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GCC减少二进制膨胀-奇怪的副作用

toolchain compilation gcc c++

Hassan Syed · 技术社区 · 14 年前

怪诞

我编译Google协议缓冲区时没有使用额外的参数进行“膨胀”编译,并使用以下命令进行编译 ./configure CXXFLAGS="-ffunction-sections -fdata-sections" . du-h显示:

120K ./bloat/bin
124K ./bloat/include/google/protobuf/io
8.0K ./bloat/include/google/protobuf/compiler/java
12K ./bloat/include/google/protobuf/compiler/python
8.0K ./bloat/include/google/protobuf/compiler/cpp
128K ./bloat/include/google/protobuf/compiler
52K ./bloat/include/google/protobuf/stubs
848K ./bloat/include/google/protobuf
852K ./bloat/include/google
856K ./bloat/include
12K ./bloat/lib/pkgconfig
37M ./bloat/lib
38M ./bloat
20K ./unbloat/bin
124K ./unbloat/include/google/protobuf/io
8.0K ./unbloat/include/google/protobuf/compiler/java
12K ./unbloat/include/google/protobuf/compiler/python
8.0K ./unbloat/include/google/protobuf/compiler/cpp
128K ./unbloat/include/google/protobuf/compiler
52K ./unbloat/include/google/protobuf/stubs
848K ./unbloat/include/google/protobuf
852K ./unbloat/include/google
856K ./unbloat/include
12K ./unbloat/lib/pkgconfig
15M ./unbloat/lib
16M ./unbloat
53M .

 ls -gGh bloat/lib/
    total 37M
    -rw-r--r-- 1  13M 2010-09-07 13:57 libprotobuf.a
    -rwxr-xr-x 1  986 2010-09-07 13:57 libprotobuf.la
    -rw-r--r-- 1 1.6M 2010-09-07 13:57 libprotobuf-lite.a
    -rwxr-xr-x 1 1021 2010-09-07 13:57 libprotobuf-lite.la
    lrwxrwxrwx 1   25 2010-09-07 13:57 libprotobuf-lite.so -> libprotobuf-lite.so.6.0.0
    lrwxrwxrwx 1   25 2010-09-07 13:57 libprotobuf-lite.so.6 -> libprotobuf-lite.so.6.0.0
    -rwxr-xr-x 1 771K 2010-09-07 13:57 libprotobuf-lite.so.6.0.0
    lrwxrwxrwx 1   20 2010-09-07 13:57 libprotobuf.so -> libprotobuf.so.6.0.0
    lrwxrwxrwx 1   20 2010-09-07 13:57 libprotobuf.so.6 -> libprotobuf.so.6.0.0
    -rwxr-xr-x 1 5.5M 2010-09-07 13:57 libprotobuf.so.6.0.0
    -rw-r--r-- 1  12M 2010-09-07 13:57 libprotoc.a
    -rwxr-xr-x 1 1.1K 2010-09-07 13:57 libprotoc.la
    lrwxrwxrwx 1   18 2010-09-07 13:57 libprotoc.so -> libprotoc.so.6.0.0
    lrwxrwxrwx 1   18 2010-09-07 13:57 libprotoc.so.6 -> libprotoc.so.6.0.0
    -rwxr-xr-x 1 4.6M 2010-09-07 13:57 libprotoc.so.6.0.0
    drwxr-xr-x 2 4.0K 2010-09-07 13:57 pkgconfig
    ls -gGh unbloat/lib/
    total 15M
    -rw-r--r-- 1 5.8M 2010-09-07 14:03 libprotobuf.a
    -rwxr-xr-x 1  988 2010-09-07 14:03 libprotobuf.la
    -rw-r--r-- 1 764K 2010-09-07 14:03 libprotobuf-lite.a
    -rwxr-xr-x 1 1023 2010-09-07 14:03 libprotobuf-lite.la
    lrwxrwxrwx 1   25 2010-09-07 14:03 libprotobuf-lite.so -> libprotobuf-lite.so.6.0.0
    lrwxrwxrwx 1   25 2010-09-07 14:03 libprotobuf-lite.so.6 -> libprotobuf-lite.so.6.0.0
    -rwxr-xr-x 1 393K 2010-09-07 14:03 libprotobuf-lite.so.6.0.0
    lrwxrwxrwx 1   20 2010-09-07 14:03 libprotobuf.so -> libprotobuf.so.6.0.0
    lrwxrwxrwx 1   20 2010-09-07 14:03 libprotobuf.so.6 -> libprotobuf.so.6.0.0
    -rwxr-xr-x 1 2.7M 2010-09-07 14:03 libprotobuf.so.6.0.0
    -rw-r--r-- 1 3.7M 2010-09-07 14:04 libprotoc.a
    -rwxr-xr-x 1 1.1K 2010-09-07 14:04 libprotoc.la
    lrwxrwxrwx 1   18 2010-09-07 14:04 libprotoc.so -> libprotoc.so.6.0.0
    lrwxrwxrwx 1   18 2010-09-07 14:04 libprotoc.so.6 -> libprotoc.so.6.0.0
    -rwxr-xr-x 1 1.3M 2010-09-07 14:04 libprotoc.so.6.0.0
    drwxr-xr-x 2 4.0K 2010-09-07 14:03 pkgconfig

问题

--gc-sections “在连接过程中,如果不是更大的话,不允许的构建是相同的吗?是什么导致了尺寸的缩小?

背景

相关问题

我的 next question

2 回复 | 直到 7 年前

Samuel Tardieu 14 年前

-ffunction-sections -fdata-sections :当您指定 CXXFLAGS="-ffunction-sections -fdata-sections" -O2 -g -DNDEBUG . 因此,您的代码在编译时没有进行任何优化。

你应该重做你的测试 CXXFLAGS="-ffunction-sections -fdata-sections -O2 -g -DNDEBUG" 您将得到预期的(即相同的)结果。

Employed Russian 14 年前

编译 -ffunction-sections .text .text.foo , .text.bar 等)。同样适用于 -fdata-sections

但你呢关心你的建筑面积有多大。你说什么关心的是最终可执行文件(或共享库)有多大。

-Wl,--gc-sections