Valgrind的在OS X上的优胜美地，给人虚假的错误？ [英] Valgrind on OS X Yosemite, giving bogus errors?
问题描述
我在学习C艰难的历程和我在练习4：介绍Valgrind的。我在Mac OS X中的优胜美地，而截至记者发稿，有没有Valgrind的为优胜美地一个稳定版本。我发现 Yosemite和Valgrind的，并使用来自顶级投回答的方向 BREW安装--HEAD的valgrind 。这种安装Valgrind的，我能够与捷思锐的运动来进行操作。然而，当我固定的应用程序，我仍然得到错误。
I'm following along in Learn C The Hard Way and I'm on Exercise 4: Introducing Valgrind. I'm on Mac OS X Yosemite, and as of this writing, there's not a stable build of Valgrind for Yosemite. I found Yosemite and Valgrind and used the directions from the top-voted answer to brew install --HEAD valgrind. This installed Valgrind and I was able to follow along with Zed's exercise. However, when I "fixed" the app, I was still getting errors.
要仔细检查，我又回到了练习3 ，该应该不会有错误，但我还是在Valgrind的得到了错误。这里的code，然后输出：
To double check, I went back to Exercise 3, which shouldn't have errors, but I still got errors in Valgrind. Here's the code and then the output:
ex3.c
#include <stdio.h>
int main()
{
int age = 10;
int height = 72;
printf("I am %d years old.\n", age);
printf("I am %d inches tall.\n", height);
return 0;
}
在的iTerm：
ransom:learn-c-the-hard-way ben$ rm -f ex3
ransom:learn-c-the-hard-way ben$ make ex3
cc -Wall -g ex3.c -o ex3
ransom:learn-c-the-hard-way ben$ valgrind ./ex3
==8795== Memcheck, a memory error detector
==8795== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
==8795== Using Valgrind-3.11.0.SVN and LibVEX; rerun with -h for copyright info
==8795== Command: ./ex3
==8795==
==8795== Conditional jump or move depends on uninitialised value(s)
==8795== at 0x1003FBC3F: _platform_memchr$VARIANT$Haswell (in /usr/lib/system/libsystem_platform.dylib)
==8795== by 0x1001EFB96: __sfvwrite (in /usr/lib/system/libsystem_c.dylib)
==8795== by 0x1001F9FE5: __vfprintf (in /usr/lib/system/libsystem_c.dylib)
==8795== by 0x10021F9AE: __v2printf (in /usr/lib/system/libsystem_c.dylib)
==8795== by 0x10021FC80: __xvprintf (in /usr/lib/system/libsystem_c.dylib)
==8795== by 0x1001F5B71: vfprintf_l (in /usr/lib/system/libsystem_c.dylib)
==8795== by 0x1001F39D7: printf (in /usr/lib/system/libsystem_c.dylib)
==8795== by 0x100000F2D: main (ex3.c:8)
==8795==
==8795== Conditional jump or move depends on uninitialised value(s)
==8795== at 0x1003FBC47: _platform_memchr$VARIANT$Haswell (in /usr/lib/system/libsystem_platform.dylib)
==8795== by 0x1001EFB96: __sfvwrite (in /usr/lib/system/libsystem_c.dylib)
==8795== by 0x1001F9FE5: __vfprintf (in /usr/lib/system/libsystem_c.dylib)
==8795== by 0x10021F9AE: __v2printf (in /usr/lib/system/libsystem_c.dylib)
==8795== by 0x10021FC80: __xvprintf (in /usr/lib/system/libsystem_c.dylib)
==8795== by 0x1001F5B71: vfprintf_l (in /usr/lib/system/libsystem_c.dylib)
==8795== by 0x1001F39D7: printf (in /usr/lib/system/libsystem_c.dylib)
==8795== by 0x100000F2D: main (ex3.c:8)
==8795==
I am 10 years old.
I am 72 inches tall.
==8795==
==8795== HEAP SUMMARY:
==8795== in use at exit: 38,888 bytes in 426 blocks
==8795== total heap usage: 506 allocs, 80 frees, 45,016 bytes allocated
==8795==
==8795== LEAK SUMMARY:
==8795== definitely lost: 0 bytes in 0 blocks
==8795== indirectly lost: 0 bytes in 0 blocks
==8795== possibly lost: 0 bytes in 0 blocks
==8795== still reachable: 4,096 bytes in 1 blocks
==8795== suppressed: 34,792 bytes in 425 blocks
==8795== Rerun with --leak-check=full to see details of leaked memory
==8795==
==8795== For counts of detected and suppressed errors, rerun with: -v
==8795== Use --track-origins=yes to see where uninitialised values come from
==8795== ERROR SUMMARY: 4 errors from 2 contexts (suppressed: 0 from 0)
它说，我得到条件跳转或移动依赖于未初始化值（S）在 ex3.c：8 ，而高度变量初始化第6行。
It says I'm getting Conditional jump or move depends on uninitialized value(s) on ex3.c:8, but the height variable is initialized on line 6.
我的猜的是，这是在优胜美地与Valgrind的问题，错误的是假的，但我很新的C，虽然我相当肯定的code是正确的，我也不知道是否有可能是我丢失的东西。
My guess is that this is a problem with Valgrind on Yosemite and the error is bogus, but I'm very new to C and while I'm fairly certain the code is correct, I also don't know if there might be something I'm missing.
时它Valgrind的还是我的code的一个问题？
Is it a problem with Valgrind or my code?
推荐答案
这具体报告代表Valgrind的的假阳性。 Valgrind的约塞米蒂上还没有完全覆盖所有的角落情况下，系统库和最佳化的库使用。
This specific report is a false positive on Valgrind's behalf. Valgrind on Yosemite does not yet fully cover the system libraries for all corner cases and optimisations those libraries use.
下面的提示是函数名_platform_memchr $ VARIANT $ Haswell的，即这个bug的presence将取决于你的系统硬件，在这种情况下，你是否有一个基于Haswell的英特尔CPU。
The hint here is the function name _platform_memchr$VARIANT$Haswell i.e. the presence of this bug will depend on your system hardware, in this case whether you have an Intel Haswell-based CPU.
这将是巨大的，如果你能报告每个Valgrind的的 http://valgrind.org/support/bug_reports.html以便它可以先于下一个稳定Valgrind的释放是固定的。
It would be great if you can report this bug per Valgrind's http://valgrind.org/support/bug_reports.html so that it can be fixed prior to the next stable Valgrind release.
的披露：我的Valgrind的开发者之一谁贡献补丁支持OS X 10.10 的
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