Re: [Boost-users] LLVM bitcode for Boost libraries?

Subject: Re: [Boost-users] LLVM bitcode for Boost libraries?
From: Edward Diener (eldiener_at_[hidden])
Date: 2018-11-30 13:59:23

On 11/30/2018 7:47 AM, Osman Zakir via Boost-users wrote:
> So can I pass that flag to b2 when building Boost and have it generate 
> bitcode?  How do I configure the Boost.Build to use LLVM/Clang as the 
> compiler toolchain, though?  On Windows, of course.

You should not top post.

On Windows: If LLVM/clang is targeting vc++, use the clang-win 
toolchain; if LLVM/clang is targeting mingw(-w64)/gcc use the clang 
toolchain.

> ------------------------------------------------------------------------
> *From:* degski <degski_at_[hidden]>
> *Sent:* Friday, November 30, 2018 11:03 AM
> *To:* boost-users_at_[hidden]
> *Cc:* osmanzakir90_at_[hidden]
> *Subject:* Re: [Boost-users] LLVM bitcode for Boost libraries?
> On Thu, 29 Nov 2018 at 18:09, Osman Zakir via Boost-users 
> <boost-users_at_[hidden] <mailto:boost-users_at_[hidden]>> wrote:
> 
>     And what about how to generate LLVM bitcode for Boost libraries? 
>     Can I do it with the bootstrapper tool that comes with the Boost
>     distribution when we download Boost source files?
> 
> 
>   I'm cross-posting this from the cfe-dev list [I know nothing about 
> this, just that the questions seem to be the same]
> 
> Date: Thu, 29 Nov 2018 09:48:58 +0100
> From: Alex Denisov via cfe-dev <cfe-dev_at_[hidden] 
> <mailto:cfe-dev_at_[hidden]>>
> To: David Greene <dag_at_[hidden] <mailto:dag_at_[hidden]>>
> Cc: "cfe-dev_at_[hidden] <mailto:cfe-dev_at_[hidden]>" 
> <cfe-dev_at_[hidden] <mailto:cfe-dev_at_[hidden]>>
> Subject: Re: [cfe-dev] Getting LLVM IR from clang
> Message-ID: <268D2CEC-AFC2-4F32-94FE-E445E882A00D_at_[hidden] 
> <mailto:268D2CEC-AFC2-4F32-94FE-E445E882A00D_at_[hidden]>>
> Content-Type: text/plain;       charset=us-ascii
> 
> Hi David,
> 
> There are at least two robust ways to get the Bitcode/IR:
> 
> 1. LTO. You can enable link-time optimization by adding -flto compiler 
> flags, in the end all object files (*.o) will in fact be bitcode files. 
> I.e.:
> 
>      > file gmock.dir/gmock-gtest-all.cc.o
>      gmock.dir/gmock-gtest-all.cc.o: LLVM bitcode, wrapper x86_6
> 
> 2. Embedded bitcode. Clang 3.9 and higher has an option -fembed-bitcode. 
> When enabled, the resulting executable will contain additional section 
> containing bitcode.
> You can use this great tool[1] to extract the bitcode from an executable.
> 
> Both approaches produce bitcode (binary format), if you need IR 
> (human-readable format), then you can post-process the bitcode by 
> running llvm-dis against each bitcode file.
> 
> I hope it helps.
> 
> [1] https://github.com/JDevlieghere/LibEBC
> 
>  > On 28. Nov 2018, at 23:22, David Greene via cfe-dev 
> <cfe-dev_at_[hidden] <mailto:cfe-dev_at_[hidden]>> wrote:
>  >
>  > How do I get the LLVM IR produced by clang?  I know that -emit-llvm
>  > produces IR but it seems to be after processing by LLVM (things are
>  > optimized out, for example).  Is there an "official" way to get the IR
>  > coming right out of clang's codegen?  I can do a hack with -mllvm
>  > -print-before-all but that's icky.
>  >
>  > Thanks!
>  >
>  >                          -David
>  > _______________________________________________
>  > cfe-dev mailing list
>  > cfe-dev_at_[hidden] <mailto:cfe-dev_at_[hidden]>
>  > http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
> 
> 
> degski
> -- 
> /*/*“*/If something cannot go on forever, it will stop" - Herbert Stein*/
> 
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