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 Benchmarking Platform
Phoromatic Test Orchestration

Benchmarking LLVM & Clang Against GCC 4.5

Michael Larabel

Published on 21 April 2010
Written by Michael Larabel
Page 6 of 6 - 17 Comments

LLVM-GCC had the best results with Himeno, a Poisson pressure solver, but when Clang was involved, it had the worst numbers. The LLVM-GCC binary produced 60% more MFLOPS than the LLVM Clang version.

Clang had not worked with John The Ripper, but with LLVM-GCC its performance was dismal compared to GCC 4.5.0. The 23-year-old compiler was 60% faster than LLVM-GCC.

Binaries from LLVM-GCC and Clang both struggled to compete with GCC 4.5.0 in the timed HMMer benchmark of a Pfam database search. LLVM-GCC and Clang were about 23% slower.

While using LLVM is faster at building code than GCC (except for the ImageMagick application), in most instances the GCC 4.5 built binaries had performed better than LLVM-GCC or Clang. Clang did deliver a surprising lead over GCC 4.5 and LLVM-GCC with the Apache benchmark where the Clang-built Apache managed to handle 9% more requests per second. There was also significant benefits for LLVM-GCC and Clang with the BYTE Unix Benchmark running the Dhrystone 2 test, but in the rest of the tests the performance was either close to that of GCC or well behind. In some tests, the performance of the Clang generated binaries was simply awful.

Though LLVM / Clang isn't the performance champion at this point, both components continue to be under very active development and there will hopefully be more news to report in the coming months. The LLVM/Clang performance may also certainly improve once more open-source projects begin offering support for detecting and better hooking into Clang. LLVM also does have other advantages over the GNU Compiler Collection that cannot be benchmarked. At the same time though, GCC has the benefits of supporting more hardware targets and hardware optimizations than does LLVM at this point and LLVM also has no plans for supporting Java, Fortran, or some of the other GCC-supported language front-ends. GCC's C++ support is also much more complete than LLVM's Clang at this point.

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 Articles & Reviews
  1. Sub-$20 802.11n USB WiFi Adapter That's Linux Friendly
  2. The Lenovo T450s Is Working Beautifully With Linux
  3. Linux 4.0 SSD EXT4 / Btrfs / XFS / F2FS Benchmarks
  4. Linux 4.0 Hard Drive Comparison With Six File-Systems
  5. Lenovo ThinkPad T450s Broadwell Preview
  6. How Open-Source Allowed Valve To Implement VULKAN Much Faster On The Source 2 Engine
Latest Linux News
  1. GCC 5.1 RC2 Arrives, GCC 5.1 Planned For Next Week
  2. F2FS For Linux 4.1 Has New Features & Fixes
  3. Phoronix Server Upgrade This Weekend: Dual Haswell Xeons, 96GB DDR4
  4. Google's Experimental QUIC Transport Protocol Is Showing Promise
  5. Red Hat Joins Khronos, The Group Behind OpenGL & Vulkan
  6. NetworkManager Drops WiMAX Support
  7. Wine 1.7.41 Works More On Kernel Job Objects, MSI Patches
  8. Linux 4.1 Has Improvements For The Multi-Queue Block Layer
  9. X.Org Looks To Have Six Summer Projects
  10. DragonFlyBSD Pulls In GCC 5 Compiler
Most Viewed News This Week
  1. Nouveau: NVIDIA's New Hardware Is "VERY Open-Source Unfriendly"
  2. Linux 4.0 Kernel Released
  3. Microsoft Announces An LLVM-Based Compiler For .NET
  4. Linux 4.1 Brings Many Potentially Risky x86/ASM Changes
  5. Encryption Support For EXT4
  6. VirtualBox 5.0 Beta 2 Released
  7. Mozilla Start Drafting Plans To Deprecate Insecure HTTP
  8. Elementary OS 0.3 "Freya" Now Available