汇编器.weak指令仅适用于Cross Compile GCC [英] Assembler .weak directive does only work with Cross Compile GCC

问题描述

我有一个程序，可以使用2种不同的编译器进行编译:

I have a program which I compile with 2 different compilers:

用于PowerPC的GCC 3.4.4交叉编译器

GCC 4.8.1 MinGW编译器

在程序中，我使用的是汇编程序指令.weak.该文档说:

In the program I am using the assembler directive .weak . The documentation says:

Makes a symbol with weak binding globally visible to the linker.

所以我要这样:

__asm__(".weak " "foo" "\n.set " "foo" "," "dummy_foo" "\n");

清除foo弱点并将其赋予dummy_foo别名.

To cleare foo weak and give it an alias to dummy_foo.

当我交叉编译PowerPC时，此代码在GCC 3.4.4下工作正常，但在为x86目标进行编译时，它在GCC 4.8.1下不起作用. -代码已编译，但未将foo声明为weak，并且我的链接器为我提供了未定义的引用.这是什么问题?

This code works fine under GCC 3.4.4 when I cross compile für PowerPC but it doesn't work with GCC 4.8.1 when I compile for x86 target. - The Code compiles, but foo is not declared weak and my linker gives me an undefined reference. What is the problem here?

//

如BSH所建议，它必须是:

As BSH suggested, it has to be:

__asm__(".weak " "_foo" "\n.set " "_foo" "," "_dummy_foo" "\n");

如果我将此行放入与foo()声明相同的C文件中，则可以正常工作.当我将其放在单独的C文件中时，问题仍然存在(然后适用于GCC 3.4.4交叉编译器，但不适用于GCC 4.8.1)

If I put this line into the same C-File as my declaration of foo() it works fine. The problem still persists when I put it in a seperate C-File (then it works for the GCC 3.4.4 Cross Compiler, but not for the GCC 4.8.1 )

推荐答案

在MinGW中，符号前面带有下划线_foo，您需要将其更改为:

In MinGW, symbols are prefixed with an underscore, _foo, you need to change it to:

__asm__(".weak " "_foo" "\n.set " "_foo" "," "_dummy_foo" "\n");

或考虑将属性 __attribute__((weak, alias("dummy_foo")))与foo一起使用代替.

or consider using the attribute __attribute__((weak, alias("dummy_foo"))) with foo instead.

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