Reduce size of executable produced by GHC

2018-06-11 14:58:27

Using GHC version 7.4.2 with flags like -O3, I still get huge executable produced. I understand that GHC does static linking, and dependencies of the binary looks like:

    linux-vdso.so.1 (0x00007fff49bff000)
    libpcre.so.1 => /usr/lib/libpcre.so.1 (0x00007fe658d6c000)
    librt.so.1 => /usr/lib/librt.so.1 (0x00007fe658b64000)
    libutil.so.1 => /usr/lib/libutil.so.1 (0x00007fe658961000)
    libdl.so.2 => /usr/lib/libdl.so.2 (0x00007fe65875d000)
    libpthread.so.0 => /usr/lib/libpthread.so.0 (0x00007fe658541000)
    libcurl.so.4 => /usr/lib/libcurl.so.4 (0x00007fe6582e3000)
    libgmp.so.10 => /usr/lib/libgmp.so.10 (0x00007fe658074000)
    libm.so.6 => /usr/lib/libm.so.6 (0x00007fe657d7a000)
    libgcc_s.so.1 => /usr/lib/libgcc_s.so.1 (0x00007fe657b65000)
    libc.so.6 => /usr/lib/libc.so.6 (0x00007fe6577be000)
    /lib/ld-linux-x86-64.so.2 (0x00007fe658fca000)
    libssh2.so.1 => /usr/lib/libssh2.so.1 (0x00007fe657595000)
    libssl.so.1.0.0 => /usr/lib/libssl.so.1.0.0 (0x00007fe65732b000)
    libcrypto.so.1.0.0 => /usr/lib/libcrypto.so.1.0.0 (0x00007fe656f22000)
    libz.so.1 => /usr/lib/libz.so.1 (0x00007fe656d0c000

so far it looks quite good, however inside the binary I can see the lines:

GHCi runtime linker: fatal error: I found a duplicate definition for symbol
* Specifying the same object file twice on the GHCi command line 

  ....BlockedIndefinitelyOnMVar.......BlockedIndefinitelyOnSTM........AsyncException..base....GHC.IO.FD.......FD......GHC.IO.FD.setSize.

and actually a lot of text lines, including names of my functions, functions defined in other modules and so on. The question is - is it possible to remove those texts, and can GHC eliminate unused code from external libraries?

LLVM can do more optimization at link time than most other compilers. Maybe GHC has an LLVM backend and you can recompile and link some/all of your dependencies with -O4.

If you use the gcc backend, you can pass the -optc-Os flag to ghc to optimize the output for size. Perhaps you can reduce your binary by some bytes. But I would also suggest using dynamic linking as suggested before, with all it's pros and cons.

UPDATE:

Compress your executable with UPX http://en.wikipedia.org/wiki/UPX or gzexe to reduce the size of the executable.

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