r176333 - Add one more sanity check in SourceManager::getFileIDLoaded().

[Argyrios Kyrtzidis]

On Mar 1, 2013, at 10:03 AM, David Blaikie <dblaikie at gmail.com> wrote:

> On Fri, Mar 1, 2013 at 9:10 AM, Jordan Rose <jordan_rose at apple.com> wrote:
>> 
>> On Feb 28, 2013, at 19:43 , Argyrios Kyrtzidis <akyrtzi at gmail.com> wrote:
>> 
>>> Author: akirtzidis
>>> Date: Thu Feb 28 21:43:33 2013
>>> New Revision: 176333
>>> 
>>> URL: http://llvm.org/viewvc/llvm-project?rev=176333&view=rev
>>> Log:
>>> Add one more sanity check in SourceManager::getFileIDLoaded().
>>> 
>>> Modified:
>>>   cfe/trunk/lib/Basic/SourceManager.cpp
>>> 
>>> Modified: cfe/trunk/lib/Basic/SourceManager.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Basic/SourceManager.cpp?rev=176333&r1=176332&r2=176333&view=diff
>>> ==============================================================================
>>> --- cfe/trunk/lib/Basic/SourceManager.cpp (original)
>>> +++ cfe/trunk/lib/Basic/SourceManager.cpp Thu Feb 28 21:43:33 2013
>>> @@ -863,6 +863,11 @@ FileID SourceManager::getFileIDLoaded(un
>>>      return Res;
>>>    }
>>> 
>>> +    // Sanity checking, otherwise a bug may lead to hanging in release build.
>>> +    if (LessIndex == MiddleIndex) {
>>> +      assert(0 && "binary search missed the entry");
>> 
>> llvm_unreachable?
> 
> Or actually just remove the if/return/etc:
> 
> assert(LessIndex == MiddleIndex)
> 
> We really don't make a habit of writing asserts with fallbacks "just in case".

...except when seeing actual infinite loops occurring, in which case you defend against it; particularly when the infinite loops occur in a process using libclang.

> 
> (unreachable inside the 'if' would have the same 'problem' as removing
> the if/adding the obvious assert - in release builds we'd still
> optimize away the whole block & "a bug may lead to hanging in release
> build")
> 
>>> +      return FileID();
>>> +    }
>>>    LessIndex = MiddleIndex;
>>>  }
>>> }
>>> 
>>> 
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>> 
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