llvm dev - Mar 2018 - Proper way to do thinlto (from code)

I'm using llvm-c (but if needed can call c++ stuff too if nedeed);
what's the proper way to emit bitcode with thinlto info so the linker
can parallelize ?I'm currently using: 
unwrap(PMB)->PrepareForThinLTO = b;

on the pass manager builder, but that doesn't seem to be enough?
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You need to make sure that your bitcode file has a module summary index.
You can do that either by creating a WriteBitcodePass with EmitSummaryIndex
set to true or by calling WriteBitcodeToFile with a module summary index
that you created yourself. It doesn't look like either of those options are
hooked up to the c API, though.

Peter

On Fri, Mar 30, 2018, 00:50 Carlo Kok via llvm-dev <llvm-dev at
lists.llvm.org>
wrote:
> I'm using llvm-c (but if needed can call c++ stuff too if nedeed);
what's
> the proper way to emit bitcode with thinlto info so the linker can
> parallelize ?
> I'm currently using:
> unwrap(PMB)->PrepareForThinLTO = b;
>
> on the pass manager builder, but that doesn't seem to be enough?
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
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Thanks! 

I'll create a wrapper for WriteBitcodePass. Do I still need the
PrepareForThinTLO pass or is the writeBitCodePass enough?

On Fri, Mar 30, 2018, at 10:02, Peter Collingbourne
wrote:
> You need to make sure that your bitcode file has a module summary
> index. You can do that either by creating a WriteBitcodePass with
> EmitSummaryIndex set to true or by calling WriteBitcodeToFile with a
> module summary index that you created yourself. It doesn't look like
> either of those options are hooked up to the c API, though.> 
> Peter
> 
> On Fri, Mar 30, 2018, 00:50 Carlo Kok via llvm-dev <llvm-
> dev at lists.llvm.org> wrote:>> __
>> I'm using llvm-c (but if needed can call c++ stuff too if nedeed);
>> what's the proper way to emit bitcode with thinlto info so the
linker
>> can parallelize ?>> I'm currently using: 
>> unwrap(PMB)->PrepareForThinLTO = b;
>> 
>> on the pass manager builder, but that doesn't seem to be enough?
>> _______________________________________________
>>  LLVM Developers mailing list
>> llvm-dev at lists.llvm.org
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
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