Adding "discard" after "break" in WebGL (ANGLE) shader causes wrong image to be rendered

[0152la]

[Shaders, screenshots, error log, reproduction steps, etc.] [ZIP]

Recipient:

Variant:

Similar to #6. Confirmed to appear when run with GetImageAngle and not to appear when run with get_image.

[0152la]

AMD Report Form ("n/a" means not filled):

Graphics Card Model:
Radeon R9 Fury X

Graphics Card Part Number:
n/a

AMD Radeon Software Driver Version:
AMD Radeon Software Crimson Edition 16.9.2

Driver History:
Do Not Know

Operating System:
Windows 10 64-bit

Type of Issue:
Other

Crossfire Configuration:
No

Using Mantle:
No

Other Games/Applications:
Google Chrome

Describe the Issue and Steps to replicate:
We use a custom written WebGL launcher and Chrome (self-contained HTML available for download at [1]; paste the shader code in the top box and hit "Execute"). When rendering the shader via WebGL, the incorrect image is being produced (variant.png), compared to the original, correct image (original.png). The difference between the two shaders is an added "discard" statement after a "break" statement. We observed that this does not occur when using normal OpenGL, but it does occur when using a custom-built ANGLE-based launcher (available for download at [2]).

More information and a list of all used files is available at [3].

[1] http://htmlpreview.github.io/?https://github.com/mc-imperial/shader-compiler-bugs/blob/master/utils/webgl/webgl_viewer.html
[2] https://github.com/paulthomson/GetImageAngle
[3] https://github.com/mc-imperial/shader-compiler-bugs/issues/29

CPU Details:
Intel(R) Xeon(R) CPU E5-1630 v3 @ 3.70GHz, 3701 Mhz, 4 Core(s), 8 Logical Processor(s)

Display Devices and Connections used:
Dell S2009W on HDMI

Motherboard or System Make & Model:
n/a

Motherboard BIOS version:
n/a

System Memory Type & Amount:
32GB

Power Supply Wattage:
n/a

[0152la]

Issue persists with Radeon version 17.6.2.

[afd]

Do we think this is an AMD issue or an ANGLE issue?