Bug 108935 - [LLVM Regression,bisected] Witcher 3 Corrupted Terrain
Summary: [LLVM Regression,bisected] Witcher 3 Corrupted Terrain
Status: NEW
Alias: None
Product: Mesa
Classification: Unclassified
Component: Drivers/Vulkan/radeon (show other bugs)
Version: git
Hardware: x86-64 (AMD64) Linux (All)
: medium normal
Assignee: mesa-dev
QA Contact: mesa-dev
URL:
Whiteboard:
Keywords:
Depends on:
Blocks:
 
Reported: 2018-12-03 21:34 UTC by oschowa
Modified: 2018-12-04 11:21 UTC (History)
1 user (show)

See Also:
i915 platform:
i915 features:


Attachments
screenshot (4.56 MB, image/png)
2018-12-03 21:34 UTC, oschowa
Details

Note You need to log in before you can comment on or make changes to this bug.
Description oschowa 2018-12-03 21:34:39 UTC
Created attachment 142706 [details]
screenshot

When running The Witcher 3 through DXVK there is terrain corruption in specific areas. This only occurs when radv is build against LLVM8-svn (r348050).
I tested the following configurations:

- Mesa 18.2.5 + LLVM 7 -> renders correctly
- Mesa-git b186731d5e413c + LLVM7 -> renders correctly
- Mesa-git b186731d5e413c + LLVM8 r348050 -> corrupted

My gpu is an RX580. I'll also attach a screenshot, savegame and renderdoc capture of the problematic area.

renderdoc capture: https://drive.google.com/open?id=1Rb2fsZoBLhp6h7RTiCLBJ5mcZwLl_2Ai

savegame: https://drive.google.com/open?id=1hKwP_fOX5rDZM4U24xwWWAnvHQHGHN9b
Comment 1 Samuel Pitoiset 2018-12-04 11:21:31 UTC
The problem can be reproduced on Polaris using the attached RenderDoc capture.

Bisected to:

41f457ff4f2e1571126d778f897efd274d1993ba is the first bad commit
commit 41f457ff4f2e1571126d778f897efd274d1993ba
Author: Nicolai Haehnle <nhaehnle@gmail.com>
Date:   Thu Nov 29 11:06:26 2018 +0000

    AMDGPU/InsertWaitcnts: Remove the dependence on MachineLoopInfo
    
    Summary:
    MachineLoopInfo cannot be relied on for correctness, because it cannot
    properly recognize loops in irreducible control flow which can be
    introduced by late machine basic block optimization passes. See the new
    test case for the reduced form of an example that occurred in practice.
    
    Use a simple fixpoint iteration instead.
    
    In order to facilitate this change, refactor WaitcntBrackets so that it
    only tracks pending events and registers, rather than also maintaining
    state that is relevant for the high-level algorithm. Various accessor
    methods can be removed or made private as a consequence.
    
    Affects (in radv):
    - dEQP-VK.glsl.loops.special.{for,while}_uniform_iterations.select_iteration_count_{fragment,vertex}
    
    Fixes: r345719 ("AMDGPU: Rewrite SILowerI1Copies to always stay on SALU")
    
    Reviewers: msearles, rampitec, scott.linder, kanarayan
    
    Subscribers: arsenm, kzhuravl, jvesely, wdng, yaxunl, dstuttard, tpr, t-tye, llvm-commits, hakzsam
    
    Differential Revision: https://reviews.llvm.org/D54231
    
    git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@347853 91177308-0d34-0410-b5e6-96231b3b80d8


Use of freedesktop.org services, including Bugzilla, is subject to our Code of Conduct. How we collect and use information is described in our Privacy Policy.