE*
Optimus	false
Optimus	false
AMD switchable	false
Desktop compositing	Aero Glass
Diagonal Monitor Size of \\.\DISPLAY1	24.0"
Driver vendor	Advanced Micro Devices, Inc.
Driver version	13.251.1.0
Driver date	12-23-2013
Pixel shader version	1.00
Vertex shader version	1.00
Max. MSAA samples	4
Machine model name	
Machine model version	
GL_VENDOR	Google Inc.
GL_RENDERER	Google SwiftShader
GL_VERSION	OpenGL ES 2.0 SwiftShader 4.0.0.3
GL_EXTENSIONS	GL_OES_compressed_ETC1_RGB8_texture GL_OES_depth24 GL_OES_depth32 GL_OES_depth_texture GL_OES_depth_texture_cube_map GL_OES_EGL_image GL_OES_EGL_image_external GL_OES_EGL_sync GL_OES_element_index_uint GL_OES_framebuffer_object GL_OES_packed_depth_stencil GL_OES_rgb8_rgba8 GL_OES_standard_derivatives GL_OES_surfaceless_context GL_OES_texture_float GL_OES_texture_float_linear GL_OES_texture_half_float GL_OES_texture_half_float_linear GL_OES_texture_npot GL_OES_texture_3D GL_OES_vertex_half_float GL_EXT_blend_minmax GL_EXT_color_buffer_half_float GL_EXT_draw_buffers GL_EXT_instanced_arrays GL_EXT_occlusion_query_boolean GL_EXT_read_format_bgra GL_EXT_texture_compression_dxt1 GL_EXT_texture_filter_anisotropic GL_EXT_texture_format_BGRA8888 GL_EXT_texture_rg GL_ARB_texture_rectangle GL_ANGLE_framebuffer_blit GL_ANGLE_framebuffer_multisample GL_ANGLE_instanced_arrays GL_ANGLE_texture_compression_dxt3 GL_ANGLE_texture_compression_dxt5 GL_APPLE_texture_format_BGRA8888 GL_CHROMIUM_color_buffer_float_rgba GL_CHROMIUM_texture_filtering_hint GL_NV_fence GL_NV_framebuffer_blit GL_NV_read_depth GL_EXT_color_buffer_float
Disabled Extensions	
Disabled WebGL Extensions	
Window system binding vendor	Google Inc.
Window system binding version	1.4 SwiftShader 4.0.0.3
Window system binding extensions	EGL_KHR_create_context EGL_KHR_get_all_proc_addresses EGL_KHR_gl_texture_2D_image EGL_KHR_gl_texture_cubemap_image EGL_KHR_gl_renderbuffer_image EGL_KHR_fence_sync EGL_KHR_image_base EGL_KHR_surfaceless_context EGL_ANDROID_framebuffer_target EGL_ANDROID_recordable
Direct rendering	Yes
Reset notification strategy	0x0000
GPU process crash count	0
Compositor Information
Tile Update Mode	One-copy
Partial Raster	Enabled
GpuMemoryBuffers Status
ATC	Software only
ATCIA	Software only
DXT1	Software only
DXT5	Software only
ETC1	Software only
R_8	Software only
R_16	Software only
RG_88	Software only
BGR_565	Software only
RGBA_4444	Software only
RGBX_8888	GPU_READ, SCANOUT
RGBA_8888	GPU_READ, SCANOUT
BGRX_8888	Software only
BGRX_1010102	Software only
RGBX_1010102	Software only
BGRA_8888	Software only
RGBA_F16	Software only
YVU_420	Software only
YUV_420_BIPLANAR	Software only
UYVY_422	Software only
Display(s) Information
Info	Display[2528732444] bounds=0,0 1920x1200, workarea=0,0 1920x1170, scale=1, external
Color space information	{primaries:[[0.4851,0.3488,0.1302,],[0.2502,0.6977,0.0521,],[0.0227,0.1163,0.6859,],], transfer:0.0774*x + 0.0000 if x < 0.0404 else (0.9479*x + 0.0521)**2.4000 + 0.0000, matrix:RGB, range:FULL}
Bits per color component	8
Bits per pixel	24
Video Acceleration Information
Diagnostics
0
b3DAccelerationEnabled	true
b3DAccelerationExists	true
bAGPEnabled	true
bAGPExistenceValid	true
bAGPExists	true
bCanRenderWindow	true
bDDAccelerationEnabled	true
bDriverBeta	false
bDriverDebug	false
bDriverSigned	false
bDriverSignedValid	false
bNoHardware	false
dwBpp	32
dwDDIVersion	11
dwHeight	1200
dwRefreshRate	60
dwWHQLLevel	0
dwWidth	1920
iAdapter	0
lDriverSize	1319064
lMiniVddSize	0
szAGPStatusEnglish	Enabled
szAGPStatusLocalized	Enabled
szChipType	ATI FirePro V(FireGL V) Graphics Adapter SDI (0x6809)
szD3DStatusEnglish	Enabled
szD3DStatusLocalized	Enabled
szDACType	Internal DAC(400MHz)
szDDIVersionEnglish	11
szDDIVersionLocalized	11
szDDStatusEnglish	Enabled
szDDStatusLocalized	Enabled
szDXVAHDEnglish	Not Supported
szDXVAModes	ModeMPEG2_A ModeMPEG2_C ModeVC1_C ModeWMV9_C
szDescription	AMD FirePro W5000 (FireGL V) Graphics Adapter
szDeviceId	0x6809
szDeviceIdentifier	{D7B71EE2-2B49-11CF-4777-0C2BBEC2C535}
szDeviceName	\\.\DISPLAY1
szDisplayMemoryEnglish	1674 MB
szDisplayMemoryLocalized	1674 MB
szDisplayModeEnglish	1920 x 1200 (32 bit) (60Hz)
szDisplayModeLocalized	1920 x 1200 (32 bit) (60Hz)
szDriverAssemblyVersion	13.251.1.0
szDriverAttributes	Final Retail
szDriverDateEnglish	12/24/2013 05:37:28
szDriverDateLocalized	12/24/2013 5:37:28
szDriverLanguageEnglish	English
szDriverLanguageLocalized	English
szDriverModelEnglish	WDDM 1.1
szDriverModelLocalized	WDDM 1.1
szDriverName	aticfx64.dll,aticfx64.dll,aticfx64.dll,aticfx32,aticfx32,aticfx32,atiumd64.dll,atidxx64.dll,atidxx64.dll,atiumdag,atidxx32,atidxx32,atiumdva,atiumd6a.cap,atitmm64.dll
szDriverNodeStrongName	oem128.inf:ATI.Mfg.NTamd64.6.1:ati2mtag_R575BGL:13.251.1.0:pci\ven_1002&dev_6809&subsys_0b061028
szDriverSignDate	
szDriverVersion	8.17.0010.1247
szKeyDeviceID	Enum\PCI\VEN_1002&DEV_6809&SUBSYS_0B061028&REV_00
szKeyDeviceKey	\Registry\Machine\System\CurrentControlSet\Control\Video\{7FCB58BE-A574-4857-8E77-975DCE7F761A}\0000
szManufacturer	Advanced Micro Devices, Inc.
szMiniVdd	n/a
szMiniVddDateEnglish	n/a
szMiniVddDateLocalized	n/a
szMonitorMaxRes	
szMonitorName	Dell U2412M(Digital)
szNotesEnglish	No problems found.
szNotesLocalized	No problems found.
szOverlayEnglish	Not Supported
szRankOfInstalledDriver	00E60001
szRegHelpText	
szRevision	
szRevisionId	0x0000
szSubSysId	0x0B061028
szTestResultD3D7English	Not run
szTestResultD3D7Localized	Not run
szTestResultD3D8English	Not run
szTestResultD3D8Localized	Not run
szTestResultD3D9English	Not run
szTestResultD3D9Localized	Not run
szTestResultDDEnglish	Not run
szTestResultDDLocalized	Not run
szVdd	n/a
szVendorId	0x1002
Log Messages
GpuProcessHostUIShim: The GPU process exited normally. Everything is okay.
Looking at the swiftshader code, I suspect that this bug was introduced here: https://swiftshader-review.googlesource.com/c/SwiftShader/+/13568.  I don't yet fully understand what is going on in the code, but the change here https://github.com/google/swiftshader/blob/master/src/Shader/ShaderCore.cpp#L406 looks suspect to me.

Comment 15 by kbr@chromium.org, May 10 2018

Labels: OS-Windows
Owner: sugoi@chromium.org
Status: Assigned (was: Unconfirmed)
It's possible to connect via vnc to a running xvfb instance. If it's running on the Travis CI this will probably be more complicated, but here are some instructions on how to do it: (found by searching for "xvfb view output":
https://stackoverflow.com/questions/12050021/how-to-make-xvfb-display-visible

Regardless, since you confirmed the bug on Windows, it's not necessary to reconfirm on Linux.

Alexis, can you triage this? The submitter might have identified the problematic area.

Labels: -Needs-Bisect RegressedIn-65 M-66 FoundIn-66 Target-66 hasbisect
Able to reproduce the issue on chrome reported version 66.0.3359.139 and latest stable# 66.0.3359.170 and same issue is not seen on 67.0.3396.40 and latest chrome# 68.0.3426.0 using Windows 10 HP ELITEBOOK Intel core i5 7th Generation laptop, hence providing reverse bisect info
Note: Unable to reproduce the issue on Linux and Mac

Reverse Bisect Info:
=====================
Last Bad build: 67.0.3364.0
First Good build: 67.0.3365.0
Note: Ran chromium bisect twice, for the first got all good builds, after increasing good build range got CL as follows

You are probably looking for a change made after 541486 (known good), but no later than 541500 (first known bad).
https://chromium.googlesource.com/chromium/src/+log/507a11acd6cae68872a027576aff193ebb198f90..989dbd8fc3af087ef525b437d498ee7941cbc6a3
Hence removing Needs-Bisect label, feel free to add it back if required.

Note: Unable to find the correct suspect from above changelog.

Thanks!
Thanks for reminding me of vnc.

I still see the problem in "Google Chrome 67.0.3396.40 beta" on Ubuntu via xvfb.  The about:gpu reports


Graphics Feature Status
Canvas: Software only, hardware acceleration unavailable
CheckerImaging: Disabled
Flash: Software only. Hardware acceleration disabled
Flash Stage3D: Software only. Hardware acceleration disabled
Flash Stage3D Baseline profile: Software only. Hardware acceleration disabled
Compositing: Software only. Hardware acceleration disabled
Multiple Raster Threads: Enabled
Native GpuMemoryBuffers: Software only. Hardware acceleration disabled
Rasterization: Software only. Hardware acceleration disabled
Surface Synchronization: Enabled
Video Decode: Software only. Hardware acceleration disabled
Viz Service Display Compositor: Disabled
WebGL: Software only, hardware acceleration unavailable
WebGL2: Software only, hardware acceleration unavailable
Problems Detected
Native GpuMemoryBuffers have been disabled, either via about:flags or command line.
Disabled Features: native_gpu_memory_buffers
Viz service display compositor is not enabled by default.
Disabled Features: viz_display_compositor
Checker-imaging has been disabled via finch trial or the command line.
Disabled Features: checker_imaging
Version Information
Data exported	2018-05-11T13:17:07.523Z
Chrome version	Chrome/67.0.3396.40
Operating system	Linux 4.4.0-124-generic
Software rendering list URL	https://chromium.googlesource.com/chromium/src/+/4d4e946fc6b643fe97197ead24e3a6f414385ad3/gpu/config/software_rendering_list.json
Driver bug list URL	https://chromium.googlesource.com/chromium/src/+/4d4e946fc6b643fe97197ead24e3a6f414385ad3/gpu/config/gpu_driver_bug_list.json
ANGLE commit id	f7d4f25ecb44
2D graphics backend	Skia/67 c097162d82fe7b13b349ed33bc17f1d2bafa7e82-
Command Line	/usr/bin/google-chrome-beta --incognito --flag-switches-begin --flag-switches-end http://glslsandbox.com/e#26563.2
Driver Information
Initialization time	15
In-process GPU	false
Passthrough Command Decoder	false
Direct Composition	false
Supports overlays	false
Sandboxed	true
GPU0	VENDOR = 0x80ee, DEVICE= 0xbeef
Optimus	false
AMD switchable	false
Driver vendor	
Driver version	
Driver date	
Pixel shader version	
Vertex shader version	
Max. MSAA samples	
Machine model name	
Machine model version	
GL_VENDOR	Google Inc. ()
GL_RENDERER	Google SwiftShader ()
GL_VERSION	OpenGL ES 2.0 SwiftShader ()
GL_EXTENSIONS	
Disabled Extensions	
Disabled WebGL Extensions	
Window system binding vendor	
Window system binding version	
Window system binding extensions	
Window manager	Unknown
Compositing manager	No
Direct rendering	Yes
Reset notification strategy	0x0000
GPU process crash count	0
System visual ID	0
RGBA visual ID	0
Compositor Information
Tile Update Mode	One-copy
Partial Raster	Enabled
GpuMemoryBuffers Status
ATC	Software only
ATCIA	Software only
DXT1	Software only
DXT5	Software only
ETC1	Software only
R_8	Software only
R_16	Software only
RG_88	Software only
BGR_565	Software only
RGBA_4444	Software only
RGBX_8888	Software only
RGBA_8888	Software only
BGRX_8888	Software only
BGRX_1010102	Software only
RGBX_1010102	Software only
BGRA_8888	Software only
RGBA_F16	Software only
YVU_420	Software only
YUV_420_BIPLANAR	Software only
UYVY_422	Software only
Display(s) Information
Info	Display[0] bounds=[0,0 1280x1024], workarea=[0,0 1280x1024], scale=1, external.
Color space information	{primaries:INVALID, transfer:INVALID, matrix:INVALID, range:INVALID}
Bits per color component	8
Bits per pixel	24
Video Acceleration Information

Comment 18 by sugoi@chromium.org, May 11 2018

I'm on it. I'll investigate this early next week.

Comment 19 by sugoi@chromium.org, May 11 2018

Cc: -oetu...@nvidia.com capn@chromium.org
Project Member

Comment 20 by bugdroid1@chromium.org, May 17 2018

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/b5adacad379e144581021e8fcccd243a5194e455

commit b5adacad379e144581021e8fcccd243a5194e455
Author: Alexis Hetu <sugoi@google.com>
Date: Thu May 17 01:33:32 2018

Roll SwiftShader 2a0def7..c8403ec

https://swiftshader.googlesource.com/SwiftShader.git/+log/2a0def7..c8403ec

BUG= chromium:841296 

TBR=kbr@chromium.org

TEST=bots

CQ_INCLUDE_TRYBOTS=luci.chromium.try:win_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_chromium_cfi_rel_ng;luci.chromium.try:android_optional_gpu_tests_rel

Change-Id: I3e6d72c823a849eca2b4f46cd28599c4d585a174
Reviewed-on: https://chromium-review.googlesource.com/1062287
Commit-Queue: Alexis Hétu <sugoi@chromium.org>
Reviewed-by: Alexis Hétu <sugoi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#559387}
[modify] https://crrev.com/b5adacad379e144581021e8fcccd243a5194e455/DEPS

Status: Fixed (was: Assigned)
This should be fixed now.

Comment 22 by capn@chromium.org, Jun 5 2018

This issue was fixed by https://swiftshader-review.googlesource.com/18868, but now we actually get QualityWarning results in dEQP, which needs investigation: https://issuetracker.google.com/issues/109745730
Labels: TE-Verified-M67 TE-Verified-67.0.3396.99
Able to reproduce the issue on chrome version 66.0.3359.139
Verified the fix on Windows-10 using Chrome version #67.0.3396.99 as per the comment #0 & 10
Attaching screenshot for reference.
Observed "colours shown for atan(0, <negative number>) represent PI".
Hence, the fix is working as expected. 
Adding the verified labels.
As per comment# 16, was unable to reproduce the issue on Linux, hence providing TE-Verified labels for Windows.

Thanks...!!
841296 - 67.0.3396.99.png
486 KB View Download

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