llvm dev - Jun 2010 - [LLVMdev] build errors while cross compiling llvm-gcc for ARM

> Sorry about that.  As you can see, I'm using binutils (ld & as )
from arm
> toolchain we use to build things for our target.
>
> arm_a_b_c_ld -v gives 2.17.50.20070611
>
> arm_a_b_c_as -v gives 2.17.50.20070611
This is definitely not the latest binutils you've stated before. As
you might see - these are at least 3 years old and are known to be
heavily buggy on ARM.
> Do you belive that older binaries of (linker & assembler) can cause
performance drop ?
No. They are just buggy (at least assembler).
> Unfortunately I'm not in a position to update the arm compiler for my
company :)
Well, sorry, then you're not lucky then. You should expect invalid
code / spurious error messages produced in many places (and you
already saw this!)

-- 
With best regards, Anton Korobeynikov
Faculty of Mathematics and Mechanics, Saint Petersburg State University

Thanks, last doubt :)

But I wanted to say is using these binutils I have built a llvm compiler for
our ARM target.

Now our libraries which are either compiled with native ARM or with this
llvm compiler gives same performance numbers. However this only llvm
compiler if compared with x86 compiler gives huge performance gain.

Any idea why this might be happening ?

On Mon, Jun 28, 2010 at 1:57 PM, Anton Korobeynikov <anton at
korobeynikov.info
> wrote:
> > Sorry about that.  As you can see, I'm using binutils (ld & as
) from arm
> > toolchain we use to build things for our target.
> >
> > arm_a_b_c_ld -v gives 2.17.50.20070611
> >
> > arm_a_b_c_as -v gives 2.17.50.20070611
> This is definitely not the latest binutils you've stated before. As
> you might see - these are at least 3 years old and are known to be
> heavily buggy on ARM.
>
> > Do you belive that older binaries of (linker & assembler) can
cause
> performance drop ?
> No. They are just buggy (at least assembler).
>
> > Unfortunately I'm not in a position to update the arm compiler for
my
> company :)
> Well, sorry, then you're not lucky then. You should expect invalid
> code / spurious error messages produced in many places (and you
> already saw this!)
>
> --
>  With best regards, Anton Korobeynikov
> Faculty of Mathematics and Mechanics, Saint Petersburg State University
>
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> But I wanted to say is using these binutils I have built a llvm compiler
for
> our ARM target.
That's correct. Mostly because gcc is using pre-UAL ARM assembler syntax
and LLVM switched fully to UAL one. Also, UAL is needed for correct Thumb-2
support, etc. So, in short: gcc is generating some subset of ARM assembler
and thus gas is bug-free. LLVM generates somehow different subset and this
uncovered many bugs inside gas :)
> Now our libraries which are either compiled with native ARM or with this
> llvm compiler gives same performance numbers. However this only llvm
> compiler if compared with x86 compiler gives huge performance gain.
You mean that llvm-generated code is faster on x86, but not on ARM compared
to the vendor compiler / gcc, right?

-- 
With best regards, Anton Korobeynikov
Faculty of Mathematics and Mechanics, Saint Petersburg State University