Unable to use asan with XCode on Mac

[Amit Kumar]

I currently work on a product which has 200+ plugins and the code is written in C++. This application works on both Mac and Windows. I have been using Guard malloc to find memory related issues in this product. Guard malloc has been very useful and it has found several issues in the codebase, however, it also misses many issues. I have evaluated valgrind but that makes the application so slow that it is practically useless for our purpose.

I was very much interested in evaluating address sanitizer. The problem is that I am unable to use it.

Earlier versions of Xcode used to support the flag -faddress-sanitizer, however even a basic cocoa application built using this used to crash. In the newer versions of xcode, -faddress-sanitizer gives unsupported flag error. The newer way of specifying the flag -faddress=sanitize has apparently no effect.

This is very discouraging for me that I am unable to use asan even with a very simple cocoa application on mac.

Do I need to build clang myself? Is there any hope that I will be able to use asan on Mac.

I have gone through the following link:

https://code.google.com/p/address-sanitizer/wiki/AddressSanitizerForMacImplementationDetails

Thanks,

Amit

[Alexander Potapenko]

Yes, right now you have to build Clang yourself. ASan isn't officially
supported by Apple, that's why it's disabled in Xcode.
See http://code.google.com/p/address-sanitizer/wiki/HowToBuild for the
build instructions. There's also pretty much information about using
the trunk Clang with Xcode on stackoverflow.com.

[Amit Kumar]

Hi,

I am reviving this 3 years old thread. The good news is that address sanitizer is now officially supported by Apple in Xcode 7.

Thanks everyone.

Could it be a good idea to create a release build (highly optimized) in order to use with asan? I have created a debug build (all optimizations off) and it is working reasonably well with asan so I have no issues in using the debug build.

I read on the asan page: "To get a reasonable performance add -O1 or higher."

Does this imply that if performance is not an issue then disabling all optimizations (-O0) and creating a debug build may work the best?

What is the optimization level used for chrome asan builds? 

Thanks,

Amit

[Konstantin Serebryany]

On Sun, May 8, 2016 at 10:03 AM, Amit Kumar <amit...@gmail.com> wrote:

Hi,

I am reviving this 3 years old thread. The good news is that address sanitizer is now officially supported by Apple in Xcode 7.

Thanks everyone.

Could it be a good idea to create a release build (highly optimized) in order to use with asan? I have created a debug build (all optimizations off) and it is working reasonably well with asan so I have no issues in using the debug build.

If performance of a debug build is ok for you, a highly optimized build will not find anything new. 

There are of course some exceptions, e.g. we once found a bug in the optimizer itself with asan.

Or there could be bugs that depend on timing and don't trigger in debug build.

Or some other kind of undefined behavior that will trigger a bug only in optimized build and then will manifest as a memory corruption bug. 

 

I read on the asan page: "To get a reasonable performance add -O1 or higher."

Does this imply that if performance is not an issue then disabling all optimizations (-O0) and creating a debug build may work the best?

Mostly yes. Although frankly I don't have much experience with using asan+O0. 

We always use it with O1 or O2. 

 

What is the optimization level used for chrome asan builds? 

-O2. 

In a large internal project we use -O1 but considering to migrate to -O2 due to better performance. 

 

Thanks,

Amit

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[Konstantin Serebryany]

On Sun, May 8, 2016 at 10:03 AM, Amit Kumar <amit...@gmail.com> wrote:

Hi,

I am reviving this 3 years old thread. The good news is that address sanitizer is now officially supported by Apple in Xcode 7.

Thanks everyone.

Could it be a good idea to create a release build (highly optimized) in order to use with asan? I have created a debug build (all optimizations off) and it is working reasonably well with asan so I have no issues in using the debug build.

If performance of a debug build is ok for you, a highly optimized build will not find anything new. 

There are of course some exceptions, e.g. we once found a bug in the optimizer itself with asan.

Or there could be bugs that depend on timing and don't trigger in debug build.

Or some other kind of undefined behaviour that will trigger a bug only in optimized build and

 

I read on the asan page: "To get a reasonable performance add -O1 or higher."

Does this imply that if performance is not an issue then disabling all optimizations (-O0) and creating a debug build may work the best?

Mostly yes. Although frankly I don't have much experience with using asan+O0. 

We always use it with O1 or O2. 

 

What is the optimization level used for chrome asan builds? 

-O2. 

In a large internal project we use -O1 but considering to migrate to -O2 due to better performance. 

 

Thanks,

Amit

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