llvm dev - Nov 2012 - [LLVMdev] [compiler-rt] is the arm lib complete?

On Nov 15, 2012, at 9:33 PM, liangh at codeaurora.org
wrote:
> I'm trying to link my objs with compiler-rt built runtime lib for arm.
> According to the compiler-rt doc, it should be able to replace libgcc.
> However, if I replace "-lgcc" with "compiler-rt.a" for
a static linking,
> gcc linker complains about undefined functions. Using "nm -g", I
compared
> the functions in libgcc and compiler-rt.full-arm.a and found there are
> many missing functions in compiler-rt, such as "__aeabi_dcmpeq"
> "__sync_lock_release_1" "_interwork_call_via_fp", etc.
> 
> Although I can use compiler-rt.a via using
"-allow-multiple-definition" to
> override libgcc, this is an ugly solution.
> 
> Anybody know how to fully replace libgcc with compiler-rt? Do I need to
> link some other lib to totally replace libgcc when using compiler-rt, or
> compiler-rt cannot fully replace libgcc yet? I know Apple is using
> compiler-rt built runtime libs. How did they link?
What compiler are you using?  compiler-rt was designed to implement the support
functions needed for clang.  If you are compiling with gcc, then, yes you might
find it relies on support functions not in libcompiler-rt.a.

-Nick

I'm using Clang, with arm-none-linux-gnueabi-g++ as a linker. Although
compiler-rt replaced libgcc, we still need other libs such as libc, libm,
etc. It seems libc is calling these missing functions.
>
> On Nov 15, 2012, at 9:33 PM, liangh at codeaurora.org wrote:
>> I'm trying to link my objs with compiler-rt built runtime lib for
arm.
>> According to the compiler-rt doc, it should be able to replace libgcc.
>> However, if I replace "-lgcc" with "compiler-rt.a"
for a static linking,
>> gcc linker complains about undefined functions. Using "nm
-g", I
>> compared
>> the functions in libgcc and compiler-rt.full-arm.a and found there are
>> many missing functions in compiler-rt, such as
"__aeabi_dcmpeq"
>> "__sync_lock_release_1" "_interwork_call_via_fp",
etc.
>>
>> Although I can use compiler-rt.a via using
"-allow-multiple-definition"
>> to
>> override libgcc, this is an ugly solution.
>>
>> Anybody know how to fully replace libgcc with compiler-rt? Do I need to
>> link some other lib to totally replace libgcc when using compiler-rt,
or
>> compiler-rt cannot fully replace libgcc yet? I know Apple is using
>> compiler-rt built runtime libs. How did they link?
>
> What compiler are you using?  compiler-rt was designed to implement the
> support functions needed for clang.  If you are compiling with gcc, then,
> yes you might find it relies on support functions not in libcompiler-rt.a.
>
> -Nick
>
>

> I'm using Clang, with arm-none-linux-gnueabi-g++ as a linker. Although
> compiler-rt replaced libgcc, we still need other libs such as libc, libm,
> etc. It seems libc is calling these missing functions.
If you compile libc with gcc, then yes, you might need arbitrary
functions from libgcc.

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