使GCC编译而不插入调用memcpy [英] Getting GCC to compile without inserting call to memcpy

问题描述

我目前使用GCC 4.5.3，为PowerPC 440编译，并编译一些不需要libc的代码。我没有对memcpy（）的任何直接调用，但编译器似乎在构建期间插入一个。

有链接器选项，如-nostdlib，-nostartfiles ，-nodefaultlibs，但我无法使用它们，因为我不是在链接阶段。我只是编译。用这样的：

  $ powerpc-440-eabi-gcc -O2 -g -c -o output.o input。 c 
  

如果我用nm检查output.o，我看到memcpy的引用：

  $ powerpc-440-eabi-nm output.o | grep memcpy 
 U memcpy 
 $ 
  

GCC手册页删除调用memcpy和其他libc调用与链接器，但我不想让编译器插入他们在第一位，因为我使用一个完全不同的链接器（不是GNU的ld，它不知道感谢您提供任何帮助。

解决方案

>您需要使用-fno-builtin禁用该优化。我有一个问题，当试图编译memcpy的C库。它自称。糟糕！

I'm currently using GCC 4.5.3, compiled for PowerPC 440, and am compiling some code that doesn't require libc. I don't have any direct calls to memcpy(), but the compiler seems to be inserting one during the build.

There are linker options like -nostdlib, -nostartfiles, -nodefaultlibs but I'm unable to use them as I'm not doing the linking phase. I'm only compiling. With something like this:

$ powerpc-440-eabi-gcc -O2 -g -c -o output.o input.c

If I check the output.o with nm, I see a reference to memcpy:

$ powerpc-440-eabi-nm output.o | grep memcpy
     U memcpy
$ 

The GCC man page makes it clear how to remove calls to memcpy and other libc calls with the linker, but I don't want the compiler to insert them in the first place, as I'm using a completely different linker (not GNU's ld, and it doesn't know about libc).

Thanks for any help you can provide.

解决方案

You need to disable a that optimization with -fno-builtin. I had this problem once when trying to compile memcpy for a C library. It called itself. Oops!

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