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

What's Exciting About LLVM 3.0 & The New Clang

Compiler

Published on 29 November 2011 11:46 AM EST
Written by Michael Larabel in Compiler
2 Comments

Version 3.0 of LLVM is expected to be released tomorrow, along with a major update to Clang. Here's some of the noteworthy enhancements.

LLVM 3.0 with the adjoining Clang update is the first major update to the Low-Level Virtual Machine since the LLVM 2.9 release last April. LLVM 3.0 was scheduled for a November release (but it was delayed slightly) and marks the point of deprecating LLVM-GCC in favor of DragonEgg, which allows for LLVM optimizers to be used with the mainline GCC compiler front-end via a unique plug-in. Other interesting changes for LLVM 3.0 are listed below.

Clang C/C++ Compiler In LLVM 3.0:

- Much-improved C++ support in building software, the stability of the built software, and the diagnostics of any C++ issues.

- Improved C++0x (C++ 2011) support, but it's still not feature complete.

- Support for some features in the upcoming C1x standard.

- Improved Objective-C support.

DragonEgg For LLVM 3.0:

- GCC 4.6 is now fully supported by this plug-in to replace the GCC optimizers with those from LLVM.

- DragonEgg no longer requires a patched GCC but the plug-in can be cleanly loaded from GCC mainline versions 4.5/4.6.

- The option that allows both the GCC and LLVM optimizers to be used (rather than outright replacing the GCC optimizers with those of LLVM). This option is designed to deliver the "ultimate performance" but is still deemed experimental. (I'll be benchmarking out the new DragonEgg soon.)

- C, C++, Fortran, and ADA remain the officially supported languages for this GCC-front-end with LLVM-back-end plug-in. There's partial support for Java, Objective-C, Objective-C++, and Google Go.

Other LLVM Changes:

- libc++ (the new C++ standard library) and compiler_rt are now dual-licensed under the MIT and UIUC licenses. The LLVM C++ standard library is expected to be the default STL implementation in FreeBSD 10.0.

- VMKit (A Java Virtual Machine for LLVM) now supports pre-compilation, customized virtual methods, better inlining support, and a new exception model.

- LLVM IR now has full support for atomic memory operations as needed to support C++11 (C++0x) and C1x.

- A new "greedy" register allocator replaces the linear-scan register allocator.

- There's significant improvements to the MIPS back-end in LLVM 3.0.

- The MIPS architecture back-end to LLVM has been greatly improved.

- AVX (version 1) is now supported by LLVM, this is the Advanced Vector Extensions as introduced in the AMD Bulldozer and Intel Sandy Bridge CPUs.

- The Assembler/Disassembler has a range of new instructions for Intel Atom, Intel Ivy Bridge, SSE4a/BMI, rdrand, and others.

- Significant performance improvements for ARM Cortex-A9 SOCs. There's also improved Cortex-M series support and performance improvements for ARM NEON code.

More details about the imminent release of LLVM 3.0 can be found on the release notes page. I have already published some LLVM/Clang 3.0 benchmarks but more will be on the way from a greater range of systems and also in benchmarking the DragonEgg plug-in.

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. Btrfs On 4 x Intel SSDs In RAID 0/1/5/6/10
  2. AMD Radeon R9 290 On Ubuntu 14.10: RadeonSI Gallium3D vs. Catalyst
  3. MSI X99S SLI PLUS On Linux
  4. NVIDIA GeForce GTX 970 Offers Great Linux Performance
Latest Linux Articles
  1. NVIDIA's Linux Driver Can Deliver Better OpenGL Performance Than Windows 8.1
  2. Windows 8.1 vs. Ubuntu 14.10 With Intel HD Graphics
  3. 6-Way Ubuntu 14.10 Radeon Gallium3D vs. Catalyst Driver Comparison
  4. NVIDIA vs. Nouveau Drivers On Ubuntu 14.10
Latest Linux News
  1. Wine 1.7.30 Continues Work On DirectWrite & Offers Regedit Fixes
  2. Has The Sky Fallen? Qualcomm Contributes To Freedreno's DRM/KMS Driver
  3. Manjaro Works To Make Calamares A Distribution-Independent Installer
  4. DisplayLink USB 3.0 Support Sounds Like A Mess
  5. PulseAudio Gains A Native Bluetooth Headset Backend
  6. X.Org Foundation Decides On Its Women Outreach Project
  7. GTK+ 3.16's New GtkGLArea Widget Gets Improved
  8. X.Org Server 1.17 ABI Bumped
  9. Fedora 21 Beta To Be Released Next Week
  10. Go 1.4 Beta Release Brings Big Runtime Changes
Latest Forum Discussions
  1. How to get rid of Linux
  2. Closed source to opensource
  3. What Would You Like To See Next?
  4. Is foolish currently develop in machine code, hexadecimal and assembly?
  5. Reducing The CPU Usage In Mesa To Improve Performance
  6. Help diagnosing problems with a Readon HD 4670 on Mesa 10.3.2-1
  7. Advertisements On Phoronix
  8. nv and xorg.conf under Debian PPC