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

LLVM 3.3 Improves Its Loop Vectorizer

Compiler

Published on 15 February 2013 01:07 AM EST
Written by Michael Larabel in Compiler
2 Comments

The release of LLVM 3.3 is still months away, but one of its features already are notable improvements to its loop vectorizer.

Introduced in LLVM 3.2 was a loop vectorizer. From the earlier Phoronix article on the subject, "The LLVM Loop Vectorizer is the second vectorizer for the compiler infrastructure after its Basic Block Vectorizer for dealing with straight-line code. The Loop Vectorizer is meant to widen instructions in an original loop for operating on multiple consecutive loop iterations. As mentioned in the earlier Phoronix articles on the subject, this feature isn't enabled by default with the forthcoming LLVM 3.2 but can be flipped on via the -mllvm -vectorize-loops compiler switches." The functionality has also been described by LLVM developers.

I did run benchmarks of the LLVM Loop Vectorizer back in December and it could enhance the performance for some workloads. There's previously been talk of enabling the vectorizer by default in LLVM 3.3, but that hasn't happened yet.

What has happened in the code-base of LLVM 3.3 are a number of improvements to this loop vectorizer. With the latest development code, the LLVM 3.3 Loop Vectorizer now supports loops with an unknown trip count, run-time checks of pointers, reductions/inductions, if conversions, pointer induction variables, reverse iterators, vectorization of mixed types, vectorization of function calls, and partial unrolling during vectorization.

These LLVM 3.3 improvements should allow the loop vectorizer to be used more widely and applicable to more code-bases. Benchmarks of the LLVM Loop Vectorizer improvements are forthcoming as we begin to look at the LLVM/Clang 3.3 performance changes at Phoronix.

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. Rosewill RS-MI-01: An Ultra Low-Cost Mini-ITX Chassis
  2. D-Link DCS-2330L HD Wireless Network Camera
  3. Gigabyte AM1M-S2H
  4. AMD's New Athlon/Semprons Give Old Phenom CPUs A Big Run For The Money
Latest Linux Articles
  1. AMD Catalyst 14.4 Brings Few Linux Performance Improvements
  2. The Performance Of Fedora 20 Updated
  3. Clang Fights GCC On AMD's Athlon AM1 APU With Jaguar Cores
  4. Ubuntu 14.04 LTS vs. Oracle Linux vs. CentOS vs. openSUSE
Latest Linux News
  1. PC-BSD Is Developing Its Own Desktop Environment
  2. Valve Is Bringing VOGL To Windows & Working On Regression Tests
  3. Canonical Is Taking Over Linux 3.13 Kernel Maintenance
  4. Google Web Designer Is Now Natively Available On Linux
  5. Ubuntu 14.10 Is Codenamed The Utopic Unicorn
  6. Audacious 3.5 Lightweight Audio Player Released
  7. Steam Updated For Ubuntu 14.04 LTS, SteamOS
  8. DNF 0.5 Yum Replacement Now Supports Groups
  9. Red Hat Enterprise Linux 7.0 Is Looking Fantastic
  10. Intel Is Launching An Interesting Bay Trail NUC Next Week
  11. Another X.Org EVoC Proposed For OpenGL 4+ Tests
  12. The Best Features Coming With Qt 5.3
Latest Forum Discussions
  1. Linux Kernel Developers Fed Up With Ridiculous Bugs In Systemd
  2. The Most Amazing OpenGL Tech Demo In 64kb
  3. Announcing radeontop, a tool for viewing the GPU usage
  4. HTPC-upgrade advice: AMD Richland A8-7600 or Kaveri A10-6700T ???
  5. New card. Open source drivers only.
  6. The GNOME Foundation Is Running Short On Money
  7. Script for Fan Speed Control
  8. Torvalds Is Unconvinced By LTO'ing A Linux Kernel