feat: Optimize compilation parameters #114
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| @@ -32,14 +32,16 @@ endif() | |||
| set (BUILD_DOCS ON CACHE BOOL "Generate doxygen-based documentation") | |||
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| # CXX FILAGS | |||
| if (NOT CMAKE_BUILD_TYPE) | |||
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设置默认 CMAKE_BUILD_TYPE 为 Release， 我们的 debian rules 都没有设置这个参数，反而 arch，nix 这些移植的发行版设置了
这里设置一下默认，不改 debian 也行
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我发现 debian 好像默认是用 RelWithDebInfo 发布的，等下测试一下
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应该不需要指定 cmake.org/cmake/help/latest/variable/CMAKE_BUILD_TYPE.html
The default value is often an empty string, but this is usually not desirable and one of the other standard build types is usually more appropriate.
如果编译时没有设置这个 environment variable，同时没有-D传参数设置，就会使用默认的空字符串，文档也说了这个不太好，应该用 one of the other standard build types（Debug, Release, RelWithDebInfo and MinSizeRel）
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随便说一下，debain 构建时默认会传入 None，不是 empty string，但效果和 empty string 一样，不会加任何（-O1,-O2...-g）参数，但 debain 会通过环境变量 CXXFLAG 传入 -O2 -g (效果和RelWithDebInfo一样)
| set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fPIC -Wall -Wextra") | ||
| set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -Wl,--as-needed") | ||
| if (CMAKE_BUILD_TYPE STREQUAL "Debug") | ||
| set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -O0 -g -fsanitize=address -fno-omit-frame-pointer") |
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Debug 模式肯定有 -O0 -g 啊，不用自己加的
| set(BUILD_TESTING ON) | ||
| else () | ||
| set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Ofast") |
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除了debug，还有 RelWithDebInfo 和 MinSizeRel，这里设置 -Ofast 会破坏这两个模式，比如 MinSizeRel 用 -Os 优化大小，-Ofast 会破坏这种优化
CMakeLists.txt
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| endif () | ||
| string(REPLACE "-O3" "-Ofast" CMAKE_CXX_FLAGS_RELEASE ${CMAKE_CXX_FLAGS_RELEASE}) |
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如果是 Release 模式设置 Ofast 最好这样写，另外，默认的 O3 已经是高级别优化了，有必要用 Ofast（在 O3 基础上增加破坏语言标准的优化） 吗？
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@Groveer 你看看是不是这样子的，如果是的话很多cmake都要改动呢 |
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Doc Check bot |
| set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fPIC -Wall -Wextra") | ||
| set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -Wl,--as-needed") | ||
| if (CMAKE_BUILD_TYPE STREQUAL "Debug") | ||
| set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -O0 -g -fsanitize=address -fno-omit-frame-pointer") |
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还有一个问题，msvc 用的是 / 而不是 -， 比如 /O2, /g 这些 flag 在windons 上没法用吧
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那加判断好一些 if(LINUX) if(Win32) if (MSVC)
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加了 if (NOT MSVC)， g++ 和 clang 应该都能接受
至于 MSVC 特有参数，等有人适配 windows 再加吧
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CMAKE_BUILD_TYPE |
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即使 debian rules 没有写，也会主动传 -DCMAKE_BUILD_TYPE=None 参数，同时给 CMAKE_CXX_FLAGS 传参 -g -O2 -fdebug-prefix-map=/build/dtkcore-1.0.0=. -fstack-protector-strong -Wformat -Werror=format-security -Wdate-time -D_FORTIFY_SOURCE=2 没有使用 RelWithDebInfo， debian 的 -g -O2 是构建时传的 CXXFLAGS https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=730636 这里有一些讨论 |
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Log: Optimize compilation parameters
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/merge |
Log: Optimize compilation parameters
Ref: https://deepin-community.github.io/sig-dde-porting/posts/compile_flag