Reduce size of executable produced by GHC

Question

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?

Answer 1

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.

Answer 2

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.