[LLVMdev] build errors while cross compiling llvm-gcc for ARM

Sanjeev chugh sanjuchugh at gmail.com
Thu Jun 24 22:03:21 PDT 2010


Any help would b appreicated. This is one of my critical assignment.


On Thu, Jun 17, 2010 at 7:03 PM, Sanjeev chugh <sanjuchugh at gmail.com> wrote:

> Hello,
> Thanks for the reply. We have an product whose one part has lot of
> algorithms doing some graphics work. Our intention was to figure out if
> there can be any performance gain if we use llvm instead of native ARM. This
> is for ARM target. Earlier, I have built this component using llvm and
> tested  it on x86. Performance was 4x as compared to native gcc. Then I
> built llvm for ARM and tested this component on ARM with llvm compiler and
> performance of llvm+arm against native ARM was almost equal or less :(
> However, I have run a simple sorting algorithms who run for 100K times and
> sort 10K elements on llvm+arm and this time it's performance was 3x better
> than native ARM. Can you guys please suggest what could be there in this
> graphics component which is not allowing the performance to improve for
> ARM+llvm.
> cross-compiler has been built with these flags
> Using built-in specs.
> Target: armv7fl-montavista-linux-gnueabi
> Configured with: ./configure --host=i686-pc-linux-gnu
> --build=i686-pc-linux-gnu --target=armv7fl-montavista-linux-gnueabi
> --enable-cross --with-sysroot=/home/arm_v7_vfp_le/target/
> --with-build-sysroot=/home/arm_v7_vfp_le/target/ --enable-shared
> --enable-languages=c,c++ --with-as=/home/arm_v7_vfp_le/bin/arm_v7_vfp_le-as
> --with-ld=/home/arm_v7_vfp_le/bin/arm_v7_vfp_le-ld --enable-checking=release
> --disable-multilib --enable-llvm=/home/Desktop/Sanjeev/LLVM/llvm-2.7
> --enable-clocale=gnu --with-cpu=cortex-a8 --with-interwork
> --with-arch=armv7-a --with-mode=arm --with-tune=cortex-a8 --with-fpu=vfp3
> --disable-bootstrap --disable-libmudflap --disable-libssp
> Thread model: posix
> gcc version 4.2.1 (Based on Apple Inc. build 5658) (LLVM build)
> These are the steps how I'm building library on ARM+llvm. generated .a is
> linked with other targets built with native arm compiler.
> g++-cross -flto -O2 -Wall -function-sections -fdata-sections ; for all
> .cpps
> llvm-ld -link-as-library *.bc target.bc // Consolidate all .bcs into one
> llc target.bc -o target.s
> cross-as target.s -o target.o
> ar q target.a target.o
>   On Mon, Jun 7, 2010 at 10:18 PM, Anton Korobeynikov <
> anton at korobeynikov.info> wrote:
>> Hello
>> > /tmp/cczBL31y.s:409: rdhi, rdlo and rm must all be different
>> This is binutils bug fixed ~2 years ago:
>> http://sourceware.org/ml/binutils/2007-11/msg00046.html
>> Make sure you're using the latest binutils for ARM (from binutils CVS)
>> --
>> With best regards, Anton Korobeynikov
>> Faculty of Mathematics and Mechanics, Saint Petersburg State University
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