Question

我使用gcc test.c或clang test.c编译了这个C程序：

int main (void) {
    return 0;
}

valgrind ./a.out给了我这个：

==9232== Memcheck, a memory error detector
==9232== Copyright (C) 2002-2011, and GNU GPL'd, by Julian Seward et al.
==9232== Using Valgrind-3.7.0 and LibVEX; rerun with -h for copyright info
==9232== Command: ./a.out
==9232== 
==9232== Conditional jump or move depends on uninitialised value(s)
==9232==    at 0x4017876: index (in /usr/lib/ld-2.16.so)
==9232==    by 0x4007902: expand_dynamic_string_token (in /usr/lib/ld-2.16.so)
==9232==    by 0x4008204: _dl_map_object (in /usr/lib/ld-2.16.so)
==9232==    by 0x400180D: map_doit (in /usr/lib/ld-2.16.so)
==9232==    by 0x400E785: _dl_catch_error (in /usr/lib/ld-2.16.so)
==9232==    by 0x40010DB: do_preload (in /usr/lib/ld-2.16.so)
==9232==    by 0x4004546: dl_main (in /usr/lib/ld-2.16.so)
==9232==    by 0x4014B5D: _dl_sysdep_start (in /usr/lib/ld-2.16.so)
==9232==    by 0x4004DFD: _dl_start (in /usr/lib/ld-2.16.so)
==9232==    by 0x4001627: ??? (in /usr/lib/ld-2.16.so)
==9232== 
==9232== Conditional jump or move depends on uninitialised value(s)
==9232==    at 0x401787B: index (in /usr/lib/ld-2.16.so)
==9232==    by 0x4007902: expand_dynamic_string_token (in /usr/lib/ld-2.16.so)
==9232==    by 0x4008204: _dl_map_object (in /usr/lib/ld-2.16.so)
==9232==    by 0x400180D: map_doit (in /usr/lib/ld-2.16.so)
==9232==    by 0x400E785: _dl_catch_error (in /usr/lib/ld-2.16.so)
==9232==    by 0x40010DB: do_preload (in /usr/lib/ld-2.16.so)
==9232==    by 0x4004546: dl_main (in /usr/lib/ld-2.16.so)
==9232==    by 0x4014B5D: _dl_sysdep_start (in /usr/lib/ld-2.16.so)
==9232==    by 0x4004DFD: _dl_start (in /usr/lib/ld-2.16.so)
==9232==    by 0x4001627: ??? (in /usr/lib/ld-2.16.so)
==9232== 
==9232== 
==9232== HEAP SUMMARY:
==9232==     in use at exit: 0 bytes in 0 blocks
==9232==   total heap usage: 0 allocs, 0 frees, 0 bytes allocated
==9232== 
==9232== All heap blocks were freed -- no leaks are possible
==9232== 
==9232== For counts of detected and suppressed errors, rerun with: -v
==9232== Use --track-origins=yes to see where uninitialised values come from
==9232== ERROR SUMMARY: 2 errors from 2 contexts (suppressed: 0 from 0)

GCC版本4.7.1和Clang版本3.1。这怎么了？我的记忆有问题吗？自从我上次使用valgrind以来有一段时间，但我认为这不是正常行为。 Yelp的？

解决方案：从我从@Shawn学到的东西可以使用valgrind .supp文件来抑制这些链接器错误。我所做的是使用--gen-suppressions=all选项在我的程序上运行valgrind：

valgrind --gen-suppressions=all ./a.out

然后我提取括在括号中的新块并将它们直接放入文件my.supp：

{  
   <linker>
   Memcheck:Cond
   fun:index
   fun:expand_dynamic_string_token
   fun:_dl_map_object
   fun:map_doit
   fun:_dl_catch_error
   fun:do_preload
   fun:dl_main
   fun:_dl_sysdep_start
   fun:_dl_start
   obj:/usr/lib/ld-2.16.so
}

现在我可以使用--suppressions选项运行valgrind来指向我的新文件并且消息将被禁止：

valgrind --suppressions=/home/foo/my.supp ./a.out

Answer 1

这是know issue，其中valgrind通常为addressed using valgrind suppressions。假设您的发行版已报告此问题，则抑制列表应立即更新，并在下次更新时消失。

现在，忽略该消息是安全的。

如果它困扰您，您可以维护your own suppressions file并使用它，直到您的发行版更新默认文件（通常是/var/lib/valgrind/default.supp）。

Answer 2

这是动态链接器中的“问题”并且很常见。它出现在main()之前。您可以忽略该消息。

Valgrind报告空C程序的未初始化值

2 个答案: