Bug 109581

Summary:	[BISECTED] Nothing is Rendered on Sascha Willem's "subpasses" demo
Product:	Mesa	Reporter:	LunarG <johnz>
Component:	Drivers/Vulkan/intel	Assignee:	Matt Turner <mattst88>
Status:	RESOLVED FIXED	QA Contact:	Intel 3D Bugs Mailing List <intel-3d-bugs>
Severity:	major
Priority:	medium	CC:	david, jason, karen
Version:	git
Hardware:	x86-64 (AMD64)
OS:	Linux (All)
Whiteboard:
i915 platform:		i915 features:
Bug Depends on:
Bug Blocks:	109535

Description LunarG 2019-02-07 20:40:26 UTC

--Mesa Version--
mesa-19.0.0-rc1 or mesa-19.0.0rc2

--Hardware--
Intel Skylake Processor

--Description--
Nothing gets rendered to the window when the "subpasses" demo is run. Window is black.

Steps to reproduce:
-Build Mesa 19.0.0-rc1
-Clone and Sascha Willem's demos (https://github.com/SaschaWillems/Vulkan)
-Try to run "subpasses" demo

Comment 1 Jason Ekstrand 2019-02-07 21:04:58 UTC

I've bisected this bug to the following commit:

commit 613ac3aaa295ad2a6271ee8315e16ee31456fa9d (HEAD, refs/bisect/bad)
Author: Matt Turner <mattst88@gmail.com>
Date:   Mon Dec 10 11:06:16 2018 -0800

    i965: Compile fp64 software routines and lower double-ops
    
    Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

Comment 2 Jason Ekstrand 2019-02-07 21:05:45 UTC

Looks like the "Window is black" is because it's compiling shaders forever.  Haven't dug into why yet.

Comment 3 Matt Turner 2019-02-07 22:20:35 UTC

So, there was a follow-on fix to this:

commit 32e266a9a5897bb2bb1560f142ac820e69fdae35
Author: Matt Turner <mattst88@gmail.com>
Date:   Thu Jan 10 15:14:35 2019 -0800

    i965: Compile fp64 funcs only if we do not have 64-bit hardware support
    
    Brown bag fix...

but we only call compile_fp64_funcs() in src/mesa/drivers/dri/i965/brw_program.c, so I don't think this can affect Vulkan.

Comment 4 Jason Ekstrand 2019-02-07 22:25:39 UTC

It's definitely infinite-looping in the 64-bit lowering loop even on master.

Comment 5 Kenneth Graunke 2019-02-07 23:20:52 UTC

Bisection is correct, I figured out what's going on here.  We should have patches shortly.

Comment 6 Kenneth Graunke 2019-02-17 07:39:12 UTC

Fixed:

commit 535251487ba56c4fd98465c4682881c2b9734242
Author: Kenneth Graunke <kenneth@whitecape.org>
Date:   Fri Feb 15 14:52:20 2019 -0800

    nir: Don't reassociate add/mul chains containing only constants

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