[cfe-dev] How to add new target?

[Artur Pietrek]

On Tue, Mar 30, 2010 at 2:25 PM, Artur Pietrek <pietreka at gmail.com> wrote:

> On Thu, Mar 25, 2010 at 4:21 PM, Daniel Dunbar <daniel at zuster.org> wrote:
>
>> On Thu, Mar 25, 2010 at 5:33 AM, Artur Pietrek <pietreka at gmail.com>
>> wrote:
>> >> Hi Artur,
>> >
>> > Hi Daniel
>> >
>> >>
>> >> > Hi all,
>> >> > so after "greping" the code I was able to do (more or less)
>> everything I
>> >> > wanted to do.
>> >>
>> >> As you have discovered, this stuff isn't very well documented yet. Do
>> >> you feel like writing up a blurb we could add to our Internals Manual
>> >> describing what you have discovered?
>> >
>> > I'll try when I'll make it work correct ;)
>> >
>> > BTW I've noticed strange behaviour. When I switched from llvm-gcc to
>> clang,
>> > my benchmarks stopped working. When I compile simple code:
>> >
>> > char array[] =
>> > "+0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ_abcdefghijklmnopqrstuvwxyz";
>> >
>> > int main() {
>> >   return array[31];
>> > }
>> >
>> > like this:
>> > clang -ccc-host-triple mycpu -O0 -S hello.c -o hello.s
>> >
>> > The code is wrong, to be precise in one instruction I get
>> > lbs $r16 = 0[$r17] instead of lbs $r16 = 31[$r17]
>> >
>> > but the code is correct when I do it like this:
>> > clang -ccc-host-triple mycpu -O0 hello.c -c -emit-llvm -o hello.bc
>> > llc -march=mycpu hello.bc -o hello.s
>> >
>> >
>> > Am I missing something? Shouldn't these two be equivalent?
>>
>> Unfortunately, no. The driver sets a variety of options in the LLVM
>> backend that you would need to pass to llc by hand. Try running
>> $ clang -ccc-host-triple mycpu -O0 hello.c -c -emit-llvm -o hello.bc -###
>> to see how clang is calling the compiler (clang -cc1), and look for -m
>> arguments. For example, -mcpu sets the CPU to target, and other -m
>> options do things like disable use of a frame pointer.
>>
>>  - Daniel
>>
>
> Thanks for advice, there was a bug in relocation in my backend and indeed
> clang was triggering it by passing different options than llc.
>
> Now I'm trying to find another bug. I don't know why I'm ending up with reg
> to reg copy from 64bit to 32bit register class but only using clang and
> turned on optimization (when i compile with llvm-gcc or again with clang to
> bitcode and then using llc the problem does not occur).
> I've tried to change options given to compiler, but this changes nothing.
> The code I try to compile has castings from i8* to i64*.
> Any ideas what could trigger that?
> Is there a way to force clang to dump debug information similar to "llc
> -debug"?
>

So forget about that 64bit to 32bit question. It was a bug in conditional
branch implementation.

But still, is there a way to produce the debug output with clang as with
llc?

Thanks
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/cfe-dev/attachments/20100330/1534942e/attachment.html>