[llvm-dev] Why do we static link all llvm libraries in every executable?

[Yin Ma via llvm-dev]

Hi

 

I found basically all llvm libraries are statically linked into each executable and LLVMgold.so,

This make the clang/llvm package larger and larger with a lot of duplicated code. If I build

debug version, the disk space required is even larger. Is there any particular reason to keep

doing this way? If we separate several shared libraries something like libclang.so, libllvm.so

and let all executables and llvmgold.so just linked with .so. A lot of space could be saved and

loading performance could be improved.

 

Yin

[Joerg Sonnenberger via llvm-dev]

On Mon, Jan 25, 2016 at 10:13:35AM -0800, Yin Ma via llvm-dev wrote:
> If we separate several shared libraries something like
> libclang.so, libllvm.so and let all executables and llvmgold.so just
> linked with .so. A lot of space could be saved and
> loading performance could be improved.

There is a build option to do exactly that. It comes at a significant
price for startup, e.g. clang will take 10x as long for building a small
example.

Joerg
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[serge guelton via llvm-dev]

On Mon, Jan 25, 2016 at 07:16:20PM +0100, Joerg Sonnenberger via llvm-dev wrote:
> On Mon, Jan 25, 2016 at 10:13:35AM -0800, Yin Ma via llvm-dev wrote:
> > If we separate several shared libraries something like
> > libclang.so, libllvm.so and let all executables and llvmgold.so just
> > linked with .so. A lot of space could be saved and
> > loading performance could be improved.
>
> There is a build option to do exactly that. It comes at a significant
> price for startup, e.g. clang will take 10x as long for building a small
> example.

Namely BUILD_SHARED_LIBS=ON

I find it very useful for dev builds!

[Yury Gribov via llvm-dev]

On 01/25/2016 09:16 PM, Joerg Sonnenberger via llvm-dev wrote:
> On Mon, Jan 25, 2016 at 10:13:35AM -0800, Yin Ma via llvm-dev wrote:
>> If we separate several shared libraries something like
>> libclang.so, libllvm.so and let all executables and llvmgold.so just
>> linked with .so. A lot of space could be saved and
>> loading performance could be improved.
>
> There is a build option to do exactly that. It comes at a significant
> price for startup, e.g. clang will take 10x as long for building a small
> example.

Is this to process runtime relocations or run constructors? I wonder if
Prelink or ElfHack could help.

[David Blaikie via llvm-dev]

On Tue, Jan 26, 2016 at 12:44 AM, Yury Gribov via cfe-dev <cfe...@lists.llvm.org> wrote:

On 01/25/2016 09:16 PM, Joerg Sonnenberger via llvm-dev wrote:

On Mon, Jan 25, 2016 at 10:13:35AM -0800, Yin Ma via llvm-dev wrote:

If we separate several shared libraries something like
libclang.so, libllvm.so and let all executables and llvmgold.so just
linked with .so. A lot of space could be saved and
loading performance could be improved.

There is a build option to do exactly that. It comes at a significant
price for startup, e.g. clang will take 10x as long for building a small
example.

Is this to process runtime relocations or run constructors? I wonder if Prelink or ElfHack could help.

Runtime relocations, I would imagine (global ctors would have to run in either mode - so shouldn't represent a difference, I would think?)

 

Joerg
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