[LLVMdev] Enable soft-float

[Xun Li]

On Thu, Mar 31, 2011 at 6:47 PM, John Criswell <criswell at illinois.edu> wrote:
> On 3/31/11 8:39 PM, Xun Li wrote:
>>
>> Hi All,
>>
>> I am working on a custom defined architecture which implements Sparc
>> ISA but without floating point instructions.
>> I have two questions regarding using LLVM:
>> 1. How to enable soft-float when building llvm-gcc?
>
> There might be an option when configuring llvm-gcc.  Check the GCC docs to
> see if such an option exists.  Maybe someone who has used LLVM on Sparc
> recently can comment.
>

Thanks.
It seems to me that soft-float is generated at the backend, i.e. there
are soft-float options when building binutils for gcc.
But now llvm-gcc is only a frontend and llvm takes care of the
backend. If llvm is not supporting soft-float then I am out of luck.

>> 2. How to let llvm-gcc generate native code (binaries) for Sparc? Do I
>> have to compile glibc or newlib for Sparc and link with it together?
>> I am kinda confused so it would be great if anyone could offer some help.
>
> llvm-gcc assumes that there's already a native code C library available to
> use.  All the systems of which I know already come with a C library.  If you
> somehow don't have a C library for your system, you'll have to compile one.
>

Yes every system comes with C library implementations but if the
target architecture is different from the host, e.g. I am running llvm
on x86 but I am generating code for sparc then I won't have libraries
directly available. Is that right? How do people normally handle this?

> -- John T.
>
>> Thanks!
>>
>
>



-- 
Xun Li
Computer Architecture Lab
Department of Computer Science
University of California, Santa Barbara