1. Computers
  2. Display Drivers
  3. Graphics Cards
  4. Memory
  5. Motherboards
  6. Processors
  7. Software
  8. Storage
  9. Operating Systems


Facebook RSS Twitter Twitter Google Plus


Phoronix Test Suite

OpenBenchmarking.org

Mesa "Flatland" GLSL IR Proposal

Mesa

Published on 07 February 2014 10:44 AM EST
Written by Michael Larabel in Mesa
1 Comment

A new GLSL intermediate representation (IR) approach has been proposed for Mesa in replacing its existing tree-based representation for shaders.

Connor Abbott, the high school student that started out doing low-level, technical work on the reverse-engineered Lima ARM Linux graphics driver has expanded his sights. The young but knowledgeable free software developer last month began working on SSA support for Mesa's GLSL IR and now may rework the GLSL intermediate representation entirely.

Ian Romanick at FOSDEM last week covered Mesa's existing tree-like shader IR spearheaded by the Intel developers in their open-source Linux graphics driver. The presentation slides can be found in PDF form. There's also a WebM video.

Ultimately this intermediate representation needs to be overhauled or replaced entirely, but the next step is what's still up in the air. Connor Abbott has now started a new developers' mailing list thread entitled Flatland.

Connor's proposal includes, "rather than slowly introducing changes across the board, we create the IR in its final form in the beginning, write passes to flatten and unflatten the IR, and then piece-by-piece rewrite the rest of the compiler. We're going to have to rewrite a lot of the passes to support SSA in the first place, so why not convert them to a flat IR while we're at it? The benefit of this is that it's much easier to do asynchronously and in parallel; rather than introducing changes to the entire thing at once, several people can convert this and that pass, the frontend, the linker, etc. independently. It would entail some extra overhead during the transition in the form of the flattening and unflattening passes, but I think it would be worth it for the immediate benefits (optimizations like GVN-GCM and CSE made possible, etc.)."

Pending sufficient interest in the "Flatland" IR approach he's willing to come up with the basic patches to implement his approach.

AMD's Alex Deucher has already come out and suggested just moving to LLVM directly. Using LLVM right now is the Radeon driver with their OpenCL/Compute support and as a shader compiler too while it's also used by the LLVMpipe driver. Nouveau has played with LLVM support too. At past FOSDEMs there's been talk of Intel's Linux GPU driver moving to LLVM but that has yet to materialize and is expected to be a slow and daunting process.

We'll see soon how other developers respond on the Mesa mailing list.

About The Author
Michael Larabel is the principal author of Phoronix.com and founded the web-site in 2004 with a focus on enriching the Linux hardware experience and being the largest web-site devoted to Linux hardware reviews, particularly for products relevant to Linux gamers and enthusiasts but also commonly reviewing servers/workstations and embedded Linux devices. Michael has written more than 10,000 articles covering the state of Linux hardware support, Linux performance, graphics hardware drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and OpenBenchmarking.org automated testing software. He can be followed via and or contacted via .
Latest Linux Hardware Reviews
  1. A Walkthrough Of The New 32 System Open-Source Linux Benchmarking Test Farm
  2. Habey MITX-6771: Mini-ITX Board With Quad-Core J1900 Bay Trail
  3. OCZ Vector 150 SSD On Linux
  4. Noctua i4 CPU Cooler: Great For Cooling High-End LGA-2011v3 CPUs
Latest Linux Articles
  1. 17-Way Linux Graphics Card Comparison With Civilization Beyond Earth
  2. AMD Kaveri: Open-Source Radeon Gallium3D vs. Catalyst 14.12 Omega Driver
  3. 12-Way AMD Catalyst 14.12 vs. NVIDIA 346 Series Linux GPU Comparison
  4. AMD Catalyst 14.12 Omega Driver Brings Mixed Results For Linux Users
Latest Linux News
  1. Fedora Doesn't Yet Enable F2FS File-System Support
  2. XZ 5.2 Adds New Multi-Threaded Options
  3. Intel 2.99.917 X.Org Driver Released, 3.0 Release Finally Near
  4. Server-Side XCB Is Being Discussed For The X.Org Server
  5. Adreno A4xx Rendering With Freedreno Takes Shape
  6. Linux 3.19-rc1 Kernel Released Ahead Of Schedule
  7. X.Org Server 1.16.3 Released To Fix Security Issues
  8. Linux 3.19 Merge Window Closes Ahead Of Schedule
  9. MIPS R6 Architecture Now Supported By GCC
  10. LowRISC To Feature Tagged Memory & Minion Cores
Latest Forum Discussions
  1. FPS capped on Linux (AMD fglrx drivers)
  2. Maker3D - create your 3D RPG
  3. Need some hand holding with upgrading xserver
  4. Speeding up systemd networking service
  5. Major Performance Breakthrough Discovered For Intel's Mesa Driver
  6. Looking for an nVidia GPU, but not sure how well they are supported.
  7. Are there an app using HSA ?
  8. The New SuperTuxKart Looks Better, But Can Cause GPU/Driver Problems