llvm dev - Sep 2015 - New LLVM backend Target: compile procedure

Hi all,

     I'm trying to get familiar with the LLVM build procedure when adding a
new Target.

     In the main source tree, i copied the  lib/Target/MSP430 as
lib/Target/newUC and renamed all the files.   Further i edited the
different files like Triple.h, Triple.cpp, LLVMBuild.txt, CMakeLists.txt,
CallingConv.h  to take in this new Target.

    Then i deleted the files under the current build/ and started the LLVM
build process anew.

     Is all of this the right way to go about this ?

     I expect i'll make have many issues/fixes to iterate over when
modifying the files for my newTarget. Given, the build takes a long time,
is there a way to do this faster ?  Already been waiting 20mins for it to
finish.


Thanks,
AX
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On 30 September 2015 at 11:46, Sundaran Narayanan via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
>      Is all of this the right way to go about this ?
It all sounds reasonable. Since you're just starting you should be
using the CMake build system (we're trying to get rid of the
llvm/configure script). Make sure it reports finding out about your
directory to avoid wasting time with useless builds.
>      I expect i'll make have many issues/fixes to iterate over when
> modifying the files for my newTarget. Given, the build takes a long time,
is
> there a way to do this faster ?  Already been waiting 20mins for it to
> finish.
When hacking around you usually get a huge saving from doing
incremental builds. Usually just a matter of seconds for modifying
files within your lib/Target/newUC. Modifying Triple.h is still very
bad though and causes an almost complete rebuild.

Just building the tool you're using to test speeds things up even more
"make llc" rather than "make all".

Cheers.

Tim.

On 30/09/15 21:42, Tim Northover via llvm-dev wrote:
> On 30 September 2015 at 11:46, Sundaran Narayanan via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
>>       Is all of this the right way to go about this ?
>
> It all sounds reasonable. Since you're just starting you should be
> using the CMake build system (we're trying to get rid of the
> llvm/configure script). Make sure it reports finding out about your
> directory to avoid wasting time with useless builds.
>
>>       I expect i'll make have many issues/fixes to iterate over
when
>> modifying the files for my newTarget. Given, the build takes a long
time, is
>> there a way to do this faster ?  Already been waiting 20mins for it to
>> finish.
>
> When hacking around you usually get a huge saving from doing
> incremental builds. Usually just a matter of seconds for modifying
> files within your lib/Target/newUC. Modifying Triple.h is still very
> bad though and causes an almost complete rebuild.
>
> Just building the tool you're using to test speeds things up even more
> "make llc" rather than "make all".
>
Disabling some of the target architectures that you don't need also 
helped a lot in link-time for me.

Cheers,
  Roel
> Cheers.
>
> Tim.
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>

> >      I expect i'll make have many issues/fixes to iterate over
when
> > modifying the files for my newTarget. Given, the build takes a long
time, is
> > there a way to do this faster ?  Already been waiting 20mins for it to
> > finish.
There was a lightning talk at EuroLLVM about speeding up the build process. The
slides and recording can be found at http://llvm.org/devmtg/2015-04/, look for
'Building Clang/LLVM efficiently'.

The talk goes into more detail but one of the bigger things you can do in the
cmake build is set BUILD_SHARED_LIBS to ON.

From: llvm-dev [mailto:llvm-dev-bounces at lists.llvm.org] On Behalf Of Sundaran
Narayanan via llvm-dev
Sent: 30 September 2015 19:47
To: llvm-dev at lists.llvm.org
Subject: [llvm-dev] New LLVM backend Target: compile procedure

 Hi all,

     I'm trying to get familiar with the LLVM build procedure when adding a
new Target.

     In the main source tree, i copied the  lib/Target/MSP430 as
lib/Target/newUC and renamed all the files.   Further i edited the different
files like Triple.h, Triple.cpp, LLVMBuild.txt, CMakeLists.txt, CallingConv.h 
to take in this new Target.

    Then i deleted the files under the current build/ and started the LLVM build
process anew.

     Is all of this the right way to go about this ?

     I expect i'll make have many issues/fixes to iterate over when
modifying the files for my newTarget. Given, the build takes a long time, is
there a way to do this faster ?  Already been waiting 20mins for it to finish.


Thanks,
AX




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