通过makefile传递一个gcc标志 [英] Passing a gcc flag through makefile

问题描述

我正在尝试使用 llvm 构建通行证，并且已完成构建llvm及其关联组件。但是，当我按照所有步骤构建通行证（包括 makefile ）后运行make时，我得到以下的内容：

I am trying to build a pass using llvm and I have finished building llvm and its associated components. However, when I run make after following all the steps to build a pass including the makefile, I get the following

重新定位R_X86_64_32对于`本地符号'不能用于制作共享对象;使用-fPIC重新编译

relocation R_X86_64_32 against `a local symbol' can not be used when making a shared object; recompile with -fPIC

在通过搜索错误消息找到修复程序后，我开始知道这不是特定于llvm 。一些解决方案建议我在运行configure时使用--enable-shared，但这对我的情况没有帮助。现在我想用 fPIC 重新构建llvm，如错误所述。但是，如何使用makefile执行此操作？

After tyring to find a fix by googling the error message, I came to know that this is not specific to llvm. A few solutions suggested that I should use "--enable-shared" while running configure but that didn't help my case. Now I want to re-build llvm using fPIC, as the error says. But how do I do this using the makefile?

推荐答案

看起来您可以添加-fPIC（对于位置无关的代码，您可以通过设置shell变量来设置共享库的一些内容：

Looks like you could add the -fPIC (for position-independent code, something you want for a shared library that could be loaded at any address) by setting shell variables:

export CFLAGS="$CFLAGS -fPIC"
export CXXFLAGS="$CXXFLAGS -fPIC"

查看 Makefile.rules ，这些将被拿起并使用。似乎很奇怪，它并不在那里开始。

Looking at Makefile.rules, these will be picked up and used. Seems strange that it wasn't there to begin with.

编辑：

其实，阅读更多makefiles，我发现这个链接到 LLVM Makefile Guide 。从Makefile.rules中，在Makefile中设置SHARED_LIBRARY = 1或LOADABLE_MODULE = 1（这意味着SHARED_LIBRARY）会将-fPIC放入编译器标志中。

Actually, reading more in the makefiles, I found this link to the LLVM Makefile Guide. From Makefile.rules, setting either SHARED_LIBRARY=1 or LOADABLE_MODULE=1 (which implies SHARED_LIBRARY) in Makefile will put -fPIC in the compiler flags.

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