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

Unpleasant: LLVM/Clang 3.2 On The ARM Cortex-A15

Compiler

Published on 30 December 2012 05:08 AM EST
Written by Michael Larabel in Compiler
5 Comments

Since publishing LLVM/Clang 3.2 benchmarks a few days ago that showed the Clang C/C++ compiler competing with -- and in some cases outperforming -- the GCC compiler on Intel x86_64, several Phoronix readers have been asking how things compare on the ARM side.

While a few weeks back I published some early benchmarks of GCC vs. LLVM/Clang on the ARM Cortex-A15 using the Samsung Google Chromebook with the Exynos 5 Dual, it seems since the LLVM/Clang 3.0 release, there's some ARMv7 regressions that have come up.

After building the final release of LLVM/Clang 3.2 in the same way to previous LLVM/Clang releases on the same hardware and in a similar manner to other ARM Cotex-A9 development boards, I've been hitting some pain points. With the Samsung Exynos 5 Dual's ARM Cortex-A15, I'm now hitting new problems with LLVM/Clang 3.2 not encountered on the A9 hardware tested. Segmentation faults in Clang have become common in this latest A15 compiler testing on Linux:
4. Running pass 'ARM Instruction Selection' on function '@__cxx_global_var_init'
clang: error: unable to execute command: Segmentation fault (core dumped)
clang: error: clang frontend command failed due to signal (use -v to see invocation)
clang version 3.2 (tags/RELEASE_32/final)
Target: armv7l-unknown-linux-gnueabihf
Thread model: posix
clang: note: diagnostic msg: PLEASE submit a bug report to http://llvm.org/bugs/ and include the crash backtrace, preprocessed source, and associated run script.
clang: note: diagnostic msg:
********************
PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
Preprocessed source(s) and associated run script(s) are located at:
clang: note: diagnostic msg: /tmp/smallpt-z07Dod.cpp
clang: note: diagnostic msg: /tmp/smallpt-z07Dod.sh
clang: note: diagnostic msg:
********************
The Clang segmentation faults have been common within the ARM Instruction Selection pass on this release that came out last week and has occurred for multiple test profiles on different functions. This A15 upset is sad to see with the ARM Cortex-A15 performance being a huge upgrade over the A9-based ARM SoCs.

LLVM 3.2 brought many new features, including on the ARM side, but unfortunately not without some fallout. LLVM/Clang 3.2 benchmarks from ARM Cortex-A9 hardware is forthcoming while it's likely that the Cortex-A15 benchmarks will be delayed to the next release unless a workaround/fix is soon discovered.

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 News
  1. NVIDIA's Proprietary Driver Is Moving Closer With Kernel Mode-Setting
  2. The Latest Linux Kernel Git Code Fixes The EXT4 RAID0 Corruption Problem
  3. Features Added To Mesa 10.6 For Open-Source GPU Drivers
  4. Ubuntu's LXD vs. KVM For The Linux Cloud
  5. Fedora Server 22 Benchmarks With XFS & The Linux 4.0 Kernel
  6. GCC 6 Gets Support For The IBM z13 Mainframe Server
  7. Fedora 22 Is Being Released Next Tuesday
  8. OpenWRT 15.05 Preparing Improved Security & Better Networking
  9. Using The New LLVM/Clang OpenMP Support
  10. Zapcc Claims To Be A "Much Faster C++ Compiler"
Latest Articles & Reviews
  1. Btrfs RAID 0/1 Benchmarks On The Linux 4.1 Kernel
  2. The State Of Various Firefox Features
  3. Intel Iris Graphics Performance With Mesa 10.6
  4. Fedora Workstation 22 Is Looking Great, Running Fantastic
Most Viewed News This Week
  1. The Linux 4.0 Kernel Currently Has An EXT4 Corruption Issue
  2. The Linux 4.0 EXT4 RAID Corruption Bug Has Been Uncovered
  3. AMDGPU Open-Source Driver Code Continues Maturing
  4. Microsoft Open-Sources The Windows Communication Foundation
  5. Another HTTPS Vulnerability Rattles The Internet
  6. LibreOffice 5.0 Open-Source Office Suite Has Been Branched
  7. Systemd 220 Has Finally Been Released
  8. Will Ubuntu Linux Hit 200 Million Users This Year?