gcc-4.9未定义的行为清洁剂 [英] gcc-4.9 Undefined Behavior Sanitizer

问题描述

在 gcc-4.9更改中，它说：

UndefinedBehaviorSanitizer（ubsan），一个快速未定义的行为
检测器，已被添加，并且可以通过-fsanitize = undefined启用。
各种计算将在运行时检测未定义的行为
。 UndefinedBehaviorSanitizer目前可用于
C和C ++语言。

UndefinedBehaviorSanitizer (ubsan), a fast undefined behavior detector, has been added and can be enabled via -fsanitize=undefined. Various computations will be instrumented to detect undefined behavior at runtime. UndefinedBehaviorSanitizer is currently available for the C and C++ languages.

我看了这个问题（一个C ++实现，检测未定义的行为？），但似乎已经过时了。

I looked at this question (A C++ implementation that detects undefined behavior?) but it seems fairly outdated.

此链接（ http：// gcc .gnu.org / ml / gcc-patches / 2013-06 / msg00264.html ）有一些信息，但它有几个月了。

This link (http://gcc.gnu.org/ml/gcc-patches/2013-06/msg00264.html) has some information on it, but it's several months old.

这是一个尝试添加未定义的行为清洁剂到GCC。
注意它是非常alpha版本;到目前为止，它不这么做，在
的时刻，它应该处理零个案，INT_MIN / -1和
各种移位案例（移位一个负值，移动当
第二个操作数> =比TYPE_PRECISION（first_operand）等类似。
（在整数类型上，到目前为止）

This is an attempt to add the Undefined Behavior Sanitizer to GCC. Note that it's very alpha version; so far it doesn't do that much, at the moment it should handle division by zero cases, INT_MIN / -1, and various shift cases (shifting by a negative value, shifting when second operand is >= than TYPE_PRECISION (first_operand) and suchlike. (On integer types, so far.)

从我看过的，它被移植到 gcc 从 LLVM 。

From what I've read it's being ported to gcc from LLVM.

我试过（5/0），唯一的区别似乎是这个输出：

I've tried it with (5 / 0) and the only difference seems to be this output:

main.cpp:5:19: runtime error: division by zero

b $ b

有没有人有更多的信息或它有什么特点？

Does anyone have any more information on it or what features it has?

推荐答案

添加此类检查比尝试检测所有形式的未定义行为（这在停止问题意义上几乎肯定是不可能的）。

This is more a framework for adding such checks than an attempt to detect all forms of undefined behavior (which is almost certainly impossible in the "halting problem" sense).

GCC文档将这些列为当前支持的检查：

The GCC documentation lists these as the currently supported checks:

-fsanitize = undefined
启用UndefinedBehaviorSanitizer，一个快速未定义的行为检测器。各种计算将被仪表化
以检测运行时的未定义行为。当前子选项是：

-fsanitize=undefined Enable UndefinedBehaviorSanitizer, a fast undefined behavior detector. Various computations will be instrumented to detect undefined behavior at runtime. Current suboptions are:

-fsanitize = shift 此选项启用检查移位操作的结果是否未定义。请注意，完全被认为是
未定义在C和C ++之间以及ISO
C90和C99等之间略有不同。

-fsanitize=shift This option enables checking that the result of a shift operation is not undefined. Note that what exactly is considered undefined differs slightly between C and C++, as well as between ISO C90 and C99, etc.

-fsanitize = integer-divide-by-zero 检测整数除以零以及INT_MIN / -1除法。

-fsanitize=integer-divide-by-zero Detect integer division by zero as well as INT_MIN / -1 division.

-fsanitize = unreachable 使用此选项，编译器会将__builtin_unreachable调用转为诊断消息调用。当到达__builtin_unreachable调用时，行为是
未定义。

-fsanitize=unreachable With this option, the compiler will turn the __builtin_unreachable call into a diagnostics message call instead. When reaching the __builtin_unreachable call, the behavior is undefined.

-fsanitize = vla-bound 选项指示编译器检查可变长度数组的大小是否为正。此选项不会在-std = c ++ 1y模式中产生任何影响，因为标准需要抛出
异常。

-fsanitize=vla-bound This option instructs the compiler to check that the size of a variable length array is positive. This option does not have any effect in -std=c++1y mode, as the standard requires the exception be thrown instead.

-fsanitize = null 此选项启用指针检查。特别是，当这个选项打开的应用程序尝试取消引用NULL指针时，或者如果引用
（可能是一个右值引用）被绑定到一个NULL指针，将发出一个错误
消息。

-fsanitize=null This option enables pointer checking. Particularly, the application built with this option turned on will issue an error message when it tries to dereference a NULL pointer, or if a reference (possibly an rvalue reference) is bound to a NULL pointer.

-fsanitize = return 此选项启用return语句检查。使用此选项打开的程序将在达到非空函数的结尾时发出错误消息
，而实际上不会返回值
。此选项仅在C ++中有效。

-fsanitize=return This option enables return statement checking. Programs built with this option turned on will issue an error message when the end of a non-void function is reached without actually returning a value. This option works in C++ only.

-fsanitize = signed-integer-overflow 此选项启用带符号整数溢出检查。我们检查+，*和一元
和二进制的结果不会在签名算术中溢出。注意，必须考虑
整数提升规则。也就是说，以下的
不是溢出：

-fsanitize=signed-integer-overflow This option enables signed integer overflow checking. We check that the result of +, *, and both unary and binary - does not overflow in the signed arithmetics. Note, integer promotion rules must be taken into account. That is, the following is not an overflow:

           signed char a = SCHAR_MAX;
           a++;

而 -ftrapv 导致发出带符号溢出的陷阱， -fsanitize = undefined 给出诊断消息。此
目前仅适用于C系列语言。

While -ftrapv causes traps for signed overflows to be emitted, -fsanitize=undefined gives a diagnostic message. This currently works only for the C family of languages.

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