llvm dev - Jul 2012 - [LLVMdev] Setting up a cross-compiler for cortex-m3

On 18 July 2012 15:46, salvatore benedetto
<salvatore.benedetto at gmail.com> wrote:
> $ clang++ -ccc-host-triple thumbv7m-none-gnueabi noInclude.cpp -c
>
--sysroot=/home/emitrax/CodeSourcery/Sourcery_G++_Lite/arm-none-linux-gnueabi/libc/
Try -ccc-gcc-name arm-none-linux-gnueabi-g++ -ccc-host-triple
thumbv7m-none-linux-gnueabi

Sometimes it's better than sysroot, as it finds it all by itself.

-- 
cheers,
--renato

http://systemcall.org/

On Wed, Jul 18, 2012 at 5:45 PM, Renato Golin <rengolin at systemcall.org>
wrote:
> On 18 July 2012 15:46, salvatore benedetto
> <salvatore.benedetto at gmail.com> wrote:
>> $ clang++ -ccc-host-triple thumbv7m-none-gnueabi noInclude.cpp -c
>>
--sysroot=/home/emitrax/CodeSourcery/Sourcery_G++_Lite/arm-none-linux-gnueabi/libc/
>
> Try -ccc-gcc-name arm-none-linux-gnueabi-g++ -ccc-host-triple
> thumbv7m-none-linux-gnueabi
>
> Sometimes it's better than sysroot, as it finds it all by itself.
And the winner is..

clang++ -ccc-gcc-name arm-none-linux-gnueabi-g++ -ccc-host-triple
thumbv7m-none-gnueabi testReference.cpp -c

It seems like it worked.

$ arm-none-linux-gnueabi-objdump -D --section=.text testReference.o

testReference.o:     file format elf32-littlearm


Disassembly of section .text:

00000000 <main>:
   0:	e92d4800 	push	{fp, lr}
   4:	e1a0b00d 	mov	fp, sp
   8:	e24dd030 	sub	sp, sp, #48	; 0x30
...

I'm not 100% sure if that's the correct ISA, because I haven't run
the
code, but it seems ok.

I of course own you a beer :-) Thank you very much.

Now, a grep of clang++ --ccc-gcc-name didn't give any result so I'm
still wondering what
exactly I am doing here.

Which part of gcc I'm using with that option?
Just the libc, libgcc et all?

Regards,
S.

On 18 July 2012 17:08, salvatore benedetto
<salvatore.benedetto at gmail.com> wrote:
> I of course own you a beer :-) Thank you very much.
I will remind you of that, next year, on EuroLLVM 2013. :D

> Which part of gcc I'm using with that option?
> Just the libc, libgcc et all?
AFAIK, it uses the name to find the tool chain, and guess all other
binaries from it. So it calls arm-linux-gnueabi-ld,
arm-linux-gnueabi-as etc. instead of ld, as etc., which is what you
were missing.

-- 
cheers,
--renato

http://systemcall.org/

On Wed, Jul 18, 2012 at 6:08 PM, salvatore benedetto
<salvatore.benedetto at gmail.com> wrote:
> On Wed, Jul 18, 2012 at 5:45 PM, Renato Golin <rengolin at
systemcall.org> wrote:
>> On 18 July 2012 15:46, salvatore benedetto
>> <salvatore.benedetto at gmail.com> wrote:
>>> $ clang++ -ccc-host-triple thumbv7m-none-gnueabi noInclude.cpp -c
>>>
--sysroot=/home/emitrax/CodeSourcery/Sourcery_G++_Lite/arm-none-linux-gnueabi/libc/
>>
>> Try -ccc-gcc-name arm-none-linux-gnueabi-g++ -ccc-host-triple
>> thumbv7m-none-linux-gnueabi
>>
>> Sometimes it's better than sysroot, as it finds it all by itself.
>
> And the winner is..
>
> clang++ -ccc-gcc-name arm-none-linux-gnueabi-g++ -ccc-host-triple
> thumbv7m-none-gnueabi testReference.cpp -c
>
> It seems like it worked.
>
> $ arm-none-linux-gnueabi-objdump -D --section=.text testReference.o
>
> testReference.o:     file format elf32-littlearm
>
>
> Disassembly of section .text:
>
> 00000000 <main>:
>    0:   e92d4800        push    {fp, lr}
>    4:   e1a0b00d        mov     fp, sp
>    8:   e24dd030        sub     sp, sp, #48     ; 0x30
> ...
>
> I'm not 100% sure if that's the correct ISA, because I haven't
run the
> code, but it seems ok.
>
Unfortunately, I have to resurrect this thread.

I had the time to test the code, and it is using the wrong ISA.
I can't understand why, but it uses armv5te instead of thumb2.

$ clang++ -ccc-gcc-name arm-none-linux-gnueabi-g++ -ccc-host-triple
thumbv7m-none-gnueabi testReference.cpp -c
$ arm-none-linux-gnueabi-readelf -A testReference.o
Attribute Section: aeabi
File Attributes
  Tag_CPU_name: "5TE"
  Tag_CPU_arch: v5TE
  Tag_ARM_ISA_use: Yes
  Tag_THUMB_ISA_use: Thumb-1
  Tag_ABI_FP_denormal: Needed
  Tag_ABI_FP_exceptions: Needed
  Tag_ABI_FP_number_model: IEEE 754
  Tag_ABI_align_needed: 8-byte
  Tag_ABI_align_preserved: 8-byte, except leaf SP
  Tag_DIV_use: Not allowed

I realized this only when I moved to compile my firmware and
got the following

/tmp/startup-EFUAJp.s: Assembler messages:
/tmp/startup-EFUAJp.s:84: Error: width suffixes are invalid in ARM
mode -- `ldr.w sp,[r0]'

Using the -v options produce the following

gcc version 4.6.3 (Sourcery CodeBench Lite 2012.03-57)
COLLECT_GCC_OPTIONS='-ffunction-sections' '-fno-common'
'-fno-exceptions' '-fno-rtti' '-v' '-nostdlib'
'-nodefaultlibs'
'-Wall' '-stdlib=libc++' '-I'
'/home/emitrax/bin/llvm/lib/c++/v1'
'-std=c++11' '-I'
'/home/emitrax/programming/adok/build/include/private' '-I'
'/home/emitrax/programming/adok/include/private' '-c'
'-o'
'source/porting/arch/arm/cortex-m3/stack.cpp.o' '-shared-libgcc'
'-march=armv5te' '-mtls-dialect=gnu' '-D'
'__CS_SOURCERYGXX_MAJ__=2012' '-D'
'__CS_SOURCERYGXX_MIN__=3' '-D'
'__CS_SOURCERYGXX_REV__=57'

Any suggestions?

Regards,
S.