GCC的预编译头不起作用 #5858
Comments
Title: GCC’s precompiled header does not work Xmake versionv2.9.6+20241030 Operating system version and architectureLinux 6.11.5-arch1-1 Describe the problemRecurrence: Expected resultsCompile using precompiled headers Project configurationAdditional information and error logsrepair:
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看不懂你要搞啥，
你改了预编译头加了 error ，不是当然会编译不过么，这不是正常现象么。。
为什么一定要参考 cmake 去生成？只要能实现预编译的目的不就行了，这又不是标准，目前仅仅 msvc 下，才会生成 gcc/clang 下不需要。
不考虑，这会污染源码目录，最不推荐的方式。所以的中间文件都应该隔离到 build 目录下。 |
I don't understand what you are trying to do.
If you changed the precompiled header and added error , of course it won't compile. Isn't this a normal phenomenon? .
Why must we refer to cmake to generate? As long as the purpose of precompilation can be achieved, it will be fine. This is not a standard. Currently, it is only generated under msvc. Not required under gcc/clang.
Regardless, this will pollute the source code directory, which is the least recommended way. Therefore, all intermediate files should be isolated to the build directory. |
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[pch]$ xmake -v && cmake -G Ninja && ninja -v CMake Warning (dev) in CMakeLists.txt: near the top of the file, but after cmake_minimum_required(). CMake is pretending there is a "project(Project)" command on the first CMake Warning (dev) in CMakeLists.txt: -- The C compiler identification is GNU 14.2.1 should be added at the top of the file. The version specified may be lower -- Configuring done (0.4s) |
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https://gcc.gnu.org/onlinedocs/libstdc++/manual/using_headers.html |
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另外请考虑使用common/stdafx.h和stdafx.h这样的情况 |
Also consider using common/stdafx.h and stdafx.h like this |
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还是不懂你在说啥，遇到的是什么问题 |
I still don’t understand what you are talking about and what problem you are encountering. |
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首先GCC对于使用预编译头和强制包含头文件是一样的语法 大部分情况就算预编译头不生效也时能编译通过的 因此需要有个方法来确定预编译头是否生效 1.可以添加-H来检测预编译头是否被使用 https://gcc.gnu.org/onlinedocs/gcc/Preprocessor-Options.html 1.1xmake的命令行 输出无gch文件 1.2将gch所在目录提到最前 输出里包含gch但是编译错误（原因不明 gcc 14.2.1 20240910） 1.3一个正常的命令行(尽管没有build/.objs/pch/linux/x86_64/release/PCH/cxx/pch.h也能识别到gch) 2.在不被当成预编译头后 命令行实际意义为强制包含文件 -include包含的是文件名而不是完整路径 存在被搜索路径干扰的问题 3.gch不生效后内存占用增多 内存不足触发swap 大多数gcc进程卡在d状态 cpu跑不满 最小可复现工程 cat main.cpp int main() { return 0; } cat xmake.lua cat PCH/pch.h |
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你这表述的也太琐碎了，抓不到重点，看了半天才看明白咋回事。。。还不如直接说 pch 没生效，然后给个完整复现 demo 不就完事了么。。 这里主要有几个问题导致：
这两处理了，pch 就可以生效了。 至于你说的
至于 ccache 那个问题
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Your expression is too trivial and misses the point. It took me a long time to understand what was going on. . . It would be better to just say that pch does not take effect, and then give a complete reproduction demo and be done with it. . There are several main problems here:
After these two steps are taken care of, pch can take effect. As for what you said
As for the ccache issue
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#5896会导致编译错误 调用的命令行和我第二次补充的1.2相同 把gch换个名字能解决 |
#5896 will cause compilation errors. The command line called is the same as the 1.2 I added the second time. Changing the name of gch can solve the problem |
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我这里可以，没啥问题 ruki@f276d0cf2cba:/tmp/test$ tree .
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|-- PCH
| `-- pch.h
|-- main.cpp
`-- xmake.lua
1 directory, 3 files
ruki@f276d0cf2cba:/tmp/test$ xmake f -c --ccache=n
checking for platform ... linux
checking for architecture ... x86_64
ruki@f276d0cf2cba:/tmp/test$ xmake -rv
checking for gcc ... /usr/bin/gcc
checking for the c++ compiler (cxx) ... gcc
checking for /usr/bin/gcc ... ok
checking for flags (-fPIC) ... ok
checking for flags (-fvisibility-inlines-hidden) ... ok
checking for flags (-O3) ... ok
checking for flags (-Winvalid-pch) ... ok
checking for flags (-H) ... ok
checking for flags (-DNDEBUG) ... ok
[ 25%]: compiling.release PCH/pch.h
/usr/bin/gcc -c -m64 -fvisibility=hidden -fvisibility-inlines-hidden -O3 -I build/.objs/pch/linux/x86_64/release/PCH/cxx -IPCH -Winvalid-pch -H -DNDEBUG -x c++-header -o build/.objs/pch/linux/x86_64/release/PCH/cxx/pch.h.gch PCH/pch.h
checking for flags (-MMD -MF) ... ok
checking for flags (-fdiagnostics-color=always) ... ok
PCH/pch.h:2:9: warning: #pragma once in main file
2 | #pragma once
| ^~~~
[ 50%]: compiling.release main.cpp
/usr/bin/gcc -c -m64 -fvisibility=hidden -fvisibility-inlines-hidden -O3 -I build/.objs/pch/linux/x86_64/release/PCH/cxx -include pch.h -IPCH -Winvalid-pch -H -DNDEBUG -o build/.objs/pch/linux/x86_64/release/main.cpp.o main.cpp
! build/.objs/pch/linux/x86_64/release/PCH/cxx/pch.h.gch. <--------
checking for g++ ... /usr/bin/g++
checking for the linker (ld) ... g++
checking for /usr/bin/g++ ... ok
checking for flags (-fPIC) ... ok
[ 75%]: linking.release pch
/usr/bin/g++ -o build/linux/x86_64/release/pch build/.objs/pch/linux/x86_64/release/main.cpp.o -m64 -s
[100%]: build ok, spent 0.74s
ruki@f276d0cf2cba:/tmp/test$ cat ./xmake.lua
add_rules("mode.debug", "mode.release")
target("pch")
add_files("*.cpp")
add_includedirs("PCH")
set_pcxxheader("PCH/pch.h")
add_cxxflags("-Winvalid-pch")
add_cxxflags("-H")
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你的main.cpp里是不是没有#include "pch.h" |
Is there no #include "pch.h" in your main.cpp? |
之前被我改成了 |
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
ignoring duplicate directory "/usr/include/x86_64-linux-gnu/c++/11"
ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu"
ignoring nonexistent directory "/usr/lib/gcc/x86_64-linux-gnu/11/include-fixed"
ignoring nonexistent directory "/usr/lib/gcc/x86_64-linux-gnu/11/../../../../x86_64-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
build/.objs/pch/linux/x86_64/release/PCH/cxx
/usr/include/c++/11
/usr/include/x86_64-linux-gnu/c++/11
/usr/include/c++/11/backward
/usr/lib/gcc/x86_64-linux-gnu/11/include
/usr/local/include
/usr/include/x86_64-linux-gnu
/usr/include
End of search list.
GNU C++17 (Ubuntu 11.4.0-1ubuntu1~22.04) version 11.4.0 (x86_64-linux-gnu)
compiled by GNU C version 11.4.0, GMP version 6.2.1, MPFR version 4.1.0, MPC version 1.2.1, isl version isl-0.24-GMP
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: d591828bb4d392ae8b7b160e5bb0b95f
! build/.objs/pch/linux/x86_64/release/PCH/cxx/pch.h.gch
main.cpp:1:10: fatal error: build/.objs/pch/linux/x86_64/release/PCH/cxx/pch.h: No such file or directory
1 | #include "pch.h"其实 gcc 已经找到 pch.h.gch 了。。看来改了 .gch 做隔离，还是得塞个 pch.h 到 gch 对应目录下才行。。否则行为不可靠，蛋疼。还是 clang 靠谱。 |
I changed it to |
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再试下。#5902 但还是得先禁用下 ccache |
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再试下上面的 patch，gcc 下 ccache 也支持了，加了个 而 clang 下，本身就通过 -include-pch 在预处理阶段展开了，所以原本就是支持 ccache 的，但是在开启 ccache 下，每个预处理文件，都提前全部展开了，相比 no ccache + pch 反而会慢不少，这个暂时不管了，等后面有更好的方案再优化 ruki@f276d0cf2cba:/tmp/test$ rm -rf build/; xmake f -c; xmake -r
checking for platform ... linux
checking for architecture ... x86_64
[ 25%]: cache compiling.release PCH/pch.h
PCH/pch.h:2:9: warning: #pragma once in main file
2 | #pragma once
| ^~~~
[ 50%]: cache compiling.release main.cpp
! build/.objs/pch/linux/x86_64/release/PCH/cxx/pch.h.gch
. build/.objs/pch/linux/x86_64/release/PCH/cxx/pch.h
Multiple include guards may be useful for:
build/.objs/pch/linux/x86_64/release/PCH/cxx/pch.h
. /usr/include/stdc-predef.h
<command-line>
. build/.objs/pch/linux/x86_64/release/PCH/cxx/pch.h
[ 75%]: linking.release pch
[100%]: build ok, spent 0.789s |
Xmake 版本
v2.9.6+20241030
操作系统版本和架构
Linux 6.11.5-arch1-1
描述问题
复现：
1.xmake -v
2.修改预编译头 增加#error
3.使用步骤1中的GCC编译命令编译 GCC不能通过编译
期待的结果
使用预编译头编译通过
工程配置
pch.zip
附加信息和错误日志
修复：
参考CMake。
1.生成包含设置的预编译头文件的.h文件
2.在.h相同的目录生成.h.gch文件
3.只需要增加编译选项-include 生成.h文件的完整路径
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