linaro-toolchain

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4 participants
5631 discussions

miscompilation of unsigned comparison on aarch64

by Michael Hudson-Doyle

Hi, I filed this on bugzilla: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59744 but I thought I'd mention it here too. This slightly strangely written program (it's distilled down from frame_offset_overflow in the gcc source itself) should print "bigger" if the first argument is bigger than 10 (or negative, but let's ignore that please): #include <stdlib.h> #include <stdio.h> int a[2] = { 10, 20 }; int is_bigger (long offset, int index) { unsigned long size = -offset; if (size > a[index]) { printf("bigger\n"); return 1; } return 0; } int main (int argc, char** argv) { long v; v = atol(argv[1]); is_bigger(-v, 0); return 0; } When compiled at -O1 or above (and with inlining disabled at -O2 and above), though, it bungles the 0 case: (t-doko)mwhudson@arm64:~$ gcc-4.9 -O3 test.c -o test -fno-inline -Wall (t-doko)mwhudson@arm64:~$ ./test 1 (t-doko)mwhudson@arm64:~$ ./test 11 bigger (t-doko)mwhudson@arm64:~$ ./test 0 bigger (t-doko)mwhudson@arm64:~$ gcc-4.9 -O0 test.c -o test -Wall (t-doko)mwhudson@arm64:~$ ./test 1 (t-doko)mwhudson@arm64:~$ ./test 11 bigger (t-doko)mwhudson@arm64:~$ ./test 0 (t-doko)mwhudson@arm64:~$ What's going on? Here's the disassembly of is_bigger (at O3): 0000000000400608 <is_bigger>: 400608: b0000082 adrp x2, 411000 <_GLOBAL_OFFSET_TABLE_+0x28> 40060c: 91010042 add x2, x2, #0x40 400610: a9bf7bfd stp x29, x30, [sp,#-16]! 400614: 52800003 mov w3, #0x0 // #0 400618: 910003fd mov x29, sp 40061c: b8a1d841 ldrsw x1, [x2,w1,sxtw #2] 400620: ab00003f cmn x1, x0 400624: 540000a2 b.cs 400638 <is_bigger+0x30> 400628: 90000000 adrp x0, 400000 <_init-0x3f8> 40062c: 911b6000 add x0, x0, #0x6d8 400630: 97ffff90 bl 400470 <puts@plt> 400634: 52800023 mov w3, #0x1 // #1 400638: 2a0303e0 mov w0, w3 40063c: a8c17bfd ldp x29, x30, [sp],#16 400640: d65f03c0 ret Basically it seems that the condition "-offset > val" is being compiled as "val + offset does not overflow", which is not valid for offset == 0. This seems to me to be the underlying cause behind https://bugs.launchpad.net/ubuntu/+source/gcc-4.8/+bug/1263806 ("gccgo fails to compile tomb.go on arm64"). Cheers, mwh

11 years, 8 months

help on linaro android toolchain 13.12 (arm-v7)

by Sandeepa Prabhu

Hi, We are trying to build android Kitkat (for our own platform) using linaro android toolchain version 4.7.4 from 13.12 release. We are observing following while compiling some shared libraries: ~arm-linux-androideabi-4.7/bin/../libexec/gcc/arm-linux-androideabi/4.7.4/real-ld: warning: shared library text segment is not shareable ~arm-linux-androideabi-4.7/bin/../libexec/gcc/arm-linux-androideabi/4.7.4/real-ld: error: treating warnings as errors We tried to suppress thisn warning by setting LDFLAGS but the tool-chain does not seem to identify this flag: LOCAL_LDFLAGS := --no-warn-shared-textrel We need some help to fix this, so posting on both android and tool-chain mailing lists. Thanks, Sandeepa

11 years, 8 months

LLVM and GCC working together

by Renato Golin

Hi folks, As most of you are on the GNU side of the fence, I believe this is the right crowd to first ask this question, before attempting a wider audience. For a while, Clang/LLVM wasn't in any position to add unheard-of features, and most of what we needed would be covered by something GCC already did. But in the last year or so, there were a number of "features" we'd like to add that aren't present in GCC (like pragmas, attributes, asm directives) which is neither part of the language specifications, nor something that another standard (like OpenMP or ABIs) already support. As a concrete example, we're trying to come up with some vectorisation annotation and there is a heated discussion on whether it should be C++11 attributes, pragmas, or changing the __attribute__ semantics to allow it to be used in lexical blocks, not just declarations. Any of that, but most strikingly the latter, would add Clang-specific behaviour which GCC probably won't implement, and we all know how that feels. In this discussion, and others regarding ARM-specific behaviour (notably about assembly directives), I have used the same argument twice already, so it's time to ask the GCC crowd once and for all: For non-standard, domain or platform specific changes, do we want to have a joint task force, GCC+LLVM, to homogenize the efforts in extending the languages we support in the same say, so that we can call it the "OSS Compiler Extensions" (or whatever) instead of two separate GCC-extensions and Clang-extensions? Historically, GCC has *a lot* more extensions, so this new standard would probably be 99% GCC, but the goals of such a task force for the future would be to: 1. Make sure all OSS compilers implement the same extensions, when they so chose. So, extensions to the language should go in a shared forum, and not to Clang/GCC lists. 2. Document each extension and record all discussions (threads, bugs, etc), so that new compilers can have an easier time implementing them. 3. Reason about the existing hazardous or redundant extensions, and mark them for deprecation. This is also pertinent to the Linux kernel, which is driving its own task force to compiler the kernel with Clang, so that it can rid itself from outdated GNU extensions that lingered for far too long in their code. I appreciate the size of this proposal, the political issues and the endless discussions, but this is the same on every standard committee, and I'd rather have something than nothing at all. Perhaps, as it happened before, some of these changes could be more easily persuaded to move back to the language standards and platforms ABIs, than if it's just implemented, undocumented, by one compiler. So, ignoring just for a moment the political side of it, would that make technical sense for the GCC community as well? cheers, --renato

11 years, 8 months

Stable GCC

by Renato Golin

Folks, Since LLVM is moving on to C++11, I need to replace our buildbot GCCs with 4.7+ (the new minimum requirement), but I'd like to use whatever is the most stable and modern GCC version for native compilation. I could get the latest and greatest on our repository, but I know how compilers are written, and pardon me if I don't trust new releases... ;) Does any one have an opinion on which is the most stable, preferably 4.8, release of native ARMv7 GCC binaries? For some odd reason, we just release cross-compilers, so, in that case, where would I look for a native GCC, other than in my Ubuntu/Arch repositories? ARM? CodeSourcery? I *really* don't want to compile it myself... My lack of available fast ARM hardware is disturbing, and I don't want to spend a week cross-compiling GCC. cheers, --renato

11 years, 8 months

[ANNOUNCE] Linaro GCC 4.8 and 4.7 2013.12 released

by Christophe Lyon

The Linaro Toolchain Working Group is pleased to announce the release of both Linaro GCC 4.8 and Linaro GCC 4.7. Linaro GCC 4.7 2013.12 is the twentiy first release in the 4.7 series. Based off the latest GCC 4.7.4+svn205768 release, this is the eighth release after entering maintenance. Interesting changes include: * Updates to GCC 4.7.4+svn205768 * Fixed MULTILIB_DEFAULTS in linux-eabi case. Linaro GCC 4.8 2013.12 is the ninth release in the 4.8 series. Based off the latest GCC 4.8.3+svn205577 release, it includes performance improvements and bug fixes. Interesting changes include: * Updates to GCC 4.8.3+svn205577 * AArch64: enable build of libjava and libatomic. Change frame growth direction, thus enabling libssp build. The source tarballs are available from: http://releases.linaro.org/13.12/components/toolchain/gcc-linaro/4.7 http://releases.linaro.org/13.12/components/toolchain/gcc-linaro/4.8 Downloads are available from the Linaro Releases website: http://www.linaro.org/downloads/ More information on the features and issues are available from the release pages: https://launchpad.net/gcc-linaro/4.7/4.7-2013.12 https://launchpad.net/gcc-linaro/4.8/4.8-2013.12 Mailing list: http://lists.linaro.org/mailman/listinfo/linaro-toolchain Bugs: https://bugs.launchpad.net/gcc-linaro/ Questions? https://ask.linaro.org/ Interested in commercial support? Inquire at support(a)linaro.org

11 years, 8 months

[Activity] 30 DEC-03 Jan 2013

by Venkataramanan Kumar

== Progress == * Pointer mangling Aarch64 glibc. Worked on review comments from Maintainer. Rebased and posted the patch. Upstream completed and closed the card. https://cards.linaro.org/browse/TCWG-373 * Experimented with Cbuildv2 native building. == Plan == - Continue Cbuildv2. - Investigate PGO for Aarch64. == Issues == Waiting for feedback on libssp machine descriptions changes.

11 years, 8 months

[ACTIVITY] Week 01

by Zhenqiang Chen

== Issues == * None == Progress == * One day off (Jan. 1) * Do some basic validations for 2013.12 toolchain binaries release. * R/M Mac toolchain validation * Branch-cost related tuning for Cortex-M. == Plans == * Continue on branch-cost related tuning.

11 years, 8 months

[ACTIVITY] 30 December 2013 - 3rd January 2014

by Kugan

== Progress == - Short week (4 Days) - TCWG-291 zero/sign extension elimination 4/10 - made re-factoring and ran the regression - benchmarking in progress - TCWG-134 divmod 4/10 - converted into latest pass structure and re-based the patch - found some regression failures and fixed them - regression testing ongoing == Plan == - post divmod and vrp patches

11 years, 8 months

[ACTIVITY] 30 December 2013 - 3rd January 2014

by Omair Javaid

== Progress == * ARM Process Record: [TCWG-336] [TCWG-338] [TCWG-339][TCWG-317] [TCWG-315] - Configured and learnt to use git format-patch and git send-email. [1/10] - Incorporated and tested changes suggested by maintainers in previous arm process record patches. [2/10] - Created a new patch series indicating bug fixes separate from features. [1/10] - Submitted version 2 of arm process record replay improvements. * Debugging of stepping over and single stepping heurisitic code. [TCWG-315] [4/10] * Review of open JIRA cards and pending patches [1/10] * Time off for setting up new office space. [0.5/10] * Macau visa information gathering and document preparation [0.5/10] == Plan == * Reverse engineering stepping code heuristics in gdb to find a fix for reverse debugging of solib code on arm. [TCWG-315] * Find and submit a new fix for TCWG-267. * New office space setup and Macau visa application, will be away from my desk for few hours.

11 years, 8 months

[ANNOUNCE] Linaro Toolchain Binaries 2013.12 released

by Bernhard Rosenkränzer

Just before having to rename it to 2014, the Linaro Toolchain and Builds and Baselines Working Groups are pleased to announce the 2013.12 release of the Linaro Toolchain Binaries, a pre-built version of Linaro GCC and Linaro GDB that runs on generic Linux or Windows and targets the glibc Linaro Evaluation Build. Uses include: * Cross compiling ARM applications from your laptop * Remote debugging * Build the Linux kernel for your board What's included: * Linaro GCC 4.8 2013.12 * Linaro GDB 7.6.1 2013.12 * Linaro Binutils 2.24 2013.12 * A statically linked gdbserver * A system root * Manuals under share/doc/ The system root contains the basic header files and libraries to link your programs against. Interesting changes include: * Binutils has been updated to 2.24, bringing many improvements * Various bugs have been fixed The Linux version is supported on Ubuntu 10.04.3 and 12.04, Debian 6.0.2, Fedora 16, openSUSE 12.1, Red Hat Enterprise Linux Workstation 5.7 and later, and should run on any Linux Standard Base 3.0 compatible distribution. Please see the README about running on x86_64 hosts. The Windows version is supported on Windows XP Pro SP3, Windows Vista Business SP2, and Windows 7 Pro SP1. The binaries and build scripts are available from: https://releases.linaro.org/13.10/components/toolchain/binaries/ Need help? Ask a question on https://ask.linaro.org/ Already on Launchpad? Submit a bug at https://bugs.launchpad.net/linaro-toolchain-binaries On IRC? See us on #linaro on Freenode. Other ways that you can contact us or get involved are listed at https://wiki.linaro.org/GettingInvolved.

11 years, 8 months

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