| 1 |
On 09/28/2014 01:44 AM, Jorge Almeida wrote: |
| 2 |
> I'm having a somewhat disgusting issue on my Gentoo: binaries are |
| 3 |
> unaccountably large. |
| 4 |
> |
| 5 |
> I'm talking about C programs of my own, so no version related issues |
| 6 |
> whatsoever. The computer is a core i3 with a 32 bit system. |
| 7 |
> |
| 8 |
> Example, for the same program: |
| 9 |
> |
| 10 |
> 10275 B on an atom running Slackware 14.1 (gcc 4.8.2) |
| 11 |
> 5896 B (same, stripped with strip --strip-unneeded) |
| 12 |
> |
| 13 |
> 11675 B on i3, Gentoo, gcc 4.8.3 (with default gcc it was worse) |
| 14 |
> 9704 B stripped |
| 15 |
> |
| 16 |
> 8207 B on *the same i3 box* running LFS (gcc 4.9.1) |
| 17 |
> 5768 B stripped |
| 18 |
> |
| 19 |
> When compiling against dietlibc, the difference is even more shocking |
| 20 |
> (almost double size in Gentoo after stripping). |
| 21 |
> |
| 22 |
> Compiled with: |
| 23 |
> gcc -Os -march=i686 -fomit-frame-pointer -pipe -Wall -pedantic |
| 24 |
> -fdata-sections -ffunction-sections -Wl,--gc-sections |
| 25 |
> -fno-asynchronous-unwind-tables -std=c99 |
| 26 |
> |
| 27 |
> Gentoo: |
| 28 |
> $ gcc -v |
| 29 |
> Using built-in specs. |
| 30 |
> COLLECT_GCC=/usr/i686-pc-linux-gnu/gcc-bin/4.8.3/gcc |
| 31 |
> COLLECT_LTO_WRAPPER=/usr/libexec/gcc/i686-pc-linux-gnu/4.8.3/lto-wrapper |
| 32 |
> Target: i686-pc-linux-gnu |
| 33 |
> Configured with: |
| 34 |
> /var/tmp/portage/sys-devel/gcc-4.8.3/work/gcc-4.8.3/configure |
| 35 |
> --host=i686-pc-linux-gnu --build=i686-pc-linux-gnu --prefix=/usr |
| 36 |
> --bindir=/usr/i686-pc-linux-gnu/gcc-bin/4.8.3 |
| 37 |
> --includedir=/usr/lib/gcc/i686-pc-linux-gnu/4.8.3/include |
| 38 |
> --datadir=/usr/share/gcc-data/i686-pc-linux-gnu/4.8.3 |
| 39 |
> --mandir=/usr/share/gcc-data/i686-pc-linux-gnu/4.8.3/man |
| 40 |
> --infodir=/usr/share/gcc-data/i686-pc-linux-gnu/4.8.3/info |
| 41 |
> --with-gxx-include-dir=/usr/lib/gcc/i686-pc-linux-gnu/4.8.3/include/g++-v4 |
| 42 |
> --with-python-dir=/share/gcc-data/i686-pc-linux-gnu/4.8.3/python |
| 43 |
> --enable-languages=c,c++,fortran --enable-obsolete --enable-secureplt |
| 44 |
> --disable-werror --with-system-zlib --disable-nls |
| 45 |
> --enable-checking=release --with-bugurl=https://bugs.gentoo.org/ |
| 46 |
> --with-pkgversion='Gentoo 4.8.3' --enable-libstdcxx-time |
| 47 |
> --enable-shared --enable-threads=posix --enable-__cxa_atexit |
| 48 |
> --enable-clocale=gnu --disable-multilib --disable-altivec |
| 49 |
> --disable-fixed-point --with-arch=i686 --enable-targets=all |
| 50 |
> --disable-libgcj --enable-libgomp --disable-libmudflap |
| 51 |
> --disable-libssp --enable-lto --without-cloog |
| 52 |
> Thread model: posix |
| 53 |
> gcc version 4.8.3 (Gentoo 4.8.3) |
| 54 |
> |
| 55 |
> LFS: |
| 56 |
> ## gcc -v |
| 57 |
> Using built-in specs. |
| 58 |
> COLLECT_GCC=gcc |
| 59 |
> COLLECT_LTO_WRAPPER=/usr/libexec/gcc/i686-pc-linux-gnu/4.9.1/lto-wrapper |
| 60 |
> Target: i686-pc-linux-gnu |
| 61 |
> Configured with: ../gcc-4.9.1/configure --prefix=/usr |
| 62 |
> --enable-languages=c,c++ --disable-multilib --disable-bootstrap |
| 63 |
> --with-system-zlib |
| 64 |
> Thread model: posix |
| 65 |
> gcc version 4.9.1 (GCC) |
| 66 |
> |
| 67 |
> Slackware: |
| 68 |
> Reading specs from /slash/usr/bin/../lib/gcc/i486-slackware-linux/4.8.2/specs |
| 69 |
> COLLECT_GCC=gcc |
| 70 |
> COLLECT_LTO_WRAPPER=/slash/usr/bin/../libexec/gcc/i486-slackware-linux/4.8.2/lto-wrapper |
| 71 |
> Target: i486-slackware-linux |
| 72 |
> Configured with: ../gcc-4.8.2/configure --prefix=/usr |
| 73 |
> --libdir=/usr/lib --mandir=/usr/man --infodir=/usr/info |
| 74 |
> --enable-shared --enable-bootstrap |
| 75 |
> --enable-languages=ada,c,c++,fortran,go,java,lto,objc |
| 76 |
> --enable-threads=p osix --enable-checking=release --enable-objc-gc |
| 77 |
> --with-system-zlib --with-python-dir=/lib/python2.7/site-packages |
| 78 |
> --disable-libunwind-exceptions --enable-__cxa_atexit --enable-libssp |
| 79 |
> --enable-lto --with-gnu-ld --verbose --enable-java-home |
| 80 |
> --with-java-home=/usr/lib/jvm/jre --with-jvm-root-dir=/usr/lib/jvm |
| 81 |
> --with-jvm-jar-dir=/usr/lib/jvm/jvm-exports --with-arch-directory=i386 |
| 82 |
> --with-antlr-jar=/root/slackware-current/source/d/gcc/antlr-runtime-3.4.jar |
| 83 |
> --enable-java-awt=gtk --disable-gtktest --with-arch=i486 |
| 84 |
> --target=i486-slackware-linux --build=i486-slackware-linux |
| 85 |
> --host=i486-slackware-linux |
| 86 |
> Thread model: posix |
| 87 |
> gcc version 4.8.2 (GCC) |
| 88 |
> |
| 89 |
> I'm not elfwise, but I could post something to google drive if needed. |
| 90 |
|
| 91 |
Are you cross-compiling for different hardware? I'm just curious what results |
| 92 |
you get with --march=native. |
| 93 |
|
| 94 |
Also, I looked up data-sections and function-sections (which I'd never heard |
| 95 |
of before today :) The gcc man page says the resulting executable will be |
| 96 |
larger and slower, and not to use them "unless there are significant benefits" |
| 97 |
but then doesn't say what those benefits might be. Hm, cryptic. |
Archives