llvm dev - Sep 2013 - [LLVMdev] adding new target to configure script

I'm experimenting with a new backend, hoping to build a cross compiler, and
reading "Writing an LLVM Compiler Backend". Early on, in
"Preliminaries",
it suggests editing my configure script to add my new target to the
TARGETS_TO_BUILD variable, suggesting some creativity may be required.

I'm perhaps not creative enough, 'cause I can't get it to work. I
tried a
couple of variations (one seemed straightforward; in the other, I went
through looking for every example of Sparc to see how they did it and
making the appropriate changes).

I tried configuring like this

    ./configure --enable-target=preston --disable-optimized
--enable-assertions=yes --prefix=/path-to-install

and it chunked along for a while, but ultimately failed, complaining

    configure: error: Unrecognized target preston
    configure: error: ./configure failed for projects/sample

Any ideas?

Thanks,
Preston
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On Wed, Sep 04, 2013 at 02:00:13PM -0700, Preston Briggs
wrote:
> I'm experimenting with a new backend, hoping to build a cross compiler,
and
> reading "Writing an LLVM Compiler Backend". Early on, in
"Preliminaries",
> it suggests editing my configure script to add my new target to the
> TARGETS_TO_BUILD variable, suggesting some creativity may be required.
> 
If you configure with --enable-experimental-targets=Preston assuming
that your backend is in lib/Target/Preston and you have updated all the
LLVMBuild.txt files, then you should be able to build your backend
without updating the configure script.
> I'm perhaps not creative enough, 'cause I can't get it to work.
I tried a
> couple of variations (one seemed straightforward; in the other, I went
> through looking for every example of Sparc to see how they did it and
> making the appropriate changes).
> 
> I tried configuring like this
> 
>     ./configure --enable-target=preston --disable-optimized
> --enable-assertions=yes --prefix=/path-to-install
> 
> and it chunked along for a while, but ultimately failed, complaining
> 
>     configure: error: Unrecognized target preston
>     configure: error: ./configure failed for projects/sample
> 
Did you update the configure script in projects/sample ?

-Tom